Imaging, QoL and Patient-Reported Outcome and Supportive Care

(OA-19) Prospective Evaluation of Response Assessment in Newly-Diagnosed Multiple Myeloma with Combined use of 18F-FDG-PET/CT, Whole-Body Diffusion-Weighted MRI and MRD by Next-Generation Sequencing

Wednesday, September 17, 2025

16:50 - 17:00 East Coast USA Time

Location: Room 701

Abstract Presenter(s)

Marco Talarico, marco.talarico

Hematologist and PhD Student
Università di Bologna - IRCCS Azienda Ospedaliero-Universitaria di Bologna, Istituto di Ematologia "Seràgnoli"
Bologna, Emilia-Romagna, Italy

Introduction: The IMWG recommends integration of hematologic response with minimal residual disease (MRD) assessment, both in bone marrow (BM) by next-generation sequencing (NGS) or flow, and by imaging. 18F-FDG-PET/CT currently represents the recommended technique in this setting; its use has been standardized following IMPeTUs criteria. A role of other functional imaging techniques, particularly of whole-body diffusion-weighted MRI (WB-DW-MRI), is emerging. Specific response assessment categories (RACs) have been lately proposed by MY-RADS guidelines. We present a prospective single-center study aimed at comparing PET/CT and WB-DW-MRI during diagnosis/staging of newly-diagnosed multiple myeloma (NDMM) and in defining treatment response, in association with BM MRD.

Methods:

Patients (pts) undergo PET/CT and WB-DW-MRI at baseline (B). Techniques resulting positive (pos) at B are repeated before maintenance therapy (transplant-eligible pts) or after 1 year of therapy (transplant-ineligible pts). Pts achieving ≥ very good partial response (VGPR) undergo MRD assessment by NGS. Interpretation of the imaging techniques is based on IMPeTUs and MY-RADS guidelines.

Results: Between October 2022 and March 2025, 131 NDMM pts were enrolled. Among pts with CT-assessed bone disease (64%), MRI was pos in 100% and PET in 89%; in the remaining 36%, MRI was negative (neg) in 49% (none with PET-assessed focal lesions, FLs) and pos in 51%. MRI detected FLs and paraskeletal disease (PSD) in more NDMM pts than PET (FLs: 76% vs 57%, p=0.001; PSD: 30% vs 23%, p=0.001); concordance was perfect in detecting extramedullary disease (EMD) (2%, k=1) and slight in detecting diffuse disease (DD) (24% vs 34%, p=0.001, k=0.4). By WB-DW-MRI, DD was related to higher % of BM plasma cells (p=0.002), lower Hb (p=0.002), higher concentration of M protein in serum (p=0.02) and urines (p=0.01); presence of >3 FLs was related to R-ISS 3 (p=0.001) and lower Hb (p=0.02). To May 2025, 50 pts reached the re-evaluation phase. 26 pts (52%) achieved complete response (CR), 19 (38%) VGPR, 4 (8%) PR, 1 (2%) was non-secretory. MRD was available for 19 pts, resulting neg in 10 (53%) and pos in 9 (47%). 32 pts had pos PET at B: 28 (88%) achieved metabolic CR, 1 (3%) metabolic PR, 3 (9%) metabolic stability or progression. 41 pts had pos WB-DW-MRI at B: 37 (90%) responded (RAC1-2), 4 (10%) had stable or progressive disease (RAC3-5). Among 32 pts repeating both techniques, 30 (94%) had concordant scans (k=0.6). Among 28 pts achieving ≥ VGPR and imaging response by both techniques, MRD assessment was available for 13 pts, resulting neg in 8 (62%) and pos in 5 (38%).

Conclusions: Our data support combined use of PET/CT and WB-DW-MRI for MM staging at B and show a good concordance in response assessment, suggesting a potential alternative use in this setting. Updated data with extended follow-up and regarding imaging response and MRD assessment will be presented at the meeting.