Whole-Body Thallium Imaging in Coronary Artery Disease

The aim of this study was to evaluate the incidence, type, and severity of asymptomatic leg perfusion abnormalities in 116 male patients with proven coronary artery disease (CAD) who performed near-maximal treadmill test. Interextremity asymmetry was observed in 60% of patients, but the incidence of this sign increased with age (from 35% below forty-five years of age to 72% over sixty-one years). Asymmetry was very marked or marked in 61% of all segments and moderate in 39% of them. A significant decrease in fractional uptake was observed in 21% of patients with CAD and in 25% of those with interextremity asymmetry. Myocardial ischemia, which was defined by reversible defects on myocardial tomoscintigraphy, was three times more frequent in patients with interextremity asymmetry than in patients with normal results from exercise whole-body thallium scintigraphy. This observation, combined with type, extent, and location of asymmetry, is highly suggestive of silent peripheral arterial disease in most cases. Whole-body scan could easily be performed following an exercise myocardial thallium scan so as to provide information on multifocal atherosclerosis in patients with CAD or multiple and severe vascular risk factors. The prognostic value of these silent peripheral muscle perfusion abnormalities remains to be established.