Objective: To determine the inter-rater reliability of Nigrosome-1 detection and its relation to asymmetry of clinical symptoms in Parkinson’s disease (PD). 

Background: Detection of Nigrosome-1 has recently emerged as a surrogate neuroimaging biomarker for evaluation of PD. Studies using 7T and 3T-MRI have reported poor visualization of Nigrosome-1 to be a fairly consistent neuroimaging feature in patients with PD with high diagnostic accuracy, sensitivity and specificity. There is only limited data available on the inter-rater reliability and relationship between poor visualization of Nigrosome-1 and clinical asymmetry in PD.

Methods: 3T High resolution Venobold sequences of 67 patients with PD and 63 matched controls were reviewed by two radiologists blinded to the clinical details of subjects. All subjects were classified into abnormal and normal groups based on visualization of Nigrosome-1. Subjects with abnormal Nigrosome-1 were reclassified based on whether the abnormality was symmetrical or asymmetrical in either side of mesencephalon. Inter-rater reliability was calculated using Cohen’s kappa at each level of classification. Relationship between poor visualization of Nigrosome-1 and clinical asymmetry was also assessed. 

Results: There was good inter-rater reliability of Nigrosome-1 visualization among the reviewers at each level of classification (k=0.75 – 0.92).  Poorly visualized abnormal Nigrosome-1 and clinical asymmetry were contralaterally related in 73.9 % of subjects (p=0.003). Patients with bilaterally symmetrical Nigrosome-1 abnormality were also found to have clinical asymmetry in 50 % patients.

Conclusions: There was good inter-rater reliability of abnormal Nigrosome-1 detection by the reviewers.  There was also significant agreement on clinical asymmetry and poor visualization of Nigrosome-1. However, caution should be exercised while interpreting visualization of Nigrosome1. Further studies are needed.to explore the potential of Nigrosome-1 detection as a surrogate neuroimaging biomarker in PD. 

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MDS Abstracts - https://www.mdsabstracts.org/abstract/clinical-utility-of-visualization-of-nigrosome-1-in-patients-with-parkinsons-disease/