Helical computed tomography inaccuracy in the detection of pulmonary metastases: can it be improved?

In thoracic surgery, manual lung palpation for detection of pulmonary metastases during resection is the standard of care, despite improvements in computed tomography (CT) imaging. In our previous study based on chart review alone, the accuracy of helical CT in the detection of pulmonary metastases was surprisingly low, with a sensitivity of 78%. We hypothesized that this may be improved by scan interpretation with adequate clinical history and focused documentation of all pulmonary lesions, and may be influenced by the training of the reader.

Preoperative CT scans of 53 patients undergoing 60 cases of pulmonary metastasectomy at our center from 1996 to 2004 were retrospectively reviewed by a dedicated chest radiologist and a non-chest radiologist. Nodules detected on preoperative helical CT were compared with pathologically confirmed metastases.

In 27 of 59 (46%) cases read by radiologist 1, and 27 of 58 (47%) cases read by radiologist 2, metastases found by lung palpation were not seen on preoperative CT. Preoperative CT was entirely correct (no missed metastases or false-positive lesions) in only 11 of 59 (19%) of cases read by radiologist 1, and 11 of 58 (19%) of cases read by radiologist 2.

Helical CT misses metastases in 46% to 47% of cases. Accuracy of preoperative CT scanning for detection of pulmonary metastases was not improved with the provision of clinical history to the reader, nor was it influenced by the interpreter's training. A combined approach to pulmonary metastasectomy including preoperative and postoperative CT as well as manual lung palpation is necessary to render the patient disease-free.