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Background: Breast lesions closer than 2 cm to the chest wall are difficult to position in the field of view of dedicated breast PET (db-PET) systems. This inability to detect such lesions is a significant limitation of these systems. The primary objective of this study was to determine if modifications to the design of the imaging table and detector used for a db-PET system would enable improved visualization of breast tissue close to the chest wall. All studies were performed on a commercially available db-PET system (Mammi-PET). A central square section of the imaging table, containing the standard 180-mm circular aperture, was modified such that it could be removed and replaced by thinner sections with a larger aperture. Additional changes were made to the cover plate of the detector array and the patient mattress. A total of 60 patients were studied. After administration of F-18 FDG, 30 patients were imaged with a 220-mm-diameter aperture and the standard aperture, and 30 patients with a 200-mm aperture and the standard aperture. On all scans, the length of breast tissue in the field of view was measured as the greatest extent of tissue from the nipple back to the posterior edge of the breast. Image quality and patient comfort were recorded. Results: Averaged over both breasts, relative to the standard aperture, the increase in breast length was 12.5 + 7.7 mm with the 220-mm aperture, and 12.3 + 6.5 mm with the 200-mm aperture ( p < 0.05 for both apertures). In ~ 5% of cases, the larger apertures resulted in some degradation in image quality due to closer proximity to cardiac/hepatic activity. In 10-20% of cases, movement of the breast tissue was observed as the detector ring was moved to scan the anterior region of the breast. The patient survey indicated no significant difference in the comfort level between the standard aperture and either of the prototype apertures. Conclusions: Modifications to the image table and system resulted in a significant gain in the volume of breast tissue that could be imaged on the db-PET system and should allow better visualization of lesions close to the chest wall. [ABSTRACT FROM AUTHOR]

Background: Molecular breast imaging (MBI) performed with Tc sestamibi has been shown to be a valuable technique for the detection of breast cancer. Alternative radiotracers such as Tc maraciclatide may offer improved uptake in breast lesions. The purpose of this study was to compare relative performance of Tc sestamibi and Tc maraciclatide in patients with suspected breast cancer, using a high-resolution dedicated gamma camera for MBI. Women with breast lesions suspicious for malignancy were recruited to undergo two MBI examinations-one with Tc sestamibi and one with Tc maraciclatide. A radiologist interpreted MBI studies in a randomized, blinded fashion to assign an assessment score (1-5) and measured lesion size. Lesion-to-background (L/B) ratio was measured with region-of-interest analysis. Results: Among 39 analyzable patients, 21 malignant tumors were identified in 21 patients. Eighteen of 21 tumors (86%) were seen on Tc sestamibi MBI and 19 of 21 (90%) were seen on Tc maraciclatide MBI ( p = 1). Tumor extent measured with both radiopharmaceuticals correlated strongly with pathologic size (Tc sestamibi, r = 0.84; Tc maraciclatide, r = 0.81). The L/B ratio in detected breast cancers was similar for the two radiopharmaceuticals: 1.55 ± 0.36 (mean ± S.D.) for Tc sestamibi and 1.62 ± 0.37 (mean ± S.D.) for Tc maraciclatide ( p = 0.53). No correlation was found between the L/B ratio and molecular subtype for Tc sestamibi ( r = 0.12, p = 0.63) or Tc maraciclatide ( r = −0.12, p = 0.64). Of 20 benign lesions, 10 (50%) were seen on Tc sestamibi and 9 of 20 (45%) were seen on Tc maraciclatide images ( p = 0.1). The average L/B ratio for benign lesions was 1.34 ±0.40 (mean ±S.D.) for Tc sestamibi and 1.41 ±0.52 (mean ±S.D.) for Tc maraciclatide ( p = 0.75). Overall diagnostic performance was similar for both radiopharmaceuticals. AUC from ROC analysis was 0.83 for Tc sestamibi and 0.87 for Tc maraciclatide ( p = 0.64). Conclusions: Tc maraciclatide offered comparable lesion uptake to Tc sestamibi, in both malignant and benign lesions. There was good correlation between lesion extent and uptake measured from both radiopharmaceuticals. Tc maraciclatide offered a marginal (but not significant) improvement in sensitivity over Tc sestamibi. Our findings did not support an association between the uptake of either radiopharmaceutical and tumor molecular subtype. Trial registration: ClinicalTrials.gov, [ABSTRACT FROM AUTHOR]