Use of Blood Oxygenation Level‐Dependent MRI to Predict Clinical Outcomes After Endovascular Revascularization in Peripheral Artery Disease

ABSTRACT Background Blood oxygenation level‐dependent ( BOLD ) MRI can noninvasively quantify lower extremity perfusion in peripheral artery disease ( PAD ) patients. However, its ability to reflect perfusion change in response to lower extremity revascularization ( LER ) and its prognostic value for clinical outcomes are not fully understood. Purpose To evaluate BOLD MRI response to LER and its predictive value for major adverse cardiovascular events ( MACE ) and major adverse limb events ( MALE ) in PAD patients. Study Type Prospective. Population Forty‐one patients (median age, 73 years; 29 men) undergoing LER for symptomatic PAD. Field Strength/Sequence 3.0 T/BOLD MRI with a multi‐echo gradient‐recalled echo sequence. Assessment Pre‐ and post‐LER BOLD MRI was performed under an ischemia‐hyperemia paradigm. Normalized T2* time course curves were generated in each of 5 calf muscle compartments (anterior, lateral, deep posterior, soleus, and gastrocnemius) and times to peak (TTP), minimum/maximum values, and gradients during hyperemia (Grad) analyzed. Follow‐up was every 6–12 months via hospital records and telephone interviews for MACE and MALE outcomes. Model 1 (clinical factors) and Model 2 (+BOLD MRI) were compared. Statistical Tests Chi‐square test or Fisher's exact test, Student's t‐test or Wilcoxon rank‐sum test, area under the receiver operating characteristic curve (AUC), Kaplan–Meier survival analysis, and Cox proportional hazards regression analysis. Significance was set at p < 0.05. Results During a median 38‐month follow‐up, 9 patients experienced MACE and 20 experienced MALE . Successful LER improved TTP and Grad in all muscle compartments. Grad change ( ΔGrad sol ) and post‐ LER TTP ( TTP sol ) in the soleus muscle achieved the highest AUC values of 0.92 and 0.80 in predicting MACE and MALE , respectively. In multivariable Cox regression analysis, ΔGrad sol and TTP sol were independent predictors of MACE (hazard ratio HR per standard deviation SD increase, 0.23) and MALE ( HR per SD increase, 1.62), respectively. BOLD MRI added incremental prognostic value to clinical factors, increasing C‐index by 0.06 for MACE and 0.05 for MALE . Data Conclusion BOLD MRI showed perfusion changes in skeletal muscles following revascularization and provided incremental prognostic value in PAD patients. Evidence Level 2. Technical Efficacy Stage 4.