Mismatched perfusion defect on V/Q scan associated with PAPVC

1252 Learning Objectives 1. Present a case of V/Q scan findings of absent perfusion in the right upper lobe in a young adult with history of repaired ASD and PAPVC. 2. Review types of PAPVC and possible complications leading to perfusion defects. 3. Provide a list of common and uncommon differential diagnosis of mismatched perfusion defects on V/Q scan. The presence of partial anomalous pulmonary venous connection (PAPVC) is probably under diagnosed as most patients are asymptomatic. Depending on the severity of the condition, definitive treatment for PAPVC is surgical repair, which may lead to complications such as baffled obstruction. In this poster we present an incidental finding of a mismatched perfusion defect with normal ventilation on V/Q scan in a patient with history of PAPVC. The patient is a 31 year old female 14 weeks pregnant who presented with sudden onset of left sided pleuritic chest pain. Chest X-ray is normal. A V/Q scan shows a mismatched perfusion defect involving the entire right upper lobe. On the follow up chest CT, no identifiable venous drainage of the right upper lobe to the left atrium is identified. The heart is normal in size.The patient has a history of ASD and PAPVC, which was surgically repaired 10 years prior to the V/Q scan, with the right upper pulmonary vein sacrificed. The mechanism of perfusion defect will be discussed. The most common form of PAPVC is one in which a right upper pulmonary vein connects to the right atrium or the superior vena cava. This form is almost always associated with a sinus venosus type of ASD. Other types of PAPVC will be discussed. The types and the seririty of PAPVC may have varied findings on V/Q scan. A V/Q scan is primarily used to evaluate pulmonary embolism. The diagnosis is based on mismatched perfusion defects, which could also be seen with other causes, including the uncommon cause presented in this poster. Knowledge of common and uncommon causes of mismatched perfusion defects is important to trainees in nuclear medicine and radiology. The differential for mismatched perfusion defects on V/Q scan will be presented in this poster.