Quantitative assessment of foot microcirculation by CT perfusion differentiates chronic limb-threatening ischemia from claudication in peripheral artery disease

Introduction: Computed tomography perfusion (CTP) is validated to assess foot microcirculatory perfusion in peripheral artery disease (PAD). This study aimed to investigate differences in foot microcirculation on CTP between patients with claudication (Cla) and chronic limb-threatening ischemia (CLTI) and to develop diagnostic models for CLTI. Methods: This single-center prospective study enrolled hospitalized patients with PAD at Huadong Hospital, China (October 2022 to January 2024). Participants underwent preoperative foot CTP and were stratified into Cla (Rutherford category 3) and CLTI (Rutherford categories 4–6) groups. Baseline characteristics and perfusion parameters were recorded. Multivariable logistic regression and receiver operating characteristic curve analysis were performed. Results: A total of 57 patients with PAD were included (34 Cla, 23 CLTI). Resting ankle–brachial index and Global Limb Anatomic Staging System scores did not differ significantly between groups. Diabetes mellitus (DM) prevalence was higher in the CLTI group (95.7% vs 52.9%; p = 0.002). Multivariable logistic regression identified hemoglobin (Hb) level (OR, 0.91; 95% CI, 0.822–0.986; p = 0.024), time to peak (TTP) (OR, 1.135; 95% CI, 1.045–1.250; p = 0.003), and blood flow (BF) (OR, 0.668; 95% CI, 0.499–0.894; p = 0.007) as independent predictors for CLTI. Four diagnostic models were constructed: model A (BF + DM, area under the curve [AUC] 0.864), model B (BF + Hb, AUC 0.890), model C (TTP + DM, AUC 0.895), and model D (TTP + Hb, AUC 0.874). Conclusion: Foot microcirculation differed significantly between patients with Cla and CLTI on CTP. Hb, TTP, and BF were independent predictors for CLTI. All models demonstrated good diagnostic performance, with model C yielding the highest AUC. ClinicalTrials.gov Identifier: NCT05575778.