@article {Kumar1796, author = {Rakesh Kumar and Yan Xiu and Scott Potenta and Ayse Mavi and Hongming Zhuang and Jian Q. Yu and Thiruvekatasamy Dhurairaj and Simin Dadparvar and Abass Alavi}, title = {18F-FDG PET for Evaluation of the Treatment Response in Patients with Gastrointestinal Tract Lymphomas }, volume = {45}, number = {11}, pages = {1796--1803}, year = {2004}, publisher = {Society of Nuclear Medicine}, abstract = {18F-FDG PET is highly sensitive and specific for evaluation of the treatment response of nodal and extranodal diseases in patients with malignant lymphomas. However, no data are available in the literature with regard to 18F-FDG PET for evaluation of the treatment response in patients with lymphomas with gastrointestinal tract (GIT) involvement. This study was undertaken to investigate the usefulness of 18F-FDG PET in monitoring the response to the treatment of lymphomas in this setting. Methods: We retrospectively analyzed 19 patients with different types of lymphomas (10 diffuse large B-cell lymphomas, 4 follicular lymphomas, 3 mantle cell lymphomas, and 2 Hodgkin{\textquoteright}s disease) involving GIT. Among 19 patients, 4 had gastric involvement, 13 had small bowel involvement, and 2 had small bowel plus colon involvement by lymphomas. All patients underwent 18F-FDG PET before and after the completion of therapy. The results of 18F-FDG PET were compared with the results of CT and clinical outcome; the presence of relapse was determined on the basis of positive biopsy results or clinical follow-up data. Results: Of the 19 posttreatment PET scans, 13 showed no pathologic 18F-FDG uptake, whereas 6 showed persistent 18F-FDG uptake. Among the 13 patients who had negative PET scans, only 1 patient (7.7\%) relapsed, whereas all 6 patients (100\%) who had persistent abnormal 18F-FDG uptake on posttherapy PET scans relapsed. Posttreatment CT scans were negative for 10 patients but showed persistent disease in the remaining 9 patients. Among the 10 patients who had negative CT scans, 9 remained in remission and 1 (10\%) relapsed. Of the 9 patients who showed persistent disease, 6 (67\%) relapsed and 3 (33\%) remained in remission after the mean follow-up of 20 mo. The sensitivity, specificity, positive and negative predictive values, and accuracy of posttherapy 18F-FDG PET were 86\%, 100\%, 100\%, 92\%, and 95\%, respectively. The corresponding values for CT were 67\%, 75\%, 75\%, 90\%, and 79\%, respectively. Patients with positive 18F-FDG PET results had statistically significantly lower disease-free survival (DFS) (0\%) than did those with positive CT results (33\%) (P = 0.04). There was no statistically significant difference in DFS between patients with negative 18F-FDG PET results and patients with negative CT results. Conclusion: A positive 18F-FDG PET scan after the completion of chemotherapy in patients with lymphomas with GIT involvement is a strong predictor of relapse. 18F-FDG PET has higher diagnostic accuracy than CT in the detection of residual disease after therapy. Despite the mild physiologic 18F-FDG uptake in the GIT, 18F-FDG PET has potential value in monitoring the response to treatment in patients with GIT lymphomas, particularly when pretreatment PET results are positive.}, issn = {0161-5505}, URL = {https://jnm.snmjournals.org/content/45/11/1796}, eprint = {https://jnm.snmjournals.org/content/45/11/1796.full.pdf}, journal = {Journal of Nuclear Medicine} }