Precision of computer-aided volumetry of artificial small solid pulmonary nodules in ex vivo porcine lungs

The purpose of this study was to investigate the precision of CT-based volumetric measurements of artificial small pulmonary nodules under ex vivo conditions. We implanted 322 artificial nodules in 23 inflated ex vivo porcine lungs in a dedicated chest phantom. The lungs were examined with a multislice spiral CT (20 mAs, collimation 16 x 0.75 mm, 1 mm slice thickness, 0.7 mm increment). A commercial volumetry software package (LungCARE VA70C-W; Siemens, Erlangen, Germany) was used for volume analysis in a semi-automatic and a manual corrected mode. After imaging, the lungs were dissected to harvest the nodules for gold standard determination. The volumes of 202 solitary, solid and well-defined lesions without contact with the pleura, greater bronchi or vessels were compared with the results of volumetry. A mean nodule diameter of 8.3 mm ( +/- 2.1 mm) was achieved. The mean relative deviation from the true lesion volume was -9.2% ( +/- 10.6%) for semi-automatic and -0.3% ( +/- 6.5%) for manual corrected volumetry. The subgroup of lesions from 5 mm to <10 mm in diameter showed a mean relative deviation of -8.7% ( +/- 10.9%) for semi-automatic volumetry and -0.3% (+/- 6.9%) for manually corrected volumetry. We conclude that the presented software allowed for precise volumetry of artificial, nodules in ex vivo lung tissue. This result is comparable to the findings of previous in vitro studies.