Gray-scale median of the atherosclerotic plaque can predict success of lumen re-entry during subintimal femoral-popliteal angioplasty

Objective This study assessed whether the duplex ultrasound (DUS)–derived gray-scale median (GSM) of the most six distal portion of the occluded femoral-popliteal arterial segment can predict success of lumen re-entry for subintimal angioplasty. Methods During the last 3 years, 108 patients (62% men) with a mean age of 73 ± 10 years underwent 116 primary attempted DUS-guided subintimal angioplasties of the femoral-popliteal segment. Preprocedural B-mode DUS images of the plaque at the most distal occlusion segment were digitalized and normalized using Photoshop (Adobe, San Jose, Calif) software and standard criteria (gray level, 0 to 5 for lumen blood and 185 to 190 for the adventitia on a linear scale of 0 to 255). Overall GSM of the plaque segment about 2 cm long, immediately before the planned re-entry point to the true arterial lumen, was used for retrospective correlation with procedure success and other clinical indicators. Results Mean plaque GSM for all cases was 22.5 ± 12.6 (range, 3 to 60). The overall success rate of subintimal angioplasty procedures was 85%. Mean plaque GSM for 99 successful cases (18.4 ± 7.8) was significantly lower than for 17 cases (46.4 ± 8.1) where we failed ( P < .0001). We failed in 90% of 19 cases with GSM >35, in 71% of 24 cases with GSM >20, and in 50% of 34 cases with GSM >25. There was no statistically significant difference ( P = .45) between plaque GSM in 64 patients with diabetes (23.3 ± 13.5) compared with 52 nondiabetic patients (21.5 ± 11.4). Similarly, plaque GSM was not statistically different ( P = .9) in 52 patients with renal insufficiency (22.7 ± 13.2) compared with 64 patients with normal creatinine levels (22.4 ± 12.2). At the 6-month follow-up, no statistically significant difference was found between mean GSM (17.8 ± 7.8) in 47 stenosis-free cases compared with mean GSM (18 ± 6.8) in 22 cases where severe restenosis (>70%) or reocclusion was identified by DUS scan ( P = .4). Conclusions Plaque echogenicity represented by DUS-derived GSM can be used to predict the success of primary subintimal femoral-popliteal angioplasties.