235 - Utility of Arterial Spin Labelling and Intravoxel Incoherent Motion MR Pedal Perfusion in Diabetic Foot Ulcer

Purpose: In diabetic patients with extensive infrapopliteal arterial calcifications, conventional vascular assessment tools such as Ankle Brachial Pressure Index and CT angiography are often unreliable. This study compares two non-contrast MRI techniques - Arterial Spin labeling (ASL) and Intravoxel Incoherent Motion (IVIM) - as objective measures of pedal perfusion in diabetic patients with ischemic and neuro-ischemic non-healing foot ulcers.

Materials and Methods: A prospective single-centre cohort study was conducted in twenty two patients with infra-popliteal disease and non-healing foot ulcers. Each patient underwent both ASL and IVIM MRI sequences covering bilateral feet before and after endovascular revascularization. Perfusion metrics from symptomatic and asymptomatic feet were compared to those from healthy controls. ASL measures mean pedal blood flow (mPBF in mL/100g/min), while IVIM-derive perfusion fraction (f) and pseudo-diffusion coefficient (D*) were used as surrogate perfusion markers. Agreement between ASL and IVIM was assessed, and Cox regression analysis was performed to identify predictors of early wound healing.

Results: The mean pre-intervention mPBF in symptomatic feet was 10.58mL/100g/min while increased to a mPBF 15.3mL/100g/min following infrapopliteal angioplasty. The mPBF in healthy controls was 13.45/100g/min. ASL showed high reproducibility across medial forefoot, lateral forefoot and hindfoot locations. IVIM shows a mean pre-intervention perfusion fraction (f) of 0.12 and mean D* value of 1.45 x 10-3mm2/s which showed moderate correlation with pre-intervention ASL values. Multivariate analysis showed regional ASL mPBF (1.008 (1.001 to 1.0015)) and clinical WIFI stage (3.119(1.448-6.719)) as independent predictors of early wound healing.

Conclusion: ASL and IVIM MRI techniques are effective in quantifying pedal perfusion in diabetic patients with ischemic foot ulcers. ASL provides direct and reproducible blood flow measurements, while IVIM offers complimentary microvascular perfusion insights. Perfusion improvements detected by either modality following infrapopliteal angioplasty are predictive of early wound healing, with ASL showing stronger correlation with clinical outcomes.