Ultrasonic plaque character and outcome after lower limb angioplasty

Purpose: The value of ultrasonic plaque characteristics in identifying pati ents at "high-risk" of restenosis after percutaneous transluminal angioplas ty (PTA) was studied. Methods: Thirty-one arterial stenoses (6 common iliac, 2 external iliac, 1 profundafemoris, 21 superficial femoral, and 1 popliteal) in 17 patients wh o underwent angioplasty were studied by means of duplex scanning. With a co mputer-based program, B-mode images were digitized and normalized using 2 r eference points, blood and adventitia. A grey level of 0 to 5 was allocated for the lumen (blood) and 180 to 190 for the adventitia on a linear gray s cale of 0 to 255 (0 = absolutely black; 255 = absolutely white), and the ov erall plaque gray-scale median (GSM) of the pixels of the plaque was used a s a measure of plaque echodensity. After PTA, follow-up of stenoses was don e on day 1, weekly for 8 weeks, at 3 months, 6 months, and 1 year. The tota l plaque thickness (sum of anterior and posterior components), minimal lumi nal diameter (MLD), and peak systolic velocity ratio (PSVR) were measured f or all stenoses. An increase of more than 2 in the PSVR was the duplex crit erion used to signify restenosis. Results: The GSM of the stenoses before angioplasty ranged from 6 to 71 (me an, 31.3 +/- 17.9); 17 stenoses had a GSM less than 25 (mean, 18.7 +/- 5.3) , and 14 had a GSM more than 25 (mean, 46.4 +/- 15.8). When the GSM was les s than 25, the absolute reduction in plaque thickness on day 1 post-PTA was 3.3 +/- 1.8 mm, in contrast to 1.8 +/- 1.6 mm when GSM was more than 25 (P <.03). The restenosis rate (PSVR more than 2) was 41% at 6 months and rema ined unchanged at 1 year When the GSM was less than 25, restenosis occurred in 11% of lesions, in comparison with 78% when the GSM was more than 25 (P <.001). Conclusion: Plaque echodensity can be used to evaluate stenoses before PTA, to predict initial success and identify a subgroup that has a high prevale nce of restenosis. The identification of a group at "high-risk" of restenos is can improve the selection of patients for the procedure and also be used in prospective studies on the prevention of restenosis.