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Dr. Okun

Post of the Week: MRI's have improved to examine dopamine system

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Dear forum members,


Interesting developments in imaging over the last 24 months. MRI scanners which typically for humans have been performed with 1.5-3.5 Tesla units---have now been tested with 7 Tesla units. The pictures are amazing and they have revealed beautiful images of the dopamine system and many basal ganglia structures important to PD. The next step is testing in PD patients and making the scans tolerable (the magnets can cause nausea and side effects at that strong power).


Here is a recent article in normal patients-- and another recent one last year (not shown) highlighted the potential importance for better targeting DBS.



AJNR Am J Neuroradiol. 2010 Dec 23. [Epub ahead of print]

Using High-Resolution MR Imaging at 7T to Evaluate the Anatomy of the Midbrain Dopaminergic System.

Eapen M, Zald DH, Gatenby JC, Ding Z, Gore JC.


From Vanderbilt Neuroscience, Vanderbilt Institute of Imaging Science, Department of Radiology and Radiological Sciences, Vanderbilt Department of Psychology, and Department of Biomedical Engineering, Vanderbilt University, Nashville, Tennessee.


BACKGROUND AND PURPOSE: Dysfunction of DA neurotransmission from the SN and VTA has been implicated in neuropsychiatric diseases, including Parkinson disease and schizophrenia. Unfortunately, these midbrain DA structures are difficult to define on clinical MR imaging. To more precisely evaluate the anatomic architecture of the DA midbrain, we scanned healthy participants with a 7T MR imaging system. Here we contrast the performance of high-resolution T2- and T2*-weighted GRASE and FFE MR imaging scans at 7T.


MATERIALS AND METHODS: Ten healthy participants were scanned by using GRASE and FFE sequences. CNRs were calculated among the SN, VTA, and RN, and their volumes were estimated by using a segmentation algorithm.


RESULTS: Both GRASE and FFE scans revealed visible contrast between midbrain DA regions. The GRASE scan showed higher CNRs compared with the FFE scan. The T2* contrast of the FFE scan further delineated substructures and microvasculature within the midbrain SN and RN. Segmentation and volume estimation of the midbrain SN, RN, and VTA showed individual differences in the size and volume of these structures across participants.


CONCLUSIONS: Both GRASE and FFE provide sufficient CNR to evaluate the anatomy of the midbrain DA system. The FFE in particular reveals vascular details and substructure information within the midbrain regions that could be useful for examining structural changes in midbrain pathologies.


PMID: 21183619 [PubMed - as supplied by publisher]


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