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Ange Diouf, , , Miguel Chagnon, Naïm Khoury, Marc Kotowski, , David Landry, , , et al.
Radiology, Volume 286, pp 1008-1015; https://doi.org/10.1148/radiol.2017170681

Abstract:
To evaluate the diagnostic accuracy and reliability of computed tomographic (CT) angiography to distinguish true cervical internal carotid artery (ICA) occlusion from pseudo-occlusion (defined as an isolated intracranial thrombus that impedes ascending blood flow) in the context of acute stroke. This was a retrospective study of patients who underwent thrombectomy with preprocedural CT angiography that helps to demonstrate a lack of attenuation in the cervical ICA on the symptomatic side (24 men and 13 women; mean age, 63 years; age range, 30–86 years). Seven readers, including five neuroradiologists and two interventional neuroradiology fellows, independently reviewed the CT angiography images to assess whether there was true cervical ICA occlusion. Their results were compared with digital subtraction angiography (DSA) as the reference standard. Sensitivity and specificity for detecting true occlusion as well as accuracy and diagnostic odds ratio were calculated, with inter- and intraobserver κ statistics. Cervical ICA pseudo-occlusion occurred in 12 of 37 patients (32.4%) with nonattenuation of the cervical ICA on the symptomatic side. Interobserver agreement coefficients did not reach the substantial value of 0.61 for either pairs or groups of readers. The cohort’s average sensitivity and specificity was 68% (95% confidence interval [CI]: 59%, 76%) and 75% (95% CI: 71%, 80%), respectively, with a diagnostic odds ratio of 8 (95% CI: 3, 18) and only fair interobserver agreement (κ = 0.32; 95% CI: 0.16, 0.47). In the context of acute ischemic stroke with ipsilateral ICA nonattenuation at single-phase CT angiography, even specialized radiologists may not reliably distinguish true cervical occlusion from pseudo-occlusion. © RSNA, 2017 Online supplemental material is available for this article.
, Karla Kerlikowske, Iryna V. Lobach, Michael B. Hofmann, , , ,
Radiology, Volume 286, pp 822-829; https://doi.org/10.1148/radiol.2017170811

Abstract:
To evaluate the effect of background parenchymal enhancement (BPE) on breast magnetic resonance (MR) imaging interpretive performance in a large multi-institutional cohort with independent analysis of screening and diagnostic MR studies. Analysis of 3770 breast MR studies was conducted. Examinations were performed in 2958 women at six participating facilities in the San Francisco Bay Area from January 2010 to October 2012. Findings were recorded prospectively in the San Francisco Mammography Registry. Performance measures were compared between studies with low BPE (mild or minimal) and those with high BPE (moderate or marked) by using binomial tests of proportions. Of 1726 MR imaging studies in the screening group, 1301 were classified as having low BPE and 425 were classified as having high BPE (75% vs 25%, respectively; P< .001). Of 2044 MR imaging studies in the diagnostic group, 1443 were classified as having low BPE and 601 were classified as having high BPE (71% vs 29%, respectively; P< .001). For low versus high BPE groups at screening, abnormal interpretation rate was 157 of 1301 versus 111 of 424 (12% vs 26%, P< .001); biopsy recommendation rate was 85 of 1301 versus 54 of 424 (7% vs 13%, P< .001); and specificity was 89% (95% confidence interval [CI]: 87, 91) versus 75% (95% CI: 71, 80) (P = .01). For the low versus high BPE groups at diagnostic MR imaging, biopsy recommendation rate was 325 of 1443 versus 195 of 601 (23% vs 32%, P< .001); and specificity was 86% (95% CI: 84, 88) versus 75% (95% CI: 74, 82) (P< .001). There were no significant differences between studies with low versus high BPE in sensitivity for screening (76% [95% CI: 55, 91] vs 83% [95% CI: 52, 98]; P = .94) or diagnostic (93% [95% CI: 87, 97] vs 96% [95% CI: 87, 99]; P = .69) MR imaging, nor were there significant differences in cancer detection rate per 1000 patients between the low BPE versus high BPE groups for screening (15 per 1000 vs 24 per 1000, P = .30) or diagnostic (78 per 1000 vs 85 per 1000, P = .64) MR imaging. Relative to MR studies with minimal or mild BPE, those with moderate or marked BPE were associated with higher abnormal interpretation and biopsy rates and lower specificity, with no difference in cancer detection rate. © RSNA, 2017 Online supplemental material is available for this article.
Radiology, Volume 286, pp 887-896; https://doi.org/10.1148/radiol.2017170706

Abstract:
To investigate diagnostic performance by using a deep learning method with a convolutional neural network (CNN) for the differentiation of liver masses at dynamic contrast agent–enhanced computed tomography (CT). This clinical retrospective study used CT image sets of liver masses over three phases (noncontrast-agent enhanced, arterial, and delayed). Masses were diagnosed according to five categories (category A, classic hepatocellular carcinomas [HCCs]; category B, malignant liver tumors other than classic and early HCCs; category C, indeterminate masses or mass-like lesions [including early HCCs and dysplastic nodules] and rare benign liver masses other than hemangiomas and cysts; category D, hemangiomas; and category E, cysts). Supervised training was performed by using 55 536 image sets obtained in 2013 (from 460 patients, 1068 sets were obtained and they were augmented by a factor of 52 [rotated, parallel-shifted, strongly enlarged, and noise-added images were generated from the original images]). The CNN was composed of six convolutional, three maximum pooling, and three fully connected layers. The CNN was tested with 100 liver mass image sets obtained in 2016 (74 men and 26 women; mean age, 66.4 years ± 10.6 [standard deviation]; mean mass size, 26.9 mm ± 25.9; 21, nine, 35, 20, and 15 liver masses for categories A, B, C, D, and E, respectively). Training and testing were performed five times. Accuracy for categorizing liver masses with CNN model and the area under receiver operating characteristic curve for differentiating categories A–B versus categories C–E were calculated. Median accuracy of differential diagnosis of liver masses for test data were 0.84. Median area under the receiver operating characteristic curve for differentiating categories A–B from C–E was 0.92. Deep learning with CNN showed high diagnostic performance in differentiation of liver masses at dynamic CT. © RSNA, 2017 Online supplemental material is available for this article.
Kelley Salem, Manoj Kumar, Ginny L. Powers, Justin J. Jeffery, Yongjun Yan, Aparna M. Mahajan,
Radiology, Volume 286, pp 856-864; https://doi.org/10.1148/radiol.2017162956

Abstract:
Purpose To determine the binding specificity of 18F-16α-17β-fluoroestradiol (FES) in estrogen receptor (ER) α–positive breast cancer cells and tumor xenografts. Materials and Methods Protocols were approved by the office of biologic safety and institutional animal care and use committee. By using ER-negative MDA-MB-231 breast cancer cells, clonal lines were created that expressed either wild-type (WT; 231 WT ER) or G521R mutant ERα (231 G521R ER), which is defective in estradiol binding. ERα protein levels, subcellular localization, and transcriptional function were confirmed. FES binding was measured by using an in vitro cell uptake assay. In vivo FES uptake was measured in tumor xenografts by using small-animal positron emission tomographic/computed tomographic imaging of 24 mice (17 WT ER tumors, nine mutant G521R ER tumors, eight MDA-MB-231 tumors, and four MCF-7 ER-positive tumors). Statistical significance was determined by using Mann-Whitney (Wilcoxon rank sum) test. Results ERα transcriptional function was abolished in the mutated 231 G521R ER cells despite appropriate receptor protein expression and nuclear localization. In vitro FES binding in the 231 G521R ER cells was reduced to that observed in the parental cells. Similarly, there was no significant FES uptake in the 231 G521R ER xenografts (percent injected dose [ID] per gram, 0.49 ± 0.042), which was similar to the negative control MDA-MB-231 xenografts (percent ID per gram, 0.42 ± 0.051; P = .20) and nonspecific muscle uptake (percent ID per gram, 0.41 ± 0.0095; P = .06). Conclusion This study showed that FES retention in ER-positive breast cancer is strictly dependent on an intact receptor ligand-binding pocket and that FES binds to ERα with high specificity. These results support the utility of FES imaging for assessing tumor heterogeneity by localizing immunohistochemically ER-positive metastases that lack receptor-binding functionality. © RSNA, 2017 Online supplemental material is available for this article.
Matthias Rief, Marcus Y. Chen, Andrea L. Vavere, Benjamin Kendziora, Julie M. Miller, W. Patricia Bandettini, Christopher Cox, Richard T. George, João Lima, Marcelo Di Carli, et al.
Published: 1 February 2018
Radiology, Volume 286, pp 461-470; https://doi.org/10.1148/radiol.2017162447

Abstract:
To compare the diagnostic performance of stress myocardial computed tomography (CT) perfusion with that of stress myocardial magnetic resonance (MR) perfusion imaging in the detection of coronary artery disease (CAD). All patients gave written informed consent prior to inclusion in this institutional review board–approved study. This two-center substudy of the prospective Combined Noninvasive Coronary Angiography and Myocardial Perfusion Imaging Using 320-Detector Row Computed Tomography (CORE320) multicenter trial included 92 patients (mean age, 63.1 years ± 8.1 [standard deviation]; 73% male). All patients underwent perfusion CT and perfusion MR imaging with either adenosine or regadenoson stress. The predefined reference standards were combined quantitative coronary angiography (QCA) and single-photon emission CT (SPECT) or QCA alone. Results from coronary CT angiography were not included, and diagnostic performance was evaluated with the Mantel-Haenszel test stratified by disease status. The prevalence of CAD was 39% (36 of 92) according to QCA and SPECT and 64% (59 of 92) according to QCA alone. When compared with QCA and SPECT, per-patient diagnostic accuracy of perfusion CT and perfusion MR imaging was 63% (58 of 92) and 75% (69 of 92), respectively (P = .11); sensitivity was 92% (33 of 36) and 83% (30 of 36), respectively (P = .45); and specificity was 45% (25 of 56) and 70% (39 of 56), respectively (P< .01). When compared with QCA alone, diagnostic accuracy of CT perfusion and MR perfusion imaging was 82% (75 of 92) and 74% (68 of 92), respectively (P = .27); sensitivity was 90% (53 of 59) and 69% (41 of 59), respectively (P< .01); and specificity was 67% (22 of 33) and 82% (27 of 33), respectively (P = .27). This multicenter study shows that the diagnostic performance of perfusion CT is similar to that of perfusion MR imaging in the detection of CAD. © RSNA, 2017 Online supplemental material is available for this article.
Logan Hubbard, Jerry Lipinski, Benjamin Ziemer, Shant Malkasian, Bahman Sadeghi, Hanna Javan, Elliott M. Groves, Brian Dertli,
Published: 1 January 2018
Radiology, Volume 286, pp 93-102; https://doi.org/10.1148/radiol.2017162821

Abstract:
To retrospectively validate a first-pass analysis (FPA) technique that combines computed tomographic (CT) angiography and dynamic CT perfusion measurement into one low-dose examination. The study was approved by the animal care committee. The FPA technique was retrospectively validated in six swine (mean weight, 37.3 kg ± 7.5 [standard deviation]) between April 2015 and October 2016. Four to five intermediate-severity stenoses were generated in the left anterior descending artery (LAD), and 20 contrast material–enhanced volume scans were acquired per stenosis. All volume scans were used for maximum slope model (MSM) perfusion measurement, but only two volume scans were used for FPA perfusion measurement. Perfusion measurements in the LAD, left circumflex artery (LCx), right coronary artery, and all three coronary arteries combined were compared with microsphere perfusion measurements by using regression, root-mean-square error, root-mean-square deviation, Lin concordance correlation, and diagnostic outcomes analysis. The CT dose index and size-specific dose estimate per two-volume FPA perfusion measurement were also determined. FPA and MSM perfusion measurements (PFPA and PMSM) in all three coronary arteries combined were related to reference standard microsphere perfusion measurements (PMICRO), as follows: PFPA_COMBINED = 1.02 PMICRO_COMBINED + 0.11 (r = 0.96) and PMSM_COMBINED = 0.28 PMICRO_COMBINED + 0.23 (r = 0.89). The CT dose index and size-specific dose estimate per two-volume FPA perfusion measurement were 10.8 and 17.8 mGy, respectively. The FPA technique was retrospectively validated in a swine model and has the potential to be used for accurate, low-dose vessel-specific morphologic and physiologic assessment of coronary artery disease. © RSNA, 2017
, , Sonia Gaur, Marcelino Bernardo, , Francesca V. Mertan, , Vanesa Moreno, , , et al.
Published: 1 January 2018
Radiology, Volume 286, pp 186-195; https://doi.org/10.1148/radiol.2017152877

Abstract:
Purpose To characterize clinically important prostate cancers missed at multiparametric (MP) magnetic resonance (MR) imaging. Materials and Methods The local institutional review board approved this HIPAA-compliant retrospective single-center study, which included 100 consecutive patients who had undergone MP MR imaging and subsequent radical prostatectomy. A genitourinary pathologist blinded to MP MR findings outlined prostate cancers on whole-mount pathology slices. Two readers correlated mapped lesions with reports of prospectively read MP MR images. Readers were blinded to histopathology results during prospective reading. At histopathologic examination, 80 clinically unimportant lesions (<5 mm; Gleason score, 3+3) were excluded. The same two readers, who were not blinded to histopathologic findings, retrospectively reviewed cancers missed at MP MR imaging and assigned a Prostate Imaging Reporting and Data System (PI-RADS) version 2 score to better understand false-negative lesion characteristics. Descriptive statistics were used to define patient characteristics, including age, prostate-specific antigen (PSA) level, PSA density, race, digital rectal examination results, and biopsy results before MR imaging. Student t test was used to determine any demographic differences between patients with false-negative MP MR imaging findings and those with correct prospective identification of all lesions. Results Of the 162 lesions, 136 (84%) were correctly identified with MP MR imaging. Size of eight lesions was underestimated. Among the 26 (16%) lesions missed at MP MR imaging, Gleason score was 3+4 in 17 (65%), 4+3 in one (4%), 4+4 in seven (27%), and 4+5 in one (4%). Retrospective PI-RADS version 2 scores were assigned (PI-RADS 1, n = 8; PI-RADS 2, n = 7; PI-RADS 3, n = 6; and PI-RADS 4, n = 5). On a per-patient basis, MP MR imaging depicted clinically important prostate cancer in 99 of 100 patients. At least one clinically important tumor was missed in 26 (26%) patients, and lesion size was underestimated in eight (8%). Conclusion Clinically important lesions can be missed or their size can be underestimated at MP MR imaging. Of missed lesions, 58% were not seen or were characterized as benign findings at second-look analysis. Recognition of the limitations of MP MR imaging is important, and new approaches to reduce this false-negative rate are needed. © RSNA, 2017 Online supplemental material is available for this article.
, , Lynn S. Broderick, Ella A. Kazerooni, Cristopher A. Meyer
RadioGraphics, Volume 37, pp 1975-1993; https://doi.org/10.1148/rg.2017170051

Abstract:
In response to the recommendation of the U.S. Preventive Services Task Force and the coverage decision by the Centers for Medicare and Medicaid Services for lung cancer screening (LCS) computed tomography (CT), the American College of Radiology introduced the Lung CT Screening Reporting and Data System (Lung-RADS) in 2014 to standardize the reporting and management of screening-detected lung nodules. As with many first-edition guidelines, questions arise when such reporting systems are used in daily practice. In this article, a collection of 15 LCS-related scenarios are presented that address situations in which the Lung-RADS guidelines are unclear or situations that are not currently addressed in the Lung-RADS guidelines. For these 15 scenarios, the authors of this article provide the reader with recommendations that are based on their collective experiences, with the hope that future versions of Lung-RADS will provide additional guidance, particularly as more data from widespread LCS are collected and analyzed. ©RSNA, 2017
, Regina Barzilay, Adam B. Yedidia, Nicholas J. Locascio, Lili Yu,
Radiology, Volume 286, pp 810-818; https://doi.org/10.1148/radiol.2017170549

Abstract:
To develop a machine learning model that allows high-risk breast lesions (HRLs) diagnosed with image-guided needle biopsy that require surgical excision to be distinguished from HRLs that are at low risk for upgrade to cancer at surgery and thus could be surveilled. Consecutive patients with biopsy-proven HRLs who underwent surgery or at least 2 years of imaging follow-up from June 2006 to April 2015 were identified. A random forest machine learning model was developed to identify HRLs at low risk for upgrade to cancer. Traditional features such as age and HRL histologic results were used in the model, as were text features from the biopsy pathologic report. One thousand six HRLs were identified, with a cancer upgrade rate of 11.4% (115 of 1006). A machine learning random forest model was developed with 671 HRLs and tested with an independent set of 335 HRLs. Among the most important traditional features were age and HRL histologic results (eg, atypical ductal hyperplasia). An important text feature from the pathologic reports was “severely atypical.” Instead of surgical excision of all HRLs, if those categorized with the model to be at low risk for upgrade were surveilled and the remainder were excised, then 97.4% (37 of 38) of malignancies would have been diagnosed at surgery, and 30.6% (91 of 297) of surgeries of benign lesions could have been avoided. This study provides proof of concept that a machine learning model can be applied to predict the risk of upgrade of HRLs to cancer. Use of this model could decrease unnecessary surgery by nearly one-third and could help guide clinical decision making with regard to surveillance versus surgical excision of HRLs. © RSNA, 2017
, , , Cesare Hassan, Gabriella Iussich, Marco Silvani, Arrigo Arrigoni, ,
Radiology, Volume 286, pp 873-883; https://doi.org/10.1148/radiol.2017170228

Abstract:
Purpose To compare the acceptability of computed tomographic (CT) colonography and flexible sigmoidoscopy (FS) screening and the factors predicting CT colonographic screening participation, targeting participants in a randomized screening trial. Materials and Methods Eligible individuals aged 58 years (n = 1984) living in Turin, Italy, were randomly assigned to be invited to screening for colorectal cancer with FS or CT colonography. After individuals who had died or moved away (n = 28) were excluded, 264 of 976 (27.0%) underwent screening with FS and 298 of 980 (30.4%) underwent CT colonography. All attendees and a sample of CT colonography nonattendees (n = 299) were contacted for a telephone interview 3–6 months after invitation for screening, and screening experience and factors affecting participation were investigated. Odds ratios (ORs) were computed by means of multivariable logistic regression. Results For the telephone interviews, 239 of 264 (90.6%) FS attendees, 237 of 298 (79.5%) CT colonography attendees, and 182 of 299 (60.9%) CT colonography nonattendees responded. The percentage of attendees who would recommend the test to friends or relatives was 99.1% among FS and 93.3% among CT colonography attendees. Discomfort associated with bowel preparation was higher among CT colonography than FS attendees (OR, 2.77; 95% confidence interval [CI]: 1.47, 5.24). CT colonography nonattendees were less likely to be men (OR, 0.36; 95% CI: 0.18, 0.71), retired (OR, 0.31; 95% CI: 0.13, 0.75), to report regular physical activity (OR, 0.37; 95% CI: 0.20, 0.70), or to have read the information leaflet (OR, 0.18; 95% CI: 0.08, 0.41). They were more likely to mention screening-related anxiety (mild: OR, 6.30; 95% CI: 2.48, 15.97; moderate or severe: OR, 3.63; 95% CI: 1.87, 7.04), erroneous beliefs about screening (OR, 32.15; 95% CI: 6.26, 165.19), or having undergone a recent fecal occult blood test (OR, 13.69; 95% CI: 3.66, 51.29). Conclusion CT colonography and FS screening are well accepted, but further reducing the discomfort from bowel preparation may increase CT colonography screening acceptability. Negative attitudes, erroneous beliefs about screening, and organizational barriers are limiting screening uptake; all these factors are modifiable and therefore potentially susceptible to interventions. © RSNA, 2017 Online supplemental material is available for this article.
Nicolas Balamoutoff, Florent Hugonnet, Marc Faraggi, Benjamin Serrano, ,
Published: 1 January 2018
Radiology, Volume 286, pp 160534-270; https://doi.org/10.1148/radiol.2017160534

Abstract:
To compare the accuracy of a single 20-second deep-inspiration breath hold (DIBH) in fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT) to that with conventional free-breathing (FB) whole-body PET/CT for the assessment, characterization, and quantification of lung lesions in terms of the blurring effect of respiratory motion. Institutional review board approval was obtained, and the requirement to obtain informed consent was waived. A preclinical study was performed in a test population of 19 patients to evaluate the feasibility and consistency of DIBH techniques compared with phase-based respiratory gating (PBRG). One hundred fifteen patients with lung lesions were then prospectively included and assessed with FB PET/CT followed by 20-second DIBH PET/CT. Maximum standardized uptake value (SUVmax), peak standardized uptake value (SUVpeak), and number and size of nodules were reported for each acquisition and then compared with findings from histopathologic examination and/or clinical-radiologic follow-up. Statistical analysis was performed with the t test, χ2 test, Pearson correlation coefficient, and receiver operating characteristic analysis. In the test population, data obtained with DIBH PET and PBRG PET showed close correlation (r = 0.94, P< .001 for SUVmax and r = 0.98, P< .001 for SUVpeak). In the clinical population, both SUVmax and SUVpeak were significantly increased with DIBH compared with FB (5.60 ± 4.20 vs 3.11 ± 1.80 and 2.25 ± 1.75 vs 1.71 ± 0.96, respectively; P< .001). A significantly greater number of lung lesions was detected with DIBH PET/CT compared with FB PET/CT (P< .001), with the detection of 70 additional nodules and more accurate coregistration of 84. According to the area under the receiver operating characteristic curve for SUVpeak, DIBH demonstrated a higher level of accuracy than did FB (P = .039). The DIBH PET/CT technique is feasible in routine clinical practice and is more sensitive for quantitative measurements and lesion localization. This technique reduces the blurring effect of respiratory motion, thus improving the diagnostic accuracy for lung nodules. © RSNA, 2017
, , Velly Lionel, Joshua Kornbluth, , , Russell Chabanne, Betty Jean, Habib Benali, , et al.
Radiology, Volume 287, pp 247-255; https://doi.org/10.1148/radiol.2017162161

Abstract:
Purpose To assess whether early brain functional connectivity is associated with functional recovery 1 year after cardiac arrest (CA). Materials and Methods Enrolled in this prospective multicenter cohort were 46 patients who were comatose after CA. Principal outcome was cerebral performance category at 12 months, with favorable outcome (FO) defined as cerebral performance category 1 or 2. All participants underwent multiparametric structural and functional magnetic resonance (MR) imaging less than 4 weeks after CA. Within- and between-network connectivity was measured in dorsal attention network (DAN), default-mode network (DMN), salience network (SN), and executive control network (ECN) by using seed-based analysis of resting-state functional MR imaging data. Structural changes identified with fluid-attenuated inversion recovery and diffusion-weighted imaging sequences were analyzed by using validated morphologic scales. The association between connectivity measures, structural changes, and the principal outcome was explored with multivariable modeling. Results Patients underwent MR imaging a mean 12.6 days ± 5.6 (standard deviation) after CA. At 12 months, 11 patients had an FO. Patients with FO had higher within-DMN connectivity and greater anticorrelation between SN and DMN and between SN and ECN compared with patients with unfavorable outcome, an effect that was maintained after multivariable adjustment. Anticorrelation of SN-DMN predicted outcomes with higher accuracy than fluid-attenuated inversion recovery or diffusion-weighted imaging scores (area under the receiver operating characteristic curves, respectively, 0.88, 0.74, and 0.71). Conclusion MR imaging-based measures of cerebral functional network connectivity obtained in the acute phase of CA were independently associated with FO at 1 year, warranting validation as early markers of long-term recovery potential in patients with anoxic-ischemic encephalopathy. (©) RSNA, 2017.
, Julie B. Guerin, Caterina Giannini, , Lawrence J. Eckel,
RadioGraphics, Volume 37, pp 2164-2180; https://doi.org/10.1148/rg.2017170037

Abstract:
Radiologists play a key role in brain tumor diagnosis and management and must stay abreast of developments in the field to advance patient care and communicate with other health care providers. In 2016, the World Health Organization (WHO) released an update to its brain tumor classification system that included numerous significant changes. Several previously recognized brain tumor diagnoses, such as oligoastrocytoma, primitive neuroectodermal tumor, and gliomatosis cerebri, were redefined or eliminated altogether. Conversely, multiple new entities were recognized, including diffuse leptomeningeal glioneuronal tumor and multinodular and vacuolating tumor of the cerebrum. The glioma category has been significantly reorganized, with several infiltrating gliomas in children and adults now defined by genetic features for the first time. These changes were driven by increased understanding of important genetic factors that directly impact tumorigenesis and influence patient care. The increased emphasis on genetic factors in brain tumor diagnosis has important implications for radiology, as we now have tools that allow us to evaluate some of these alterations directly, such as the identification of 2-hydroxyglutarate within infiltrating gliomas harboring mutations in the genes for the isocitrate dehydrogenases. For other tumors, such as medulloblastoma, imaging can demonstrate characteristic patterns that correlate with particular disease subtypes. The purpose of this article is to review the changes to the WHO brain tumor classification system that are most pertinent to radiologists. ©RSNA, 2017
Alexis Guédon, , , Camille Jousset, , Manoëlle Kossorotof, , , , , et al.
Published: 1 February 2018
Radiology, Volume 286, pp 651-658; https://doi.org/10.1148/radiol.2017170152

Abstract:
To propose and validate a modified pediatric intracerebral hemorrhage (PICH) (mPICH) score and to compare its association with functional outcome to that of the original PICH score. Data from prospectively included patients were retrospectively analyzed. Consecutive patients with nontraumatic PICH who had undergone clinical follow-up were included. The study population was divided into a development cohort (2008–2012, n = 100) and a validation cohort (2013–2016, n = 43). An mPICH score was developed after variables associated with poor outcome were identified at multivariate analysis (King’s Outcome Scale for Childhood Head Injury score < 5a) in the development cohort. The accuracy of the score for prediction of poor outcome was evaluated (sensitivity, specificity). Discrimination and calibration of associations between the mPICH score and poor outcome cohorts were assessed (C statistics, Hosmer-Lemeshow test). The mPICH score assessed as follows: brain herniation, four points; altered mental status, three points; hydrocephalus, two points; infratentorial PICH, two points; intraventricular hemorrhage, one point; PICH volume greater than 2% of total brain volume, one point. An mPICH score greater than 5 was associated with severe disability or worse, with sensitivity of 97% (95% confidence interval [CI]: 83%, 100%) and specificity of 61% (95% CI: 49%, 73%). The C statistic was 0.81 (95% CI: 0.73, 0.89). In the validation cohort, sensitivity and specificity were 95.2% (95% CI: 76%, 99%) and 77% (95% CI: 55%, 92%), respectively. There was no significant difference between the observed and predicted risks of poor outcome (P = .46). An mPICH score was developed as a simple clinical and imaging grading scale for acute prognosis in patients with PICH. © RSNA, 2017
Seung Pil Ban, , Hyoung Soo Byoun, , Si Un Lee, Jae Seung Bang, Jung Ho Han, , O-Ki Kwon,
Radiology, Volume 286, pp 992-999; https://doi.org/10.1148/radiol.2017170053

Abstract:
To evaluate the effect of middle meningeal artery (MMA) embolization on chronic subdural hematoma (CSDH) and compare the treatment outcomes of MMA embolization and conventional treatment. All consecutive patients 20 years or older with CSDH were assessed for eligibility. CSDHs with a focal location, a thickness of 10 mm or less, no mass effect, or underlying conditions were excluded. Seventy-two prospectively enrolled patients with CSDH underwent MMA embolization (embolization group; as the sole treatment in 27 [37.5%] asymptomatic patients and with additional hematoma removal for symptom relief in 45 [62.5%] symptomatic patients). For comparison, 469 patients who underwent conventional treatment were included as a historical control group (conventional treatment group; close, nonsurgical follow-up in 67 [14.3%] and hematoma removal in 402 [85.7%] patients). Primary outcome was treatment failure defined as a composite of incomplete hematoma resolution (remaining or reaccumulated hematoma with thickness > 10 mm) or surgical rescue (hematoma removal for relief of symptoms that developed with continuous growth of initial or reaccumulated hematoma). Secondary outcomes included surgical rescue as a component of the primary outcome and treatment-related complication for safety measure. Six-month outcomes were compared between the study groups with logistic regression analysis. Spontaneous hematoma resolution was achieved in all of 27 asymptomatic patients undergoing embolization without direct hematoma removal. Hematoma reaccumulation occurred in one (2.2%) of 45 symptomatic patients receiving embolization with additional hematoma removal. Treatment failure rate in the embolization group was lower than in the conventional treatment group (one of 72 patients [1.4%] vs 129 of 469 patients [27.5%], respectively; adjusted odds ratio [OR], 0.056; 95% confidence interval [CI]: 0.011, 0.286; P = .001). Surgical rescue was less frequent in the embolization group (one of 72 patients [1.4%] vs 88 of 469 patients [18.8%]; adjusted OR, 0.094; 95% CI: 0.018, 0.488; P = .005). Treatment-related complication rate was not different between the two groups (0 of 72 patients vs 20 of 469 patients [4.3%]; adjusted OR, 0.145; 95% CI: 0.009, 2.469; P = .182). MMA embolization has a positive therapeutic effect on CSDH and is more effective than conventional treatment. © RSNA, 2017
, Neige Journy, , Michele M. Doody, Bruce H. Alexander, Martha S. Linet, Cari M. Kitahara
Published: 1 February 2018
Radiology, Volume 286, pp 592-601; https://doi.org/10.1148/radiol.2017170683

Abstract:
Purpose To estimate the risk of cataract in a cohort of nuclear medicine (NM) radiologic technologists on the basis of their work histories and radiation protection practices. Materials and Methods In the years 2003—2005 and 2012—2013, 42 545 radiologic technologists from a U.S. prospective study completed questionnaires in which they provided information regarding their work histories and cataract histories. Cox proportional hazards models, stratified according to birth-year cohort (born before 1940 or born in 1940 or later) and adjusted for age, sex, and race, were used to estimate hazard ratios (HRs) for the risk of cataract in radiologic technologists according to NM work history practices according to decade. Results During the follow-up period (mean follow-up, 7½ years), 7137 incident cataracts were reported. A significantly increased risk of cataract (HR, 1.08; 95% confidence interval [CI]: 1.03, 1.14) was observed among workers who performed an NM procedure at least once—as opposed to never. Risks of cataract were increased in the group who had performed a diagnostic (HR, 1.07; 95% CI: 1.01, 1.12) or therapeutic (HR, 1.10; 95% CI: 1.04, 1.17) NM procedure. Risks were higher for those who had first performed diagnostic NM procedures in the 1980s to early 2000s (HR, 1.30; 95% CI: 1.08, 1.58) and those who had performed therapeutic NM procedures in the 1970s (HR, 1.11; 95% CI: 1.01, 1.23) and in the 1980s to early 2000s (HR, 1.14; 95% CI: 1.02, 1.29). With the exception of a significantly increased risk associated with performing therapeutic NM procedures without shielding the radiation source in the 1980s (HR, 1.32; 95% CI: 1.04, 1.67), analyses revealed no association between cataract risk and specific radiation protection technique used. Conclusion An increased risk of cataract was observed among U.S. radiologic technologists who had performed an NM procedure at least once. This association should be examined in future studies incorporating estimated lens doses. © RSNA, 2017
Lu-Yao Zhou, Shu-Ling Chen, Hua-Dong Chen, Yang Huang, Yu-Xin Qiu, , Xiao-Yan Xie
Radiology, Volume 286, pp 1033-1039; https://doi.org/10.1148/radiol.2017170173

Abstract:
Purpose To evaluate the feasibility of ultrasonographically (US) guided percutaneous cholecystocholangiography (PCC) for early exclusion of biliary atresia (BA) in infants suspected of having BA with equivocal US findings or indeterminate type of BA and a gallbladder longer than 1.5 cm at US. Materials and Methods This study was approved by the ethics committee; written informed parental consent was obtained. From February 2016 to December 2016, nine infants (four boys, five girls; mean age, 60.2 days; median age, 57 days; age range, 23–117 days) with conjugated hyperbilirubinemia and gallbladder longer than 1.5 cm at US were referred for US-guided PCC after US findings were equivocal for BA (n = 7) or the type of BA was unclear (n = 2). PCC was performed with a US machine with incorporated contrast pulse sequencing, contrast-specific software, and a linear transducer by injecting diluted contrast material via an 18-gauge needle. Images from US and US-guided PCC were evaluated in consensus by two radiologists. US criteria for BA were fibrotic cord sign (>2 mm) and gallbladder length-to-width ratio greater than 5.2. BA was excluded at PCC when contrast material was visualized in the gallbladder, common hepatic ducts, and common bile duct and during passage to the duodenum. Patients in whom BA was diagnosed after PCC underwent surgery or liver biopsy as the reference standard. Nonparametric and Fisher exact tests were used. Results US-guided PCC was successful in all patients. There were no procedural-related complications. BA was excluded in five of the nine patients. The median serum direct bilirubin level in these patients slightly decreased 1 week after PCC, from 91.1 μmol/L (interquartile range [IQR], 81.6–113.8 μmol/L) to 65.3 μmol/L (IQR, 57.8–74.7 μmol/L); however, this difference was not statistically significant (P = .062). BA was diagnosed in four patients, with the diagnosis confirmed at surgery (n = 2) or liver biopsy (n = 2). BA in two patients with unclear type of BA was defined as type III without patency of the common bile duct in one patient and as type III with patency of the common bile duct in the other. Conclusion In this highly selected group of infants with indeterminate type of BA or inconclusive US findings, US-guided PCC enabled the diagnosis of BA in four infants and the exclusion of BA in five. US-guided PCC may be a safe and effective tool to exclude BA early in infants with equivocal US findings. © RSNA, 2017
, Yoshiko Ueno, Romuald Ferré, Ellen Kao, Anne-Sophie Jannot, Jaron Chong, Atilla Omeroglu, Benoît Mesurolle, Caroline Reinhold, Benoit Gallix
Published: 1 February 2018
Radiology, Volume 286, pp 412-420; https://doi.org/10.1148/radiol.2017170143

Abstract:
Purpose To evaluate whether features from texture analysis of breast cancers were associated with pathologic complete response (pCR) after neoadjuvant chemotherapy and to explore the association between texture features and tumor subtypes at pretreatment magnetic resonance (MR) imaging. Materials and Methods Institutional review board approval was obtained. This retrospective study included 85 patients with 85 breast cancers who underwent breast MR imaging before neoadjuvant chemotherapy between April 10, 2008, and March 12, 2015. Two-dimensional texture analysis was performed by using software at T2-weighted MR imaging and contrast material–enhanced T1-weighted MR imaging. Quantitative parameters were compared between patients with pCR and those with non-pCR and between patients with triple-negative breast cancer and those with non–triple-negative cancer. Multiple logistic regression analysis was used to determine independent parameters. Results Eighteen tumors (22%) were triple-negative breast cancers. pCR was achieved in 30 of the 85 tumors (35%). At univariate analysis, mean pixel intensity with spatial scaling factor (SSF) of 2 and 4 on T2-weighted images and kurtosis on contrast-enhanced T1-weighted images showed a significant difference between triple-negative breast cancer and non–triple-negative breast cancer (P = .009, .003, and .001, respectively). Kurtosis (SSF, 2) on T2-weighted images showed a significant difference between pCR and non-pCR (P = .015). At multiple logistic regression, kurtosis on T2-weighted images was independently associated with pCR in non–triple-negative breast cancer (P = .033). A multivariate model incorporating T2-weighted and contrast-enhanced T1-weighted kurtosis showed good performance for the identification of triple-negative breast cancer (area under the receiver operating characteristic curve, 0.834). Conclusion At pretreatment MR imaging, kurtosis appears to be associated with pCR to neoadjuvant chemotherapy in non–triple-negative breast cancer and may be a promising biomarker for the identification of triple-negative breast cancer. © RSNA, 2017
, Kyle R. Noll, , Sujit S. Prabhu, Yuan-Hsiung Tsai, Sheng-Wei Chang, , Jiann-Der Lee, Jen-Tsung Yang, , et al.
Published: 1 February 2018
Radiology, Volume 286, pp 512-523; https://doi.org/10.1148/radiol.2017162971

Abstract:
To compare functional magnetic resonance (MR) imaging for language mapping (hereafter, language functional MR imaging) with direct cortical stimulation (DCS) in patients with brain tumors and to assess factors associated with its accuracy. PubMed/MEDLINE and related databases were searched for research articles published between January 2000 and September 2016. Findings were pooled by using bivariate random-effects and hierarchic summary receiver operating characteristic curve models. Meta-regression and subgroup analyses were performed to evaluate whether publication year, functional MR imaging paradigm, magnetic field strength, statistical threshold, and analysis software affected classification accuracy. Ten articles with a total of 214 patients were included in the analysis. On a per-patient basis, the pooled sensitivity and specificity of functional MR imaging was 44% (95% confidence interval [CI]: 14%, 78%) and 80% (95% CI: 54%, 93%), respectively. On a per-tag basis (ie, each DCS stimulation site or “tag” was considered a separate data point across all patients), the pooled sensitivity and specificity were 67% (95% CI: 51%, 80%) and 55% (95% CI: 25%, 82%), respectively. The per-tag analysis showed significantly higher sensitivity for studies with shorter functional MR imaging session times (P = .03) and relaxed statistical threshold (P = .05). Significantly higher specificity was found when expressive language task (P = .02), longer functional MR imaging session times (P< .01), visual presentation of stimuli (P = .04), and stringent statistical threshold (P = .01) were used. Results of this study showed moderate accuracy of language functional MR imaging when compared with intraoperative DCS, and the included studies displayed significant methodologic heterogeneity. © RSNA, 2017 Online supplemental material is available for this article.
, Teri M. Sippel Schmidt, Christopher D. Carr,
RadioGraphics, Volume 37, pp 2106-2112; https://doi.org/10.1148/rg.2017160106

Abstract:
Currently, most radiology reports are highly variable and consist of unconstrained narrative text. This variability limits the ability to extract information from the report to guide clinical care, populate a data registry, or support quality improvement. This article introduces two newly available standards that pertain to radiology reports. Management of Radiology Reporting Templates (MRRT) is an integration profile that defines the format and exchange mechanisms for radiology report templates. Digital Imaging and Communications in Medicine Part 20 defines how reports built using MRRT-based templates can be transmitted into an electronic health record (EHR). Together, these two standards enable new ways to improve report consistency and completeness, ensure proper clinical action, and improve the quality of patient care. Commercial and open-source developers are beginning to incorporate these standards into clinical systems. The authors use an example of a patient with an incidentally detected lung nodule to illustrate how these standards improve the exchange of information. The clinical scenario follows the use of the appropriate template through the completion of the radiology report, with the incidental finding structured and coded to enable automated follow-up in the EHR. ©RSNA, 2017
, Till F. Kaireit, Andreas Voskrebenzev, , Julia Freise, , , ,
Radiology, Volume 286, pp 1040-1051; https://doi.org/10.1148/radiol.2017170591

Abstract:
To quantify regional lung ventilation in patients with chronic obstructive pulmonary disease (COPD) by using free-breathing dynamic fluorinated (fluorine 19 [19F]) gas magnetic resonance (MR) imaging. In this institutional review board–approved prospective study, 27 patients with COPD were examined by using breath-hold 19F gas wash-in MR imaging during inhalation of a normoxic fluorinated gas mixture (perfluoropropane) and by using free-breathing dynamic 19F gas washout MR imaging after inhalation of the gas mixture was finished for a total of 25–30 L. Regional lung ventilation was quantified by using volume defect percentage (VDP), washout time, number of breaths, and fractional ventilation (FV). To compare different lung function parameters, Pearson correlation coefficient and Fisher z transformation were used, which were corrected for multiple comparisons with the Bonferroni method. Statistically significant correlations were observed for all evaluated lung function test parameters compared with median and interquartile range of 19F washout parameters. An inverse linear correlation of median number of breaths (r = −0.82; P< .0001) and median washout times (r = −0.77; P< .0001) with percentage predicted of forced expiratory volume in 1 second (FEV1) was observed; correspondingly median FV (r = 0.86; P< .0001) correlated positively with percentage predicted FEV1. Comparing initial with late phase, median VDP of all subjects decreased from 49% (25th–75th percentile, 35%–62%) to 6% (25th–75th percentile, 2%–10%; P< .0001). VDP at the beginning of the gas wash-in phase (VDPinitial) significantly correlated with percentage predicted FEV1 (r = −0.74; P = .0028) and FV (r = 0.74; P = .0002). Median FV was significantly increased in ventilated regions (11.1% [25th–75th percentile, 6.8%–14.5%]) compared with the defect regions identified by VDPinitial (5.8% [25th–75th percentile, 4.0%–7.4%]; P< .0001). Quantification of regional lung ventilation by using dynamic 19F gas washout MR imaging in free breathing is feasible at 1.5 T even in obstructed lung segments. © RSNA, 2017 Online supplemental material is available for this article.
Christian Tesche, , Moritz H. Albrecht, Taylor M. Duguay, Richard R. Bayer, Sheldon E. Litwin, Daniel H. Steinberg,
Published: 1 October 2017
Radiology, Volume 285, pp 17-33; https://doi.org/10.1148/radiol.2017162641

Abstract:
Invasive coronary angiography (ICA) with measurement of fractional flow reserve (FFR) by means of a pressure wire technique is the established reference standard for the functional assessment of coronary artery disease (CAD) ( 1 , 2 ). Coronary computed tomographic (CT) angiography has emerged as a noninvasive method for direct assessment of CAD and plaque characterization with high diagnostic accuracy compared with ICA ( 3 , 4 ). However, the solely anatomic assessment provided with both coronary CT angiography and ICA has poor discriminatory power for ischemia-inducing lesions. FFR derived from standard coronary CT angiography (FFRCT) data sets by using any of several advanced computational analytic approaches enables combined anatomic and hemodynamic assessment of a coronary lesion by a single noninvasive test. Current technical approaches to the calculation of FFRCT include algorithms based on full- and reduced-order computational fluid dynamic modeling, as well as artificial intelligence deep machine learning ( 5 , 6 ). A growing body of evidence has validated the diagnostic accuracy of FFRCT techniques compared with invasive FFR. Improved therapeutic guidance has been demonstrated, showing the potential of FFRCT to streamline and rationalize the care of patients suspected of having CAD and improve outcomes while reducing overall health care costs ( 7 , 8 ). The purpose of this review is to describe the scientific principles, clinical validation, and implementation of various FFRCT approaches, their precursors, and related imaging tests. © RSNA, 2017.
Published: 1 October 2017
Radiology, Volume 285, pp 3-11; https://doi.org/10.1148/radiol.2017170798

Abstract:
This Annual Oration considers the transformation of American health care from a fee-for-service system to a value-based system and how imaging can advance value and enhance the transformation to higher quality, better care, and improved outcomes.
Judy Wu, Carina Yang, John Collins,
Published: 1 October 2017
Radiology, Volume 285, pp 319-323; https://doi.org/10.1148/radiol.2017151645

Aditi Shruti,
Published: 1 October 2017
Radiology, Volume 285, pp 324-328; https://doi.org/10.1148/radiol.2017132069

Abstract:
HistoryA 6-day-old female neonate presented to the outpatient pediatric surgery clinic for evaluation of a possible prenatal abdominal mass. The neonate was delivered at term via cesarean section due to macrosomia, with a reported birth weight of 11 lb 8.7 oz (5.23 kg). The patient’s postnatal course was remarkable for resolving neonatal hyperbilirubinemia. A physical examination was remarkable for a palpable mass in the abdomen. Maternal risk factors included class II obesity, type 2 diabetes, and metabolic syndrome.Prenatal images obtained at an outside institution were not available at this time. Ultrasonography (US) of the abdomen and pelvis was performed 6 days after birth. Follow-up US at 29 days of life revealed no substantial change in the appearance of the findings.This patient remained asymptomatic, and gadolinium-enhanced (Magnevist; Bayer Pharma, Berlin, Germany) magnetic resonance (MR) imaging of the abdomen and pelvis was performed at 84 days of life.The mass was excised surgically at 89 days of life, and the patient had an uncomplicated postoperative course.
, , Bernhard Strasser, Patrik Krumpolec, Petra Hnilicová, , Philipp A. Moser, Ovidiu C. Andronesi, Andre J. Van Der Kouwe, Peter Valkovic, et al.
Published: 1 February 2018
Radiology, Volume 286, pp 666-675; https://doi.org/10.1148/radiol.2017170744

Abstract:
Purpose To compare the involuntary head motion, frequency and B0 shim changes, and effects on data quality during real-time–corrected three-dimensional γ-aminobutyric acid−edited magnetic resonance (MR) spectroscopic imaging in subjects with mild cognitive impairment (MCI), patients with Parkinson disease (PD), and young and older healthy volunteers. Materials and Methods In this prospective study, MR spectroscopic imaging datasets were acquired at 3 T after written informed consent was obtained. Translational and rotational head movement, frequency, and B0 shim were determined with an integrated volumetric navigator. Head motion patterns and imager instability were investigated in 33 young healthy control subjects (mean age ± standard deviation, 31 years ± 5), 34 older healthy control subjects (mean age, 67 years ± 8), 34 subjects with MCI (mean age, 72 years ± 5), and 44 patients with PD (mean age, 64 years ± 8). Spectral quality was assessed by means of region-of-interest analysis. Group differences were evaluated with Bonferroni-corrected Mann-Whitney tests. Results Three patients with PD and four subjects with MCI were excluded because of excessive head motion (ie, > 0.8 mm translation per repetition time of 1.6 seconds throughout >10 minutes). Older control subjects, patients with PD, and subjects with MCI demonstrated 1.5, 2, and 2.5 times stronger head movement, respectively, than did young control subjects (1.79 mm ± 0.77) (P< .001). Of young control subjects, older control subjects, patients with PD, and subjects with MCI, 6%, 35%, 38%, and 51%, respectively, moved more than 3 mm during the MR spectroscopic imaging acquisition of approximately 20 minutes. The predominant movements were head nodding and “sliding out” of the imager. Frequency changes were 1.1- and 1.4-fold higher in patients with PD (P = .007) and subjects with MCI (P< .001), respectively, and B0 shim changes were 1.3-, 1.5-, and 1.9-fold higher in older control subjects (P = .005), patients with PD (P< .001), and patients with MCI (P< .001), respectively, compared with those of young control subjects (12.59 Hz ± 2.49, 3.61 Hz · cm−1 ± 1.25). Real-time correction provided high spectral quality in all four groups (signal-to-noise ratio >15, Cramér-Rao lower bounds < 20%). Conclusion Real-time motion and B0 monitoring provides valuable information about motion patterns and B0 field variations in subjects with different predispositions for head movement. Immediate correction improves data quality, particularly in patients who have difficulty avoiding movement. © RSNA, 2017 Online supplemental material is available for this article.
Published: 1 December 2017
Radiology, Volume 285, pp 896-903; https://doi.org/10.1148/radiol.2017170438

Abstract:
To gain more insight into the pathophysiological mechanisms of visual hallucinations (VHs) in patients with Parkinson disease (PD) by analyzing whole-brain resting-state functional connectivity in PD patients with VH (hereafter, referred to as PD + VH patients) and without VH (hereafter, referred to as PD − VH patients) and control participants. For this retrospective study, 15 PD + VH patients, 40 PD − VH patients, and 15 control participants from a prospective cohort study were included, which was approved by the local ethics board and written informed consent was obtained from all participants. Functional connectivity was calculated between 47 regions of interests, of which whole-brain and region-specific means were compared by using a general linear model with false discovery rate control for multiple comparisons. Whole-brain mean functional connectivity was significantly lower in PD patients compared with control participants, with regional decreases involving paracentral and occipital regions in both PD + VH and PD − VH patients (mean whole-brain functional connectivity in PD + VH vs PD − VH, 0.12 ± 0.01 [standard deviation] vs 0.14 ± 0.03, respectively; control participants, 0.15 ± 0.04; P< .05, corrected). In PD + VH patients, nine additional frontal, temporal, occipital, and striatal regions showed decreased functional connectivity compared with control participants (mean of these nine regions in PD + VH, PD − VH, and control participants: 0.12 ± 0.02, 0.14 ± 0.03, and 0.16 ± 0.04, respectively; P< .05, corrected). Resting-state functional connectivity was unrelated to motor performance (r = 0.182; P = .184) and related to cognitive deficits such as attention and perception (ρ, −0.555 and −0.558, respectively; P< .05). The findings show a PD-related effect on resting-state functional connectivity of posterior and paracentral brain regions, whereas the presence of VH is associated with a more global loss of connectivity, related to attention and perception. These findings suggest that the pathophysiological mechanisms of VH in PD may include a global loss of network efficiency, which could drive disturbed attentional and visual processing. © RSNA, 2017 Online supplemental material is available for this article.
Wen-Tao Wang, Li Yang, Zhao-Xia Yang, Xin-Xing Hu, Ying Ding, Xu Yan, Cai-Xia Fu, , ,
Published: 1 February 2018
Radiology, Volume 286, pp 571-580; https://doi.org/10.1148/radiol.2017170515

Abstract:
Purpose To evaluate the potential role of diffusion kurtosis imaging and conventional magnetic resonance (MR) imaging findings including standard monoexponential model of diffusion-weighted imaging and morphologic features for preoperative prediction of microvascular invasion (MVI) of hepatocellular carcinoma (HCC). Materials and Methods Institutional review board approval and written informed consent were obtained. Between September 2015 and November 2016, 84 patients (median age, 54 years; range, 29–79 years) with 92 histopathologically confirmed HCCs (40 MVI-positive lesions and 52 MVI-negative lesions) were analyzed. Preoperative MR imaging examinations including diffusion kurtosis imaging (b values: 0, 200, 500, 1000, 1500, and 2000 sec/mm2) were performed and kurtosis, diffusivity, and apparent diffusion coefficient maps were calculated. Morphologic features of conventional MR images were also evaluated. Univariate and multivariate logistic regression analyses were used to evaluate the relative value of these parameters as potential predictors of MVI. Results Features significantly related to MVI of HCC at univariate analysis were increased mean kurtosis value (P< .001), decreased mean diffusivity value (P = .033) and apparent diffusion coefficient value (P = .011), and presence of infiltrative border with irregular shape (P = .005) and irregular circumferential enhancement (P = .026). At multivariate analysis, mean kurtosis value (odds ratio, 6.25; P = .001), as well as irregular circumferential enhancement (odds ratio, 6.92; P = .046), were independent risk factors for MVI of HCC. The mean kurtosis value for MVI of HCC showed an area under the receiver operating characteristic curve of 0.784 (optimal cutoff value was 0.917). Conclusion Higher mean kurtosis values in combination with irregular circumferential enhancement are potential predictive biomarkers for MVI of HCC. © RSNA, 2017
Published: 1 February 2018
Radiology, Volume 286, pp 705-714; https://doi.org/10.1148/radiol.2017170241

Abstract:
To evaluate the clinical performance of dual-agent relaxation contrast (DARC) magnetic resonance (MR) lymphangiography compared with that of conventional MR lymphangiography in the creation of isolated lymphatic maps in patients with secondary lymphedema. This retrospective study was approved by the institutional review board. The diagnostic quality of 42 DARC MR lymphangiographic studies was compared with that of 42 conventional MR lymphangiographic studies. Two independent readers rated venous contamination as absent, mild, or moderate to severe. Interreader agreement on venous contamination grades was assessed by using the linearly weighted Cohen κ statistic. The Mann-Whitney U test was used to compare the distribution of grades at each station between conventional MR lymphangiography and DARC MR lymphangiography for each reader separately. DARC MR lymphangiography had significantly less venous contamination than did conventional MR lymphangiography (P< .001). The two radiologists rated venous contamination as moderate to severe in 64% (27 of 42) and 69% (29 of 42) of distal limbs, 23% (10 of 42) of midlimbs, and 2% (one of 42) and 9% (four of 42) of proximal limbs at conventional MR lymphangiography compared with 0% (0 of 42) of distal limbs, 2% (one of 42) of midlimbs, and 0% (0 of 42) of proximal limbs at DARC MR lymphangiography. Lymphatic signal was partially attenuated (median 45% decrease) when longer echo times were used for venous suppression, but it did not subjectively degrade diagnostic quality. DARC MR lymphangiography yields isolated lymphatic maps through nulling of venous contamination, thereby simplifying diagnostic interpretation and communication with surgical colleagues. © RSNA, 2017
, , Richard Kijowski, Tyler Bradshaw, Alan B. McMillan
Published: 1 February 2018
Radiology, Volume 286, pp 676-684; https://doi.org/10.1148/radiol.2017170700

Abstract:
To develop and evaluate the feasibility of deep learning approaches for magnetic resonance (MR) imaging–based attenuation correction (AC) (termed deep MRAC) in brain positron emission tomography (PET)/MR imaging. A PET/MR imaging AC pipeline was built by using a deep learning approach to generate pseudo computed tomographic (CT) scans from MR images. A deep convolutional auto-encoder network was trained to identify air, bone, and soft tissue in volumetric head MR images coregistered to CT data for training. A set of 30 retrospective three-dimensional T1-weighted head images was used to train the model, which was then evaluated in 10 patients by comparing the generated pseudo CT scan to an acquired CT scan. A prospective study was carried out for utilizing simultaneous PET/MR imaging for five subjects by using the proposed approach. Analysis of covariance and paired-sample t tests were used for statistical analysis to compare PET reconstruction error with deep MRAC and two existing MR imaging–based AC approaches with CT-based AC. Deep MRAC provides an accurate pseudo CT scan with a mean Dice coefficient of 0.971 ± 0.005 for air, 0.936 ± 0.011 for soft tissue, and 0.803 ± 0.021 for bone. Furthermore, deep MRAC provides good PET results, with average errors of less than 1% in most brain regions. Significantly lower PET reconstruction errors were realized with deep MRAC (−0.7% ± 1.1) compared with Dixon-based soft-tissue and air segmentation (−5.8% ± 3.1) and anatomic CT-based template registration (−4.8% ± 2.2). The authors developed an automated approach that allows generation of discrete-valued pseudo CT scans (soft tissue, bone, and air) from a single high-spatial-resolution diagnostic-quality three-dimensional MR image and evaluated it in brain PET/MR imaging. This deep learning approach for MR imaging–based AC provided reduced PET reconstruction error relative to a CT-based standard within the brain compared with current MR imaging–based AC approaches. © RSNA, 2017 Online supplemental material is available for this article.
, Loek Pieter Smits, , Annekatrien Depla, Sjoerd Douwe Kuiken, Bert Cornelis Baak, Aart Johannes Nederveen, ,
Published: 1 February 2018
Radiology, Volume 286, pp 547-556; https://doi.org/10.1148/radiol.2017162931

Abstract:
To prospectively compare the diagnostic accuracy of controlled attenuation parameter (CAP) obtained with transient elastography and proton density fat fraction (PDFF) obtained with proton magnetic resonance (MR) spectroscopy with results of liver biopsy in a cohort of adult patients suspected of having nonalcoholic fatty liver disease (NAFLD). The institutional review board approved this study. Informed consent was obtained from all patients. The authors evaluated 55 patients suspected of having NAFLD (40 men, 15 women). Patients had a median age of 52.3 years (interquartile range [IQR], 43.7–57.6 years) and a median body mass index of 27.8 kg/m2 (IQR, 26.0–33.1 kg/m2). CAP and PDFF measurements were obtained on the same day, within 27 days of biopsy (IQR, 7–44 days). CAP and PDFF were compared between steatosis grades by using the Jonckheere-Terpstra test. Diagnostic accuracies of CAP and PDFF for grading steatosis were assessed with receiver operating characteristic (ROC) analysis. Within-weeks reproducibility (CAP and PDFF) and within-session repeatability were assessed with linear regression analyses, intraclass correlation coefficients, and coefficients of variation. Steatosis grades at liver biopsy were distributed as follows: S0, five patients; S1, 24 patients; S2, 17 patients; and S3, nine patients. Both PDFF and CAP helped detect histologically proven steatosis (≥S1), but PDFF showed better diagnostic accuracy than CAP in terms of the area under the ROC curve (0.99 vs 0.77, respectively; P = .0334). PDFF, but not CAP, enabled the grading of steatosis (P< .0001). For within-weeks reproducibility, the intraclass correlation coefficient with PDFF was higher than that with CAP (0.95 vs 0.65, respectively; P = .0015); coefficients of variation were similar (19% vs 11%, P = .55). Within-session repeatability of CAP was good, with a coefficient of variation of 4.5%. MR spectroscopy–derived PDFF is superior to CAP in detecting and grading liver steatosis in human NAFLD. © RSNA, 2017 Online supplemental material is available for this article.
Jing Luo, Brian S. Johnston, Averi E. Kitsch, Daniel S. Hippe, Larissa A. Korde, Sara Javid, Janie M. Lee, Sue Peacock, Constance D. Lehman, Savannah C. Partridge, et al.
Published: 1 December 2017
Radiology, Volume 285, pp 788-797; https://doi.org/10.1148/radiol.2017170587

Abstract:
To investigate whether specific imaging features on breast magnetic resonance (MR) images are associated with ductal carcinoma in situ (DCIS) recurrence risk after definitive treatment. Patients with DCIS who underwent preoperative dynamic contrast material–enhanced (DCE) MR imaging between 2004 and 2014 with ipsilateral recurrence more than 6 months after definitive surgical treatment were retrospectively identified. For each patient, a control subject with DCIS that did not recur was identified and matched on the basis of clinical, histopathologic, and treatment features known to affect recurrence risk. On DCE MR images, lesion characteristics (longest diameter, functional tumor volume [FTV], peak percentage enhancement [PE], peak signal enhancement ratio [SER], and washout fraction) and normal tissue features (background parenchymal enhancement [BPE] volume, mean BPE) were quantitatively measured. MR imaging features were compared between patients and control subjects by using the Wilcoxon signed-rank test, with adjustment for multiple comparisons. Of 415 subjects with DCIS who underwent preoperative MR imaging, 14 experienced recurrence and 11 had an identifiable matching control subject (final cohort, 11 patients and 11 control subjects). Median time to recurrence was 14 months, and median follow-up for control subjects was 102 months. When compared with matched control subjects, patients with DCIS recurrence exhibited significantly greater FTV (median, 9.3 cm3 vs 1.3 cm3, P = .01), lesion peak SER (median, 1.7 vs 1.2; P = .03), and mean BPE (median, 58.3% vs 41.1%; P = .02). Quantitative lesion and normal breast tissue characteristics at preoperative MR imaging in women with newly diagnosed DCIS show promise for association with breast cancer recurrence after treatment. © RSNA, 2017
, Robert M. Judd, Raymond J. Kim, Han W. Kim, Igor Klem, John F. Heitner, Dipan J. Shah, Jennifer Jue,
Published: 1 February 2018
Radiology, Volume 286, pp 452-460; https://doi.org/10.1148/radiol.2017170529

Abstract:
To evaluate the prognostic value of a simple index of left ventricular (LV) long-axis function—lateral mitral annular plane systolic excursion (MAPSE)—in a large multicenter population of patients with reduced ejection fraction (EF) who were undergoing cardiac magnetic resonance (MR) imaging. This retrospective study included 1040 consecutive patients (mean age, 59.5 years ± 15.8) at four U.S. medical centers who were undergoing cardiac MR imaging for assessment of LV dysfunction with EF less than 50%. Lateral MAPSE was measured in the four-chamber cine view. The primary end point was all-cause death. Cox proportional hazards regression modeling was used to examine the independent association between lateral MAPSE and death. The incremental prognostic value of lateral MAPSE was assessed in nested models. During a median follow-up of 4.4 years, 132 patients died. With Kaplan-Meier analysis, the risk of death increased significantly with decreasing tertiles of lateral MAPSE (log-rank P = .0001). Patients with relatively preserved lateral MAPSE (>9 mm) had very few deaths, regardless of whether their EF was above or below 35%. Patients with late gadolinium enhancement (LGE) and low lateral MAPSE had significantly reduced survival compared to those with LGE and high lateral MAPSE (log-rank P< .0001). Lateral MAPSE was independently associated with risk of death after adjustment for clinical and imaging risk factors, which were univariate predictors (age, body mass index, diabetes, LV end-diastolic volume index, LGE, EF) (hazard ratio = 2.051 per mm decrease; 95% confidence interval [CI]: 1.520, 2.768; P< .001). Inclusion of lateral MAPSE in this model resulted in significant improvement in model fit (likelihood ratio test P< .0001) and C statistic (increasing from 0.675 to 0.844; P< .0001). Continuous net reclassification improvement was 1.036 (95% CI: 0.878, 1.194). Lateral MAPSE measured during routine cine cardiac MR imaging is a significant independent predictor of mortality in patients with LV dysfunction, incremental to common clinical and cardiac MR risk factors—including EF and LGE. © RSNA, 2017
Published: 1 January 2018
Radiology, Volume 286, pp 162139-204; https://doi.org/10.1148/radiol.2017162139

Abstract:
To evaluate the rate of malignancy in incidentally detected simple adnexal cysts at computed tomography (CT) to determine if simple-appearing cysts require follow-up. In this HIPAA-compliant, institutional review board–approved retrospective cohort study, an institutional database was searched for abdominal and pelvic CT studies performed between June 2003 and December 2010 in women reported to have adnexal cysts. Adnexal cyst characterization was determined by prospective report description as well as image review by a research fellow and by a fellowship-trained abdominal radiologist for examinations with disagreement between the original report and the research fellow’s assessment. Patients with known ovarian cysts or ovarian cancer at time of the index CT examination were excluded. Clinical outcome was assessed by using follow-up imaging studies, medical records, and the state cancer registry. Benign outcome was determined by benign findings at surgery, a decrease in size or resolution of a simple-appearing cyst at follow-up imaging, or stability of the cyst for at least 1 year. Descriptive statistics and 95% confidence intervals (CIs) were calculated. Among 42 111 women who underwent abdominal and pelvic CT examinations in the study period, 2763 (6.6%; 95% CI: 6.3%, 6.8%) (mean age, 48.1 years ± 18.1; range, 15–102 years) had a newly detected finding of ovarian cyst described in the body or impression section of the report. Median cyst size was 3.1 cm (range, 0.8–20.0 cm). Eighteen (0.7%; 95% CI: 0.4%, 1.0%) of 2763 patients were found to have ovarian cancer after an average follow-up of 5.1 years ± 3.8 (range, 0–12.8 years). None (95% CI: 0%, 0.4%) of 1031 women with simple-appearing cysts were given a diagnosis of ovarian cancer. This included none (95% CI: 0%, 0.4%) of 904 women with simple-appearing cysts with an adequate reference standard for benign outcome. The prevalence of previously unknown adnexal cysts at CT was 6.6%, with an ovarian cancer rate of 0.7% (95% CI: 0.4%, 1.0%). All simple-appearing cysts were benign (95% CI: 99.6%, 100%). © RSNA, 2017 Online supplemental material is available for this article.
, Hiroto Hatabu, Lynette M. Sholl, Nikhil H. Ramaiya
RadioGraphics, Volume 37, pp 1371-1387; https://doi.org/10.1148/rg.2017170015

Abstract:
Recent advances in understanding the molecular mechanisms of cancer have opened a new era of precision medicine for cancer treatment. Precision cancer therapies target specific molecules that are responsible for cancer development and progression, and they achieve marked treatment benefits in specific cohorts of patients. However, these therapies are also associated with a variety of complications that are often unique to specific groups of anticancer agents. The rapidly increasing use of immune checkpoint inhibitors in the treatment of various advanced malignancies has brought new challenges in diagnosing and monitoring a unique set of toxic effects termed immune-related adverse events. Familiarity with cutting-edge cancer treatment approaches and awareness of the emerging complications from novel therapies are essential for radiologists, who play a key role in the care of patients with cancer. This article provides a comprehensive review of the thoracic complications of precision cancer therapies, describes their imaging features and clinical characteristics, and discusses the role of radiologists in the diagnosis and monitoring of these entities. The authors also address the molecular mechanisms of anticancer agents that relate to thoracic complications and emphasize emerging challenges in novel cancer therapies. This article is designed to serve as a practical reference guide for day-to-day practice for radiologists in the era of precision cancer medicine. ©RSNA, 2017
David P. Burrowes, Alexandra Medellin, Allison C. Harris, ,
RadioGraphics, Volume 37, pp 1388-1400; https://doi.org/10.1148/rg.2017170034

Abstract:
Focal liver lesions are commonly encountered and often demonstrate nonspecific findings at initial imaging. Although most incidentally discovered liver lesions are benign, their noninvasive diagnosis is necessary, especially if they are large or atypical. Imaging characterization of focal liver lesions and exclusion of malignancy are of prime importance, particularly in high-risk populations. Contrast agent–enhanced ultrasonography of liver lesions is both accurate and reproducible for evaluation of benign and malignant liver tumors. Use of an imaging algorithm and a controlled sonographic technique, including dedicated arterial phase cine imaging and imaging every 30 seconds in the portal venous phase and the delayed (or late) phase, is essential for accurate characterization. This algorithmic analysis of focal liver lesions focuses first on the determination of malignancy by imaging the portal venous phase and the late phase; washout in these phases correlates with a malignant tumor, and sustained enhancement in these phases is suggestive that a lesion is benign. In addition, the timing and the intensity of washout differentiate hepatocellular malignancies from nonhepatocellular malignancies. Nonhepatocellular tumors demonstrate early and strong washout, whereas hepatocellular malignancies show delayed and weak washout. Subsequent analysis of dynamic real-time enhancement patterns in the arterial phase demonstrates specific enhancement patterns of common benign and malignant focal liver lesions. Hemangiomas show classic peripheral nodular enhancement, and spoke-wheel centrifugal enhancement is suggestive of focal nodular hyperplasia. Hepatic adenomas may show centripetal filling. However, arterial phase enhancement in malignancy has less specificity. Online supplemental material is available for this article.©RSNA, 2017 •
Erratum
, Santiago Martínez-Jiménez, Melissa L. Rosado-De-Christenson, Sonia L. Betancourt, Carlos S. Restrepo, Andrés Eraso
RadioGraphics, Volume 37, pp 1607-1607; https://doi.org/10.1148/rg.2017174011

Meir H. Scheinfeld, Daniel A. Krieger, Deepa Bhupali, Richard L. Zampolin, Amichai J. Erdfarb
RadioGraphics, Volume 37, pp 1605-1606; https://doi.org/10.1148/rg.2017160214

Abstract:
This presentation describes the imaging scales and techniques used in the 2015 endovascular stroke trials and the revised 2015 American Heart Association/American Stroke Association guidelines for endovascular stroke treatment.
Takeshi Yokoo, , , Mustafa R. Bashir, , Diego Hernando, , Holger Hetterich, Jens-Peter Kühn, Guido M. Kukuk, et al.
Published: 1 February 2018
Radiology, Volume 286, pp 486-498; https://doi.org/10.1148/radiol.2017170550

Abstract:
Purpose To determine the linearity, bias, and precision of hepatic proton density fat fraction (PDFF) measurements by using magnetic resonance (MR) imaging across different field strengths, imager manufacturers, and reconstruction methods. Materials and Methods This meta-analysis was performed in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. A systematic literature search identified studies that evaluated the linearity and/or bias of hepatic PDFF measurements by using MR imaging (hereafter, MR imaging-PDFF) against PDFF measurements by using colocalized MR spectroscopy (hereafter, MR spectroscopy-PDFF) or the precision of MR imaging-PDFF. The quality of each study was evaluated by using the Quality Assessment of Studies of Diagnostic Accuracy 2 tool. De-identified original data sets from the selected studies were pooled. Linearity was evaluated by using linear regression between MR imaging-PDFF and MR spectroscopy-PDFF measurements. Bias, defined as the mean difference between MR imaging-PDFF and MR spectroscopy-PDFF measurements, was evaluated by using Bland-Altman analysis. Precision, defined as the agreement between repeated MR imaging-PDFF measurements, was evaluated by using a linear mixed-effects model, with field strength, imager manufacturer, reconstruction method, and region of interest as random effects. Results Twenty-three studies (1679 participants) were selected for linearity and bias analyses and 11 studies (425 participants) were selected for precision analyses. MR imaging-PDFF was linear with MR spectroscopy-PDFF (R2 = 0.96). Regression slope (0.97; P < .001) and mean Bland-Altman bias (-0.13%; 95% limits of agreement: -3.95%, 3.40%) indicated minimal underestimation by using MR imaging-PDFF. MR imaging-PDFF was precise at the region-of-interest level, with repeatability and reproducibility coefficients of 2.99% and 4.12%, respectively. Field strength, imager manufacturer, and reconstruction method each had minimal effects on reproducibility. Conclusion MR imaging-PDFF has excellent linearity, bias, and precision across different field strengths, imager manufacturers, and reconstruction methods. © RSNA, 2017 Online supplemental material is available for this article. An earlier incorrect version of this article appeared online. This article was corrected on October 2, 2017.
Published: 1 February 2018
Radiology, Volume 286, pp 537-546; https://doi.org/10.1148/radiol.2017170116

Abstract:
To synthesize two low-molecular-weight iron chelates and compare their T1 contrast effects with those of a commercial gadolinium-based contrast agent for their applicability in dynamic contrast material–enhanced (DCE) magnetic resonance (MR) imaging. The animal experiments were approved by the local ethics committee. Two previously described iron (Fe) chelates of pentetic acid (Fe-DTPA) and of trans-cyclohexane diamine tetraacetic acid (Fe-tCDTA) were synthesized with stability constants several orders of magnitude higher than those of gadolinium-based contrast agents. The T1 contrast effects of the two chelates were compared with those of gadopentetate dimeglumine in blood serum phantoms at 1.5 T, 3 T, and 7 T. For in vivo studies, a human breast cancer cell line (MDA-231) was implanted in five mice per group. The dynamic contrast effects of the chelates were compared by performing DCE MR imaging with intravenous application of Fe-DTPA or Fe-tCDTA on day 1 and DCE MR imaging in the same tumors with gadopentetate dimeglumine on day 2. Quantitative DCE maps were generated with software and were compared by means of a one-tailed Pearson correlation test. Relaxivities in serum (0.94 T at room temperature) of Fe-tCDTA (r1 = 2.2 mmol−1 · sec−1, r2 = 2.5 mmol−1 · sec−1) and Fe-DTPA (r1 = 0.9 mmol−1 · sec−1, r2 = 0.9 mmol−1 · sec−1) were approximately twofold and fivefold lower, respectively, compared with those of gadopentetate dimeglumine (r1 = 4.1 mmol−1 · sec−1, r2 = 4.8 mmol−1 · sec−1). Used at moderately higher concentrations, however, iron chelates generated similar contrast effects at T1-weighted MR imaging in vitro in serum, in vivo in blood, and for DCE MR imaging of breast cancer xenografts. The volume transfer constant values for Fe-DTPA and Fe-tCDTA in the same tumors correlated well with those observed for gadopentetate dimeglumine (Fe-tCDTA Pearson R, 0.99; P = .0003; Fe-DTPA Pearson R, 0.97; P = .003). Iron-based contrast agents are promising as alternatives for contrast enhancement at T1-weighted MR imaging and have the potential to contribute to the safety of MR imaging. © RSNA, 2017 Online supplemental material is available for this article.
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