T2*-weighted MRI in diagnosis of multiple system atrophy -: A practical approach for clinicians

Background Putaminal iron deposition is a histopathological feature of multiple system atrophy (MSA), which is not observed in patients with idiopathic Parkinson's disease (PD). T2*-weighted magnetic resonance imaging (MRI) gradient echo (GE) sequences are sensitive for paramagnetic susceptibility changes and therefore may support the clinical differential diagnosis between MSA and PD. Methods We evaluated putaminal signal intensities on 1.0 Tesla scans of 52 MSA patients, 88 patients with PD and 29 healthy control subjects. Results The typical finding in T2* GE sequences of MSA patients was a signal loss of the dorsolateral putamen, which showed a high specificity (>0.91), but was present in only a subpopulation of patients (sensitivity 0.64-0.69). The combination of the latter with additional presence of a hyperintense lateral rim in fluid attenuated inversion recovery (FLAIR) sequences increased the specificity to 0.97. Using a quantitative evaluation of putaminal signal intensities in defined regions of interest MSA and PD could be discriminated with a diagnostic accuracy (r) of up to 0.82. Conclusion Although the separation of groups remains incomplete, the use of T2*-weighted GE sequences combined with FLAIR may be helpful for the differential diagnosis of MSA versus PD considering its fast application, easy evaluation, broad availability, the specificity of findings and the presence of putaminal signal loss already at early disease stages.