COMPARISON OF WHOLE-BODY THALLIUM IMAGING WITH TRANSCUTANEOUS PO2 IN STUDYING REGIONAL BLOOD-SUPPLY IN PATIENTS WITH PERIPHERAL ARTERIAL OCCLUSIVE DISEASE

Quantitatively estimating functional reserve of blood supply to the le gs in patients with peripheral arterial occlusive disease (PAOD) remai ns a clinical issue. This study was designed to investigate the region al blood supply to the legs in PAOD patients during exercise by use of thallium 201 ((201)T1) whole-body imaging in comparison with transcut aneous PO2 (tcPO(2)) measurement. Thirty-three patients with PAOD and 10 subjects without PAOD (control) performed an incremental cycle ergo metry (CE), while tcPO(2) was continuously registered on the involved calf. In the last minute of exercise, 2 mCi of (201)T1 was injected in travenously and the (201)T1 whole-body images were taken immediately ( stress) and four hours (redistribution) following stress with a dual-h ead camera system. Regional blood supply (RES) (%) was calculated from the geometric mean counts of the region of interest divided by the to tal counts of the whole body. The performance of PAOD patients was red uced in doing CE, and tcPO(2) fell distinctly in PAOD patients (from 5 1 to 19 mmHg) whereas it increased in controls (from 57 to 67 mmHg). T he RES in PAOD patients was obviously reduced in comparison with that of controls. While in controls the RES of the calf (3.1%) at stress di d not differ from that at redistribution (3.4%), in PAOD patients the redistribution RES (2.8%) increased as compared with that of stress (1 .5%). There was a hyperbolic relationship between stress RES of the ca lf and the velocity of tcPO(2) fall in PAOD patients during exercise t est (velocity of tcPO(2) fall = -0.032 + 0.39/RBS, r(2) = 0.54, P < 0. 05). In conclusion, the RBS determined by (201)T1 whole-body imaging i s comparable to the tcPO(2) measurement in differentiating patients wi th PAOD from subjects without PAOD during exercise. Regional (201)T1 u ptake reflects regional blood supply in PAOD patients. There is a hype rbolic relationship between the RBS derived from (201)T1 whole-body im aging and tcPO(2) in PAOD patients during exercise, implying that in a critical ischemia the lower the RES is, the more steeply the tcPO(2) decreases.