Putaminal T1/T2-weighted ratio is increased in PSP compared to PD and healthy controls, a multi-cohort study

Introduction: Differentiating Parkinson's disease (PD) from progressive supranuclear palsy (PSP) and multiple system atrophy (MSA) is a common clinical problem. We aimed to apply the T₁-/T₂-weighted ratio imaging technique, based on standard clinical MRI, to reveal differences in neurodegeneration in three large cohorts. Methods: Three cohorts, with a total of 405 participants (269 PD, 44 PSP, 38 MSA, 54 controls), were combined and T₁/T₂-weighted ratio image analyses were carried out. A combination of automatic segmentation and atlas-based ROI were used in this study. The cohorts were combined using the ComBat batch correction procedure. Results: Group differences were found in the putamen (p = 0.040), with higher T₁/T₂-weighted ratio in this region in PSP compared to PD and healthy controls (p-values 0.010 and 0.007 respectively). Using putaminal T₁/T₂-weighted ratio for diagnostic separation, a fair performance was found in separating PSP from healthy controls, with an area under the receiver operating characteristic curve of 0.701. Conclusion: Different patterns of T₁/T₂-weighted ratio, reflecting differences in underlying pathophysiology, were found between the groups. Since T₁/T₂-weighted ratio can be applied to standard clinical MRI sequences to allow more quantitative analyses, this seems to be a promising biomarker for diagnostics and treatment evaluation of parkinsonian disorders for clinical trials.