AJR:197,August 2011
Bong Joo Kang, Ji Hye Lee, le Ryung Yoo, Sung Hun Kim, Jae Jeong Choi, Seung Hee Jeong, Hyeon Woo Yim
OBJECTIVE. The purpose of this study was to determine the clinical significance of the incidental finding of hypermetabolic foci in the breast at 18F-FDG PET/CT in patients with malignant disease other than breast cancer or during a screening examination.
MATERIALS AND METHODS. The files of 13,897 women who underwent FDG PET/ CT from November 2004 to October 2009 were retrospectively reviewed. Forty-eight patients with incidental breast uptake had undergone either tissue confirmation or clinical follow-up with additional sonographic imaging. The following four variables were evaluated: age, maxi¬mum standard uptake value (SUVmax) of breast uptake at FDG PET, findings in the CT portion of PET/CT, and sonographic findings. Malignancy rates were calculated for each variable.
RESULTS. Malignancy was diagnosed in 18 (37.5%) patients and a benign condition in 30 (62.5%) patients. Statistically significant differences in malignancy rate were found between the groups with SUVmax less than 2 (24.2%) and the group with SUVmax of 2 or greater (66.7%) and between the group with lesions in a BI-RADS ultrasound category lower than 4 (10.7%) and the group with lesions in category 4 or higher (75.0%) (p < 0.05). There was no significant dif-ference in malignancy rates between the groups younger than 45 years (11.1%) and 45 years and older (53.3%) or between the group with lesions in a BI-RADS category lower than 4 (30.2%) and that with lesions in category 4 or higher (100%) on the CT portion of PET/CT.
CONCLUSION. Incidental hypermetabolic foci in the breast may represent malignancy in as many as 37.5% of cases. The SUVmax and sonographic findings can be useful for differentiating benign from malignant lesions.