Comparison between exercise whole body thallium imaging and ankle-brachialindex in the detection of peripheral arterial disease

Background. Exercise whole body thallium imaging and rest/exercise ankle-br achial index can provide evidence of peripheral artery disease at the stage of intermittent claudication. The aim of this study was to compare both me thods in the detection of asymptomatic peripheral artery disease. Methods. Experimental design: prospective non-randomised study. Setting and patients: general community, private practice, ambulatory patients referre d in a Nuclear Medicine Department for exercise myocardial scintigraphy. In termittent claudication was present in 8% of the whole study population. Co ronary artery disease and diabetes were respectively present in 70% and 16% of the same population. Measures: rest/exercise ankle-brachial index and e xercise whole body thallium imaging were measured in 105 patients (76 men a nd 29 women, mean age +/- 1 SD= 61 +/- 10 year) who per formed a near-maxim al or maximal treadmill test. Normal values of regional blood supply and in dices of asymmetry at different levels of legs were determined in 14 patien ts with a very low probability of peripheral artery disease. Results. The probability of peripheral artery disease was very high in 19 p atients (group 1), because of abnormal rest and/or exercise ankle-brachial index, whereas in the 86 remaining patients, the index at rest and exercise was quite normal (group 2).With respect to rest and/or exercise ankle-brac hial index, the sensitivity, specificity, positive and predictive negative value of exercise scintigraphy abnormalities were respectively 89% 62%, 34% and 96%. The false positive scan group differed from the true positive gro up only by sex and redistribution of thallium 201. The proportion of diabet ic patients was the same (15%) in both groups. Conclusions. Exercise whole body thallium imaging might contribute without additional cost to the detection, functional evaluation and/or risk stratif ication of peripheral artery disease in patients who perform exercise myoca rdial scintigraphy.