Objective: To evaluate the accuracy of T2* weighted high resolution 3T Magnetic Resonance Imaging (MRI) in the diagnosis of Parkinson’s disease (PD) in a prospective multicentre case control study.

Background: Establishing the correct diagnosis in the early stages of PD can be difficult even for experienced clinicians. New and easy applicable biomarkers are needed. We recently described a promising 3T MRI biomarker based on demonstration of nigrosome-1 (N1) in the substantia nigra pars compacta (SNpc). We used high resolution T2* MRI to demonstrate iron related signal alterations. The presence of N1 in healthy controls resulted in a ‘swallow tail appearance’ of the SNpc, whereas absence of N1 in PD resulted in a loss of this MRI feature.

Methods: We are conducting a prospective MRI study in patients with PD (co-recruited from the ‘Tracking Parkinson’s study’) and matched controls, collecting imaging data across five UK study sites with varying 3T MRI platforms (PaMIR study). A preliminary analysis of the first 125 subjects (83 PD and 42 age-matched controls) was performed. A blinded neuroradiologist visually assessed the SNpc on high resolution T2* MRI for presence and absence of N1 using a 6 point rating scale (score 1-3, normal; score 4-6, abnormal). Subjects were classified as PD if a unilateral or bilateral abnormal N1 score was demonstrated. Quality of scans was assessed using a quality rating (QR) scale from 1-5 (QR=1, very good; QR=5, non-diagnostic).

Results: MRI scans of 4 subjects (all PD) had to be excluded due to poor quality related to movement artefacts (QR=5). 78 of 79 PD and 40 of 42 control subjects were correctly classified, resulting in an accuracy of 98 % (Sensitivity: 99%, Specificity: 95%). The quality rating for scans in the control population was significantly better (mean QR=2.2±0.9) than in the PD group (mean QR=2.7±0.9, p<0.05, t-Test).

Conclusions: High resolution MRI affords reliable assessment of N1 even in the setting of a multi-centre study with participants scanned on different 3T MRI platforms from 3 different vendors, distinguishing PD subjects from controls with excellent accuracy, sensitivity and specificity. In summary, this study confirms highly characteristic appearances of nigrosome 1 in PD on high resolution T2* MRI scans across several 3T scanner platforms, facilitating its clinical use as diagnostic marker of PD.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/magnetic-resonance-imaging-of-nigrosome-1-in-the-diagnosis-of-early-parkinsons-initial-results-of-the-parkinsons-magnetic-imaging-repository-pamir/