Interobserver Agreement In The Diagnosis Of Parkinson’s Disease With Cardiac ¹²³I-meta-iodobenzylguanidine Scintigraphy

Abstract

Rationale: The aim of this study was to analyse the interobserver agreement of visual and quantitative assessment of cardiac ¹²³I-MIBG scintigraphy. Methods: Planar images were acquired using a low-energy collimator. The heart-to-mediastinal ratio (HM ratio) was adjusted for the use of a low-energy collimator, using a published formula. Interpretation was undertaken on both visual interpretation and following the addition of adjusted HM ratios. Images were classified as normal, abnormal or borderline. Results: The cohort consisted of 10 patients. On visual interpretation only, there was strong agreement on the interpretation of the scan, κ = .82, p<0.01. Adjusted HM ratios led to a significant increase in mean ratios, (1.79 vs 1.36, P = 0.02) and when utilised in reporting, resulted in perfect agreement, κ = 1.0, p<0.01. Conclusion: The use of quantified HM ratios, adjusted for low-energy collimator use improves upon visual assessment alone and allowed for excellent interobserver agreement.