Christian Waldherr MD, PRESENTER: Nothing to Disclose

Abstract: HTML Purpose: In indolent and aggressive lymphoma, correct stage and number of extranodal sites is essential to predict outcome. Previous studies proofed that FDG-PET predicts the outcome of lymphoma patients undergoing salvage chemotherapy (HDT) followed by autologous stem cell transplantation (ASCT) with higher accuracy than CT. Today, it is unknown whether combined PET/CT provides additional diagnostic and prognostic information. The aim of this ongoing prospective study is to determine the diagnostic and prognostic value of PET, CT and PET/CT in patients after salvage chemotherapy and before ASCT. Methods and Materials: Of 30 patients to be studied, 12 patients with relapsed Hodgkins Disease (HD); nodular sclerosing (n=5), mixed cell(n=1) or Non-Hodgkins lymphoma (NHL: n=6; diffuse large cell: n=4, anaplastic large cell: n=1, T-cell: n=1) underwent PET/CT 5-13 weeks after start of salvage chemotherapy, prior to ASCT. Observers blinded for the complementary imaging modalities interpreted CT, PET and multi-modality PET/CT images independently. PET and CT lesions classified as suspicious or definitively malignant were categorized as positive for residual disease while all other loci were considered negative. Differences in patient stage as derived from PET, CT and PET/CT were determined, and a lesion-by-lesion analysis was performed. Sensitivity, specificity, and predictive accuracy of PET, CT and PET/CT will be presented after a prolonged follow up. Results: Combined PET/CT imaging identified 63 lesions. Thirty were metabolically active and thus considered malignant (48%), while 33 were PET negative and thus considered benign (52%). CT alone revealed 47 mass lesions in 11/12 patients. Of these, 42 (89%) were considered malignant and 5 (11%) benign. PET alone revealed 38 hyper-metabolic lesions in 11/12 patients. Concordantly negative PET and CT findings were present in 1 patient. Four hyper-metabolic PET lesions in 4 patients and 23 CT lesions in 10 patients were regarded as false positive (FP) on PET/CT interpretation. PET localized 5 malignant lesions anatomically wrong. PET/CT interpretations changed PET conclusions about remnant lymphoma or disease free stage in 4 patients (33%), CT conclusions in 2 patients (17%). Conclusion: The initial results from this prospective study in patients with aggressive lymphoma suggest that PET/CT adds clinically pertinent information over CT and PET alone in about 25% of patients, due to a reduced number of apparently false positive or negative CT and PET findings. (J.C. is a consultant for CPS Innovations.) Questions about this event email: cwaldherr@mednet.ucla.edu

Waldherr MD, C, CT, PET, and PET/CT for Predicting the Outcomeof Lymphoma Patients.  Radiological Society of North America 2003 Scientific Assembly and Annual Meeting, November 30 - December 5, 2003 ,Chicago IL. http://archive.rsna.org/2003/3105021.html