18F-FDG PET/CT: a review of diagnostic and prognostic features in multiple myeloma and related disorders

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.

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.

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.

In vitro and ex vivo anti-myeloma effects of nanocomposite As4S4/ZnS/Fe3O4

Nanoparticles in medicine can integrate actively targeted imaging agents and drug delivery vehicles, and combining multiple types of therapeutics in a single particle has numerous advantages, especially in multiple myeloma. MM is an incurable hematological disorder characterized by clonal proliferation of plasma cells in the bone marrow. In this study, we evaluated the anti-myeloma activity of 3 nanocomposites (3NPs): As₄S₄/ZnS/Fe₃O₄ (1:4:1), As₄S₄/ZnS/Fe₃O₄ with folic acid (FA), and As₄S₄/ZnS/Fe₃O₄ with FA and albumin with reduced survival MM cell lines and primary MM samples by each of 3NP. Cytotoxic effects of 3NPs were associated with caspase- and mitochondria-dependent apoptosis induction and reduced c-Myc expression. Modulation of cell cycle regulators, such as p-ATM/ATM and p-ATR/ATR, and increases in p-Chk2, cyclin B1, and histones were accompanied by G₂/M arrest triggered by 3NPs. In addition, 3NPs activated several myeloma-related signaling, including JNK1/2/3, ERK1/2 and mTOR. To overcome BM microenvironment-mediated drug resistance, nanocomposites retained its anti-MM activity in the presence of stroma. 3NPs significantly decreased the stem cell-like side population in MM cells, even in the context of stroma. We observed strong synergistic effects of 3NPs combined with lenalidomide, pomalidomide, or melphalan, suggesting the potential of these combinations for future clinical studies.

M, Kumar SP, Krishnan M. A Rare Case of Hormone-Induced Plasma Cell Granuloma of the Gingiva

Plasma cell granuloma (PCG), also known as inflammatory pseudotumor, is of unknown etiopathogenesis. It commonly presents in the lungs and can also occur in the liver, kidney, brain, and heart. PCG is rare in the oral cavity and even rarer in the gingiva. The clinical and radiological presentation of this disease in the oral cavity appears to be aggressive in nature and is often misdiagnosed as a malignant lesion. Histopathology helps in distinguishing PCG of gingiva from other benign and malignant lesions of the gingiva. Amlodipine and cyclosporine-induced PCG of gingiva have been reported in the literature. This report presents a rare case of generalized plasma cell granuloma of the gingiva in an adult female patient who was on hormonal therapy for infertility. Treatment consisted of complete surgical excision of the lesion and extraction of teeth with a poor prognosis. Wound healing was uneventful during the one-year follow-up period with no signs of recurrence.

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.

Diagnostic value of 18F-FDG PET/CT and MRI for intraspinal lesions: A comparative study

The aim of the present study was to investigate the value of the use of fluorine-18 (¹⁸F)-fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT) vs. magnetic resonance imaging (MRI) for the diagnosis of and differentiation between benign and malignant lesions in the spinal canal. For this purpose, a retrospective analysis was performed on the use of MRI and ¹⁸F-FDG PET/CT from January, 2017 to December, 2020, and the final diagnosis was obtained by performing a post-operative pathological examination or following a tissue biopsy (gold standard). The sensitivity, specificity, accuracy, positive predictive value and negative predictive value of the two examination techniques were calculated and comparisons between them were made. The PET metabolic parameters, maximum standardized uptake value (SUVmax), peak standardized uptake value (SUVpeak), mean standardized uptake value (SUVmean), metabolic tumor volume (MTV) and total lesion glycolysis (TLG) in the benign and malignant groups were calculated and compared, and the corresponding ROC curves were plotted. A total of 58 patients were enrolled, including 30 patients with malignant and 28 with benign lesions. The specificity of MRI was significantly higher than that of PET/CT (P<0.05). The sensitivity and negative predictive value of PET/CT were higher than those of MRI, although with no significant difference (P>0.05). The mean ± tandard deviation values of the PET metabolic parameters, SUVmax, SUVpeak, SUVmean, MTV and TLG, were 4.27±1.25, 3.49±1.07, 2.49±0.84, 6.58±5.36 and 17.12±15.50 in the benign, and 8.99±3.75, 7.35±3.26, 5.43±2.40, 12.25±12.18 and 112.41±85.98 in the malignant groups, respectively. The SUVmax, SUVpeak, SUVmean and TLG in the malignant group were higher than those in the benign group. The differences were all statistically significant (all P<0.0001). In distinguishing benign from malignant lesions, the area under the ROC curve (AUC) for SUVmax was 0.919, which was the largest, and the Youden index was 0.762, indicating 83.3% sensitivity and 92.9% specificity. The AUC for SUVpeak was 0.905 and that for SUVmean was 0.899. The aforementioned AUCs were significantly higher than those for MTV and TLG (0.609 and 0.786, respectively) (P<0.001). On the whole, the present study demonstrates that MRI is a reliable imaging technique for the diagnosis of intravertebral lesions. ¹⁸F-FDG PET/CT, as a noteworthy supplement to MRI, has a high sensitivity and accuracy for the qualitative diagnosis and identification of lesions. The synergistic effect of the two examination techniques may be helpful for a more accurate diagnosis.

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.

Prognostic and predictive biomarker developments in multiple myeloma

New approaches to stratify multiple myeloma patients based on prognosis and therapeutic decision-making, or prediction, are needed since patients are currently managed in a similar manner regardless of individual risk factors or disease characteristics. However, despite new and improved biomarkers for determining the prognosis of patients, there is currently insufficient information to utilise biomarkers to intensify, reduce or altogether change treatment, nor to target patient-specific biology in a so-called predictive manner. The ever-increasing number and complexity of drug classes to treat multiple myeloma have improved response rates and so clinically useful biomarkers will need to be relevant in the era of such novel therapies. Therefore, the field of multiple myeloma biomarker development is rapidly progressing, spurred on by new technologies and therapeutic approaches, and underpinned by a deeper understanding of tumour biology with individualised patient management the goal. In this review, we describe the main biomarker categories in multiple myeloma and relate these to diagnostic, prognostic and predictive applications.

Fluorodeoxyglucose PET/CT of Arthritis in Rheumatic Diseases: A Pictorial Review

Rheumatic diseases are various painful conditions that affect joints, bones, cartilage, tendons, ligaments, and muscles. Arthritis is a typical condition of rheumatic disease. Although rheumatoid arthritis is a representative rheumatic disease, various diseases other than rheumatoid arthritis can also affect joints, and differential diagnosis of rheumatic diseases is often difficult owing to the similar clinical manifestations. However, accurate diagnosis is crucial for an appropriate treatment strategy. The utility of fluorine 18 fluorodeoxyglucose (FDG) PET/CT has been established, and it is widely used for assessing malignancies. In addition to accumulating in tumor cells, FDG also accumulates in inflammatory tissue, allowing FDG PET/CT to demonstrate arthritis. PET/CT allows evaluation of whole-body articular and extra-articular lesions in one examination, representing a key advantage over US and MRI, which allow assessment of only a few regions because of their limited field of view. Although FDG PET/CT is sensitive for detecting inflammatory lesions, the uptake itself is nonspecific; therefore, knowledge of characteristic uptake patterns is necessary to narrow the differential diagnosis in rheumatic disease. Furthermore, pathognomonic extra-articular findings such as vasculitis, skin lesions, lymphadenopathy, and chondritis play an important role in achieving accurate diagnosis. The authors present the FDG PET/CT appearances of (a) rheumatoid arthritis and allied disorders (polymyalgia rheumatica, remitting seronegative symmetrical synovitis with pitting edema, adult-onset Still disease), (b) spondyloarthritis (ankylosing spondylitis, psoriatic arthritis, reactive arthritis, inflammatory bowel disease arthritis, SAPHO [synovitis, acne, pustulosis, hyperostosis, and osteitis] syndrome, chronic recurrent multifocal osteomyelitis), and (c) miscellaneous systemic disorders with arthropathy (relapsing polychondritis, multicentric reticulohistiocytosis, amyloidosis, sarcoidosis, hemophilia). ^©RSNA, 2020.

The status of jaw lesions and medication-related osteonecrosis of jaw in patients with multiple myeloma

BACKGROUND/PURPOSE

Myeloma jaw lesions are not uncommon. The study aimed to investigate the status of jaw lesions and medication-related osteonecrosis of jaw (MRONJ) in multiple myeloma (MM) patients.

METHODS

One hundred and twenty-two consecutive newly-diagnosed MM patients seeking dental care at a hospital of southern Taiwan was examined according to jaw lesions with complete follow-up data.

RESULTS

Median age of the patients was 67.8 years, and 88.5% of patients were of DS stage III and 41.0% were of ISS stage III at diagnosis. Median survival was 37.9 months for 43 (35.2%) patients with jaw lesions and 57.4 months for 79 patients without jaw lesions. 1-year, 5-year and >7-year overall survival rates for patients with jaw lesions versus patients without jaw lesions were 94.9%, 67.2%, 56.7% vs 83.7%, 51.8%, 26.8% respectively. Patients with jaw lesions had the worse survival (P = 0.03). Neither age nor stage affected survival. Jaw lesions involved the mandible more often than the maxilla and stopped progressing during remission, but did not repair. Jaw lesions were the first evidence or recurrent sign of MM in six (4.9%) patients. Long-term monthly antiresorptive therapy changed the radiographic patterns of jawbones and induced MRONJ developing in 16.7% (8/48) of patients. Five (62.5%) MRONJ sites spontaneously occurred without local risk factors.

CONCLUSION

Nearly one-third of MM patients develop osteolytic jaw lesions that seem to be associated with poorer survival. Jaw lesion is an independent prognostic predictor of survival in myeloma. Antiresorptive drugs at less frequent dosing regimen are crucial to minimize spontaneous MRONJ.

PET/CT in Multiple Myeloma: Beyond FDG

Recent advances in the diagnosis and treatment of multiple myeloma (MM) have highlighted the importance of imaging methods, not only in the localization and extent of the disease but also in prognostic stratification and assessment of response to therapy. In this context, PET/CT, combining both morphological and functional information, is particularly useful in this pathology. The tracer mostly used is 18F-FDG, a glucose analog, which provides extremely accurate information with a sensitivity ranging from 80 to 100%. However, this tracer has some limitations, mostly related to the physiological uptake of FDG in the bone marrow and brain, which reduce its effectiveness. For this reason, some studies in the literature have evaluated the effectiveness of other PET tracers, which provide information on protein metabolism or the synthesis of metabolic plasma membranes, such as choline and methionine, as well as innovative radiopharmaceuticals, directed against receptors expressed by cells of myeloma, including tracers directed to the chemokine receptor. This review analyzes the characteristics and accuracy of non-FDG tracers in the management of patients with multiple myeloma.

The Spectrum of Rib Neoplasms in Adults: A Practical Approach and Multimodal Imaging Review

OBJECTIVE. Adult neoplasms of the ribs are a heterogeneous group consisting of both benign and aggressive entities. Rib neoplasms have a variety of overlapping imaging features, with much of the imaging data disjointed across the musculoskeletal, thoracic, and oncologic imaging literature. Arrival at accurate diagnosis can therefore be quite challenging. This article consolidates this information and introduces the reader to an algorithmic approach to rib lesion evaluation based on imaging. CONCLUSION. Rib neoplasms are a diverse group of benign and malignant entities, which often makes determining an accurate diagnosis challenging. Evaluation requires a multipronged approach that incorporates radiographic imaging features, nonradiographic imaging findings, lesion location, and clinical data.

The role of CT in PET/CT for assessing diffuse infiltration of bone marrow in multiple myeloma using the Durie-Salmon PLUS staging system

PET/CT has been identified as one of the routine methods for the assessment of multiple myeloma (MM) bone marrow infiltration. In the routine method of performing PET/CT, the 18F-Fludeoxyglucose (¹⁸F-FDG) uptake in this disease is often used in the assessment of this condition, however CT diagnosis is not currently commonly used. The aim of the present study was to investigate the importance of CT in PET/CT for assessing diffuse infiltration (DI) of bone marrow in MM. MRI was used as a control in the present study, which is the gold standard for assessing DI of bone marrow and is divided into 3 levels: Mild, moderate and severe DI. Subsequently, a total of four combinations of PET and CT results were listed using the enumeration method for the evaluation of DI in the bone marrow. These combinations were respectively compared with the three levels of MR imaging to screen the most consistent method. The concordances of the new method and routine ¹⁸F-FDG PET/CT for the assessment of DI with MR imaging were compared using the McNemar test, respectively. The results of the DI assessment from the two methods were verified by performing Durie-Salmon (D-S) PLUS staging. Compared with MR imaging, the results were as follows: PET and CT exhibited negative results, suggesting mild DI; one of them was positive, suggesting moderate DI; and two were positive, suggesting severe DI. The results of concordance between two methods (new and routine) and MR imaging are indicated as follows: For the new method, McNemar test, P=0.513 and Kappa=0.745; for the routine ¹⁸F-FDG PET/CT method, McNemar test, P=0.03 and Kappa=0.547. Re-performance of D-S PLUS staging presented the following results: New method, McNemar test, P=0.317 and Kappa=0.93; for the routine method, McNemar test, P=0.223 and Kappa=0.811. These findings indicated that the CT component of PET/CT could improve the concordance with MRI results in the assessment of DI, and the same results were obtained when D-S PLUS staging was performed. The CT in PET/CT can enhance diagnostic accuracy in the assessment of DI by reducing the false negatives when compared with the routine ¹⁸F-FDG method.

Cardiac tamponade in multiple myeloma - A pictorial case review of FDG PET/CT findings

Pericardial involvement of multiple myeloma is a rare and late-stage complication, with only a few cases reported in the literature. PET/CT has demonstrated a growing role in the diagnosis and follow-up of patients with multiple myeloma. We present a case of pericardial multiple myeloma in a patient with relapsed/refractory disease, showcasing previously unpublished FDG PET/CT findings.

Diagnosis of spinal lesions using perfusion parameters measured by DCE-MRI and metabolism parameters measured by PET/CT

PURPOSE

To investigate the correlation of parameters measured by dynamic-contrast-enhanced MRI (DCE-MRI) and ¹⁸F-FDG PET/CT in spinal tumors, and their role in differential diagnosis.

METHODS

A total of 49 patients with pathologically confirmed spinal tumors, including 38 malignant, six benign and five borderline tumors, were analyzed. The MRI and PET/CT were done within 3 days, before biopsy. On MRI, the ROI was manually placed on area showing the strongest enhancement to measure pharmacokinetic parameters K^trans and k_ep. On PET, the maximum standardized uptake value SUV_max was measured. The parameters in different histological groups were compared. ROC was performed to differentiate between the two largest subtypes, metastases and plasmacytomas. Spearman rank correlation was performed to compare DCE-MRI and PET/CT parameters.

RESULTS

The K^trans, k_ep and SUV_max were not statistically different among malignant, benign and borderline groups (P = 0.95, 0.50, 0.11). There was no significant correlation between K^trans and SUV_max (r = - 0.20, P = 0.18), or between k_ep and SUV_max (r = - 0.16, P = 0.28). The k_ep was significantly higher in plasmacytoma than in metastasis (0.78 ± 0.17 vs. 0.61 ± 0.18, P = 0.02); in contrast, the SUV_max was significantly lower in plasmacytoma than in metastasis (5.58 ± 2.16 vs. 9.37 ± 4.26, P = 0.03). In differential diagnosis, the AUC of k_ep and SUV_max was 0.79 and 0.78, respectively.

CONCLUSIONS

The vascular parameters measured by DCE-MRI and glucose metabolism measured by PET/CT from the most aggressive tumor area did not show a significant correlation. The results suggest they provide complementary information reflecting different aspects of the tumor, which may aid in diagnosis of spinal lesions. These slides can be retrieved under Electronic Supplementary Material.

PET with Fluorodeoxyglucose F 18/Computed Tomography as a Staging Tool in Multiple Myeloma

In the past decade novel treatment options have dramatically prolonged the survival of patients with multiple myeloma. PET combined with computed tomography (CT) is a sensitive and reliable functional imaging tool that enables diagnosis and assessment of response to chemotherapy/radiotherapy, and combines high sensitivity in identifying both lytic lesions and extramedullary soft-tissue masses with the ability to provide reliable prognostic information in the management of patients with myeloma. This review comprises a comprehensive overview of PET with fluorodeoxyglucose F 18/CT imaging in combination with other convenient imaging procedures, and attempts at standardization with emphasis on post-therapy findings in patients with myeloma.

Interest of Pet Imaging in Multiple Myeloma

The interest of 18Fluoro-deoxyglucose (FDG) positron emission tomography (PET) imaging in the management of patients with multiple myeloma (MM) for the workup at diagnosis and for therapeutic evaluation has recently been demonstrated. FDG-PET is a powerful imaging tool for bone lesions detection at initial diagnosis with high sensitivity and specificity values. The independent pejorative prognostic value on progression-free survival (PFS) and overall survival (OS) of baseline PET-derived parameters (presence of extra-medullary disease (EMD), number of focal bone lesions (FLs), and maximum standardized uptake values [SUV_max]) has been reported in several large independent prospective studies. During therapeutic evaluation, FDG-PET is considered as the reference imaging technique, because it can be performed much earlier than MRI which lacks specificity. Persistence of significant FDG uptake after treatment, notably before maintenance therapy, is an independent pejorative prognostic factor, especially for patients with a complete biological response. So FDG-PET and medullary flow cytometry are complementary tools for detection of minimal residual disease before maintenance therapy. However, the definition of PET metabolic complete response should be standardized. In patients with smoldering multiple myeloma, the presence of at least one hyper-metabolic lytic lesions on FDG-PET may be considered as a criterion for initiating therapy. FDG-PET is also indicated for initial staging of a solitary plasmacytoma so as to not disregard other bone or extra-medullary localizations. Development of nuclear medicine offer new perspectives for MM imaging. Recent PET tracers are willing to overcome limitations of FDG. (11)C-Methionine, which uptake reflects the increased protein synthesis of malignant cells seems to correlate well with bone marrow infiltration. Lipid tracers, such as Choline or acetate, and some peptide tracers, such as (68) Ga-Pentixafor, that targets CXCR4 (chemokine receptor-4, which is often expressed with high density by myeloma cells), are other promising PET ligands. 18F-fludarabine and immuno-PET targeting CD138 and CD38 also showed promising results in preclinical models.

CD38-Driven Mitochondrial Trafficking Promotes Bioenergetic Plasticity in Multiple Myeloma

Metabolic adjustments are necessary for the initiation, proliferation, and spread of cancer cells. Although mitochondria have been shown to move to cancer cells from their microenvironment, the metabolic consequences of this phenomenon have yet to be fully elucidated. Here, we report that multiple myeloma cells use mitochondrial-based metabolism as well as glycolysis when located within the bone marrow microenvironment. The reliance of multiple myeloma cells on oxidative phosphorylation was caused by intercellular mitochondrial transfer to multiple myeloma cells from neighboring nonmalignant bone marrow stromal cells. This mitochondrial transfer occurred through tumor-derived tunneling nanotubes (TNT). Moreover, shRNA-mediated knockdown of CD38 inhibits mitochondrial transfer and TNT formation in vitro and blocks mitochondrial transfer and improves animal survival in vivo. This study describes a potential treatment strategy to inhibit mitochondrial transfer for clinical benefit and scientifically expands the understanding of the functional effects of mitochondrial transfer on tumor metabolism. SIGNIFICANCE: Multiple myeloma relies on both oxidative phosphorylation and glycolysis following acquisition of mitochondria from its bone marrow microenvironment.See related commentary by Boise and Shanmugam, p. 2102.

Triply Loaded Nitroxide Brush-Arm Star Polymers Enable Metal-Free Millimetric Tumor Detection by Magnetic Resonance Imaging

Nitroxides occupy a privileged position among plausible metal-free magnetic resonance imaging (MRI) contrast agents (CAs) due to their inherently low-toxicity profiles; nevertheless, their translational development has been hindered by a lack of appropriate contrast sensitivity. Nanostructured materials with high nitroxide densities, where each individual nitroxide within a macromolecular construct contributes to the image contrast, could address this limitation, but the synthesis of such materials remains challenging. Here, we report a modular and scalable synthetic approach to nitroxide-based brush-arm star polymer (BASP) organic radical CAs (ORCAs) with high nitroxide loadings. The optimized ∼30 nm diameter "BASP-ORCA3" displays outstanding T2 sensitivity with a very high molecular transverse relaxivity ( r2 > 1000 mM-1 s-1). BASP-ORCA3 further exhibits excellent stability in vivo, no acute toxicity, and highly desirable pharmacokinetic and biodistribution profiles for longitudinal detection of tumors by MRI. When injected intravenously into mice bearing subcutaneous plasmacytomas, BASP-ORCA3 affords distinct in vivo visualization of tumors on translationally relevant time scales. Leveraging its high sensitivity, BASP-ORCA3 enables efficient mapping of tumor necrosis, which is an important biomarker to predict therapeutic outcomes. Moreover, BASP-ORCA3 allows for detection of millimetric tumor implants in a disseminated murine model of advanced-stage human ovarian cancer that possess genetic, histological, and vascular characteristics that are similar to those seen in patients. This work establishes BASP-ORCA3 as a promising metal-free spin contrast agent for MRI.

18F-FDG PET/CT is useful for determining survival outcomes of patients with multiple myeloma classified as stage II and III with the Revised International Staging System

PURPOSE

This study evaluated the prognostic role of ¹⁸F-FDG PET/CT at baseline in patients with newly diagnosed multiple myeloa (MM) and evaluated the prognostic relevance of ¹⁸F-FDG PET/CT for each stage according to the Revised International Staging System (R-ISS).

METHOD

We retrospectively analyzed the records of 167 patients with newly diagnosed MM. ¹⁸F-FDG PET/CT was performed prior to induction therapy in patients with newly diagnosed MM.

RESULTS

In the total cohort, the presence of more than three hypermetabolic focal lesions (FLs) or extramedullary disease (EMD) on baseline PET/CT was associated with significantly inferior progression-free survival (PFS) and overall survival (OS) than other patients. Because most patients (91%) with EMD had more than three FLs, PET/CT positivity was defined as the presence of more than three FLs or the presence of EMD. In multivariate analyses, PET/CT positivity was an independent predictor of PFS and OS in all patients. Fifty-five patients (46.1%) with R-ISS II were PET/CT-positive at baseline and had significantly shorter PFS and OS. PET/CT positivity was also correlated with poor PFS and OS in patients with R-ISS III.

CONCLUSION

¹⁸F-FDG PET/CT was an independent predictor of survival outcomes in patients with newly diagnosed MM. In addition, performing ¹⁸F- FDG PET/CT at diagnosis may be useful for determining the survival outcomes of MM patients with R-ISS II and III.

Applications of PET/CT and PET/MR Imaging in Primary Bone Malignancies

Primary bone malignancies are characterized with anatomic imaging. However, in recent years, there has been an increased interest in PET/computed tomography scanning and PET/MRI with fludeoxyglucose F 18 for evaluating and staging musculoskeletal neoplasms. These hybrid imaging modalities have shown promise largely owing to their high sensitivity, ability to perform more thorough staging, and ability to monitor treatment response. This article reviews the current role of PET/computed tomography scanning and PET/MRI in primary malignancies of bone, with an emphasis on imaging characteristics, clinical usefulness, and current limitations.

Prognostic significance of normalized FDG-PET parameters in patients with multiple myeloma undergoing induction chemotherapy and autologous hematopoietic stem cell transplantation: a retrospective single-center evaluation

PURPOSE

The purpose of this study was to determine retrospectively, through a single-center evaluation, whether FDG PET-CT normalized semi-quantitative parameters may predict response to induction chemotherapy (iChT) and hematopoietic stem cell transplantation (HSCT), as well as disease progression and progression-free survival in multiple myeloma (MM) patients, thus becoming a tool of personalized medicine.

METHODS

Patients undergoing iChT and HSCT with baseline and post-treatment FDG PET-CTs from January 2008 to July 2015 were included. The following baseline and post-treatment parameters were obtained: SUVmax, SUVmean, SUVpeak, MTVsum, TLGsum, rPET (lesion SUVmax/liver SUVmax) and qPET (lesion SUVpeak/liver SUVmean). Baseline-to-post-treatment changes (Δ) were also calculated. Metabolic and clinical laboratory progression or response at follow-up were noted; time-to-metabolic-progression (TMP) was defined as the interval from post-treatment scan to eventual progression at follow-up FDG PET-CTs. Possible association between each functional parameter and metabolic/clinical-laboratory progression or response was determined. Kaplan-Meier curves allowed to depict the TMP trend according to FDG PET-CT parameters.

RESULTS

Twenty-eight patients were included. Significantly higher ΔrPET and ΔqPET values were observed in ten patients with "metabolic response", with respect to 18 patients having "metabolic progression" (median 0.62 [IQR 0.32 - 1.34] vs median 0.00 [IQR -0.25 - 0.49] for ΔrPET; P = 0.045; median 0.51 [IQR 0.32 - 1.13] vs median 0.00 [IQR -0.31 - 0.67] for ΔqPET; P = 0.035). Neither normalized nor non normalized parameters differed significantly between the 20 patients with "clinical-laboratory response" and the eight patients with "clinical-laboratory progression". ΔrPET value lower than 0.38 and ΔqPET value lower than 0.27 predicted a significantly shorter TMP (P = 0.003 and P = 0.005, respectively).

CONCLUSIONS

Normalized semi-quantitative parameters are effective in predicting persistent response to treatment and shorter TMP in patients with MM undergoing iChT and HSCT.

Nuclear Medicine Imaging in the Dentomaxillofacial Region

Nuclear medicine studies evaluate physiology on a molecular level providing earlier detection of lesions before morphologic change is evident. ^99mTc-MDP and ¹⁸F-fluoride bone scans detect osteomyelitis earlier than radiographs and computed tomography (CT); aid in diagnosis of temporomandibular joint disorder; and evaluate activity of condylar hyperplasia, extent of Paget disease, and viability of bone grafts. ¹⁸F-FDG PET/CT distinguish between soft tissue and bone infections and diagnose osteomyelitis complicated by fracture or surgery. FDG PET is more accurate than CT alone and has a major role in staging, restaging, and assessing response to therapy for head and neck malignancies and in detecting sequelae of therapy.

Correlation Between Baseline 18F-FDG PET/CT Findings and CD38- and CD138-Expressing Myeloma Cells in Bone Marrow and Clinical Parameters in Patients with Multiple Myeloma

Objective

The aim of this study was to evaluate the relation between the rate of fluorine-18 (18F) fludeoxyglucose (FDG) uptake and CD38 and CD138 expression in myeloma cells in bone marrow and other clinical parameters in patients with multiple myeloma (MM).

Materials and Methods

Patients with the diagnosis of MM who underwent 18F-FDG positron emission tomography/computed tomography (PET/CT) for initial staging were evaluated retrospectively. We analyzed a total of 42 patients (43-83 years old, mean: 64.4±9.9). Hematological and biochemical tests including hemoglobin, hematocrit, C-reactive protein, β2-microglobulin, creatinine, albumin, calcium, lactate dehydrogenase, and erythrocyte sedimentation rate were recorded. In bone marrow samples, plasma cell ratio and CD38 and CD138 immunohistochemical staining were evaluated. On PET/CT images, mean standardized uptake values (SUV_mean) of the right anterior and posterior iliac crest and right proximal femora were calculated. The correlations between the average SUV_mean of bone marrow and CD38- and CD138-expressing myeloma cells and other parameters were analyzed by Spearman’s correlation test. Values of p<0.05 were considered statistically significant.

Results

Types of MM were IgG_K (45%), IgG_L (21%), IgA_K (7%), IgA_L (10%), and others (17%). Thirty-two (76%) patients were at stage III according to the Salmon-Durie staging system. There was a statistically significant positive correlation between bone marrow FDG uptake and percentage of plasma cells in bone marrow and CD38 and CD138 expression in plasma cells (r=0.403, r=0.339, and r=0.409) and β2-microglobulin and C-reactive protein levels (r=0.676, r=0.541). There was a negative correlation between bone marrow FDG uptake and hemoglobin and hematocrit values (r=-0.377 and r=-0.368). Other hematological parameters were not correlated with FDG uptake in bone marrow.

Conclusion

Increased FDG uptake is correlated with the percentage of CD38 and CD138 expression in plasma cells in bone marrow. In addition to initial staging, 18F-FDG PET/CT is useful in treatment planning and prognostic evaluation in MM patients.

Is 99m Tc-methylene diphosphonate bone scintigraphy a sensitive method for detecting bone lesions in multiple myeloma?

Background

Bone lesion in multiple myeloma (MM) is most commonly presented as a lytic lesion in this disease. Determination of extent of bone lesions in MM is necessary to follow-up the patients. Whole body bone scan with 99m, Tc-methylene diphosphonate (MDP) has a lower sensitivity than other modalities.

Methods

From the patients with MM admitted to Ayatollah Rouhani Hospital of Babol-Iran from 2009 to 2015, who had undergone whole body bone scan during diagnostic process, were entered into the study. Findings of bone scan were compared with MRI.

Results

Of the 19 patients, sixteen (84.2%) of them had positive finding in bone scan, fifteen (78.9%) had MRI of the spine. While of the thirteen patients who had positive finding in MRI, seven (53.8%) had more positive finding in thorcolumbosacral MRI than in bone scan.

Conclusions

99m-Tc MDP bone scan is a sensitive but insufficient method for detecting bone lesions in MM.

Established and Novel Prognostic Biomarkers in Multiple Myeloma

Multiple myeloma (MM) is an incurable plasma cell malignancy characterized by notable interpatient heterogeneity. There have been important advances in therapy and overall survival, but some patients with high-risk features still have poor survival rates. Therefore, accurate identification of this subset of patients has been integral to improvement of patient outcome. During the last few years, cytogenetics, gene expression profiling, MRI and PET/CT, as well as serum free light chain assays have been used as accurate biomarkers to better characterize the diverse course and outcome of the disease. With the recent advances of massive parallel sequencing techniques, the development of new models that better stratify high-risk groups are beginning to be developed. The use of multiparameter flow cytometry and next-generation sequencing have paved the way for assessment of minimal residual disease and better prognostication of post-therapeutic outcomes. Circulating tumor cells and circulating tumor DNA are promising potential biomarkers that demonstrate the spatial and temporal heterogeneity of MM. Finally, more prognostic markers are being developed that are specific to immunotherapeutic agents. In this review, we discuss these traditional and novel biomarkers that have been developed for MM and also those that can predict disease progression from precursor stages. Together, these biomarkers will help improve our understanding of the intrapatient and interpatient variabilities and help develop precision medicine for patients with high-risk MM.

The Critical Role of Imaging in the Management of Multiple Myeloma

Multiple myeloma (MM) is characterized by abnormal proliferation of plasma cells in the bone marrow leading to symptoms of anemia, renal failure, hypercalcemia, and bone lesions. Bone imaging is critical for the diagnosis, staging, assessment for the presence and extent of bone lesions, and initial treatment of MM. Skeletal survey is the preferred initial imaging modality due to its availability and low cost. However, it has poor sensitivity and patients with occult myeloma may escape detection, delaying their diagnosis and treatment. New cross-sectional imaging modalities such as low-dose whole body CT, MRI, and PET-CT have high sensitivity and specificity for detecting lytic lesions and extramedullary relapse in MM. The combined use of cross-sectional imaging may provide complimentary information for staging, prognosis, and disease monitoring. In this review, we will discuss commonly used imaging modalities and their advantages and disadvantages in the management of MM.

Minimal residual disease analysis in myeloma - when, why and where

The primary hurdle in the path to curing multiple myeloma (MM) is defining a validated minimal residual disease (MRD) and its utility in the therapeutic decision making. A better definition of MRD will aid in tailoring MM therapy further to address the clonal heterogeneity and genomic instability and overcome patient's ineffective immune surveillance. MRD analysis can define the logical endpoint for maintenance therapy, in addition also aids in providing a better clinical end point for studies comparing novel agents in myeloma. MRD is a surrogate for the survival in MM. Guidelines for global incorporation of MRD in myeloma are fraught with lack of standardization, universal availability and abridged physicians' understanding of MRD modalities. We aimed at addressing some of the frequently asked questions in the MRD assessment and will also place in perspective some arguments in favor of MRD assessment in routine practice and clinical trial scenario.

Doxycycline treatment in dialysis related amyloidosis: discrepancy between antalgic effect and inflammation, studied with FDG-positron emission tomography: a case report

Background

No effective treatment is currently available and dialysis related amyloidosis continues to be invalidating in long-term dialysis patients. A recent case series reported reduction of osteoarticular pain on doxycycline treatment, extending the indications of this drug, used in other uncommon forms of amyloidosis, to dialysis patients. Explanations of the antalgic effect were the anti-inflammatory properties and anti-coiling effects of tetracycline.

Case presentation

Our report regards a 54-year-old woman, who was never transplanted and has been on hemodialysis and hemodiafiltration for overall 37 years, due to renal hypoplasia. In spite of high efficiency hemodiafiltration, she complained of increasing, invalidating osteoarticular pain; history and imaging suggested beta-2 microglobulin amyloid. Positron emission tomography (PET scan) identified metabolically active lesions in the involved settings. Low-dose doxycycline (100 mg/day) was started, leading to a considerable decrease in pain (over 6 months, from 7 to 8 to 4–5 on a 0–10 scale). At 6 months, a PET scan showed unmodified or increased uptake in the involved settings.

Conclusions

In summary, the previously described antalgic effect of doxycycline in dialysis related amyloidosis is confirmed in our case, the first studied using PET scan. The pattern at PET can suggests that the antalgic effect is independent from inflammation and points to other factors, such as interaction with fibril geometry or with bone structure.

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.

Extramedullary Solitary Plasmacytoma: Demonstrating the Role of 18F-FDG PET Imaging

An Extramedullary Plasmacytoma (EMP) is characterized by a neoplastic proliferation of clonal plasma cells outside the medullary cavity. EMPs are a rare occurrence compared to other malignant plasma cell disorders and account for approximately 3-5% of plasma-cell neoplasms. Although most cases of EMP are not immediately life threatening at diagnosis, EMPs can progress to Multiple Myeloma (MM) and thus, warrant monitoring. Currently, there are no standard guidelines for when and how to monitor patients who are diagnosed with or treated for a solitary plasmacytoma. We present a case of solitary EMP who was treated adequately and definitively but developed a distinct, non-contiguous subsequent solitary EMP and was only discovered due to surveillance 18F-Fludeoxyglucose Positron Emission Tomography (18F-FDG) (PET) scan. Uniform surveillance guidelines should be developed and the potential benefits of PET and other imaging techniques as well as their cost should be considered.

Abdominal adipose tissue in MGUS and multiple myeloma

OBJECTIVE

To determine abdominal adipose tissue parameters on PET/CT in patients with monoclonal gammopathy of undetermined significance (MGUS) and multiple myeloma (MM) that may serve as predictors of progression of MGUS to MM. We hypothesized that patients with MM had higher abdominal adiposity and higher fat metabolic activity compared to patients with MGUS.

MATERIALS AND METHODS

Our retrospective study was IRB approved and HIPAA compliant. The study group comprised 40 patients (mean age 64 ± 13 years) with MGUS and 32 patients (mean age 62 ± 10 years) with recently diagnosed MM (mean time since diagnosis of MM 3.0 ± 3.9 months) who had not undergone MM treatment. All patients underwent whole body FDG-PET/CT. Total abdominal adipose tissue (TAT), abdominal subcutaneous adipose tissue (SAT) and visceral adipose tissue (VAT) cross sectional areas (CSA) (cm(2)) and metabolic activity (SUV) were assessed. Groups were compared using ANOVA. ROC curve analysis was performed to determine cutoff values for abdominal adipose tissue parameters to detect MM.

RESULTS

Patients with recently diagnosed MM had higher TAT and SAT CSA (p ≤ 0.03) and higher fat metabolic activity (p < 0.01). VAT metabolic activity showed the highest sensitivity and specificity for identifying patients with MM (area under the curve 0.95 with cutoff value of >0.34, sensitivity 90.6 %, specificity 92.5 %, p < 0.0001).

CONCLUSIONS

Patients who were recently diagnosed with MM had higher abdominal fat CSA and higher fat metabolic activity compared to patients with MGUS. These parameters may serve as novel biomarkers of progression of MGUS to MM.