Computed tomography laser mammography

This medical imaging technique uses laser energy in the near-infrared region of the spectrum to detect angiogenesis in the breast tissue.

[6][needs update] CTLM is a non-invasive practical system that uses near-infrared laser light propagation through the tissue to assess its optical properties.

[7] It is based on two basic principles: different tissue components have unique scattering and absorption characteristics for each wavelength and the malignant tumor growth requires neovascularization to grow beyond 2 mm in size.

[8][9][3] This neovascularization, which results in a greater volume of hemoglobin in a confined area, can be visualized using absorption measurements of laser light.

[11] At this wavelength, water, fat, and skin can only weakly absorb light, having little effect on data acquisition.

To solve this problem, CTLM system uses a large number of source and detector positions to take into account the diffusion approximation of light propagation in tissue, and to show the location of the increased vascularity in the breast.

This working array of CTLM device rotates 360 degrees around the breast and takes approximately 16,000 absorption measurements per slice.

It then descends to scan the next level after each rotation, creating a slice at each step of thickness 2 or 4 mm, depending on the size of the breast.

The forward model, an estimate of the average optical absorption, is computed for each slice, using the diffusion approximation of the transport equation.

It also corrects for geometric distortions due to bulk light-tissue interaction, and compensates for a spatially variant blurring effect that is typical of diffuse optical imaging.

Studies have shown that the shape and texture of angiogenesis in CTLM images are significant characteristics to differentiate malignancy or benign lesions.

A computer-aided diagnosis framework containing three main stages, volume of interest (VOI), feature extraction and classification, is used to enhance the performance of radiologist in the interpretation of CTLM images.

[citation needed] Dr. Eric Milne conducted a small localized study using CTLM as an adjunct to mammography; out of 122 cases, the number of biopsies required reduced from 89 to 47.

][needs update] CTLM has uses a near infrared laser of wavelength ~808 nm which is not impeded by the dense breast tissue.