Detection of recurrence in patients with rectal cancer: PET/CT after abdominoperineal or anterior resection.
OBJECTIVE
To assess diagnostic accuracy of combined positron emission tomography (PET) and computed tomography (CT) in detection of pelvic recurrence in patients with rectal cancer who underwent abdominoperineal or anterior resection.


METHODS
Sixty-two patients were enrolled; 37 were men, and 25 were women. Seventeen patients underwent abdominoperineal resection and 45 underwent anterior resection with an anastomosis in the pelvic region before referral for PET/CT. Pelvic sites of fluorine 18 ((18)F) fluorodeoxyglucose (FDG) uptake were rated separately on PET and PET/CT images as benign or malignant on the basis of shape, location, and intensity of (18)F FDG uptake (1-2 = benign and/or physiologic, 3 = equivocal, 4-5 = malignant). Two readers interpreted images in consensus. Altered pelvic anatomy and presence of presacral abnormalities were assessed with CT. Pelvic recurrence was confirmed with histologic analysis or clinical and imaging follow-up. Sensitivity, specificity, positive and negative predictive values, and accuracy of PET and PET/CT in the detection of pelvic recurrence were compared with lesion- and patient-based analyses by using the chi(2) test. Clinical relevance of PET/CT assessment was determined.


RESULTS
Of 81 pelvic sites with increased (18)F FDG uptake, 44 were malignant. Sensitivity, specificity, positive predictive value, negative predictive value, and accuracy for differentiating malignant from benign (18)F FDG uptake in the pelvis were 98%, 96%, 90%, 97%, and 93% for PET/CT and 82%, 65%, 73%, 75%, and 74% for PET, respectively. The most common cause for false-positive interpretation of PET findings was physiologic (18)F FDG uptake in displaced pelvic organs. Presacral CT abnormalities were present in 30 (48%) of 62 patients, and seven (23%) abnormalities were malignant. PET/CT was used to distinguish benign and malignant presacral abnormalities with a sensitivity, specificity, positive predictive value, and negative predictive value of 100%, 96%, 88%, and 100%, respectively. PET/CT findings were clinically relevant in 29 (47%) of 62 patients.


CONCLUSIONS
PET/CT is an accurate technique in the detection of pelvic recurrence after surgical removal of rectal cancer.
Department of Nuclear Medicine, Tel Aviv Sourasky Medical Center, 6 Weizman St, Tel Aviv 64239, Israel. evensap@tasmc.health.gov.il
Einat
E
Even-Sapir
Yoav
Y
Parag
Hedva
H
Lerman
Mordechai
M
Gutman
Charles
C
Levine
Micha
M
Rabau
Arie
A
Figer
Ur
U
Metser
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000000981:diagnostic imaging*; D010386:Pelvic Neoplasms / Q000601:surgery; D012004:Rectal Neoplasms / Q000000981:diagnostic imaging*; D012189:Retrospective Studies; D014055:Tomography, Emission-Computed; D014057:Tomography, X-Ray Computed