Ventilation-perfusion scan in the acutely ill patient with unilateral hyperlucent lung.

A patient with a unilateral hyperlucent lung with acute respiratory complaints is presented. A ventilation-perfusion scan was performed to rule out pulmonary embolism. The perfusion scan ( [99mTC]MAA) showed peripheral perfusion defects in the hyperlucent lung. The ventilation study (133Xe) demonstrated peripheral ventilatory defects on the single breath image in the hyperlucent lung, the filling in of these on the equilibrium view, and diffusely delayed washout in the affected lung. These findings were suggestive of the Swyer-James syndrome and critical in excluding the numerous other causes of unilateral hyperlucent lung, which are discussed. The importance of the ventilation-perfusion study (and particularly the ventilation scan) in the patient with unilateral hyperlucent lung and acute respiratory symptoms is stressed. In addition, a discussion of the Swyer-James syndrome is included.