New PEM/PET system may be able to detect small breast tumors

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The positron emission mammography (PEM)/PET system may be an effective system for the detection and diagnosis of breast cancer, according to a study to be published in the Feb. 7 issue of Physics in Medicine and Biology.

Scientists at the Department of Energy's Thomas Jefferson National Accelerator Facility in Newport News, Va., West Virginia University (WVU) School of Medicine in Morgantown, W.Va., and the University of Maryland School of Medicine in Baltimore, designed and constructed the system.

Raymond R. Raylman, a professor of radiology and vice chair of radiology research at WVU, and colleagues from the above facilities, used PEM/PET system to detect and guide the biopsy of suspicious breast lesions. The scientists said they acquired PET images to detect suspicious focal uptake of the radiotracer and guide biopsy of the area, and limited-angle PEM images could then be used to verify the biopsy needle position prior to tissue sampling.

They performed image reconstruction with a 3D ordered set expectation maximization algorithm parallelized to run on a multi-processor computer system. The authors wrote that the reconstructed field of view (FOV) is 15x15x15 cm3.

The initial phantom-based testing of the device was focused upon its PET imaging capabilities, and specifically, spatial resolution and detection sensitivity were assessed, according to the researchers.

The authors found that the measurements yielded a spatial resolution at the center of the FOV of 2.01mm (radial), 2.04mm (tangential) and 1.84mm (axial). At a radius of 7 cm from the center of the scanner, the results were 2.11mm (radial), 2.16mm (tangential) and 1.87mm (axial). They also found that the maximum system detection sensitivity of the scanner is 488.9 kcps µCi-1 ml-1 (6.88 percent).

The scientists concluded that the system is especially useful in imaging tumors in women who have indeterminate mammograms because of dense or fibroglandular breasts.

The Jefferson Lab Radiation Detector and Medical Imaging Group, with a group member now affiliated with the University of Maryland School of Medicine, developed the detector heads with the on-board electronics, the data acquisition readout and the image reconstruction software. The imaging device's gantry and the motion-control software were developed by WVU researchers.

In the future, the team will make improvements in the detector systems and image reconstruction software and the addition of components for taking x-ray CT scans. The team has planned initial clinical trials once system testing is complete.