Imaging of treatment response and minimal residual disease in multiple myeloma: state of the art WB-MRI and PET/CT

Abstract

Bone imaging has been intimately associated with the diagnosis and staging of multiple myeloma (MM) for more than 5 decades, as the presence of bone lesions indicates advanced disease and dictates treatment initiation. The methods used have been evolving, and the historical radiographic skeletal survey has been replaced by whole body CT, whole body MRI (WB-MRI) and [18F]FDG-PET/CT for the detection of bone marrow lesions and less frequent extramedullary plasmacytomas.Beyond diagnosis, imaging methods are expected to provide the clinician with evaluation of the response to treatment. Imaging techniques are consistently challenged as treatments become more and more efficient, inducing profound response, with more subtle residual disease. WB-MRI and FDG-PET/CT are the methods of choice to address these challenges, being able to assess disease progression or response and to detect “minimal” residual disease, providing key prognostic information and guiding necessary change of treatment.This paper provides an up-to-date overview of the WB-MRI and PET/CT techniques, their observations in responsive and progressive disease and their role and limitations in capturing minimal residual disease. It reviews trials assessing these techniques for response evaluation, points out the limited comparisons between both methods and highlights their complementarity with most recent molecular methods (next-generation flow cytometry, next-generation sequencing) to detect minimal residual disease. It underlines the important role of PET/MRI technology as a research tool to compare the effectiveness and complementarity of both methods to address the key clinical questions.

Myeloma Spine and Bone Damage Score (MSBDS) on Whole-Body Computed Tomography (WBCT): Multiple Reader Agreement in a Multicenter Reliability Study

“…In patients with confirmed MM, medical imaging can be used to localize the source of pain and to prevent any eventual complications that are usually related to bone destruction [ 21 ]. The focal lesions detected on medical imaging are a strong prognostic marker and mark the need for treatment, even in the absence of cortical bone destruction [ 22 , 23 , 24 ]. Despite the diagnostic value of CT for the detection of bone marrow lesions, it is limited and MRI is superior.…”

Metabolic Volume Measurements in Multiple Myeloma

“…They allow the assessment of the effects of the disease on the skeletal system and identify the presence of extramedullary disease. In the past, this included skeletal radiographic examinations, now largely replaced by CT, MRI and FDG-PET/CT [83][84][85][86][87].…”

“…Diffusion-weighted imaging (DWI) is a functional MRI imaging technique that reflects the rate of water diffusion between tissues. DWI is regarded as the most sensitive imaging technique for bone marrow lesions [87,97]. In parallel with FDG-PET, DWI allows quantitative assessments, such as measures related to the apparent diffusion coefficient (ADC) and volumetric measures such as total diffusion volume (tDV).…”

First-in-Humans Evaluation of Safety and Dosimetry of64Cu-LLP2A for PET Imaging

“…One of the overt features of MM is the presentation of diffuse infiltration and punctate focal lesions in the BM (7). Molecular PET and functional magnetic resonance imaging (MRI) are highly informative in the management of patients with MM, from initial diagnosis to therapy and longitudinal tumor monitoring (8), especially in the context of bone and BM involvement (9).…”