A Prospective Study Comparing CT, PET and PET/CT for Pre-Treatment Clinical Staging in Non-Hodgkin9s and Hodgkin9s Lymphoma.

Abstract 3920 Poster Board III-856 Introduction Accurate staging is critical in patients with lymphoma. Despite the lack of functional information CT remains the standard imaging technique based on anatomic criteria. PET with FDG provides functional evaluation but lacks of specificity due to the absence of anatomic landmarks. We have prospectively compared the accuracy of combined PET/CT with that of CT and PET alone at initial staging in lymphoma patients. Material and Methods. Patients with newly diagnosed lymphoma were prospectively included in the study. All patients underwent conventional staging studies which included clinical history, physical examination, laboratory work-up, biopsy of enlarged lymph node and of the iliac crest bone marrow, and PET/CT (either with full-dose contrast enhanced CT (FD PET/CT) and with low-dose non-enhanced CT (LD-PET/CT)) before starting therapy. The combined results of the clinical and imaging studies and the results of biopsies of suspected sites involved with lymphoma, when possible, formed the basis of our reference standard. The primary objective of the study was to address the accuracy of the PET/CT examination in clinical staging. For each patient, staging was assessed according to the Ann Arbor classification system on the basis of CT, PET images alone and the PET/CT images. The results were then compared with the true clinical stage based on the reference standard. Secondary objectives were: evaluation of the influence of clinical staging with PET/CT in the treatment approach, assessment of the efficacy of PET in evaluating bone marrow (BM) involvement, and definition of the accuracy of PET/CT imaging in the staging of different histologic subgroups. Results. 108 patients (64 female and 44 male; mean age 50 years; range 18-75 years) were included in the study. 76 patients had NHL and 32 had HL. 36% of the patients (28) had DLBCL whereas 18% (14 patients) had Follicular lymphoma. Other subtypes of NHL accounted for less than 10%. 31 of HL patients had classic variants. True clinical stage for NHL patients was I (7), II (11), III (6) and IV (52), and for HL was II (17), III (4) and IV (10). Agreement in staging was statistically significant between the reference standard and the staging algorithms by CT (k=0.493 p Disclosures: No relevant conflicts of interest to declare.