Accuracy of helical CT in the detection of pulmonary metastases: is intraoperative palpation still necessary?

Background: Pulmonary metastasectomy is well accepted in patients with isolated metastases from an extrathoracic malignancy. The standard approach involves careful intraoperative palpation of the lungs because more metastases are frequently found than were seen by preoperative conventional computed tomography (CT). Helical CT detects more nodules than conventional CT, raising the question of whether palpation of the lungs is still necessary if helical CT is used.

Methods: Retrospective review was done of medical records of patients undergoing metastasectomy with curative intent at the University of North Carolina (UNC) from 1999 to 2003. During this time at UNC, helical CT was routinely performed using a standardized technique, and all metastasectomy patients underwent manual lung palpation. The primary outcome measure of this study was whether malignant nodules (palpated, resected, and proven histologically) were reliably detected preoperatively by helical CT.

Results: Thirty-four patients were identified who underwent 41 cases of pulmonary metastasectomy with lung palpation. Our analysis revealed that in 22% (9/41), more malignant nodules were found intraoperatively than were detected by helical CT. Of 88 malignant intraparenchymal nodules, 69 were detected by helical CT (sensitivity 78%). Subset analyses of tumor histology, disease-free interval, the presence of a single lesion versus multiple lesions, the interval between the CT and metastasectomy, and the size of the largest lesion were unable to identify a cohort in which lung palpation was no longer needed after preoperative helical CT.

Conclusions: Despite the advent of helical CT, palpation of the lung is necessary if the goal is to resect all detectable disease.