Abstract
To determine the value of diffusion-weighted MRI (DWI-MRI) for pretherapeutic imaging of fluorodeoxyglucose (FDG)-avid lymphoma and lymphoma with variable FDG avidity. Treatment-naïve patients with lymphoma who were referred for whole-body staging were included in this prospective study. Group A included patients with FDG-avid lymphoma (e.g., Hodgkin, diffuse large B-cell, and follicular lymphoma), whereas Group B included patients with lymphoma of variable FDG avidity [e.g., extranodal marginal zone B-cell lymphoma of the mucosa-associated lymphoid tissue (MALT)]. All patients underwent DWI-MRI and 18F-FDG- positron emission tomography/computed tomography (PET/CT). Region-based sensitivity and agreement with Ann Arbor staging, relative to the reference standard, were calculated for DWI-MRI, and, in Group B, also 18F-FDG-PET/CT and contrast-enhanced (CE-) CT. In Group A (100 patients), DWI-MRI had a region-based sensitivity of 97%, and with regard to staging, agreed with the reference standard in 94 of 100 patients (κ, 0.92). In Group B (40 patients; 38 MALT lymphomas and 2 small lymphocytic lymphomas/chronic lymphocytic leukemias), DWI-MRI, 18F-FDG-PET/CT, and CE-CT had region-based sensitivities of 94.4%, 60.9%, and 70.7%, respectively. With regard to staging in Group B, DWI-MRI, 18F-FDG-PET/CT, and CE-CT agreed with the reference standard in 37 of 40, 26 of 40, and 24 of 40 patients, with κ values of 0.89, 0.52, and 0.43, respectively. In patients with FDG-avid lymphoma, DWI-MRI seems to be only slightly inferior to 18F-FDG-PET/CT with regard to pretherapeutic regional assessment and staging. In patients with lymphoma subtypes that show a variable FDG avidity (e.g., MALT lymphoma), DWI-MRI seems to be superior to both 18F-FDG-PET/CT and CE-CT.
Highlights
Positron emission tomography/computed tomography (PET/CT) after application of the radiotracer 18F-fluorodeoxyglucose (FDG) is the current functional imaging method of choice for the most common lymphoma subtypes, because it visualizes the elevated glucose metabolism in these lesions [1,2,3,4,5,6]
With regard to staging in Group B, diffusion-weighted MRI (DWI-MRI), 18F-FDG-PET/CT, and CE-CT agreed with the reference standard in 37 of 40, 26 of 40, and 24 of 40 patients, with k values of 0.89, 0.52, and 0.43, respectively
Our results suggest that in patients with FDG-avid lymphoma [e.g., Hodgkin lymphoma, diffuse large B-cell lymphoma (DLBCL), and follicular lymphoma], diffusion-weighted imaging (DWI)-MRI may be an alternative to 18FFDG-PET/CT, which is the current imaging reference standard, for pretherapeutic staging
Summary
Positron emission tomography/computed tomography (PET/CT) after application of the radiotracer 18F-fluorodeoxyglucose (FDG) is the current functional imaging method of choice for the most common lymphoma subtypes, because it visualizes the elevated glucose metabolism in these lesions [1,2,3,4,5,6]. Certain lymphoma subtypes, such as extranodal marginal zone B-cell lymphoma of the mucosa-associated lymphoid tissue (MALT), are frequently not FDG-avid [1, 7,8,9,10], and 18F-FDGPET/CT is generally not recommended in these cases [11]. In the latter lymphoma subtypes, contrast-enhanced (CE) CT, which relies exclusively on morphology, is the standard imaging test, because no functional technique has been established so far
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