201Tl perfusion study of "ischemic" ulcers of the leg: prognostic ability compared with Doppler ultrasound

Thallium 201 perfusion analysis was compared with Doppler ultrasound as a means of determining the healing potential of an ischemic ulcer of the leg in 27 patients. The degree of hyperemia was determined by comparative point counting of the 201Tl distribution in and about the ulcer. Using established Doppler criteria and a hyperemia ratio greater than 1.5:1, ultrasound alone correctly predicted healing in 15 out of 23 cases and 201Tl in 20 out of 23. Ultrasound correctly predicted non-healing in 3 out of 6 cases, compared with 5 out of 6 for 201Tl. The positive predictive value of the 201Tl study was 63%, versus 27% for ultrasound, and the negative predictive value was 95% for 201Tl and 83% for ultrasound. The accuracy of 201Tl and ultrasound was 86% and 62%, respectively. This limited study suggests that 201Tl perfusion scanning is a useful noninvasive test of ulcer healing potential and may be more sensitive than Doppler ultrasound.