Blood oxygenation level-dependent MRI in critical limb-threatening ischemia: association with clinical and angiographic findings and response to revascularization.

To investigate the utility of blood oxygenation level-dependent (BOLD) MRI to reflect oxygenation dynamics related to microvascular function in critical limb-threatening ischemia (CLTI), and to examine its associations with clinical and angiographic findings as well as its short-term responsiveness to revascularization. Twenty-seven CLTI patients scheduled for percutaneous transluminal angioplasty (PTA) and 15 age-matched healthy controls underwent calf BOLD MRI with a standardized ischemia–hyperemia paradigm. CLTI patients also underwent BOLD MRI after PTA. Curve parameters, including ischemic minimum value (IMV), time to peak (TTP), gradient during reactive hyperemia (Grad), and peak hyperemic value (HPV), were analyzed. The Bollinger score and collateral number were determined from pre-PTA digital subtraction angiography. Statistical analyses assessed parameter differences between CLTI patients and controls, as well as between pre- and post-PTA, and correlations with the ankle-brachial index (ABI), Rutherford classification, and angiographic findings. Compared with controls, CLTI patients demonstrated less negative IMV (P ≤ 0.04), prolonged TTP (P < 0.001), and reduced Grad (P ≤ 0.008) in all muscle groups. Following PTA, IMV improved, TTP shortened, and Grad increased in CLTI patients (all P < 0.05). TTP correlated negatively with ABI both before and after PTA (R=-0.58, P = 0.002 and R=-0.69, P < 0.001, respectively), and Grad and HPV were positively associated with collateral number (R = 0.41, P = 0.03 and R = 0.54, P = 0.004, respectively). No significant associations were found between BOLD MRI parameters and Rutherford classification or Bollinger scores. BOLD MRI can noninvasively reflect oxygenation dynamics related to microvascular function in CLTI, reveal short-term hemodynamic responses following revascularization, and provide insights into collateral circulation.