Utility of camera-based FDG PET in the detection of recurrence in the follow-up of patients with non-Hodgkin's lymphomas

The aim of this study was to evaluate the usefulness of F-18 FDG coincidence(CoDe) PET using a dual-head gamma camera in the detection of recurrence in patients with non-Hodgkin's lymphomas after treatment. 39 CoDe-PET studies were performed in 24 patients with histologically proven non-Hodgkin's lymphomas for the follow-up evaluation after the remission. CoDe-PET began 60 minutes after the injection of 111-185 MBq of F-18 FDG in the fasting state of 6-12 hours. A whole trunk from cervical to inguinal regions or selected region were scanned in supine position. There was no attenuation correction made. CoDe-PET studies were evaluated visually and compared with the results of CT or MRI. The results of CoDe-PET and of CT or MRI were validated histologically of by radiological and clinical follow-ups for 1 year. Of 39 studies, 32 were validated. The overall sensitivity and specificity of CoDe-PET in the detection of recurrent lesions were 75% (6/8) and 83% (20/24), respectively. MRI or CT showed the sensitivity of 80% (4/5) and the specificity of 67% (8/12). There were three false positive and two false negative CoDe-PET results. There were 6 patients of confirmed recurrence. CoDe PET with FDG has slightly lower sensitivity than CT or MRI but much higher specificity in the detection of recurrent non-Hodgkin's lymphomas. However, CoDe PET revealed high negative predicted value in the follow-up of patients with non-Hodgkin's lymphomas after the therapy