Simple quantitative planimetric measurement of nigrosome-1 for clinical settings

Minh T Chau; Marc Agzarian; Robert A Wilcox; Andrew Dwyer; Eva Bezak; Gabrielle Todd

doi:10.1016/j.jns.2023.120857

Simple quantitative planimetric measurement of nigrosome-1 for clinical settings

J Neurol Sci. 2023 Nov 15:454:120857. doi: 10.1016/j.jns.2023.120857. Epub 2023 Oct 29.

Authors

Minh T Chau¹, Marc Agzarian², Robert A Wilcox³, Andrew Dwyer⁴, Eva Bezak⁵, Gabrielle Todd⁶

Affiliations

¹ UniSA Allied Health & Human Performance and Alliance for Research in Exercise, Nutrition and Activity (ARENA), City East Campus, University of South Australia, GPO Box 2471, Adelaide, SA 5001, Australia; South Australia Medical Imaging, Flinders Medical Centre, 1 Flinders Drive, Bedford Park, SA 5042, Australia.
² South Australia Medical Imaging, Flinders Medical Centre, 1 Flinders Drive, Bedford Park, SA 5042, Australia; College of Medicine and Public Health, Flinders University, 1 Flinders Drive, Bedford Park, SA 5042, Australia.
³ College of Medicine and Public Health, Flinders University, 1 Flinders Drive, Bedford Park, SA 5042, Australia; Neurology Department, Flinders Medical Centre, 1 Flinders Drive, Bedford Park, SA 5042, Australia; UniSA Clinical & Health Sciences and Alliance for Research in Exercise, Nutrition and Activity (ARENA), City East Campus, University of South Australia, GPO Box 2471, Adelaide, SA 5001, Australia.
⁴ South Australia Medical Imaging, Flinders Medical Centre, 1 Flinders Drive, Bedford Park, SA 5042, Australia; College of Medicine and Public Health, Flinders University, 1 Flinders Drive, Bedford Park, SA 5042, Australia; Clinical and Research Imaging Centre, South Australian Health and Medical Research Institute, PO Box 11060, Adelaide, SA 5000, Australia.
⁵ UniSA Allied Health & Human Performance and Alliance for Research in Exercise, Nutrition and Activity (ARENA), City East Campus, University of South Australia, GPO Box 2471, Adelaide, SA 5001, Australia.
⁶ UniSA Clinical & Health Sciences and Alliance for Research in Exercise, Nutrition and Activity (ARENA), City East Campus, University of South Australia, GPO Box 2471, Adelaide, SA 5001, Australia. Electronic address: gabrielle.todd@unisa.edu.au.

PMID: 37939625
DOI: 10.1016/j.jns.2023.120857

Abstract

Introduction: Loss of MRI hyperintense signal in nigrosome-1 (assessed with susceptibility-weighted imaging) is a biomarker for Parkinson's disease (PD). Current clinical practice involves subjectively rating the appearance of nigrosome-1 which is challenging. The study aimed to test and compare a simple method for quantifying nigrosome-1 with the current subjective rating method.

Methods: Two experienced neuroradiologists measured area of hyperintense signal in nigrosome-1 (quantitative method) and rated nigrosome-1 appearance (as normal, attenuated, or absent; subjective method) in 42 patients encompassing the full spectrum of nigrosome-1 integrity (21 patients aged 55.5 ± 20.9 years with Essential tremor (ET) and a subset of 21 patients aged 69.6 ± 8.6 years with PD). Neuroradiologists were blinded to each other's measurements, clinical notes, and patient group.

Results: Both methods yielded a significant difference between the groups (PD vs ET; p < 0.001). Pooled (across sides) area of nigrosome-1 hyperintense signal was significantly smaller in the PD group (median = 2.1 mm², range = 0-15.8 mm²) than ET group (median = 8.3 mm², range = 0-15.7 mm²; p < 0.001). Inter-rater reliability was high to very high for both methods (subjective: weighted kappa = 0.640, p < 0.001; quantitative: W = 0.733, p = 0.004). Our primary hypothesis that area of nigrosome-1 hyperintense signal exhibits higher inter-rater reliability than subjective rating of nigrosome-1 appearance was not supported.

Conclusion: The simple quantitative method, used with subjectively rated nigrosome-1 appearance, may improve confidence in longitudinal clinical reporting, when nigrosome-1 is attenuated. However, further work on the incremental diagnostic value of planimetry and bias, repeatability and reproducibility are needed before it can be recommended in clinical practice.

Keywords: Magnetic resonance imaging; Nigrosome-1; Parkinson's disease; Substantia nigra.

MeSH terms

Essential Tremor* / diagnostic imaging
Humans
Magnetic Resonance Imaging / methods
Parkinson Disease* / diagnostic imaging
Reproducibility of Results
Substantia Nigra