Pulmonary nodules: 3D volumetric measurement with multidetector CT--effect of intravenous contrast medium

To retrospectively evaluate the effect of contrast medium on the three-dimensional volumetric measurement of pulmonary nodules.

The study was approved by the local institutional review committee, with waiver of informed consent. Sixty pulmonary nodules in 60 patients (17 women, 43 men; age range, 29-82 years) were imaged before and after administration of contrast medium with a 64-channel multidetector computed tomographic (CT) scanner; reconstructed images with a section thickness of 0.625 mm were obtained by using a bone algorithm and a standard algorithm. Volumetric measurements of pulmonary nodules were performed by using commercially available software, and the postcontrast volume ratio was calculated by dividing the postcontrast volume by the precontrast volume. Precontrast and postcontrast volumes were then analyzed by using a Wilcoxon signed rank test.

The median measured volumes of pulmonary nodules were 817 mm(3) (precontrast imaging, bone algorithm), 887 mm(3) (postcontrast imaging, bone algorithm), 812 mm(3) (precontrast imaging, standard algorithm), and 855 mm(3) (postcontrast imaging, standard algorithm). The measured volumes obtained with the bone algorithm were significantly larger than those obtained with the standard algorithm, both before and after administration of contrast medium (P < .01); with both the standard algorithm and the bone algorithm, the measured postcontrast volumes were significantly larger than the precontrast volumes (P < .01). The postcontrast volume ratio was more than 1.0 in 45 cases (75%) when the bone algorithm was used and in 53 cases (88%) when the standard algorithm was used. The mean postcontrast volume ratio was 1.054 with the bone algorithm and 1.065 with the standard algorithm.

The measured volume of pulmonary nodules obtained by using three-dimensional volumetric software increased after administration of contrast medium. Moreover, the measured volume of pulmonary nodules that was obtained with the bone algorithm was larger than that obtained with the standard algorithm, regardless of whether contrast medium was used.