Seminars in nuclear medicine最新文献

Infections of the bones and joints, if misdiagnosed, may result in serious morbidity and even mortality. A prompt diagnosis followed by appropriate management may reduce the socioeconomic impact of bone and joint infections. Morphologic imaging such as ultrasound and plain radiographs form the first line investigations, however, in early infections findings may be negative or nonspecific. Nuclear medicine imaging techniques play a complementary role to morphologic imaging in the diagnosis of bone and joint infections. The availability of hybrid systems (SPECT/CT, SPECT/MRI, PET/CT or PET/MRI) offers improved specificity with ability to assess the extent of infection. Bone scans are useful as a gatekeeper wherein negative scans rule out sepsis with a good accuracy, however positive scans are nondiagnostic and more specific tracers should be considered. These include the use of labeled white blood cells and antigranulocyte antibodies. Various qualitative and quantitative interpretation criteria have been suggested to improve the specificity of the scans. PET has better image resolution and ¹⁸F-FDG is the major tracer for PET imaging with applications in oncology and inflammatory/infective disorders. It has demonstrated improved sensitivity over the SPECT based tracers, however, still suffers from lack of specificity. ¹⁸F-FDG PET has been used to monitor therapy in bone and joint infections. Other less studied, noncommercialized SPECT and PET tracers such as ¹¹¹In-Biotin, ^99mTc-Ubiquicidin, ¹⁸F-Na-Fluoride, ¹⁸F-labeled white blood cells and ¹²⁴I-Fialuridine to name a few have shown great promise, however, their role in various bone and joint infections has not been established. Hybrid imaging with PET or PET/MRI offers huge potential for improving diagnostics in infections of the joints and bones.

Polymyalgia rheumatica (PMR) is an inflammatory disorder usually diagnosed in patients older than 50 years of age. It is characterized by sudden onset pain and prolonged morning stiffness in the scapular and/or pelvic girdle, sometimes debilitating and accompanied by constitutional symptoms such as weight loss. In approximately 20% of the cases, it is linked to giant cell arteritis (GCAV) representing a disease continuum. The diagnosis is mainly clinical and noninvasive imaging such as ultrasound of joints may be helpful. In atypical PMR cases, whole body imaging using [¹⁸F]FDG-PET/CT may be useful. First, to confirm or rule out the diagnosis of PMR, secondly, to assess the coexistence of a GCA, and thirdly to establish the differential diagnosis with other types of arthritides encountered in this age group, such as elderly-onset rheumatoid arthritis, spondyloarthropathies, crystal-induced arthropathies or the rare remittent seronegative symmetrical synovitis with pitting edema. Relatively typical patterns of [¹⁸F]FDG-PET/CT are well known, based on the clinical distribution of the disease (eg, scapular and pelvic girdle, interspinous bursae, sterno-costoclavicular joints, entheses), especially the hypermetabolism at the interspinous lumbar bursae that has shown the best post-test likelihood ratio in a meta-analysis. This article focuses on the differential diagnosis and on the visual and semi-quantitative tools that can be used to guide to the correct diagnosis of PMR as an add-on to the clinical picture. Further, we briefly discuss the options that can improve molecular imaging in the future for inflammatory rheumatisms in elderly.

The field of nuclear medicine has witnessed significant advancements in recent years, particularly in the area of PET imaging. One such development is the use of Fibroblast Activation Protein Inhibitors (FAPI) as a novel radiotracer. FAPI PET imaging has shown promising results in various malignancies, including sarcomas, which are a diverse group of cancers originating from mesenchymal cells. This paper aims to explore the potential of FAPI PET imaging in the diagnosis, staging, and treatment monitoring of sarcomas. Several studies have demonstrated the potential of FAPI PET in sarcomas. Furthermore, FAPI PET imaging has shown potential in assessing treatment response, with changes in FAPI uptake correlating with treatment outcomes. However, there are challenges to be addressed. The heterogeneity of sarcomas, both inter- and intra-tumoral, may affect the uniformity of Fibroblast Activation Protein (FAP) expression and thus the effectiveness of FAPI PET imaging. Additionally, the optimal timing and dosage of FAPI for PET imaging in sarcomas need further investigation. In conclusion, the introduction of FAPI PET imaging represents a significant advancement in the field of nuclear medicine and oncology. The ability to target FAP, a protein overexpressed in the majority of sarcomas, offers new possibilities for the diagnosis and treatment of these complex and diverse tumors. Its potential applications in diagnosis, staging, and theranostics are vast, and on-going research continues to explore and address its limitations. As we continue to deepen our understanding of this novel imaging technique, it is hoped that FAPI PET imaging will play an increasingly important role in the fight against cancer. However, as with any new technology, further research is needed to fully understand the potential and limitations of FAPI PET imaging in the clinical setting.

Spondylodiscitis, characterized by inflammation of the intervertebral disc and adjacent vertebral bodies, presents a diagnostic challenge due to its nonspecific clinical manifestations and variable imaging findings.

This review examines the role of PET-CT with FDG, in the evaluation of spondylodiscitis, focusing on its utility in diagnosis, assessment of disease extent, treatment response monitoring, and prognostication.

FDG PET-CT, by combining metabolic and anatomical imaging modalities, offers superior sensitivity and specificity compared to conventional imaging techniques in detecting infectious foci, distinguishing between infection and post-treatment changes, and identifying occult sources of infection. Additionally, FDG PET-CT facilitates the localization of infection, aiding in targeted biopsy and guiding surgical intervention. Moreover, quantitative PET parameters, such as standardized uptake values (SUVs), hold promise for predicting treatment response and prognosis. Despite its advantages, FDG PET-CT has limitations, including false-positive results in the setting of inflammation and limited availability in resource-constrained settings.

Collaborative efforts between radiologists, nuclear medicine specialists, infectious disease specialists, and spine surgeons are essential to optimize the role of FDG PET-CT in the multidisciplinary management of spondylodiscitis. Further research is warranted to elucidate the cost-effectiveness and clinical impact of FDG PET-CT in this challenging clinical entity.

Soft tissue sarcomas account for 6%-8% of pediatric cancers. The rhabdomyosarcoma family is the most frequent soft tissue sarcoma in this age group accounting for 3% of pediatric cancers. Rhabdomyosarcomas are high-grade tumors with a high propensity to metastasize. The risk-adapted, multimodal therapeutic approach for rhabdomyosarcomas incorporates a combination of surgery, radiotherapy, and multi-agent cytotoxic chemotherapy.

Soft tissue sarcomas other than rhabdomyosarcoma account for 3%-4% of pediatric cancers. The nonrhabdomyosarcoma soft tissue sarcomas include both low-grade and high-grade tumors. While surgery is the mainstay of therapy in most non-rhabdomyosarcoma soft tissue sarcomas, many cases require a multimodal therapeutic approach including radiotherapy and chemotherapy.

In North America, most pediatric patients with soft tissue sarcomas are treated in Children's Oncology Group clinical trials. In this article, we will primarily focus on the staging, risk stratification, imaging recommendations, and interpretations in accordance with the Children's Oncology Group trials. We will review the results and recommendations of International Soft Tissue Sarcoma Database Consortium and European trials in relevant sections where they provide complementary guidelines.

Recent developments in hybrid SPECT/CT systems and the use of cadmium-zinc-telluride (CZT) detectors have improved the diagnostic accuracy of bone scintigraphy. These advancements have paved the way for novel quantitative approaches to accurate and reproducible treatment monitoring of bone metastases. PET/CT imaging using [¹⁸F]F-FDG and [¹⁸F]F-NaF have shown promising clinical utility in bone metastases assessment and monitoring response to therapy and prediction of treatment response in a broad range of malignancies. Additionally, specific tumor-targeting tracers like [^99mTc]Tc-PSMA, [⁶⁸Ga]Ga-PSMA, or [¹¹C]C- or [¹⁸F]F-Choline revealed high diagnostic performance for early assessment and prognostication of bone metastases, particularly in prostate cancer. PET/MRI appears highly accurate imaging modality, but has associated limitations notably, limited availability, more complex logistics and high installation costs. Advances in artificial intelligence (Al) seem to improve the accuracy of imaging modalities and provide an assistant role in the evaluation of treatment response of bone metastases.

Osteoporosis is a common disease, particularly prevalent in geriatric populations, which causes significant worldwide morbidity due to increased bone fragility and fracture risk. Currently, the gold-standard modality for diagnosis and evaluation of osteoporosis progression and treatment relies on dual-energy x-ray absorptiometry (DXA), which measures bone mineral density (BMD) and calculates a score based upon standard deviation of measured BMD from the mean. However, other imaging modalities can also be used to evaluate osteoporosis. Here, we review historical as well as current research into development of new imaging modalities that can provide more nuanced or opportunistic analyses of bone quality, turnover, and density that can be helpful in triaging severity and determining treatment success in osteoporosis. We discuss the use of opportunistic computed tomography (CT) scans, as well as the use of quantitative CT to help determine fracture risk and perform more detailed bone quality analysis than would be allowed by DXA . Within magnetic resonance imaging (MRI), new developments include the use of advanced MRI techniques such as quantitative susceptibility mapping (QSM), magnetic resonance spectroscopy, and chemical shift encoding-based water-fat MRI (CSE-MRI) to enable clinicians improved assessment of nonmineralized bone compartments as well as a way to longitudinally assess bone quality without the repeated exposure to ionizing radiation. Within ultrasound, development of quantitative ultrasound shows promise particularly in future low-cost, broadly available screening tools. We focus primarily on historical and recent developments within radiotracer use as applicable to osteoporosis, particularly in the use of hybrid methods such as NaF-PET/CT, wherein patients with osteoporosis show reduced uptake of radiotracers such as NaF. Use of radiotracers may provide clinicians with even earlier detection windows for osteoporosis than would traditional biomarkers. Given the metabolic nature of this disease, current investigation into the role molecular imaging can play in the prediction of this disease as well as in replacing invasive diagnostic procedures shows particular promise.

Soft tissue sarcomas are a rare and heterogenous group of tumors that account for 2% of all cancer-related deaths. Molecular imaging with FDG PET can offer valuable metabolic information to help inform clinical management of soft tissue sarcomas that is unique and complementary to conventional diagnostic imaging techniques. FDG PET imaging often correlates with tumor grade, can help guide biopsy, and frequently detects additional sites of disease compared to conventional imaging in patients being considered for definitive or salvage therapy. Traditional size-based evaluation of treatment response is often inadequate in soft tissue sarcoma and changes in metabolic activity can add significant value to interim and end of treatment imaging for high-grade sarcomas. FDG PET can be used for detection of recurrence or malignant transformation and thus play a vital role in surveillance. This article reviews the evolving role of FDG PET in initial diagnosis, staging, treatment response assessment, and restaging. Further studies on the use of FDG PET in soft sarcoma are needed, particularly for rare histopathologic subtypes.