Lower-limb Vascularization in Diabetic Patients. Assessment by Thallium-201 Scanning Coupled with Exercise Myocardial Scintigraphy

Objective: To investigate, by thallium-201 scanning, circulation in the muscles of the lower limb (LL) in diabetic patients without clinical peripheral vascular disease but with a high cardiovascular risk profile.

Research Design And Methods: A total of 80 diabetic patients (76 patients with type 2 diabetes, mean age 57.3 years, duration of diabetes 13.0 +/- 7.5 years) with more than one additional cardiovascular risk factor but no claudication were investigated. After stress testing, 1.5 MBq/kg thallium-201 was administered to perform myocardial single-photon emission computed tomography followed by LL scanning. Muscle blood flow was considered abnormal if the asymmetry in thallium-201 uptake between the two buttocks and/or thighs and/or calves was > 10%.

Results: Muscle perfusion defects were found in 42% of the patients, mainly in the calves. These defects correlated with retinopathy (P = 0.042) and the HbA1c level (P = 0.044). In patients with defects in the buttock and/or thigh, the prevalence of nephropathy and retinopathy was higher than in those with isolated defects in the calf (P = 0.032 and 0.023, respectively).

Conclusions: This study suggests that LL scanning coupled with myocardial scintigraphy is a convenient method of investigating peripheral muscle circulation. Proximal perfusion defects in patients without clinical arterial disease are associated with increased prevalence of retinopathy and nephropathy and, therefore, may be due to microvascular disease of LL muscle. Distal defects may indicate silent macrovascular disease of the LL.