Diagnostic value of Tc-99m MAA radionuclide venography of lower extremity: as a simultaneous procedure of ventilation-perfusion scan for pulmonary embolism.

Abstract

A total of 336 cases received a ventilation-perfusion(V/Q) scan for the detection of pulmonary embolism (PE). Among these, 155 cases simultaneously underwent a successful radionuclide venography study (RNV) of the lower limbs using Tc-99m macro-aggregated albumin (MAA). Concomitant pulmonary arteriography (PA) was performed in 120 cases. Fifty-four of these 120 cases successfully completed the RNV scan. There was a statistical significance in the V/Q scan for the detection of PE as confirmed by the PA (p less than 0.0001). The positive predictive value (PPV) of the RNV for PE was 75% (3/4). The negative predictive value (NPV) was 48% (24/50). The sensitivity and specificity were 10% (3/29) and 96% (24/25) for the 54 patients who had both the RNV scan and PA. For the 155 patients who had simultaneous V/Q and RNV scans, there was no statistically significant correlation between these two scans. The PPV, NPV, specificity and sensitivity were 42%(8/19), 75%(103/136), 90%(103/114) and 20%(8/41), respectively. Despite the low sensitivity and no significance of positive RNV for diagnosis of PE, RNV is still recommendable because it is a simple, non-invasive, simultaneous procedure during perfusion lung scan and has high specificity.