Diffusion-Weighted MRI Could Guide Need for BMB in Newly Diagnosed Myeloma

According to data presented at the Lymphoma, Leukemia & Myeloma Congress, researchers have observed a moderate positive correlation between sacral ala bone marrow apparent diffusion coefficient (ADC) and plasma cell burden on bone marrow biopsy (BMB) in patients with newly diagnosed myeloma.

“Newer diffusion-weighted MRI sequences (DW-MRI) are frequently used to aid the detection of lesions and measurement of post-treatment response. However, key biomarkers utilised in treatment algorithms and prognostic tools (including plasma cell burden and marrow cellularity) rely on invasive [BMB] that has associated morbidity and may not be clinically appropriate for all patients,” wrote Devarshi Bhattacharyya, MPH, MSc, North Shore Hospital, Auckland, New Zealand, and colleagues.

Seeking to determine whether ADC of bone marrow measured via DW-MRI could be used to predict key biomarkers in patients with newly-diagnosed myeloma and alleviate the need for BMB in certain cases, Dr Bhattacharyya et al conducted a study of 33 patients (mean age, 66 years) between April 2019 and June 2020.

All patients were newly diagnosed with myeloma at North Shore Hospital, and underwent BMB and DW-MRI. Those who had previously been treated for myeloma or who have non-myeloma diagnoses were excluded from the study.

The investigators documented the presence or absence of myelomatous lesions and formally reviewed all BMB specimens. Using the electronic medical record, they also gathered and collated data regarding immunoglobulin isotype, marrow cellularity and plasma cell burden.

“Paired multivariate analysis was performed to determine the strength of correlation between the measured parameters using Pearson coefficients (r). Receiver-operator curves were drawn to determine the sensitivity and specificity values at different ADC thresholds,” Dr Bhattacharyya and co-investigators explained.

There was a median of 7 days between imaging and BMB, and bone marrow ADC values ranged from 120µm/s to 1330µm/s. Marrow cellularity ranged from 10% to 90%, and plasma cell burden ranged from 5% to 100%.

Approximately 20% of patients had MGUS as per International Myeloma Working Group (IMWG) criteria, and the remainder had smouldering or multiple myeloma.

According to the researchers, a moderate positive correlation between sacral ala ADC and plasma cell burden (r = 0.59; P <.05) was observed, although the overall correlation with BMB biomarkers varied at other locations. Sensitivity was 82% and specificity to predict a ≥60% plasma cell burden on BMB was 83% vis-à-vis a sacral ala ADC threshold of ≥430µm/s.

“Our findings reveal a moderate positive correlation between sacral ala bone marrow ADC and plasma cell burden on BMB, with more variability at other sites and with other biomarkers,” Dr Bhattacharyya, and colleagues reported.

“This has potential as a clinical indication to perform BMB in patients for whom this important diagnostic test would otherwise be deferred on medical grounds,” they concluded.—Hina Porcelli

Bhattacharyya D, Agraval J, Chan H. Can Diffusion-Weighted Magnetic Resonance Imaging Predict Key Biomarkers In Newly-Diagnosed Myeloma? Presented at: the Lymphoma, Leukemia & Myeloma Congress; October 21-24, 2020; virtual. Abstract P-02.