Comparison between quantitative computed tomography, scintigraphy, and anatomical methods for prediction of postoperative FEV(1) and DLCO: effects of chronic obstructive pulmonary disease status and resected lobes

BACKGROUND: Postoperative assessment of pulmonary function is important for estimating the risk of thoracic surgery and long-term disability following pulmonary resection, including predicted postoperative (ppo) forced expiratory volume (FEV) in one second (ppoFEV(1)) and percent predicted lung diffusion capacity for carbon monoxide (ppo%DLCO) estimation. The ppo values were compared using four different estimation methods between chronic obstructive pulmonary disease (COPD) and non-COPD patients and according to the resected lobe. METHODS: This prospective study included 59 eligible patients requiring single lobectomy and succeeded in performing pulmonary function tests at 3 and 12 months after lobectomy. The ppoFEV(1) and ppo%DLCO were compared with poFEV(1) and po%DLCO obtained at 3 and 12 months after lobectomy. The ppo values were estimated using the four usual methods: the 19-segment anatomical technique (S), perfusion scintigraphy (Q), quantitative CT (CT), and quantitative CT with low attenuation volume (CT(LAV)) subtraction. RESULTS: For non-COPD and COPD patients, the smallest mean difference between ppo and po values was observed by S for FEV(1) and %DLCO. Based on the resected lobe, the smallest mean difference was observed by (I) Q for right upper lobectomy (RUL) excluding %DLCO at 12 months by S, (II) S for left upper lobectomy (LUL), (III) CT and CT(LAV) for right lower lobectomy (RLL), and (IV) CT and CT(LAV) for left lower lobectomy (LLL) at 12 months. The ppo values calculated by S for RUL (FEV(1) at 3 and 12 months and %DLCO at 3 months) and by all four methods for LLL (FEV(1) and %DLCO at 3 months) were smaller than the po values. CONCLUSIONS: The S method is adequate for calculating ppoFEV(1) and ppo%DLCO when patients are classified as non-COPD and COPD. However, S sometimes overestimates the ppoFEV(1) and ppo%DLCO when patients are classified according to the resected lobe. The CT(LAV) method may be the method of choice instead of S for calculating ppoFEV(1) and ppo%DLCO in patients who undergo lung lobectomy despite the presence or absence of airflow limitation.