Reproducibility of tumor volume measurement at MicroCT colonography in living mice

Rationale and Objectives. We sought to demonstrate the viability of microcomputed tomographic colonography (mu CTC) as a tool for monitoring tumorigenesis in mouse models of human colorectal cancer during prospective longitudinal studies. The precision and accuracy of volumetric measurements were determined to assess whether changes in tumor volume over time were readily detectable. Materials and Methods. All animal studies were conducted under the guidelines set forth by the Institutional Animal Care and Use Committee of the American Association for Assessment and Accreditation of Laboratory Animal Care. mu CTC was performed on C57BL/6J (B6) mice carrying the Min allele of Apc, ultimately yielding 18 scans. Assessments of scan quality and tumor volume were both performed once per week over 8 weeks. Results. Scans with a good quality rating had a mean standard deviation in tumor volume measurement of 8%. By contrast, scans with a poor quality rating had a mean standard deviation in tumor volume measurement of 35%. Variables affecting mu CTC scan quality in living mice included bowel preparation, motion artifact, and tumor morphology. Tumor volume measurements were highly correlated with tumor weight (r(2) = 0.87). Conclusions. The reproducibility of tumor volume measurement at mu CTC in living. mice makes prospective longitudinal evaluation of colonic tumor response feasible. For mu CTC scans of good quality, a 16% change in tumor volume can be detected at the 95% confidence level.