Park et al. needed. DISCUSSION About half of all cases of recurrent uterine cervical can- cer are confined to the pelvic cavity, but some cases show metastatic lesions in the lymph nodes, lung, bone, and liver (9). Halpin et al. (1) reported that where there is recur- rence, 60 per cent of cases are diagnosed within two years, and 82 per cent within four years. Eighty percent of pa- tients in whom there was recurrence died within one year, and ninety percent within two years. The treatment of recurrent uterine cervical cancer differs according to the extent of the recurrent lesion. If this is confined to the pelvic cavity, pelvic exenteration is the treatment of choice. On the other hand, if it recurs beyond the pelvic cavity, radiation therapy or chemotherapy is preferred. The detection and exact localization of a recur- rent lesion are therefore very important (10). Clinically, patients with recurrence complain of back pain, sciatic pain, and edema of the lower leg, but some show no symptoms or signs of recurrent cervical cancer (1, 2). Radiologic imaging studies such as IVU, barium enema, lymphangiography, and US are used to detect recurrent u- terine cervical cancer, but the findings are indirect (2). In cases of recurrent cervical cancer, CT scanning demon- strates a pelvic mass or enlarged pelvic and para-aortic lymph nodes (2). The extent of a tumor, and lymphade- nopathy and hydronephrosis, can be easily detected on CT (2). CT scanning is also helpful in determining the radiation portal, the site for biopsy, and the effect of treatment. Consequently, the modality has been used as a gold stan- dard in the diagnosis of recurrent uterine cervical cancer. With CT scanning, however it may be difficult to differen- tiate recurrence from postoperative and postradiation fi- brosis, and to detect normal-sized metastatic lymph nodes (2, 3). On MR images, a recurrent lesion shows increased signal intensity on T2-weighted images, but reports of its specificity and sensitivity have varied. In addition, MR can- not distinguish necrosis, edema, hemorrhage and inflam- mation from recurrence (4 7). PET with FDG, which makes use of increased glycolysis levels in tumor cells, is a noninvasive diagnostic method used in functional imaging of the tumor, and has been used to detect primary tumors and recurrence, to determine the efficacy of therapy, for staging, and to detect the extent of a tumor (11 25). Ogunbiyi et al. (20) compared PET with CT in the detection of recurrent or metastatic colon and rectal cancer. They reported that PET accurately detected met-astatic lesions as well as local recurrences, and was es- pecially effective in differentiating between recurrence and 54 postoperative fibrosis. Anzai et al. (12) compared PET with CT and MR in recurrent head and neck cancer after surgery or radiation therapy, and reported that local hematoma, abscess, fistula, and reconstruction flap could not be clearly differentiated from local recurrence. They al- so reported that sensitivity and specificity were 88% and 100% with PET, but 25% and 75% with CT and MR, re- spectively. Hudgins et al. (26) reported that in head and neck cancer, MR could not easily distinguish between postradiation fibrosis and recurrence. McGuirt et al. (18) also reported that PET was superior to CT in terms of sen- sitivity and specificity, and that if PET revealed no areas of high metabolism, pathologic examination could be de- layed. PET is superior to CT in detecting small metastatic lymph nodes, especially in patients in whom the fat content of the retroperitoneum is low. Thus, PET is effective in distin- guishing metastatic lymph nodes from testicular cancer, lymphoma, and rectal and cervical cancer, which prefer to metastasize to retroperitoneal lymph nodes. PET can also differentiate recurrence from scar tissue, irrespective of anatomical alteration and surgical clip (27). With CT, we also experienced difficulty in differentiating recurrence from postoperative and postradiation fibrosis and in de- tecting small lymph nodes. PET can, in addition, be used to obtain whole body images and detect recurrence that was not clinically suspected. A disadvantage of PET is its high cost; another is that it does not easily determine anatomical location and tumor extent. Using PET, we were unable to decide the exact location of a recurrent mass and the ex- tent of invasion of an adjacent organ. Eventually, there- fore, in order to decide the treatment plans of patients in whom recurrence was detected, CT was required. In conclusion, PET is a reliable diagnostic screening modality. It can detect small lymph nodes, distinguish be- tween recurrence and fibrosis, and can be used for whole- body scanning. Tumor localization is not one of its stren- gths, however, and in order to determine a treatment plan, CT scanning is therefore necessary. References 1. Halpin TF, Frick HC. Munnell EW. Critical points of failure in the therapy of cancer of the cervix: a reappraisal. Am J Obstet Gynecol 1972;114:755-764 2. Walsh JW, Amendola MA, Hall DJ, Tisnado J, Goplerud DR. Recurrent carcinoma of the cervix: CT diagnosis. AJR 1981;136:117-122 3. Cunningham JJ, Fuks ZY, Castellino RA. Radiographic manifes- tations of carcinoma of the cervix and complications of its treat- ment. Radiol Clin North Am 1974;12:93-108 4. Weber TM, Sostman HD, Spritzer CE, et al. Cervical carcinoma: determination of recurrent tumor extent versus radiation changes with MR imaging. Radiology 1995;194:135-139 Korean J Radiol 1(1), March 2000