Pulmonary Nodules: Preliminary Experience with Semiautomated Volumetric Evaluation by CT Stratum

Rationale and Objectives To evaluate the performance of custom-made software designed to quantify volume and weight of focal portions of lung tumors in regions of interest (ROI) and volume of interest on thin-section computed tomography (CT) images by stratum of CT values. Methods and Materials Volume and weight of lung portions were measured three-dimensionally and semiautomatically by CT stratum and compared with standard manual measurements. One each of a partly solid tumor (including initial and follow-up high-resolution CT scans), partly solid tumor with most parts showing solid density, and nonsolid tumors in the mid-zone of the lung were analyzed. The doubling time (DT) of tumor volume and mass were calculated by stratum of CT values. Results The software-measured tumor weight in lung periphery was reproducible, with and without trimming of intervening lung structures between borders of ROIs and tumor. For the lesion in the midlung zone, the fairly thick nearby pulmonary vessels degraded the measurements, with a higher measurement error, indicating the need to trim these structures off the ROI. Software measurements allowed quantification of tumor progress based on increase in tumor mass, without significant increase in tumor volume. The DTs for both tumor volume and mass were different among the four strata of CT values in the partly solid nodule. Conclusion Our semiautomated volumetric method involving measurement by CT stratum is promising for evaluation of lung tumor progress and aggressiveness.