Reliability of Contrast-Enhanced Ultrasound for the Assessment of Muscle Perfusion in Health and Peripheral Arterial Disease

Abstract

We investigated the reliability of contrast-enhanced ultrasound (CEUS) in assessing calf muscle microvascular perfusion in health and disease. Response to a post-occlusive reactive hyperaemia test was repeated on two occasions >48h apart in healthy young (28±7y) and elderly controls (70±5y), and in peripheral arterial disease patients (PAD, 69±7y; n=10, 9 and 8 respectively). Overall, within-individual reliability was poor (coefficient of variation [CV] range: 15-87%); the most reliable parameter was time to peak (TTP, 15-48% CV). Nevertheless, TTP was twice as long in elderly controls and PAD compared to young (19.3±10.4 and 22.0±8.6 vs. 8.9±6.2s respectively; p<0.01), and area under the curve for contrast intensity post-occlusion (a reflection of blood volume) was ~50% lower in elderly controls (.p<0.01 versus PAD and young). Thus, CEUS assessment of muscle perfusion during reactive hyperaemia demonstrated poor reliability, yet still distinguished differences between PAD patients, elderly and young controls.