be
Juweid et al. evaluated the impact of integrating PET into the IWG criteria in a retrospective study of 54 patients with diffuse large B-cell NHL who had been treated with an anthracycline-based regimen.
PET
• False-positive: - Thymic hyperplasia - Infection - Inflammation - Sarcoidosis - Brown fat Other causes of false-positive scans should ruled out. • False-negative: - Resolution of the equipment and technique - Variability of FDG avidity among histologic subtypes
J Clin Oncol 25:571-578. © 2007 by American Society of Clinical Oncology
PET- PET/CT
• PET using [18F]fluorodeoxyglucose (FDG, a radioactive derivative of glucose, is an advanced imaging tool, based on the increased glucose consumption of cancer cells), has emerged as a powerful functional imaging tool for staging, restaging, and response assessment of lymphomas. • The advantage of PET over conventional imaging techniques, such as TC or RMN, is its ability to distinguish between viable tumor and necrosis or fibrosis in residual mass(es) often present after treatment. A recently developed integrated PET/CT system, which combines a PET camera and CT scanner in a single session, has overcome these drawbacks by providing both anatomical and functional imaging at the same position. PET/CT has become the new standard approach to imaging in the diagnosis and management of many cancer patients.
• Allowing for comparisons among studies • Facilitating the identification of more effective therapies
The widely used IWG criteria for response assessment of lymphoma are based predominantly on CT. It became clear that the International Working Group criteria warranted revision, because of identified limitations and the increased use of :
Use of Positron Emission Tomography for Response Assessment of Lymphoma: Consensus of the Imaging Subcommittee of International Harmonization Project in Lymphoma
Standardization of PET and CT Imaging Parameters
Patients undergoing PET imaging should receive an FDG dose of 3.5 to 8 MBq/kg of body weight, with a minimum dose of 185 MBq in adults (5 mCi) and 18.5 MBq (0.5 mCi) in children. Patients should have fasted for at least 4 hours before FDG injection. Blood glucose level should not exceed 200 mg/dL at the time of FDG injection. If the blood glucose exceeds this level, the FDG-PET study should be rescheduled and an attempt made to control the blood sugar. Whole-body acquisition using a PET or PET/CT system should encompass at least the region between the base of the skull and themed thigh, and can be acquired in either two- or three-dimensional mode. Whole-body imaging should begin 50-70 minutes after the administration of FDG. The reconstructed PET or PET/CT images must be displayed on a computer workstation so that transaxial, sagittal, and coronal images can be viewed simultaneously.
Definitions of End Poind Point Overall survival Event-free survival Response Category All patients CR, CRu, PR Definition Death from any cause Failure or death from any cause Disease progression or death from NHL Time to relapse Time to relapse or progression Time when new treatment is needed Death related to NHL Point of Measurement Entry onto trial Entry onto trial
“REVISED RESPONSE CRITERIA FOR MALIGNANT LYMPHOMA”
J Clin Oncol 25:579-586. © 2007 by American Society of Clinical Oncology
Cheson et al, J Clin Oncol 17:1244, 1999 In 1999, an International Working Group (IWG) of clinicians, radiologists, and pathologists with expertise in the evaluation and management of patients with Lymphoma published guidelines for response assessment and outcomes measurement.
Response Criteria for Lymphoma
Response Category CR CRu Physical Examination Normal Normal Normal PR Normal Normal Decrease in liver/spleen Relapse/ progression Enlarging liver/spleen; new sites Lymph Nodes Lymph Node Masses Normal Normal Normal Normal ≥50% decrease ≥ 50% decrease New or increased Normal Normal > 75% decrease Normal ≥50% decrease ≥50% decrease New or increased Bone Marrow Normal Indeterminate Normal or indeterminate Positive Irrelevant Irrelevant Reappearance
1. [18F] fluorodeoxyglucose-positron emission tomography (PET), 2. immunohistochemistry (IHC), 3. flow cytometry, 4. molecular biology
“REVISED RESPONSE CRITERIA FOR MALIGNANT LYMPHOMA”
J Clin Oncol 25:579-586. © 2007 by American Society of Clinical Oncology