TRICKS magnetic resonance angiography at 3-tesla for assessing whole lower extremity vascular tree in patients with high-grade critical limb ischemia: DSA and TASC II guidelines correlations

Abstract

The entire vascular tree of 58 lower extremities with high-grade critical limb ischemia (CLI) was assessed with three-station time resolved imaging of contrast kinetics (TRICKS) magnetic resonance angiography (T-MRA) and correlated with digital subtraction angiography (DSA) examinations and Trans-Atlantic Inter-Society Consensus II (TASC II) guidelines. Kappa (κ) statistics were utilized to evaluate the agreement of stenosis scores (5-point scale; 0 normal to 4 occlusion) based on T-MRA and DSA. With DSA as the standard, significant stenosis instances (stenosis score ≥2) among vascular segments were compared. The κ-statistics of image quality (4-point scale; 1 nondiagnostic to 4 excellent) of T-MRA and TASC II classification assessed by a radiologist and a vascular surgeon were also evaluated. Among 870 vascular segments, excellent agreement was observed between T-MRA and DSA (mean κ = 0.883) in revealing stenosis (mean stenosis score, 2.1 ± 1.3 versus 2.0 ± 1.3). T-MRA harbored overall high sensitivity (99.5%), specificity (93.6%), positive predictive value (95.4%), negative predictive value (99.6%), and accuracy (97.7%) in depicting significant stenosis. Excellent interobserver agreement (mean κ = 0.818) of superb image quality (mean score = 3.5-3.6) of T-MRA and outstanding agreement of TASC II classification of aortoiliac and femoral-popliteal lesions (κ = 0.912-0.917) between two raters further verified the clinical feasibility of T-MRA for treatment planning.

Figure 1

A 60-year-old man with unhealed ulcers over the left heel region for 4 months. (a) T-MRA with MIP reconstruction at 36 s after contrast medium injection demonstrating peak arterial enhancement of the right distal run-off station with clear depiction of infrapopliteal and pedal arteries without venous overlay. The left leg vessels are not poorly opacified. (b) T-MRA at 42 s time frame demonstrating peak arterial enhancement of the left leg with multiple significant stenoses (arrows) in the left posterior tibial artery and dorsalis pedis and nonopacification of planter artery. The right leg is obscured due to prominent venous contamination. Without a time-resolved approach, clear depiction of infrapopliteal and pedal vessels would have been difficult due to discrepant arterial inflow.

Figure 2

A 67-year-old male with ischemic rest pain and poor healing of the right foot. (a) Targeted peak arterial time frame of T-MRA of the right distal runoff station in oblique reconstruction demonstrating occlusion of posterior tibial artery and distal third of the anterior tibial and peroneal arteries (arrow). Plantar artery is not visible while dorsalis pedis is patent (open arrow). (b) Corresponding DSA demonstrating similar findings to the infrapopliteal portion. The pedal vessels are not opacified. Subsequent surgery confirmed patency of dorsalis pedis artery as demonstrated on T-MRA.

Figure 3

A 72-year-old male with bilateral lower leg ischemic rest pain and left foot ulcers. (a) Concatenated three-station T-MRA demonstrating multiple stenoses (arrows) (type B lesion based on TASC classification) in the left superficial femoral artery and multiple long segmental severe stenoses and occlusions of the infrapopliteal arteries. The left dorsalis pedis artery (open arrow) is patent. (b) Corresponding concatenated DSA demonstrating multiple stenoses in the left superficial femoral artery. The infrapopliteal and pedal arteries beyond the left knee are not opacified. (c) Follow-up angiogram after angioplasty of the left superficial femoral artery showing residual mild stenoses (arrows). (d) Selective DSA of the left foot after angioplasty with improved arterial inflow confirming the patency of the dorsal pedis artery (open arrow); the patient was subsequently managed with popliteal-dorsalis pedis bypass grafting.