EJNMMI Physics最新文献

{"title":"On the reduction of imaging time-points for dosimetry in radionuclide therapy.","authors":"Johan Gustafsson, Jan Taprogge","doi":"10.1186/s40658-025-00721-y","DOIUrl":"10.1186/s40658-025-00721-y","url":null,"abstract":"<p><strong>Background: </strong>The aim was to develop a theoretical framework for how errors in estimated activities propagate to a dispersion in time-integrated activity in radionuclide-therapy dosimetry and how this affects the comparison of radionuclide-therapy dosimetry schemes.</p><p><strong>Methods: </strong>Formulae for the variance of relative errors of estimated time-integrated activities and relative differences in time-integrated activities between measurement schemes when one or more time-points are removed were derived using the law of propagation of uncertainty for a population of time-activity-curve parameters. The formulae were derived under the assumptions of fixed coefficients of variation for estimated activities, and underlying mono-exponential curves. Analytical predictions were compared with results from numerical simulations and data for kidneys, liver, and spleen from a data-set of 18 patients treated with ¹⁷⁷Lu-DOTA-TATE.</p><p><strong>Results: </strong>The dispersion in time-integrated activity is minimized if the time-points used for curve fitting have a large dispersion and are centered over the mean of <math><mrow><mi>τ</mi> <mo>=</mo> <msubsup><mi>λ</mi> <mrow><mtext>eff</mtext></mrow> <mrow><mo>-</mo> <mn>1</mn></mrow> </msubsup> </mrow> </math> over the population, where <math><msub><mi>λ</mi> <mtext>eff</mtext></msub> </math> is the effective decay constant (i.e., the sum of the biological and physical decay constants). For large dispersions of decay constants in the population, the centering of time-points becomes gradually less important. The analytical expressions replicated the main trends from the numerical simulations. Furthermore, the analytical expressions predicted correctly the optimal reduced imaging schedule in 9 of 12 pairwise comparisons between schedules for patients.</p><p><strong>Conclusions: </strong>The dispersion of errors and deviations in estimated time-activity curves can be predicted using simple formulae. These formulae have the potential to be used for optimization of dosimetry measurement schemes for established and new radiopharmaceuticals as long as the mean and dispersion of biological half-lives are known in the patient population.</p>","PeriodicalId":11559,"journal":{"name":"EJNMMI Physics","volume":"12 1","pages":"14"},"PeriodicalIF":3.0,"publicationDate":"2025-02-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11799503/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143255130","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":"Low-activity [¹⁸F]-somatostatin receptor (SSTR) imaging using [¹⁸F]SiTATE on a long axial field-of-view PET/CT scanner.","authors":"Nils F Trautwein, Eduardo Calderón, Pia M Linder, Gerald Reischl, Philippe Driessen, Wenhong Lan, Andreas S Brendlin, Thorben Groß, Helmut Dittmann, Martina Hinterleitner, Christian la Fougère, Fabian P Schmidt, Lena S Kiefer","doi":"10.1186/s40658-025-00720-z","DOIUrl":"10.1186/s40658-025-00720-z","url":null,"abstract":"<p><strong>Purpose: </strong>¹⁸F-labelled somatostatin receptor tracers have recently gained popularity due to their better spatial resolution, longer half-life and lower costs compared to ⁶⁸Ga-labeled tracers. The aim of this study was to evaluate the impact and limitations of reduced administered activities of [¹⁸F]SiTATE on image quality, lesion detectability and quantitative PET parameters in a long axial field-of-view (LAFOV) PET/CT scanner.</p><p><strong>Methods: </strong>Twenty-four patients with histologically confirmed neuroendocrine tumor, who underwent clinically indicated [¹⁸F]SiTATE PET/CT examination (3.0 MBq/kg, 5 min PET scan time) on a Siemens Biograph Vision Quadra LAFOV PET/CT, were included retrospectively in this study. PET list-mode data were rebinned for shorter frame durations to simulate 5 min scans with lower activities of injected radiotracer. A comparison of image reconstruction in high sensitivity (HS) and ultra-high sensitivity mode (UHS) mode was performed. Subjective image quality, noise and lesion detectability of n = 122 lesions were rated using a 5-point Likert scale. The molecular tumor volume (MTV), signal-to-noise ratio (SNR), tumor-to-liver activity concentration ratio (TLR) and standardized uptake values (SUV) were analyzed.</p><p><strong>Results: </strong>Subjective image quality decreased with simulated reduction of injected activity with generally superior ratings in the UHS mode compared to the HS mode. Despite a reduction to 1 MBq/kg of [¹⁸F]SiTATE all lesions were still detected while at 0.25 MBq/kg lesion detectability decreased to 70% (HS) and 93% (UHS). Only minor changes in SUV_mean and TLR were detected with reduced activity. However, reduced activities led to an increase in SUV_SD, which in turn caused a decrease in SNR (at 1 MBq/kg: 7.3 in HS and 9.0 in UHS mode and an increase in deviation of the MTV.</p><p><strong>Conclusion: </strong>Reducing the administered activity of injected [¹⁸F]SiTATE by 66% to 1 MBq/kg (HS & UHS) is feasible in a LAFOV PET/CT scanner, maintaining clinically diagnostic image quality without statistically significant deviations in PET uptake parameters and MTV. Furthermore, in low activity [¹⁸F]SiTATE PET/CT, the UHS mode improves image quality and noise as well as lesion detectability compared to HS mode, further reinforcing the clinical benefits of this recently introduced reconstruction mode.</p>","PeriodicalId":11559,"journal":{"name":"EJNMMI Physics","volume":"12 1","pages":"13"},"PeriodicalIF":3.0,"publicationDate":"2025-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11799470/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143188426","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":"Discordance between ⁹⁰Y-PET/CT(MR)-estimated activity and dose calibrator measured administered activity: an international study in SIRT patients treated with resin and glass microspheres.","authors":"Thomas Carlier, Silvano Gnesin, Justin K Mikell, Maurizio Conti, John O Prior, Niklaus Schaefer, Maria Del Sol Pérez Lago, Clément Bailly, Yuni K Dewaraja, Thiago V M Lima","doi":"10.1186/s40658-025-00725-8","DOIUrl":"10.1186/s40658-025-00725-8","url":null,"abstract":"<p><strong>Purpose: </strong>Therapeutic administration of ⁹⁰Y-loaded microspheres is routinely used for primary and secondary liver tumours. For activity-based therapeutic prescription the activity must be within 10% of the intended activity. Previous studies reported significant discrepancies between manufacturer-declared vial activities and both experimental and Monte-Carlo assessments, greater than 10%, for resin/glass ⁹⁰Y-microspheres. The objective of this work was to investigate whether these discrepancies were also seen in patients.</p><p><strong>Methods: </strong>We analysed patient ⁹⁰Y-PET reconstructions (99 glass and 15 resin microspheres) from 4 different institutions and 4 different systems. We considered tail-fitting background scaling (TFBS) and absolute scaling (ABS), for scatter correction. Residuals after therapeutic injection were measured. Eighty-one patients were imaged with PET/CT and 33 with PET/MR. The PET measured activity (A_PET) was assessed in the whole liver. The ratio A_PET/A_calibrator was calculated for each patient, where A_calibrator was the injected activity measured by the dose calibrator corrected for residual and lung shunt.</p><p><strong>Results: </strong>Quantification ratio between calibrators and PET was significantly different from 1, regardless of the scatter correction used. In glass microspheres, the mean A_PET/CT/A_calibrator was 0.84 ± 0.06 for TFBS and 0.90 ± 0.06 for ABS (0.66 ± 0.09 and 0.76 ± 0.07 for (A_PET/MR/A_calibrator)). The mean A_PET/CT/A_calibrator ratio for resin microspheres was 1.16 ± 0.09 for TFBS and 1.30 ± 0.12 for ABS.</p><p><strong>Conclusions: </strong>We observed in patients similar activity discrepancies as reported for vials, with a relative difference of 44 ± 16% between glass and resin ⁹⁰Y-loaded microspheres. In ⁹⁰Y hepatic radioembolization, the 10% accuracy prerequisite on knowing the administered therapeutic activity is then unlikely to be met.</p>","PeriodicalId":11559,"journal":{"name":"EJNMMI Physics","volume":"12 1","pages":"12"},"PeriodicalIF":3.0,"publicationDate":"2025-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11799454/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143188421","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":"Validation of a data-driven motion-compensated PET brain image reconstruction algorithm in clinical patients using four radiotracers.","authors":"Ole L Munk, Anders B Rodell, Patricia B Danielsen, Josefine R Madsen, Mie T Sørensen, Niels Okkels, Jacob Horsager, Katrine B Andersen, Per Borghammer, Joel Aanerud, Judson Jones, Inki Hong, Sven Zuehlsdorff","doi":"10.1186/s40658-025-00723-w","DOIUrl":"10.1186/s40658-025-00723-w","url":null,"abstract":"<p><strong>Purpose: </strong>Patients with dementia symptoms often struggle to limit movements during PET examinations, necessitating motion compensation in brain PET imaging to ensure the high image quality needed for diagnostic accuracy. This study validates a data-driven motion-compensated (MoCo) PET brain image reconstruction algorithm that corrects head motion by integrating the detected motion frames and their associated rigid body transformations into the iterative image reconstruction. Validation was conducted using phantom scans, healthy volunteers, and clinical patients using four radiotracers with distinct tracer activity distributions.</p><p><strong>Methods: </strong>We conducted technical validation experiments of the algorithm using Hoffman brain phantom scans during a series of controlled movements, followed by two blinded reader studies assessing image quality between standard images and MoCo images in 38 clinical patients receiving dementia scans with [¹⁸F]Fluorodeoxyglucose, [¹⁸F]N-(3-iodopro-2E-enyl)-2beta-carbomethoxy-3beta-(4'-methylphenyl)-nortropane, [¹⁸F]flutemetamol, and a research group comprising 25 elderly subjects scanned with [¹⁸F]fluoroethoxybenzovesamicol.</p><p><strong>Results: </strong>The Hoffman brain phantom study demonstrated the algorithm's capability to detect and correct for even minimal movements, 1-mm translations and 1⁰ rotations, applied to the phantom. Within the clinical cohort, where standard images were deemed suboptimal or non-diagnostic, all MoCo images were classified as having acceptable diagnostic quality. In the research cohort, MoCo images consistently matched or surpassed the standard image quality even in cases with minimal head movement, and the MoCo algorithm never led to degraded image quality.</p><p><strong>Conclusion: </strong>The PET brain MoCo reconstruction algorithm was robust and worked well for four different tracers with markedly different uptake patterns. Moco images markedly improved the image quality for patients who were unable to lie still during a PET examination and obviated the need for any repeat scans. Thus, the method was clinically feasible and has the potential for improving diagnostic accuracy.</p>","PeriodicalId":11559,"journal":{"name":"EJNMMI Physics","volume":"12 1","pages":"11"},"PeriodicalIF":3.0,"publicationDate":"2025-02-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11790531/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143079168","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":"Phantom-based investigation of block sequential regularised expectation maximisation (BSREM) reconstruction for zirconium-89 PET-CT for varied count levels.","authors":"Lara M Bonney, Matthew D Walker, Daniel R McGowan","doi":"10.1186/s40658-025-00722-x","DOIUrl":"10.1186/s40658-025-00722-x","url":null,"abstract":"<p><strong>Background: </strong>Zirconium-89 (Zr-89) PET tracers have become increasingly significant in the field of nuclear medicine due to their 3-day physical half-life, allowing for the study of dynamic biological processes over relatively long timeframes. To date there has been limited publication of studies focused on optimisation of acquisition parameters for Zr-89 PET. This paper outlines a short phantom study investigating the optimal beta regularization parameter for quantitation and noise in block sequential regularised expectation maximisation (BSREM) also known as Bayesian penalized likelihood (BPL) reconstruction, for varying image noise characteristics (acquisition duration).</p><p><strong>Results: </strong>The choice of the beta regularisation parameter substantially impacts image quality and quantitation. For larger volumes, BSREM reconstruction enhanced image quality (lower noise) and maintained quantitation, whereas for smaller volumes quantitation worsened as compared to OSEM for high regularisation parameters.</p><p><strong>Conclusion: </strong>Where BSREM reconstruction is used for Zr-89 images, careful attention must be paid to the choice of weighting factor, especially for quantitative clinical studies. The effect of varying beta on several measures of image quality was characterised for the case of a phantom, with the results indicating that the value of beta for optimal Zr-89 quantitation is lower than what is generally used for optimal visualisation. This work demonstrates the need for careful attention to the reconstruction methods used for quantitative imaging studies, such as those required for theragnostic imaging.</p>","PeriodicalId":11559,"journal":{"name":"EJNMMI Physics","volume":"12 1","pages":"10"},"PeriodicalIF":3.0,"publicationDate":"2025-02-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11790545/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143079167","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 review of state-of-the-art resolution improvement techniques in SPECT imaging.","authors":"Zhibiao Cheng, Ping Chen, Jianhua Yan","doi":"10.1186/s40658-025-00724-9","DOIUrl":"10.1186/s40658-025-00724-9","url":null,"abstract":"<p><p>Single photon emission computed tomography (SPECT), a technique capable of capturing functional and molecular information, has been widely adopted in theranostics applications across various fields, including cardiology, neurology, and oncology. The spatial resolution of SPECT imaging is relatively poor, which poses a significant limitation, especially the visualization of small lesions. The main factors affecting the limited spatial resolution of SPECT include projection sampling techniques, hardware and software. Both hardware and software innovations have contributed substantially to improved SPECT imaging quality. The present review provides an overview of state-of-the-art methods for improving spatial resolution in clinical and pre-clinical SPECT systems. It delves into advancements in detector design and modifications, projection sampling techniques, traditional reconstruction algorithm development and optimization, and the emerging role of deep learning. Hardware enhancements can result in SPECT systems that are both lighter and more compact, while also improving spatial resolution. Software innovations can mitigate the costs of hardware modifications. This survey offers a thorough overview of the rapid advancements in resolution enhancement techniques within the field of SPECT, with the objective of identifying the most recent trends. This is anticipated to facilitate further optimization and improvement of clinical systems, enabling the visualization of small lesions in the early stages of tumor detection, thereby enhancing accurate localization and facilitating both diagnostic imaging and radionuclide therapy, ultimately benefiting both clinicians and patients.</p>","PeriodicalId":11559,"journal":{"name":"EJNMMI Physics","volume":"12 1","pages":"9"},"PeriodicalIF":3.0,"publicationDate":"2025-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11782768/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143064494","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":"Count-rate management in ¹³¹I SPECT/CT calibration.","authors":"Staffan Jacobsson Svärd, Cecilia Hindorf, Joachim N Nilsson","doi":"10.1186/s40658-025-00718-7","DOIUrl":"10.1186/s40658-025-00718-7","url":null,"abstract":"<p><strong>Background: </strong>System calibration is essential for accurate SPECT/CT dosimetry. However, count losses due to dead time and pulse pileup may cause calibration errors, in particular for ¹³¹I, where high count rates may be encountered. Calibration at low count rates should also be avoided to minimise detrimental effects from e.g. background counts and statistical fluctuations. This paper aims to present experimental data illustrating count-rate dependencies and to propose practical routines to mitigate errors in the ¹³¹I calibration procedure without needing advanced analysis tools.</p><p><strong>Results: </strong>The sensitivities of two General Electric (GE) Discovery 670 Pro systems were assessed using two Jaszczak phantom geometries. SPECT/CT data were collected over two months, starting with an initial ¹³¹I content of > 2 GBq, decaying to approximately 20 MBq. This allowed for a detailed analysis of count losses due to dead time and pulse pileup. From the sensitivity analysis, it was shown that robust calibration was obtained for ¹³¹I phantom activities ranging between 250 and 1500 MBq.</p><p><strong>Conclusions: </strong>The results show that adequate corrections for dead-time and pulse-pileup counting losses are essential for accurate calibration. It is argued that loss corrections should be based on total spectrum count rates in projections and not only on the 364.5 keV energy window data. The measurement campaigns presented in this paper, using basic tools and equipment, may serve as a model for establishing routines for count-loss corrections as well as for system calibration and regular control of system sensitivity. The data suggest that analysis of source and count concentration in a homogeneous Jaszczak phantom offers robust calibration, whereas analysis of source strength and counts in a delineated phantom insert offers a practical and robust method for regular quality control.</p>","PeriodicalId":11559,"journal":{"name":"EJNMMI Physics","volume":"12 1","pages":"8"},"PeriodicalIF":3.0,"publicationDate":"2025-01-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11769881/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143037613","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":"Exhalation of Rn-219 by patients treated with Radium-223.","authors":"Carsten Wanke, Joerg Pinkert, Lilli Geworski, Bastian Szermerski","doi":"10.1186/s40658-025-00719-6","DOIUrl":"10.1186/s40658-025-00719-6","url":null,"abstract":"<p><strong>Background: </strong>Treatment with Ra-223 dichloride is approved for the therapy of castration resistant prostate cancer (CRPC) with symptomatic bone metastases and no known visceral metastases in Europe since 2013, and Ra-223 is under discussion for labelling other molecules and nanoparticles. The direct progeny of Ra-223 is Rn-219, also known as actinon, a radioactive noble gas with a half-life of 3.98 s. This Rn-219 can be exhaled by patients while Ra-223 is present in the blood. Hence, direct measurements for assessing the exhalation of Rn-219 were performed for the first time in the context of the non-interventional multicenter study \"RAPSODY\", a substudy to the international early access program, which aimed at assessing the radiation exposure of relatives of patients suffering from castration resistant prostate cancer with bone metastases and treated with Ra-223 dichloride in an outpatient setting, in order to investigate if this kind of method is functional and tolerated by the patients.</p><p><strong>Methods: </strong>Rn-219 was measured directly in patients' exhalations using Alphaguard radon monitors (Saphymo, formerly Genitron, Frankfurt, Germany), originally intended for the measurement of Rn-222, and custom-made breath-test kits. Measurements were performed 20-30 min p. i. and 3-4 h p. i. In total, datasets from 21 administrations in 14 patients were obtained.</p><p><strong>Results: </strong>Although 75% of the measurement data 20-30 min p. i. and 35% of the measurement data 3-4 h p. i., respectively, were censored due to exceedance of the upper limit of the Alphaguards' measurement range in the applied measurement setup, statistical data were derived based on the assumption of lognormal distributions. For measurements 3-4 h p. i., mean activity concentrations of Rn-219 in exhaled breath of approx. 4.4 kBq/l were obtained. In measurements 20-30 min p. i., the expectation value of the activity concentration of approx. 6 kBq/l, derived by statistical methods, was higher.</p><p><strong>Conclusions: </strong>Direct measurements using Alphaguard instruments are suitable for assessing the exhalation of Rn-219 by patients treated with Ra-223. The measurement method is well tolerated by the patients. Rn-219 is present in patients' exhalations. Our results are in accordance with published data obtained using other, indirect measurement methods.</p>","PeriodicalId":11559,"journal":{"name":"EJNMMI Physics","volume":"12 1","pages":"6"},"PeriodicalIF":3.0,"publicationDate":"2025-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11757652/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143022769","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":"Correction: Radiopharmacokinetic modelling and radiation dose assessment of ²²³Ra used for treatment of metastatic castration-resistant prostate cancer.","authors":"Vera Höllriegl, Nina Petoussi-Henss, Kerstin Hürkamp, Juan Camilo Ocampo Ramos, Wei Bo Li","doi":"10.1186/s40658-024-00708-1","DOIUrl":"10.1186/s40658-024-00708-1","url":null,"abstract":"","PeriodicalId":11559,"journal":{"name":"EJNMMI Physics","volume":"12 1","pages":"7"},"PeriodicalIF":3.0,"publicationDate":"2025-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11757809/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143022760","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 preclinical in ovo PET/MRI: influence of attenuation and quantification methods.","authors":"Theresa Balber, Katarína Benčurová, Manuela Mayrhofer, Joachim Friske, Martin Haas, Claudia Kuntner, Thomas H Helbich, Marcus Hacker, Markus Mitterhauser, Ivo Rausch","doi":"10.1186/s40658-024-00714-3","DOIUrl":"10.1186/s40658-024-00714-3","url":null,"abstract":"<p><strong>Aim: </strong>The combination of positron emission tomography (PET) and magnetic resonance imaging (MRI) provides an innovation leap in the use of fertilized chicken eggs (in ovo model) in preclinical imaging as PET/MRI enables the investigation of the chick embryonal organ-specific distribution of PET-tracers. However, hybrid PET/MRI inheres technical challenges in quantitative in ovo PET such as attenuation correction (AC) for the object as well as for additional hardware parts present in the PET field-of-view, which potentially contribute to quantification biases in the PET images if not accounted for. This study aimed to investigate the influence of the different sources of attenuation on in ovo PET/MRI and assess the accuracy of MR-based AC for in ovo experiments.</p><p><strong>Method: </strong>An in-house made chicken egg phantom was used to investigate the magnitude of self-attenuation and the influence of the MRI hardware on the PET signal. The phantom was placed in a preclinical PET/MRI system and PET acquisitions were performed without, and after subsequently adding the different hardware parts to the setup. Reconstructions were performed without any AC for the different setups and with subsequently incorporating the hardware parts into the AC. In addition, in ovo imaging was performed using [¹⁸F]FDG and [⁶⁸Ga]Ga-Pentixafor, and PET data was reconstructed with the different AC combinations. Quantitative accuracy was assessed for the phantom and the in ovo measurements.</p><p><strong>Results: </strong>In general, not accounting for the self-attenuation of the egg and the hardware parts caused an underestimation of the PET signal of around 49% within the egg. Accounting for all sources of attenuation allowed a proper quantification with global offsets of 2% from the true activity. Quantification based on % injected dose per cc (%ID/cc) was similar for the in ovo measurements, regardless of whether hardware parts were included in AC or not, when the injected activity was extracted from the PET images. However, substantial quantification biases were found when the self-attenuation of the egg was not taken into account.</p><p><strong>Conclusion: </strong>Self-attenuation of the egg and PET signal attenuation within the hardware parts of the MRI substantially influence quantitative accuracy in in ovo measurements. However, when compensating for the self-attenuation of the egg by a respective AC, a reliable quantification using %ID/cc can be performed even if not accounting for the attenuation of the hardware parts.</p>","PeriodicalId":11559,"journal":{"name":"EJNMMI Physics","volume":"12 1","pages":"5"},"PeriodicalIF":3.0,"publicationDate":"2025-01-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11753441/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143002281","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}