Attempting to address the shortcomings of existing imaging and screening modalities, additional new technologies have been presented to the market during the past few years. Some - such as the BSGI and PEM - are already approved for marketing, while other - such as the CTLM - are still in clinical evaluation.
Breast-Specific Gamma Imaging (BSGI) is a molecular imaging procedure that captures the metabolic activity of breast lesions through radiotracer uptake (functional imaging). During a BSGI exam, the examinee is administered intravenously with a radioactive gamma emitting tracer agent which is absorbed by all cells in the body. Gamma rays emitted by the agent are detected by the BSGI image acquisition device and translated into a digital image of the breast. Since cancerous cells exhibit a more vigorous metabolic activity than normal breast tissue cells, they absorb a greater amount of the tracing agent, making them appear as irregularities.
Reported sensitivity and specificity of BSGI are higher than those of mammography, US and MRI. However, due to the invasiveness of the procedure and the administration of radioactive substance, BSGI seems unlikely to be widely adopted as an adjunct-to-mammography screening tool.
Positron Emission Mammography (PEM) is the application of high-resolution PET technology to an isolated immobilized breast, producing tomographic images of lesions with resolution down to 2 mm. This technology produces valuable clinical data on invasive and non-invasive disease across the continuum of care, from initial staging to ongoing post-surgical disease management.
Although the PEM exam bests mammography and MRI in both sensitivity and specificity, it also has its own disadvantages making it less likely to be widely adopted as a screening modality: Like BSGI, PEM requires the IV administration of a radioactive tracer agent (in significantly greater amounts); radiation exposure is twice as much as of mammography; the examinee isn't really spared with the inconvenience of mammography; and at $850K, the system is a relatively expensive imaging solution.
Computed Tomography Laser Mammography (CTLM) is a method of looking at the blood flow to the breast. The CTLM uses a monochromatic laser beam at a selected wavelength that is absorbed by hemoglobin, both oxygenated and deoxygenated. Since hemoglobin is only present in the blood, and because water and fat does not absorb light in the specific wavelength used (Near IR), the CTLM is able to create images of the distribution of blood within the breast and reveal abnormal vascularity such as the angiogenesis that characterizes malignant tumors.
The CTLM is not yet approved for marketing in the US and its developer, Imaging Diagnostic Systems Inc., has encountered significant difficulties in obtaining the Food and Drugs Administration (FDA) approval and accomplishing the clinical trials it initiated already in 2001. According to recent announcements by the company, it intends to accomplish the pivotal clinical trial and submit the Premarket Approval application by the end of 2008.
Clinical data collected so far regarding the CTLM does not suggest outstanding results for the technology: although a recent study states 85% sensitivity, the reported specificity was extremely low, at 61%. In extremely dense breast tissue, sensitivity was lower, 74%, and specificity 71%.