單側肺動脈缺失是一個罕見的肺血管異常，它通常合併其他心?結構異常。我們報告一病例?九歲女性診斷?單獨的左側肺動脈缺失併右主動脈弓，此外這病例並無合併其他心?結構異常。一系列影像檢查包括：胸部X光、食道X光攝影、心?超音波、胸部斷層掃描、通氣及灌流掃描、心導管血攝影、三度空間核 磁共振血管攝影。由一張左右肺不對稱的胸部X光，開啟一連串後續檢查。心導管及肺動脈血管攝影診斷?左側且動脈缺失，核磁共振血管攝影是一有效的非侵襲性檢查，它確定地證明左肺動脈缺失且無陷藏的且動脈。因此手術建立部血流連續是不可能的。

Unilateral absence of a pulmonary artery (UAPA) is a rare pulmonary vascular anomaly that is usually associated with other cardiac anomalies. We report a 9-year-old female diagnosed with isolated unilateral absence of the left pulmonary artery and a right aortic arch but without other cardiac anomalies. The only symptoms the patient had were recurrent respiratory tract infections. The chest x-rays showed asymmetric lung fields, prompting subsequent studies. A series of imaging studies including chest x-rays, esophagography, echocardiography, chest computed tomography, lung ventilation-perfusion scintigraphy, angiocardiography, and 3-dimensional magnetic resonance angiography (3D-MRA) were done. The diagnosis was confirmed by the cardiac catheterization and pulmonary angiography, which disclosed absence of the left pulmonary artery. 3D-MRA conclusively demonstrated total absence of the left pulmonary artery without an occult left pulmonary artery or systemic-to-pulmonary collateral arteries. Therefore, surgical re-establishment of pulmonary continuity was impossible.