Diagnostic accuracy of two dedicated PET scanners for breast imaging

Objectives The purpose of this study was to investigate the diagnostic performance of two newly-developed dedicated breast PET (dbPET) scanners in patients with known or suspected breast cancer.

Methods There were two types of dbPET scanners, the O-shaped (dbPET-O) and the C-shaped (dbPET-C). 144 female patients underwent a conventional whole body PET/CT scan, followed by breast scanning using either one or both scanners for five minutes for each side. A total of 142 lesions (136 malignant, 4 benign, and 2 unclassified) were evaluated with the dbPET-O, and 143 lesions (136 malignant, 5 benign, and 2 unclassified) were evaluated with the dbPET-C. Based on the final diagnosis obtained by biopsy and/or surgery, diagnostic performance of these scanners was assessed.

Results The maximal diameter of lesions ranged from 2 to 116 mm with an average of 24 mm. With the dbPET-O, 110 of 136 malignant lesions were detected, 12 lesions were not detected, and the remaining 14 lesions were outside of the field of view. With the dbPET-C, 107 of 136 malignant lesions were detected, 14 lesions were not detected, and the remaining 15 lesions were outside the field of view. Excluding lesions outside the field of view, the sensitivities of dbPET-O and dbPET-C were 94% (109/116) and 92% (108/118), respectively, in patient-basis, and 90% (110/122) and 88% (107/121), respectively, in lesion-basis. For lesions of ductal carcinoma in situ, size of which was ranging from 2 to 48 mm, the lesion-based sensitivities of these scanners were 71% (5/7) and 57% (4/7), respectively, excluding three lesions outside of the field of view. The breast-based specificities of dbPET-O and dbPET-C were 99% (104/105) and 98% (107/109), respectively. For two unclassified lesions, the adenomatous ductal hyperplasia was not depicted, while the flat epithelial atypia was described in both scanners.

Conclusions Both dbPET scanners were clinically feasible and yielded reasonably high sensitivity and specificity; however, some lesions located in the chest wall were tended to be missed