Quantification of Tumor Burden in a Genetically Engineered Mouse Model of Lung Cancer by Micro-CT and Automated Analysis

Abstract

Genetically engineered mouse models (GEMMs) of lung cancer closely recapitulate the human disease but suffer from the difficulty of evaluating tumor growth by conventional methods. Herein, a novel automated image analysis method for estimating the lung tumor burden from in vivo micro-computed tomography (micro-CT) data is described. The proposed tumor burden metric is the segmented soft tissue volume contained within a chest space region of interest, excluding an estimate of the heart volume. The method was validated by comparison with previously published manual analysis methods and applied in two therapeutic studies in a mutant K-ras GEMM of non–small cell lung carcinoma. Mice were imaged by micro-CT pre-treatment and stratified into four treatment groups: an antibody inhibiting vascular endothelial growth factor (anti-VEGF), chemotherapy, combination of anti-VEGF and chemotherapy, or control antibody. In the first study, post-treatment imaging was performed 4 weeks later. In the second study, mice were scanned serially on a high-throughput scanner every 2 weeks for 8 weeks during treatment. In both studies, the automated tumor burden estimates were well correlated with manual metrics (r value range: 0.83-0.93, P < .0001) and showed a similar, significant reduction in tumor growth in mice treated with anti-VEGF alone or in combination with chemotherapy. Given the fully automated nature of this technique, the proposed analysis method can provide a valuable tool in preclinical drug research for screening and randomizing animals into treatment groups and evaluating treatment efficacy in mouse models of lung cancer in a highly robust and efficient manner.

Longitudinal microcomputed tomography-derived biomarkers for lung metastasis detection in a syngeneic mouse model: added value to bioluminescence imaging

“…We detected that lung metastasis in our model was very diffuse and spread throughout the lungs in contrast to clearly delineated lung tumors in previous reports. [19][20][21][22] We therefore delineated the complete lungs to quantify the volume of hyperintense and hypointense signal via overall thresholding within the lung to quantify tumor mass and aerated lung volume, respectively. The aerated lung volume quantifies the air content of the lungs and probably best corresponds to the vital lung function.…”

“…μCT biomarkers of lung metastasis E Marien et al which is novel compared with previous reports where clearly delineated lung tumors or nodules were studied [20][21][22][23] and where μCT only contributed anatomical information of the lungs. 25 Moreover, quantification of live 3D imaging of metastasis is much more accurate, efficient, and useful compared with quantification of gold standard 2D ex vivo readouts at a single time point.…”

Noninvasive Bioluminescence Imaging of AKT Kinase Activity in Subcutaneous and Orthotopic NSCLC Xenografts: Correlation of AKT Activity with Tumor Growth Kinetics

“…Hence, the applied noninvasive approach saves both time and animals in pharmacokinetic and pharmacodynamic studies of preclinical drug efficacy. The tumor growth in the lungs was quantified indirectly by measuring the residual lung-air volume with micro-CT, which was described previously as a method by other studies [35], [36]. This anatomical readout is needed to interpret the orthotopic BLI signals as they are dependent of the AKT inhibition and the overall tumor load.…”

A step towards valid detection and quantification of lung cancer volume in experimental mice with contrast agent-based X-ray microtomography

“…Over the years, researchers have benefited enormously from genetically engineered mouse models for lung cancer 1–4 . These models closely resemble the human pathology 5,6 , providing a deep understanding of the steps involved in the progression of the disease. Additionally, these mouse models are used to study the response and resistance to innovative therapies to treat cancer in studies of lung carcinogenesis with experimental mice 1,5–10 .…”

“…Histologic analysis is a well-established approach used in the clinics for the examination and diagnosis of cancer types in diseased lung tissues, and it is the standard tumor size measuring method when caliper measurements fail. Histopathological investigation of the tumorous lungs is done ex vivo 5,13 and tumor burden is determined by the percentage of total lung area occupied by the tumorous tissue in a histologic slice 2 . Histopathology involves tedious time-consuming manipulation of the specimen, which is cut into thin slices, stained and inspected in an optical microscope.…”