Role of Imaging in Lymphoma

Abstract

The lymphomas comprise approximately 5.0% of all malignancies and are the sixth most frequently occurring type of cancer in the Western world. The World Health Organization International Classification of Tumors recognizes more than 50 subtypes of lymphoma, based on histopathologic, immunohistochemical, cytogenetic, and molecular analyses. However, the three most common subtypes diffuse large B-cell lymphoma (DLBCL), follicular lymphoma, and Hodgkin lymphoma account for more than 60% of all cases. Computed tomography (CT), 18F-fluoro-2-deoxyglucose positron emission tomography (FDG-PET) and whole-body magnetic resonance imaging (MRI) are imaging techniques that may be used for several purposes in lymphoma management. The aim of this thesis was to explore the role of imaging in lymphoma in five different domains: the role of imaging in the evaluation of the bone marrow, the role of imaging in pretreatment risk assessment, the role of imaging in therapy response assessment, the role of imaging in lymphoma grading, and the role of imaging from the patient's perspective. The results show that FDG-PET is reasonably sensitive for the detection of bone marrow involvement in Hodgkin lymphoma. However, the role of FDG-PET in the evaluation of the bone marrow in DLBCL and follicular lymphoma is limited. Initial results show whole-body MRI to be comparable to FDG-PET for bone marrow assessment, but more research is needed to define its exact role. In DLBCL, tumor necrosis at baseline appears to be an independent risk factor of the NCCN-IPI score. Interim FDG-PET has some prognostic value in advanced-stage Hodgkin lymphoma, but it has no role in early-stage Hodgkin lymphoma, DLBCL and follicular lymphoma. End-of-treatment FDG-PET fails to identify a large proportion of patients with Hodgkin lymphoma and DLBCL who will experience treatment failure, which emphasizes that its role in this setting should be reconsidered, if not abandoned. Moreover, there is no evidence-based role for FDG-PET in the end-of-treatment evaluation of follicular lymphoma. FDG-PET performed at baseline is reasonably accurate in differentiating aggressive non-Hodgkin lymphoma from indolent non-Hodgkin lymphoma and Hodgkin lymphoma, but appears to be not reliable in differentiating indolent non-Hodgkin from Hodgkin lymphoma. Finally, patients with newly diagnosed lymphoma regard whole-body MRI as a more patient-friendly technique than CT.