Frontiers in nuclear medicine (Lausanne, Switzerland)最新文献

{"title":"Generalizable preconditioning strategies for MAP PET reconstruction using Poisson likelihood.","authors":"Matteo N Colombo, Marco Paganoni, Luca Presotto","doi":"10.3389/fnume.2025.1661332","DOIUrl":"10.3389/fnume.2025.1661332","url":null,"abstract":"<p><strong>Introduction: </strong>The positron emission tomography (PET) problem with Poisson log-likelihood is notoriously ill-conditioned. This stems from its dependence on the inverse of the measured counts and the square of the attenuation factors, causing the diagonal of the Hessian to span over 5 orders of magnitude. Optimization is, therefore, slow, motivating decades of research into acceleration techniques. In this paper, we propose a novel preconditioner tailored for maximum <i>a posteriori</i> (MAP) PET reconstruction priors that is designed to achieve approximately uniform spatial resolution.</p><p><strong>Methods: </strong>Our approach decomposes the Hessian into two components: one diagonal and one circulant. The diagonal term is the Hessian expectation computed in an initial solution estimate. As the circulant term, we use an apodized 2D ramp filter. We evaluated our method on the PET Rapid Image reconstruction Challenge dataset that includes a wide range of phantoms, scanner models, and count levels. We also varied the regularization strengths. Our preconditioner was implemented in a conjugate gradient descent algorithm without subsets or stochastic acceleration.</p><p><strong>Results: </strong>We show that the proposed preconditioner consistently achieves convergence in fewer than 10 full iterations-each consisting of just one forward and one backward projection. We also show that the circulant component, despite its crude 2D approximation, provides very meaningful acceleration beyond the diagonal-only case.</p><p><strong>Discussion: </strong>These results demonstrate that decomposing the Hessian into diagonal and circulant components is an effective strategy for accelerating MAP PET reconstruction. The proposed preconditioner significantly improves convergence speed in challenging, ill-conditioned Poisson PET inverse problems.</p>","PeriodicalId":73095,"journal":{"name":"Frontiers in nuclear medicine (Lausanne, Switzerland)","volume":"5 ","pages":"1661332"},"PeriodicalIF":1.4,"publicationDate":"2025-12-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12705633/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145775469","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Comparative dosimetric evaluation of 68Ga-PSMA and 18F-Choline PET/CT imaging in prostate cancer: implications for radiation safety and SUVmax correlation.","authors":"Hussein R Kaafarani, Mohamad Haidar, Hanna El-Balaa","doi":"10.3389/fnume.2025.1702390","DOIUrl":"10.3389/fnume.2025.1702390","url":null,"abstract":"<p><strong>Background: </strong>Comparative patient dosimetry for diagnostic PET/CT can guide radiation-safety procedures and tracer selection in prostate cancer. We compared [^68Ga]Ga-PSMA-11 and ^18F-choline PET/CT and examined whether kidney SUVmax predicts patient effective dose (ED).</p><p><strong>Methods: </strong>Prospective single-center study of consecutive men undergoing clinically indicated PET/CT: 70 ^68Ga-PSMA-11 and 70 ^18F-choline examinations (Jan 2022-Dec 2023). Dose-rate measurements were recorded at the injection site and at 1 m, immediately post-injection and at 1 h. ED was derived from literature-based tracer coefficients (h_PSMA-11 = 0.0169 mSv/MBq; h_F-choline = 0.0173 mSv/MBq). Kidney SUVmax was extracted in a subset (<i>n</i> = 40 per tracer) to test ED-SUVmax associations (Pearson's <i>r</i>).</p><p><strong>Results: </strong>Mean surface dose rate was higher with ^68Ga-PSMA vs. ^18F-choline (4.9 ± 0.8 vs. 4.5 ± 0.7 µSv·h^- ¹; <i>p</i> = 0.004). At 1 m, the difference persisted but was smaller (1.9 ± 0.3 vs. 1.7 ± 0.3 µSv·h^- ¹; <i>p</i> = 0.02). Effective dose (ED) was similar between tracers (21.3 ± 3.6 vs. 20.7 ± 3.4 mSv; <i>p</i> = 0.28). SUVmax correlated with ED for ^68Ga-PSMA (<i>r</i> = 0.71; <i>p</i> < 0.001), but not for ^18F-choline (<i>r</i> = -0.12; <i>p</i> = 0.46).</p><p><strong>Conclusions: </strong>^68Ga-PSMA yields slightly higher dose-rate readings than ^18F-choline, while overall ED is comparable. These exploratory correlations do not support SUVmax as a stand-alone safety surrogate or outcome predictor.</p>","PeriodicalId":73095,"journal":{"name":"Frontiers in nuclear medicine (Lausanne, Switzerland)","volume":"5 ","pages":"1702390"},"PeriodicalIF":1.4,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12741963/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145851648","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"First positronium lifetime imaging with scandium-44 on a long axial field-of-view PET/CT.","authors":"Lorenzo Mercolli, William M Steinberger, Pascal V Grundler, Anzhelika Moiseeva, Saverio Braccini, Maurizio Conti, Paweł Moskal, Narendra Rathod, Axel Rominger, Hasan Sari, Roger Schibli, Robert Seifert, Kuangyu Shi, Ewa Ł Stepień, Nicholas P van der Meulen","doi":"10.3389/fnume.2025.1648621","DOIUrl":"10.3389/fnume.2025.1648621","url":null,"abstract":"<p><strong>Purpose: </strong>The physical properties of ⁴⁴Sc, combined with its imminent clinical application, position it as a prime candidate for <i>in vivo</i> positronium lifetime imaging. In this study, we investigate the count statistics for ortho-positronium (oPs) measurements with ⁴⁴Sc on a commercial long-axial field-of-view (LAFOV) PET/CT.</p><p><strong>Method: </strong>A NEMA image quality phantom was filled with 41.7 MBq of ⁴⁴Sc dissolved in water and scanned on a LAFOV PET/CT. Three-photon events were identified using a prototype feature of the scanner and dedicated software. The lifetime of oPs was determined in the phantom spheres and in <math><mn>4</mn> <mo>×</mo> <mn>4</mn> <mo>×</mo> <mn>4</mn></math> mm³ voxels.</p><p><strong>Results: </strong>All measured oPs lifetimes are compatible, within the uncertainties, with the literature values for water. The oPs lifetime is <math><mn>2.65</mn> <mo>±</mo> <mn>0.50</mn></math> , <math><mn>1.39</mn> <mo>±</mo> <mn>0.20</mn></math> and <math><mn>1.76</mn> <mo>±</mo> <mn>0.18</mn></math> ns in the three smallest spheres of the phantom and <math><mn>1.79</mn> <mo>±</mo> <mn>0.57</mn></math> ns for a single voxel in the central region of the largest sphere. The relative standard deviation in the background regions of the time difference distributions, i.e., for time differences smaller than <math><mo>-</mo> <mn>2.7</mn></math> ns, is above 20%-even for voxels inside the phantom spheres.</p><p><strong>Conclusions: </strong>Despite the favorable physical properties of ⁴⁴Sc, the count statistics of three-photon events remains a challenge. The high prompt-photon energy causes a significant amount of random three-photon coincidences with the given methodology and, therefore, increases the statistical uncertainties on the measured oPs lifetime.</p>","PeriodicalId":73095,"journal":{"name":"Frontiers in nuclear medicine (Lausanne, Switzerland)","volume":"5 ","pages":"1648621"},"PeriodicalIF":1.4,"publicationDate":"2025-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12675369/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145703133","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Case Report: ¹⁸F-Fluorocholine PET/CT for detecting brown tumours in patients with hyperparathyroidism: a short case series and literature review.","authors":"J Zhang-Yin, Emmanouil Panagiotidis","doi":"10.3389/fnume.2025.1693642","DOIUrl":"10.3389/fnume.2025.1693642","url":null,"abstract":"<p><strong>Introduction: </strong>Brown tumours (BTs), also known as osteitis fibrosa cystica, are benign osteolytic lesions associated with hyperparathyroidism (HPT). BTs are cured by correcting the hypercalcaemia and HPT, which often requires surgical resection of the parathyroid adenoma. ¹⁸F-fluorocholine (FCH) PET/CT is becoming an effective tool for detecting parathyroid adenomas in cases of hyperparathyroidism. This study aims to evaluate the role of FCH PET/CT in detecting brown tumours in patients with hyperparathyroidism.</p><p><strong>Clinical cases: </strong>Three cases are presented to demonstrate the effectiveness of FCH PET/CT in detecting BTs in patients presenting with clinical and biochemical signs of HPT with suspicion of BTs.</p><p><strong>Literature review: </strong>A literature review aimed to summarize the bibliographic evidence on the use of this technique in this setting, which is relatively innovative.</p><p><strong>Conclusion: </strong>FCH PET/CT appears to be a useful tool for detecting BTs, and further prospective studies are needed to confirm this.</p>","PeriodicalId":73095,"journal":{"name":"Frontiers in nuclear medicine (Lausanne, Switzerland)","volume":"5 ","pages":"1693642"},"PeriodicalIF":1.4,"publicationDate":"2025-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12634655/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145590042","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Editorial: Rising stars in PET and SPECT: 2024.","authors":"Mario Petretta","doi":"10.3389/fnume.2025.1723945","DOIUrl":"https://doi.org/10.3389/fnume.2025.1723945","url":null,"abstract":"","PeriodicalId":73095,"journal":{"name":"Frontiers in nuclear medicine (Lausanne, Switzerland)","volume":"5 ","pages":"1723945"},"PeriodicalIF":1.4,"publicationDate":"2025-11-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12620350/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145552197","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"PET/CT imaging of bone disorders in dysparathyroidism: a comprehensive review.","authors":"E Panagiotidis, G Angelidis, V Valotassiou, I Tsougos, P Georgoulias, J T Zhang-Yin","doi":"10.3389/fnume.2025.1645497","DOIUrl":"10.3389/fnume.2025.1645497","url":null,"abstract":"<p><p>Parathyroid disorders profoundly affect bone metabolism, often long before structural damage is apparent on conventional imaging. Positron emission tomography/computed tomography (PET/CT) has emerged as a transformative tool in dysparathyroidism, enabling visualization of early metabolic bone changes and accurate localization of parathyroid pathology. This review explores the pathophysiology of bone disease in hyper- and hypoparathyroidism and highlights the role of key PET radiotracers: fluorine-18 sodium fluoride ([18F]NaF), fluorine-18 fluorodeoxyglucose ([18F]FDG), fluorine-18 fluorocholine ([18F]FCH), gallium-68 prostate-specific membrane antigen ([68Ga]PSMA). Distinct imaging patterns, such as the [18F]NaF \"superscan\" in secondary hyperparathyroidism and focal uptake in brown tumors, are discussed alongside tracer-specific strengths. Clinical applications including diagnosis, monitoring response to therapy, and prognostication are examined. We also consider emerging technologies such as artificial intelligence (AI)-assisted interpretation and positron emission tomography/magnetic resonance imaging (PET/MRI) fusion imaging. As PET/CT becomes more accessible, it is likely to play an increasingly central role in the early detection and personalized management of parathyroid-related bone disease.</p>","PeriodicalId":73095,"journal":{"name":"Frontiers in nuclear medicine (Lausanne, Switzerland)","volume":"5 ","pages":"1645497"},"PeriodicalIF":1.4,"publicationDate":"2025-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12591098/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145483821","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Production of ⁶⁴Cu and ⁶⁷Cu with accelerator neutrons by deuterons and their separation from zinc.","authors":"Yasuki Nagai, Masako Kawabata, Hideya Saeki, Shoji Motoishi, Kazuyuki Hashimoto, Kazuaki Tsukada, Arata Motomura, Akio Ohta, Naoki Takashima, Shintaro Hashimoto, Masatoshi Itoh, Hidetoshi Kikunaga, Shozo Furumoto","doi":"10.3389/fnume.2025.1657125","DOIUrl":"10.3389/fnume.2025.1657125","url":null,"abstract":"<p><p>The ⁶⁴Cu/⁶⁷Cu pair is an ideal set of theranostic radionuclides for treating patients based on their genetic profiles. We propose a novel production route for this radionuclide pair using accelerator-generated neutrons. We report experimental measurements of the absolute activity and radionuclide purity of ⁶⁴Cu and ⁶⁷Cu, produced by irradiating ⁶⁴Zn and ⁶⁸Zn with these neutrons. The measured results were consistent with simulated values. ⁶⁴Cu and ⁶⁷Cu were separated from the irradiated natural Zn and ⁶⁸Zn using sublimation and column separation techniques. The production methods for ⁶⁴Cu and ⁶⁷Cu developed in this study are expected to enhance their availability in an economically sustainable manner.</p>","PeriodicalId":73095,"journal":{"name":"Frontiers in nuclear medicine (Lausanne, Switzerland)","volume":"5 ","pages":"1657125"},"PeriodicalIF":1.4,"publicationDate":"2025-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12546246/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145380252","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Population pharmacokinetic modeling in radiopharmaceutical therapy: a review.","authors":"Deni Hardiansyah, Bisma Barron Patrianesha, Gerhard Glatting","doi":"10.3389/fnume.2025.1695332","DOIUrl":"10.3389/fnume.2025.1695332","url":null,"abstract":"<p><p>Population pharmacokinetic (PopPK) has emerged as a robust framework for characterizing inter-individual variability in the absorbed dose estimates in radiopharmaceutical therapy (RPT). By enabling the analysis of biokinetic data from heterogeneous patient populations, PopPK allows individualized absorbed dose estimates while simultaneously leveraging population-level information. This review presents and evaluates the current applications of PopPK, such as nonlinear mixed-effects modeling (NLMEM) and Bayesian fitting methods in RPT, emphasizing its advantages over traditional individual-based modeling approaches. We summarize key studies that have implemented PopPK for modeling radiopharmaceutical biokinetics, with a focus on time-integrated activity (TIA) estimation, including single-time-point (STP) dosimetry, uncertainty analysis, as well as pharmacodynamic (PD) analysis. The flexibility of PopPK in handling sparse and irregularly sampled data makes it particularly relevant for clinical scenarios where comprehensive imaging schedules are impractical. However, despite its potential, the widespread adoption of PopPK in RPT remains limited due to challenges such as computational complexity and the need for specialized expertise. This review discusses critical aspects of PopPK implementation while emphasizing the importance of interdisciplinary collaboration in translating PopPK methodologies into clinical practice. Future directions include integrating PopPK into adaptive dosimetry frameworks and applying it in STP dosimetry and PD modeling to optimize treatment personalization. By providing a comprehensive overview of PopPK applications in RPT, this review aims to facilitate the integration of advanced modeling techniques into routine clinical workflows, ultimately supporting the development of accurate and precise RPTs.</p>","PeriodicalId":73095,"journal":{"name":"Frontiers in nuclear medicine (Lausanne, Switzerland)","volume":"5 ","pages":"1695332"},"PeriodicalIF":1.4,"publicationDate":"2025-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12546074/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145380262","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Fast PET reconstruction with variance reduction and prior-aware preconditioning.","authors":"Matthias J Ehrhardt, Zeljko Kereta, Georg Schramm","doi":"10.3389/fnume.2025.1641215","DOIUrl":"10.3389/fnume.2025.1641215","url":null,"abstract":"<p><p>We investigated subset-based optimization methods for positron emission tomography (PET) image reconstruction incorporating a regularizing prior. PET reconstruction methods that use a prior, such as the relative difference prior (RDP), are of particular relevance because they are widely used in clinical practice and have been shown to outperform conventional early-stopped and post-smoothed ordered subset expectation maximization. Our study evaluated these methods using both simulated data and real brain PET scans from the 2024 PET Rapid Image Reconstruction Challenge (PETRIC), where the main objective was to achieve RDP-regularized reconstructions as fast as possible, making it an ideal benchmark. Our key finding is that incorporating the effect of the prior into the preconditioner is crucial for ensuring fast and stable convergence. In extensive simulation experiments, we compared several stochastic algorithms-including stochastic gradient descent (SGD), stochastic averaged gradient amelioré (SAGA), and stochastic variance reduced gradient (SVRG)-under various algorithmic design choices and evaluated their performance for varying count levels and regularization strengths. The results showed that SVRG and SAGA outperformed SGD, with SVRG demonstrating a slight overall advantage. The insights gained from these simulations directly contributed to the design of our submitted algorithms, which formed the basis of the winning contribution to the PETRIC 2024 challenge.</p>","PeriodicalId":73095,"journal":{"name":"Frontiers in nuclear medicine (Lausanne, Switzerland)","volume":"5 ","pages":"1641215"},"PeriodicalIF":1.4,"publicationDate":"2025-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12484155/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145214615","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Platinum group metals for nuclear medicine, a luxurious dream or the future of imaging and therapy: a review.","authors":"Daniel G Racz, Ivis F Chaple","doi":"10.3389/fnume.2025.1656374","DOIUrl":"10.3389/fnume.2025.1656374","url":null,"abstract":"<p><p>Platinum group metals (PGMs) consist of six transition metals: platinum (Pt), palladium (Pd), rhodium (Rh), osmium (Os), iridium (Ir), and ruthenium (Ru). PGMs have been used notably in industrial, electronic, and medical applications. For example, Ir-192 is often utilized in industry to detect structural defects in metal and assess pipeline integrity. Pd-104 is irradiated to produce Pd-103 seeds, used for prostate cancer treatment. Other isotopes of elements in this group can be sourced to facilitate critical applications, discussed in this review. Due to their unique chemical and nuclear properties, these metals may be promising candidates for various nuclear medicine applications, including diagnostic imaging via Positron Emission Tomography (PET), Single Photon Emission Computed Tomography (SPECT) and Targeted Radionuclide Therapy (TRT). This review will explore PGMs in nuclear medicine, focusing on their production routes, nuclear characteristics, and suitability for past and future development of radiopharmaceuticals. We will highlight methods for radiochemical separation and purification of each radionuclide, discussing potential challenges and emphasizing the need for further research to ensure sustainability. As the demand for advanced nuclear medicine techniques continues to grow, PGMs may play a significant role in addressing current challenges in the field. We will discuss several radionuclides of interest to nuclear medicine including ¹⁹¹Pt, ^193mPt, ^195mPt, ¹⁰³Pd, ¹⁰⁹Pd, ^103mRh, ¹⁰⁵Rh, ¹⁹¹Os, ¹⁹²Ir, ⁹⁷Ru, and ¹⁰³Ru.</p>","PeriodicalId":73095,"journal":{"name":"Frontiers in nuclear medicine (Lausanne, Switzerland)","volume":"5 ","pages":"1656374"},"PeriodicalIF":1.4,"publicationDate":"2025-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12460398/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145187663","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}