Perfusion lung scintigraphy for the prediction of postoperative residual pulmonary function in patients with lung cancer

BACKGROUND: Accurate prediction of postoperative pulmonary function in patients with non-small cell lung cancer is crucial for proper qualification for surgery, the only effective therapeutic method. The aim of the study was to select the most accurate method for acquisition and processing of lung perfusion scintigraphy (LPS) combined with spirometry for prediction of postoperative pulmonary function in patients qualified for surgery. MATERIAL AND METHODS: LPS was performed in 70 patients (40 males, 30 females), with preoperative spirometry (mean FEV1preop = 2.26 ± 0.72 L), after administration of 185 MBq of 99mTc-microalbumin/macroaggregate, using planar (appa) and SPECT/CT methods. Predicted postoperative lung function (FEV1pred) was calculated as a part of active lung parenchyma to remain after surgery. A non-imaging segment counting method was also applied. FEV1pred(appa, SPECT, SPECT/CT, segm.) were further compared with actual FEV1postop values obtained from postoperative spirometry. RESULTS: In the whole studied group (47 lobectomies, 23 pneumonectomies) mean value of FEV1postop was equal to 1.76 (± 0.56) L. FEV1pred(appa, SPECT, SPECT/CT, segm.) were equal to 1.75 (± 0.58) L, 1.71 (± 0.57) L, 1.72 (± 0.57) L and 1.57 (± 0.58) L, respectively. A segment counting method systematically lowered predicted FEV1 values (p < 10–5). Moreover, in 31 patients with FEV1preop < 2 L error of predicted values was assessed with Bland-Altman method. Mean absolute differences FEV1postop – FEV1pred amounted to: appa — (0.04 ± 0.13) L, SPECT — (0.07 ± 0.14) L, SPECT/CT — (0.06 ± 0.14) L and segm. — (0.21 ± 0.19) L, respectively. Lower limit of 95% confidence interval calculated for planar — optimal method, was equal to –220 mL (also determined separately in subgroups after lobectomy and pneumonectomy). CONCLUSIONS: This study shows that planar LPS may be applied for prediction of postoperative pulmonary function in patients qualified for pneumonectomy and lobectomy. If actual FEV1postop value is to be ≥ 800 mL, predicted value should exceed 1000 mL