The potential role of positron emission mammography for detection of breast cancer. A phantom study

Abstract

Positron emission mammography (PEM) is a new, specialized imaging modality utilizing PET radiopharmaceuticals to detect breast cancer. The capabilities and limitations of PEM in detecting breast tumors were investigated with a series of phantom experiments. The PEM imager was mounted on a standard Lorad biopsy table (separated by 18 cm). In the initial phase of the investigation, basic scanner parameters (resolution, sensitivity, and scatter fraction) were measured. The effects of a number of breast imaging parameters (length of acquisition, breast thickness, and breast density) on detection of breast lesions were then explored utilizing special phantoms. Moderately compressed breasts were simulated with a block of gelatin containing amounts of FDG consistent with 370 MBq injections. Lesions were simulated with four hollow spheres (inner diameters=5 mm, 8 mm, 12 mm, and 15 mm) filled with amounts of FDG representative of uptake in malignant breast tumors (target-to-background concentration ratio=8.5:1). Resolution at the center of the imager was 3.9 mm, sensitivity was 0.059 kcps/kBq/ml and the Compton scatter fraction was approximately 12%. Objects as small as 8 mm in diameter could be detected after 30 s of data acquisition; 5 mm spheres were detectable after 300 s. Object detection capabilities were reduced with increasing breast thickness. In thin compressed breasts (2 cm) even the smallest sphere (5 mm in diameter) could be detected; increasing breast thickness increased the minimum detectable sphere diameter to 8 mm. Increased background activity caused by FDG uptake in metabolically active normal tissue more prevalent in radiodense breasts compared to "fatty" breasts was simulated and shown to reduce the minimum detectable lesion size to 12 mm for the densest breasts. These results demonstrate the potential of PEM for the detection of breast lesions. The addition of the system to a standard biopsy apparatus indicates its potential for use to guide some core biopsies of breast cancers.

Clear-PEM system counting rates: a Monte Carlo study

“…It brings together a favorable combination of high-density scintillator crystals coupled to compact photodetectors, arranged in a double readout scheme capable of providing depth-of-interaction (DOI) information [5]. Such characteristics could significantly improve breast imaging without sacrificing neither the sensitivity nor the spatial resolution of the system [6,7]. Experimental measurements has already demonstrated that Clear-PEM detector modules have adequate performance, achieving in particular a measurement of the photon interaction point along the crystal length with 2 mm FWHM resolution.…”

Instrumentation optimization for positron emission mammography

“…An increasing number of PET cameras optimized to image the breast have been proposed or constructed [1][2][3][4][5][6][7][8][9]. These cameras, commonly known as Positron Emission Mammography or PEM cameras, restrict the field of view to a single breast, and are expected to have higher performance and lower cost than a conventional PET camera.…”

Fundamental limits of positron emission mammography

“…The past several years have seen a number of designs for PET cameras optimized to image the breast [1][2][3][4][5][6][7][8][9], commonly known as Positron Emission Mammography or PEM cameras. The guiding principal behind PEM instrumentation is that a camera whose field of view is restricted to a single breast will have significantly higher performance and lower cost than a conventional PET camera.…”