Simultaneous isotope clearance from the muscles of the calf and thigh

There has been no end to the attempts made to determine the site and severity of arterial lesions in claudicants by the use of non-invasive methods but, so far, their diagnostic value has been limited. A method whose diagnostic accuracy in determining the site and functional severity of the lesions approaches that of arteriography is discussed. The hyperaemic index, which is the ratio of the total excess of blood supply during post-exercise hyperaemia over the maximum hyperaemic flow, has been determined in the thigh and calf simultaneously, by measuring the 99Tcm muscle clearance in 30 limbs of 20 healthy volunteers and 139 limbs of 145 patients with claudication. Lumbar arteriography classified the lesions in all patients as 0-10 per cent, 10-40 per cent, 40-70 per cent and more than 70 per cent stenosis. A bivariate analysis of the hyperamic indices of the thigh and calf determined the site and whether single lesions consisted of a stenosis greater or less than 70 per cent. In limbs with combined aorto-iliac and superficial femoral lesions the values of the hyperaemic indices could determine which of the two lesions was the more severe in addition to whether lesions consisted of a stenosis greater or less than 70 per cent. These findings have been confirmed in a further blind prospective study of 47 limbs in which determination of the site and severity of lesions preceded aortography.