The MRI‐measured arterial input function resulting from a bolus injection of Gd‐DTPA in a rat model of stroke slightly underestimates that of Gd‐[14C]DTPA and marginally overestimates the blood‐to‐brain influx rate constant determined by Patlak plots
Open Access
- 21 May 2010
- journal article
- research article
- Published by Wiley in Magnetic Resonance in Medicine
- Vol. 63 (6), 1502-1509
- https://doi.org/10.1002/mrm.22339
Abstract
The hypothesis that the arterial input function (AIF) of gadolinium‐diethylenetriaminepentaacetic acid injected by intravenous bolus and measured by the change in the T1‐relaxation rate (ΔR 1; R 1 = 1/T 1) of superior sagittal sinus blood (AIF‐I) approximates the AIF of 14C‐labeled gadolinium‐diethylenetriaminepentaacetic acid measured in arterial blood (reference AIF) was tested in a rat stroke model (n = 13). Contrary to the hypothesis, the initial part of the ΔR1‐time curve was underestimated, and the area under the normalized curve for AIF‐I was about 15% lower than that for the reference AIF. Hypothetical AIFs for gadolinium‐diethylenetriaminepentaacetic acid were derived from the reference AIF values and averaged to obtain a cohort‐averaged AIF. Influx rate constants (Ki) and proton distribution volumes at zero time (Vp + Vo) were estimated with Patlak plots of AIF‐I, hypothetical AIFs, and cohort‐averaged AIFs and tissue ΔR 1 data. For the regions of interest, the Kis estimated with AIF‐I were slightly but not significantly higher than those obtained with hypothetical AIFs and cohort‐averaged AIF. In contrast, Vp + Vo was significantly higher when calculated with AIF‐I. Similar estimates of Ki and Vp + Vo were obtained with hypothetical AIFs and cohort‐averaged AIF. In summary, AIF‐I underestimated the reference AIF; this shortcoming had little effect on the Ki calculated by Patlak plot but produced a significant overestimation of Vp + Vo. Magn Reson Med 63:1502–1509, 2010.Keywords
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