title: Clinical significance of incidental finding of focal activity in the breast at 18F-FDG PET/CT.
abstract: OBJECTIVE
  The purpose of this study was to determine the clinical significance of the incidental finding of hypermetabolic foci in the breast at (18)F-FDG PET/CT in patients with malignant disease other than breast cancer or during a screening examination.
  
  
  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, maximum standard uptake value (SUV(max)) 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 SUV(max) less than 2 (24.2%) and the group with SUV(max) 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 difference 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.
  
  
  CONCLUSIONS
  Incidental hypermetabolic foci in the breast may represent malignancy in as many as 37.5% of cases. The SUV(max) and sonographic findings can be useful for differentiating benign from malignant lesions.
authors.affiliation: Department of Radiology, Seoul St. Mary's Hospital, College of Medicine, The Catholic University of Korea, 505 Banpo-Dong, Seocho-Ku, Seoul 137-040, Korea.
authors.forename: Bong Joo
authors.initials: BJ
authors.lastname: Kang
authors.forename: Ji Hye
authors.initials: JH
authors.lastname: Lee
authors.forename: Ie Ryung
authors.initials: IeR
authors.lastname: Yoo
authors.forename: Sung Hun
authors.initials: SH
authors.lastname: Kim
authors.forename: Jae Jeong
authors.initials: JJ
authors.lastname: Choi
authors.forename: Seung Hee
authors.initials: SH
authors.lastname: Jeong
authors.forename: Hyeon Woo
authors.initials: HW
authors.lastname: Yim
mesh_terms: D000368:Aged; D001943:Breast Neoplasms / Q000000981:diagnostic imaging*; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D033162:Incidental Findings; D008875:Middle Aged; D009367:Neoplasm Staging; D009369:Neoplasms / Q000000981:diagnostic imaging*; D049268:Positron-Emission Tomography / Q000379:methods*; D019275:Radiopharmaceuticals; D012044:Regression Analysis; D012189:Retrospective Studies; D018709:Statistics, Nonparametric; D014057:Tomography, X-Ray Computed / Q000379:methods*; D016217:Ultrasonography, Mammary
chemical_list: D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18