EJNMMI Physics最新文献

{"title":"A deep learning framework for lesion-level treatment response prediction in hodgkin lymphoma using PET/CT tensor radiomics.","authors":"Mahdie Jajroudi, Hossein Jamalirad, Milad Enferadi, Vahid Roshanravan, Farshad Emami, Parham Geramifar, Saeid Eslami","doi":"10.1186/s40658-026-00838-8","DOIUrl":"10.1186/s40658-026-00838-8","url":null,"abstract":"<p><strong>Background: </strong>Accurate prediction of treatment response in Hodgkin lymphoma (HL) is crucial for personalized therapy. The Tensor Radiomics (TR) paradigm advances traditional radiomics by producing and analyzing diverse feature variations, employing tensors computed across multiple parameter combinations to optimize radiomics feature extraction and improve tumor characterization. However, the complexity and variability of these features pose significant challenges for analysis and clinical application in HL research. This study introduces the Tensor Radiomics Network (TR-NET), a deep learning framework that automates feature selection from tensor radiomics data and predicts treatment response. It also incorporates explainable AI techniques to identify the most influential features.</p><p><strong>Methods: </strong>We analyzed 420 lesions from 70 HL patients using ¹⁸F-FDG PET/CT. Tensor radiomic feature sets were generated by varying bin widths for PET (0.2, 0.4, 0.6, 0.8) and CT (10, 25, 50) images. Extracted features encompassed first-order, shape, texture, and filter classes (Laplacian of Gaussian, Wavelet, Square, Square Root, Logarithm, Exponential, Gradient, Local Binary Pattern (LBP) 2D, LBP 3D for each lesion, totaling 13,790 features. We utilized machine learning models, including Random Forest (RF), XGBoost, Support Vector Machine (SVM), and the deep learning model TR-NET for analysis. SHAP (SHapley Additive exPlanations), an explainable AI method, was applied to interpret the predictions of the best-performing model.</p><p><strong>Results: </strong>TR-NET achieved a predictive performance, with an AUC-ROC of 0.8470 (95% CI: 0.7669-0.9185), a sensitivity of 82.2%, and a specificity of 78.2%, offering a balanced classification characteristic. In comparison, XGBoost achieved an AUC of 0.8160 (95% CI: 0.7457-0.8599), characterized by high sensitivity (93.3%) but lower specificity (66.2%), indicating a tendency towards false positives. Random Forest and SVM also showed high sensitivity (92% and 91.1%), but both suffered from significantly reduced specificity (29.5% and 51.3%).</p><p><strong>Conclusion: </strong>TR-NET demonstrates enhanced predictive accuracy and clinical relevance compared to classic machine learning, supporting personalized treatment strategies and the integration of explainable AI in oncology.</p>","PeriodicalId":11559,"journal":{"name":"EJNMMI Physics","volume":"13 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2026-06-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13269603/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148249714","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Evaluation of modified window-based scatter compensation in quantitative ¹⁷⁷Lu-SPECT for a ring-configured CZT SPECT-CT.","authors":"Irma Ceric Andelius, Anna Stenvall, Elias Nilsson, Erik Larsson, Johan Gustafsson","doi":"10.1186/s40658-026-00905-0","DOIUrl":"10.1186/s40658-026-00905-0","url":null,"abstract":"<p><strong>Background: </strong>The aim was to evaluate bias and precision for ¹⁷⁷Lu-activity-quantification using window-based scatter compensation in a ring-configured CZT gamma camera (StarGuide™, GE HealthCare). This paper extends a previous study by applying modified scatter compensation (MSC) methods introduced with the StarGuidePlus upgrade. The modified methods account for contamination of scatter windows by primary photons due to tailing. Whilst the original compensation addressed tailing in the 208 keV peak only, the upgrade extends the concept to the 113 keV peak and enables the estimated primary signal in the scatter windows to be included to the measured projections (MSC + P).</p><p><strong>Methods: </strong>Listmode-data for a NEMA phantom and anthropomorphic phantom were reframed to accommodate the updated settings for MSC and MSC + P. Reconstruction was performed using OS-EM (two to 30 iterations, 10 subsets) with compensation for attenuation, scatter (DEW/TEW, MSC and MSC + P), spatial resolution, and penetration at 208 keV. Volumes-of-interest following the manufacturer-specified sphere sizes were defined and activity-concentration was quantified for each sphere and the total phantom activity across six (10 min) time-frames. Bias was evaluated with mean relative error and precision with coefficient of variation (CV).</p><p><strong>Results: </strong>Imaging at 208 keV generally results in similar activity concentrations and total activity estimates for MSC and MSC + P (mean relative error: - 24.8 to - 23.4%, CV: 0.6 and 0.7% for the larges sphere). For 113 keV, a slightly better precision is obtained for MSC and MSC + P (mean relative error: - 15.4 and - 21.5%, CV: 0.6 and 0.7% for the largest sphere in the NEMA phantom) but a larger bias compared with TEW (mean relative error - 7.1%, CV 0.8%). The major difference is for total activity where the MSC and MSC + P decrease bias compared to TEW (5 and 4% versus 21% for 113 keV in the NEMA phantom).</p><p><strong>Conclusions: </strong>The improvement in activity-concentration accuracy in regard to bias and precision is modest in small-volume high activity-concentration regions. However, the findings suggest potential value in preservation of total activity for both MSC and MSC + P.</p>","PeriodicalId":11559,"journal":{"name":"EJNMMI Physics","volume":" ","pages":""},"PeriodicalIF":3.5,"publicationDate":"2026-06-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13272698/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148249154","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Impact of scan duration and scatter correction on quantitative accuracy in Yttrium-90 PET/CT imaging using LAFOV and SAFOV systems: a phantom and clinical evaluation.","authors":"Konstantinos G Zeimpekis, Magdalena Kulgawczuk, Carola Bregenzer, Marc Schindewolf, Christos Sachpekidis, Hasan Sari, Kalyani Pandya, Ali Afshar-Oromieh, Axel Rominger, Kuangyu Shi, Robert Seifert","doi":"10.1186/s40658-026-00907-y","DOIUrl":"10.1186/s40658-026-00907-y","url":null,"abstract":"<p><strong>Purpose: </strong>This study compared quantitative accuracy and image quality of post-radioembolization selective internal radiation therapy (SIRT) ⁹⁰Y PET/CT using a long axial field-of-view (LAFOV) and standard axial field-of-view (SAFOV) system, focusing on absolute (ABS) versus relative (RS) scatter correction. Additionally, variance modeling and logistic regression were performed to define injected-activity thresholds ensuring reliable quantification at different acquisition durations.</p><p><strong>Methods: </strong>Phantom experiments were conducted on Biograph Vision Quadra (LAFOV) and Vision 600 (SAFOV) PET/CT scanners using NEMA IQ phantoms filled with ⁹⁰Y activity. Reconstructions employed OSEM + TOF + PSF with ABS and RS scatter correction at 50 min (both scanners) and 10- and 1-minute (only for LAFOV). Metrics included NEMA recovery coefficients (RC) and background variability (BV). 44 post-SIRT patients (median age 70 y) were analyzed for image-based quantification of injected activity using whole-liver VOIs, across multiple durations (20, 15, 10, 5, 1 min). Metrics included Bland-Altman analysis, equivalence testing (± 10%), and Lin's concordance correlation coefficient (CCC). Variance-activity relationships and logistic regression quantified thresholds for 80%, 90% and 95% success probability.</p><p><strong>Results: </strong>LAFOV achieved higher RCs and ~ 3× lower BV than SAFOV. ABS yielded significantly improved accuracy and stability versus RS, particularly at short scans. Patient data acquired on the LAFOV system showed ABS quantification equivalent to injected activity within ± 10% for ≥ 5 min (CCC ≥ 0.99), whereas RS required ≥ 10 min. Variance followed a power-law decay (γ ≈ 1.5 at 5 min), and logistic regression identified an activity threshold of ~ 1.6 GBq for 90% accuracy at 5 min. At ≥ 10 min, quantification became independent of activity.</p><p><strong>Conclusion: </strong>Compared with a SAFOV 50-minute clinical routine acquisition, LAFOV PET enabled a similar BV performance at 7-times accelerated scanning duration. LAFOV PET/CT with absolute scatter correction enables accurate ⁹⁰Y quantification and dosimetry with acquisition times as short as 10 min regardless of the administered ⁹⁰Y activity, supporting efficient clinical post-SIRT imaging workflows.</p>","PeriodicalId":11559,"journal":{"name":"EJNMMI Physics","volume":" ","pages":""},"PeriodicalIF":3.5,"publicationDate":"2026-06-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13493359/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148224037","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Radiation segmentectomy with resin microspheres for hepatocellular carcinoma: a state-of-the-art review highlighting evidence gaps and future research needs.","authors":"Javier Orcajo Rincón, Laura Reguera Berenguer, Ana María Matilla Peña, Julian Ardila Mantilla, Manuel González Leyte, Miguel Echenagusia Boyra, Laura Márquez Pérez, Laura Carrión Martín, Arturo Álvarez Luque, Arturo Colón Rodríguez, Juan Carlos Alonso Farto","doi":"10.1186/s40658-026-00891-3","DOIUrl":"10.1186/s40658-026-00891-3","url":null,"abstract":"<p><strong>Introduction: </strong>Radiation segmentectomy (RS) has emerged as a promising approach for hepatocellular carcinoma (HCC), particularly when high tumor doses are achieved. While the clinical utility of ablative doses with glass microspheres is well established, data on resin microspheres remain scarce and inconsistent. This state-of-the-art review aims to provide a descriptive, hypothesis-generating overview of the available evidence and to highlight key gaps in the literature.</p><p><strong>Methods: </strong>A structured search of PubMed and Embase was conducted to identify clinical studies, technical reports, and reviews evaluating RS using resin microspheres in patients with HCC. Inclusion was limited to studies reporting dosimetric data or clinical outcomes following high-dose delivery. Both published and unpublished sources were considered to ensure a comprehensive overview.</p><p><strong>Results: </strong>Six publications met the inclusion criteria: four studies with primary clinical data and two narrative reviews. Most were retrospective and single-center, with considerable heterogeneity in methodology and outcome reporting. Reported tumor doses varied widely, and no prospective study has validated safety or efficacy thresholds to date. Nevertheless, selected studies suggest that resin microspheres may achieve tumoricidal doses (> 300 Gy), with encouraging response rates and acceptable safety profiles in highly selective settings.</p><p><strong>Conclusion: </strong>The use of resin microspheres in radiation segmentectomy represents a promising, yet underexplored, therapeutic strategy in HCC. However, the current evidence base is limited, heterogeneous, and not suitable for definitive clinical conclusions. This review is intended to frame the current evidence landscape and generate hypotheses, supporting the need for prospective, standardized investigations to define optimal dosimetry and guide future research.</p>","PeriodicalId":11559,"journal":{"name":"EJNMMI Physics","volume":" ","pages":""},"PeriodicalIF":3.5,"publicationDate":"2026-06-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13476404/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148204564","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A tissue-informed deep learning-based method for positron range correction in preclinical [Formula: see text]Ga PET imaging.","authors":"Nerea Encina-Baranda, Robert J Paneque-Yunta, Javier Lopez-Rodriguez, Edwin C Pratt, Trong Nghia Nguyen, Jan Grimm, Alejandro Lopez-Montes, Joaquin L Herraiz","doi":"10.1186/s40658-026-00900-5","DOIUrl":"10.1186/s40658-026-00900-5","url":null,"abstract":"<p><strong>Purpose: </strong>Positron range (PR) limits spatial resolution and quantitative accuracy in PET imaging, particularly for high-energy positron-emitting radionuclides such as [Formula: see text]Ga. This study proposes a deep learning-based approach using 3D residual encoder-decoder convolutional neural networks (3D RED-CNNs), incorporating tissue-dependent anatomical information through a μ-map-dependent loss function. We propose a model trained from realistic simulations and, using the information in the initial PET and CT images, obtain positron range corrected images. We validated our model in both simulations and real acquisitions.</p><p><strong>Methods: </strong>Three different 3D RED-CNN architectures-Single-Channel, Two-Channel, and DualEncoder-were trained using simulated PET datasets and evaluated on both synthetic and real PET acquisitions from [Formula: see text]Ga-FH and [Formula: see text]Ga-PSMA-617 mouse studies. The performance of each model was compared to a standard Richardson-Lucy deconvolution (RL-PRC) approach using metrics such as mean absolute error (MAE), structural similarity index (SSIM), contrast recovery (CR), and contrast-to-noise ratio (CNR).</p><p><strong>Results: </strong>In simulations, CNN-based methods achieved up to 19% improvement in SSIM and 13% reduction in MAE compared to RL-PRC. The Two-Channel model showed the highest CR and CNR values, recovering lung activity with 97% agreement to the ground truth, compared to 77% with RL-PRC. Noise remained stable for CNN models (∼5.9%), whereas RL-PRC increased noise by 5.8%. In preclinical acquisitions, the Two-Channel model achieved the highest CNR in different tissues, while maintaining the lowest noise level (9.6%). Although no ground truth was available for real data, analysis confirmed superior tumor delineation and reduced spillover artifacts with the Two-Channel model.</p><p><strong>Conclusion: </strong>These findings demonstrate the potential of CNN-based PRC for improving quantitative PET imaging, particularly for [Formula: see text]Ga. CNN-based methods, particularly the Two-Channel model, outperformed conventional deconvolution in both simulated and real data. Future work will focus on enhancing model generalization through domain adaptation and hybrid training strategies, as well as extending the method to other high-energy PET radionuclides.</p>","PeriodicalId":11559,"journal":{"name":"EJNMMI Physics","volume":" ","pages":""},"PeriodicalIF":3.5,"publicationDate":"2026-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13287517/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148194622","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"GATE Monte Carlo evaluation of cellular dosimetry for ¹¹⁹Sb in targeted radionuclide therapy.","authors":"Arsalan Hasnaki, Nahid Chegeni, Barat Barati, Ghasemali Divband, Etesam Malekzadeh","doi":"10.1186/s40658-026-00884-2","DOIUrl":"10.1186/s40658-026-00884-2","url":null,"abstract":"<p><strong>Background: </strong>This study evaluates the cellular dosimetry of Antimony-119 (¹¹⁹Sb) as a candidate for targeted radionuclide therapy (TRT), using Monte Carlo simulations with the GATE toolkit. The goal is to assess the microdosimetric characteristics of ¹¹⁹Sb as an Auger and Internal conversion electron emitter and compare its performance with other clinically relevant radionuclides-¹⁷⁷Lu, ¹²⁵I, ¹²³I, and ¹⁰³Pd-across different cellular geometries and emission spectra.</p><p><strong>Methods: </strong>Monte Carlo simulations were performed using the GATE toolkit to model energy deposition at the cellular level. Two cell geometries were considered: one with a centrally located nucleus and another with the nucleus adjacent to the cell membrane, reflecting real biological diversity. S-values (absorbed dose per decay) were calculated for three possible locations of radioactivity (nucleus, cytoplasm, and cell membrane). Three emission spectra and two physics models were used to ensure robust results. Simulations were benchmarked against established dosimetry models (MIRDcell, PENELOPE, and Geant4).</p><p><strong>Results: </strong>¹¹⁹Sb delivered the highest and most localized dose to the cell nucleus, particularly when radioactivity was at the cell membrane, outperforming the other radionuclides tested. Its S-values were up to five times higher than ¹⁷⁷Lu and four times higher than ¹²⁵I in certain configurations. This effect remained strong even when the nucleus was off-center, suggesting ¹¹⁹Sb's effectiveness is independent to nucleus locations diversities. Auger and Coster-Kronig electrons dominated the energy deposition for most isotopes in single cell configurations, while internal conversion electrons contributed significantly for ¹¹⁹Sb in the cytoplasmic and membrane configurations.</p><p><strong>Conclusions: </strong>¹¹⁹Sb is a promising candidate for TRT of micrometastases and single cancer cells due to its high and stable S-values, especially when radioactivity is localized at the cell membrane. Its dosimetric stability across nucleus positions makes it particularly suitable for therapeutic applications where cellular morphology varies. However, production and radiolabeling challenges may limit its clinical adoption.</p>","PeriodicalId":11559,"journal":{"name":"EJNMMI Physics","volume":" ","pages":""},"PeriodicalIF":3.5,"publicationDate":"2026-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13493738/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148162096","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Scan duration for dopamine transporter neuroimaging with[¹²³I]FP-CIT and a high-sensitivity multiple-pinhole SPECT/CT.","authors":"Gerda Thomsen, Karine Madsen, Cecilie A Poulsen, Claus Svarer, Lars H Pinborg, Gitte M Knudsen, Robin de Nijs","doi":"10.1186/s40658-026-00903-2","DOIUrl":"10.1186/s40658-026-00903-2","url":null,"abstract":"<p><strong>Background: </strong>Dopamine transporter (DAT) imaging with [¹²³I]FP-CIT (Ioflupane, DaTscan™) is an established diagnostic tool for diagnosing parkinsonism and usually requires 40 min. of scanning. The three-headed high-sensitivity multiple-pinhole SPECT/CT scanner with dedicated brain multi-pinhole collimators (MPH) has in many respects superior performance and potentially enables a reduced scan duration, which can be a major advantage for patients and increases the number of patient studies that can be performed in one day. The aim of this study is to determine the minimal required scan duration that still returns good image quality and diagnostic accuracy in parkinsonism.</p><p><strong>Methods: </strong>Fifty patients suspected of parkinsonism (age range 52-87 years) and 9 healthy controls (age range 57-66 years) underwent imaging with Mediso AnyScan Trio SPECT/CT and MPH collimators for 40 min. three hours after injection of 185 MBq [¹²³I]FP-CIT. The images were reconstructed using four different acquisition lengths: 10, 20, 30, and 40 min., and subsequently quantified with an automatic image-based analysis. Outcomes of the different acquisition lengths were compared by statistical analysis of the SBR-values and by visual assessment by experienced physicians.</p><p><strong>Results: </strong>Compared to 40 min. acquisitions and both in patients and healthy controls, 10 min acquisitions resulted in a significantly higher specific binding ratio (SBR) (≥ 0.5) in the striatum, putamen and caudate (p ≤ 0.001). SBR did not differ statistically significant between 30- and 40-min. acquisitions. Mean SBR difference between 20- and 40-min. scans with the 40-min. scan as a reference was 0.07 with 95% CI [-0.45, 0.59] for the striatum. Visual inspection of images showed that 20 min. acquisitions resulted in acceptable image quality (≥84% rated as sufficient).</p><p><strong>Conclusion: </strong>We find that the scan time with DAT SPECT imaging on SPECT/CT and MPH collimators can be reduced to 20 min. without compromising image quality and diagnostic outcome. A scan duration of 20 min is beneficial for both patient comfort and the clinical workflow.</p>","PeriodicalId":11559,"journal":{"name":"EJNMMI Physics","volume":" ","pages":""},"PeriodicalIF":3.5,"publicationDate":"2026-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13454077/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148155795","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The impact of scan time on dynamic [Formula: see text]-FAPI-04 total-body PET parametric imaging generated by deep learning models.","authors":"Jidong Han, Yu Liu, Meiyong Huang, Lingxin Chen, Yunlong Gao, Xinlan Yang, Jianjun Liu, Dong Liang, Zhanli Hu, Ruohua Chen, Bo Yuan","doi":"10.1186/s40658-026-00895-z","DOIUrl":"10.1186/s40658-026-00895-z","url":null,"abstract":"<p><strong>Purpose: </strong>To date, some studies have employed deep learning techniques to directly generate dynamic positron emission tomography (PET) parametric images from static PET. Compared with traditional methods, this approach requires only a single PET/computed tomography (CT) scan. However, current methods tend to employ static PET images captured at fixed scanning times without considering whether static PET images acquired at different scanning times impact the quality of the dynamic PET parametric images generated via deep learning.</p><p><strong>Methods: </strong>A single-frame image from dynamic [Formula: see text]-FAPI-04 total-body PET can actually be regarded as a static PET image acquired during that specific period of the PET/CT scan. We extracted 5 frames of dynamic [Formula: see text]-FAPI-04 total-body PET at equal intervals, specifically frames 50, 76, 80, 86, and 92. Each frame of the dynamic [Formula: see text]-FAPI-04 total-body PET images was subsequently input into the deep learning model to obtain dynamic [Formula: see text]-FAPI-04 total-body PET parametric images. By comparing and analyzing the quality of dynamic PET parametric images, we attempted to determine the optimal scan time for static PET.</p><p><strong>Results: </strong>The experimental results revealed that the dynamic [Formula: see text]-FAPI-04 total-body PET parametric image generated from the 58th frame of the dynamic PET image via the deep learning model exhibited the poorest performance. This may be because the diffusion of the radioactive tracer was not stable at the time of PET/CT scanning in frame 58, but it was relatively stable from frames 70-92.</p><p><strong>Conclusion: </strong>Static PET images acquired at different scanning times do indeed affect the quality of the dynamic [Formula: see text]-FAPI-04 total-body PET parametric images generated via deep learning. Specifically, when the radioactive tracer is unstable during the early stage of scanning, the quality of the dynamic [Formula: see text]-FAPI-04 total-body PET parametric images generated from static PET images via deep learning appears to be inferior.</p>","PeriodicalId":11559,"journal":{"name":"EJNMMI Physics","volume":" ","pages":""},"PeriodicalIF":3.5,"publicationDate":"2026-06-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13454082/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148149113","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Quantitative accuracy of ¹⁷⁷Lu SPECT/CT imaging using ring-shaped CZT versus dual-head NaI systems.","authors":"Rachele Danieli, Clémentine Marin, Anna-Lena Theisen, Johannes Tran-Gia, Carlos Artigas, Bruno Vanderlinden, Nick Reynaert, Patrick Flamen, Hugo Levillain","doi":"10.1186/s40658-026-00892-2","DOIUrl":"10.1186/s40658-026-00892-2","url":null,"abstract":"<p><strong>Background: </strong>Ring-shaped systems based on CZT are promising for quantitative imaging, but their accuracy may be affected by septal penetration of high-energy photons-given the fixed collimator-and by limitations in scatter correction due to low-energy tailing. This study compares the quantitative performance of a ring-shaped CZT system with that of a conventional dual-head NaI SPECT/CT system (StarGuide™ and NM/CT 870 DR, both GE HealthCare) using the 208 keV photopeak of ¹⁷⁷Lu.</p><p><strong>Methods: </strong>A NEMA phantom with 3D-printed anthropomorphic inserts, including kidneys and lumbar vertebrae, as well as standard spherical inserts, was filled with activity concentrations mimicking the distribution observed in patients 1 day post-injection of 7.4 GBq of [¹⁷⁷Lu]Lu-PSMA-I&T. The phantom was scanned repeatedly on both systems (scan duration/bed position: 7 min for StarGuide™ and 20 min for NM/CT 870 DR). Quantitative accuracy and reproducibility were evaluated using the mean error and the coefficient of variation (CV) over repeated measurements, respectively. Additionally, a group of patients treated with [¹⁷⁷Lu]Lu-PSMA-I&T underwent sequential SPECT/CT on both systems to confirm the phantom-based results.</p><p><strong>Results: </strong>The total activity measured within the phantom deviated from the expected value by means of 13% for the StarGuide™ and 0% for the NM/CT 870 DR. After partial-volume-effect correction based on recovery coefficients, the activity concentration in kidney inserts was measured with ~ 5% accuracy on both systems. For the StarGuide™, mean errors in tumour inserts (volumes: 2.6-28 ml) ranged from - 8% to 3%, whereas a consistent underestimation by an average of - 11% was observed for the NM/CT 870 DR. The StarGuide™ significantly overestimated the background activity concentration (59%), while the NM/CT 870 DR showed a smaller error (- 8%). Reproducibility was lower for the StarGuide™, with maximum CV values of 7%, compared with 3% for the NM/CT 870 DR. Clinical findings were consistent with phantom results.</p><p><strong>Conclusions: </strong>The StarGuide™ provided slightly more accurate activity quantification in regions of high relative uptake, such as tumours and kidneys, compared with the NM/CT 870 DR. However, quantification in regions of low relative uptake and total activity estimation were less accurate, likely due to septal penetration. The lower reproducibility suggests that longer scan durations may be considered.</p>","PeriodicalId":11559,"journal":{"name":"EJNMMI Physics","volume":" ","pages":""},"PeriodicalIF":3.5,"publicationDate":"2026-06-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13493729/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148149134","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Optimization of brain PET markerless head motion correction in a large human cohort.","authors":"Tianyi Zeng, Jiazhen Zhang, Jean-Dominique Gallezot, Kathryn Fontaine, Weize Jiang, Paul Gravel, Tim Mulnix, Mika Naganawa, Zhaohui Yang, Xinyue Zhang, Su Wang, Xishan Sun, Lingzhi Hu, Richard E Carson","doi":"10.1186/s40658-026-00885-1","DOIUrl":"10.1186/s40658-026-00885-1","url":null,"abstract":"<p><strong>Purpose: </strong>Uncorrected head motion in brain PET degrades image resolution and biases quantification. Previously, we evaluated the United Imaging Healthcare markerless motion tracking (UMT) system for brain PET (Baseline UMT). This study provides an expanded validation in a large cohort compared to the Vicra with improved methodology (Optimized UMT).</p><p><strong>Methods: </strong>We developed automatic processing to define the upper face region and added a 2-step Iterative Closest Points registration to reduce non-rigid motion effects. Optimized and Baseline UMT were first compared with simulations using measured motion and intentional facial expressions. In the human study, we evaluated 51 dynamic human studies (Siemens mCT) using 5 radiopharmaceuticals. Vicra data were used as the gold standard, after assessment of motion data quality using motion-corrected centroid-of-distribution. Comparisons between Optimized UMT, no motion correction (NMC), Post-Reconstruction Registration (PRR), and Baseline UMT were performed. Static and dynamic analyses assessed the differences of region-of-interest standardized uptake values (SUV) compared to Vicra. Time activity curve (TAC) analysis was performed to quantify uncorrected motion from the residual standard deviation (SD) around fitted TACs.</p><p><strong>Results: </strong>In simulation studies, optimized UMT reduced error by 20% relative to NMC and by 9% relative to Baseline UMT under intentional facial expressions, reflecting the impact of the updated UMT registration. In the human static analysis of SUV, optimized UMT outperformed PRR (+ 1.6%) and NMC (+ 6.5%) on average grey matter difference. Similar results were found in the dynamic analysis. In the TAC analysis, optimized UMT consistently yielded lower residual variability than NMC and PRR across tracers and ROIs, with a narrower range of median %SD values (0.3-1.8%) compared with NMC (1.6-6.5%) and PRR (0.5-1.9%), while demonstrating performance comparable to the reference Vicra-based correction.</p><p><strong>Conclusion: </strong>Optimized UMT achieved comparable performance to Vicra and significantly improved quantification over PRR.</p>","PeriodicalId":11559,"journal":{"name":"EJNMMI Physics","volume":" ","pages":""},"PeriodicalIF":3.5,"publicationDate":"2026-05-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13433684/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148053352","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}