Computed tomography of the calves. A screening procedure in the diagnosis of unilateral thrombosis of the deep veins of the lower limbs.
A prospective study of twelve patients, referred to the Department of Radiology of the University Hospital of the West Indies between March, 1990 and November, 1991 with a clinical diagnosis of deep vein thrombosis, was undertaken. All patients had computed tomography of the calves, as well as venography of the affected limb. Six patients (50%) had positive venograms. Of these, five had a difference of greater than 10% between the areas of the muscular compartments of the two limbs. Six patients had negative venograms but only three demonstrated a difference of a similar magnitude. The ratios of the area of the muscular compartment to the total limb area were also compared. Two of the six patients with positive venograms showed a greater ratio in the affected limb. One of the six patients with negative venograms showed a greater ratio in the affected limb. In this study, 83.3% of patients who did not have thrombosis of the deep veins of the calves had a ratio of muscular area to total limb area that was less than or equal to that of the unaffected side. This latter finding provides a potentially useful means of screening patients referred for venograms.