Comparative analysis of imaging sensitivity of positron emission mammography (PEM) and whole-body PET in relation to tumor size.

Objectives Positron emission mammography (PEM) consists of a dedicated PET scanner for breast imaging with a higher spatial resolution than whole-body PET (WBPET) scanners. This study compared the imaging sensitivity of PEM with WBPET in relation to tumor size.

Methods Fifty-four Japanese women younger than 50 years old with histologically confirmed breast lesions were retrospectively enrolled. PEM and WBPET were conducted on the same day. PEM and WBPET images were blindly evaluated and compared with histopathology. Tumors were classified into 3 groups based on size: Group 1, ≤1 cm; Group 2, 1-2 cm; and Group 3, >2 cm. The sensitivities of PEM and WBPET were compared in overall subjects and in each size group.

Results In visual analysis, the overall imaging sensitivity was 78.6% (33/42) for PEM, 47.6% (20/42) for WBPET. The overall sensitivity of PEM was significantly higher than that of WBPET (p<0.001). The differences in sensitivities between PEM and WBPET were larger in smaller tumors: Group 1 (66.7% vs 13.3%), Group 2 (63.4% vs 36.4%), and Group 3 (100.0% vs 87.5%). The sensitivity of PEM was significantly higher than that of WBPET in Group 1 (p=0.008); however no significant differences were seen in Group 2 (p=0.500) or Group 3 (p=0.250). Overall imaging specificity of PEM and WEBPET was 90.6% (60/66) and 93.9% (62/66), respectively.

Conclusions The imaging sensitivity of PEM was higher than that of WBPET in Japanese women younger than 50. PEM showed significant sensitivity in tumors <1 cm, which has been a weak point for WBPET.