Time-resolved MR angiography of the calf arteries using a phased array cardiac coil: comparison of visibility with standard three-step bolus chase MR angiography

Background Standard bolus chase MR angiography (MRA) is increasingly replacing digital subtraction angiography (DSA) in the diagnostic evaluation of peripheral vascular disease. However, a major limitation of bolus chase MRA is the relatively poor visibility of the calf arteries. Purpose To evaluate the feasibility of visualizing the calf arteries and the visibility quality of an 8-channel cardiac phased array coil using time-resolved imaging of contrast kinetics (TRICKS) MRA compared with standard bolus chase MRA on a 1.5 Tesla MRI scanner. Material and Methods MRA findings of 59 sequential patients (mean age 57.8 years, range 14-83 years; 41 men) were retrospectively evaluated. All examinations included preliminary TRICKS for the lower leg using a surface 8-channel cardiac coil, followed by a 3-step MRA of the abdominal aorta, thigh, and lower leg using a body coil. Images yielded by both methods were separately evaluated by consensus of two radiologists unaware of the patients’ clinical data. Visibility of the calf arteries (popliteal, tibialis anterior, tibialis posterior, tibioperoneal trunk, and peroneal) for both sides was subjectively classified as ‘diagnostic’ or ‘non-diagnostic’. Descriptive statistics for image diagnostic quality were assessed. Results A total of 575 calf arterial segments were evaluated. Visibility of all calf arteries was significantly better with TRICKS than with the standard bolus chase MRA ( P < 0.001). The improvement of calf artery visibility with TRICKS was more pronounced in patients with peripheral vascular disease compared to those with arteritis, vascular malformation and popliteal entrapment syndrome. Conclusion Using a cardiac coil for MRA of the lower extremities resulted in visibility comparable to that of a dedicated leg coil, with diagnostic superiority for the TRICKS method compared to the standard bolus chase method.