Objectives: To identify the clinical relevance of incidentally detected lesions (IDLs) in the gastrointestinal tract (GIT) with 18F-FDG PET/CT and to assess the potential benefit of using semiquantitative PET measures to discern malignant from benign lesions.
Methods: Forty-one patients who underwent F-FDG PET/CT scans during the oncologic follow-up, revealing abnormal incidental 18F-FDG accumulations in the GIT were included in this retrospective analysis. Incidental PET/CT findings were correlated with endoscopic and histological findings. Semiquantitative PET values (SUVmax, SUVmean, SULpeak, and TLG) were evaluated by using a new graph-based method. Two sample t-test analysis has been performed to evaluate the differences of PET parameters between precancerous or cancerous lesions and inflammatory disease.
Results: Nine of the 41 patients had an IDL of the GIT on F-FDG PET/CT (detection rate 22%). Endoscopic examination and biopsy have confirmed the presence of precancerous or cancerous lesions as follow: colonic adenoma with high-grade dysplasia (N = 2), colonic adenoma with low-grade dysplasia (N =3), colonic metastatic lesion from primary breast cancer (N =1), gastric carcinoma (N=3). Precancerous or cancerous lesions showed a higher SUVmax, SUVmean, SULpeak, and TLG with a mean value of 10.6 (range, 5.3- 16.7), 6.2 (range, 2.1-10.6), 5.2 (2.7-11), and 66.6 (range, 7.4-164), than patients with inflammatory and endoscopically negative lesions. Two sample t-test analysis showed that SUVmean (P = 0.03), SULpeak (P = 0.05) were statistically different between the two subgroups.
Conclusion: The use of new semiquantitative PET parameters may increase the diagnostic yield of FDG PET in the case of abnormal incidental F-FDG accumulations.