Diabetes is an important independent risk factor for peripheral arterial disease (PAD) and patients with both PAD and diabetes are more likely to have wound formation, infection, and higher risk of limb loss. A hallmark of PAD in the setting of diabetes, is the accumulation of densely calcified, recalcitrant, occlusive disease of the tibial and pedal arteries. However, it is difficult to non-invasively assess patency of tibial and pedal outflow arteries accurately in the lower extremities of the patients with diabetes, due to multi-segment, diffuse, and calcified plaques. In addition, the contrast media used in current clinical diagnostic tools, such as digital subtraction angiography (DSA), computerized tomographic angiography (CTA), or contrast-enhanced magnetic resonance angiography, are contraindicated to patients with diabetes who have renal insufficiency. The contrast free magnetic resonance angiography (CF-MRA) becomes a favorable imaging method in these patients. Current CF-MRA techniques demonstrated good sensitivity and specificity for the detection of arterial stenosis in lower extremities, but relies on the electrocardiography (ECG) triggering. Irregular ECG signals in patients with diabetes who are more likely to be overweight and/or obese results in suboptimal or useless angiographic findings. More importantly, current CF-MRA techniques have no robust methods to assess the extent of arterial wall calcification. The objective of this study is to develop and validate a new CF-MRA technique, without using any ECG signal, to assess both arterial stenosis and calcification.
Two specific aims will be addressed.
In Specific Aim 1, a new CF-MRA technique for quantitative measurements of arterial outflow vessel stenosis and calcification will be developed and validated in a 3D printed calcified vascular phantom.
In Specific Aim 2, sensitivity and specificity of vascular calcification and stenosis detection will be determined in the lower extremities of 25 patients with symptomatic PAD and diabetes using the new CF-MRA technique, in comparison with CTA and DSA, respectively. It is hypothesized that the extent of calcification and stenosis degree measured by the new CF-MRA will be strongly correlated with the actual size of calcification and stenosis in the phantom (r > 0.9). High sensitivity and specificity (> 90%) will be achieved for the detection of calcification and stenosis with the new CF-MRA. The completion of this study will build a foundation to comprehensively assess the vasculature in the lower extremities of patients with PAD and diabetes, which is essential to effective treatment plans for revascularization and limb salvage.
This project is to develop and evaluate a new contrast free magnetic resonance angiography technique for the diagnosis of arterial stenosis and calcification in lower extremities of patients with both peripheral arterial disease and diabetes. We will develop and validate this new angiography method in 3D-printed calcified vessel phantoms and this cohort of patients, in comparison with clinical reference methods. The technical advancement will be essential to develop effective treatment plans for revascularization and limb salvage.
