Role of lung scanning in assessing the resectability of bronchial carcinoma.

Ventilation and perfusion lung scans were performed in 58 patients before operation for bronchial carcinoma to determine in which patients the lung scan was most useful for assessing mediastinal spread and resectability of the tumour. Perfusion of the affected lung was less with larger and more centrally situated tumours. Perfusion was also less for left-sided than for right-sided tumours but this is explained by the normal differential perfusion of the right and left lungs. The lung scan was unhelpful in predicting resectability of peripheral tumours, but with central tumours if perfusion of the affected lung was less than 25% of the total perfusion the lesion was likely to be non-resectable because of spread to the mediastinum. Airways obstruction was present in 67% of the patients but did not interfere with the interpretation of the scans. In most cases ventilation scans provided no additional information, and the use of krypton-81 m as a sensitive indicator of regional ventilation did not improve on the predictive value of the perfusion scan.