Abstract 4299: Comparison of high-resolution 3D X-ray microCT and tomosynthesis imaging: A breast phantom study
Authors: Singh Jolene M. , Bui Anthony H. , Michaelson James S. 
Published: May 2015

We have demonstrated the feasibility of imaging a mammographic accreditation phantom using high-resolution 3D X-ray microCT as an alternative to tomosynthesis. While both X-ray microCT and tomosynthesis produce high-resolution 3D images, tomosynthesis requires compression of the specimen and yields asymmetrical voxels, resulting in high spatial resolution along two axes and more limited resolution along the third axis. MicroCT imaging, however, does not require compression and provides uniform, high resolution in all directions. The limited angular range of tomosynthesis is advantageous for pre-operative screening tasks, while the increased spatial and full angular range of microCT has been increasingly applied to the assessment of surgically excised breast tissue during breast conserving surgery. Rapid and accurate assessment of excised tissues is desirable to minimize risk of recurrence, which is highest in the first two years after surgery.

We employed a 35-80 kV, 7.6-15W scan protocol in X-ray microCT to image the breast phantom. We also tested the ability to detect the phantom target features (2.00-0.16 mm) in long (25 minute) and short (5-6 minute) scans. The phantom was designed to simulate the X-ray attenuation of a slab of compressed human breast consisting of glandular and adipose tissue. Both X-ray microCT and tomosynthesis were able to capture the smallest features (0.16 mm) of the phantom. Both long- and short-duration microCT scans enabled detection of the smallest (0.16mm) features of the phantom. The results obtained here suggest that (1) microCT could be used, as an alternative to tomosynthesis, to identify and localize features on the order of 100-200 microns in ex vivo tumor specimens and (2) microCT could be used to detect features of this size on an intra-operative basis (in 5-6 minute scans).

This study shows the feasibility of using microCT for intra-operative 3D examination of surgical specimens, an application which could aid clinical decision-making in assessment of excision margins. Additionally, if high-resolution 3D imaging techniques can distinguish between features of tumor and non-tumor areas of tissues, as is suggested by these results, then these imaging modalities could hold promise for identification of biomarkers and elucidation of the gross anatomy of breast tumor types, such as ductal carcinoma in situ. There is not yet an accepted phantom for testing the detection limits of 3D high-resolution X-ray imaging. The phantom used here is a validated tool for calibration of mammography instruments, but it seems that digital X-ray imaging technologies, such as microCT, can quite easily capture the features of this phantom. Therefore, while microCT performed as well as tomosynthesis in detection of features in this breast phantom study, there is a need for the development and validation of new phantoms to assess the ability of tomosynthesis and microCT to resolve features in the &lt;100 micron range.

Citation Format: Jolene M. Singh, Anthony H. Bui, James S. Michaelson. Comparison of high-resolution 3D X-ray microCT and tomosynthesis imaging: A breast phantom study. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 4299. doi:10.1158/1538-7445.AM2014-4299