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

Background: Exercise whole body thallium imaging and rest/exercise ankle-brachial index can provide evidence of peripheral artery disease at the stage of intermittent claudication. The aim of this study was to compare both methods in the detection of asymptomatic peripheral artery disease.

Experimental Design: prospective non-randomised study.

Setting And Patients: general community, private practice, ambulatory patients referred in a Nuclear Medicine Department for exercise myocardial scintigraphy. Intermittent claudication was present in 8% of the whole study population. Coronary artery disease and diabetes were respectively present in 70% and 16% of the same population.

Measures: rest/exercise ankle-brachial index and exercise whole body thallium imaging were measured in 105 patients (76 men and 29 women, mean age +/- 1 SD= 61 +/- 10 year) who performed a near-maximal or maximal treadmill test. Normal values of regional blood supply and indices of asymmetry at different levels of legs were determined in 14 patients with a very low probability of peripheral artery disease.

Results: The probability of peripheral artery disease was very high in 19 patients (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-brachial 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 group only by sex and redistribution of thallium 201. The proportion of diabetic 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 stratification of peripheral artery disease in patients who perform exercise myocardial scintigraphy.