I-MIBG myocardial scintigraphy for the evaluation of Lewy body disease: are delayed images essential? Is visual assessment useful?

Objective:: We performed I-meta-iodobenzylguanidine (I-MIBG) myocardial scintigraphy for the diagnosis of Lewy body disease (LBD) and assessed whether the early heart-to-mediastinum (H/M) ratio was diagnostic and whether visual image analysis was useful.

Methods:: Our study included 453 patients with clinically suspected LBD who had undergone I-MIBG myocardial scintigraphy. We evaluated semi-quantitative values (early and delayed H/M ratio, washout rate) and performed visual image analysis. The sensitivity, specificity, accuracy, positive-predictive value (PPV) and negative-predictive value (NPV) of both analyses were calculated.

Results:: The early H/M ratio exhibited the best diagnostic ability. Its overall sensitivity, specificity, accuracy, PPV and NPV were 72.2%, 93.1%, 84.3%, 88.5% and 82.2%, respectively (cut-off value 2.2 or less). However, there was no significant difference from the delayed H/M ratio or the results of visual assessment.

Conclusion:: I-MIBG myocardial scintigraphy accurately differentiates between patients with and without LBD and a correct diagnosis can be established based on the early H/M ratio. We also document that visual evaluation of scintigrams is useful. Therefore, patients may benefit from the single performance of the procedure because a correct diagnosis can be obtained early in the disease process and their prognosis and appropriate treatment can be determined.

Advances In Knowledge:: I-MIBG myocardial scintigraphy on the early H/M ratio makes it possible to differentiate between patients with LBD and patients without LBD.