Interobserver Agreement in the Diagnosis of Parkinson Disease with Cardiac¹²³I-Metaiodobenzylguanidine Scintigraphy

Abstract

The aim of this study was to analyze the interobserver agreement of visual and quantitative assessment of cardiac 123 I-metaiodobenzylguanidine scintigraphy. Methods: Planar images were acquired using a low-energy collimator. The heart-to-mediastinum (HM) ratio was adjusted for the use of a low-energy collimator, using a published formula. Interpretation was undertaken both visually and after the addition of adjusted HM ratios. Image findings 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 (k 5 0.82, P , 0.01). Adjusted HM ratios led to a significant increase in mean ratios (1.79 vs. 1.36, P 5 0.02) and, when utilized in reporting, resulted in perfect agreement (k 5 1.0, P , 0.01). Conclusion: The use of quantified HM ratios adjusted for low-energy collimator use improves on visual assessment alone and allowed for excellent interobserver agreement.