Is fluorine-18-fluorodeoxyglucose positron emission tomography useful in monitoring the response to treatment in patients with multiple myeloma?

Molecular imaging of endocrine neoplasms with emphasis on 18F-DOPA PET: a practical approach for well-tailored imaging protocols

6-[18F]-L-fluoro-L-3, 4-dihydroxyphenylalanine (¹⁸F-DOPA) PET/CT can be a useful tool for the detection of different neuroendocrine tumors (NETs). The main determinants of ¹⁸F-DOPA uptake and retention by NETs are related to expression of LAT1/LAT2 transporters, expression and activity of AADC and biochemical phenotype, all being intimately inter-connected to their embryological origin. In order to improve sensitivity of ¹⁸F-DOPA PET, it is of main importance to perform indivisualized imaging protocols across primaries. This review provides a practical approach for performing well-tailored imaging protocols and describes the clinical value of the recommended radiopharmaceuticals.

Prospective Comparison of 18-FDG PET/CT and Whole-Body MRI with Diffusion-Weighted Imaging in the Evaluation of Treatment Response of Multiple Myeloma Patients Eligible for Autologous Stem Cell Transplant

To compare the prognostic values of 18-FDG PET/CT (FDG-PET) and Whole-Body MRI with Diffusion-Weighted Imaging (WB-DW-MRI) in the evaluation of treatment response of Multiple Myeloma (MM) patients eligible for ASCT. Thirty patients with newly diagnosed MM prospectively underwent FDG-PET and WB-DW-MRI at baseline, after induction chemotherapy and after ASCT. Response on WB-DW-MRI was evaluated with the MY-RADS criteria. FDG-PET was considered positive if residual uptake was superior to liver uptake. Imaging results were not used for treatment modification. The impact of imaging results on PFS was analyzed. After a median follow-up of 32 months, 10 patients relapsed. With WB-DW-MRI, post-induction examination was positive in 3/25 and post-ASCT examination was positive in 3/27 patients. However, neither study showed prognostic impact on PFS. FDG-PET was positive in 5/22 post-induction and 3/26 patients post-ASCT, respectively. Positivity of FDG-PET, post-induction or post-ASCT, was associated with a shorter PFS (post-induction: median PFS 19 months vs. not reached, log-rank p = 0.0089; post-ASCT: median PFS 18 months vs. not reached, log-rank p = 0.0005). Preliminary results from this small, single-center, prospective study show that, whether performed post-induction or post-ASCT, FDG-PET has a higher prognostic value than WB-DW-MRI for treatment response evaluation of newly diagnosed MM.

Semi-quantitative analysis of 18F fluorodeoxyglucose uptake in the assessment of disease activity and therapeutic response in rheumatoid arthritis: An institutional experience

¹⁸F fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography (PET) can be used to image synovial inflammation in patients with rheumatoid arthritis (RA). Recently, clinical application of novel therapies for RA, such as tumor necrosis factor-α (TNF-α) inhibitor and anti-interleukin-6 receptor antibody, has been introduced. The radiological assessment of disease activity changes of patients who underwent these therapies will help the clinicians to obtain more information about the patients and to decide drug withdrawal or change of medication. It is considered that ¹⁸F-FDG PET scan is generally very expensive; however, the information from ¹⁸F-FDG PET about patients during biological treatments helps discontinuation of these treatments with incomplete response despite its high costs and with possible side effects such as malignant lymphoma. In this study, we evaluated if the 18F-FDG uptake of the affected joints represented by standardized uptake value (SUV) correlated with the clinical assessment of patients with RA. In addition, we would like to evaluate if there was a correlation between the difference of SUV and improvement of clinical findings in RA patients undergoing anti TNF therapies. RA patients who underwent anti-TNFα therapies in a tertiary care hospital were assessed using whole-body ¹⁸F-FDG PET/computed tomography (CT). PET assessments were performed on hip joints, knees, shoulders, wrists, ankles, MCP, and PIP for a total of 28 joints in each patient. The ¹⁸F-FDG uptake was then quantified using the maximum SUV (SUVmax) prior to, and 6 months after the initiation of treatment with anti-TNF-α drugs. Disease activity score (DAS28 and DAS28-C-reactive protein [CRP]) were recorded and white blood cell, matrix metalloproteinases (MMP-3) and rheumatoid factor (RF) were examined in all patients. The average of SUV_max among measured joints, or the sum of these joints (total SUV_max), correlated with DAS28 (r = 0.671, P < 0.001), DAS28-CRP (r = 0.623, P < 0.001), ESR (r = 0.542, P < 0.001), CRP (r = 0.411, P = 0.002), MMP-3 (r = 0.399, P = 0.006), and RF (r = 0.447, P = 0.002). There were correlations between ΔSUV and ΔDAS28 (r = 0.651, P < 0.001), ΔSUV and ΔDAS28-CRP (r = 0.682, P < 0.001), ΔSUV and ΔESR (r = 0.449, P = 0.023), and ΔSUV and ΔMMP-3 (r = 0.457, P = 0.027), respectively. The number of PET-positive joints and the cumulative SUV significantly correlated with the DAS₂₈, which is a composite disease activity score (DAS) that combines the swollen and tender joint counts, the erythrocyte sedimentation rate (DAS₂₈-ESR) or CRP serum levels (DAS₂₈ - CRP) or RF (DAS₂₈ - RF) or metalloproteinases-3 (DAS_28-MMP-3). At baseline and at 6 months' post-treatment with anti-TNFα drugs, there was a significant correlation between the PET results, either visual, the cumulative SUVs or the composite SUV index, and the comprehensive clinical assessment (DAS₂₈), the CRP levels and the number of joints positive for RA, and cumulative synovial thickness. By reflecting inflammatory activity, ¹⁸F-FDG PET may enhance the diagnostic performance and expectation of disease prognosis in RA, especially with early synovial inflammation. The intensity of uptake varied from mild to intense (SUV_max values from 3.10 to 6.0). Overall, these values correlated well with the clinical evaluation of involved joints. ¹⁸F-FDG PET imaging data provided a distribution of joint involvement with varying degrees of severity and phase of disease activity (moderate, low, and remission) in the same patient. PET/CT imaging with ¹⁸F-FDG shows better image quality, provides more confirmative diagnostic information, and will be promising imaging modality in diagnosis and management of RA.

Correlation Between Uptake of 18F-FDG During PET/CT and Ki-67 Expression in Patients Newly Diagnosed With Multiple Myeloma Having Extramedullary Involvement

The aim of this study was to evaluate the relationship of prognosis of patients with multiple myeloma having extramedullary involvement (EMM) with the ¹⁸F- fluorodeoxyglucose(18F-FDG) maximum standardized uptake value and the expression of Ki-67 in biopsy samples. Sixty-five patients were newly diagnosed with multiple myeloma presenting with EMM at our hospital from January 2005 to January 2015. Of these 65 patients, 20 were enrolled in this study. Over the last decade, both the maximum standardized uptake value and Ki-67 expression in these extramedullary lesions significantly correlated with progression-free survival, respectively (P= .039, P =.009). After combining—the maximum standardized uptake value and the Ki-67 expression as an integral—there was a significant correlation between both the overall survival (P = .027) and progression-free survival (P= .014). Patients have poor outcomes when EMM is detected at presentation. Both the maximum standardized uptake value and Ki-67 expression could aid in accurately evaluating EMM patient prognosis.

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.

Simplified response monitoring criteria for multiple myeloma in patients undergoing therapy with novel agents using computed tomography

INTRODUCTION

Multiple myeloma is a malignant hematological disorder of the mature B-cell lymphocytes originating in the bone marrow. While therapy monitoring is still mainly based on laboratory biomarkers, the additional use of imaging has been advocated due to inaccuracies of serological biomarkers or in a-secretory myelomas. Non-enhanced CT and MRI have similar sensitivities for lesions in yellow marrow-rich bone marrow cavities with a favourable risk and cost-effectiveness profile of CT. Nevertheless, these methods are still limited by frequently high numbers of medullary lesions and its time consumption for proper evaluation.

OBJECTIVE

To establish simplified response criteria by correlating size and CT attenuation changes of medullary multiple myeloma lesions in the appendicular skeleton with the course of lytic bone lesions in the entire skeleton. Furthermore to evaluate these criteria with respect to established hematological myeloma-specific parameters for the prediction of treatment response to bortezomib or lenalidomide.

MATERIALS AND METHODS

Non-enhanced reduced-dose whole-body CT examinations of 78 consecutive patients (43 male, 35 female, mean age 63.69±9.2years) with stage III multiple myeloma were retrospectively re-evaluated. On per patient basis, size and mean CT attenuation of 2-4 representative lesions in the limbs were measured at baseline and at a follow-up after a mean of 8 months. Results were compared with the course of lytical bone lesions as well with that of specific hematological biomarkers. Myeloma response was assessed according to the International Myeloma Working Group (IMWG) uniform response criteria. Testing for correlation between response of medullary lesions (Resp_med) and response of all myeloma manifestations including osteolyses (Resp_total) was performed using the corrected contingency coefficient (C_corr).

RESULTS

The correlation between Resp_med based on length diameter and transverse diameter and Resp_total was perfect (C_corr=1.0; p<0.0001) whereas the correlation based on density was moderate (C_corr=0.54; p<0.0001). The evaluation of simplified response criteria with a measurement of only 2 medullary lesions yielded the best sensitivity and specificity valued for treatment-induced changes for the length diameter evaluation with 94.4%/95.7% for prediction of progressive disease and 78.6%/93.3% for prediction of therapy response. There were no significant differences between patients treated with bortezomib and lenalidomide (p>0.05).

CONCLUSION

Measurements of size of a minimum of two medullary lesions is sufficient for response assessment and correlates very well with the course of lytic bone lesions and that of hematologic parameters.

Pitfalls and Limitations of Radionuclide Planar and Hybrid Bone Imaging

The radionuclide (99m)Tc-MDP bone scan is one of the most commonly performed nuclear medicine studies and helps in the diagnosis of different pathologies relating to the musculoskeletal system. With its increasing utility in clinical practice, it becomes more important to be aware of various limitations of this imaging modality to avoid false interpretation. It is necessary to be able to recognize various technical, radiopharmaceutical, and patient-related artifacts that can occur while carrying out a bone scan. Furthermore, several normal variations of tracer uptake may mimic pathology and should be interpreted cautiously. There is an important limitation of a bone scan in metastatic disease evaluation as the inherent mechanism of tracer uptake is not specific for tumor but primarily relies on an osteoblastic response. Thus, it is crucial to keep in mind uptake in benign lesions, which can resemble malignant pathologies. The utility of a planar bone scan in benign orthopedic diseases, especially at sites with complex anatomy, is limited owing to lack of precise anatomical information. SPECT/CT has been significantly helpful in these cases. With wider use of PET/CT and reintroduction of the (18)F-fluoride bone scan, increasing knowledge of potential pitfalls on an (18)F-fluoride bone scan and (18)F-FDG-PET/CT will help in improving the accuracy of clinical reports.

11C-Acetate PET/CT Monitoring Therapy of Multiple Myeloma

A 67-year-old man with newly diagnosed multiple myeloma underwent both FDG and C-acetate PET/CT sequentially on different days. There was increased FDG activity only in L1 vertebral body, but there was diffuse abnormal C-acetate activity throughout the skeletal system. After the successful therapy, the patient who was on remission clinically underwent follow-up PET/CT scans. Interestingly, L1 remained to have elevated FDG, although with less intensity. In contrast, there was no abnormal C-acetate activity anywhere in the body. The patient remained in remission clinically.

State of the art imaging of multiple myeloma: comparative review of FDG PET/CT imaging in various clinical settings

18-Flurodeoxyglucose Positron Emission Tomography with computed tomography (FDG PET/CT) and Magnetic Resonance Imaging (MRI) have higher sensitivity and specificity than whole-body X-ray (WBXR) survey in evaluating disease extent in patients with multiple myeloma (MM). Both modalities are now recommended by the Durie-Salmon Plus classification although the emphasis is more on MRI than PET/CT. The presence of extra-medullary disease (EMD) as evaluated by PET/CT imaging, initial SUVmax and number of focal lesions (FL) are deemed to be strong prognostic parameters at staging. MRI remains the most sensitive technique for the detection of diffuse bone marrow involvement in both the pre and post-therapy setting. Compression fractures are best characterized with MRI signal changes, for determining vertebroplasty candidates. While PET/CT allows for earlier and more specific evaluation of therapeutic efficacy compared to MRI, when signal abnormalities persist years after treatment. PET/CT interpretation, however, can be challenging in the vertebral column and pelvis as well as in cases with post-therapy changes. Hence, a reading approach combining the high sensitivity of MRI and superior specificity of FDG PET/CT would be preferred to increase the diagnostic accuracy. In summary, the established management methods in MM, mainly relying on biological tumor parameters should be complemented with functional imaging data, both at staging and restaging for optimal management of MM.

Positron emission tomography image-guided drug delivery: current status and future perspectives

Positron emission tomography (PET) is an important modality in the field of molecular imaging, which is gradually impacting patient care by providing safe, fast, and reliable techniques that help to alter the course of patient care by revealing invasive, de facto procedures to be unnecessary or rendering them obsolete. Also, PET provides a key connection between the molecular mechanisms involved in the pathophysiology of disease and the according targeted therapies. Recently, PET imaging is also gaining ground in the field of drug delivery. Current drug delivery research is focused on developing novel drug delivery systems with emphasis on precise targeting, accurate dose delivery, and minimal toxicity in order to achieve maximum therapeutic efficacy. At the intersection between PET imaging and controlled drug delivery, interest has grown in combining both these paradigms into clinically effective formulations. PET image-guided drug delivery has great potential to revolutionize patient care by in vivo assessment of drug biodistribution and accumulation at the target site and real-time monitoring of the therapeutic outcome. The expected end point of this approach is to provide fundamental support for the optimization of innovative diagnostic and therapeutic strategies that could contribute to emerging concepts in the field of “personalized medicine”. This review focuses on the recent developments in PET image-guided drug delivery and discusses intriguing opportunities for future development. The preclinical data reported to date are quite promising, and it is evident that such strategies in cancer management hold promise for clinically translatable advances that can positively impact the overall diagnostic and therapeutic processes and result in enhanced quality of life for cancer patients.

Limited value of the international staging system for predicting long-term outcome of transplant-ineligible, newly diagnosed, symptomatic multiple myeloma in the era of novel agents

We retrospectively investigated clinical outcomes and prognostic factors of 131 patients with transplant-ineligible newly diagnosed multiple myeloma (NDMM) who received melphalan and prednisolone (MP) as first-line therapy from 2006 to 2013. Eighty-one patients received salvage therapies incorporating bortezomib, lenalidomide, and/or thalidomide. The overall response rate to MP was 54.2 %, including 9.2 % of better than very good partial response. With a median follow-up period of 30.2 months, median overall survival (OS) and median time to next treatment (TNT) were 54.4 and 19.0 months, respectively. Univariate analysis revealed that performance status and serum calcium level significantly associated with both OS and TNT, and multivariate analysis revealed that the higher serum calcium level had a significantly unfavorable impact on OS and TNT. Importantly, staging informed by the international staging system (ISS) was not predictive for OS or TNT in the analyzed cohort. Our study revealed that, in the context of first-line MP therapy for NDMM, the salvage therapy incorporating novel agents produced a survival period of >30 months after the initiation of second-line therapy, suggesting that the predictive value of ISS for OS and TNT may be limited in the era of novel agents.