Whole Gamma Imaging: Challenges and Opportunities.

Compton imaging has been recognized as a possible nuclear medicine imaging method following the establishment of SPECT and PET. Whole gamma imaging (WGI), a combination of PET and Compton imaging, could be the first practical method to bring out the potential of Compton imaging in nuclear medicine. With the use of such positron emitters as 89Zr and 44Sc, WGI may enable highly sensitive imaging of antibody drugs for early tumor detection and quantitative hypoxia imaging for effective tumor treatment. Some of these concepts have been demonstrated preliminarily in physics experiments and small animal imaging tests with a developed WGI prototype.

Artificial Intelligence-powered automatic volume calculation in medical images - available tools, performance and challenges for nuclear medicine.

Volumetry is crucial in oncology and endocrinology, for diagnosis, treatment planning, and evaluating response to therapy for several diseases. The integration of Artificial Intelligence (AI) and Deep Learning (DL) has significantly accelerated the automatization of volumetric calculations, enhancing accuracy and reducing variability and labor. In this review, we show that a high correlation has been observed between Machine Learning (ML) methods and expert assessments in tumor volumetry; Yet, it is recognized as more challenging than organ volumetry. Liver volumetry has shown progression in accuracy with a decrease in error. If a relative error below 10 % is acceptable, ML-based liver volumetry can be considered reliable for standardized imaging protocols if used in patients without major anomalies. Similarly, ML-supported automatic kidney volumetry has also shown consistency and reliability in volumetric calculations. In contrast, AI-supported thyroid volumetry has not been extensively developed, despite initial works in 3D ultrasound showing promising results in terms of accuracy and reproducibility. Despite the advancements presented in the reviewed literature, the lack of standardization limits the generalizability of ML methods across diverse scenarios. The domain gap, i. e., the difference in probability distribution of training and inference data, is of paramount importance before clinical deployment of AI, to maintain accuracy and reliability in patient care. The increasing availability of improved segmentation tools is expected to further incorporate AI methods into routine workflows where volumetry will play a more prominent role in radionuclide therapy planning and quantitative follow-up of disease evolution.

Nanoparticles based on MIL-101 metal-organic frameworks as efficient carriers of therapeutic188Re radionuclide for nuclear medicine.

Nuclear medicine presents one of the most promising modalities for efficient non-invasive treatment of a variety of cancers, but the application of radionuclides in cancer therapy and diagnostics is severely limited by their nonspecific tissue accumulation and poor biocompatibility. Here, we explore the use of nanosized metal-organic frameworks (MOFs) as carriers of radionuclides to order to improve their delivery to tumour. To demonstrate the concept, we prepared polymer-coated MIL-101(Cr)-NH2MOFs and conjugated them with clinically utilized radionuclide188Re. The nanoparticles demonstrated high loading efficacy of radionuclide reaching specific activity of 49 MBq mg-1. Pharmacokinetics of loaded MOFs was investigated in mice bearing colon adenocarcinoma. The biological half-life of the radionuclide in blood was (20.9 ± 1.3) h, and nanoparticles enabled it to passively accumulate and retain in the tumour. The radionuclide delivery with MOFs led to a significant decrease of radioactivity uptake by the thyroid gland and stomach as compared with perrhenate salt injection, which is beneficial for reducing the side toxicity of nuclear therapy. The reported data on the functionalization and pharmacokinetics of MIL-101(Cr)-NH2for radionuclide delivery unveils the promising potential of these MOFs for nuclear medicine.

Clinical Applications of Radiomics in Nuclear Medicine.

Radiomics is an emerging field of artificial intelligence that focuses on the extraction and analysis of quantitative features such as intensity, shape, texture and spatial relationships from medical images. These features, often imperceptible to the human eye, can reveal complex patterns and biological insights. They can also be combined with clinical data to create predictive models using machine learning to improve disease characterization in nuclear medicine. This review article examines the current state of radiomics in nuclear medicine and shows its potential to improve patient care. Selected clinical applications for diseases such as cancer, neurodegenerative diseases, cardiovascular problems and thyroid diseases are examined. The article concludes with a brief classification in terms of future perspectives and strategies for linking research findings to clinical practice.

A Brief History of Nuclear Medicine Imaging of Infection.

For nearly 50 years, nuclear medicine has played an important role in the diagnosis of infection. Gallium citrate Ga 67 was one of the first, if not the first, radionuclide used for this purpose. Unfavorable imaging characteristics, a lack of specificity, and the long interval (2-3 days) between administration and imaging spurred the search for alternatives. At the present time, gallium 67 citrate is used primarily for differentiating acute tubular necrosis from interstitial nephritis and as an alternative for indications including sarcoid, spondylodiscitis, and fever of unknown origin, when 18F-fluorodeoxyglucose (18F-FDG) is not available. The approval, in the mid-1980s, of techniques for in vitro labeling of leukocytes with indium-111 and technetium-99m that subsequently migrate to foci of infection was a significant advance in nuclear medicine imaging of infection and labeled leukocyte imaging still plays an important role in imaging of infection. There are significant disadvantages to in vitro labeled leukocyte imaging. Unfortunately, efforts devoted to developing in vivo leukocyte labeling methods have met with only limited success. Over the past 20 years 18F-FDG has established itself as a valuable imaging agent for musculoskeletal and cardiovascular infections, as well as sarcoidosis and fever of unknown origin. As useful as these agents are, their uptake is based on the host response to infection, not infection itself. Previous attempts at developing infection-specific agents, including radiolabeled antibiotics and vitamins, were limited by poor results and/or lack of availability, so investigators continue to focus on developing infection-specific nuclear medicine imaging agents.

The impact of COVID-19 on open access publishing in radiology and nuclear medicine: an in-depth analysis.

In response to the COVID-19 pandemic, numerous initiatives have been implemented to ensure open access availability of COVID-19-related articles to make published articles accessible for anyone. This study aimed to assess the impact of the COVID-19 pandemic on open-access publishing in radiology and nuclear medicine. We conducted a comprehensive analysis of articles and reviews published in these fields during the COVID-19 publishing era using the Web of Science database. We analyzed several indicators between COVID-19 and non-COVID-19 related articles, including the number and percentage of open-access articles, the top ten cited articles, and the number of reviews. In total, 67,100 articles were published in radiology and nuclear medicine between January 2020 and June 2022. Among those, more than half (51.1%) were open-access articles. Among these publications, 2,336 were COVID-19-related, and 64,764 were non-COVID-19-related. However, articles related to COVID-19 had an open access rate of 91.5%, compared to only 49.6% of the non-COVID-19-related articles. Moreover, COVID-19-related articles had a higher percentage of highly cited and hot papers compared to articles not related to COVID-19. Moreover, most highly cited studies were related to chest computerized tomography (CT) scan findings in COVID-19 patients. The findings emphasize the significant proportion of open access COVID-19-related publications in radiology and nuclear medicine, facilitating widespread and timely access to everyone.

Evaluation of the contamination droplet model used for the assessment of skin dose during the manipulation of radiopharmaceuticals.

The manipulation of radiopharmaceuticals in nuclear medicine can result in the droplet contamination of operators resulting in the accumulation of a significant skin dose. Current methods to estimate this skin dose often utilise a 50µl cylindrical droplet model, which can lead to unrealistically high estimated skin doses for some radiopharmaceuticals. By conducting experiments to measure the volume of real droplets arising from simulating the manipulation of radiopharmaceuticals, this work found that 50µl is an overestimation of a realistic contamination droplet. For almost all radiopharmaceuticals considered in this work, incorporating a smaller droplet volume into skin dose simulations resulted in higher estimates of skin dose rate per unit of activity, which, when combined with appropriate activity concentrations and droplet volumes, resulted in lower skin doses for contamination droplet incidents. The results presented in this work challenge the 50µl contamination droplet volume and highlight the importance of having an accurate model when estimating the skin dose for contamination scenarios.

Contribución de la medicina nuclear en la cirugía de precisión en el cáncer de mama / Nuclear medicine contribution to precision surgery in breast cancer

La medicina nuclear ha contribuido significativamente en la cirugía de precisión en el cáncer de mama en las últimas décadas. La cirugía radioguiada (CRG) ha permitido la biopsia del ganglio centinela (GC) en la evaluación de la infiltración ganglionar regional modificando el manejo de pacientes con cáncer de mama precoz. Para la axila, el procedimiento de la biopsia del GC ha significado un decremento de complicaciones y una mejor calidad de vida en comparación con la disección de los ganglios linfáticos axilares. Originalmente, la biopsia del GC se indicó principalmente en tumores cT1-2, sin evidencia de metástasis en los ganglios linfáticos axilares. Sin embargo, en los últimos años la biopsia del GC también se está ofreciendo a pacientes con tumores grandes o multifocales, carcinoma ductal in situ, recidiva del cáncer de mama ipsilateral y a pacientes que reciben tratamiento sistémico neoadyuvante (TSN) para cirugía conservadora de mama. Paralelamente a esta evolución, varias asociaciones científicas están tratando de homogeneizar cuestiones como la elección del radiotrazador, el lugar de inyección de la mama, la estandarización de las imágenes preoperatorias y el momento de la biopsia del GC en relación con el TSN, así como el manejo de las metástasis no axilares del GC (p. ej., cadena mamaria interna). Además, la CRG se usa actualmente para lograr la extirpación de tumores de mama primarios mediante inyección intralesional de radiocoloides o mediante implantación de semillas de yodo radiactivo que también se emplean para marcar los ganglios linfáticos axilares metastásicos. Este último procedimiento contribuye a manejar la axila con ganglios positivos en combinación con la PET/TC con [18F]FDG en un esfuerzo por adaptar el tratamiento sistémico y locorregional (AU)

Nuclear medicine has significantly contributed to precision surgery in breast cancer in the past decades. Radioguided surgery (RGS) has enabled sentinel node (SN) biopsy in assessing regional nodal involvement modifying the management of patients with early breast cancer. For the axilla the SN procedure has resulted in fewer complications and better quality of life when compared with axillary lymph node dissection. Originally, SN biopsy principally concerned cT1-2 tumors without evidence of axillary lymph node metastases. However, in last years SN biopsy is also being offered to patients with large or multifocal tumors, ductal carcinoma in situ, ipsilateral breast cancer relapse, and to patients receiving neoadjuvant systemic treatment (NST) for breast sparing surgery. Parallel to this evolution various scientific associations are trying to homogenise issues such as radiotracer choice, breast injection site, preoperative imaging standardisation and SN biopsy timing in relation to NST as well as management of non-axillary SN metastasis (e.g. internal mammary chain). Additionally, RGS is currently used to accomplish primary breast tumour excision either by intralesional radiocolloid injection or by radioactive iodine seed implantation which is also employed to target metastatic axillary lymph nodes. This latter procedure contributes to manage the node-positive axilla in combination with 18F-FDG PET/CT in an effort to tailor systemic and loco regional treatment (AU)

Theranostic Nuclear Medicine with Gallium-68, Lutetium-177, Copper-64/67, Actinium-225, and Lead-212/203 Radionuclides.

Molecular changes in malignant tissue can lead to an increase in the expression levels of various proteins or receptors that can be used to target the disease. In oncology, diagnostic imaging and radiotherapy of tumors is possible by attaching an appropriate radionuclide to molecules that selectively bind to these target proteins. The term "theranostics" describes the use of a diagnostic tool to predict the efficacy of a therapeutic option. Molecules radiolabeled with γ-emitting or ß+-emitting radionuclides can be used for diagnostic imaging using single photon emission computed tomography or positron emission tomography. Radionuclide therapy of disease sites is possible with either α-, ß-, or Auger-emitting radionuclides that induce irreversible damage to DNA. This Focus Review centers on the chemistry of theranostic approaches using metal radionuclides for imaging and therapy. The use of tracers that contain ß+-emitting gallium-68 and ß-emitting lutetium-177 will be discussed in the context of agents in clinical use for the diagnostic imaging and therapy of neuroendocrine tumors and prostate cancer. A particular emphasis is then placed on the chemistry involved in the development of theranostic approaches that use copper-64 for imaging and copper-67 for therapy with functionalized sarcophagine cage amine ligands. Targeted therapy with radionuclides that emit α particles has potential to be of particular use in late-stage disease where there are limited options, and the role of actinium-225 and lead-212 in this area is also discussed. Finally, we highlight the challenges that impede further adoption of radiotheranostic concepts while highlighting exciting opportunities and prospects.

Enhancing Interoperability and Harmonisation of Nuclear Medicine Image Data and Associated Clinical Data.

Nuclear imaging techniques such as positron emission tomography (PET) and single photon emission computed tomography (SPECT) in combination with computed tomography (CT) are established imaging modalities in clinical practice, particularly for oncological problems. Due to a multitude of manufacturers, different measurement protocols, local demographic or clinical workflow variations as well as various available reconstruction and analysis software, very heterogeneous datasets are generated. This review article examines the current state of interoperability and harmonisation of image data and related clinical data in the field of nuclear medicine. Various approaches and standards to improve data compatibility and integration are discussed. These include, for example, structured clinical history, standardisation of image acquisition and reconstruction as well as standardised preparation of image data for evaluation. Approaches to improve data acquisition, storage and analysis will be presented. Furthermore, approaches are presented to prepare the datasets in such a way that they become usable for projects applying artificial intelligence (AI) (machine learning, deep learning, etc.). This review article concludes with an outlook on future developments and trends related to AI in nuclear medicine, including a brief research of commercial solutions.