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.
Forty-one patients who underwent 18F-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.
Nine of the 41 patients had an IDL of the GIT on 18F-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.
The use of new semiquantitative PET parameters may increase the diagnostic yield of FDG PET in the case of abnormal incidental 18F-FDG accumulations.