Inflammatory joint disorders are highly prevalent in most countries and represent a huge physical burden to the patients as well as major costs to health systems. Clinical evaluation is the basis for a correct diagnosis and appropriate treatment but in some indications, additional imaging may be necessary for a more precise assessment before and following therapy. Functional imaging using positron emission tomography combined with computerized tomography (PET/CT) offers high sensitivity for this purpose even in clinically silent disease. [18F]-FDG PET/CT is widely available and currently the mostly used technique, especially in rheumatoid arthritis and polymyalgia rheumatica and similar entities in elderly patients. However, [18F]-FDG lacks specificity and alternative tracers have been developed during the last years. They include macrophage targeting using the translocator protein (TSPO) or folate receptors as well as the more recently accessible ligands of the fibroblast-activation proteins (FAPIs). In some disorders, such as spondyloarthropathies and psoriatic arthritis, the bone-seeking agent 18F-sodium fluoride is more performant as these disorders involve mainly bone remodelling and formation rather than inflammation.

To evaluate the potential prognostic value of pretherapeutic Bone Marrow Scintigraphy (BMS) in metastatic castration-resistant prostate cancer (mCRPC) patients treated with Ra-223 dichloride (Ra-223). We analyzed 28 mCRPC patients who performed BMS and treated with Ra-223. Visual image analysis was performed and defined as follows: normal distribution (uptake in the vertebral column and bony pelvis) vs. medullary expansion (uptake at the distal half of femoral and/or humeral diaphysis or more distally). Correlation between medullary expansion status and baseline laboratory factors was performed. Survival analyses for evaluating the association between medullary expansion and other variables with overall survival (OS) were conducted using cox regression hazard model and Kaplan Meier methods. A total of 130 doses of Ra-223 were administered, with 17 (60

18F fluorodeoxyglucose ([18F]FDG) positron emission tomography/computed tomography (PET/CT) has established itself as a critical diagnostic tool in the evaluation of patients with bacteremia and fever of unknown origin (FUO), particularly following futile conventional investigations. These conditions are often challenging due to diverse underlying etiologies, including infections, inflammatory conditions and malignancies. PET/CT has the advantage of being a whole-body imaging technique with high sensitivity for detecting areas of increased metabolism often associated with infection or inflammation. In bacteremia, [18F]FDG PET/CT can help identify metastatic infections, endocarditis, or abscesses which may be clinically silent and missed on conventional imaging. In FUO, it helps to identify underlying etiologies, directing treatment and management strategies. This review aims to describe the role of PET/CT imaging in these diverse clinical scenarios. Perspectives in the field, including novel equipment and tracers, will be briefly discussed.

A joint task force of subject-matter experts from the European Association of Nuclear Medicine (EANM) and the Society of Nuclear Medicine and Molecular Imaging (SNMMI) recently released a revised and updated guideline/procedure standard for indications and protocols for hybrid [18F]FDG imaging in

INTRODUCTION:Nasal irrigations are a longstanding modality of treatment. Mechanical nasal lavage and irrigation of the nasal cavities and paranasal sinuses are frequently conflated under the principle of nasal irrigations even if the objectives are different. AREAS COVERED:The aims and principles of these two different modalities are described in the first part of the paper. In the second part, the literature is summarized based on the data related to the clinical efficacy of the nasal irrigation and on the results of the studies assessing the physical efficacy of the delivery. EXPERT OPINION:Although abundant, the literature does not provide strong enough evidence about the optimal nasal irrigation modality. There is a genuine need for a clear definition of terms and evidence-based recommendations on the techniques that should be proposed to patients according to specific clinical objectives. The authors proposed a new terminology to distinguish between nasal clearance irrigation and nasal drug irrigation.

The European Union Radiation, Education, Staffing & Training (EU-REST) study was a European Commission-funded, 24-month project that analysed workforce availability, education and training needs to ensure quality and safety aspects of medical applications involving ionising radiation in the EU and developed staffing and education/training guidelines for key professional groups involved in ensuring radiation safety and quality of medical radiation applications in the EU Member States. This article outlines the origin, development, goals and overall structure of the project. CRITICAL RELEVANCE STATEMENT: This article provides a concise overview of the EU-REST project, which analysed the workforce availability of health professionals involved in the use of ionising radiation for diagnostic and therapeutic procedures and the corresponding education and training in radiation protection. KEY POINTS: The aims, professional groups, components, and findings of The European Union Radiation, Education, Staffing & Training (EU-REST) study are described. The limited amount of data and literature on staffing recommendations constituted an important finding of the project. One of the study's recommendations is for each EU Member State to maintain a central registry of professionals involved in ionising radiation as well as on related equipment.

Background Large field of view CZT SPECT cameras with a ring geometry are available for some years now. Thanks to their good sensitivity and high temporal resolution, general dynamic SPECT imaging may be performed more easily, without resorting to dedicated systems. To evaluate the dynamic SPECT imaging by such cameras, we have performed an in vivo pilot study to analyze the kidney function of a pig and compare the results to standard dynamic planar imaging by a conventional gamma camera.Methods A 7-week-old (12 kg) female Landrace pig was injected with [99mTc]Tc-MAG3 and a 30 min dynamic SPECT acquisition of the kidneys was performed on a CZT ring camera. A fast SPECT/CT was acquired with the same camera immediately after the dynamic SPECT, without moving the pig, and used for attenuation correction and drawing regions of interest. The next day the same pig underwent a dynamic planar imaging of the kidneys by a conventional 2-head gamma camera. The dynamic SPECT acquisition was reconstructed using a MLEM algorithm with up to 20 iterations, with and without attenuation correction. Time-activity curves of the total counts of each kidney were extracted from 2D and 3D dynamic images. An adapted 2-compartment model was derived to fit the data points and extract physiological parameters. Comparison of these parameters was performed between the different reconstructions and acquisitions.Results Time-activity curves were nicely fitted with the 2-compartment model taking into account the anesthesia and bladder filling. Kidney physiological parameters were found in agreement with literature values. Good agreement of these parameters was obtained for the right kidney between dynamic SPECT and planar imaging. Regional analysis of the kidneys can be performed in the case of the dynamic SPECT imaging and provided good agreement with the whole kidney results.Conclusions Dynamic SPECT imaging is feasible with CZT swiveling-detector ring cameras and provides results in agreement with dynamic planar imaging by conventional gamma cameras. Regional analysis of organs uptake and clearance becomes possible. Further studies are required regarding the optimization of acquisition and reconstruction parameters to improve image quality and enable absolute quantification.

Hybrid [18F]FDG PET imaging is currently the method of choice for a wide variety of infectious and inflammatory disorders and was recently adopted in several clinical guidelines. A large amount of evidence-based articles, guidelines and appropriate use criteria have been published since the first version of this guideline in 2013. To provide updated evidence-based information to assist physicians in recommending, performing and interpreting hybrid [18F]FDG PET examinations for infectious and inflammatory disorders in the adult population. A systematic literature search of evidence-based articles using whole-body [18F]FDG hybrid imaging on the indications covered within this guideline was performed. All systematic reviews and meta-analyses published within the last 10 years until January 2023 were identified in PubMed/Medline or Cochrane. For each indication covered in this manuscript, diagnostic performance was provided based on meta-analyses or systematic reviews. If not available, results from prospective or retrospective studies were considered based on predefined selection criteria. Hybrid [18F]FDG PET is extremely useful in the work-up and management of adults with infectious and inflammatory diseases, as supported by extensive and rapidly growing evidence-based literature and adoption in clinical guidelines. Practical recommendations are provided describing evidence-based indications as well as interpretation criteria and pitfalls. Monitoring treatment response is the most challenging but insufficiently studied potential application in infection and inflammation imaging.

Objective: Staphylococcus aureus bacteremia (SAB) is a leading cause of community and hospital-acquired bacteremia with significant morbidity and mortality. Effective management depends on accurate diagnosis, source control and assessment of metastatic infections. [F-18] FDG PET/CT has been shown to reduce mortality in high-risk SAB patients. This study aims to evaluate the impact of [F-18] FDG PET/CT on outcomes in patients with SAB. Methods: Single-center, retrospective, real-life setting study including all consecutive SAB cases from 2017 to 2019. Medical records were analyzed to collect information. Results: Out of the 315 included patients, 132 underwent [F-18] FDG PET/CT. In those patients, a clear focus of infection was more frequently identified, leading to better adapted treatments and extended hospital stays. Overall mortality rates at 30 days, 90 days and one year were 25.1 %, 36.8 % and 44.8 % respectively. Mortality was significantly lower in the [F-18] FDG PET/CT group (p < 0.0001) and persisted (p < 0.05) after adjusting for imbalances between groups regarding oncologic patients and deaths within 7 days. The difference in mortality remained significant irrespective of prolonged bacteremia but was not significant with regard to hospital-acquired SAB. Supplementary analysis using the Cox proportional hazards model confirmed that [F-18] FDG PET/CT was significantly associated with reduced mortality (p < 0.05). Conclusion: In this real-life cohort, patients with SAB having undergone [F-18] FDG PET/CT experienced lower mortality rates, highlighting the additional value of [F-18] FDG PET/CT in SAB management. Further research is needed to identify the subpopulations that would benefit most from the integration of [F-18] FDG PET/CT in their work-up.

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 recent development of radionuclide therapy and radioligand therapy has raised a call for achieving the highest quality standards, for either radiopharmacy or radiation protection. Novel radionuclides are now being used, either under the form of in-house production radiopharmaceuticals or available from companies. Over the last 20 years, they include radiolabeled microspheres for selective internal radiotherapy (SIRT), the introduction of the first commercially available alpha emitter radiopharmaceutical, 223Ra, and the radiosynoviorthesis which is highly variable across Europe. More important is the development of radioligand therapy, often called theranostics. In this concept, a diagnostic radiopharmaceutical can determine the chance of success of a therapeutic one. Typically, diagnostic radiopharmaceuticals for positron emission tomography, are labeled with 18F or 68Ga, such as the PSMA ligands or somatostatin analogs, and the therapeutic radiopharmaceutical is labeled with 177Lu. This has revolutionized the world of Nuclear Medicine, but also all concepts that shall be applied to properly apply quality assurance and radiation protection in the field. This article will follow the example of 131I as the main used radionuclide for therapy during the last 80 years. Proposals can be general, and in parallel expert's articles will give specific guidance on issues with particular radionuclides, i.e., alpha emitters and 177Lu. This article will also give insight in the radiation protection issues related to the use of microspheres radiolabeled with either 90Y or 166Ho.

Abstract Background The administration technique for inhaled drug delivery during invasive ventilation remains debated. This study aimed to compare in vivo and in vitro the deposition of a radiolabeled aerosol generated through four configurations during invasive ventilation, including setups optimizing drug delivery. Methods Thirty-one intubated postoperative neurosurgery patients with healthy lungs were randomly assigned to four configurations of aerosol delivery using a vibrating-mesh nebulizer and specific ventilator settings: (1) a specific circuit for aerosol therapy (SCAT) with the nebulizer placed at 30 cm of the wye, (2) a heated-humidified circuit switched off 30 min before the nebulization or (3) left on with the nebulizer at the inlet of the heated-humidifier, (4) a conventional circuit with the nebulizer placed between the heat and moisture exchanger filter and the endotracheal tube. Aerosol deposition was analyzed using planar scintigraphy. Results A two to three times greater lung delivery was measured in the SCAT group, reaching 19.7% (14.0–24.5) of the nominal dose in comparison to the three other groups (p < 0.01). Around 50 to 60% of lung doses reached the outer region of both lungs in all groups. Drug doses in inner and outer lung regions were significantly increased in the SCAT group (p < 0.01), except for the outer right lung region in the fourth group due to preferential drug trickling from the endotracheal tube and the trachea to the right bronchi. Similar lung delivery was observed whether the heated humidifier was switched off or left on. Inhaled doses measured in vitro correlated with lung doses (R = 0.768, p < 0.001). Conclusion Optimizing the administration technique enables a significant increase in inhaled drug delivery to the lungs, including peripheral airways. Before adapting mechanical ventilation, studies are required to continue this optimization and to assess its impact on drug delivery and patient outcome in comparison to more usual settings.

The nasal administration route emerged as an interesting route in systemic and brain drug delivery, and different modalities of nasal delivery are available. The nasal irrigation is one of them, but there is a lack of studies investigating the distribution of a large-volume irrigation. The main aim of this study was to assess the deposition of radiolabeled saline in the nasal cavities and paranasal sinuses following nasal irrigation by imaging. Five healthy males volunteered to perform large-volume low-pressure nasal irrigation, with a douching device containing 50 mL of radiolabeled isotonic saline. Participants underwent a scintigraphy immediately after. Both the nasal cavities and maxillary sinuses were systematically reached by the solution during nasal irrigation. The sinuses set in a lower position during nasal irrigation showed a tendency to be more irrigated than the sinuses set in a higher position (7.67

[18F]FDG PET/CT is used in the workup of indeterminate soft tissue tumors (STTs) but lacks accuracy in the detection of malignant STTs. The aim of this study is to evaluate whether dual-time point [18F]FDG PET/CT imaging (DTPI) can be useful in this indication. In this prospective study, [18F]FDG PET/CT imaging was performed 1 h (t1) and 3 h (t2) after injection. Tumor uptake (SUVmax) was calculated at each time point to define a retention index (RI) corresponding to the variation between t1 and t2 (%). Sixty-eight patients were included, representing 20 benign and 48 malignant tumors (including 40 sarcomas). The RI was significantly higher in malignant STTs than in benign STTs (median: +21.8% vs. −2%, p < 0.001). An RI of >14.3% predicted STT malignancy with a specificity (Sp) of 90% and a sensitivity (Se) of 69%. An SUVmaxt1 of >4.5 was less accurate with an Sp of 80% and an Se of 60%. In a subgroup of tumors with at least mild [18F]FDG uptake (SUVmax ≥ 3; n = 46), the RI significantly outperformed the diagnostic accuracy of SUVmax (AUC: 0.88 vs. 0.68, p = 0.01). DTPI identifies malignant STT tumors with high specificity and outperforms the diagnostic accuracy of standard PET/CT.

Bone imaging has been intimately associated with the diagnosis and staging of multiple myeloma (MM) for more than 5 decades, as the presence of bone lesions indicates advanced disease and dictates treatment initiation. The methods used have been evolving, and the historical radiographic skeletal survey has been replaced by whole body CT, whole body MRI (WB-MRI) and [18F]FDG-PET/CT for the detection of bone marrow lesions and less frequent extramedullary plasmacytomas.Beyond diagnosis, imaging methods are expected to provide the clinician with evaluation of the response to treatment. Imaging techniques are consistently challenged as treatments become more and more efficient, inducing profound response, with more subtle residual disease. WB-MRI and FDG-PET/CT are the methods of choice to address these challenges, being able to assess disease progression or response and to detect "minimal" residual disease, providing key prognostic information and guiding necessary change of treatment.This paper provides an up-to-date overview of the WB-MRI and PET/CT techniques, their observations in responsive and progressive disease and their role and limitations in capturing minimal residual disease. It reviews trials assessing these techniques for response evaluation, points out the limited comparisons between both methods and highlights their complementarity with most recent molecular methods (next-generation flow cytometry, next-generation sequencing) to detect minimal residual disease. It underlines the important role of PET/MRI technology as a research tool to compare the effectiveness and complementarity of both methods to address the key clinical questions.

In this issue of The Journal of Nuclear Medicine, Thornton et al. present F-FDG PET/CT data obtained on coronavirus disease 2019 (COVID-19) patients at several disease stages (1). The study includes predominantly oncology patients in whom the diagnosis of severe acute respiratory syndrome coronavirus 2 (SARS-Cov-2) infection was not known before the PET/CT procedure (n5 32), as well as 18 patients with known infection and persistent shortness of breath 28 d after the onset of disease and who were previously admitted to the hospital for oxygen therapy. The latter group was categorized as potential post–COVID-19 lung disease (PCLD) (2). In this PCLD group, half the patients had ongoing corticosteroid treatment. Although retrospective, this study triggers an interesting discussion on the potential role of F-FDG PET/CT in patients with late COVID-19 infection. After the initial outbreak of SARS-CoV-2 in December 2019, 3–4 waves of the pandemic have been observed worldwide. As of September 26, 2021, and according to the data of the Johns Hopkins University (https://coronavirus.jhu.edu), more than 230 million people were diagnosed worldwide, with a death toll close to 5 million, making it the largest and deadliest pandemic since the 1918 flu. Importantly, the disease presentation at the early phases ranged from asymptomatic contamination to mild symptoms over overt symptoms requiring hospitalization with oxygen therapy and, at the extreme, assisted ventilation or extracorporeal membrane oxygenation. Shah et al. defined 3 phases of the disease: acute COVID-19 infection with signs and symptoms up to 4 wk, ongoing symptomatic COVID-19 between 4 and 12 wk, and PCLD syndrome beyond 12 wk, when persisting symptoms cannot be attributed to alternative diagnoses (3). The term long COVID commonly refers to both ongoing symptomatic COVID-19 and PCLD as defined above. Several studies describe persistent symptoms in patients after acute COVID-19, with one third or more experiencing more than one symptom, including fatigue, abnormal breathing, chest or throat pain, headache, and cognitive symptoms up to 3–6 mo after diagnosis. Such persistent symptoms are more frequently reported after COVID-19 than after influenza infection. However, this perspective will focus on subacute and chronic lung disease, referred to as PCLD. Five percent of COVID-19 survivors evolve to chronic respiratory failure, manifested by breathlessness, cough, or even oxygen needs (4). From the very beginning of the outbreak, multiple casuistic reports on F-FDG PET/CT were published, without emphasis on the time course, since the initial observations focused either on the most acute phase in severely ill patients or on serendipitous findings in asymptomatic oncology patients. Several studies indicated a 2to 4-fold increased incidence of interstitial pneumonia detected on F-FDG PET/CT in the latter group during the early phase of the pandemic (5). Other authors identified a relationship between the structural changes as assessed using the COVID-19 Reporting and Data System and metabolic changes (6). Albeit informative, such reports did not take into account the temporal kinetics of the disease. It has become clear that F-FDG PET/CT has a limited role, if any, in establishing the diagnosis of active COVID-19 infection. From a logistic viewpoint, organizing a PET/CT scan in a nuclear medicine department had more drawbacks than advantages, as compared with dedicated CT-scan suites, with a rapid turnover even with the implementation of all necessary hygiene measures. Several reports indicate that F-FDG PET/CT results in the early phase of the disease were similar to those observed in the literature on pneumonia due to other aggressive viruses. In this retrospective observational study, Thornton et al. were able to distinguish several temporal patterns in a limited number of subjects during the first 2 peaks of COVID-19. Using F-FDG PET/CT, they not only studied the functional and morphologic pattern at different disease stages but also demonstrated the time relationship between these changes. In asymptomatic patients, without any history or suggestion of a COVID-19 diagnosis, the authors identified 2 distinct groups: one group of acute patients in the early stage (n5 8) with typical ground-glass changes on CT and relatively low F-FDG uptake (median SUVmax, 1.6, and median target-to-background ratio [TBRlung], 6.4, where the background refers to the lowest lung uptake) and a second group of acute patients in the late stage, with a more extensive consolidation pattern on CT and a significantly higher SUVmax (median, 4.0) and TBRlung (median, 13.7) (P5 0.001). SUVmax was similar in a small series of convalescing patients reported by Bai et al., but these were patients recovering from severe infection (7). Temporal data in the study of Received Oct. 1, 2021; revision accepted Oct. 12, 2021. For correspondence or reprints, contact François Jamar (francois.jamar@ uclouvain.be). Published online Oct. 21, 2021. COPYRIGHT 2022 by the Society of Nuclear Medicine andMolecular Imaging. DOI: 10.2967/jnumed.121.263166

Current hole matching pixel detector (HMPD)collimators for SPECT imaging exist in two configurations: one hole per pixel(1HMPD) or four holes per pixel (4HMPD). The aim of this study was to assessthe performance of a dual-layer collimator made by stacking up these twocollimator types (1H/4HMDP) for low and medium-energy gamma emitters.Analytical equations describing 1H/4HMDP collimator geometrical efficiency andfull width at half maximum (FWHM) were derived. In addition, a fast dedicatedgamma ray-tracing Monte Carlo (MC) code was developed to assess thecollimator’s point spread function (PSF) and to simulate planar and SPECTacquisitions. A relative agreement between analytical equations and MCsimulations better than 3% was observed for the efficiency and better than 1% forthe FWHM. The length of the two layers was optimized to get the best spatialresolution while keeping the geometrical efficiency equal to that of the45mm-length 1HMPD collimator. An optimized combination of the 1H/4HMPDconfiguration with respective hole lengths of 20mm and 12.95mm has beenderived. For source-collimator distances above 5 cm and equal collimatorgeometrical efficiency, the spatial resolution of this optimal 1H/4HMDPcollimator supersedes that of the 45mm-length 1HMPD collimator, and that of the19.1mm-length 4HMPD collimator. This improvement was observed in simulations ofbar phantoms planar images and of hot rods phantom SPECT. Remarkably, thespatial resolution was preserved along the depth of the Jaszczak phantomslices. The 1H/4HMDP collimator is a promising solution for CZT SPECT imagingof low- and medium-energy emitters.