Assessment of brain iron and neuronal integrity in patients with Parkinson's disease using novel MRI contrasts
- 5 December 2006
- journal article
- research article
- Published by Wiley in Movement Disorders
- Vol. 22 (3), 334-340
- https://doi.org/10.1002/mds.21227
Abstract
Postmortem demonstration of increased iron in the substantia nigra (SN) is a well‐appreciated finding in Parkinson's disease (PD). Iron facilitates generation of free radicals, which are thought to play a role in dopamine neuronal loss. To date, however, magnetic resonance imaging (MRI) has failed to show significant in vivo differences in SN iron levels in subjects with PD versus control subjects. This finding may be due to the limitations in tissue contrasts achievable with conventional T1‐ and T2‐weighted MRI sequences that have been used. With the recent development of novel rotating frame transverse (T2ρ) and longitudinal (T1ρ) relaxation MRI methods that appear to be sensitive to iron and neuronal loss, respectively, we embarked on a study of 8 individuals with PD (Hoehn & Yahr, Stage II) and 8 age‐matched control subjects. Using these techniques with a 4T MRI magnet, we assessed iron deposits and neuronal integrity in the SN. First, T2ρ MRI, which is reflective of iron‐related dynamic dephasing mechanisms (e.g., chemical exchange and diffusion in the locally different magnetic susceptibilities), demonstrated a statistically significant difference between the PD and control group, while routine T2 MRI did not. Second, T1ρ measurements, which appear to reflect upon neuronal count, indicated neuronal loss in the SN in PD. We show here that sub‐millimeter resolution T1ρ and T2ρ MRI relaxation methods can provide a noninvasive measure of iron content as well as evidence of neuronal loss in the midbrain of patients with PD. © 2006 Movement Disorder SocietyKeywords
This publication has 37 references indexed in Scilit:
- Transcranial sonography and [123I]FP-CIT SPECT disclose complementary aspects of Parkinson's diseaseBrain, 2006
- Substantia nigra hyperechogenicity as a marker of predisposition and slower progression in Parkinson's diseaseMovement Disorders, 2005
- T2ρ‐weighted contrast in MR images of the human brainMagnetic Resonance in Medicine, 2004
- Reduction of residual dipolar interaction in cartilage by spin‐lock techniqueMagnetic Resonance in Medicine, 2004
- Neuroprotection and pharmacotherapy for motor symptoms in Parkinson's diseaseThe Lancet Neurology, 2004
- On‐ and off‐resonance T1ρ MRI in acute cerebral ischemia of the ratMagnetic Resonance in Medicine, 2002
- In vivo 1H2O T measurement in the human occipital lobe at 4T and 7T by Carr‐Purcell MRI: Detection of microscopic susceptibility contrastMagnetic Resonance in Medicine, 2002
- The substantia nigra of the human brainBrain, 1999
- High frequency volume coils for clinical NMR imaging and spectroscopyMagnetic Resonance in Medicine, 1994
- Highly selective π2 and π pulse generationJournal of Magnetic Resonance (1969), 1984