Investigation of the significance of quantitative MRI parameters in differentiating PSP from MSA patients

To investigate the utility of quantitative MRI parkinsonism indices in discriminating between progressive supranuclear palsy (PSP) and multiple system atrophy (MSA) patients.

In our study including PSP and MSA patients, we calculated the radiological measures including superior cerebellar peduncle width, middle cerebellar peduncle width, third ventricle width, 3rdV/bifrontal width, pons/mesencephalon (P/M) ratio, P/M ratio 2.0, magnetic resonance parkinsonism index (MRPI), and MRPI 2.0 values. We also constituted a PMS scale to increase the discrimination power.

Comparisons between PSP and MSA patients revealed significant differences in the mesencephalon area, third ventricle width, 3rdV/bifrontal width, P/M ratio, P/M ratio 2.0, MRPI, and MRPI 2.0 values (p < 0.01 for all). The AUC values were acceptable for the third ventricle width, the 3rdV/bifrontal width ratio, the P/M ratio, the P/M 2 ratio, the MRPI and the MRPI-2. In distinguishing PSP, 0 points on the PMS scale had a negative predictive value (NPV) of 91%, whereas 3 points had a positive predictive value (PPV) of 85.7%.

None of the MRI parameters reached a good diagnostic AUC in distinguishing PSP from MSA. However, the PMS scale we propose in this study may provide high PPVs and NPVs for differential diagnosis during desk-based evaluation.