Murine lung tumor measurement using respiratory-gated micro-computed tomography

Objective: The authors explored micro-computed tomography (micro-CT) to quantify lung tumor number and volume in a specific genetic mouse model for lung cancer. Materials and Methods: The authors used K-ras(LA1) mice, which develop lung adenomas and adenocarcinomas through somatic activation of the K-ras oncogene. Tumor number measured using micro-CT and were compared at necropsy (n = 38 mice). Tumor volume measurement precision (n = 39 mice) and accuracy (multiple tumors from a single mouse) were evaluated. Serial lung tumor volume was assessed in a pilot group (n = 8) of mice in vivo. Results: Tumor number assessed at necropsy and using micro-CT were significantly correlated. Lung tumor volume measurements were both reproducible (2% operator variability) and accurate (6% average error). Strikingly, we observed both tumor growth and shrinkage within individual mice. Conclusion: Serial measurements provided evidence of tumor heterogeneity, an unexpected finding given the uniformity of the initiating genetic event. Micro-CT may become a powerful tool for murine lung cancer research in vivo.