Follow-up FDG PET in the evaluation of unexplained focal activity in the abdomen.
OBJECTIVE
This study assessed the value of a follow-up FDG PET scan when the initial PET demonstrated unexplained findings of focal FDG uptake in the abdomen.


METHODS
The records of 3634 patients with PET scans were retrospectively reviewed. Those patients who had follow-up PET scans after the initial PET scan showed unexplained FDG activity in the abdomen were further analyzed. The results from the second PET scan were compared with the follow-up data, which included the findings from other imaging modalities, clinical course, and biopsy or surgical pathology interpretations.


RESULTS
A total of 59 patients were included in the final analysis. The average time interval between the initial and the follow-up PET scans was 4.2 + 2.3 months. The follow-up PET provided a clear-cut diagnosis in 55 (93.2%) of these patients, whereas diagnoses in only 4 patients remained indeterminate. Follow-up PET scans were negative for abdominal malignancy in 38 patients. Thirty-five of these 38 patients with negative follow-up PET were proven to be without abdominal malignancy, with a negative predictive value of 92.1% (35 of 38). The follow-up PET was positive in 17 patients. Fifteen of these 17 patients with a positive follow-up PET scans were found to have malignancy in the abdomen with a positive predicative value of 88.2% (15 of 17). All 4 patients with indeterminate follow-up scans were proven not to have malignancy.


CONCLUSIONS
Follow-up FDG PET scan provides an effective means for diagnosing unexplained findings in the abdomen that were previously detected on initial PET scan.
Zhang
Yifan
Y
Department of Nuclear Medicine, Rui Jin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, PR China.
Xiu
Yan
Y
Zhuang
Hongming
H
Dadparvar
Simin
S
Yu
Jian Q
JQ
Dhurairaj
Thiruvenkatasamy
T
Alavi
Abass
A
D000005:Abdomen / Q000000981:diagnostic imaging*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D019788:Fluorodeoxyglucose F18; D005500:Follow-Up Studies; D006801:Humans; D033162:Incidental Findings; D008297:Male; D008875:Middle Aged; D019275:Radiopharmaceuticals; D012189:Retrospective Studies; D014055:Tomography, Emission-Computed
D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18