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

Imaging in multiple myeloma: How? When?

Bone disease is the most frequent feature of multiple myeloma (MM) and represents a marker of end-organ damage; it is used to establish the diagnosis and to dictate the immediate need for therapy. For this reason, imaging plays a significant role in the management of MM patients. Although conventional radiography has traditionally been the standard imaging modality, its low sensitivity in detecting osteolytic lesions and inability to evaluate response to therapy has called for the use of more sophisticated techniques, such as whole-body low-dose computed tomography (WBLDCT), whole-body magnetic resonance imaging, and ¹⁸F-fluorodeoxyglucose-positron emission tomography/computed tomography (PET/CT). In this review, the advantages, indications of use, and applications of the 3 techniques in the management of patients with MM in different settings will be discussed. The European Myeloma Network and the European Society for Medical Oncology guidelines have recommended WBLDCT as the imaging modality of choice for the initial assessment of MM-related lytic bone lesions. Magnetic resonance imaging is the gold-standard imaging modality for detection of bone marrow involvement, whereas PET/CT provides valuable prognostic data and is the preferred technique for assessment of response to therapy. Standardization of most of the techniques is ongoing.

Vertebral Fractures of Unknown Origin: Role of Computed Tomography-Guided Biopsy

Background

We performed a retrospective evaluation of histological and imaging results of patients submitted to computed tomography (CT)-guided biopsy for vertebral fractures (VFs) of unknown etiology to evaluate the pathological causes of fractures and also to observe the diagnostic results of imaging studies available.

Methods

We retrospectively reviewed all the CT-guided vertebral biopsies performed in our institution in the last 2 years, selecting patients with VF of unknown etiology. We reviewed clinical records, imaging studies, and histological examination results. We compared diagnostic performance of the 2 most sensitive imaging modalities for detection of malignancy on the collapsed vertebral body: magnetic resonance imaging (MRI) and positron emission tomography-CT (PET-CT). Anatomopathological results have been considered the gold standard to assess the diagnostic performance of imaging studies. Age stratification has been performed to understand the distribution of different anatomopathological diagnoses in age groups.

Results

Among 282 CT-guided vertebral biopsies, 36 (12.8%) have been performed to diagnose the etiology of VF of unknown origin. In 26/32 (81.3%), the vertebral biopsy was diagnostic: 8 osteopenia, 6 multiple myelomas, 4 osteomyelitis, 2 eosinophilic granuloma, 3 metastases, 1 mastocytosis, 1 Paget's disease, and 1 dysmielopoiesis. In 6 cases, the anatomopathological diagnosis was normal bone structure, most likely excluding malignancy. There were no statistically significance differences between MRI and PET-CT results (P = 1.0000).

Conclusions

Multiple myeloma and osteopenia represent the most frequent causes of this condition in adult patients, while eosinophilic granuloma and osteomyelitis in pediatric patients. Computed tomography-guided biopsy permits one to reach diagnosis in most of cases. Both PET and MRI could be insufficient to discriminate benign from malignant causes of fractures. Computed tomography-guided biopsy is needed when the etiology of fracture remains unclear.

How We Manage Patients with Plasmacytomas

PURPOSE OF REVIEW

To discuss the diagnostic approach, treatment options, and future considerations in the management of plasmacytomas, either solitary or in the context of overt multiple myeloma (MM).

RECENT FINDINGS

Advanced imaging techniques such as whole-body magnetic resonance imaging and positron emission tomography/computerized tomography are essential for the diagnostic workup of solitary plasmacytomas (SP) to rule out the presence of other disease foci. The role of flow cytometry and clonal plasma cell detection is currently under study together with other prognostic factors for the identification of patients with SP at high risk of progression to overt MM. Solitary plasmacytomas are treated effectively with local radiotherapy whereas systemic therapy is required at relapse. Clonal plasma cells that accumulate at extramedullary sites have distinct biological characteristics. Patients with MM and soft tissue involvement have poor outcomes and should be treated as ultra-high risk. A revised definition of SP that distinguishes between true solitary clonal PC accumulations and SP with minimal bone marrow involvement should be considered to guide an appropriate therapeutic and follow-up approach. Future studies should be conducted to determine optimum treatment approaches for patients with MM and paraskeletal or extramedullary disease.

Utility and prognostic value of 18 F-FDG positron emission tomography-computed tomography scans in patients with newly diagnosed multiple myeloma

Positron emission tomography-computed tomography (PET-CT) can identify bony lesions, assess disease burden, and detect extramedullary disease (EMD) in patients with multiple myeloma. We retrospectively reviewed records of patients who underwent PET-CT within 60 days of a new diagnosis (before therapy commenced) to identify the nature and prognostic impact of PET-CT abnormalities. Patients (N = 313) were seen from April 2005 through June 2017. Of the 234 patients (75%) with focal lesions (FLs), 182 (58%) had at least 3 FLs, 38 (12%) had EMD, and 204 (65%) had documented myelomatous lytic lesions. The median maximum standardized uptake value (SUV_max ) for the entire cohort was 5.9 (range 1.5-48.3). Presence of at least 3 FLs and EMD predicted inferior overall survival (OS); median OS was 57.8 months for patients with 3 or more FLs and 103.6 months for patients with fewer than 3 FLs (P = .003). The median OS was 45.5 and 71.8 months for patients with and without EMD, respectively (P = .004). No clear SUV_max cutoff was predictive of progression-free survival or OS. PET-CT is a valuable tool for assessing disease burden and could provide prognostic information about a contemporary cohort of patients with newly diagnosed myeloma who received treatment with novel agents.

Bones in Multiple Myeloma: Imaging and Therapy

F-fluorodeoxyglucose (FDG)-PET/CT, MRI, and other novel imaging modalities in the management of disease in patients with plasma cell dyscrasias. We also review the state of the art in treatment of MM bone disease (MMBD) and the role of bisphosphonates and denosumab, a monoclonal antibody that binds and blocks the activity of receptor activator of nuclear factor-kappa B ligand (RANKL), which was recently approved by the U.S. Food and Drug Administration for MMBD.

Novel biomarkers in multiple myeloma

Significant advancements have been made in the molecular mechanisms of myelomagenesis, diagnostic methods, prognostication, and the treatment options in multiple myeloma (MM) over the last decade. Despite these, MM remains a heterogeneous disease with differing outcomes. As myeloma treatment landscape continues to expand, personalized treatment that provides maximum benefit to a specific patient becomes more important. In the last few years, serum monoclonal proteins including the serum-free light chain assays, imaging, and cytogenetics have been used to predict the outcomes of MM patients receiving different types of therapies. With the development of novel technologies, more sensitive detection of residual disease using flow cytometry and next-generation sequencing has been possible. In addition, liquid biopsies using circulating tumor cells, tumor DNA, and novel immune biomarkers are potentially being investigated. These novel potential biomarkers not only accurately detect the mutational landscape of different cancers compared to standard methods but also serve as prognostic and predictive biomarkers for disease relapse and response to therapy. It is likely that we will be able to offer more targeted and risk-adapted therapeutic approach to patients with MM at different stages of their disease guided by these potential biomarkers.

Whole-Body MR Imaging: The Novel, "Intrinsically Hybrid," Approach to Metastases, Myeloma, Lymphoma, in Bones and Beyond

Whole-body MR imaging (WB-MR imaging) has become a modality of choice for detecting bone metastases in multiple cancers, and bone marrow involvement by multiple myeloma or lymphoma. Combination of anatomic and functional sequences imparts an inherently hybrid dimension to this nonirradiating tool and extends the screening of malignancies outside the skeleton. WB-MR imaging outperforms bone scintigraphy and CT and offers an alternative to PET in many tumors by time of lesion detection and assessment of treatment response. Much work has been done to standardize procedures, optimize sequences, validate indications, confirm preliminary research into new applications, rendering clinical application more user-friendly.

The Role of 18F-FDG PET/CT in Multiple Myeloma Staging according to IMPeTUs: Comparison of the Durie-Salmon Plus and Other Staging Systems

We aimed at comparing the Durie–Salmon Plus (DS Plus) staging system based on Italian Myeloma criteria for PET USe (IMPeTUs) with other two staging systems in predicting prognosis of patients with all stages of newly diagnosed multiple myeloma (MM). A total of 33 MM patients were enrolled in this retrospective study. The variation between the DS Plus classification and Durie–Salmon staging system (DSS) or Revised International Staging System (RISS) classification was assessed. When staged by the DSS, patients in stage I and stage II did not reach the median overall survival (OS), and the median OS was 33 months for stage III (p=0.3621). When staged by the DS Plus, patients in stage I did not reach the median OS of stage I, and the median OS for stages II and III was 38 and nine months, respectively (p=0.0064). When staged by the RISS, patients in stage I did not reach the median OS, and the median OS was 33 and 16 months for stage II and stage III, respectively (p=0.0319). The concordances between two staging systems were 0.07 (DS Plus versus DSS) and 0.37 (DS Plus versus RISS), respectively. Multivariate analysis revealed that DS Plus stage III (HR: 11.539, p=0.021) and the Deauville score of bone marrow ≥4 (HR: 3.487, p=0.031) were independent prognostic factors associated with OS. Both the DS Plus based on IMPeTUs and RISS possessed a better potential in characterizing and stratifying MM patients compared with the DSS. Moreover, DS Plus stage III and the Deauville score of bone marrow ≥4 were reliable prognostic factors in newly diagnosed MM patients.

How I treat the young patient with multiple myeloma

The treatment landscape for multiple myeloma has been transformed by the introduction of novel agents, including immunomodulatory drugs, proteasome inhibitors, and monoclonal antibodies. These have been shown to be more effective and generally better tolerated than conventional chemotherapy, with their introduction into clinical practice leading to improved survival. Furthermore, a better understanding of disease biology, improved diagnostic criteria, and the development of sensitive and specific tools for disease prognostication have contributed to better outcome. Treatment in the younger patient can now be individualized based on host and disease features with enhanced monitoring of response and use of high-sensitivity techniques for evaluating residual disease. The current standard of care has been significantly enhanced by novel agents with a paradigm shift toward optional or delayed autologous stem cell transplant as a reasonable choice in selected patients. Conversely, extended treatment with induction of remission followed by maintenance strategies is now a standard of care, conferring prolonged disease control with more manageable toxicities in both the short and long term, as well as improved quality of life.

Clinical PET/MRI: 2018 Update

OBJECTIVE

The purpose of this article is to provide an update on clinical PET/MRI, including current and developing clinical indications and technical developments.

CONCLUSION

PET/MRI is evolving rapidly, transitioning from a predominant research focus to exciting clinical practice. Key technical obstacles have been overcome, and further technical advances promise to herald significant advancements in image quality. Further optimization of protocols to address challenges posed by this hybrid modality will ensure the long-term success of PET/MRI.

A predicting model of bone marrow malignant infiltration in 18F-FDG PET/CT images with increased diffuse bone marrow FDG uptake

Purpose: To demonstrate the relationship between the etiologies of increased diffuse bone marrow (BM) ¹⁸F-FDG uptake and PET/CT imaging/clinical features, as well as to explore a predicting model of BM malignant infiltration (MI) based on decision tree. Methods: 84 patients with increased diffuse BM uptake were retrospectively enrolled. Their complete case record and PET/CT images were reviewed, with the maximal standardized uptake values of bone marrow (SUVmaxBM) and other imaging/clinical features were noted. At the same time, the differences in imaging/clinical features between bone marrow MI and non-MI groups were compared. The decision tree for predicting MI was established by C5.0 component of SPSS Clementine. Results: In patients with homogenously increased BM uptake, 21 patients had MI resulted from leukemia, lymphoma and small cell lung cancer (SCLC). MI group had higher SUVmaxBM than non-MI group (6.7±3.1 vs 4.2±0.9, p=0.001). However, a considerable proportion of MI patients had similar SUVmaxBM to non-MI patients, which were mainly seen in lymphoplasmacytic lymphoma/Waldenström macroglobulinemia (LPL/WM), chronic myeloid leukemia (CML) and multiple myeloma (MM). There were significant differences in other factors between the two groups. MI patients were highly associated with SUVmaxAP/AX≥1 (the ratio of SUVmaxBM of appendicular skeleton to that of axial skeleton), hepatosplenomegaly, older age and lower rate of fever. The decision tree combining SUVmaxBM, SUVmaxAP/AX, fever and hepatosplenomegaly achieved a sensitivity of 81.0%, a specificity of 98.4% and an accuracy of 94.0% for predicting MI. Conclusion: Increased diffuse BM ¹⁸F-FDG uptake can be attributed to both bone marrow MI and benign etiologies. A decision tree based on C5.0 algorithm, combining PET/CT imaging and clinical features, is of potential use in discriminating BM malignant infiltration from patients with increased diffuse BM uptake.

Diagnostic performance of 18F-FDG PET/CT and whole-body MRI before and early after treatment of multiple myeloma: a prospective comparative study

OBJECTIVE

To determine the diagnostic accuracy of WB-MRI and ¹⁸F-FDG PET/CT in detecting infiltration pattern, disease activity, and response to treatment in patients with multiple myeloma (MM).

MATERIALS AND METHODS

Fifty-six patients with confirmed MM were included in the present study for pre-treatment evaluation. Among these individuals, 22 patients were available for the post-treatment evaluation of response to therapy. All patients were imaged with both WB-MRI and ¹⁸F-FDG PET/CT. All radiographic findings of infiltration pattern, disease activity, and response to therapy were compared. The diagnostic performance of both modalities was estimated using bone marrow aspirate and biopsy as the reference test.

RESULTS

For detection of active myelomatous tissue at diagnosis, WB-MRI achieved higher sensitivity (94%) than ¹⁸F-FDG PET/CT (75%) (p = 0.0039), whereas both modalities achieved the same specificity (80%). For detection of residual myelomatous tissue after treatment, ¹⁸F-FDG PET/CT achieved higher specificity (86%) than WB-MRI (43%) (p = 0.0081), whereas both modalities achieved the same sensitivity (75%).

CONCLUSION

WB-MRI is more sensitive than ¹⁸F-FDG PET/CT in the diagnosis of MM before treatment; however, ¹⁸F-FDG PET/CT is more specific than WB-MRI in detecting residual involvement in treated patients.

Assessment of glucose metabolism and cellular proliferation in multiple myeloma: a first report on combined 18F-FDG and 18F-FLT PET/CT imaging

Background

Despite the significant upgrading in recent years of the role of ¹⁸F-FDG PET/CT in multiple myeloma (MM) diagnostics, there is a still unmet need for myeloma-specific radiotracers. 3′-Deoxy-3′-[¹⁸F]fluorothymidine (¹⁸F-FLT) is the most studied cellular proliferation PET agent, considered a potentially new myeloma functional imaging tracer. The aim of this pilot study was to evaluate ¹⁸F-FLT PET/CT in imaging of MM patients, in the context of its combined use with ¹⁸F-FDG PET/CT.

Results

Eight patients, four suffering from symptomatic MM and four suffering from smoldering MM (SMM), were enrolled in the study. All patients underwent ¹⁸F-FDG PET/CT and ¹⁸F-FLT PET/CT imaging by means of static (whole body) and dynamic PET/CT of the lower abdomen and pelvis (dPET/CT) in two consecutive days. The evaluation of PET/CT studies was based on qualitative evaluation, semi-quantitative (SUV) calculation, and quantitative analysis based on two-tissue compartment modeling. ¹⁸F-FDG PET/CT demonstrated focal, ¹⁸F-FDG avid, MM-indicative bone marrow lesions in five patients. In contrary, ¹⁸F-FLT PET/CT showed focal, ¹⁸F-FLT avid, myeloma-indicative lesions in only two patients. In total, 48 ¹⁸F-FDG avid, focal, MM-indicative lesions were detected with ¹⁸F-FDG PET/CT, while 17 ¹⁸F-FLT avid, focal, MM-indicative lesions were detected with ¹⁸F-FLT PET/CT. The number of myeloma-indicative lesions was significantly higher for ¹⁸F-FDG PET/CT than for ¹⁸F-FLT PET/CT. A common finding was a mismatch of focally increased ¹⁸F-FDG uptake and reduced ¹⁸F-FLT uptake (lower than the surrounding bone marrow). Moreover, ¹⁸F-FLT PET/CT was characterized by high background activity in the bone marrow compartment, further complicating the evaluation of bone marrow lesions. Semi-quantitative evaluation revealed that both SUV_mean and SUV_max were significantly higher for ¹⁸F-FLT than for ¹⁸F-FDG in both MM lesions and reference tissue. SUV values were higher in MM lesions than in reference bone marrow for both tracers.

Conclusions

Despite the limited number of patients analyzed in this pilot study, the first results of the trial indicate that ¹⁸F-FLT does not seem suitable as a single tracer in MM diagnostics. Further studies with a larger patient population are warranted to generalize the herein presented results.

Electronic supplementary material

The online version of this article (10.1186/s13550-018-0383-7) contains supplementary material, which is available to authorized users.

Prognostic Value of Baseline 18F-Fluorodeoxyglucose PET/CT in Patients with Multiple Myeloma: A Multicenter Cohort Study

Objective

We investigated the prognostic value of ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography (¹⁸F-FDG PET/CT) in patients with multiple myeloma (MM).

Materials and Methods

Subjects were 76 patients with newly diagnosed myeloma and pretreatment with ¹⁸F-FDG PET/CT from four hospitals. The PET/CT features were evaluated and the clinical characteristics were reviewed. Prognostic factors related to poor progression-free survival (PFS) and overall survival (OS) were identified using a Cox proportional hazards regression model and a prediction scale was developed based on the identified factors.

Results

Multivariate analysis showed that the presence of ¹⁸F-FDG-avid focal bone lesions (≥ 3) was a significant and independent predictor of PFS (hazard ratio [HR] = 3.28, p = 0.007) and OS (HR = 11.78, p = 0.001). The presence of extramedullary disease on PET/CT scan was also a significant predictor of poor PFS (HR = 2.79, p = 0.006) and OS (HR = 3.89, p = 0.003). A prognostic scale was developed using these two predictors. An increase in score on the scale corresponded to a significantly increased risk of poor OS (p = 0.005). In addition, Kaplan-Meier analysis demonstrated that patient survival varied significantly according to the scale (p < 0.001 for OS and p = 0.001 for PFS).

Conclusion

¹⁸F-FDG-avid focal lesions and the presence of extramedullary disease on PET/CT scan are significantly associated with poor OS in MM patients. The scale developed according to these predictors represents a potential prognostic tool for evaluation of patients with MM.

Comparison of whole body magnetic resonance imaging (WBMRI) to whole body computed tomography (WBCT) or 18F-fluorodeoxyglucose positron emission tomography/CT (18F-FDG PET/CT) in patients with myeloma: Systematic review of diagnostic performance

OBJECTIVES

To undertake a systematic review to determine the diagnostic performance of whole body MRI (WBMRI) including diffusion weighted sequences (DWI) compared to whole body computed tomography (WBCT) or 18F-fluorodeoxyglucose positron emission tomography/CT (18F-FDG PET/CT) in patients with myeloma.

METHODS

Two researchers searched the primary literature independently for WBMRI studies of myeloma. Data were extracted focusing on the diagnostic ability of WBMRI versus WBCT and 18F-FDG PET/CT. Meta-analysis was intended.

RESULTS

6 of 2857 articles were eligible that included 147 patients, published from 2008 to 2016. Studies were heterogeneous including both newly diagnosed & relapsed patients. All were single centre studies. Four of the six studies (66.7%) accrued prospectively and 5/6 (83.3%, 3 prospective) included WBMRI and 18F-FDG PET/CT. Three of seven (42.9%) included DWI. The lack of an independent reference standard for individual lesions was noted in 5/6 (83.3%) studies. Studies reported that WBMRI detected more lesions than 18F-FDG PET/CT (sensitivity 68-100% versus 47-100%) but was less specific (specificity 37-83% versus 62-85.7%). No paper assessed impact on management.

CONCLUSIONS

Studies were heterogeneous, the majority lacking an independent reference standard. Future prospective trials should address these limitations and assess the impact of WBMRI on management.

Whole Body MRI and oncology: recent major advances

MRI is a very attractive approach for tumour detection and oncological staging with its absence of ionizing radiation, high soft tissue contrast and spatial resolution. Less than 10 years ago the use of Whole Body MRI (WB-MRI) protocols was uncommon due to many limitations, such as the forbidding acquisition times and limited availability. This decade has marked substantial progress in WB-MRI protocols. This very promising technique is rapidly arising from the research world and is becoming a commonly used examination for tumour detection due to recent technological developments and validation of WB-MRI by multiple studies and consensus papers. As a result, WB-MRI is progressively proposed by radiologists as an efficient examination for an expanding range of indications. As the spectrum of its uses becomes wider, radiologists will soon be confronted with the challenges of this technique and be urged to be trained in order to accurately read and report these examinations. The aim of this review is to summarize the validated indications of WB-MRI and present an overview of its most recent advances. This paper will briefly discuss how this examination is performed and which are the recommended sequences along with the future perspectives in the field.

Functional Imaging Methods for Assessment of Minimal Residual Disease in Multiple Myeloma: Current Status and Novel ImmunoPET Based Methods

Imaging plays a key role in assessment of myeloma. Osteolytic bone lesions are optimally assessed using structural imaging, however the structural changes lag the functional changes in the disease. Functional imaging with fluoro deoxy glucose (FDG) positron emission tomography (PET) computerized tomography (CT) is useful in assessment of high-risk myeloma. FDG PET provides prognostic information and is helpful in monitoring response to therapy. However, it is nonspecific and may not be optimal in assessing treatment response to immunotherapeutic agents. Imaging with targeted agents may allow for better assessment of changes from therapy, that is based on the specific targeted mechanism. ImmunoPET imaging is a novel method to assess targeting of specific antigen by therapeutic antibodies. This review summarizes the role of functional imaging and development of novel immunoPET agents for assessment of treatment response and residual disease.

Current concepts in tumor imaging with whole-body MRI with diffusion imaging (WB-MRI-DWI) in multiple myeloma and lymphoma

Whole-body MRI (WB-MRI) with diffusion-weighted imaging (DWI) can now be used to stage and restage multiple myeloma (MM) and lymphoma. Magnetic resonance imaging (MRI) is the standard tool to detect BM involvement (BMI). The 2016 diagnostic criteria of the International Myeloma Working Group identify WB-MRI and fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) as the most sensitive imaging techniques for detecting skeletal and extra-skeletal MM invasion, respectively. Preliminary findings have also shown that WB-MRI is better than CT and equal to PET/CT in staging aggressive lymphoma and Hodgkin lymphoma, whereas MRI is better for diagnosing BMI in patients with low-grade lymphoma. Signal intensity (SI) and the apparent diffusion coefficient (ADC) are useful metrics to quantify the chemotherapy response in WB-MRI.

Minimal residual disease in multiple myeloma: use of magnetic resonance imaging

The increasing percentage of patients achieving deep responses in multiple myeloma has led to the need for more sophisticated instruments to measure residual disease as a potential source of relapse. As minimal residual disease assessment is mostly performed on a bone marrow specimen from a certain area of the body, such samples have the limitation that they might not really represent the actual tumor burden, because focal accumulations of malignant cells might be either hit or missed. Magnetic resonance imaging is a highly sensitive technique for the assessment of tumor burden and can be performed as whole-body protocol, overcoming the problem of sampling error for minimal residual disease assessment. Despite its high sensitivity, however, magnetic resonance imaging cannot differentiate between vital and necrotic lesions after therapy. Therefore, new fusion and functional techniques are currently under investigation, and image-guided biopsies are performed to combine the strengths of all available methods.

Whole Body MRI and oncology: recent major advances

MRI is a very attractive approach for tumour detection and oncological staging with its absence of ionizing radiation, high soft tissue contrast and spatial resolution. Less than 10 years ago the use of Whole Body MRI (WB-MRI) protocols was uncommon due to many limitations, such as the forbidding acquisition times and limited availability. This decade has marked substantial progress in WB-MRI protocols. This very promising technique is rapidly arising from the research world and is becoming a commonly used examination for tumour detection due to recent technological developments and validation of WB-MRI by multiple studies and consensus papers. As a result, WB-MRI is progressively proposed by radiologists as an efficient examination for an expanding range of indications. As the spectrum of its uses becomes wider, radiologists will soon be confronted with the challenges of this technique and be urged to be trained in order to accurately read and report these examinations. The aim of this review is to summarize the validated indications of WB-MRI and present an overview of its most recent advances. This paper will briefly discuss how this examination is performed and which are the recommended sequences along with the future perspectives in the field.

Shall we treat smoldering multiple myeloma in the near future?

In recent years, several new drugs have been approved for the treatment of multiple myeloma. Many of these newer drugs are highly efficacious and less toxic than older chemotherapy drugs. In 2014, the diagnostic criteria for multiple myeloma were revised. The intent with the new criteria was to identify patients who require therapy at an earlier stage than at manifestation of organ complications. A subset of patients who were previously defined as having high-risk smoldering multiple myeloma was redefined as having multiple myeloma. In this context, it is logical to raise questions regarding the optimal clinical management of patients who are diagnosed with smoldering multiple myeloma in the current era. When is the optimal time to start therapy? Do the clinical trajectories for patients suggest there are distinct sub-entities hidden in the current category of smoldering multiple myeloma? How can we move the field forward from here? This paper reviews and dissects data and models on the topics of clinical features, underlying biology, and early treatment trials in smoldering multiple myeloma. The text highlights assumptions, facts, and gaps in the literature. As indicated in the title of the paper, the recurrent theme of the text is this: shall we treat smoldering multiple myeloma in the near future?

Prognostic significance of tumor burden assessed by whole-body magnetic resonance imaging in multiple myeloma patients treated with allogeneic stem cell transplantation

Allogeneic stem cell transplantation is a therapeutic option under dispute but nonetheless chosen with increasing frequency for patients suffering from multiple myeloma in Europe. To study possible predictors of survival, 79 patients were investigated using whole-body magnetic resonance imaging to assess the visible tumor burden before and after allogeneic stem cell transplantation. Statistical analysis of clinical and imaging parameters included Cox regression models and distribution of survival time estimates (Kaplan-Meier method). Log rank test was used to determine the prognostic impact of the presence of focal lesions on survival. A higher tumor burden according to the lesion count was associated with a shorter overall survival (univariable/multivariable Cox regression: 1^st magnetic resonance imaging P=0.028/P=0.048; 2^nd magnetic resonance imaging P=0.008/P=0.024). Focal infiltration pattern itself seemed to be an additional adverse prognostic factor for overall survival (2^nd MRI P=0.048), although no definite cut-off could be defined. Kaplan-Meier estimates at 60 months of follow up show a significant difference (Log rank P=0.04) for overall survival rates between patients with focal infiltration (32%) and those without (75%). Since this subgroup of patients may benefit from maintenance therapy, adoptive immunotherapy, or local interventions, whole-body imaging is an appropriate and highly recommendable diagnostic approach for detection of prognostically relevant lesions before and after treatment.

[Focal lesions in whole-body MRI in multiple myeloma : Quantification of tumor mass and correlation with disease-related parameters and prognosis]

BACKGROUND AND OBJECTIVES

In this study, we evaluated methods of quantification of tumor mass in whole-body MRI (wb-MRI) in multiple myeloma and correlated these with disease-related parameters in serum and bone marrow.

MATERIALS AND METHODS

We retrospectively evaluated wb-MRIs of 52 patients with focal infiltration pattern and a total of 700 focal lesions (subsequently called lesions). We determined the longest diameter (LD), the segmented volume (SV), and the morphology (spherical or non-spherical). We correlated total number/volume of the lesions with clinical parameters and prognosis and furthermore LD with SV. After that we analyzed the agreement of SV and estimated volume (EV) using the volume formula of a sphere based on LD.

RESULTS

Results showed no significant correlations of total number/volume with prognosis or clinical parameters. The latter were situated predominantly in the normal range. Furthermore, 10% of lesions were spherical. SV and LD correlated significantly in single lesions and on patient level. SV was in lesions <6 cm³ systematically larger and in lesions ≥6 cm³ smaller than EV. In 95%, we found in small lesions a deviation of EV versus SV from +0.9 cm³ to -4.6 cm³ and in large lesions from +160 cm³ to -111 cm³ (EV-SV).

CONCLUSIONS

Quantification of tumor mass in the focal infiltration pattern is performed more accurately by volumetry than LD due to the predominant existence of non-spherical lesions. The patient cohort with clinical parameters predominantly in the normal range is distributed to ISS stage I and partly pretreated, a fact that makes interpretation of absent correlations more difficult. Consider also a variation in activitiy of lesions and a diffuse infiltration not detectable by MRI.

Whole-body computed tomography versus conventional skeletal survey in patients with multiple myeloma: a study of the International Myeloma Working Group

For decades, conventional skeletal survey (CSS) has been the standard imaging technique for multiple myeloma (MM). However, recently whole-body computed tomography (WBCT) has been implemented into the diagnostic criteria of MM. This analysis compares sensitivity and prognostic significance of WBCT and CSS in patients with smoldering MM (SMM) and MM. Fifty-four of 212 patients (25.5%) had a negative CSS and a positive WBCT for osteolytic lesions (P<0.0001). Of 66 patients with SMM based on CSS, 12 (22.2%) had osteolytic lesions on WBCT. In comparison, WBCT failed to detect some bone destructions in the appendicular skeleton possibly due to limitations of the field of view. Presence of lytic bone lesions in WBCT was of borderline prognostic significance (P=0.051) for SMM patients, with a median time to progression of 38 versus 82 months for those without bone destructions. In conclusion, WBCT identifies significantly more sites of bone destruction than CSS. More than 20% of patients with SMM according to CSS have in fact active MM detectable with WBCT. On the basis of this and other studies, WBCT (either computed tomography (CT) alone or as part of a positron emission tomography-CT protocol) should be considered the current standard for the detection of osteolytic lesions in MM.

Non-Secretory Myeloma: Ready for a new Definition?

Non-secretory myeloma is a rare myeloma subtype whose diagnosis, until a few years ago, was established by demonstration of monoclonal plasma cells ≥10% in the bone marrow and by negative results on serum and urine electrophoresis and immunofixation studies. However, this type of myeloma could be misdiagnosed if the workup does not include an accurate study of serum free light chain test since some of the patients diagnosed as non-secretory could be light chain only with small amounts monoclonal proteinuria. Due to this limit in classification, all the information available today, generally coming from retrospective studies including patients studied completely and incompletely, could be misleading. A new definition is, thus, needed to distinguish between the true non-secretory, with a possible better prognosis, and the other forms of oligo-secretory myeloma with a prognosis more similar to the secretory form of myeloma. With all the data of the literature, the availability of laboratory and radiological tools, times are mature to depict a new definition of nonsecretory myeloma that deserves a peculiar work up and different response evaluation and, may be, a different therapeutic approach.

Guidelines for the use of imaging in the management of patients with myeloma

The role of imaging in myeloma has gained increasing importance over the past few years. The recently revised definition of myeloma from the International Myeloma Working Group (IMWG) includes cross sectional imaging as a method to define bone disease and also incorporates its use in the disease definition for patients with suspected smouldering myeloma. The National Institute for Health and Care Excellence myeloma guidelines also recommend cross sectional imaging for patients with suspected myeloma. There is also increasing use of imaging in disease assessments and the International Myeloma Working Group has recently incorporated imaging in defining new response categories of minimal residual disease negativity, with or without imaging-based evidence of disease. Plain X-rays have previously been the standard imaging modality included in a myeloma work up at presentation but evidence is mounting for use of cross-sectional modalities such as computed tomography (CT), magnetic resonance imaging (MRI) and 18 fluoro-deoxyglucose (18 F-FDG) positron emission tomography (PET)/CT. Funding and therefore availability of newer imaging techniques remains a barrier. Here, we propose an evidence-based approach to the use and technical application of the latest imaging modalities at diagnosis and in the follow-up of patients with myeloma and plasmacytoma.

Prospective Evaluation of Magnetic Resonance Imaging and [18F]Fluorodeoxyglucose Positron Emission Tomography-Computed Tomography at Diagnosis and Before Maintenance Therapy in Symptomatic Patients With Multiple Myeloma Included in the IFM/DFCI 2009 Trial: Results of the IMAJEM Study

Purpose Magnetic resonance imaging (MRI) and positron emission tomography-computed tomography (PET-CT) are important imaging techniques in multiple myeloma (MM). We conducted a prospective trial in patients with MM aimed at comparing MRI and PET-CT with respect to the detection of bone lesions at diagnosis and the prognostic value of the techniques. Patients and Methods One hundred thirty-four patients received a combination of lenalidomide, bortezomib, and dexamethasone (RVD) with or without autologous stem-cell transplantation, followed by lenalidomide maintenance. PET-CT and MRI were performed at diagnosis, after three cycles of RVD, and before maintenance therapy. The primary end point was the detection of bone lesions at diagnosis by MRI versus PET-CT. Secondary end points included the prognostic impact of MRI and PET-CT regarding progression-free (PFS) and overall survival (OS). Results At diagnosis, MRI results were positive in 127 of 134 patients (95%), and PET-CT results were positive in 122 of 134 patients (91%; P = .33). Normalization of MRI after three cycles of RVD and before maintenance was not predictive of PFS or OS. PET-CT became normal after three cycles of RVD in 32% of the patients with a positive evaluation at baseline, and PFS was improved in this group (30-month PFS, 78.7% v 56.8%, respectively). PET-CT normalization before maintenance was described in 62% of the patients who were positive at baseline. This was associated with better PFS and OS. Extramedullary disease at diagnosis was an independent prognostic factor for PFS and OS, whereas PET-CT normalization before maintenance was an independent prognostic factor for PFS. Conclusion There is no difference in the detection of bone lesions at diagnosis when comparing PET-CT and MRI. PET-CT is a powerful tool to evaluate the prognosis of de novo myeloma.

Role of 18F-FDG PET/CT in the diagnosis and management of multiple myeloma and other plasma cell disorders: a consensus statement by the International Myeloma Working Group

The International Myeloma Working Group consensus aimed to provide recommendations for the optimal use of ¹⁸fluorodeoxyglucose (¹⁸F-FDG) PET/CT in patients with multiple myeloma and other plasma cell disorders, including smouldering multiple myeloma and solitary plasmacytoma. ¹⁸F-FDG PET/CT can be considered a valuable tool for the work-up of patients with both newly diagnosed and relapsed or refractory multiple myeloma because it assesses bone damage with relatively high sensitivity and specificity, and detects extramedullary sites of proliferating clonal plasma cells while providing important prognostic information. The use of ¹⁸F-FDG PET/CT is mandatory to confirm a suspected diagnosis of solitary plasmacytoma, provided that whole-body MRI is unable to be performed, and to distinguish between smouldering and active multiple myeloma, if whole-body X-ray (WBXR) is negative and whole-body MRI is unavailable. Based on the ability of ¹⁸F-FDG PET/CT to distinguish between metabolically active and inactive disease, this technique is now the preferred functional imaging modality to evaluate and to monitor the effect of therapy on myeloma-cell metabolism. Changes in FDG avidity can provide an earlier evaluation of response to therapy compared to MRI scans, and can predict outcomes, particularly for patients who are eligible to receive autologous stem-cell transplantation. ¹⁸F-FDG PET/CT can be coupled with sensitive bone marrow-based techniques to detect minimal residual disease (MRD) inside and outside the bone marrow, helping to identify those patients who are defined as having imaging MRD negativity.

Whole-body MRI, dynamic contrast-enhanced MRI, and diffusion-weighted imaging for the staging of multiple myeloma

Magnetic resonance imaging (MRI) is the most sensitive imaging technique for the detection of bone marrow infiltration, and has therefore recently been included in the new diagnostic myeloma criteria, as proposed by the International Myeloma Working Group. Nevertheless, conventional MRI only provides anatomical information and is therefore only of limited use in the response assessment of patients with multiple myeloma. The additional information from functional MRI techniques, such as diffusion-weighted imaging and dynamic contrast-enhanced MRI, can improve the detection rate of bone marrow infiltration and the assessment of response. This can further enhance the sensitivity and specificity of MRI in the staging of multiple myeloma patients. This article provides an overview of the technical aspects of conventional and functional MRI techniques with practical recommendations. It reviews the diagnostic performance, prognostic value, and role in therapy assessment in multiple myeloma and its precursor stages.

Application of PET/CT in treatment response evaluation and recurrence prediction in patients with newly-diagnosed multiple myeloma

Multiple myeloma (MM) causes osteolytic lesions which can be detected by 18F-fluorodeoxyglucose positron emission tomography/Computed tomography (18F-FDG PET/CT). We prospectively involve 96 Newly diagnosed MM to take PET/CT scan at scheduled treatment time (figure 1), and 18F-FDG uptake of lesion was measured by SUVmax and T/Mmax. All MM patients took bortezomib based chemotherapy as induction and received ASCT and maintenance. All clinical features were analyzed with the PET/CT image changes, and some relationships between treatment response and FDG uptakes changes were found: Osteolytic lesions of MM uptakes higher FDG than healthy volunteers, and this trend is more obvious in extramedullary lesions. Compared to X-ray, PET/CT was more sensitive both in discoering bone as well as extramedullary lesions. In newly diagnosed MM, several adverse clinical factors were related to high FDG uptakes of bone lesions. Bone lesion FDG uptakes of MM with P53 mutation or with hypodiploidy and complex karyotype were also higher than those without such changes. In treatment response, PET/CT showed higher sensitivity in detecting tumor residual disease than immunofixation electrophoresis. But in relapse prediction, it might show false positive disease recurrences and the imaging changes might be influenced by infections and hemoglobulin levels. Conclusion: PET/CT is sensitive in discovering meduallary and extrameduallary lesions of MM, and the 18F-FDG uptake of lesions are related with clinical indictors and biological features of plasma cells. In evaluating treatment response and survival, PET/CT showed its superiority. But in predicting relapse or refractory, it may show false positive results.

PET/MR Imaging of Multiple Myeloma

PET-magnetic resonance (MR) is a hybrid imaging modality that combines PET and MR. Evidence for this new modality is in the process of being developed, but both component modalities are well tested in the diagnosis and management of multiple myeloma. It allows advanced bimodality imaging of the whole body with an adaptable field of view and it can be used for monitoring plasma cell dyscrasias for progression to multiple myeloma, for assessing disease burden in patients with known multiple myeloma, for assessing response to therapy and relapse after remission, and for radiation therapy treatment planning.

PET Imaging for Initial Staging and Therapy Assessment in Multiple Myeloma Patients

Multiple myeloma (MM) is a hematological neoplasm characterized by the clonal proliferation of malignant plasma cells in the bone marrow. MM results in diffuse or focal bone infiltration and extramedullary lesions. Over the past two decades, advances have been made with regard to the diagnosis, staging, treatment, and imaging of MM. Computed tomography (CT) and magnetic resonance imaging (MRI) are currently recommended as the most effective imaging modalities at diagnostic. Yet, recent data from the literature suggest that positron emission tomography combined with computed tomography (PET/CT) using 18F-deoxyglucose (FDG) is a promising technique for initial staging and therapeutic monitoring in this pathology. This paper reviews the recent advances as well as the potential place of a more specific radiopharmaceutical in MM.

The Role of Imaging in the Treatment of Patients With Multiple Myeloma in 2016

The novel criteria for the diagnosis of symptomatic multiple myeloma have revealed the value of modern imaging for the management of patients with myeloma. Whole-body low-dose CT (LDCT) has increased sensitivity over conventional radiography for the detection of osteolytic lesions, and several myeloma organizations and institutions have suggested that whole-body LDCT should replace conventional radiography for the work-up of patients with myeloma. MRI is the best imaging method for the depiction of marrow infiltration by myeloma cells. Whole-body MRI (or at least MRI of the spine and pelvis if whole-body MRI is not available) should be performed for all patients with smoldering multiple myeloma with no lytic lesions to look for occult disease, which may justify treatment. In addition, MRI accurately illustrates the presence of plasmacytomas, spinal cord, and/or nerve compression for surgical intervention or radiation therapy; it is also recommended for the work-up of solitary bone plasmacytoma, and it may distinguish malignant from benign fractures (which is very important in cases of patients in biochemical remission with no other signs of progression). Diffusion weighted imaging (DWI) seems to improve MRI diagnosis in patients with myeloma. PET/CT is a functional imaging technique, more sensitive than conventional radiography for the detection of lytic lesions, which probably allows better definition of complete response and minimal residual disease compared with all other imaging methods. PET/CT has shown the best results in the follow-up of patients with myeloma and has an independent prognostic value both at diagnosis and following treatment. PET/CT can also be used for the work-up of solitary bone plasmacytoma and nonsecretory myeloma.

Fluorodeoxyglucose Positron Emission Tomography-Computed Tomography (FDG PET/CT) Findings in an Unusual Case of Multiple Myeloma Presenting with a Large Extra-Axial Intracranial Mass

Background

We aimed to present unusual cranial FDG PET/CT findings of a 56-year-old female with multiple myeloma (MM).

Case Report

Plain CT images revealed a lytic lesion in the right parietal bone, filled with an oval-shaped, large, extra-axial, extradural, intracranial mass which measured 75×75×40 mm and had smooth borders. The right parietal lobe was compressed by the mass. The maximum standardized uptake value (SUV_max) of the mass lesion was 8.94 on FDG PET/CT images. Multiple lytic lesions with an increased uptake were also detected in other calvarial bones, in several vertebras and in the proximal left femur. After seven months, a control FDG PET/CT following radiotherapy and chemotherapy revealed almost complete regression of the right parietal extra-axial mass lesion. The number, size and metabolism of lytic lesions in other bones also decreased.

Conclusions

FDG PET/CT was useful for an initial evaluation of MM lesions and was effective in monitoring the response of these lesions to therapy.

Whole body magnetic resonance imaging in newly diagnosed multiple myeloma: early changes in lesional signal fat fraction predict disease response

Cross-sectional imaging techniques are being increasingly used for disease evaluation in patients with multiple myeloma. Whole body magnetic resonance imaging (WB-MRI) scanning is superior to plain radiography in baseline assessment of patients but changes following treatment have not been systematically explored. We carried out paired WB-MRI scans in 21 newly diagnosed patients prior to, and 8-weeks after, starting chemotherapy, and analysed stringently selected focal lesions (FLs) for parametric changes. A total of 323 FLs were evaluated, median 20 per patient. At 8 weeks, there was a reduction in estimated tumour volume (eTV), and an increase in signal fat fraction (sFF) and apparent diffusion coefficient (ADC) in the group as a whole (P < 0·001). Patients who achieved complete/very good partial response (CR/VGPR) to induction had a significantly greater increase in sFF compared to those achieving ≤ partial response (PR; P = 0·001). When analysed on a per-patient basis, all patients achieving CR/VGPR had a significant sFF increase in their FL's, in contrast to patients achieving ≤PR. sFF changes in patients reaching maximal response within 100 days (fast responders) were greater compared to slow responders (P = 0·001). Receiver Operator Characteristic analysis indicated that sFF changes at 8 weeks were the best biomarker (area under the Curve 0·95) for an inferior response (≤PR). We conclude that early lesional sFF changes may provide important information on depth of response, and are worthy of further prospective study.

Non-secretory multiple myeloma: from biology to clinical management

Multiple myeloma (MM) is the second most common hematologic malignancy in the US. It is typically characterized by production of large amounts of defective immunoglobulin (Ig). Diagnosing MM and monitoring treatment response, including eventual relapse, are largely based on sequential measurements of Ig. However, a small subset of MM called non-secretory multiple myeloma (NSMM) produces no detectable Ig. This subset of true NSMM has become even smaller over time, as the advent of the serum free light chain assay has resulted in the majority of NSMM patients being recategorized as light-chain MM – that is, MM cells that produce only the light-chain component of Ig. True forms of NSMM, meaning MM that secretes no monoclonal proteins whatsoever, constitute a distinct entity that is reviewed; definition of NSMM using current detection methods, discuss the biology underpinning NSMM development, and share recommendations for how NSMM should be managed clinically with respect to detection, treatment, and monitoring.

Next-generation multiple myeloma treatment: a pharmacoeconomic perspective

Advances in the diagnosis and treatment of multiple myeloma have come at a rapid pace, especially with several new drugs entering the market in the last few years. However, access to and affordability of new treatments poses a major challenge, both in the United States and around the world. High costs of life-saving drugs are detrimental to both the personal finances of the individual patient, as well as society which must bear the increasing costs in terms of increased health insurance premiums, taxes, or both. The challenges are not unique to myeloma, but are commonly encountered in several other cancers as well. But to some extent these pharmacoeconomic concerns are amplified in myeloma due to the need for multidrug regimens that combine 2 or more expensive new drugs, continuous therapy, and the prolonged disease course in most patients. We examine current myeloma therapy from a pharmacoeconomic perspective, and discuss the costs involved. We outline the underlying reasons why cancer drugs are so expensive, the measures that are required to lower cost, and propose potential ways in which costs can be reduced while still delivering high-quality care.

FDG-PET imaging in hematological malignancies

The majority of aggressive lymphomas is characterized by an up regulated glycolytic activity, which enables the visualization by F-18 FDG-PET/CT. One-stop hybrid FDG-PET/CT combines the functional and morphologic information, outperforming both, CT and FDG-PET as separate imaging modalities. This has resulted in several recommendations using FDG-PET/CT for staging, restaging, monitoring during therapy, and assessment of treatment response as well as identification of malignant transformation. FDG-PET/CT may obviate the need for a bone marrow biopsy in patients with Hodgkin's lymphoma and diffuse large B cell lymphoma. FDG-PET/CT response assessment is recommended for FDG-avid lymphomas, whereas CT-based response evaluation remains important in lymphomas with low or variable FDG avidity. The treatment induced change in metabolic activity allows for assessment of response after completion of therapy as well as prediction of outcome early during therapy. The five-point scale Deauville Criteria allows the assessment of treatment response based on visual FDG-PET analysis. Although the use of FDG-PET/CT for prediction of therapeutic response is promising it should only be conducted in the context of clinical trials. Surveillance FDG-PET/CT after complete remission is discouraged due to the relative high number of false-positive findings, which in turn may result in further unnecessary investigations. Future directions include the use of new PET tracers such as F-18 fluorothymidine (FLT), a surrogate biomarker of cellular proliferation and Ga-68 CXCR4, a chemokine receptor imaging biomarker as well as innovative digital PET/CT and PET/MRI techniques.

Bone mineral density utilization in patients with newly diagnosed multiple myeloma

Bone disease is a major cause for morbidity in multiple myeloma (MM), with the main focus concerning the manifestation as osteolytic lesions. Bone mineral loss is another reflection of myeloma bone involvement. Recently, osteoporosis has been omitted as a defining criterion for symptomatic disease in MM. We conducted a retrospective study to evaluate the use of bone mineral density (BMD) exams by dual-energy X-ray absorptiometry (DXA) among MM patients in a tertiary medical care centre. One-hundred seventy three patients were included. The T-scores of lumbar spine (LS), left femur neck (FN) and left total hip (TH) were obtained and analysed. The extent of osteolytic disease was categorized based on six bony areas. There was a strong correlation between spine and femur's T-scores (r = 0.56-0.61, p < 0.0001), although different sets of variables were correlated with LS and femur's T-scores. There was no correlation between BMD measurements and osteolytic disease extent. Patients with vertebral fracture(s) had significant lower T-scores of the spine in comparison to patients without vertebral fractures. Sixty-three patients (36.4% of the cohort) had follow-up DXA exam. In general, there was an increase in the LS T-scores, while femoral values decreased. However, in patients who achieved complete response (CR) and in those who retained CR during follow-up, femoral BMD increased as well. Because correlation between BMD and the extent of osteolytic lesions was not seen, our data support the recent exclusion of BMD assessment from the definition of symptomatic myeloma. Still, its use should be considered for evaluation of age- or therapy-related osteoporosis. Copyright © 2016 John Wiley & Sons, Ltd.

State-of-the-Art Imaging and Staging of Plasma Cell Dyscrasias

Monoclonal gammopathy of unknown significance (MGUS) is a clinically asymptomatic premalignant clonal plasma cell or lymphoplasmacytic proliferative disorder. Smoldering multiple myeloma, also called asymptomatic multiple myeloma, is an intermediate stage between MGUS and symptomatic multiple myeloma. As the name implies, extraosseous or extramedullary myeloma refers to the presence of myeloma deposits outside the skeletal system. Waldenström macroglobulinemia is a distinct subtype of plasma cell dyscrasia characterized by lymphoplasmacytic lymphoma in the bone marrow with an associated IgM monoclonal gammopathy. Amyloidosis is a condition characterized by extracellular deposition of fibrils composed of a variety of normal serum proteins.