Imaging of malignant lymphomas with F-18FDG coincidence defection positronemission tomography

Purpose: The authors evaluated the utility of F-18 fluorodeoxyglucose (FDG) coincidence detection (CoDe) positron emission tomography (PET) for stagin g, post-treatment evaluation, and follow-up assessment of patients with mal ignant lymphomas. Materials and Methods: Fifty-eight patients with histologically proved mali gnant lymphomas (4 Hodgkin's disease, 54 non-Hodgkin's lymphoma) underwent CoDe PET using F-18 FDG. CoDe PET was performed using a dual-head gamma cam era equipped with coincidence detection circuitry. Of the 87 CoDe PET studi es, 26 were performed for staging, 38 for post-treatment evaluation, and 23 for follow-up evaluation of recurrence. The entire trunk, from the cervica l to the inguinal regions, or selected regions were scanned with the patien t in the supine position. No attenuation correction was made and reconstruc tion was performed using filtered backprojection rather than iterative reco nstruction. CoDe PET findings were compared with corresponding results of c omputed tomographic (CT) and magnetic resonance imaging (MRI), tissue biops y, or clinical follow-up. Results: For staging, 52 sites were positive on CoDe PET or CT-MRI, CoDe PE T detected 49 sites (94%), and CT-MRI showed 47 sites (90%). CoDe PET detec ted five more lymphomatous lesions and missed three lesions. For post-treat ment evaluation, CoDe PET showed a positive predictive value of 100% and a negative predictive value of 83%, but the validated cases numbered only 11. For follow-up for recurrence, CoDe PET had a negative predictive value of 90%, but frequent false-positive findings were noted in the head and neck r egion as a result of underlying inflammatory changes. Conclusions: For staging, FDG CoDe PET alone without attenuation correction is not sensitive enough to be used as an independent imaging method, espec ially for small abdominal lesions, However, it appears to be an accurate me thod for assessing residual disease and for patient follow-up.