Ventilation-perfusion lung scintigraphy as a guide for pulmonary angiography in the localization of pulmonary emboli

To assess the appropriateness of ventilation-perfusion (V-P) scintigraphic abnormalities as a guide to pulmonary angiography for the diagnosis of pulmonary embolism (PE).

V-P scintigrams and pulmonary angiograms of 104 patients with angiographically proved PE were reviewed by two nuclear medicine physicians and two interventional radiologists. For V-P scintigrams, the lung with the larger amount of perfusion abnormality was determined followed by identification of specific lobes. Pulmonary angiograms were similarly evaluated for lateralization and lobar distribution of PE. Conclusions were initially reached independently and subsequently by consensus.

Interobserver agreement for lateralization was 88% (kappa = 0.75) for V-P scintigraphy and 98% (kappa = 0.96) for pulmonary angiography. In 72 patients, V-P scintigrams predicted unilateral embolus; 64 patients underwent pulmonary angiography of the suspected side. Eight patients underwent contralateral angiography only. Of the 64 patients, 61 (95%) had PE on the predicted side at angiography. V-P scintigrams predicted lobar distribution in 55 patients. Of these, PE was found in the predicted lobe in 42 (76%).

Localization of perfusion abnormalities at V-P scintigraphy provides useful information for the interventional radiologist and serves as an accurate guide for determining the initial approach for pulmonary angiography.