Albert Stezin1,2, Rajini M Naduthota2, Ragasudha Botta1,2, Shriram Varadharajan3, Abhishek Lenka1,2, Jitender Saini3, Ravi Yadav2, Pramod Kumar Pal4. 1. Department of Clinical Neuroscience, National Institute of Mental Health and Neurosciences, Hosur Road, Bangalore, 560029, Karnataka, India. 2. Department of Neurology, National Institute of Mental Health & Neurosciences (NIMHANS), Hosur Road, Bangalore, 560029, Karnataka, India. 3. Department of Neuroimaging and Interventional Radiology, National Institute of Mental Health and Neurosciences, Hosur Road, Bangalore, 560029, Karnataka, India. 4. Department of Neurology, National Institute of Mental Health & Neurosciences (NIMHANS), Hosur Road, Bangalore, 560029, Karnataka, India. palpramod@hotmail.com.
Abstract
OBJECTIVE: To determine the diagnostic characteristics of poor visualisation of nigrosome-1 as a neuroimaging biomarker in Parkinson's disease (PD) and to explore the relationship of poor visualisation of nigrosome-1 and clinical asymmetry. METHODS: High-resolution gradient-echo sequences of 67 patients with PD and 63 healthy controls were reviewed by two radiologists blinded to the clinical details. A three-tier classification system was used to categorise the scans based on the visualisation of nigrosome-1, and inter-rater reliability was calculated at each level of classification. Other diagnostic properties such as sensitivity, specificity and predictive values were calculated. The relationship between poor visualisation of nigrosome-1 and clinical asymmetry was also assessed. RESULTS: Poor visualisation of nigrosome-1 had high sensitivity (98.5%), specificity (93.6%), positive-predictive value (94.3%), negative-predictive value (98.3%), accuracy (96%) and inter-rater reliability (k = 0.75-0.92). Poorly visualised nigrosome-1 was significantly associated with higher motor asymmetry in the contralateral side in 64.8% of subjects (p = 0.004). CONCLUSIONS: Poor visualisation of nigrosome-1 in PD had good diagnostic properties as a neuroimaging biomarker in PD. There was also a significant agreement on clinical asymmetry and poor visualisation of nigrosome-1. KEY POINTS: • Nigrosome-1 represents the largest collection of dopaminergic neurons in dorso-lateral substantia nigra. • Loss of nigrosome-1 is being studied as a biomarker in Parkinson's disease. • Visualisation of nigrosome-1 had good diagnostic properties as a biomarker. • There was a contralateral relationship between nigrosome-1 lateralisation and clinical asymmetry. • We also highlight the potential limitations of nigrosome-1 visualisation as a biomarker.
OBJECTIVE: To determine the diagnostic characteristics of poor visualisation of nigrosome-1 as a neuroimaging biomarker in Parkinson's disease (PD) and to explore the relationship of poor visualisation of nigrosome-1 and clinical asymmetry. METHODS: High-resolution gradient-echo sequences of 67 patients with PD and 63 healthy controls were reviewed by two radiologists blinded to the clinical details. A three-tier classification system was used to categorise the scans based on the visualisation of nigrosome-1, and inter-rater reliability was calculated at each level of classification. Other diagnostic properties such as sensitivity, specificity and predictive values were calculated. The relationship between poor visualisation of nigrosome-1 and clinical asymmetry was also assessed. RESULTS: Poor visualisation of nigrosome-1 had high sensitivity (98.5%), specificity (93.6%), positive-predictive value (94.3%), negative-predictive value (98.3%), accuracy (96%) and inter-rater reliability (k = 0.75-0.92). Poorly visualised nigrosome-1 was significantly associated with higher motor asymmetry in the contralateral side in 64.8% of subjects (p = 0.004). CONCLUSIONS: Poor visualisation of nigrosome-1 in PD had good diagnostic properties as a neuroimaging biomarker in PD. There was also a significant agreement on clinical asymmetry and poor visualisation of nigrosome-1. KEY POINTS: • Nigrosome-1 represents the largest collection of dopaminergic neurons in dorso-lateral substantia nigra. • Loss of nigrosome-1 is being studied as a biomarker in Parkinson's disease. • Visualisation of nigrosome-1 had good diagnostic properties as a biomarker. • There was a contralateral relationship between nigrosome-1 lateralisation and clinical asymmetry. • We also highlight the potential limitations of nigrosome-1 visualisation as a biomarker.
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