Contrast-enhanced magnetic resonance imaging-based measures of arterial signal-enhancement in patients with peripheral artery disease

Peripheral artery disease (PAD), a form of atherosclerosis of the lower extremities (LE), affects both large vessels and the microcirculation. PAD is associated with intermittent claudication (IC) pain, reduced mobility, and an increased risk of adverse cardiovascular events. Contrast-enhanced magnetic resonance imaging (CE-MRI) of 56 participants (36 PAD patients with IC and 20 matched controls) were acquired at the mid-calf position to quantitatively assess first-pass perfusion in major LE arteries. Arterial signal intensity curves (ASIC) were derived for the anterior tibialis, posterior tibialis, and the peroneal (PE) arteries, representing the respective arterial signal dynamics including local pre-contrast arrival times and peak signal intensities. Several measures were derived from the individual and envelope arterial (composite) measures, each representing signal enhancement (SE), time to peak enhancement (TP), slope of the signal enhancement, and the area under the curve (AUC). Our experimental findings show that higher SE, TP, and AUC were observed in matched controls compared with PAD patients during arterial signal enhancement, suggesting impaired arterial circulation in claudicants. Several arterial measures including TP, SE, and the AUC differed significantly between PAD patients with compared to those without concomitant diabetes, whereas established PAD markers such as the resting and exercise ankle-brachial index (ABI), exercise capacity as measured by treadmill peak walking time and claudication onset time, calf muscle area, and renal function did not. In other analyses involving both legs, PAD patients exhibited significant arterial hemodynamics asymmetry with reduced SE, TP, and AUC in the target leg as compared with the contralateral limb. Among PAD patients with concomitant diabetes, the asymmetry was more pronounced and showed that the maximum and median TP, maximum AUC, sum of AUCs, and envelope AUCs were significantly lower in the target leg compared with the contralateral side. Several of the proposed CE-MRI variables of arterial hemodynamics were significantly associated with key clinical markers of PAD. CE-MRI-derived measures of arterial hemodynamics differentiate PAD patients from matched controls and also identify claudicants with concomitant diabetes who are known to present with an elevated risk for adverse cardiovascular outcomes. The proposed imaging measures could be of interest in the study of PAD status and severity.