Abstract

Objective: To determine whether apparent diffusion coefficient (ADC) values and fractional anisotropy (FA) values can detect early pathological involvement in multiple system atrophy (MSA), and be used to differentiate MSA-P from Parkinsonfs disease (PD).

Methods: We compared ADC and FA values in the pons, cerebellum and putamen of 61 subjects (20 probable MSA patients, 21 age-matched PD patients, and 20 age-matched healthy controls) using a 3.0T MR system.

Results: ADC values in the pons, cerebellum and putamen were significantly higher, and FA values lower in MSA than in PD or controls. These differences were prominent in MSA lacking dorsolateral putaminal hyperintensity (DPH) or hot cross bun (HCB) sign. In differentiating MSA-P from PD using FA and ADC values, we obtained equal sensitivity (70%) and higher specificity (100%) in the pons than in the putamen and cerebellum. In addition, all patients that had both significant low FA and high ADC values in each of these three areas were MSA-P cases, and those that had both normal FA and ADC values in the pons were all PD cases. Our diagnostic algorithm based on these results accurately diagnosed 90% of patients with MSA-P.

Conclusion: FA and ADC values could detect early pathological involvement prior to MR signal changes in MSA. Particularly, low FA values in the pons showed high specificity in discriminating MSA-P from PD. In addition, combined analysis of both FA and ADC values in all three areas was more useful than only one or the other.