99mTc-sestamibi SPECT/CT and 18F-FDG-PET/CT have similar performance but different imaging patterns in newly diagnosed multiple myeloma

Head-to-head comparison of [68Ga]Ga-PSMA-11 and [18F]FDG PET/CT in multiple myeloma

PURPOSE

The aim of this study was to compare [18F]FDG and [68Ga]Ga-PSMA-11 PET/CT image findings in patients with multiple myeloma (MM).

METHODS

Twenty consecutive patients with symptomatic biopsy-proven MM were submitted to whole body [18F]FDG and [68Ga]Ga-PSMA-11 PET/CT with a time interval of 1-8 days between procedures. All lesions were counted and had their maximum SUV (SUVmax) measured. Intra-class correlation (ICC) was used to assess the agreement between [18F]FDG and [68Ga]Ga-PSMA-11 PET/CT findings.

RESULTS

A total of 266 lesions were detected in 19/20 patients. [18F]FDG detected 223/266 (84%) lesions in 17 patients and [68Ga]Ga-PSMA-11 190/266 (71%) lesions in 19 patients. Both procedures did not identify any active lesion in 1 patient. Forty-three (16%) lesions were detected only by [68Ga]Ga-PSMA-11 and 76 (29%) only by [18F]FDG. Both tracers identified 147 (55%) lesions. Intralesional mismatch of FDG-PSMA uptake was identified in 25 of these 147 lesions, found in 8 different patients. Different lesions with uptake of only [18F]FDG or [68Ga]Ga-PSMA-11 in the same patient were found in 4 patients. The highest SUVmax of [18F]FDG and [68Ga]Ga-PSMA-11 had a median (min-max) SUVmax of 6.5 (2.0-37.8) and 5.5 (1.7-51.3), respectively. [18F]FDG and [68Ga]Ga-PSMA-11 respectively identified 18 and 19 soft tissue lesions. False-positive [18F]FDG findings had minimal or no uptake of [68Ga]Ga-PSMA-11. Good reliability (ICC ≥ 0.75) was found for number of lesions, number of soft tissue lesions and highest SUVmax in each patient.

CONCLUSION

[18F]FDG or [68Ga]Ga-PSMA-11 alone can detect most MM lesions. Almost half of the lesions take up only one of the tracers, reflecting increased glycolysis or angiogenesis in specific lesions, and suggesting their possible complementary role in MM. The marked [68Ga]Ga-PSMA-11 uptake in some cases raises the possibility of a theranostic approach in selected patients.

Molecular Imaging Diagnosis of Renal Cancer Using 99mTc-Sestamibi SPECT/CT and Girentuximab PET-CT-Current Evidence and Future Development of Novel Techniques

Novel molecular imaging opportunities to preoperatively diagnose renal cell carcinoma is under development and will add more value in limiting the postoperative renal function loss and morbidity. We aimed to comprehensively review the research on single photon emission computed tomography/computed tomography (SPECT/CT) and positron emission tomography computed tomography (PET-CT) molecular imaging and to enhance the urologists' and radiologists' knowledge of the current research pattern. We identified an increase in prospective and also retrospective studies that researched to distinguish between benign and malignant lesions and between different clear cell renal cell carcinoma subtypes, with small numbers of patients studied, nonetheless with excellent results on specificity, sensitivity and accuracy, especially for ^99mTc-sestamibi SPECT/CT that delivers quick results compared to a long acquisition time for girentuximab PET-CT, which instead gives better image quality. Nuclear medicine has helped clinicians in evaluating primary and secondary lesions, and has lately returned with new and exciting insights with novel radiotracers to reinforce its diagnostic potential in renal carcinoma. To further limit the renal function loss and post-surgery morbidity, future research is mandatory to validate the results and to clinically implement the diagnostic techniques in the context of precision medicine.

SPECT/CT and PET/CT, related radiopharmaceuticals, and areas of application and comparison

The paper begins by identifying the key historical elements in the development of nuclear medicine imaging, focusing on the Anger camera and single photon emission computed tomography (SPECT) technologies. In this context, key reference is made to the physics of detection in Anger camera systems, especially key components such as the sodium iodide crystal, the function and performance of photomultiplier tubes, and the collimator design. It is discovered that within each component of technology, there are fundamental physical relationships that govern the performance of each component, and that overall image quality is the result of the complex interaction of all such elements. The increasing use of SPECT/CT imaging is described and illustrated with a range of typical clinical applications, which include brain, spinal, cardiac, and cancer studies. The use of CT imaging functionality allows for SPECT image correction based on compensation for absorption within tissue. Reference is also made to the basics of positron emission tomography (PET) imaging and, in particular, to the integration of PET/CT systems where the anatomy profile of the CT image is used to provide correction for photon absorption. A summary is provided of the radionuclides and radiopharmaceuticals commonly used in PET/CT imaging and a range of image studies referenced includes those of nasopharyngeal carcinoma, lung cancer investigation, brain investigation (cancer detection and dementia) and cardiac function. Reference is made to the development of "time of flight" (TOF) technology for improving of image resolution in PET/CT systems. Furthermore, SPECT/CT and PET/CT imaging systems are compared, where a key factor identified is the significantly higher number of photons detected with PET/CT technology and improved image resolution.

Solitary hyoid plasmacytoma with unicentric Castleman disease: A case report and review of literature

BACKGROUND

Solitary plasmacytoma and unicentric Castleman disease (UCD) are rare lymphoproliferative disorders characterized by monoclonal plasma cells and a single set of locally enlarged lymph nodes, respectively.

CASE SUMMARY

A 48-year-old Han Chinese man presented to our department with a neck mass and progressive foreign body sensation in his throat. ¹⁸F-FDG positron emission tomography revealed focally increased radioactivity centered around the hyoid, and computed tomography (CT) revealed osteolytic lesions. Histopathology revealed Castleman-like features and CD138/CD38-positive mature plasma cells. Systemic work-up ruled out the possibility of POEMS syndrome, lymphoma, and multiple myeloma, leading to a final diagnosis of solitary hyoid plasmacytoma with UCD. The patient underwent partial hyoid resection and selective neck dissection, followed by intensity-modulated radiotherapy. 99mTc-MDP single-photon emission computed tomography/CT reevaluation showed neither local recurrence nor distant bone metastasis at the 40-mo follow-up.

CONCLUSION

The diagnostic process and differential diagnosis of this rare case provided valuable educational information to clinicians.

Recent developments on the application of molecular probes in multiple myeloma: Beyond [18F]FDG

Multiple myeloma (MM) is a neoplastic plasma cell proliferative disorder characterized by various osteolytic bone destruction as a radiological morphological marker. Functional imaging, particularly nuclear medicine imaging, is a promising method to visualize disease processes before the appearance of structural changes by targeting specific biomarkers related to metabolism ability, tumor microenvironment as well as neoplastic receptors. In addition, by targeting particular antigens with therapeutic antibodies, immuno-PET imaging can support the development of personalized theranostics. At present, various imaging agents have been prepared and evaluated in MM at preclinical and clinical levels. A summary overview of molecular functional imaging in MM is provided, and commonly used radiotracers are characterized.

Myeloma Spine and Bone Damage Score (MSBDS) on Whole-Body Computed Tomography (WBCT): Multiple Reader Agreement in a Multicenter Reliability Study

Objective: To assess the reliability of the myeloma spine and bone damage score (MSBDS) across multiple readers with different levels of expertise and from different institutions. Methods: A reliability exercise, including 104 data sets of static images and complete CT examinations of patients affected by multiple myeloma (MM), was performed. A complementary imaging atlas provided detailed examples of the MSBDS scores, including low-risk and high-risk lesions. A total of 15 readers testing the MSBDS were evaluated. ICC estimates and their 95% confidence intervals were calculated based on mean rating (k = 15), absolute agreement, a two-way random-effects model and Cronbach's alpha. Results: Overall, the ICC correlation coefficient was 0.87 (95% confidence interval: 0.79-0.92), and the Cronbach's alpha was 0.93 (95% confidence interval: 0.94-0.97). Global inter- and intra-observer agreement among the 15 readers with scores below or equal to 6 points and scores above 6 points were 0.81 (95% C.I.: 0.72-0.86) and 0.94 (95% C.I.:0.91-0.98), respectively. Conclusion: We present a consensus-based semiquantitative scoring systems for CT in MM with a complementary CT imaging atlas including detailed examples of relevant scoring techniques. We found substantial agreement among readers with different levels of experience, thereby supporting the role of the MSBDS for possible large-scale applications. Significance and Innovations • Based on previous work and definitions of the MSBDS, we present real-life reliability data for quantitative bone damage assessment in multiple myeloma (MM) patients on CT. • In this study, reliability for the MSBDS, which was tested on 15 readers with different levels of expertise and from different institutions, was shown to be moderate to excellent. • The complementary CT imaging atlas is expected to enhance unified interpretations of the MSBDS between different professionals dealing with MM patients in their routine clinical practice.

Multimodality Molecular Imaging in Arthropathy Associated with Multiple Myeloma

We report a patient with multiple myeloma (MM) and polyarthritis of large joints. During the staging of the disease, bone marrow diffusely involved by MM was clearly demonstrated by 99mTc-2-methoxy-isobutyl-isonitrile (MIBI) single-photon emission computed tomography/computed tomography (SPECT/CT) but not by 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography/CT images. On the other hand, a very intense uptake of 18F-FDG was detected in periarticular tissues of multiple joints, with nonabnormal 99mTc-MIBI accumulation. Rheumatology tests were negative. A subsequent bone scintigraphy demonstrated radiolabeled bisphosphonate accumulation in periarticular tissues, suggesting amyloid arthropathy.

Metabolic Volume Measurements in Multiple Myeloma

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