Combining Nuclear Medicine With Other Modalities: Future Prospect for Multimodality Imaging.

This meeting report summarizes a consultants meeting that was held at International Atomic Energy Agency Headquarters, Vienna, in July 2022 to provide an update on the development of multimodality imaging by combining nuclear medicine imaging agents with other nonradioactive molecular probes and/or biomedical imaging techniques.

A CAIX Dual-Targeting Small-Molecule Probe for Noninvasive Imaging of ccRCC.

Carbonic anhydrase IX (CAIX), a zinc metal transmembrane protein, is highly expressed in 95% of clear cell renal cell carcinomas (ccRCCs). A positron emission tomography (PET) probe designed to target CAIX in nuclear medicine imaging technology can achieve precise positioning, is noninvasive, and can be used to monitor CAIX expression in lesions in real time. In this study, we constructed a novel acetazolamide dual-targeted small-molecule probe [68Ga]Ga-LF-4, which targets CAIX by binding to a specific amino acid sequence. After attenuation correction, the radiolabeling yield reached 66.95 ± 0.57% (n = 5) after 15 min of reaction and the radiochemical purity reached 99% (n = 5). [68Ga]Ga-LF-4 has good in vitro and in vivo stability, and in vivo safety and high affinity for CAIX, with a Kd value of 6.62 nM. Moreover, [68Ga]Ga-LF-4 could be quickly cleared from the blood in vivo. The biodistribution study revealed that the [68Ga]Ga-LF-4 signal was concentrated in the heart, lung, and kidney after administration, which was the same as that observed in the micro-PET/CT study. In a ccRCC patient-derived xenograft (PDX) model, the signal significantly accumulated in the tumor after administration, where it was retained for up to 4 h. After competitive blockade with LF-4, uptake at the tumor site was significantly reduced. The SUVmax of the probe [68Ga]Ga-LF-4 at the ccRCC tumor site was three times greater than that in the PC3 group with low CAIX expression at 30 min (ccRCC vs PC3:1.86 ± 0.03 vs 0.62 ± 0.01, t = 48.2, P < 0.0001). These results indicate that [68Ga]Ga-LF-4 is a novel small-molecule probe that targets CAIX and can be used to image localized and metastatic ccRCC lesions.

Improvements and future perspective in diagnostic tools for neuroendocrine neoplasms.

INTRODUCTION: Neuroendocrine neoplasms (NENs) represent a complex group of tumors arising from neuroendocrine cells, characterized by heterogeneous behavior and challenging diagnostics. Despite advancements in medical technology, NENs present a major challenge in early detection, often leading to delayed diagnosis and variable outcomes. This review aims to provide an in-depth analysis of current diagnostic methods as well as the evolving and future directions of diagnostic strategies for NENs. AREA COVERED: The review extensively covers the evolution of diagnostic tools for NENs, from traditional imaging and biochemical tests to advanced genomic profiling and next-generation sequencing. The emerging role of technologies such as artificial intelligence, machine learning, and liquid biopsies could improve diagnostic precision, as could the integration of imaging modalities such as positron emission tomography (PET)/magnetic resonance imaging (MRI) hybrids and innovative radiotracers. EXPERT OPINION: Despite progress, there is still a significant gap in the early diagnosis of NENs. Bridging this diagnostic gap and integrating advanced technologies and precision medicine are crucial to improving patient outcomes. However, challenges such as low clinical awareness, limited possibility of noninvasive diagnostic tools and funding limitations for rare diseases like NENs are acknowledged.

Object and person tracking systems to enable extremity dosimetry in nuclear medicine using computational methods.

Nuclear medicine (NM) professionals are potentially exposed to high doses of ionising radiation, particularly in the skin of the hands. Ring dosimeters are used by the workers to ensure extremity doses are kept below the legal limits. However, ring dosimeters are often susceptible to large uncertainties, so it is difficult to ensure a correct measurement using the traditional occupational monitoring methods. An alternative solution is to calculate the absorbed dose by using Monte Carlo simulations. This method could reduce the uncertainty in dose calculation if the exact positions of the worker and the radiation source are represented in these simulations. In this study we present a set of computer vision and artificial intelligence algorithms that allow us to track the exact position of unshielded syringes and the hands of NM workers. We showcase a possible hardware configuration to acquire the necessary input data for the algorithms. And finally, we assess the tracking confidence of our software. The tracking accuracy achieved for the syringe detection was 57% and for the hand detection 98%.

Intra-operative lymphatic mapping and sentinel node biopsy in laryngeal carcinoma using radiotracer injection.

OBJECTIVE: The purpose of this study was to determine the value of sentinel lymph node biopsy (SLNB) in the laryngeal SCC, using intra-operative peri-tumoral injection of Tc-99m-phytate. METHODS: Patients with biopsy-proven squamous cell carcinoma of the larynx were included. On the day of surgery, after anesthesia induction, suspension laryngoscopy was performed to inject 74 MBq/0.4 ml Tc-99m-phytate in four aliquots into the sub-mucosal peri-tumoral location. After a 10-min wait, a portable gamma probe was used to locate sentinel nodes. Subsequently, all patients underwent laryngectomy and neck dissection. Both sentinel nodes and non-sentinel nodes were examined using hematoxylin and eosin (H&E) staining. RESULTS: Twenty-six patients with a diagnosis of laryngeal carcinoma were included in the study. The SLN detection rate was 65.4%, with a 100% detection rate in the supraglottic region and a 52.6% detection rate for glottis/transglottic patients. Permanent pathology results showed lymph node involvement in four patients, but only one patient had a negative result in the SLNB, resulting in an overall false negative rate of 25%. The sensitivity of the SLN technique was 75% overall, 100% in the supraglottic region, and 67% in the glottis/transglottic region. CONCLUSION: The accuracy and feasibility of SLNB may be related to the location of the tumors in the larynx. For supraglottic tumors, the technique seems to be feasible with a low false negative rate. For glottis/transglottic tumors, both the detection rate and false negative rate seem to be suboptimal. Further studies are needed to validate our results.

Determinants of successful ictal SPECT injection in phase 1 epilepsy presurgical evaluation: Findings from the pediatric epilepsy research consortium surgery database project.

OBJECTIVES: The main goal of presurgical evaluation in drug-resistant focal epilepsy is to identify a seizure onset zone (SOZ). Of the noninvasive, yet resource-intensive tests available, ictal single-photon emission computed tomography (SPECT) aids SOZ localization by measuring focal increases in blood flow within the SOZ via intravenous peri-ictal radionuclide administration. Recent studies indicate that geographic and center-specific factors impact utilization of these diagnostic procedures. Our study analyzed successful ictal SPECT acquisition (defined as peri-ictal injection during inpatient admission) using surgery-related data from the Pediatric Epilepsy Research Consortium (PERC) surgery database. We hypothesized that a high seizure burden, longer duration of video EEG monitoring (VEEG), and more center-specific hours of SPECT availability would increase the likelihood of successful ictal SPECT. METHODS: We identified study participants (≤18 years of age) who underwent SPECT as part of their phase 1 VEEG from January 2018 to June 2022. We assessed association between ictal SPECT outcomes (success vs. failure) and variables including patient demographics, epilepsy history, and center-specific SPECT practices. RESULTS: Phase 1 VEEG monitoring with ictal SPECT injection was planned in 297 participants and successful in 255 participants (85.86%). On multivariable analysis, the likelihood of a successful SPECT injection was higher in patients of non-Hispanic ethnicity (p = 0.040), shorter duration VEEG (p = 0.004), and higher hours of available SPECT services (p < 0.001). Higher seizure frequency (p = 0.033) was significant only in bivariate analysis. Patients treated at centers with more operational hours were more likely to experience pre-admission protocols prior to VEEG (p = 0.002). SIGNIFICANCE: There is inter-center variability in protocols and SPECT acquisition capabilities. Shorter duration of EEG monitoring, non-Hispanic ethnicity (when on private insurance), extended operational hours of nuclear medicine as noted on multivariate analysis and higher seizure frequency in bivariate analysis are strongly associated with successful ictal SPECT injection. PLAIN LANGUAGE SUMMARY: In pediatric patients with drug-resistant epilepsy, single-photon emission computed tomography (SPECT) scans can be helpful in localizing seizure onset zone. However, due to many logistical challenges described below, which include not only the half-life of the technetium isotope used to inject intravenously during a seizure (called the ictal SPECT scan) but also available nuclear scanner time in addition to the unpredictability of seizures, obtaining an ictal SPECT during a planned elective inpatient hospital stay is not guaranteed. Thus, as healthcare costs increase, planning a prolonged hospital stay during which an ictal SPECT scan is not feasible is not optimal. We leveraged our prospective surgery database to look at center-specific factors and patient-specific factors associated with an ictal SPECT injection in the first, pediatric-focussed, large-scale, multicenter, prospective, SPECT feasibility study. We found that longer availability of the scanner is the most important center-specific factor in assuring ictal SPECT injection. Although seizure frequency is an important patient-specific factor on bivariate analysis, this factor lost statistical significance when other factors like patient insurance status and video EEG duration were also considered in our multivariable logistical model.

A simulated clinic to build interprofessional and authentic learning opportunities for shaping future practice in medical radiation professionals.

BACKGROUND: Simulation based learning provides an opportunity to increase student readiness prior to clinical placement. Cross disciplinary learning facilitates interprofessional competency building and improved student appreciation of other health professions, which adds another learning dimension to simulated scenarios. This paper outlines the approach to facilitating an interdisciplinary simulated clinic, where experiences were mapped to common professional capabilities. METHODS: After mapping skill sets and professional capabilities common to both Nuclear Medicine and Radiation Therapy, a mock clinic was planned to address common objectives. The aims of the activity were to prepare students for upcoming clinical placement and to build knowledge and skills in the interprofessional environment. All students were allocated roles of both the health care professional and the patient and introduced to the concept of interprofessional learning in a pre-brief session. During the simulated clinic phase students experienced the other modality through the patient perspective as well as practicing the clinician role within their own modality. Following the simulation students came together for a de-brief session. The activity was evaluated using both online polling and pre and post paper-based surveys. RESULTS: A total of 28 students participated in the simulation: 17 in radiation therapy and 11 in nuclear medicine. All participants agreed that the mock clinic was valuable preparation for clinical placement. Twenty-four completed pre and post surveys, revealed a collective improvement in several measures of interprofessional understanding and application. Free text polled responses in the de-brief session highlighted value for practicing communication, realistic physical resemblance to the real-life scenarios and time pressures. CONCLUSION: When two disciplines were combined in the simulated clinic, students learnt about each other's profession together. Evaluation showed positive improvements in both clinical readiness and interprofessional learning. Simulated tasks in healthcare education bought many benefits in preparing students for the workplace and in this example, enabled common objectives of interprofessional practice to be met.

Efficacy of a Novel Respiratory Motion Reduction Block in Reducing Motion Artifact on Myocardial Perfusion Single-Photon Emission Computed Tomography.

PURPOSE: Motion artifacts caused by heart motion during myocardial perfusion single-photon emission computed tomography (SPECT) can compromise image quality and diagnostic accuracy. This study aimed to evaluate the efficacy of the novel respiratory motion reduction block (RRB) device in reducing motion artifacts by compressing the hypochondrium and improving SPECT image quality. METHODS: In total, 91 patients who underwent myocardial perfusion SPECT with 99mTc-sestamibi were retrospectively analyzed. Patients (n = 28) who underwent SPECT without the RRB were included in the control group, and those (n = 63) who underwent SPECT with the RRB were in the RRB group. The distance of heart motion during dynamic acquisition was measured, and projection data were assessed for patient motion and motion artifacts. Patient motion was classified into various levels, and motion artifacts on SPECT images were visually examined. RESULTS: The distances of heart motion without and with the RRB were 15.4 ± 5.3 and 7.5 ± 2.3, respectively. Compared with the control group, the RRB group had a lower frequency of heart motion based on the projection data, particularly in terms of creep and shift motion. The RRB group had a significantly lower incidence of motion artifacts on SPECT images than the control group. CONCLUSIONS: The RRB substantially reduced specific types of motion, such as shift and creep, and had a low influence on bounce motion. However, it could effectively suppress respiratory-induced heart motion and reduce motion artifacts on myocardial perfusion SPECT, thereby emphasizing its potential for improving image quality.

Experiences of Nuclear Medicine Technologists Working in PET/CT Facilities in Gauteng Province, South Africa.

The introduction of PET/CT requires staff training, redesign of patient workflow, new skills, problem-solving abilities, and adjustments to radiation protection protocols. When PET/CT was introduced in the U.K., nuclear medicine technologists (NMTs) encountered challenges in defining their roles and unfamiliarity with the new technology and the new working procedures. Since the introduction of PET/CT in South Africa, the experiences of NMTs with this hybrid imaging device have not yet been described. Therefore, the aim of this research study was to explore and describe the experiences of NMTs working in PET/CT facilities in Gauteng Province, South Africa. Methods: This study had a qualitative, exploratory, descriptive design and used a phenomenologic research approach. Semistructured interviews were conducted to collect data until data saturation was reached. A software program was used to manage the codes, categories, and themes. Nine NMTs participated in the study: 5 from public hospitals and 4 from private hospitals. Their age range of 27-58 y provided the ideal heterogeneity for sharing experiences in working in PET/CT facilities. Results: Two overarching themes emerged from the categories: the perspectives of NMTs working in PET/CT facilities and the PET/CT challenges encountered by NMTs. The results suggest that NMTs experience joy and fulfilment from working in PET/CT facilities and regard PET/CT as the future of nuclear medicine. However, NMTs also experience a gap in PET/CT training and are concerned about the high radiation exposure associated with PET/CT imaging and about the lack of psychologic support. Conclusion: Although the NMTs enjoy working in PET/CT, they desire additional clinical training and psychologic support. Since radiation exposure in PET/CT is higher than in general nuclear medicine, radiation monitoring is imperative to minimize exposure to NMTs and patients.

Assessment of Area Radiation Dose for the National Cyclotron and PET Centre at Chulabhorn Hospital in Thailand.

The National Cyclotron and PET Centre at Chulabhorn Hospital offers nuclear medicine diagnostic services using state-of-the-art digital PET/CT and PET/MRI machines as well as other related devices. Additionally, the center plays a vital role by having a cyclotron to produce radiopharmaceuticals, which are used both in-house and in other hospitals throughout the country. Despite the center's strict adherence to international standards regarding the use of radioactive substances in patients, there remains a potential risk of radiation exposure for operators, workers, and the public due to radioactive contamination and emissions from unsealed sources. Hence, it is imperative to assess and continuously monitor radiation levels in the work area to ensure the utmost level of safety for personnel. Methods: This study used optically stimulated luminescence dosimeters to measure radiation levels in 17 areas, consisting of 9 controlled and 8 supervised areas. Over a 3-mo period, the average monthly radiation dose was recorded for each location. Results: The PET/CT room registered the highest radiation dose within the controlled area, with a monthly average of 1.81 ± 0.29 mSv, equivalent to an annual dose of 21.72 mSv. This higher dose can be attributed to the significant number of patients served in this room. In supervised areas, the nursing counter located between the examination room and the patient waiting area exhibited the highest radiation exposure. The average monthly dose measured at this location was 0.085 ± 0.019 mSv, resulting in an annual dose of 1.015 mSv. Conclusion: The evaluation of radiation dose in controlled and supervised areas indicated that the overall radiation level remains within the prescribed limits. However, the slight excess that was observed at the nursing counter indicates the need for improvement to ensure compliance with the as-low-as-reasonably-achievable principle. Continuous monitoring of radiation levels should be conducted annually to maintain safety standards and minimize the risk that workers and the general public will be exposed to radioactivity.

Simulator Education Initiatives for On-Campus Practical Training in Nuclear Medicine Technology.

Because nuclear medicine diagnostic equipment has not been installed at our educational institution, we had not been able to incorporate nuclear medicine techniques into on-campus training until now. Methods: We have introduced a diagnostic image processing simulator to replace nuclear medicine diagnostic equipment. The simulator was used to conduct on-campus practical training on nuclear medicine technology. We also conducted a questionnaire survey of students regarding their experience with on-campus practical training using the simulators. Results: The survey results revealed that the on-campus practical training using simulators deepened students' understanding of the content they had encountered in classroom lectures. Conclusion: We successfully implemented on-campus practical training in nuclear medicine technology using a diagnostic image-processing simulator. According to the results of our questionnaire, it is possible to provide on-campus practical training to students using simulators that enhance understanding of nuclear medicine technology.

Erdheim-Chester disease and nuclear medicine imaging. A case report and brief review.

Erdheim-Chester disease (ECD) is a rare clonal myeloid neoplasm typically affecting adults over 50 years old, with bone lesions in almost all patients. The prognosis is poor in most cases if left untreated. Clinical manifestations are not specific, which hinders early diagnosis. The disease has distinct radiological features. However, three-phase bone scintigraphy exhibits the most typical pattern of all imaging modalities, which is the prominent strikingly symmetrical radiotracer uptake in the distal ends of the femurs and proximal and distal ends of the tibiae, sparing the epiphyses. We report a case of a 54-year-old female patient, presenting with atypical persistent knee joint pain. After an MRI scan, she underwent a three-phase bone scan, revealing the characteristic pattern, thus indicating a possible ECD diagnosis, which was eventually confirmed in biopsy material. Novel aspects of the pathophysiology and treatment of the disease, as well as a differential diagnosis from the perspective of an MSK radiologist and nuclear medicine physician, are also discussed.

PSMA-targeted radiotheranostics in modern nuclear medicine: then, now, and what of the future?

In 1853, the perception of prostate cancer (PCa) as a rare ailment prevailed, was described by the eminent Londoner surgeon John Adams. Rapidly forward to 2018, the landscape dramatically altered. Currently, men face a one-in-nine lifetime risk of PCa, accentuated by improved diagnostic methods and an ageing population. With more than three million men in the United States alone grappling with this disease, the overall risk of succumbing to stands at one in 39. The intricate clinical and biological diversity of PCa poses serious challenges in terms of imaging, ongoing monitoring, and disease management. In the field of theranostics, diagnostic and therapeutic approaches that harmoniously merge targeted imaging with treatments are integrated. A pivotal player in this arena is radiotheranostics, employing radionuclides for both imaging and therapy, with prostate-specific membrane antigen (PSMA) at the forefront. Clinical milestones have been reached, including FDA- and/or EMA-approved PSMA-targeted radiodiagnostic agents, such as [18F]DCFPyL (PYLARIFY®, Lantheus Holdings), [18F]rhPSMA-7.3 (POSLUMA®, Blue Earth Diagnostics) and [68Ga]Ga-PSMA-11 (Locametz®, Novartis/ ILLUCCIX®, Telix Pharmaceuticals), as well as PSMA-targeted radiotherapeutic agents, such as [177Lu]Lu-PSMA-617 (Pluvicto®, Novartis). Concurrently, ligand-drug and immune therapies designed to target PSMA are being advanced through rigorous preclinical research and clinical trials. This review delves into the annals of PSMA-targeted radiotheranostics, exploring its historical evolution as a signature molecule in PCa management. We scrutinise its clinical ramifications, acknowledge its limitations, and peer into the avenues that need further exploration. In the crucible of scientific inquiry, we aim to illuminate the path toward a future where the enigma of PCa is deciphered and where its menace is met with precise and effective countermeasures. In the following sections, we discuss the intriguing terrain of PCa radiotheranostics through the lens of PSMA, with the fervent hope of advancing our understanding and enhancing clinical practice.

Pharmacokinetic evaluation of paclitaxel, albumin-binding paclitaxel, and liposomal-encapsulated albumin-binding paclitaxel upon gastric subserosal administration.

Introduction: Systemic chemotherapy is typically administered following radical gastrectomy for advanced stage. To attenuate systemic side effects, we evaluated the effectiveness of regional chemotherapy using paclitaxel, albumin-paclitaxel, and liposome-encapsulated albumin-paclitaxel via subserosal injection in rat models employing nuclear medicine and molecular imaging technology. Method: Nine Sprague Dawley rats were divided into three groups: paclitaxel (n = 3), albumin-paclitaxel nano-particles (APNs; n = 3), and liposome-encapsulated APNs (n = 3). [123I]Iodo-paclitaxel ([123I]I-paclitaxel) was synthesized by conventional electrophilic radioiodination using tert-butylstannyl substituted paclitaxel as the precursor. Albumin-[123I]iodo-paclitaxel nanoparticles ([123I]APNs) were prepared using a desolvation technique. Liposome-encapsulated APNs (L-[123I]APNs) were prepared by thin-film hydration using DSPE-PEG2000, HSPC, and cholesterol. The rats in each group were injected with each test drug into the subserosa of the stomach antrum. After predetermined times (30 min, 2, 4, 8 h, and 24 h), molecular images of nuclear medicine were acquired using single-photon emission computed tomography/computed tomography. Results: Paclitaxel, APNs, and L-APNs showed a high cumulative distribution in the stomach, with L-APNs showing the largest area under the curve. Most drugs administered via the gastric subserosal route are distributed in the stomach and intestines, with a low uptake of less than 1% in other major organs. The time to reach the maximum concentration in the intestine for L-APNs, paclitaxel, and APNs was 6.67, 5.33, and 4.00 h, respectively. Conclusion: These preliminary results imply that L-APNs have the potential to serve as a novel paclitaxel preparation method for the regional treatment of gastric cancer.

Protocol for a double-blind placebo-controlled randomised controlled trial assessing the impact of oral semaglutide in amyloid positivity (ISAP) in community dwelling UK adults.

INTRODUCTION: Glucagon-like peptide-1 receptor agonists (GLP-1 RAs), currently marketed for type 2 diabetes and obesity, may offer novel mechanisms to delay or prevent neurotoxicity associated with Alzheimer's disease (AD). The impact of semaglutide in amyloid positivity (ISAP) trial is investigating whether the GLP-1 RA semaglutide reduces accumulation in the brain of cortical tau protein and neuroinflammation in individuals with preclinical/prodromal AD. METHODS AND ANALYSIS: ISAP is an investigator-led, randomised, double-blind, superiority trial of oral semaglutide compared with placebo. Up to 88 individuals aged ≥55 years with brain amyloid positivity as assessed by positron emission tomography (PET) or cerebrospinal fluid, and no or mild cognitive impairment, will be randomised. People with the low-affinity binding variant of the rs6971 allele of the Translocator Protein 18 kDa (TSPO) gene, which can interfere with interpreting TSPO PET scans (a measure of neuroinflammation), will be excluded.At baseline, participants undergo tau, TSPO PET and MRI scanning, and provide data on physical activity and cognition. Eligible individuals are randomised in a 1:1 ratio to once-daily oral semaglutide or placebo, starting at 3 mg and up-titrating to 14 mg over 8 weeks. They will attend safety visits and provide blood samples to measure AD biomarkers at weeks 4, 8, 26 and 39. All cognitive assessments are repeated at week 26. The last study visit will be at week 52, when all baseline measurements will be repeated. The primary end point is the 1-year change in tau PET signal. ETHICS AND DISSEMINATION: The study was approved by the West Midlands-Edgbaston Research Ethics Committee (22/WM/0013). The results of the study will be disseminated through scientific presentations and peer-reviewed publications. TRIAL REGISTRATION NUMBER: ISRCTN71283871.

Cloud-based serverless computing enables accelerated monte carlo simulations for nuclear medicine imaging.

Objective.This study investigates the potential of cloud-based serverless computing to accelerate Monte Carlo (MC) simulations for nuclear medicine imaging tasks. MC simulations can pose a high computational burden-even when executed on modern multi-core computing servers. Cloud computing allows simulation tasks to be highly parallelized and considerably accelerated.Approach.We investigate the computational performance of a cloud-based serverless MC simulation of radioactive decays for positron emission tomography imaging using Amazon Web Service (AWS) Lambda serverless computing platform for the first time in scientific literature. We provide a comparison of the computational performance of AWS to a modern on-premises multi-thread reconstruction server by measuring the execution times of the processes using between105and2·1010simulated decays. We deployed two popular MC simulation frameworks-SimSET and GATE-within the AWS computing environment. Containerized application images were used as a basis for an AWS Lambda function, and local (non-cloud) scripts were used to orchestrate the deployment of simulations. The task was broken down into smaller parallel runs, and launched on concurrently running AWS Lambda instances, and the results were postprocessed and downloaded via the Simple Storage Service.Main results.Our implementation of cloud-based MC simulations with SimSET outperforms local server-based computations by more than an order of magnitude. However, the GATE implementation creates more and larger output file sizes and reveals that the internet connection speed can become the primary bottleneck for data transfers. Simulating 109decays using SimSET is possible within 5 min and accrues computation costs of about $10 on AWS, whereas GATE would have to run in batches for more than 100 min at considerably higher costs.Significance.Adopting cloud-based serverless computing architecture in medical imaging research facilities can considerably improve processing times and overall workflow efficiency, with future research exploring additional enhancements through optimized configurations and computational methods.

The Role of Fibroblast Activation Protein Inhibitor Positron Emission Tomography in Inflammatory and Infectious Diseases: An Updated Systematic Review.

The role of fibroblast activation protein inhibitor (FAPI) positron emission tomography/computed tomography (PET/CT) is emerging for the assessment of non-oncological diseases, such as inflammatory and infectious diseases, even if the evidence in the literature is still in its initial phases. We conducted a systematic search of Scopus, PubMed/MEDLINE, Embase, and Cochrane library databases for studies published before 31 December 2023 reporting infectious and inflammatory disease imaging with FAPI PET/CT. We included twenty-one studies for a total of 1046 patients. The most frequent disease studied was lung interstitial disease, investigated in six studies for a total of 200 patients, followed by bone and joint diseases in two studies and 185 patients, IgG4-related disease in 53 patients, and Crohn's disease in 30 patients. Despite the heterogeneity of studies in terms of study design and technical features, FAPI PET/CT showed a high detection rate and diagnostic role. Moreover, when compared with 2-[18F]FDG PET/CT (n = 7 studies), FAPI PET/CT seems to have better diagnostic performances. The presence of chronic inflammation and tissue remodeling, typical of immune-mediated inflammatory conditions, may be the underlying mechanism of FAPI uptake.

Towards Clinical Development of Scandium Radioisotope Complexes for Use in Nuclear Medicine: Encouraging Prospects with the Chelator 1,4,7,10-Tetraazacyclododecane-1,4,7,10-tetraacetic Acid (DOTA) and Its Analogues.

Scandium (Sc) isotopes have recently attracted significant attention in the search for new radionuclides with potential uses in personalized medicine, especially in the treatment of specific cancer patient categories. In particular, Sc-43 and Sc-44, as positron emitters with a satisfactory half-life (3.9 and 4.0 h, respectively), are ideal for cancer diagnosis via Positron Emission Tomography (PET). On the other hand, Sc-47, as an emitter of beta particles and low gamma radiation, may be used as a therapeutic radionuclide, which also allows Single-Photon Emission Computed Tomography (SPECT) imaging. As these scandium isotopes follow the same biological pathway and chemical reactivity, they appear to fit perfectly into the "theranostic pair" concept. A step-by-step description, initiating from the moment of scandium isotope production and leading up to their preclinical and clinical trial applications, is presented. Recent developments related to the nuclear reactions selected and employed to produce the radionuclides Sc-43, Sc-44, and Sc-47, the chemical processing of these isotopes and the main target recovery methods are also included. Furthermore, the radiolabeling of the leading chelator, 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA), and its structural analogues with scandium is also discussed and the advantages and disadvantages of scandium complexation are evaluated. Finally, a review of the preclinical studies and clinical trials involving scandium, as well as future challenges for its clinical uses and applications, are presented.