PREDICTION OF PULMONARY-FUNCTION AFTER RESECTION OF PRIMARY LUNG-CANCER - UTILITY OF INHALATION-PERFUSION SPECT IMAGING

To help determine whether preoperative perfusion and inhalation SPECT imagings are useful in predicting postoperative lung function, Tc-99m MAA perfusion SPECT imaging, CT scans, and pulmonary function tests we re prospectively performed in 33 patients with primary lung cancer bef ore and after lobectomy or pneumonectomy. Tc-99m Technegas inhalation SPECT imaging was performed in 6 of 33 patients as well. The authors a lso studied changes in radioactivity on the operated and nonoperated s ides before and after surgery, examined the lowest limit value for ada ptability to the operation, and made a comparison of both perfusion an d inhalation SPECT imaging. The predicted postoperative values obtaine d from the preoperative Tc-99m MAA SPECT images correlated more closel y with the measured 6-month postoperative values than with the measure d 8-month postoperative values. The highest correlation coefficient (r = 0.86) was observed between the predicted forced vital capacity (FVC ) value and the measured 6-month postoperative FVC value. In many case s, there was not a great difference between the 6-month and 6-month ra dioactivity on the operated side obtained from Tc-99m MAA SPECT images . This appears to indicate that pulmonary blood flow on the operated s ide has completely recovered by 3 months after surgery. However, radio activity in both the upper and lower lobes of the nonoperated side inc reased soon after surgery compared with that before the operation, and had not returned to preoperative levels 6 months after surgery. The r adioactivity in the right middle lobe did not change before and after surgery, The lowest limit value for adaptability to the operation was estimated to be 1.1 L for FVC and 900 ml for forced expiratory volume (FEV)(1.0). The predicted values obtained from both perfusion and inha lation SPECT studies closely approximated each other, making it diffic ult to determine which SPECT imaging was superior.