Helical CT of pulmonary modules in patients with extrathoracic malignancy:CT - Surgical correlation

OBJECTIVE. Our aim was to assess the sensitivity of helical CT for revealin g pulmonary nodules. Thoracotomy with palpation of the deflated lung, resec tion, and histologic examination of palpable nodules was used as the gold s tandard. SUBJECTS AND METHODS. Thirteen patients underwent helical CT (slice thickne ss, 5 mm; reconstruction intervals, 3 mm and 5 mm; interpreted by two indep endent observers). Subsequently, patients underwent unilateral (n = 6) or b ilateral (n = 7) surgical exploration, and CT-surgical correlation of 20 lu ngs was performed. RESULTS. Ninety nodules were resected (61 were smaller than 6 mm; 13 were 6 -10 mm; 11 were larger than 10 mm; in five nodules, the size was not record ed at surgery). Sixty-nine nodules were located in the pulmonary parenchyma and 21 in the visceral pleura. Of the 90 lesions, 43 (48%) were found on h istology to represent metastases. For lesions detected by at least one obse rver, the sensitivity of helical CT was 69% for intrapulmonary nodules smal ler than 6 mm, 95% for intrapulmonary nodules larger than or equal to 6 mm, and 100% for histologically proven intrapulmonary metastases larger than o r equal to 6 mm. For lesions smaller than or equal to 10 mm, sensitivity wa s better using a reconstruction interval of 3 mm rather than of 5 mm. CONCLUSION. In this study, the sensitivity of helical CT exceeded the sensi tivity of conventional CT in previous reports. However, because of limitati ons in the detection of intrapulmonary nodules smaller than 6 mm and of ple ural lesions, complete surgical exploration should remain the procedure of choice in patients undergoing pulmonary metastasectomy. Preoperative helica l CT should be used to guide the surgeon to lesions that are difficult to p alpate.