Establishing Magnetic Resonance Parkinsonism Index reference ranges to distinguish Progressive Supranuclear Palsy and Corticobasal Syndrome

Motivation: distinguishing Parkinsonian syndromes can be challenging since these diseases exhibit overlapping clinical manifestation. Goal(s): provide extended reference ranges of established biomarkers to distinguish Progressive Supranuclear Palsy (PSP) from Corticobasal Syndrome (CBS) in a fast, automated way. Approach: we build reference ranges of relevant brain measurements from a large cohort of healthy subjects; then, we compute corresponding Z-scores of these measurements to distinguish PSP and CBS patients. Results: the midbrain area is the most informative measurement to discern PSP and CBS. A logistic regressor that combines Z-scores of multiple brain measurements achieves mean AUC of .87 in 5-fold-cross-validation when distinguishing PSP and CBS. Impact: We release extended age-/sex-specific reference ranges built from healthy controls for several biomarkers used to differentiate Parkinsonian disorders. Our ranges show notable variation with age/sex and could be used by radiologists as benchmark to better differentiate Parkinsonian subtypes.