Comparison of 18F-FDG positron emission tomography and computed tomography in patients with colorectal carcinoma and lymphoma: our initial clinical experience.

Findings obtained by fluorine-18-fluorodeoxyglucose positron emission tomography (18F-FDG PET) and computed tomography (CT) were compared in patients with malignant lymphoma and colorectal carcinoma. In 14 malignant lymphoma patients, 16 18F-FDG PET procedures were performed to assess chemotherapy and/or radiotherapy outcome (remission). One patient with clinically overt relapse of non-Hodgkin's lymphoma underwent PET to assess disease dissemination prior to prescribing second-line chemotherapy. Two patients were submitted to PET on two occasions. PET pointed to residual disease in six of 14 patients and was inconclusive in one patient. These patients underwent computed tomography (CT), some of them before and others after PET examination. Then PET and CT findings were compared and therapeutic response, i.e. disease remission was assessed. The signs of residual disease were present in four and absent in nine patients, whereas inconclusive findings in terms of residual disease were recorded in one patient. Although our initial clinical experience was acquired in quite a small number of patients, CT modified clinical evaluation of residual disease in two patients and should be included along with PET in diagnostic work-up of these patients.