Detection of recurrent colorectal cancer by 18F-FDG PET/CT comparison with contrast enhanced CT scan.

Objective : To evaluate diagnostic performance of 18F-FDG PET/CT in assessment of recurrence colorectal cancer after treatment in Siriraj Hospital. Material and Method : The authors retrospectively studied 48 treated colorectal cancer patients with suspected recurrence who underwent 18F-FDG PET/CT and contrast-enhanced CT (CECT). Clinical information, image follow-up for at least one year, and pathological reports of the patients were reviewed for gold standard. Results : Recurrent or metastatic disease was found in 36 of 48 patients. Calculated sensitivity, specificity, and accuracy of 18F-FDG PET/CT were 94.4%, 66.7%, and 87.5%. 18F-FDG PET/CT can reduce false positive results of CECT in six patients, thus specificity of 18F-FDG PET/CT was statistically significantly better than that of CECT. Using lesion-based analysis with 65 recurrent sites and 26 non-recurrent lesion, 18F-FDG PET/CT showed better sensitivity 87.7%, specificity 61.5%, and accuracy 80.2 than CECT without statistical significance. Conclusion : 18F-FDG PET/CT overall showed higher sensitivity, specificity, and accuracy than CECT. Keywords : 18F-FDG PET/CT, Recurrent colon cancer