Significance of combined use of MRI and perfusion SPECT for evaluation of multiple system atrophy, cerebellar type

Background Multiple system atrophy, cerebellar type (MSA-C) sometimes shows asymmetrical findings on magnetic resonance imaging (MRI) and single photon emission computed tomography (SPECT). Purpose To assess the frequency and clinical significance of asymmetrical MRI and 99mTc-ethyl cysteinate dimer perfusion (ECD) SPECT findings of the cerebellum, middle cerebellar peduncle (MCP), and pons in MSA-C patients. Material and Methods We retrospectively reviewed 28 patients with MSA-C who underwent MRI and 99mTc-ECD SPECT and evaluated laterality of atrophy and signal changes on MRI, and laterality of perfusion on 99mTc-ECD SPECT transversely and longitudinally. Results Laterality was identified for 64%, 61%, and 21% of atrophy in the cerebellum, MCP, and pons, respectively, on MRI and for 71% of atrophy in the cerebellum on perfusion SPECT. Concerning comparisons between the latest MRI and SPECT findings, laterality of cerebellar/MCP atrophy on MRI and decreased cerebellar perfusion on SPECT was matched in 57%, mismatched in 11%, and absent in 25% of patients. On past images, MRI and SPECT showed matched laterality in 33%, mismatched laterality in 27%, no laterality in 13%, and SPECT precedent laterality in 27% of patients. Including the latest and past images, asymmetrical changes were observed in 75% of patients. We could not identify any correlation between laterality of image findings and cerebellar symptoms in most patients. Conclusion Asymmetrical changes on MRI and perfusion SPECT are common in MSA-C patients. Perfusion SPECT is useful for diagnosing MSA-C in the early stages from a functional perspective.