Abstract
Tumor volume is a parameter used to evaluate the performance of new therapies in lung cancer research. Conventional methods that are used to estimate tumor size in mouse models fail to provide fast and reliable volumetric data for tumors grown non-subcutaneously. Here, we evaluated the use of iodine-staining combined with micro-computed tomography (micro-CT) to estimate the tumor volume of ex vivo tumor-burdened lungs. We obtained fast high spatial resolution three-dimensional information of the lungs, and we demonstrated that iodine-staining highlights tumors and unhealthy tissue. We processed iodine-stained lungs for histopathological analysis with routine hematoxylin and eosin (H&E) staining. We compared the traditional tumor burden estimation performed manually with H&E histological slices with a semi-automated method using micro-CT datasets. In mouse models that develop lung tumors with well precise boundaries, the method that we describe here enables to perform a quick estimation of tumorous tissue volume in micro-CT images. Our method overestimates the tumor burden in tumors surrounded by abnormal tissue, while traditional histopathological analysis underestimates tumor volume. We propose to embed micro-CT imaging to the traditional workflow of tumorous lung analyses in preclinical cancer research as a strategy to obtain a more accurate estimation of the total lung tumor burden.
Highlights
Over the years, researchers have benefited enormously from genetically engineered mouse models for lung cancer[1,2,3,4]
We evaluated the use of contrast agent-based X-ray microtomography for the quantification of lung cancer volume in experimental mice
We evaluated the tumor burden using a semi-automated method, that uses grey-level threshold and region-grow algorithms to segment out the anatomic structures of interest in the 3D micro-CT images
Summary
Researchers have benefited enormously from genetically engineered mouse models for lung cancer[1,2,3,4] These models closely resemble the human pathology[5,6], providing a deep understanding of the steps involved in the progression of the disease. Very recently, staining of soft-tissue samples combined with X-ray absorption micro-computed tomography (micro-CT) has been demonstrated to be a beneficial tool for imaging soft-tissue biological specimens[27,28,29,30,31] This method has been mostly applied to anatomical studies[30,31,32,33] and provides non-distorted 3D highly-resolved micro-CT images of organs or parts of mammals[30,34]. We applied our method to a total of four pathogenic specimens and we discuss its advantages and limitations for tumor bulk evaluation comparing it to the histopathological tumor burden analysis performed with hematoxylin and eosin-stained (H&E) slices
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