A prospective comparison of 18F-fluorodeoxyglucose positron emission tomography-computed tomography, magnetic resonance imaging and whole-body planar radiographs in the assessment of bone disease in newly diagnosed multiple myeloma

Ga-68 Pentixafor PET/CT in multiple myeloma and its correlation with clinical parameters: institutional pilot study

OBJECTIVE

This study evaluates the role of Ga-68 Pentixafor PET/CT in staging and follow-up of multiple myeloma (MM) and its correlation with clinical parameters.

METHODS

Thirteen participants (9 males, 4 females; median age: 65 years) with MM were recruited in this prospective observational study. Six participants were included for staging evaluation, seven were included for follow-up evaluation, and underwent Ga-68 Pentixafor PET/CT. Focal PET-positive bone marrow lesions or diffuse bone marrow uptake (uptake more than liver) was considered a positive scan. The quantitative variables like SUVmax, SUVmean, total bone marrow volume and uptake (TBMV & TBMU) and tumor to background ratio (TBRmax) were obtained. Durie Salmon Plus Staging (DSPS) was used for MM staging by PET/CT and was compared with the International Staging System (ISS). Statistical comparison was performed between PET/CT quantitative variables and laboratory parameters.

RESULTS

Twelve participants (12/13) had positive Ga-68 Pentixafor PET/CT, among which one was diagnosed to have anemia of chronic disease. One participant (1/13) who was clinically negative on follow-up had negative Ga-68 Pentixafor PET/CT. The sensitivity, specificity, PPV and NPV of Ga-68 Pentixafor PET/CT in MM (95% CI) were observed to be 100%, 50%, 91.6% and 100%, respectively. The correlation between DSPS and ISS in the patients who came for staging scans was found to be statistically significant (p-value 0.02). In quantitative analysis, either of the quantitative variables in Ga-68 Pentixafor PET/CT was positively correlated with clinical parameters related to tumor burden like CRAB score, serum protein electrophoresis M-protein, beta 2 microglobulin, LDH, percentage of plasma cells infiltrates in bone marrow aspiration, ISS, serum free light chain and negatively correlated with hemoglobin, albumin (p < 0.5).

CONCLUSION

Ga-68 Pentixafor PET/CT is a promising tracer and the only available non-invasive tool to assess the whole-body disease burden of CXCR4 receptors in staging and follow-up of MM. In addition, it has a vital role in the development of CXCR4-targeted theranostics. Dual tracer imaging using F-18 FDG and Ga-68 Pentixafor PET/CT may help in evaluating tumor heterogeneity in MM and add prognostic value at diagnosis and follow-up.

68 Ga-Pentixafor PET/CT-Based Response Evaluation and its Prognostic Value in Multiple Myeloma: Comparison With IMWG and 18 F-FDG-Based Response

PURPOSE

68 Ga-Pentixafor PET/CT targets CXCR4 receptors and provides superior diagnostic accuracy in multiple myeloma (MM) compared with 18 F-FDG PET/CT. However, its role in response evaluation remains unexplored. We propose a 68 Ga-Pentixafor PET/CT-based response evaluation criterion and evaluate its utility compared with International Myeloma Working Group (IMWG) criteria and 18 F-FDG PET/CT-based response.

PATIENTS AND METHODS

In this prospective single-center study, 40 treatment-naive myeloma patients were recruited between February 2021 and April 2023. Both 68 Ga-Pentixafor and 18 F-FDG PET/CT were performed at baseline and at follow-up (7.2 mo-median). Response to treatment was evaluated using the proposed 68 Ga-Pentixafor PET/CT criteria and compared with responses assessed by IMWG and 18 F-FDG PET/CT. Progression-free survival (PFS) and overall survival (OS) were analyzed and compared using Kaplan-Meier survival curves.

RESULTS

Among the 40 newly diagnosed MM patients [median age: 56.5 years (IQR 45.25 to 63.75); 24 men], 68 Ga-Pentixafor PET/CT was positive in a greater proportion of patients than 18 F-FDG PET/CT [90% (36/40) vs. 67.5% (27/40); P =0.02] thus, adequately evaluated response in additional 27.5% (11/40) of cases. Using the proposed criteria for 68 Ga-Pentixafor PET/CT, significant differences in PFS were observed across response categories [complete response (CR)-not reached, partial response (PR)-26.2 mo, progressive disease (PD)-15.3 mo; P =0.001]. Among patients achieving ≥very good partial response (VGPR) as per IMWG, those with positive 68 Ga-Pentixafor PET/CT had shorter PFS compared with those with negative findings (median PFS: 34.2 mo vs. not reached; P =0.056), whereas no significant difference was noted with 18 F-FDG PET/CT ( P =0.68). In addition, on follow-up of patients with negative 18 F-FDG at the response, those with discordant 68 Ga-Pentixafor findings had significantly shorter PFS (17.73 mo vs. not reached; P =0.010) compared with those with concordant negative findings.

CONCLUSIONS

68 Ga-Pentixafor PET/CT offers a more accurate assessment of treatment response and prognosis in MM patients, adding valuable information beyond the IMWG and 18 F-FDG PET/CT-based criteria.

Multiple myeloma: What is the most cost-effective imaging strategy for initial detection of bone lesions?

OBJECTIVE

To determine the cost-effectiveness of different imaging modalities for initial detection of multiple myeloma (MM)-defining bone lesions.

METHODS

A Markov model from the health care system perspective for patients with MGUS was used to evaluate the incremental cost-effectiveness of five imaging techniques: skeletal survey (SS), low-dose computed tomography (LDCT), positron emission computed tomography (PETCT), and whole-body magnetic resonance imaging (WBMRI) with and without diffusion (DIFF). Model inputs, including probabilities, utilities, and costs were obtained from comprehensive literature review. Costs were estimated in 2024 U.S. dollars, effectiveness was measured in quality adjusted life years (QALYs), willingness-to-pay (WTP) threshold was set to $100,000/QALY, and timeframe of the simulation was 20 years. Model analyses included Monte Carlo microsimulation and probabilistic sensitivity analysis (PSA).

RESULTS

The most cost-effective imaging strategy was dependent on the number of patient risk factors for progression from MGUS to myeloma. At a WTP threshold of $100,000, for patients with no risk factors for progression, LDCT amassed the greatest net monetary benefit (NMB) ($1,030,913.57) while incurring the second lowest costs ($44,870.73). For patients with 1 or 2 risk factors for progression, WBMRI + DIFF amassed the greatest NMB (1 risk factor: $802,637.30, 2 risk factors: $664,430.36). WBMRI and PETCT were absolutely dominated in all cases. PSA also found that the most cost-effective strategy was dependent on the WTP threshold.

CONCLUSION

Our model suggests that LDCT and WBMRI + DIFF can be the most cost-effective imaging strategies for the initial diagnosis of MM in patients, depending on the number of risk factors for progression.

Prognostic value of [18F]fluorodeoxyglucose-PET/MRI(CT) novel interpretation criteria (IMPeTUs) in multiple myeloma

PURPOSE

[18F]fluorodeoxyglucose (FDG)-PET is a powerful tool to evaluate prognosis in multiple myeloma (MM). The development of systematic and reproducible standard interpretation criteria is crucial for the effective application of FDG-PET in MM. A new set of criteria-Italian Myeloma criteria for PET Use (IMPeTUs)-has standardized PET evaluation in MM. However, the prognostic value of IMPeTUs score remains unknown.

METHODS

A total of 58 patients with newly diagnosed multiple myeloma (NDMM) who underwent both [18F]FDG-PET/MRI and PET/CT examinations at diagnosis were enrolled (ChiCTR1900022597). All patients completed a 42-month follow-up. The prognostic value of the PET/MRI (or PET/CT) IMPeTUs score in predicting progression-free (PFS) and overall (OS) survival was compared with that of individual laboratory parameters and the maximum standardized uptake value (SUVmax). Kaplan-Meier method was used for survival analysis. Univariate and multivariate analyses of prognostic factors were conducted using Cox regression.

RESULTS

ROC curves demonstrated that the area under the curve for the PET/MRI IMPeTUs score was 0.760, exceeding that of the PET/CT IMPeTUs score (0.711), PET/CT BM SUVmax (0.649), PET/MRI BM SUVmax (0.575), bone marrow plasma cells (0.500), and β2-microglobulin (0.501). Univariate analysis and Kaplan-Meier analysis showed that a PET/MRI IMPeTUs score ≥ 13 and PET/CT IMPeTUs score ≥ 10 were significantly associated with worse PFS. Cox multivariate analysis showed that a PET/MRI IMPeTUs score ≥ 13 was an independent risk factor for PFS.

CONCLUSION

IMPeTUs standardized [18F]FDG-PET/MRI and PET/CT readings in MM. The IMPeTUs score is crucial for predicting MM prognosis, performing better than SUVmax and clinical indicators.

CLINICAL TRIAL REGISTRATION

ChiCTR1900022597, Registered on 18 April 2019.

Diagnostic Innovations: Advances in imaging techniques for diagnosis and follow-up of multiple myeloma

Introduction

The International Myeloma Working Group (IMWG) defines myeloma related bone disease (MBD) as a diagnostic criterion for symptomatic multiple myeloma (MM) as the presence of osteolytic lesions ≥ 5 mm or more than one focal lesion (FL) ≥ 5 mm by magnetic resonance imaging (MRI). Whole-body low-dose CT (WBLDCT) is recommended as the first-choice imaging technique for the diagnosis of MBD with 18F-fluorodeoxyglucose-positron emission tomography/CT (18F-FDG-PET/CT) being considered a possible alternative at staging, whereas use of MRI studies is recommended in cases without myeloma-defining events (MDEs) in order to exclude the presence of FLs. Furthermore, use of 18F-FDG-PET/CT is recommended in response assessment, to be integrated with hematologic response and bone marrow minimal residual disease (MRD).

Areas covered

In this paper, we review novel functional imaging techniques in MM, particularly focusing on their advantages, limits, applications and comparisons with 18F-FDG-PET/CT or other standardized imaging techniques.

Conclusions

Combining both morphological and functional imaging, 18F-FDG-PET/CT is currently considered a standard imaging technique in MM for staging (despite false positive or negative results) and response assessment. The introduction of novel functional imaging techniques, as whole-body diffusion-weighted magnetic resonance imaging (WB-DWI-MRI), or novel PET tracers might be useful in overcoming these limits. Future studies will give more information on the complementarity of these imaging techniques or whether one of them might become a new gold standard in MM.

The Importance of 18 F-FDG PET/CT in a Rare Case of Multiple Myeloma Presenting With Nasal Plasmacytoma

ABSTRACT

Nasopharyngeal plasmacytoma is a rare presentation of multiple myeloma. We emphasize the importance of imaging by presenting the 18 F-FDG PET/CT findings of a patient with nasopharyngeal plasmacytoma and lytic hypermetabolic bone lesions.

EANM guidelines on the use of [18F]FDG PET/CT in diagnosis, staging, prognostication, therapy assessment, and restaging of plasma cell disorders

We provide updated guidance and standards for the indication, acquisition, and interpretation of [18F]FDG PET/CT for plasma cell disorders. Procedures and characteristics are reported and different scenarios for the clinical use of [18F]FDG PET/CT are discussed. This document provides clinicians and technicians with the best available evidence to support the implementation of [18F]FDG PET/CT imaging in routine practice and future research.

Clinical value of 18F-FDG PET/CT in patients with newly diagnosed acute leukemia

PURPOSE

To explore the correlation between semi-quantitative parameters of 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography/computed tomography (PET/CT) scans findings and the clinical features of patients with acute leukemia (AL), as well as to evaluate the clinical utility of 18F-FDG PET/CT in the management of AL.

METHODS

A retrospective study was conducted with 44 patients newly diagnosed with acute leukemia (AL) at Zhongnan Hospital of Wuhan University between January 2019 and August 2024.

RESULTS

Multivariate analysis revealed that age at diagnosis of AL (odds ratio [OR]: 0.888, P < 0.01) and percentage of blasts in the peripheral blood (PB) (OR: 1.061, P < 0.05) were independent predictors of the appearance of active extramedullary disease (EMD). Kaplan-Meier survival analysis for patients with EMD(+) indicated that those with organ infiltration beyond the lymph nodes experienced markedly reduced overall survival (OS) compared to those without such infiltration (157 days and 806 days, respectively). Furthermore, in the AL subgroup with EMD, the ratio of the maximum standardized uptake value (SUVmax) in the bone marrow (BM) to SUVmax of the liver emerged as an independent prognostic factor for OS (Hazard ratio [HR]: 2.372; 95% confidence interval [CI]: 1.079-5.214, P < 0.05).

CONCLUSION

18F-FDG PET/CT offers the benefits of being non-invasive and highly sensitive for the thorough evaluation of disease status in patients newly diagnosed with AL. Furthermore, the SUVmax BM/liver ratio is of significant clinical importance for prognosticating outcomes in patients with AL presenting EMD.

New PET Tracers for Symptomatic Myeloma

Multiple myeloma (MM) is a hematologic malignancy characterized by the clonal proliferation of plasma cells within the bone marrow. Accurate staging and monitoring of disease progression are crucial for effective management. PET imaging has emerged as a powerful tool in the diagnosis and management of MM, with radiotracers like 18F-fluorodeoxyglucose and novel agents playing a pivotal role. This review explores the current state of PET imaging in multiple myeloma, focusing on its role in initial staging, response assessment, and prognosis prediction, with an emphasis on recent advancements.

Symptomatic Myeloma: PET, Whole-Body MR Imaging with Diffusion-Weighted Imaging or Both

According to international guidelines, patients with suspected myeloma should primarily undergo low-dose whole-body computed tomography (CT) for diagnostic purposes. To optimize sensitivity and specificity and enable treatment response assessment, whole-body MR (WB-MR) imaging should include diffusion-weighted imaging with apparent diffusion coefficient maps and T1-weighted Dixon sequences with bone marrow Fat Fraction Quantification. At baseline WB-MR imaging shows greater sensitivity for the detecting focal lesions and diffuse bone marrow infiltration pattern than 18F-fluorodeoxyglucose PET-CT, which is considered of choice for evaluating response to treatment and minimal residual disease and imaging of extramedullary disease.

Comparative Study of Metabolic Tumor Volume in Multiple Myeloma and Related Plasma Cell Dyscrasias: 11C-Acetate PET vs. 18F-FDG PET

Introduction Accurate diagnosis of multiple myeloma (MM) and related disorders depends on imaging studies for lesion detection, which is crucial for treatment planning. The 18F-fluorodeoxyglucose (FDG) PET imaging system is well-established, with high sensitivity and specificity in identifying myeloma lesions. Additionally, 11C-acetate serves as an effective radiotracer for detecting MM lesions. Metabolic tumor volume (MTV) measured with 18F-FDG PET has been suggested as a prognostic factor in MM patients. This study aimed to compare the feasibility of measuring MTV in patients with myeloma-related diseases using 11C-acetate or 18F-FDG PET/CT. Methods We retrospectively reviewed six patients with MM - three with symptomatic MM and three with smoldering MM - and one patient with a myeloma-related disorder, all of whom underwent both 11C-acetate and 18F-FDG PET/CT scans. Using a dedicated workstation (PET-STAT; AdIn Research, Inc., Tokyo, Japan) equipped with a standardized uptake value (SUV)-based automated contouring program, we calculated the SUV for MTV. Bone areas with an SUV above thresholds of 2.0 or 2.5 were grouped accordingly. Results MTV detection in the whole body was significantly higher with 11C-acetate compared to 18F-FDG at both thresholds. For the 2.5 threshold, MTV was 129 ± 109 mL versus 3.93 ± 9.38 mL (p = 0.016), and for the 2.0 threshold, it was 316 ± 221 mL versus 12.1 ± 23.7 mL (p = 0.016). Conclusions MTV measurements were significantly higher in PET/CT using 11C-acetate compared to 18F-FDG. This finding highlights the potential superiority of 11C-acetate over 18F-FDG for assessing the MTV of lesions in patients with MM.

Positron Emission Tomography/Computed Tomography Transformation of Oncology: Multiple Myeloma

This article provides a comprehensive review of the role of 2-deoxy-2-[18F]fluoro-d-glucose (18F FDG) positron emission tomography/computed tomography (PET/CT) in multiple myeloma (MM) and related plasma cell disorders. MM is a hematologic malignancy characterized by the neoplastic proliferation of plasma cells. 18F FDG PET/CT integrates metabolic and anatomic information, allowing for accurate localization of metabolically active disease. The article discusses the use of 18F FDG PET/CT in initial diagnosis, staging, prognostication, and assessing treatment response. Additionally, it provides valuable insights into the novel imaging targets including chemokine receptor C-X-C motif 4 and CD38.

The added diagnostic value of 18 F-FDG PET/CT radiomic analysis in multiple myeloma patients with negative visual analysis

PURPOSE

A small number of patients diagnosed with multiple myeloma (MM) by bone marrow aspiration reported as being disease-free on 18 F-FDG PET/CT. We aim to evaluate the diagnostic value of radiomics approach in patients with MM who were negative by visual analysis.

MATERIALS AND METHODS

Thirty-three patients judged negative by visual analysis were assigned to the MM group. Contemporaneous 31 disease-free patients served as the control group. 70% of the whole data set was used as training set (23 from MM group and 22 from control group) and 30% as testing set (10 from MM group and 9 from control group). Axial skeleton volumes were automatically segmented and high-dimensional imaging features were extracted from PET and CT. The unsupervised machine learning method was used to filter and reduce the dimensions of the extracted features. Random forest was used to construct the prediction model and then validated with 10-fold cross-validation and evaluated on the independent testing set.

RESULTS

One thousand seven hundred two quantitative features were extracted from PET and CT. Of those, three first-order and one high-order imaging features were uncorrelated. With the cross-validation on the training group, the sensitivity, specificity, accuracy and area under the curve of random forest were 0.850, 0.792, 0.818 and 0.894, respectively. On the independent testing set, the accuracy of the model was 0.850 and the area under the curve was 0.909.

CONCLUSION

Radiomic analysis based on 18 F-FDG PET/CT using machine learning model provides a quantitative, objective and efficient mechanism for diagnosing patients with MM who were negative by visual analysis.

The role of conventional and novel PET radiotracers in assessment of myeloma bone disease

Over 80 % of patients with multiple myeloma (MM) experience osteolytic bone lesions, primarily due to an imbalanced interaction between osteoclasts and osteoblasts. This imbalance can lead to several adverse outcomes such as pain, fractures, limited mobility, and neurological impairments. Myeloma bone disease (MBD) raises the expense of management in addition to being a major source of disability and morbidity in myeloma patients. Whole-body x-ray radiography was the gold standard imaging modality for detecting lytic lesions. Osteolytic lesions are difficult to identify at an earlier stage on X-ray since the lesions do not manifest themselves on conventional radiographs until at least 30 % to 50 % of the bone mass has been destroyed. Hence, early diagnosis of osteolytic lesions necessitates the utilization of more complex and advanced imaging modalities, such as PET. One of the PET radiotracers that has been frequently investigated in MM is 18F-FDG, which has demonstrated a high level of sensitivity and specificity in detecting myeloma lesions. However, 18F-FDG PET/CT has several restrictions, and therefore the novel PET tracers that can overcome the limitations of 18F-FDG PET/CT should be further examined in assessment of MBD. The objective of this review article is to thoroughly examine the significance of both conventional and novel PET radiotracers in the assessment of MBD. The intention is to present the information in a manner that would be easily understood by healthcare professionals from diverse backgrounds, while minimizing the use of complex nuclear medicine terminology.

Clinical utility of PET/MRI in multiple myeloma

Introduction

This study aimed to evaluate the clinical utility of positron emission tomography/magnetic resonance imaging (PET/MRI), especially in comparison with PET/computed tomography (CT), which has been widely used in clinical practice in multiple myeloma.

Method

F-18 fluorodeoxyglucose PET/MRI and PET/ CT studies were done at baseline and when at least a partial response to treatment was achieved. These were done for newly-diagnosed myeloma patients who have not had more than 1 cycle of anti-myeloma treatment, or for relapsed and/or refractory myeloma patients before the start of next line of therapy.

Results

PET/MRI correlated significantly with PET/CT, in terms of number of lesions detected, standardised uptake value (SUVmean and SUVmax, both at baseline and post-treatment. PET/MRI and PET/CT correlated with survival at baseline, but not post-treatment.

Conclusion

In this study, PET/MRI was more sensitive in detecting early disease and disease resolution post-treatment, compared with PET/CT. However, PET/MRI was less sensitive in detecting lesions in the ribs, clavicle and skull.

How do we image patients with multiple myeloma and precursor states?

Advances in morphological and functional imaging have led to superior detection of early bone disease, bone marrow infiltration, paramedullary and extramedullary involvement in multiple myeloma. The two functional imaging modalities that are most widely used and standardized are 18F-fluorodeoxyglucose-Positron emission tomography/computed tomography (FDG PET/CT) and whole-body magnetic resonance imaging with diffusion-weighted imaging (WB DW-MRI). Both prospective and retrospective studies have demonstrated that WB DW-MRI is more sensitive than PET/CT in the detection of baseline tumour burden and to assess response after therapy. In patients with smouldering multiple myeloma, WB DW-MRI is now the preferred imaging modality to rule out two or more unequivocal lesions which would be considered a myeloma-defining event by the updated international myeloma working group (IMWG) criteria. In addition to sensitive detection of baseline tumour burden, both PET/CT and WB DW-MRI have been successfully used for monitoring response to therapy and provide information that is complementary to IMWG response assessment and bone marrow minimal residual disease. In this article, we present 3 vignettes illustrating how we approach the use of modern imaging in the management of patients with multiple myeloma and precursor states, with a specific focus on recent data that have emerged since the publication of the IMWG consensus guideline on imaging. We have utilized data from prospective and retrospective studies to provide a rationale for our approach to imaging in these clinical scenarios and highlighted knowledge gaps requiring future investigation.

Prognostic significance of extramedullary disease (EMD) detected on pre-transplant 18F-FDG PET/CT in patients with multiple myeloma: Results of PIPET-M trial

Background

It is difficult to prognosticate the post-Autologous Stem Cell Transplant (ASCT) responses in multiple myeloma (MM) with the currently available prognostication models. 18F-FDGPET/CT has numerous advantages to prognosticate the post-transplant responses by assessing extramedullary disease (EMD) in addition to the extent of active disease. We aimed at identifying the prognostic value of EMD in predicting progression-free survival (PFS) and overall survival (OS).

Methods

This is a single centre prospective study from western India during a study period of 2014-2022 (with a median follow-up of patients of 6 years). All ASCT patients underwent 18F-FDG-PET/CT as part of pre-transplant workup. The conditioning and treatment protocols were not modified based on PET/CT findings. EMD on PET/CT was correlated with pre-transplant biochemical markers and post-ASCT survival/ progression (as defined by revised IMWG criteria). Statistical analysis was done using SPSS ver. 20.

Results

Patients with pre-ASCT EMD had a hazard-ratio for post-transplant all-cause mortality of 5.46 (p-0.045). Pre-transplant β2M and LDH were significantly higher in patients with EMD (p-0.036). The 6-year median OS in patients with and without EMD were 57.1%, and 80.6% respectively. Kaplan-Meier analysis showed poorer OS in patients with EMD χ2 (1-0.496, p-0.481). There was no significant difference in clinical or biochemical EFS among patients with EMD.

Conclusion

EMD detected on 18F-FDG-PET/CT has a higher hazard for mortality and is significantly correlated with pre-transplant higher β2M and LDH levels. Thus, EMD by pre-transplant 18F-FDG-PET/CT has a significant prognostic role.

New Developments in Myeloma Treatment and Response Assessment

Recent innovative strategies have dramatically redefined the therapeutic landscape for treating multiple myeloma patients. In particular, the development and application of immunotherapy and high-dose therapy have demonstrated high response rates and have prolonged remission duration. Over the past decade, new morphologic or hybrid imaging techniques have gradually replaced conventional skeletal surveys. PET/CT using 18F-FDG is a powerful imaging tool for the workup at diagnosis and for therapeutic evaluation allowing medullary and extramedullary assessment. The independent negative prognostic value for progression-free and overall survival derived from baseline PET-derived parameters such as the presence of extramedullary disease or paramedullary disease, as well as the number of focal bone lesions and SUVmax, has been reported in several large prospective studies. During therapeutic evaluation, 18F-FDG PET/CT is considered the reference imaging technique because it can be performed much earlier than MRI, which lacks specificity. Persistence of significant abnormal 18F-FDG uptake after therapy is an independent negative prognostic factor, and 18F-FDG PET/CT and medullary flow cytometry are complementary tools for detecting minimal residual disease before maintenance therapy. The definition of a PET metabolic complete response has recently been standardized and the interpretation criteria harmonized. The development of advanced PET analysis and radiomics using machine learning, as well as hybrid imaging with PET/MRI, offers new perspectives for multiple myeloma imaging. Most recently, innovative radiopharmaceuticals such as C-X-C chemokine receptor type 4-targeted small molecules and anti-CD38 radiolabeled antibodies have shown promising results for tumor phenotype imaging and as potential theranostics.

The relationship between immunohistochemical parameters, bone marrow fibrosis and bone marrow 18F-FDG uptake in multiple myeloma patients undergoing PET/CT examination

PURPOSE

The aim of this study was to determine the power of the SUVmax value obtained from 18F-FDG PET/CT in multiple myeloma (MM) patients to be able to predict immunophenotype characteristics (CD20, CD44, CD56, CD117, CD138 antigen expressions), bone marrow fibrosis, cyclin D1 oncogene, and M-protein subtypes which play a role in diagnosis-treatment and prognosis of the disease.

MATERIAL AND METHOD

The study included 54 patients with multiple myeloma who underwent PET/CT for initial staging and bone marrow biopsy. The relationship was examined in these patients between the SUVmax value measured from the iliac bone region and the immunohistochemical and bone marrow fibrosis data of the biopsy taken from the iliac bone. The Mann Whitney U test was used in the comparisons of dependent paired groups, and the Kruskal Wallis H test in the comparisons of three or more groups.

RESULTS

The median SUVmax value was 4.5 (1.9-15.6) in patients with CD117 antigen positivity, which was statistically significantly higher than the value in the patients with CD117 negativity (p = 0.031). When patient grouping was made according to the reticulin level; we found that the median SUVmax value was 4.9 (3.0-14.8) in the group with increased fibrosis and 3.6 (1.6-15.6) in the group with low fibrosis. The median SUVmax was statistically significantly higher in the group with increased fibrosis compared to the group with low fibrosis (p = 0.004). No statistically significant difference was determined in the comparisons of the SUVmax values when the patients were grouped according to the immunoglobulin heavy chain and light chain, CD20, CD44, CD56, and cyclin D1 characteristics (p > 0.05).

CONCLUSION

In MM patients who underwent PET/CT for initial staging, significant relationships were determined between FDG uptake in the bone marrow (SUVmax) and CD117 antigen and bone marrow fibrosis, which is an important prognostic factor. Higher SUVmax values were determined in the bone marrow of patients with increased fibrosis and CD117 positivity.

Breaking through Multiple Myeloma: A Paradigm for a Comprehensive Tumor Ecosystem Targeting

Multiple myeloma (MM) is a cancerous condition characterized by the proliferation of plasma cells within the hematopoietic marrow, resulting in multiple osteolytic lesions. MM patients typically experience bone pain, kidney damage, fatigue due to anemia, and infections. Historically, MM was an incurable disease with a life expectancy of around three years after diagnosis. However, over the past two decades, the development of novel therapeutics has significantly improved patient outcomes, including response to treatment, remission duration, quality of life, and overall survival. These advancements include thalidomide and its derivatives, lenalidomide and pomalidomide, which exhibit diverse mechanisms of action against the plasma cell clone. Additionally, proteasome inhibitors such as bortezomib, ixazomib, and carfilzomib disrupt protein degradation, proving specifically toxic to cancerous plasma cells. Recent advancements also involve monoclonal antibodies targeting surface antigens, such as elotuzumab (anti-CS1) and daratumumab (anti-CD38), bispecific t-cell engagers such as teclistamab (anti-BCMA/CD3) and Chimeric antigen receptor T (CAR-T)-based strategies, with a growing focus on drugs that exhibit increasingly targeted action against neoplastic plasma cells and relevant effects on the tumor microenvironment.

Minimal Residual Disease in Multiple Myeloma: Past, Present, and Future

Responses to treatment have improved over the last decades for patients with multiple myeloma. This is a consequence of the introduction of new drugs that have been successfully combined in different clinical contexts: newly diagnosed, transplant-eligible or ineligible patients, as well as in the relapsed/refractory setting. However, a great proportion of patients continue to relapse, even those achieving complete response, which underlines the need for updated response criteria. In 2014, the international myeloma working group established new levels of response, prompting the evaluation of minimal residual disease (MRD) for those patients already in complete or stringent complete response as defined by conventional serological assessments: the absence of tumor plasma cells in 100,000 total cells or more define molecular and immunophenotypic responses by next-generation sequencing and flow cytometry, respectively. In this review, we describe all the potential methods that may be used for MRD detection based on the evidence found in the literature, paying special attention to their advantages and pitfalls from a critical perspective.

Initial study on an expert system for spine diseases screening using inertial measurement unit

In recent times, widely understood spine diseases have advanced to one of the most urgetn problems where quick diagnosis and treatment are needed. To diagnose its specifics (e.g. to decide whether this is a scoliosis or sagittal imbalance) and assess its extend, various kind of imaging diagnostic methods (such as X-Ray, CT, MRI scan or ST) are used. However, despite their common use, some may be regarded as (to a level) invasive methods and there are cases where there are contraindications to using them. Besides, which is even more of a problem, these are very expensive methods and whilst their use for pure diagnostic purposes is absolutely valid, then due to their cost, they cannot rather be considered as tools which would be equally valid for bad posture screening programs purposes. This paper provides an initial evaluation of the alternative approach to the spine diseases diagnostic/screening using inertial measurement unit and we propose policy-based computing as the core for the inference systems. Although the methodology presented herein is potentially applicable to a variety of spine diseases, in the nearest future we will focus specifically on sagittal imbalance detection.

Integrated analysis of next generation sequencing minimal residual disease (MRD) and PET scan in transplant eligible myeloma patients

Minimal residual disease (MRD) assays allow response assessment in patients with multiple myeloma (MM), and negativity is associated with improved survival outcomes. The role of highly sensitive next generation sequencing (NGS) MRD in combination with functional imaging remains to be validated. We performed a retrospective analysis on MM patients who underwent frontline autologous stem cell transplant (ASCT). Patients were evaluated at day 100 post-ASCT with NGS-MRD and positron emission tomography (PET-CT). Patients with ≥ 2 MRD measurements were included in a secondary analysis for sequential measurements. 186 patients were included. At day 100, 45 (24.2%) patients achieved MRD negativity at a sensitivity threshold of 10-6. MRD negativity was the most predictive factor for longer time to next treatment (TTNT). Negativity rates did not differ according to MM subtype, R-ISS Stage nor cytogenetic risk. PET-CT and MRD had poor agreement, with high rates of PET-CT negativity in MRD-positive patients. Patients with sustained MRD negativity had longer TTNT, regardless of baseline risk characteristics. Our results show that the ability to measure deeper and sustainable responses distinguishes patients with better outcomes. Achieving MRD negativity was the strongest prognostic marker and could help guide therapy-related decisions and serve as a response marker for clinical trials.

FDG-PET/CT and new radiopharmaceuticals in patients with multiple myeloma

Multiple myeloma is a monoclonal gammopathy, a clonal proliferative disorder of plasma cells that produces a protein called M or myeloma protein in the bone marrow, usually IgG or IgA. It accounts for 1% in the general cancer statistics and represents 10% of all hematologic tumours, with a cumulative incidence in Spain of about 5/100,000/year. The incidence increases with age, so that 50% of cases are diagnosed in patients over 75 years of age, being infrequent in the population under 40 years of age. This publication details the indications of FDG PET/CT for the staging and response assessment in patients with MM, accepted by the international working group on myeloma, as well as new molecular imaging radiopharmaceuticals with potential value for personalised medicine.

Whole body imaging in musculoskeletal oncology: when, why, and how

The use of whole-body imaging has become increasingly popular in oncology due to the possibility of evaluating total tumor burden with a single imaging study. This is particularly helpful in cases of widespread disease where dedicated regional imaging would make the evaluation more expensive, time consuming, and prone to more risks. Different techniques can be used, including whole-body MRI, whole-body CT, and PET-CT. Common indications include surveillance of cancer predisposing syndromes, evaluation of osseous metastases and clonal plasma cell disorders such as multiple myeloma, and evaluation of soft tissue lesions, including peripheral nerve sheath tumors. This review focuses on advanced whole-body imaging techniques and their main uses in musculoskeletal oncology.

Prognostic value of 18F-fluorodeoxyglucose positron emission tomography/computed tomography at diagnosis in untreated multiple myeloma patients: a systematic review and meta-analysis

Multiple myeloma is a clonal B-lymphocyte tumor of terminally differentiated plasma cells. ¹⁸F-FDG PET/CT can provide valuable data for the diagnosis, restaging, and evaluate prognosis of multiple myeloma (MM). This meta-analysis aimed to evaluate the prognostic value of pre-treatment ¹⁸F-FDG PET/CT at diagnosis in MM patients. Related researches came from Embase, PubMed, and Cochrane Library databases through a systematic search, and the last one was updated on April 26, 2021. Cochran Q test and I-squared statistics were used to test for heterogeneity among the studies analyzed. The fixed model and random model were used to combine results when appropriate. Stata 12.0 was used to perform statistical analysis, and p < 0.05 was considered statistically significant. A total of 16 articles with 2589 patients were included in this study. Our results indicated PET/CT has an excellent prognostic role in MM, that higher SUV_max, more FL and EMD were associated with poor OS and PFS. SUVmax: OS (HR 1.89, 95% CI 1.47-2.44), PFS (HR 1.34, 95% CI 1.18-1.51); Fl: OS (HR 2.65, 95% CI 1.83-3.79), PFS (HR 1.61, 95% CI 1.40-1.86); EMD: OS (HR 2.11, 95% CI 1.41-3.16), PFS (HR 2.18, 95% CI 1.69-2.81). Furthermore, similar results were observed in most subgroup analyzes. Conclusion Pre-treatment ¹⁸F-FDG PET/CT examination has prognostic value for myeloma patients and has guiding significance for clinical treatment.

Clinical impact of spine magnetic resonance imaging as a valuable prognostic tool for patients with multiple myeloma: a retrospective study

Background

This study investigated the prognostic impact of spine magnetic resonance imaging (MRI) in patients newly diagnosed with multiple myeloma (MM).

Methods

We retrospectively evaluated 214 patients who were newly diagnosed with MM between March 2015 and December 2019. The patients were classified into five different infiltration patterns based on spine MRI as follows: (1) normal appearance, (2) focal, (3) diffuse, (4) combined focal and diffuse infiltration, and (5) “salt-and-pepper.”

Results

Forty patients (18.7%) showed a normal appearance, whereas focal, diffuse, combined focal and diffuse infiltration, and “salt-and-pepper” patterns were identified in 68 (31.8%), 40 (18.7%), 52 (24.3%), and 14 patients (6.5%), respectively. The patients with normal and “salt-and-pepper” patterns were younger than patients with other patterns (median age, 61.6 vs. 66.8 years; p=0.001). Moreover, 63% and 59.3% of patients with normal and “salt-and-pepper” patterns were scored International Staging System (ISS) stage I and revised ISS (R-ISS) stage I, respectively, whereas only 12.5% of patients with other patterns were scored ISS stage I and R-ISS stage I. Patients with normal and “salt-and-pepper” patterns had a better prognosis than those with other patterns, whereas relapse and death rates were significantly higher in patients with focal, diffuse, and combined MRI patterns.

Conclusion

Characteristic MRI findings have a significant prognostic value for long-term survival in patients newly diagnosed with MM. In particular, focal, diffuse, and combined focal and diffuse infiltration patterns are unfavorable prognostic factors.

Imaging CXCR4 receptors expression for staging multiple myeloma by using 68Ga-Pentixafor PET/CT: comparison with 18F-FDG PET/CT

OBJECTIVES

68Ga-Pentixafor positron emission tomography (PET) imaging targets CXCR4 expression which is overexpressed in multiple myeloma (MM). In this study, we evaluated the diagnostic utility of 68Ga-Pentixafor PET/CT for imaging CXCR4 expression in MM and compared results with 18F-fluorodeoxyglucose (18F-FDG) PET/CT.

METHODS

34 (21M; 13F; median age = 57.5 years) treatment naive multiple myeloma patients were recruited. All the patients underwent 18F-FDG PET/CT and 68Ga-Pentixafor PET/CT imaging. Freshly prepared 68Ga-Pentixafor (148-185 MBq) was injected intravenously and whole-body PET/CT (low-dose CT) was acquired at 1 h post-injection. The pattern of uptake (diffuse, focal or mixed) and the mean SUVmax value of all the lesions (when lesions were ≤5) or of the five most tracer avid lesions (when lesions was >5) were evaluated. Tumor to background ratio (TBRmax) was calculated for both the tracers. Durie Salmon plus staging (DSPS) was used for disease staging on PET and the results were compared with International staging system (ISS).

RESULTS

68Ga-Pentixafor PET/CT showed higher disease extent than seen on 18F-FDG PET/CT in 23/34 patients (68.0%), lesser disease extent in 2/34 (6%) and similar disease extent in 9/34 (26%) patients. Significantly (p < 0.001) higher TBRmax values (5.7; IQR 8.8) were observed on 68Ga-Pentixafor PET/CT as compared to 18F-FDG PET/CT values (2.9; IQR = 4.0). Both the techniques detected extramedullary lesions in six patients. On the other hand, 68Ga-Pentixafor detected medullary lesions in five, whereas, 18F-FDG PET in three patients. Further, only 68Ga-Pentixafor TBRmax correlated significantly (ρ = 0.421; 0.013) with bone marrow plasma cell percentage. 68Ga-Pentixafor PET upstaged more number (9/29) of patients as compared to (4/29) 18F-FDG PET imaging. On the other hand, 18F-FDG PET down-staged 9/29, whereas 68Ga-Pentixafor PET downstaged only 3/29 patients.

CONCLUSION

68Ga-Pentixafor PET/CT evaluated the whole-body disease burden of CXCR4 receptors non-invasively which is not possible by tissue sampling methods. This novel PET tracer has also implication for disease staging. Dual 68Ga-Pentixafor/18F-FDG PET/CT imaging may help in determining the tumor heterogeneity in MM.

ADVANCES IN KNOWLEDGE

This CXCR4 targeting PET tracer has a promising role in the development of CXCR4 targeting theranostics and also for response assessment to these therapies including the conventional treatment.

18F-FDG Versus Non-FDG PET Tracers in Multiple Myeloma

Multiple myeloma (MM) accounts for 0.9% of cancer diagnoses, and incidence and mortality rate have increased in previous years. 18F-fluorodeoxyglucose (FDG) PET-computed tomography (CT) is an established modality for MM evaluation. MR imaging is helpful where 18F-FDG PET-CT is lacking. To standardize PET reporting, methods like Italian Myeloma Criteria for PET Use and Deauville criteria have been studied. Tracers like 11C-acetate and 11C-choline/18F-fluoromethylcholine (FCH) have shown higher sensitivity and detected more focal lesions and diffuse involvement than 18F-FDG PET-CT. 18F-FCH showed higher maximum standardized uptake value than 18FDG. 11C-methionine appears to be the best radiopharmaceutical, apart from 18F-FDG, for evaluating MM.

Contribution of positron emission tomography/magnetic resonance imaging in musculoskeletal malignancies

Positron emission tomography/computed tomography (PET/CT) is a promising hybrid imaging technique for evaluating musculoskeletal malignancies. Both technologies, independently are useful for evaluating this type of tumors. PET/MR has great potential combining metabolic and functional imaging PET with soft tissue contrast and multiparametric sequences of MR. In this paper we review the existing literature and discuss the different protocols, new available radiotracers to conclude with the scarce evidence available the most useful/probable indications of the PET MR for the for musculoskeletal malignancies.

18 F-FDG PET/CT and MRI in the Management of Multiple Myeloma: A Comparative Review

During the last two decades, the imaging landscape of multiple myeloma (MM) has evolved with whole-body imaging techniques such as fluorodeoxyglucose positron emission tomography-computed tomography (18F-FDG PET/CT) and MRI replacing X-ray skeletal survey. Both imaging modalities have high diagnostic performance at the initial diagnosis of MM and are key players in the identification of patients needing treatment. Diffusion-weighted MRI has a high sensitivity for bone involvement, while 18F-FDG PET/CT baseline parameters carry a strong prognostic value. The advent of more efficient therapeutics, such as immunomodulatory drugs and proteasome inhibitors, has called for the use of sensitive imaging techniques for monitoring response to treatment. Diffusion-weighted MRI could improve the specificity of MRI for tumor response evaluation, but questions remain regarding its role as a prognostic factor. Performed at key time points of treatment in newly diagnosed MM patients, 18F-FDG PET/CT showed a strong association with relapse risk and survival. The deployment of minimal residual disease detection at the cellular or the molecular level may raise questions on the role of these imaging techniques, which will be addressed. This review summarizes and outlines the specificities and respective roles of MRI and 18F-FDG PET/CT in the management of MM.

Modern radiographic imaging in multiple myeloma, what is the minimum requirement?

Imaging innovations offer useful techniques applicable to many oncology specialties. Treatment advances in the field of multiple myeloma (MM) have increased the need for accurate diagnosis, particularly in the bone marrow, which is an essential component in myeloma-defining criteria. Modern imaging identifies osteolytic lesions, distinguishes solitary plasmacytoma from MM, and evaluates the presence of extramedullary disease. Furthermore, imaging is increasingly valuable in post-treatment response assessment. Detection of minimal residual disease after therapy carries prognostic implications and influences subsequent treatment planning. Whole-body low-dose Computed Tomography is now recommended over the conventional skeletal survey, and more sophisticated functional imaging methods, such as ¹⁸F-Fluorodeoxyglucose Positron Emission Tomography , and diffusion-weighted Magnetic Resonance Imaging are proving effective in the assessment and monitoring of MM disease. This review focuses on understanding indications and advantages of these imaging modalities for diagnosing and managing myeloma.

Diagnosis and Management of Multiple Myeloma: A Review

IMPORTANCE

Multiple myeloma is a hematologic malignancy characterized by presence of abnormal clonal plasma cells in the bone marrow, with potential for uncontrolled growth causing destructive bone lesions, kidney injury, anemia, and hypercalcemia. Multiple myeloma is diagnosed in an estimated 34 920 people in the US and in approximately 588 161 people worldwide each year.

OBSERVATIONS

Among patients with multiple myeloma, approximately 73% have anemia, 79% have osteolytic bone disease, and 19% have acute kidney injury at the time of presentation. Evaluation of patients with possible multiple myeloma includes measurement of hemoglobin, serum creatinine, serum calcium, and serum free light chain levels; serum protein electrophoresis with immunofixation; 24-hour urine protein electrophoresis; and full-body skeletal imaging with computed tomography, positron emission tomography, or magnetic resonance imaging. The Revised International Staging System combines data from the serum biomarkers β2 microglobulin, albumin, and lactate dehydrogenase in conjunction with malignant plasma cell genomic features found on fluorescence in situ hybridization-t(4;14), del(17p), and t(14;16)-to assess estimated progression-free survival and overall survival. At diagnosis, 28% of patients are classified as having Revised International Staging stage I multiple myeloma, and these patients have a median 5-year survival of 82%. Among all patients with multiple myeloma, standard first-line (induction) therapy consists of a combination of an injectable proteasome inhibitor (ie, bortezomib), an oral immunomodulatory agent (ie, lenalidomide), and dexamethasone and is associated with median progression-free survival of 41 months, compared with historical reports of 8.5 months without therapy. This induction therapy combined with autologous hematopoietic stem cell transplantation followed by maintenance lenalidomide is standard of care for eligible patients.

CONCLUSIONS AND RELEVANCE

Approximately 34 920 people in the US and 155 688 people worldwide are diagnosed with multiple myeloma each year. Induction therapy with an injectable proteasome inhibitor, an oral immunomodulatory agent and dexamethasone followed by treatment with autologous hematopoietic stem cell transplantation, and maintenance therapy with lenalidomide are among the treatments considered standard care for eligible patients.

Comparison of [68Ga]-FAPI PET/CT and [18F]-FDG PET/CT in Multiple Myeloma: Clinical Experience

Objective: In this study, we aimed to compare [68Ga]FAPI PET/CT and [18F]FDG PET/CT imaging to detect lesions in multiple myeloma. Methods: A total of 14 patients with multiple myeloma who underwent [68Ga]FAPI PET/CT and [18F]FDG PET/CT imaging were included in this retrospective study. SUVmax values of [68Ga]FAPI and [18F]FDG were compared according to lesion locations. Also, lesion localization ability of both imaging methods was compared on the patient basis. Results: In 4 of 14 patients, [68Ga]FAPI PET/CT and [18F]FDG PET/CT have not detected any bone lesions. In 8 of the remaining 10 patients [18F]FDG PET/CT detected bone lesions but in this group, 6 patients showed more higher SUVmax values than [18F]FDG PET/CT in [68Ga]FAPI PET/CT.In contrast, 2 of 8 patients showed more higher SUVmax values than [68Ga]FAPI PET/CT in [18F]FDG PET/CT. Moreover, [68Ga]FAPI PET/CT detected bone lesions in two patients, which werenot detected by [18F]FDG PET/CT. Also, in five patients, [68Ga]FAPI PET/CT showed more bone lesions in comparison with[18F]FDG PET/CT. Only one patient, [18F]FDG PET/CT showed more bone lesions. Three extramedullary involvements were observed in the following locations: lung, presacral lymph node, and soft tissue mass lateral to the right maxillary sinus. Among these involvements, higher SUVmax values were observed in the lung and presacral lymph node with [68Ga]FAPI compared to [18F]FDG. However, the soft tissue mass showed a higher SUVmax value in [18F]FDG than [68Ga]FAPI. Conclusions: No significant superiority was observed in [68Ga]FAPI PET/CT over [18F]FDG PET/CT in patients with MM. However, [68Ga]FAPI PET/CT can be utilized as a complementary imaging method to [18F]FDG PET/CT in some settings, especially in low-[18F]FDG affinity and inconclusive cases. Considering the favorable aspects of [68Ga]FAPI PET/CT in MM, such as low background activity, absence of non-specific bone marrow, and physiological brain involvement, further studies with a larger sample size should be conducted.

Role of FDG PET in the staging of multiple myeloma

¹⁸F-Fluorodeoxyglucose (FDG) PET has been used for staging of hematologic malignancies for years. In multiple myeloma, this imaging modality can be used in many different scenarios, including initial staging, evaluation of treatment response, and investigation of residual disease or early relapse. FDG PET-CT has excellent diagnostic performance, similar to other advanced imaging modalities such as whole-body CT and MRI, and it is particularly helpful for the assessment of extramedullary disease. It also offers important prognostic information on survival and risk of relapse, both at baseline and after therapy. This review will cover the main applications, advantages, and limitations of FDG PET-CT in multiple myeloma and related clonal plasma cell proliferative disorders, such as smoldering multiple myeloma and plasmacytoma.

Oncologist perspective: role of imaging in myeloma

With major advancements in treatments for multiple myeloma (MM), it is critical that we evaluate our methods for both diagnosing MM and monitoring its progression over time. Imaging methods, such as conventional skeletal x-ray, low-dose whole-body CT, MRI, and PET-CT, provide valuable information that influences our clinical decision-making. In this review, we will evaluate the role of these imaging techniques throughout the MM disease course, from diagnosis to follow-up after therapy, and also provide appropriate recommendations.

[Positron emission tomography/computed tomography (PET/CT) in multiple myeloma]

BACKGROUND

Imaging plays a pivotal role in the management of multiple myeloma (MM). Besides morphological imaging methods, such as whole-body X‑ray, computed tomography (CT) and magnetic resonance imaging (MRI), the hybrid modality positron emission tomography/CT (PET/CT) using the glucose analogue ¹⁸F‑fluorodeoxyglucose (¹⁸F‑FDG) as radiotracer is increasingly used.

OBJECTIVES

Aim of this review article is to outline the major applications of PET/CT in the diagnosis and management of MM, and to provide hints on the reading and interpretation.

MATERIALS AND METHODS

Background knowledge and guideline recommendations on imaging of MM are outlined and complemented by recent study results.

RESULTS

Although ¹⁸F‑FDG PET/CT is not currently considered a standard method for the diagnosis of MM, it is a very powerful diagnostic tool for the detection of medullary and extramedullary disease, a reliable predictor of survival and the most robust modality for treatment response evaluation. Moreover, it plays a significant role in minimal residual disease (MRD) assessment. On the other hand, practical considerations on local availability and costs limit the widespread use of PET/CT. In addition, false-negative and the seldom false-positive results and the heterogeneity of MM presentation inevitably make interpretation of PET/CT images challenging.

CONCLUSIONS

PET/CT has a high value in the diagnosis, prognosis, and assessment of treatment response in patients with MM. Therefore, the role of the modality in the management of the disease is expected to increase in the near future.

Metabolic Volume Measurements in Multiple Myeloma

Multiple myeloma (MM) accounts for 10-15% of all hematologic malignancies, as well as 20% of deaths related to hematologic malignant tumors, predominantly affecting bone and bone marrow. Positron emission tomography/computed tomography with 18F-fluorodeoxyglucose (FDG-PET/CT) is an important method to assess the tumor burden of these patients. It is often challenging to classify the extent of disease involvement in the PET scans for many of these patients because both focal and diffuse bone lesions may coexist, with varying degrees of FDG uptake. Different metrics involving volumetric parameters and texture features have been proposed to objectively assess these images. Here, we review some metabolic parameters that can be extracted from FDG-PET/CT images of MM patients, including technical aspects and predicting MM outcome impact. Metabolic tumor volume (MTV) and total lesion glycolysis (TLG) are volumetric parameters known to be independent predictors of MM outcome. However, they have not been adopted in clinical practice due to the lack of measuring standards. CT-based segmentation allows automated, and therefore reproducible, calculation of bone metabolic metrics in patients with MM, such as maximum, mean and standard deviation of the standardized uptake values (SUV) for the entire skeleton. Intensity of bone involvement (IBI) is a new parameter that also takes advantage of this approach with promising results. Other indirect parameters obtained from FDG-PET/CT images, such as visceral adipose tissue glucose uptake and subcutaneous adipose tissue radiodensity, may also be useful to evaluate the prognosis of MM patients. Furthermore, the use and quantification of new radiotracers can address different metabolic aspects of MM and may have important prognostic implications.

Optimization of whole-body 2-[18F]FDG-PET/MRI imaging protocol for the initial staging of patients with myeloma

OBJECTIVE

To determine the optimal 2-[¹⁸F]FDG-PET/MRI imaging protocol for the initial staging of patients with suspected or confirmed multiple myeloma.

METHODS

Radiologists and nuclear medicine specialists reviewed all PET/MRI exams of 104 patients with a monoclonal gammopathy (MG). The presence of focal and diffuse bone marrow involvement (BMI) was assessed using 4 different image datasets: WB-MRI, PET, WB-PET/MRI, and WB-DCE-PET/MRI. A reference standard was established by a panel review of all baseline and follow-up imaging, and biological and pathological information. The diagnostic performance for each image dataset to detect BMI was evaluated and compared (Fisher's exact test).

RESULTS

Sensitivity, specificity, and accuracy for focal BMI of WB-MRI was 87%, 97%, and 92%; of PET was 78%, 97%, and 95%; of WB-PET/MRI was 93%, 97%, and 95%; and of WB-DCE-PET/MRI was 93%, 97%, and 95%, respectively. WB-PET/MRI and WB-DCE-PET/MRI were statistically superior to PET (p = 0.036) without decreasing specificity. The sensitivity, specificity, and accuracy of WB-MRI for diffuse BMI detection was 91%, 80%, and 85%; of 3DT1-PET was 53%, 89%, and 74%; of WB-PET/MRI was 98%, 66%, and 79%; and of WB-DCE-PET/MRI was 98%, 59%, and 75%, respectively. PET lacked sensitivity compared to all other dataset studies (p < 0.0001). WB-MRI had the best accuracy without reaching statistical significance when compared to the other datasets.

CONCLUSION

The WB-PET/MRI dataset including T1 and T2 Dixon, WB-DWI, and PET images provides optimal diagnostic performance to detect both focal lesions and diffuse BMI, with limited added value of WB-DCE for baseline staging of patients with MG. Key Points • The combination of morphological and functional MRI sequences and metabolic (2-[¹⁸F]FDG-PET) images increases the diagnostic performance of PET/MRI to detect focal bone lesions. • The adjunction of dynamic contrast-enhanced sequences did not improve diagnostic performance.

11C-acetate positron emission tomography is more precise than 18F-fluorodeoxyglucose positron emission tomography in evaluating tumor burden and predicting disease risk of multiple myeloma

The optimal method of tumor burden evaluation in newly diagnosed multiple myeloma (NDMM) is yet to be determined. This study aimed to compare the value of ¹¹C-acetate positron-emission tomography (PET)/computed tomography (CT) (AC-PET and ¹⁸F-fluorodeoxyglucose PET/CT (FDG-PET) in the assessment of tumor burden in NDMM. This study evaluated 64 NDMM patients between February 2015 and July 2018. AC-PET and FDG-PET were used to assess myeloma lesions. The clinical data, imaging results, and their correlations were analyzed. Diffuse bone marrow uptake in AC-PET was significantly correlated with biomarkers for tumor burden, including serum hemoglobin (P = 0.020), M protein (P = 0.054), the percentage of bone marrow plasma cells (P < 0.001), and the Durie–Salmon stage of the disease (P = 0.007). The maximum standard uptake value (SUV_max) of focal lesions and high diffuse bone marrow uptake in AC-PET showed stronger correlations with high-risk disease (P = 0.017, P = 0.013) than those in FDG-PET. Moreover, the presence of diffuse bone marrow uptake, more than ten focal lesions, and an SUV_max of focal lesions of > 6.0 in AC-PET, but not in FDG-PET, predicted a higher probability of disease progression and shorter progression-free survival (P < 0.05). AC-PET outperformed FDG-PET in tumor burden evaluation and disease progression prediction in NDMM.

Comparative Performance of Whole Body MRI and 18F-FDG PET/CT in Evaluation of Response to Treatment of Multiple Myeloma: Meta-analysis and Systematic Review

Background: Traditional approaches for evaluating multiple myeloma (MM) treatment response have low sensitivity for residual disease. Recent studies highlight utility of whole-body MRI or FDG PET/CT in evaluating treatment response, with increasing emphasis on DWI. Objective: This systematic review was conducted to assess the diagnostic accuracy of whole-body MRI and FDG PET/CT for treatment response assessment in MM. Evidence Acquisition: Studies using whole-body MRI or FDG PET/CT to evaluate MM treatment response were identified through search of PubMed and EMBASE databases through June 30, 2021. Pooled sensitivity and specificity for detecting response were calculated by bivariate modeling. Diagnostic performance of whole-body MRI and FDG PET/CT were compared. Subgroup analyses assessed studies comparing both modalities and studies in which whole-body MRI included DWI. Evidence Synthesis: Twelve studies comprising 373 patients were included: six evaluated both modalities, four evaluated whole-body MRI only, and two evaluated FDG PET/CT only; of studies with MRI, five used DWI. Pooled sensitivity and specificity were 87% (95% CI, 75%-93%) and 57% (95% CI, 37%-76%) for whole-body MRI, versus 64% (95% CI, 45%-79%) and 82% (95% CI, 75%-88%) for FDG PET/CT (sensitivity: p = .29; specificity: p = .01). For studies directly comparing the modalities, pooled sensitivity and specificity were 90% (95% CI, 80%-100%) and 56% (95% CI, 44%-68%) for whole-body MRI, versus 66% (95% CI, 47%-85%) and 81% (95% CI, 72%-90%) for FDG PET/CT (sensitivity: p = .18; specificity: p < .001). Sensitivity and specificity were 93% (95% CI, 75%-98%) and 57% (95% CI, 21%-87%) for DWI, versus 74% (95% CI, 60%-85%) and 56% (95% CI, 38%-73%) for whole-body MRI without DWI (sensitivity: p = .27; specificity: p = .99). AUC was 0.84 for whole-body MRI, 0.83 for FDG PET/CT, and 0.92 for DWI. Conclusion: FDG PET/CT had significantly higher specificity, whereas whole-body MRI had higher sensitivity (though non-significant). DWI may contribute to the high sensitivity of whole-body MRI. Clinical Impact: This meta-analysis suggests potential complementary roles of whole-body MRI and FDG PET/CT in MM treatment response assessment. Future studies should explore their combination through PET/MRI.

Improved 18-FDG PET/CT diagnosis of multiple myeloma diffuse disease by radiomics analysis

OBJECTIVES

In multiple myeloma, the diagnosis of diffuse bone marrow infiltration on 18-FDG PET/CT can be challenging. We aimed to develop a PET/CT radiomics-based model that could improve the diagnosis of multiple myeloma diffuse disease on 18-FDG PET/CT.

METHODS

We prospectively performed PET/CT and whole-body diffusion-weighted MRI in 30 newly diagnosed multiple myeloma. MRI was the reference standard for diffuse disease assessment. Twenty patients were randomly assigned to a training set and 10 to an independent test set. Visual analysis of PET/CT was performed by two nuclear medicine physicians. Spine volumes were automatically segmented, and a total of 174 Imaging Biomarker Standardisation Initiative-compliant radiomics features were extracted from PET and CT. Selection of best features was performed with random forest features importance and correlation analysis. Machine-learning algorithms were trained on the selected features with cross-validation and evaluated on the independent test set.

RESULTS

Out of the 30 patients, 18 had established diffuse disease on MRI. The sensitivity, specificity and accuracy of visual analysis were 67, 75 and 70%, respectively, with a moderate kappa coefficient of agreement of 0.6. Five radiomics features were selected. On the training set, random forest classifier reached a sensitivity, specificity and accuracy of 93, 86 and 91%, respectively, with an area under the curve of 0.90 (95% confidence interval, 0.89-0.91). On the independent test set, the model achieved an accuracy of 80%.

CONCLUSIONS

Radiomics analysis of 18-FDG PET/CT images with machine-learning overcame the limitations of visual analysis, providing a highly accurate and more reliable diagnosis of diffuse bone marrow infiltration in multiple myeloma patients.

Prognostic significance of 68Ga-Pentixafor PET/CT in multiple myeloma recurrence: a comparison to 18F-FDG PET/CT and laboratory results

PURPOSE

This study investigates the prognostic value of 68Ga-Pentixafor PET/CT using PET-derived quantitative in multiple myeloma (MM) patients with suspected recurrence in comparison to 18F-FDG PET/CT and clinical data.

METHODS

Twenty-four MM patients with suspicion for relapse who underwent 68Ga-Pentixafor and 18F-FDG PET/CT were retrospectively evaluated. Total bone marrow glycolysis for 18F-FDG (TBMFDG) and total bone marrow uptake for 68Ga-Pentixafor PET/CT (TBMCXCR4) were calculated using whole-body metabolic tumor burden obtained by dedicated software (MIM 7.0.6). The patients were followed for 19-24 months, and the association of PET-derived quantitative data with overall survival (OS) was analyzed.

RESULTS

68Ga-Pentixafor PET/CT was positive in 17 patients, of which 13 were also positive on 18F-FDG PET/CT, whereas 7 patients were negative on both scans. The positive rate of 68Ga-Pentixafor and 18F-FDG PET/CT on a patient-based approach was 70.8% and 54.1%, respectively. 68Ga-Pentixafor positivity was significantly associated with OS (p = 0.009), and 18F-FDG positivity was at the margin of statistical significance (p = 0.056). TBMCXCR4 and TBMFDG were negatively correlated with OS (r = -0.457, p = 0.025 and r = -0.617, p = 0.001, respectively). The OS was negatively correlated with beta-2-microglobulin levels (r = -0.511, p = 0.01) and CRAB score (r = -0.592, p = 0.002) as an indicator of the end-organ disease, which confirmed these results. Serum beta-2-microglobulin levels and CRAB score were also correlated with TBMCXCR4 (r = 0.442, p = 0.039 and r = 0.573, p = 0.003, respectively) and TBMFDG (r = 0.543, p = 0.009 and r = -0.424, p = 0.003, respectively).

CONCLUSION

68Ga-Pentixafor PET/CT positivity is a negative prognostic factor in the survival outcome of MM patients. Complementary 68Ga-Pentixafor PET/CT has the potential to overcome 18F-FDG PET/CT limitations and helps a more precise risk stratification.

Favorable Long-Term Outcomes with Autologous Stem Cell Transplantation for High-Risk Multiple Myeloma Patients with a Positive Result On 18F-FDG PET/CT at Baseline

BACKGROUND

18F-fluorodeoxyglucose positron emission tomography/computed tomography (¹⁸F-FDG PET/CT) is a useful tool for identifying high-risk features in patients with newly diagnosed multiple myeloma (NDMM). This study evaluated the role of autologous stem cell transplantation (ASCT) in patients presenting with positive results on PET/CT scans.

MATERIALS AND METHODS

The medical records of 210 patients who underwent PET/CT at diagnosis were retrospectively reviewed. Eligible patients for transplantation proceeded to upfront ASCT with high-dose chemotherapy (HDT) after induction therapy with novel agents.

RESULTS

The presence of a number of focal lesions (FL) >3 and extramedullary disease (EMD) occurred in 111 and 35 patients, respectively. ASCT was performed in 54 patients. Among patients with FL > 3, those treated with ASCT showed a prolonged 2-year progression-free survival (PFS) and overall survival (OS) rates compared to those not treated with ASCT (PFS, 60.2% vs. 23.5%, P < 0.001; OS, 91.7% vs. 63.6%, P = 0.005). In patients with FL ≤ 3, treatment by ASCT was associated with a higher 2-year PFS rate than no treatment by ASCT (74.0% vs. 54.9%, P = 0.040). The OS of patients treated with ASCT was not significantly longer than that of patients not treated with ASCT (P = 0.115). In multivariate analysis, FL > 3, Revised International Staging System (R-ISS), and upfront ASCT were independent prognostic factors for PFS and OS.

CONCLUSION

Presenting FL > 3 on baseline PET/CT represents a high-risk feature in patients with NDMM. Frontline ASCT with HDT prolonged the survival of patients with FL > 3.

Prognostic Value of FDG-PET/CT Parameters in Patients with Relapse/Refractory Multiple Myeloma before Anti-CD38 Based Therapy

Although anti-CD38 monoclonal antibodies have improved the prognosis of relapsed/refractory multiple myeloma (RRMM), some patients still experience early relapses with poor outcomes. This present study evaluated the predictive value of FDG PET/CT parameters for RRMM prior to initiating anti-CD38 treatment. We included 38 consecutive RRMM patients who underwent a PET/CT scan treated at our institution at relapse. The median PFS was 12.5 months and the median OS was not reached. 42% of the patients had an initial ISS score of 1, 37% of 2, and 21% of 3. The presence of >3 focal lesions (FLs, n = 19) and the ISS score were associated with inferior PFS (p = 0.0036 and p = 0.0026) and OS (p = 0.025 and p = 0.0098). Patients with >3 FLs had a higher initial ISS score (p = 0.028). In multivariable analysis, the ISS score and >3 FLs were independent prognostic factors for PFS (p = 0.010 and p = 0.025 respectively), and combined they individualized a high-risk group with a median PFS and OS of 3.1 months and 8.5 months respectively vs. not reached for the other patients. The presence of >3 FLs on PET was predictive of survival outcomes in patients with RRMM treated using CD38 targeted therapy. Combined with the initial ISS, an ultra-high-risk RRMM population can thus be identified.

Skeletal Survey in Multiple Myeloma: Role of Imaging

Bone disease is the hallmark of multiple myeloma. Skeletal lesions are evaluated to establish the diagnosis, to choose the therapies and also to assess the response to treatments. Due to this, imaging procedures play a key role in the management of multiple myeloma. For decades, conventional radiography has been the standard imaging modality. Subsequently, advances in the treatment of multiple myeloma have increased the need for an accurate evaluation of skeletal disease. The introduction of new high performant imaging tools, such as whole-body lowdose computed tomography, different types of magnetic resonance imaging studies, and 18F-fluorodeoxyglucose positron emission tomography, replaced the conventional radiography. In this review, we analyze the diagnostic potentials, indications of use, and applications of the imaging tools nowadays available. Whole-body low-dose CT should be considered as the imaging modality of choice for the initial assessment of multiple myeloma lytic bone lesions. MRI is the gold-standard for the detection of bone marrow involvement, while PET/CT is the preferred technique in the assessment of response to therapy. Both MRI and PET/CT are able to provide prognostic information.

Clinical Applications of PET/MR Imaging

PET/MR imaging is in routine clinical use and is at least as effective as PET/CT for oncologic and neurologic studies with advantages with certain PET radiopharmaceuticals and applications. In addition, whole body PET/MR imaging substantially reduces radiation dosages compared with PET/CT which is particularly relevant to pediatric and young adult population. For cancer imaging, assessment of hepatic, pelvic, and soft-tissue malignancies may benefit from PET/MR imaging. For neurologic imaging, volumetric brain MR imaging can detect regional volume loss relevant to cognitive impairment and epilepsy. In addition, the single-bed position acquisition enables dynamic brain PET imaging without extending the total study length which has the potential to enhance the diagnostic information from PET.