SPECT, PET and MRI are all key tools to the work-up of patients with neurodegenerative movement disorders. MRI especially has seen increased interest among
researchers. “MRI can contribute to improving diagnostic accuracy and monitoring how a disease is progressing,” said Tarek Yousry, professor of neuroradiology at the Institute of Neuroradiology, University College London. “MRI also has a pivotal role in the planning of functional neurosurgery. You can't do this kind of treatment without imaging,” he added.
MR approaches include morphometric or structural imaging; diffusion-weighted and diffusion tensor imaging (DTI); metabolic imaging, with MR spectroscopy for instance (MRS); and relaxometry, the measurement of relaxation times in the brain.
Two approaches can be taken to structural imaging, according to Professor Stéphane Lehéricy, head of the Centre for NeuroImaging Research (CENIR), part of the Pitié-Salpêtrière Hospital in Paris. Either one can select a particular structure and outline its contours on several slices, allowing the volume of structures such as the striatum or mesencephalum to be monitored. Or automated whole brain techniques, such as voxel-based morphometry, can be performed to compare the amount of grey or white matter in cerebrospinal fluid. Both techniques enable the distinction of Parkinson's disease from other conditions with similar outward symptoms, such as progressive supranuclear palsy and multisystem atrophy.
Diffusion imaging provides a biomarker, the apparent diffusion coefficient, that may improve differential diagnosis; and DTI provides another variable, the anisotropy. “DTI is very interesting because you can obtain a second variable, which is the orientation of diffusion, and use that anisotropy to do fibre tracking,” Prof. Lehéricy explained. DTI thus enables the assessment of pathology within specific fibre tracts. As for MRS, it may be used to acquire more biomarkers that
could help consolidate a diagnosis. But these techniques are still being tested, and it will take a while before they are actually used in clinical practise.
MRI in surgical treatment
MRI currently provides more accuracy in stereotactic surgical treatment for patients with Parkinson's disease and related movement disorders. Implantation of electrodes deep within the brain can help relieve symptoms, but they must be placed very precisely; a necessity MRI can help with. “MRI is central to functional neurosurgery for this patient group,” Prof. Yousry said. “But radiologists who use MRI in this way will need to have the proper anatomical knowledge.”
The European Congress of Radiology (ECR) is the annual meeting of the European Society of Radiology (ESR), the fastest growing medical society in the world, currently with 44,500 members. ECR annually attracts 18,000 delegates from ca. 100 countries to Vienna; the accompanying technical exhibition hosts 285 exhibitors across 26,000 m².