Abstract and Introduction
Computed tomography (CT), 18F-fluorodeoxyglucose (FDG)-PET and the hybrid FDG-PET/CT are the most commonly used diagnostic tools for the initial staging and treatment response assessment of malignant lymphomas. MRI techniques such as whole-body MRI and diffusion-weighted imaging may be good radiation-free alternatives to FDG-PET/CT, which may be particularly relevant for children. Diffusion-weighted imaging is characterized by high sensitivity for the detection of lesions and allows quantitative assessment of diffusion that may aid in the evaluation of malignant lymphomas. This article will review the value of these emerging MRI techniques for the staging and response assessment of malignant lymphoma. Furthermore, we will discuss some additional imaging techniques that are the subject of ongoing research and may have potential for future clinical application.
The malignant lymphomas, Hodgkin's lymphoma (HL) and non-Hodgkin's lymphoma (NHL), comprise approximately 5–6% of all malignancies in adults and account for 10% of childhood cancers. In adults, the vast majority of malignant lymphomas are NHLs. In children, two-thirds of malignant lymphomas are NHLs. Once the diagnosis of HL or NHL has been established histologically by means of (excision) biopsy, the anatomic extent of disease and tumor burden have to be assessed because they determine the prognosis and the choice of treatment. Current treatment regimens consisting of chemotherapy and involved field radiotherapy result in tumor control in more than 80% of HL patients and in the majority of patients with NHL.[2,3] Contemporary treatment protocols pursue two important goals; first, they maximize the chance of cure and second, they minimize late toxicity, such as infertility, premature menopause, cardiac disease and, most importantly, risk of second neoplasms. To achieve these goals, an accurate staging by imaging is essential because it determines the choice of treatment. Furthermore, imaging plays a vital role in monitoring the response to therapy and in the detection of relapse. Today, imaging for staging and response assessment of malignant lymphomas is performed by computed tomography (CT) or 18F-fluorodeoxyglucose (FDG)-PET, which can either be applied as standalone imaging modalities or as one integrated modality (FDG-PET/CT). A major disadvantage of CT and FDG-PET is that these imaging modalities are accompanied by a significant amount of radiation exposure, which may induce second neoplasms.[5–10] It is argued that the radiation exposure by CT and FDG-PET will have a small effect on the occurrence of long-term complications compared with the effect caused by the toxicity of chemo- and radio-therapy. However, the radiation exposure of these imaging modalities cannot be neglected, as patients undergo repeated imaging during the course of disease and follow-up. Therefore, reduction of radiation exposure during imaging remains important, in combination with reduction of therapy toxicity. This is of particular concern in children, as their young, rapidly dividing tissues are more sensitive to radiation-induced effects. In addition, children will have many years ahead during which secondary tumors may develop.
Magnetic resonance imaging is a radiation-free imaging method with a good spatial resolution and excellent soft-tissue contrast. New MRI techniques, such as whole-body MRI and diffusionweighted imaging (DWI), may be potential attractive alternatives to CT and FDG-PET for the staging and treatment response assessment of cancers. This article aims to provide an overview of the current literature on MRI for the staging and response assessment of malignant lymphomas. First, current methods of initial staging and treatment response assessment, by means of CT and FDG-PET, will be summarized, after which the role of various MRI techniques in imaging patients with malignant lymphoma will be discussed.
Expert Rev Hematol. 2011;4(2):161-171. © 2011 Expert Reviews Ltd.
Cite this: Magnetic Resonance Imaging of Malignant Lymphoma - Medscape - Apr 01, 2011.