Non-embolic causes of perfusion defects on VQ scan.

Conclusions:When reviewing a VQ scan, it is important to consider both embolic and non-embolic causes of perfusion defects. Correlation with the chest radiograph should be made and further evaluation with cross sectional imaging obtained when appropriate. Patients who have a massive pulmonary embolism are typically too unstable to undergo a VQ scan. Therefore, a unilateral lobar or whole lung perfusion defect should prompt further evaluation for a non-embolic cause, such as a compressing mass or a congenital anomaly. Mediastinal masses, such as bronchogenic carcinoma or lymphoma, are a common cause for pulmonary artery obstruction due to external compression. Additionally, endobrochial lesions which obstruct the bronchus can cause a ventilation defect with a compensatory decrease in perfusion to the corresponding lung segment resulting in a matched perfusion defect on VQ scan.
Source: Journal of Nuclear Medicine - Category: Nuclear Medicine Authors: Tags: Educational Exhibits Source Type: research