P2-10-05: Cryo-Microcomputed Tomography (CT) with Synchrotron Radiation: Visualization of Human Breast Cancer Tissue and Comparison with Their Histopathologic Findings.
Authors: Jeong Y-J , Jeong H-Y , Bong J-G , Park S-H , Kim H-T , Kim J-K , Huang J-Y 
Published: June 2012

Background: A synchrotron radiation (SR)-based X-ray source offers a powerful tool for diagnosis of breast disease due to the energy spectrum properties and the peculiar laminar beam geometry. The aims of this study were to estimate the visualization of the human breast cancer tissue with SR cryo-micro CT and to compare the results with histopathological examinations.

Material and Methods: The cancerous breast tissue samples were routinely fixed in 10% neutral buffered formalin, and each specimen was cut down to a cylindrical sample with 2 mm diameter and 10 mm height. Each breast cancer sample was rapidly frozen with dry ice, mounted on a computer-controlled precision stage and maintained at cryogenic temperature throughout data collection. Experiments were performed at the bending magnet beamline 7B2 of Pohang Light Source (PLS) in Accelerator Laboratory (PAL) which is a third-generation SR facility with 2.5 GeV operating energy. The white beam imaging system developed for synchrotron tomography consists of a 1 mm Si attenuator, 100 μm-thick CdWO4 scintillator and a full-frame charge-coulped device camera. The detector is placed 10 mm downstream from the sample on an optical table which can be rotated in the fan beam about a vertical axis for tomography. For tomography, images were collected at 0.18° increments through 180°. The visual image was magnified using a 20x microscope objective and captured using a digital CCD camera. The spatial resolution determined by standard sample was about 1.5 μm. Three-dimensional volume images of the specimen were obtained by applying a filtered back-projection algorithm to the projection images using a software package OCTOPUS. Surface reconstruction and volume segmentation and rendering were performed using Amira software. After imaging the samples were split into several sections, processed and embedded in paraffin. Obtained tomography images were compared with corresponding histopathological findings in optical microscopy.

Results: A total of 1000 synchrotron tomography images were acquired from the samples and only a small number of different typical cases were selected for a detailed analysis. The correspondence between tomography images and histopathological findings were determined. Synchrotron tomography images yield high contrast from smoothly varying internal structures corresponding to information on actual structures seen at histopathological analysis.

Discussion: Since the projection of 3D anatomic information onto 2D image will complicate subtle difference in X-ray transmission and objects at different depths will be superimposed on each other, the subtle difference in subject attenuation, diffraction and contrast may not be clearly visible or completely lost. Tomography with SR has superior visualization of subject contrast, together with depth localization, so it is useful for visualizing anatomical structures in the sample. In this study, the obtained SR cryo-micro CT images of human breast cancer tissue were comparable with standard histopathologic findings. The results suggest that tomography with SR has a great potential as a diagnostic tool and also its clinical application is feasible, especially in breast imaging.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P2-10-05.