(18)F-DG PET/CT in detection of recurrence and metastasis of colorectal cancer

Abstract

Aim: To evaluate the value of (18)F-DG PET/CT in detecting recurrence and/or metastasis of colorectal cancer (CRC).

Methods: Combined visual analysis with semiquantitative analysis, the (18)F-DG PET/CT whole-body imaging results and the corresponding clinical data of 68 postoperative CRC patients including 48 male and 20 female with average age of 58.1 were analyzed retrospectively.

Results: Recurrence and/or metastasis were confirmed in 56 patients in the clinical follow-up after the PET/CT imaging. The sensitivity of PET/CT diagnosis of CRC recurrence and/or metastasis was 94.6%, and the specificity was 83.3%. The positive predictive value (PPV) was 96.4% and the negative predictive value (NPV) was 76.9%. PET/CT imaging detected one or more occult malignant lesions in 8 cases where abdominal/pelvic CT and/or ultrasonography showed negative findings, and also detected more lesions than CT or ultrasonography did in 30.4% (17/56) cases. Recurrence and/or metastasis was detected in 91.7% (22/24) cases with elevated serum CEA levels by (18)F-DG PET/CT imaging.

Conclusion: (18)F-DG PET/CT could detect the recurrence and/or metastasis of CRC with high sensitivity and specificity.

Figure 1

PET/CT imaging showing local recurrent rectal carcinoma in a 49-year-old female postoperative rectal cancer patient. CT scan did not find definite recurrence signs. PET imaging detected hyper-intensive radioactivity by the left side of uterus. The SUV_max was 7.5 and the T/N was 9.4. Combined PET/CT imaging indicated elevated ¹⁸F-DG uptake of the anastomosis. The reoperation confirmed a recurrent tubular adenocarcinoma of the rectum.

Figure 2

PET/CT imaging showing isolated hepatic metastasis in a 69-year-old female postoperative sigmoid carcinoma patient. CT scan did not find definite recurrence signs. PET imaging detected localized hepatic subcapsular hyper-intensive radioactivity. Local resection of liver lobe was performed in the reoperation, and metastatic adenocarcinoma was confirmed.

Figure 3

PET/CT imaging showing hepatic metastasis after local therapy in a 60-year-old male postoperative colon cancer patient. ¹²⁵I seeds brachytherapy was performed in the metastatic lesion of the liver, causing necrosis and ¹⁸F-DG uptake decrease of the lesion. However, additional localized hepatic subcapsular hyper-intensive radioactivity was detected, indicating that new liver metastasis had occurred.