Evaluation of image quality at the detector’s edge of dedicated breast positron emission tomography

Abstract

Background Using phantoms and clinical studies in prone hanging breast imaging, we assessed the image quality of a commercially available dedicated breast PET (dbPET) at the detector’s edge, where mammary glands near the chest wall are located. These are compared to supine PET/CT breast images of the same clinical subjects. Methods A breast phantom with four spheres (16-, 10-, 7.5-, and 5-mm diameter) was filled with 18F-fluorodeoxyglucose solution (sphere-to-background activity concentration ratio, 8:1). The spheres occupied five different positions from the top edge to the centre of the detector and were scanned for 5 min in each position. Reconstructed images were visually evaluated, and the contrast-to-noise ratio (CNR), contrast recovery coefficient (CRC) for all spheres, and coefficient of variation of the background (CVB) were calculated. Subsequently, clinical images obtained with standard supine PET/CT and prone dbPET were retrospectively analysed. Tumour-to-background ratios (TBRs) between breast cancer near the chest wall (close to the detector’s edge; peripheral group) and at other locations (non-peripheral group) were compared. The TBR of each lesion was compared between dbPET and PET/CT. Results Closer to the detector’s edge, the CNR and CRC of all spheres decreased while the CVB increased in the phantom study. The disadvantages of this placement were visually confirmed. Regarding clinical images, TBR of dbPET was significantly higher than that of PET/CT in both the peripheral (12.38 ± 6.41 vs 6.73 ± 3.5, p = 0.0006) and non-peripheral (12.44 ± 5.94 vs 7.71 ± 7.1, p = 0.0183) groups. There was no significant difference in TBR of dbPET between the peripheral and non-peripheral groups. Conclusion The phantom study revealed poorer image quality at < 2-cm distance from the detector’s edge than at other more central parts. In clinical studies, however, the visibility of breast lesions with dbPET was the same regardless of the lesion position, and it was higher than that in PET/CT. dbPET has a great potential for detecting breast lesions near the chest wall if they are at least 2 cm from the edge of the FOV, even in young women with small breasts.

Exploration of tumor size measurement methods in preoperative breast cancer assessment using whole-body silicon photomultiplier PET: feasibility and first results

“…We assume that it is possible to diagnose the spread of cancer within the breast by imaging in the prone position using WB SiPM PET/CT. Breast PET has the disadvantage of having a blind area in the mammary glands near the chest wall because the detector cannot fully cover the anterior chest wall [12,13]. However, WB SiPM PET/CT does not have this blind area near the chest wall and has the advantage of being able to simultaneously evaluate uptake in the regional lymph nodes.…”

Tumor size of preoperative breast cancer assessment by whole-body silicon photomultiplier PET: feasibility and first results

“…We assume that it is possible to diagnose the spread of cancer within the breast by imaging in the prone position using WB SiPM PET/CT. Breast PET has the disadvantage of having a blind area in the mammary glands near the chest wall because the detector cannot fully cover the anterior chest wall [11,12]. However, WB SiPM PET/CT does not have this blind area near the chest wall and has the advantage of being able to simultaneously evaluate uptake in the regional lymph nodes.…”

Organ-Specific Positron Emission Tomography Scanners for Breast Imaging: Comparison between the Performances of Prior and Novel Models

“…The two positions in which the spheres were placed were the center and the periphery, i.e., 2 cm below the top edge, of the axial FOV of each detector. This was because although the dbPET image quality has been reported to degrade at <2 cm from the edges of the ring-shaped detector [ 17 ], the image quality of both scanners should be comparatively evaluated, since BC near the chest wall is often located in this region.…”