The utility of newer imaging techniques as predictors of clinical outcomes in multiple myeloma

Head-to-Head Comparison between FDG and 11C-Methionine in Multiple Myeloma: A Systematic Review

The aim of this systematic review is to provide a comprehensive overview of the existing literature, comparing ¹⁸F-fluorodeoxyglucose (FDG) and ¹¹C-methionine (MET) for the imaging of multiple myeloma (MM) with positron emission computed tomography (PET/CT). Relevant studies published from 2013 up to March 2023 were selected by searching Scopus, PubMed, and Web of Science. Selected imaging studies were analyzed using a modified version of the critical Appraisal Skills Programme (CASP). Ten studies encompassing 335 patients were selected. On a patient-based analysis, MET sensitivity ranged between 75.6% and 100%, resulting higher than that measured for FDG (0-100%). MET outperformed FDG for the detection of focal lesions, diffuse bone marrow involvement and mixed patterns. PET-derived parameters resulted higher for MET than for FDG, with a strong correlation with clinical variables (e.g., monoclonal component and beta-2-microglobulin levels, bone marrow infiltration, etc.), although FDG maintained a prognostic impact on outcome prediction. When compared to other tracers or imaging modalities, MET showed stronger correlation and inter-observer agreement than FDG. Although biased by the small cohorts and requiring confirmation through multicenter studies, preliminary findings suggest that MET-PET should be preferred to FDG for PET imaging of MM, or alternatively used as a complementary imaging modality. Some issues, such as tracer availability and the role of MET with respect to other emerging tracers (i.e., ⁶⁸Ga-pentixafor, ¹⁸F-FACBC and ¹⁸F-FET), should be the topic of further investigations.

Fat fraction quantification of lumbar spine: comparison of T1-weighted two-point Dixon and single-voxel magnetic resonance spectroscopy in diagnosis of multiple myeloma

PURPOSE

We aimed to investigate the value of T1-weighted two-point Dixon technique and single-voxel magnetic resonance spectroscopy (MRS) in diagnosis of multiple myeloma (MM) through quantifying fat content of vertebral marrow.

METHODS

A total of 30 MM patients and 30 healthy volunteers underwent T1-weighted two-point Dixon and single-voxel MRS imaging. The fat fraction map (FFM) was reconstructed from the Dixon images using the equation FFM = Lip/In, where Lip represents fat maps and In represents in-phase images. The fat fraction (FF) of MRS was calculated by using the integral area of Lip peak divided by the sum of integral area of Lip peak and water peak.

RESULTS

FF values measured by the Dixon technique and MRS were significantly decreased in MM patients (45.99%±3.39% and 47.63%±4.38%) compared with healthy controls (64.43%±0.96% and 76.22%±1.91%) (P < 0.001 with both methods). FF values measured by Dixon technique were significantly positively correlated to those measured by MRS in MM (r = 0.837, P < 0.001) and healthy control group (r = 0.735, P < 0.001), respectively. There was no significant difference between area under the curve (AUC) obtained by the Dixon technique (0.878±0.047; range, 0.785 to 0.971; optimal cutoff, 56.35 for healthy controls vs. MM) and MRS (0.883±0.047; range, 0.791 to 0.974; optimal cutoff, 61.00 for healthy controls vs. MM). The ability of Dixon technique to differentiate MM group from healthy controls was equivalent to single-voxel MRS.

CONCLUSION

Regarding detection of fat contents in vertebral bone, T1-weighted two-point Dixon technique exhibited equivalent performance to single-voxel MRS in the diagnosis of multiple myeloma. Moreover, two-point Dixon is a more convenient and stable technique for assessing bone marrow changes in MM patients than single-voxel MRS.

Comprehensive Updates in the Role of Imaging for Multiple Myeloma Management Based on Recent International Guidelines

The diagnostic and treatment methods of multiple myeloma (MM) have been rapidly evolving owing to advances in imaging techniques and new therapeutic agents. Imaging has begun to play an important role in the management of MM, and international guidelines are frequently updated. Since the publication of 2015 International Myeloma Working Group (IMWG) criteria for the diagnosis of MM, whole-body magnetic resonance imaging (MRI) or low-dose whole-body computed tomography (CT) and ¹⁸F-fluorodeoxyglucose positron emission tomography/CT have entered the mainstream as diagnostic and treatment response assessment tools. The 2019 IMWG guidelines also provide imaging recommendations for various clinical settings. Accordingly, radiologists have become a key component of MM management. In this review, we provide an overview of updates in the MM field with an emphasis on imaging modalities.

Evaluation of bone marrow infiltration in multiple myeloma using whole-body diffusion-weighted imaging and T1-weighted water-fat separation Dixon

Background

Multiple myeloma (MM) is a blood cancer caused by the unlimited proliferation of intramedullary plasma cells. The presence of focal lesions (FLs) is presumed to be a more relevant factor for patient outcomes and risk distribution than diffuse bone marrow signal abnormalities. Signal changes in these FLs also have a good correlation with prognosis. As the cell density increased, a lower apparent diffusion coefficient (ADC) value was found with the diffusion-weighted imaging (DWI) sequence. Therefore, whole-body magnetic resonance imaging (MRI) with DWI sequences is sensitive to cell density and viability and may be vital for disease detection and therapy response assessments. However, the correlation between the DWI signal and the degree of bone destruction and the proportion of bone marrow plasma cells (BMPC) was still unclear in patients with MM. Water-fat separation MRI is used mainly for evaluating liver and bone marrow fat quantification, and fat quantification in other diseases. Meanwhile, it is also possible to assess the extent of bone marrow invasion in medullary lesions. This study aimed to investigate the correlation between ADC values from whole-body DWI and water/fat MRI signals from T1-weighted water-fat separation in evaluating bone marrow infiltration in patients with MM.

Methods

The study included 35 patients with MM who underwent whole-body DWI and T1-weighted water-fat separation Dixon examinations before therapy. The ADC values, normalized fat signal intensity (nMfat), normalized water molecular signal intensity (nMwater), and normalized fat fraction (nFF) of the thoracolumbar spine was measured in FLs and the normal-appearing bone marrow (NABM). The differences in values were compared using the independent-samples t-test. The correlation between ADC values and water-fat MRI signals was estimated using the Pearson or Spearman correlation test. The correlation between the MRI above parameters and proportions of BMPC was also explored.

Results

Statistically significant differences were found between the mean ADC values in FLs and NABM (0.72 vs. 0.33 mm²/s, P<0.0001). Significantly elevated nMwater values and decreased nMfat and nFF values were observed in FLs; no correlations were found in NABM (P>0.05). The ADC value highly correlated with nMfat and nFF values and moderately with the nMwater value in FLs (r=-0.899, -0.834, 0.642, respectively, P<0.0001). Correlations were also observed between the proportion of BMPC and MRI parameters in MM (r=0.984, 0.716, -0.938, and -0.905, respectively, P<0.05).

Conclusions

The ADC value combined with water-fat separation parameters could be used for evaluating thoracolumbar bone marrow infiltration in MM. All parameters correlated with the proportion of BMPC, which helped assess the early response in MM therapy.

Advances in whole body MRI for musculoskeletal imaging: Diffusion-weighted imaging

Recent advances in imaging technology have enabled the acquisition of anatomical and functional imaging from head to toe in a reasonably short scan time. Accordingly, whole body magnetic resonance imaging (WB-MRI) and diffusion-weighted imaging (WB-DWI) have gained recent attention for the management of musculoskeletal problems such as bone tumors and rheumatologic diseases. WB-MRI is especially useful in diagnosing systemic or widespread disease requiring whole body evaluation, such as bone metastases, multiple myeloma, lymphoma, neurofibromatosis, and spondyloarthropathies. Among WB-MRI sequences, the WB-DWI technique greatly increases the value of WB-MRI in the evaluation of disease extent and characterization as well as treatment monitoring. In support of the utilization of WB-MRI and WB-DWI in orthopedic clinics for various musculoskeletal diseases, we provide an overview of the technical aspects of WB-MRI and WB-DWI and their clinical applications in musculoskeletal tumors and rheumatic diseases.

Deep Response in Multiple Myeloma: A Critical Review

Novel and more effective treatment strategies against multiple myeloma (MM) have significantly prolonged patients' survival and raised interest in the depth of response and its association with clinical outcome. Minimal residual disease (MRD) has emerged as one of the most relevant prognostic factors in MM and should be included in a new definition of complete response (CR). Although further standardization is still required, MRD monitoring should be applied in prospective clinical trials as a sensitive tool to compare and evaluate the efficacy of different treatment strategies, particularly in the consolidation and maintenance settings, and implement individualized therapy-monitoring approaches. Here, we review current definition of deep response in MM, advantages and limitations of current MRD assessment assays, clinical evidences for MRD monitoring as a prognostic tool for therapeutic decisions in MM, and challenges to develop uniform criteria for MRD monitoring.

The comprehensive clinical management of multiple myeloma and related-plasma cell disorders

Whilst we think of multiple myeloma and related plasma cell disorders as incurable to date, never before has there been such hope and enthusiasm about advances in the research and treatment of these various diseases. Translational research is very much at the forefront of progress for further refining targeted therapies and continuing to improve clinical efficacy. Whilst some of these advances in the last decade have been truly dramatic in their scope and timing, it is also worth noting that relatively incremental changes have favorably impacted on patient outcome, and this comprehensive clinical management review captures these accordingly. We hope therefore that this concise overview will give readers, be they specialist hemato-oncologists, or other providers and researchers in the field, an enlightening insight into the exciting future of therapeutic opportunities, as well as a practical 'hands on' approach.

[Use of whole-body diffusion-weighted magnetic resonance imaging for the diagnosis of and therapeutic response in multiple myeloma]

INTRODUCTION

Multiple myeloma is an incurable neoplastic disorder of B cells characterized by diffuse bone marrow infiltration, circumscribed bone lesions, and soft-tissue spreading. The role of novel functional imaging techniques in multiple myeloma includes initial staging of the disease, detection and characterization of complications, and evaluation of the response to treatment.

AIM

The authors present their 2 and a half-year experience with diffusion-weighted magnetic resonance imaging in staging and follow up of patients with multiple myeloma.

METHOD

Conventional T1 weighted, T2 weighted fat suppressed and 2 b-values diffusion-weighted sequences were performed from skull base to symphysis in 27 patients suspected to have multiple myeloma. Apparent diffusion coefficient calculation was carried out in 3 cases. The final diagnosis of multiple myeloma was verified by bone-marrow biopsy.

RESULTS

In 13 cases magnetic resonance imaging revealed the suspected disease. In one patient magnetic resonance imaging failed to detect the disease because of metallic artifacts. In 6 cases diffusion-weighted sequences showed additional information about bone-marrow infiltration.

CONCLUSIONS

Diffusion-weighted magnetic resonance imaging with conventional sequences is a useful and promising functional imaging modality in the early diagnosis of myeloma multiple.