Abstract 560: Can Time Resolved Peripheral Magnetic Resonance Angiography Predict Functional Lower Limb Impairment in Peripheral Arterial Disease?
Objective: Peripheral arterial disease (PAD) severity, as assessed by ankle brachial index (ABI), significantly correlates with the degree of functional limb impairment. Correlation between severity of PAD, as determined by time resolved magnetic resonance angiography (TR-MRA), and functional limb impairment has not been determined. The aim of this study is to determine if atherosclerotic lesion severity, determined by TR-MRA, can predict the degree of lower limb functional impairment in patients with PAD.
Methods: A total of 258 patients with PAD were prospectively recruited over one year. Demographics, cardiovascular risk factors, clinical lower limb symptoms and a number of functional parameters, including ABI, six-minute walking test, four meter walking velocity (usual + fast speed), Short Form 12 (SF-12) physical functioning score, Walking Impairment Questionnaire (WIQ) distance, speed, and stair climbing score were recorded. TR-MRA was performed using an echo sharing TWIST sequence on a 1.5T Siemens Espree MRI scanner. A single dose of Magnevist (gadopentetate dimeglumine, Berlex, NJ) was administered intravenously. Angiography images from one station, the groin to the knee, were acquired. Lesions were classified according to TASC II Classification, collateral vessels were counted and graded, arterio-venous transit time (AVTT) was calculated.
Results: Time resolved TWIST MRA was performed on 516 lower limbs, 12% (n=62) with TASC D lesions, 29% (n=148) with grade 3– 4 collaterals, mean AVTT of 50.7 seconds. When the study population was divided based on TASC lesion severity (TASC 0, A versus TASC B, C, D), there is a significant difference in ABI (p<0.0001), WIQ distance score (p=0.0135) and WIQ speed score (p=0.0163). When the patients were divided based on collateral grade (grade 0,1,2 versus grade 3,4) there is a significant difference in ABI (p<0.0001), with a trend for WIQ climbing score (p<0.0707).
Conclusion: Time resolved peripheral MRA lesion severity and collateral grade significantly correlates with lower limb functional impairment in patients with PAD. This non-invasive imaging technique can now potentially be reliably employed for PAD severity stratification.