Non-small-cell lung cancer dimensions: CT-pathological correlation and interobserver variation.

The aim of the study was to identify the most accurate CT window level setting for the measurement of non-small-cell lung cancer to optimise CT planning for radiotherapy treatment. 27 patients who underwent resection for non-small-cell lung cancer in a single institution were studied. The maximal superior-inferior, anteroposterior and mediolateral dimensions of the resected tumours were measured by a consultant pathologist. Two radiologists made corresponding measurements using pre-operative CT scans independently of each other and of the pathologist's findings. The measurements were obtained using four different CT window settings. The mean pathological size of the superior-inferior tumours, the anteroposterior tumours and the mediolateral tumours was 32 mm, 28 mm and 25 mm, respectively. A total of 648 CT measurements were taken, of which 321 were within +/- 5 mm of the pathological size (49.5%). There was significant interobserver variability between the two radiologists. There was poor correlation between the pathological and radiological measurements of tumour size. Significant interobserver variability was noted between the two radiologists and no window setting could be identified as being superior in accurately assessing the tumour size.