EJNMMI Physics最新文献

{"title":"Design and first experimental results of an edgeless PET prototype for breast imaging: DeepBreast.","authors":"Marta Freire, Santiago Jiménez-Serrano, Andrea Gonzalez-Montoro, Francisco B García, José F Toledo, Julio Barberá, Jorge Álamo, Irene Torres-Espallardo, Luis F Vidal, Francis Loignon-Houle, Carlos de Alfonso, Sara Echegoyen, María J Rodríguez-Álvarez, Filomeno Sánchez, Antonio J González","doi":"10.1186/s40658-026-00869-1","DOIUrl":"10.1186/s40658-026-00869-1","url":null,"abstract":"<p><strong>Background: </strong>Breast cancer causes the largest number of cancer-related deaths among women worldwide. With the aim of improving Positron Emission Tomography (PET) technology for accurate breast cancer diagnosis and staging, we propose a system design based on monolithic crystals with inherent Depth of Interaction (DOI) capabilities and an innovative edgeless detector ring. This approach eliminates the physical gaps between PET detectors, improving the system detection efficiency while potentially enhancing the image quality since edge effects are reduced. We have developed a dedicated breast PET system prototype (DeepBreast) to show the feasibility of this design. The system is composed of 14 curved LYSO monolithic scintillators of 12.5 mm thickness glued side-by-side with a high-refractive index compound. The useful transaxial and axial Field of View (FOV) of the system are 160 mm and 50 mm, respectively. A Neural Network technique was used for the x- and y- photon impact position estimation. The impact DOI and energy values were determined using the Voronoi calibration methodology. An initial experimental evaluation of the DeepBreast system has been performed inspired by the NEMA protocols for whole-body and small-animals PET scanners.</p><p><strong>Results: </strong>A nearly flat spatial resolution as a function of radial position was obtained, which indicates the DOI capability of the system to mitigate parallax errors. An average spatial resolution of 1.9 ± 0.1 mm, 1.9 ± 0.1 mm and 1.7 ± 0.1 mm FWHM was achieved at the center of the axial FOV for the radial, tangential, and axial directions, respectively. A maximum sensitivity value of 2% was measured at the center of the FOV. The noise equivalent count rate peak reached 15 kcps at 13.4 MBq. Moreover, percent contrast values of 27.9%, 28.8%, 56.8%, 72.5%, 87.2% and 84.2% were achieved for 4.5 mm, 6 mm, 9 mm, 12 mm, 15 mm and 20 mm cylinders of a larger dedicated IQ phantom, respectively.</p><p><strong>Conclusions: </strong>The initial experimental results demonstrate the feasibility of the DeepBreast as an innovative PET scanner for breast cancer imaging.</p>","PeriodicalId":11559,"journal":{"name":"EJNMMI Physics","volume":" ","pages":""},"PeriodicalIF":3.5,"publicationDate":"2026-04-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13212846/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147697844","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":"Gravity versus pump-driven infusion in targeted radionuclide therapy: a model-based dosimetric evaluation of extravasation.","authors":"Olivia Lienhardt, Oreste Allegrini, Nathan Poterszman, Florian Ritzenthaler, Clémence Porot, Christophe Mazzara, Francois Somme, Julien Salvadori","doi":"10.1186/s40658-026-00852-w","DOIUrl":"10.1186/s40658-026-00852-w","url":null,"abstract":"<p><strong>Background: </strong>Intravenous administration of [Formula: see text]Lu-labeled radiopharmaceuticals (RPMs) such as PSMA and DOTATATE entails a risk of extravasation, potentially resulting in absorbed doses exceeding thresholds for deterministic tissue damage. Gravity-driven and pump-assisted infusion methods differ in dilution and flow dynamics, which directly affect the extravasated dose. This study aimed to extend and validate an analytical model for quantitative comparison of extravasation-related dosimetric risks between both strategies and to inform clinical protocol optimization.</p><p><strong>Methods: </strong>A previously published analytical model for gravity-driven delivery was extended to pump-assisted infusion by incorporating method-specific dilution kinetics within the mixing compartment and laminar (Poiseuille) flow through the infusion line and venous system. Extravasation was modeled mechanistically to estimate extravasated activity, concentration, and equivalent dose rate (EDR) at the injection site. Model validation was performed by comparing simulated EDRs with in vivo measurements from 28 clinical [Formula: see text]Lu-PSMA infusions using the ED3 bilateral dosimetry system. Simulations covered clinically relevant parameter ranges, and absorbed doses were derived by combining simulated concentrations with Monte Carlo-based S-values, assuming an effective residence time of 1.5 h supported by clinical SPECT/CT data.</p><p><strong>Results: </strong>The model reproduced measured EDR kinetics with a mean deviation of 16 % during infusion. Gravity-driven infusions generated steep concentration peaks in case of early extravasation, with absorbed dose strongly dependent on onset timing. Pump-assisted delivery yielded stable profiles largely independent of onset. Across clinical parameter ranges, gravity-based protocols produced extravasated concentrations of 155-345 [Formula: see text] and doses of 30-68 Gy, with mitigation relying on vial pre-dilution at the cost of prolonged infusion times. Pump-assisted protocols allowed safer modulation (21-180 [Formula: see text], 4-35 Gy) through independent control of RPM and saline flow rates, without vial dilution. For equivalent infusion durations (e.g., 44 min), pump delivery achieved extravasated doses and concentrations about sevenfold lower than gravity (5.2 vs. 35 Gy), supporting its clinical value for protocol optimization and radioprotection.</p><p><strong>Conclusion: </strong>We present an analytical model for estimating absorbed dose in the event of extravasation during [Formula: see text]Lu-RPM infusion. The results highlight the decisive safety benefits of pump-assisted administration over gravity-driven delivery and support its implementation as a proactive strategy to minimize extravasation risk, improve patient safety, and harmonize therapeutic protocols across centres .</p>","PeriodicalId":11559,"journal":{"name":"EJNMMI Physics","volume":" ","pages":""},"PeriodicalIF":3.5,"publicationDate":"2026-04-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13212839/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147697841","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":"Multi-site distributed training with data protections for PET-based synthetic CT.","authors":"Kasper Jørgensen, Lauren Partin, Raghavan Ashok, Vijay Shah, Anders Bertil Rodell, Martin Bazik, Bruce Spottiswoode, Flemming Littrup Andersen","doi":"10.1186/s40658-026-00868-2","DOIUrl":"10.1186/s40658-026-00868-2","url":null,"abstract":"<p><p>BACKGROUND: Accurate PET quantification relies on attenuation correction (AC), commonly performed using a linear attenuation map derived from a CT acquisition. However, CT can introduce misregistration artifacts and adds radiation dose. Synthetic CT (sCT) from non-attenuation corrected (NAC) PET offers a CT-less alternative, but training robust models requires multi-site data that may be difficult to share under privacy regulations. We aim to enable PET-based sCT training across sites without exposing data. METHODS: We built a federated learning (FL) framework and trained two sCT generators–a paired conditional GAN and a CycleGAN. Models were pretrained on a single-site cohort (Site 1, n = 425) and fine-tuned via FL using additional data from Site 1 (n = 25) and a second site with different scanners and reconstruction parameters (Site 2, n = 25). Performance was assessed on an internal hold-out set (Site 1, n = 91) and two external cohorts (Sites 3,4; n = 11, 10) using region-wise relative mean error (rME) of SUV in AC PET. RESULTS: Both models produced anatomically plausible sCT and AC PET with low errors when test data matched training distributions. FL fine-tuning improved robustness under distribution shift at Site 3, reducing errors across most regions, while maintaining comparable performance at Site 4 where protocols resembled the pretraining site. CONCLUSION: Multi-site FL is a feasible path to increase the generalizability of PET-based sCT while preserving data privacy. The proposed framework offers a practical template for training and deploying CT-less AC models across heterogeneous clinical environments. </p>","PeriodicalId":11559,"journal":{"name":"EJNMMI Physics","volume":" ","pages":""},"PeriodicalIF":3.5,"publicationDate":"2026-04-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13199553/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147688933","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 data driven motion correction for clinical brain PET/MRI radiotracers.","authors":"Martin Bolin, Anna Falk Delgado, Emilia Palmér","doi":"10.1186/s40658-026-00863-7","DOIUrl":"10.1186/s40658-026-00863-7","url":null,"abstract":"<p><strong>Purpose: </strong>The Positron Emission Tomography (PET)/Magnetic Resonance Imaging (MRI) scanner combines two diagnostic imaging modalities, providing information on anatomy and physiology. Beneficial diagnosis areas are epilepsy ([[Formula: see text]F]Fluorodeoxyglucose (FDG)) and cancer recurrence ([[Formula: see text]C]methionine (MET)), where subject motion during PET acquisition reduces image quality, potentially compromising diagnostic accuracy. This project aimed to evaluate the impact of PET data-driven motion correction (ddMC) of these clinical PET radiotracers and to assess, for the first time, whether the automatic motion categorization reflects motion levels impacting the image quality.</p><p><strong>Methods: </strong>Eighty-nine PET scans (66 [[Formula: see text]C]MET, 23 [[Formula: see text]F]FDG) were reconstructed with ddMC and without motion correction (noMC) using the research software lmDuetto toolbox (GE Healthcare, Chicago, IL, USA), and were automatically categorized into motion groups. MRI images were segmented, and the regions of interest (ROIs) transferred to the PET space. The effect of ddMC was analyzed by relative signal differences between ddMC and noMC. Motion estimation and categorization were evaluated by normalized cross correlation (XC) over time and the proposed cumulative displacement-time histogram (cDTH).</p><p><strong>Results: </strong>Overall, ddMC increased signal values within cortical ROIs compared to noMC. In the high motion category, median relative mean signal differences were 0.61% (0.41-0.80%) for [[Formula: see text]F]FDG and 0.70% (0.61-0.79%) for [[Formula: see text]C]MET. The XC improved ([[Formula: see text]F]FDG: 0.80 to 0.97, [[Formula: see text]C]MET: 0.85 to 0.98). Low and medium motion groups had lesser impact, indicating motion correction is most relevant for high motion. The XC and cDTH identified subjects whose motion classification should be revised.</p><p><strong>Conclusion: </strong>In conclusion, the results confirm previous findings with ddMC using [[Formula: see text]F]FDG and demonstrate its suitability for lower-accumulating [[Formula: see text]C]MET. The automatic motion categorization needs re-evaluation to better reflect motion affecting PET image quality.</p>","PeriodicalId":11559,"journal":{"name":"EJNMMI Physics","volume":"13 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2026-04-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13083739/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147689000","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":"Parametric analysis of dynamic long axial field-of-view ¹⁸F-FDG PET/CT studies.","authors":"Charlotte L C Smith, Gerben J C Zwezerijnen, Marijke E den Hollander, Henricus N J M Greuter, Nienke R Gerards, Josée Zijlstra, C Willemien Menke-van der Houven van Oordt, Idris Bahce, Maqsood Yaqub, Ronald Boellaard","doi":"10.1186/s40658-026-00859-3","DOIUrl":"10.1186/s40658-026-00859-3","url":null,"abstract":"<p><p>BACKGROUND: Large-axial field of view (LAFOV) PET/CT systems have improved whole-body dynamic 18F-FDG imaging, enabling improved quantitative assessment of tracer kinetics. While non-linear regression (NLR) models remain the most unbiased approach, voxel-wise implementation can suffer from convergence problems, resulting in increased uncertainties. Parametric methods such as Patlak, Generalized Patlak (gPatlak), basis function method irreversible (BFM-I), and basis function method reversible (BFM-R) offer alternatives for estimating parametric Ki and, if applicable, K1 values. This study aims to determine the most suitable parametric approach for quantifying 18F-FDG kinetics in various healthy organs and tumour lesions using a LAFOV PET/CT system. METHODS: Thirteen patients with malignancies underwent 70-minute dynamic 18F-FDG PET/CT scans on a LAFOV PET/CT system after receiving an intravenous bolus injection of 3.0 MBq/kg. First, the data were split on preference for irreversible (2T3k) or reversible (2T4k) kinetics. Ki from Patlak (t* = 30 min) and BFM-I (t* = 0 min) were compared with those derived from the 2T3k model. Ki from gPatlak (t* = 10 min) and BFM-R (t* = 0 min) were compared with those obtained with 2T4k. Ki and K1 values were extracted from the brain, liver, spleen, lung, kidney, upper leg muscle, and up to three tumour lesions per patient. RESULTS: The liver, myocardium, lungs, and muscle favoured the irreversible 2T3k model, while preferences for the kidney, brain, spleen, and tumour lesions varied across patients. For organs preferring irreversible kinetics, BFM-I (R = 0.99) outperformed Patlak (R = 0.97) in Ki agreement with the 2T3k model. For reversible kinetics, BFM-R (R = 0.95) showed better correspondence compared to gPatlak (R = 0.90) with the 2T4k model. K1 obtained by BFM-I and BFM-R also strongly correlated with those derived from compartment models. CONCLUSIONS: LAFOV PET/CT systems enable accurate whole-body kinetic modelling of 18F-FDG uptake. BFM-I and BFM-R demonstrated the highest agreement with the compartment models and are recommended when full dynamic PET scans are feasible, offering accurate Ki as well as K1 estimations across healthy organs and tumour lesions. </p>","PeriodicalId":11559,"journal":{"name":"EJNMMI Physics","volume":" ","pages":""},"PeriodicalIF":3.5,"publicationDate":"2026-04-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13187087/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147671447","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":"Contrast-enhanced CT for attenuation correction in ultra-high sensitivity long-axial field-of-view lymphoma PET: amplified quantification problems?","authors":"Jan-Luca Penner, August Blomgren, Alexander Weissensee, Michelle Amon, Shayan Acikgöz, Clemens Mingels, Justin Ferdinandus, Foroud Aghapour Zangeneh, Urban Novak, Thomas Pabst, Axel Rominger, Kuangyu Shi, Hasan Sari, Robert Seifert","doi":"10.1186/s40658-026-00866-4","DOIUrl":"10.1186/s40658-026-00866-4","url":null,"abstract":"<p><strong>Purpose: </strong>It is unclear whether the use of contrast enhanced (CE) CT for attenuation correction (AC) of [¹⁸F]FDG PET leads to higher quantification inaccuracies when used in high-sensitivity LAFOV systems. This project aimed to assess the clinical feasibility of CE-CT for AC in LAFOV-PET for lymphoma patients.</p><p><strong>Methods: </strong>Lymphoma patients who underwent LAFOV-[¹⁸F]FDG-PET for restaging with low dose AC-CT and diagnostic CE-CT were included in this retrospective analysis. PET images were reconstructed using ultra-high sensitivity (UHS) mode with CE-CT and AC-CT. Lesions and reference regions (liver and mediastinal blood pool (BP)) were evaluated.</p><p><strong>Results: </strong>SUV_max of BP and the liver increased when CE-CT was used instead of AC-CT for AC (BP: median 2.41vs.2.21, p < 0.01, 8.78% intra-patient increase; liver: 3.07vs.2.87, p < 0.01, 7.86% medina intra-patient increase). Similarly, SUV_mean was higher in CE-CT reconstructions (BP: 1.96vs.1.77, p < 0.01, 10.14% median intra-patient increase; liver: 2.50vs.2.32, p < 0.01, 7.54% median intra-patient increase). SUV_max of lesions showed a similar magnitude of increase (5.97vs.5.68, p < 0.01, 5.80% median intra-lesion increase). The SUV-ratio of the lesions to reference organs decreased when CE-CT instead of AC-CT was used for AC (BP: 2.79vs.2.99, p < 0.01, median per-lesion decrease - 4.90%; liver: 1.85vs.1.97, p < 0.01, median per-lesion decrease - 2.64%).</p><p><strong>Conclusion: </strong>The use of CE-CT for AC of LAFOV-PET in UHS mode leads to higher SUV measurements. Also, lymphoma lesions show a consistent increase in uptake. The errors in the lesions seem higher than in conventional standard axial field-of-view PETs that use CE-CT for AC. Therefore, interpretation of borderline cases warrants attention to potential errors.</p>","PeriodicalId":11559,"journal":{"name":"EJNMMI Physics","volume":" ","pages":""},"PeriodicalIF":3.5,"publicationDate":"2026-04-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13184045/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147671452","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":"Investigation of iterative deconvolution in ¹⁷⁷Lu-SPECT imaging for lesion dosimetry.","authors":"Zachary Ells, Grigory Liubchenko, Mikhail Rumiantcev, Maximilian Scheifele, Angelica Noto, Sophie C Siegmund, Sandra Resch, Andreas Harbach, Rudolf A Werner, Matthias Brendel, Gabriel Sheikh, Mathias Zacherl, Guido Böning, Lena M Unterrainer, Sibylle I Ziegler, Astrid Delker","doi":"10.1186/s40658-026-00865-5","DOIUrl":"10.1186/s40658-026-00865-5","url":null,"abstract":"<p><strong>Aim/introduction: </strong>Quantitative ¹⁷⁷Lu-SPECT allows for patient specific dosimetry, but due to the limited spatial resolution absorbed doses (AD) can be underestimated. Implementation of the Lucy-Richardson deconvolution (LRD) algorithm for spill-over correction in PET has been investigated. Therefore, the aim of this study was to extend the potential application of LRD to ¹⁷⁷Lu-SPECT based tumor dosimetry.</p><p><strong>Materials/methods: </strong>The NEMA IEC Body Phantom (foreground-to-background ratio 8:1, 237:30 kBq/mL) was measured according to the local imaging and reconstruction protocol. The two main parameters of LRD, sigma and number of iterations, were determined in two steps. First, a matched filter resolution analysis was conducted on the ground truth activity distribution as segmented from the NEMA IEC Body Phantom data to define the sigma of a 3D Gaussian point-spread-function, which describes the system's spatial resolution. Secondly, using this sigma, a suitable number of LRD iterations was determined by comparing sphere recovery coefficients (RC) and signal-to-noise ratios. The selected parameters were then applied to the reconstructed SPECT series (24, 48, and 72 h post-injection) of 20 patients who received either [¹⁷⁷Lu]Lu-DOTA-TATE (n = 10) or [¹⁷⁷Lu]Lu-PSMA-I&T (y = 10) treatment, in order to evaluate its impact on AD estimates. Lesion AD from the original reconstruction (OR) and OR + LRD were estimated using MIM SurePlan™ MRT. The AD from OR, OR + LRD, and OR + RC (phantom-based recovery correction based on volume) were compared.</p><p><strong>Results: </strong>A sigma of 6.0 mm and four iterations resulted in an average improvement of 18.9 ± 4.7% and 17.4 ± 7.6% in the sphere recovery coefficients and the signal to noise ratio, respectively. In total, 98 lesions were evaluated ([¹⁷⁷Lu]Lu-DOTA-TATE: n = 42) ([¹⁷⁷Lu]Lu-PSMA-I&T: y = 56). For OR + LRD and OR + RC an average increase of 22 ± 12% and 57 ± 36% of tumor AD was found.</p><p><strong>Conclusion: </strong>OR + LRD increased AD compared to OR, independent of administered radiopharmaceutical and lesion location. This study suggests that implementing LRD may be a promising option for image-based spill-over correction in ¹⁷⁷Lu-SPECT based dosimetry. Further studies are necessary to investigate the effect of different PVC methods, such as LRD or phantom-based correction factors, on overall uncertainty of lesion ADs.</p>","PeriodicalId":11559,"journal":{"name":"EJNMMI Physics","volume":"13 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2026-04-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13076692/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147671450","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":"Continuous bed motion versus step-and-shoot acquisition in LAFOV PET/CT: insights from multi-phantom and patient studies.","authors":"P M Linder, W Lan, E Calderón, I Rausch, C la Fougère, F P Schmidt","doi":"10.1186/s40658-026-00867-3","DOIUrl":"10.1186/s40658-026-00867-3","url":null,"abstract":"<p><strong>Background: </strong>Continuous bed motion (CBM) allows flexible extension of the scan range compared to conventional step‑and‑shoot (S&S) acquisition but has not yet been evaluated in long axial field‑of‑view (LAFOV) PET/CT. This study systematically assessed the impact of CBM on image quality, noise, and quantitative performance in the Biograph Vision Quadra LAFOV PET/CT using multi‑phantom and patient scans compared to S&S.</p><p><strong>Methods: </strong>A uniform tube phantom and a NEMA IEC phantom, positioned centrally and off-centre, were scanned across bed speeds (2.8-50 mm/s), sensitivity modes and scan ranges (106 and 150 cm) to evaluate image uniformity, axial count profiles, noise and contrast recovery coefficients (CRC). Ten oncological patients receiving [¹⁸F]PSMA-1007 or [¹⁸F]FDG underwent sequential CBM (2.8 mm/s, 378 s) and S&S (300 s) scans. Image noise, net true counts, and liver and lesion SUV values were compared using paired statistics and Bland-Altman analysis, along with PSMA expression scores.</p><p><strong>Results: </strong>For comparable count statistics and image noise, CBM required a prolonged acquisition (378 s) to match the S&S (300 s) protocol, resulting in comparable image quality for phantoms and patients. CRC and image uniformity were preserved across all evaluated conditions, even at the FOV's axial edge (50.5 cm) for 8.4 mm/s (22 mm sphere: CRC 76% S&S vs. 71% CBM). In patient scans, minor differences in axial count profiles, net true counts, and SUV values (SUV_mean bias - 0.1 (liver) and - 0.8 (lesions)) did not affect clinical scores.</p><p><strong>Conclusions: </strong>The prolonged CBM protocol provides image quality and quantitative performance comparable to S&S in LAFOV PET/CT. While the reconstructed image range remains constrained by CT coverage, the patient scan comparison with 106 cm scan range, together with extended range phantom measurements, indicate that CBM can support scan range extension beyond 106 cm without compromising diagnostic accuracy.</p>","PeriodicalId":11559,"journal":{"name":"EJNMMI Physics","volume":" ","pages":""},"PeriodicalIF":3.5,"publicationDate":"2026-04-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13076829/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147662356","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":"Fast [¹⁷⁷Lu]Lu-PSMA SPECT/CT with dual-energy acquisition and Monte Carlo-based scatter correction.","authors":"Arda Könik, Benjamin Auer, Shir Hazut Krauthammer, Praful Ravi, Thomas S C Ng, Heather A Jacene","doi":"10.1186/s40658-026-00864-6","DOIUrl":"10.1186/s40658-026-00864-6","url":null,"abstract":"<p><p>PURPOSE: Whole-body post-therapy SPECT/CT plays an important role in [177Lu]Lu-PSMA-617 (LuPSMA) radiopharmaceutical therapy for verifying biodistribution, assessing treatment response, and performing radiation dosimetry. However, conventional dual-head NaI(Tl)-based scanners typically require lengthy scans, which can be resource-intensive and challenging for patient compliance, limiting their routine use in clinical practice. This study explores reducing acquisition duration using dual-energy peaks to increase count statistics and Monte Carlo-based scatter correction (MCS) to maintain image quality and quantitative accuracy under low-count conditions. METHODS: LuPSMA scans (33 studies from 29 patients) covering mid-thigh to vertex (3 bed positions) were acquired using a dual-head NaI(Tl)-based scanner (Siemens Intevo) with both 208 and 113 keV photopeaks and corresponding scatter windows. Full-duration 12 min/bed acquisitions were reconstructed using MCS (Hermia SPECT Reconstruction, Hermes) and the scanner’s energy-window-based scatter correction (EWS), where MCS reconstruction at 12 min/bed served as the reference standard. Shorter-duration projections (1.5, 3, and 6 min/bed) were synthetically generated and reconstructed using MCS. Image quality metrics, including bias, coefficient of variation (CV), contrast ratio (CR), and signal-to-noise ratio (SNR), were evaluated across segmented organs and tumors. RESULTS: MCS reconstructions at 1.5–6 min/bed showed < 6% bias in mean organ uptake (median ~ 2%) relative to the 12 min/bed MCS (reference), significantly lower (p < 0.01) than the bias for 12 min/bed EWS (median ~ 3%). For mean tumor uptake, 3–6 min/bed MCS showed < 10% bias (median ~ 5%), with no significant difference from 12 min/bed EWS (median ~ 6%). CR remained consistent across all reconstructions (median ~ 5). MCS at 12 min/bed had slightly better CV, CR, and SNR than EWS at 12 min/bed, though differences were not statistically significant. MCS at 6 min/bed was not significantly different from either full-duration reconstruction. Visual assessments supported these findings, with MCS benefits over EWS more pronounced at lower count levels. CONCLUSION: These findings indicate that using dual-energy acquisition with MCS, scan times as short as 3–6 min/bed on conventional NaI(Tl)-based scanners maintain sufficient image quality for lesion detection, therapy monitoring, and dosimetry. These reductions in scan time could facilitate the routine implementation of post-LuPSMA SPECT/CT in clinical practice. </p>","PeriodicalId":11559,"journal":{"name":"EJNMMI Physics","volume":" ","pages":""},"PeriodicalIF":3.5,"publicationDate":"2026-04-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13199565/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147662393","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 regularization factor and attenuation correction method of Q.Clear reconstruction for brain PET/MR in epileptic patients.","authors":"Xiaolong Niu, Jieqin Lv, Hao Sun, Zhifeng Chen, Xiang Liang, Zanting Ye, Youliang Wu, Xiaojing Zhang, Lijun Lu, Pengcheng Ran","doi":"10.1186/s40658-026-00860-w","DOIUrl":"10.1186/s40658-026-00860-w","url":null,"abstract":"<p><strong>Purpose: </strong>To identify suitable regularization factor β and attenuation correction (AC) method for Q.Clear reconstruction in brain [¹⁸F]FDG PET/MR imaging of patients with epilepsy.</p><p><strong>Methods: </strong>We retrospectively collected 27 PET/MR brain images from patients with temporal lobe epilepsy. PET images were reconstructed using both ordered subset-expectation maximization and Q.Clear reconstruction (β from 50 to 600) with three AC methods: Atlas-based AC (Atlas-AC), Partial Head-based AC (PH-AC), and Zero Echo Time-based AC (ZTE-AC). Image quality was assessed using lesion-to-background (LBR) ratio, normalized standard deviation (NSD) ratio, SUV_max, and SUV_mean.</p><p><strong>Results: </strong>Q.Clear reconstruction with β values of 50 to 600 significantly increased LBR and decreased NSD compared to OSEM. β value of 300 served as a practical operating point for the three AC methods. ZTE-AC had the largest LBR and lower NSD values, PH-AC method had the lowest NSD and relatively high LBR, while Atlas-AC showed moderate performance. Comparisons of SUV_max and SUV_mean between Q.Clear (β = 300) and OSEM across all AC methods suggest that β = 300 improves lesion contrast and reduces image noise without compromising SUV value.</p><p><strong>Conclusions: </strong>Q.Clear reconstruction can improve lesion contrast and reduce noise compared to OSEM. ZTE-AC yielded the highest lesion contrast and LBR among three AC methods, PH-AC resulted in the lowest background noise, and Atlas-AC showed balanced but suboptimal performance. These findings offer practical guidance in selecting the suitable β value and AC method for optimized brain PET/MR imaging in patients with epilepsy.</p>","PeriodicalId":11559,"journal":{"name":"EJNMMI Physics","volume":" ","pages":""},"PeriodicalIF":3.5,"publicationDate":"2026-04-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13176370/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147644451","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}