Diagnostic role of 18F-FDG PET in gastric MALT lymphoma

The aim of the study was to evaluate the usefulness of 18F-FDG-PET in patients with gastric lymphoma, in particular those affected by mucosa-associated lymphoid tissue (MALT) type and aggressive gastric non-Hodgkin's lymphoma (NHL). The study group consists of 15 patients with a previous diagnosis of gastric NHL referred to our PET centres in Bologna Hospital and Rovigo Hospital, Italy, in the period 2003-2004. In 9/15 patients the subsequent histological evaluation was consistent with a gastric MALT lymphoma, while aggressive gastric NHL was diagnosed in the other 6/15. PET scan was carried out in patients with known active disease in order to stage or re-stage disease prior to treatment or in patients in complete clinical remission to monitor disease during follow up. Patients were considered in complete clinical remission if free from disease for at least 8 months after chemotherapy or surgery.18F-FDG PET was performed following standard procedures. 18F-FDG-PET was true positive in all cases of gastric MALT and non-MALT aggressive NHL with known active disease, while no pathological 18F-FDG uptake was evident in the subjects who were in complete clinical remission. The degree of 18F-FDG uptake (mean SUVmax values) in MALT lymphoma was much less intense in comparison to aggressive gastric NHL, suggesting a prognostic role of SUV calculation in gastric lymphomas. Our data demonstrate the significant accuracy of 18F-FDG-PET in detecting active disease in gastric lymphoma of both MALT and non-MALT NHL type. A higher SUV value appears to be related to a more aggressive disease. (author)