The role of F-18 positron emission tomography/computed tomography in evaluation of extranodal lymphoma

Aim and objectives: To assess the added value of hybrid FDG PET/CT in evaluation of extranodal lymphoma. Methodology: In this study, PET/CT was done for 50 patients with lymphoma; (36 NHL and 14 HD), to evaluate its value over CT alone in detecting extranodal extension. Results: The commonest extranodal sites affected by lymphomatous infiltration are in the following order: lung, bone, bone marrow, spleen, liver, GIT, head and neck, pleura, cutaneous tissue, peritoneum, brain, muscle and pancreas. Regarding the final outcome of the reviewed 77 extranodal lesions: depending on the criteria accepted as standard reference including histopathological results, clinical or radiological follow up, CT defined 66 (85.7%) studies as positive and 11 (14.3%) as negative. While PET/CT defined 71 (92.2%) studies as positive and 6 (7.8%) as negative. Most of the disagreement between both modalities (PET/CT and CT) could be detected among splenic, bone and bone marrow lesions. PET/CT was more sensitive and specific than CT alone in detecting extranodal lesions with sensitivity 97.22% and specificity 80%. Conclusion: PET/CT is superior over CT alone in detecting extranodal extension especially among splenic, bone and bone marrow lesions.