EJNMMI Physics最新文献

{"title":"Accuracy of holmium-166 SPECT/CT quantification over a large range of activities.","authors":"Lovisa E L Westlund Gotby, Daphne Lobeek, Joey Roosen, Maarten de Bakker, Mark W Konijnenberg, J Frank W Nijsen","doi":"10.1186/s40658-024-00683-7","DOIUrl":"https://doi.org/10.1186/s40658-024-00683-7","url":null,"abstract":"<p><strong>Background: </strong>Quantitative imaging is a crucial step for dosimetry in radionuclide therapies. Traditionally, SPECT/CT imaging is quantified based on scanner-specific conversion factors or self-calibration, but recently absolute quantification methods have been introduced in commercial SPECT reconstruction software (Broad Quantification, Siemens Healthineers). In this phantom study we investigate the accuracy of three quantification methods for holmium-166 SPECT/CT imaging, and provide recommendations for clinical dosimetry.</p><p><strong>Methods: </strong>One cylindrical phantom, filled with a homogeneous holmium-166-chloride activity concentration solution, was imaged at one time point to determine a scanner-specific conversion factor, and to characterize the spatial dependency of the activity concentration recovery. One Jaszczak phantom with six fillable spheres, 10:1 sphere-to-background ratio, was imaged over a large range of holmium-166 activities (61-3130 MBq). The images were reconstructed with either an ordered subset expectation maximization (OSEM, Flash3D-reconstruction; scanner-specific quantification or self-calibration quantification) or an ordered subset conjugate gradient (OSCG, xSPECT-reconstruction; Broad Quantification) algorithm. These three quantification methods were compared for the data of the Jaszczak phantom and evaluated based on whole phantom recovered activity, activity concentration recovery coefficients (ACRC), and recovery curves.</p><p><strong>Results: </strong>The activity recovery in the Jaszczak phantom was 28-115% for the scanner-specific, and 57-97% for the Broad Quantification quantification methods, respectively. The self-calibration-based activity recovery is inherently always 100%. The ACRC for the largest sphere (Ø60 mm, ~ 113 mL) ranged over (depending on the activity level) 0.22-0.89, 0.76-0.86, 0.39-0.72 for scanner-specific, self-calibration and Broad Quantification, respectively.</p><p><strong>Conclusion: </strong>Of the three investigated quantification methods, the self-calibration technique produces quantitative SPECT images with the highest accuracy in the investigated holmium-166 activity range.</p>","PeriodicalId":11559,"journal":{"name":"EJNMMI Physics","volume":"11 1","pages":"78"},"PeriodicalIF":3.0,"publicationDate":"2024-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11427639/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142343805","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 SPECT imaging of 155Tb and 161Tb for preclinical theranostic radiopharmaceutical development","authors":"Helena Koniar, Scott McNeil, Luke Wharton, Aidan Ingham, Michiel Van de Voorde, Maarten Ooms, Sathiya Sekar, Cristina Rodríguez-Rodríguez, Peter Kunz, Valery Radchenko, Arman Rahmim, Carlos Uribe, Hua Yang, Paul Schaffer","doi":"10.1186/s40658-024-00682-8","DOIUrl":"https://doi.org/10.1186/s40658-024-00682-8","url":null,"abstract":"Element-equivalent matched theranostic pairs facilitate quantitative in vivo imaging to establish pharmacokinetics and dosimetry estimates in the development of preclinical radiopharmaceuticals. Terbium radionuclides have significant potential as matched theranostic pairs for multipurpose applications in nuclear medicine. In particular, 155Tb (t1/2 = 5.32 d) and 161Tb (t1/2 = 6.89 d) have been proposed as a theranostic pair for their respective applications in single photon emission computed tomography (SPECT) imaging and targeted beta therapy. Our study assessed the performance of preclinical quantitative SPECT imaging with 155Tb and 161Tb. A hot rod resolution phantom with rod diameters ranging between 0.85 and 1.70 mm was filled with either 155Tb (21.8 ± 1.7 MBq/mL) or 161Tb (23.6 ± 1.9 MBq/mL) and scanned with the VECTor preclinical SPECT/CT scanner. Image performance was evaluated with two collimators: a high energy ultra high resolution (HEUHR) collimator and an extra ultra high sensitivity (UHS) collimator. SPECT images were reconstructed from photopeaks at 43.0 keV, 86.6 keV, and 105.3 keV for 155Tb and 48.9 keV and 74.6 keV for 161Tb. Quantitative SPECT images of the resolution phantoms were analyzed to report inter-rod contrast, recovery coefficients, and contrast-to-noise metrics. Quantitative SPECT images of the resolution phantom established that the HEUHR collimator resolved all rods for 155Tb and 161Tb, and the UHS collimator resolved rods ≥ 1.10 mm for 161Tb and ≥ 1.30 mm for 155Tb. The HEUHR collimator maintained better quantitative accuracy than the UHS collimator with recovery coefficients up to 92%. Contrast-to-noise metrics were also superior with the HEUHR collimator. Both 155Tb and 161Tb demonstrated potential for applications in preclinical quantitative SPECT imaging. The high-resolution collimator achieves < 0.85 mm resolution and maintains quantitative accuracy in small volumes which is advantageous for assessing sub organ activity distributions in small animals. This imaging method can provide critical quantitative information for assessing and optimizing preclinical Tb-radiopharmaceuticals.","PeriodicalId":11559,"journal":{"name":"EJNMMI Physics","volume":"27 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2024-09-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142253997","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Positronium lifetime validation measurements using a long-axial field-of-view positron emission tomography scanner.","authors":"William M Steinberger, Lorenzo Mercolli, Johannes Breuer, Hasan Sari, Szymon Parzych, Szymon Niedzwiecki, Gabriela Lapkiewicz, Pawel Moskal, Ewa Stepien, Axel Rominger, Kuangyu Shi, Maurizio Conti","doi":"10.1186/s40658-024-00678-4","DOIUrl":"https://doi.org/10.1186/s40658-024-00678-4","url":null,"abstract":"&lt;p&gt;&lt;strong&gt;Background: &lt;/strong&gt;Positron emission tomography (PET) traditionally uses coincident annihilation photons emitted from a positron interacting with an electron to localize cancer within the body. The formation of positronium (Ps), a bonded electron-positron pair, has not been utilized in clinical applications of PET due to the need to detect either the emission of a prompt gamma ray or the decay of higher-order coincident events. Assessment of the lifetime of the formed Ps, however, can potentially yield additional diagnostic information of the surrounding tissue because Ps properties vary due to void size and molecular composition. To assess the feasibility of measuring Ps lifetimes with a PET scanner, experiments were performed in a Biograph Vision Quadra (Siemens Healthineers). Quadra is a long-axial field-of-view (LA-FOV) PET scanner capable of producing list-mode data from single interaction events.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Results: &lt;/strong&gt;Ortho-Ps (o-Ps) lifetimes were measured for quartz-glass and polycarbonate samples using a &lt;math&gt; &lt;mrow&gt;&lt;mmultiscripts&gt;&lt;mrow&gt;&lt;/mrow&gt; &lt;mrow&gt;&lt;/mrow&gt; &lt;mn&gt;22&lt;/mn&gt;&lt;/mmultiscripts&gt; &lt;mtext&gt;Na&lt;/mtext&gt;&lt;/mrow&gt; &lt;/math&gt; positron source. Results produced o-Ps lifetimes of 1.538 ± 0.036 ns for the quartz glass and 1.927 ± 0.042 ns for the polycarbonate. Both o-Ps lifetimes were determined using a double-exponential fit to the time-difference distribution between the emission of a prompt gamma ray and the annihilation of the correlated positron. The measured values match within a single standard deviation of previously published results. The quartz-glass samples were additional measured with &lt;math&gt; &lt;mrow&gt;&lt;mmultiscripts&gt;&lt;mrow&gt;&lt;/mrow&gt; &lt;mrow&gt;&lt;/mrow&gt; &lt;mn&gt;82&lt;/mn&gt;&lt;/mmultiscripts&gt; &lt;mtext&gt;Rb&lt;/mtext&gt;&lt;/mrow&gt; &lt;/math&gt; , &lt;math&gt;&lt;mmultiscripts&gt;&lt;mrow&gt;&lt;/mrow&gt; &lt;mrow&gt;&lt;/mrow&gt; &lt;mn&gt;68&lt;/mn&gt;&lt;/mmultiscripts&gt; &lt;/math&gt; Ga and &lt;math&gt; &lt;mrow&gt;&lt;mmultiscripts&gt;&lt;mrow&gt;&lt;/mrow&gt; &lt;mrow&gt;&lt;/mrow&gt; &lt;mn&gt;124&lt;/mn&gt;&lt;/mmultiscripts&gt; &lt;mtext&gt;I&lt;/mtext&gt;&lt;/mrow&gt; &lt;/math&gt; to validate the lifetime using clinically available sources. A double-exponential fit was initially chosen as a similar methodology to previously published works, however, an exponentially-modified Gaussian distribution fit to each lifetime more-accurately models the data. A Bayesian method was used to estimate the variables of the fit and o-Ps lifetime results are reported using this methodology for the three clinical isotopes: 1.59 ± 0.03 ns for &lt;math&gt; &lt;mrow&gt;&lt;mmultiscripts&gt;&lt;mrow&gt;&lt;/mrow&gt; &lt;mrow&gt;&lt;/mrow&gt; &lt;mn&gt;82&lt;/mn&gt;&lt;/mmultiscripts&gt; &lt;mtext&gt;Rb&lt;/mtext&gt;&lt;/mrow&gt; &lt;/math&gt; , 1.58 ± 0.07 ns for &lt;math&gt; &lt;mrow&gt;&lt;mmultiscripts&gt;&lt;mrow&gt;&lt;/mrow&gt; &lt;mrow&gt;&lt;/mrow&gt; &lt;mn&gt;68&lt;/mn&gt;&lt;/mmultiscripts&gt; &lt;mtext&gt;Ga&lt;/mtext&gt;&lt;/mrow&gt; &lt;/math&gt; and 1.62 ± 0.01 ns for &lt;math&gt; &lt;mrow&gt;&lt;mmultiscripts&gt;&lt;mrow&gt;&lt;/mrow&gt; &lt;mrow&gt;&lt;/mrow&gt; &lt;mn&gt;124&lt;/mn&gt;&lt;/mmultiscripts&gt; &lt;mtext&gt;I&lt;/mtext&gt;&lt;/mrow&gt; &lt;/math&gt; . The impact of scatter and attenuation on the o-Ps lifetime was also assessed by analyzing a water-filled uniform cylinder (20 &lt;math&gt;&lt;mi&gt;ϕ&lt;/mi&gt;&lt;/math&gt; &lt;math&gt;&lt;mo&gt;×&lt;/mo&gt;&lt;/math&gt; 30","PeriodicalId":11559,"journal":{"name":"EJNMMI Physics","volume":"11 1","pages":"76"},"PeriodicalIF":3.0,"publicationDate":"2024-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11362402/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142105489","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":"Feasibility of a deep-inspiration breath-hold [¹⁸F]AlF-NOTA-LM3 PET/CT imaging on upper-abdominal lesions in NET patients: in comparison with respiratory-gated PET/CT.","authors":"Haiqiong Zhang, Meixi Liu, Ximin Shi, Jiangyu Ma, Chao Ren, Zhenghai Huang, Ying Wang, Hongli Jing, Li Huo","doi":"10.1186/s40658-024-00677-5","DOIUrl":"https://doi.org/10.1186/s40658-024-00677-5","url":null,"abstract":"<p><strong>Purposes: </strong>To explore the clinical feasibility and efficacy of a deep inspiration breath-hold (BH) PET/CT using [¹⁸F]AlF-NOTA-LM3 on upper abdominal lesions in patients with neuroendocrine tumors (NETs).</p><p><strong>Methods: </strong>Twenty-three patients underwent a free-breath (FB) whole-body PET/CT, including a 10 min/bed scan for the upper abdomen with a vital signal monitoring for respiratory gating (RG) followed by a 20-second BH PET/CT covering the same axial range. For the upper abdomen bed, the following PET series was reconstructed: a 2-min FB PET; RG PET (6 bins); a 20-second and 15-second BH PET (BH_15 and BH_20). Semi-quantitative analysis was performed to compare liver SUV_mean, lesion SUV_max, MTV, its percentage difference and target-to-background ratio (TBR) between both BH PET and RG PET images. Subgroup analysis considered lesion location, MTV and SUV_max. A 5-point Likert scale was used to perform visual analysis and any missed or additional lesions were identified compared with RG PET.</p><p><strong>Results: </strong>Quantitative analysis on overall lesions (n = 78) revealed higher SUV_max and TBR, and smaller MTV for both BH PET compared to FB and RG PET, with lesion location-specific variations. Neither significant difference was observed in all metrics between RG and FB PET in larger lesions, nor in MTV in lower-uptake lesions. However, both BH PET significantly enhanced these measurements. In the visual analysis, both BH PET showed noninferior performance to RG PET, and were evaluated clinically acceptable. Additional and missed lesions were observed in FB and both BH PET compared with RG PET, but didn't alter the clinical management. The BH_15 PET showed comparable performance to BH_20 PET in any comparison.</p><p><strong>Conclusion: </strong>The BH PET/CT using [¹⁸F]AlF-NOTA-LM3 is effective in detecting upper abdominal lesions, offering more accurate quantitative measurements. Using a novel PET/CT scanner, a 15-second BH PET can provide comparable and superior performance to RG PET, indicating potential feasibility in clinical routines.</p>","PeriodicalId":11559,"journal":{"name":"EJNMMI Physics","volume":"11 1","pages":"75"},"PeriodicalIF":3.0,"publicationDate":"2024-08-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11362407/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142105488","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":"Design and proof of concept of a double-panel TOF-PET system.","authors":"Andrea Gonzalez-Montoro, Noriel Pavón, Julio Barberá, Neus Cuarella, Antonio J González, Santiago Jiménez-Serrano, Alejandro Lucero, Laura Moliner, David Sánchez, Koldo Vidal, José M Benlloch","doi":"10.1186/s40658-024-00674-8","DOIUrl":"10.1186/s40658-024-00674-8","url":null,"abstract":"&lt;p&gt;&lt;strong&gt;Objective: &lt;/strong&gt;Positron Emission Tomography (PET) is a well-known imaging technology for the diagnosis, treatment, and monitoring of several diseases. Most PET scanners use a Ring-Shaped Detector Configuration (RSDC), which helps obtain homogeneous image quality but are restricted to an invariable Field-of-View (FOV), scarce spatial resolution, and low sensitivity. Alternatively, few PET systems use Open Detector Configurations (ODC) to permit an accessible FOV adaptable to different target sizes, thus optimizing sensitivity. Yet, to compensate the lack of angular coverage in ODC-PET, developing a detector with high-timing performance is mandatory to enable Time-of-Flight (TOF) techniques during reconstruction. The main goal of this work is to provide a proof of concept PET scanner appropriate for constructing the new generation of ODC-PET suitable for biopsy guidance and clinical intervention during acquisition. The designed detector has to be compact and robust, and its requirements in terms of performance are spatial and time resolutions &lt; 2 mm and &lt; 200 ps, respectively.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Methods: &lt;/strong&gt;The present work includes a simulation study of an ODC-PET based on 2-panels with variable distance. The image quality (IQ) and Derenzo phantoms have been simulated and evaluated. The phantom simulations have also been performed using a ring-shaped PET for comparison purposes of the ODC approach with conventional systems. Then, an experimental evaluation of a prototype detector that has been designed following the simulation results is presented. This study focused on tuning the ASIC parameters and evaluating the scintillator surface treatment (ESR and TiO&lt;sub&gt;2&lt;/sub&gt;), and configuration that yields the best Coincidence Time Resolution (CTR). Moreover, the scalability of the prototype to a module of 64 × 64mm&lt;sup&gt;2&lt;/sup&gt; and its preliminary evaluation regarding pixel identification are provided.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Results: &lt;/strong&gt;The simulation results reported sensitivity (%) values at the center of the FOV of 1.96, 1.63, and 1.18 for panel distances of 200, 250, and 300 mm, respectively. The IQ reconstructed image reported good uniformity (87%) and optimal CRC values, and the Derenzo phantom reconstruction suggests a system resolution of 1.6-2 mm. The experimental results demonstrate that using TiO&lt;sub&gt;2&lt;/sub&gt; coating yielded better detector performance than ESR. Acquired data was filtered by applying an energy window of ± 30% at the photopeak level. After filtering, best CTR of 230 ± 2 ps was achieved for an 8 × 8 LYSO pixel block with 2 × 2 × 12mm&lt;sup&gt;3&lt;/sup&gt; each. The detector performance remained constant after scaling-up the prototype to a module of 64 &lt;math&gt;&lt;mo&gt;×&lt;/mo&gt;&lt;/math&gt; 64mm&lt;sup&gt;2&lt;/sup&gt;, and the flood map demonstrates the module's capabilities to distinguish the small pixels; thus, a spatial resolution &lt; 2 mm (pixel size) is achieved.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Conclusions: &lt;/strong&gt;The simulated results of this biplanar scanner sh","PeriodicalId":11559,"journal":{"name":"EJNMMI Physics","volume":"11 1","pages":"73"},"PeriodicalIF":3.0,"publicationDate":"2024-08-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11341523/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142035469","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":"From SPECT/CT towards absolute quantification? - the case of unilateral condylar hyperplasia of the mandible.","authors":"Stijn De Schepper, Gopinath Gnanasegaran, Wouter De Vos, Elke Van de Casteele, John C Dickson, Tim Van den Wyngaert","doi":"10.1186/s40658-024-00676-6","DOIUrl":"10.1186/s40658-024-00676-6","url":null,"abstract":"<p><strong>Background: </strong>Unilateral condylar hyperplasia (UCH) of the mandible is a rare condition characterized by asymmetric growth of the mandibular condyles. Bone scintigraphy with SPECT(/CT) is commonly used to diagnose UCH and guide treatment. Still, varying results have been reported using the traditional threshold of 55%:45% in relative tracer uptake. While absolute quantification of uptake on SPECT/CT could improve results, optimal correction and reconstruction settings are currently unknown.</p><p><strong>Methods: </strong>Three anthropomorphic phantoms representing UCH were developed from patient CT volumes and produced using 3D printing technology. Fillable spherical inserts of different sizes (Ø: 8-15 mm) were placed in the condylar positions representing symmetrical and asymmetrical distributions. Recovery coefficients were determined for SPECT/CT using various reconstruction corrections, including attenuation and scatter correction (ACSC), resolution modeling (RM), and partial volume correction (PVC) using phantom measurements. Uptake ratios between condyles and condyle to clivus were evaluated. Finally, the impact of these correction techniques on absolute activity and diagnostic accuracy was assessed in a retrospective patient cohort for the diagnostic threshold of 55%:45%.</p><p><strong>Results: </strong>The activity was only partially recovered in all spherical inserts (range: 22.5-64.9%). However, RM improved relative recovery by 20.2-62.3% compared to ACSC. In the symmetric phantoms, the 95% confidence interval (CI) of condyle ratios included the diagnostic threshold (57.6%:42.4%) for UCH when using ACSC potentially leading to false positives, but not for ACSCRM datasets. Partial volume corrections coefficients from the NEMA IQ phantom was positionally dependent, with improvements seen performing PVC using coefficients derived from anthropomorphic phantoms. Retrospective application in a patient cohort showed only a weak linear correlation (R²: 0.25-0.67) and large limits of agreement (9.6-12.5%) between different reconstructions. Up to 44% of patients were reclassified using the 55%:45% threshold. Using clinical outcome data, ACSCRM had highest sensitivity (91%; 95% CI 59-100%) and specificity (66%; 95% CI 47-81%), significantly improving specificity (P = 0.038).</p><p><strong>Conclusions: </strong>Anthropomorphic phantoms were shown to be essential in determining optimal settings for acquisition, reconstruction, and analysis. SPECT/CT reconstructions with attenuation and scatter correction and resolution modeling are recommended and could improve specificity when using the 55%:45% threshold to assess condylar growth.</p>","PeriodicalId":11559,"journal":{"name":"EJNMMI Physics","volume":"11 1","pages":"74"},"PeriodicalIF":3.0,"publicationDate":"2024-08-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11343952/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142035470","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":"Subtraction of single-photon emission computed tomography (SPECT) in radioembolization: a comparison of four methods.","authors":"Camiel E M Kerckhaert, Hugo W A M de Jong, Marjolein B M Meddens, Rob van Rooij, Maarten L J Smits, Yothin Rakvongthai, Martijn M A Dietze","doi":"10.1186/s40658-024-00675-7","DOIUrl":"10.1186/s40658-024-00675-7","url":null,"abstract":"<p><strong>Background: </strong>Subtraction of single-photon emission computed tomography (SPECT) images has a number of clinical applications in e.g. foci localization in ictal/inter-ictal SPECT and defect detection in rest/stress cardiac SPECT. In this work, we investigated the technical performance of SPECT subtraction for the purpose of quantifying the effect of a vasoconstricting drug (angiotensin-II, or AT2) on the Tc-99m-MAA liver distribution in hepatic radioembolization using an innovative interventional hybrid C-arm scanner. Given that subtraction of SPECT images is challenging due to high noise levels and poor resolution, we compared four methods to obtain a difference image in terms of image quality and quantitative accuracy. These methods included (i) image subtraction: subtraction of independently reconstructed SPECT images, (ii) projection subtraction: reconstruction of a SPECT image from subtracted projections, (iii) projection addition: reconstruction by addition of projections as a background term during the iterative reconstruction, and (iv) image addition: simultaneous reconstruction of the difference image and the subtracted image.</p><p><strong>Results: </strong>Digital simulations (XCAT) and phantom studies (NEMA-IQ and anthropomorphic torso) showed that all four methods were able to generate difference images but their performance on specific metrics varied substantially. Image subtraction had the best quantitative performance (activity recovery coefficient) but had the worst visual quality (contrast-to-noise ratio) due to high noise levels. Projection subtraction showed a slightly better visual quality than image subtraction, but also a slightly worse quantitative accuracy. Projection addition had a substantial bias in its quantitative accuracy which increased with less counts in the projections. Image addition resulted in the best visual image quality but had a quantitative bias when the two images to subtract contained opposing features.</p><p><strong>Conclusion: </strong>All four investigated methods of SPECT subtraction demonstrated the capacity to generate a feasible difference image from two SPECT images. Image subtraction is recommended when the user is only interested in quantitative values, whereas image addition is recommended when the user requires the best visual image quality. Since quantitative accuracy is most important for the dosimetric investigation of AT2 in radioembolization, we recommend using the image subtraction method for this purpose.</p>","PeriodicalId":11559,"journal":{"name":"EJNMMI Physics","volume":"11 1","pages":"72"},"PeriodicalIF":3.0,"publicationDate":"2024-08-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11324633/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141981910","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":"Automatic reorientation to generate short-axis myocardial PET images.","authors":"Yuling Yang, Fanghu Wang, Xu Han, Hui Xu, Yangmei Zhang, Weiping Xu, Shuxia Wang, Lijun Lu","doi":"10.1186/s40658-024-00673-9","DOIUrl":"10.1186/s40658-024-00673-9","url":null,"abstract":"<p><strong>Background: </strong>Accurately redirecting reconstructed Positron emission tomography (PET) images into short-axis (SA) images shows great significance for subsequent clinical diagnosis. We developed a system for automatic redirection and quantitative analysis of myocardial PET images.</p><p><strong>Methods: </strong>A total of 128 patients were enrolled for 18 F-FDG PET/CT myocardial metabolic images (MMIs), including 3 image classifications: without defects, with defects, and excess uptake. The automatic reorientation system includes five modules: regional division, myocardial segmentation, ellipsoid fitting, image rotation and quantitative analysis. First, the left ventricular geometry-based canny edge detection (LVG-CED) was developed and compared with the other 5 common region segmentation algorithms, the optimized partitioning was determined based on partition success rate. Then, 9 myocardial segmentation methods and 4 ellipsoid fitting methods were combined to derive 36 cross combinations for diagnostic performance in terms of Pearson correlation coefficient (PCC), Kendall correlation coefficient (KCC), Spearman correlation coefficient (SCC), and determination coefficient. Finally, the deflection angles were computed by ellipsoid fitting and the SA images were derived by affine transformation. Furthermore, the polar maps were used for quantitative analysis of SA images, and the redirection effects of 3 different image classifications were analyzed using correlation coefficients.</p><p><strong>Results: </strong>On the dataset, LVG-CED outperformed other methods in the regional division module with a 100% success rate. In 36 cross combinations, PSO-FCM and LLS-SVD performed the best in terms of correlation coefficient. The linear results indicate that our algorithm (LVG-CED, PSO-FCM, and LLS-SVD) has good consistency with the reference manual method. In quantitative analysis, the similarities between our method and the reference manual method were higher than 96% at 17 segments. Moreover, our method demonstrated excellent performance in all 3 image classifications.</p><p><strong>Conclusion: </strong>Our algorithm system could realize accurate automatic reorientation and quantitative analysis of PET MMIs, which is also effective for images suffering from interference.</p>","PeriodicalId":11559,"journal":{"name":"EJNMMI Physics","volume":"11 1","pages":"70"},"PeriodicalIF":3.0,"publicationDate":"2024-08-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11294504/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141874487","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":"Dosimetric implications of kidney anatomical volume changes in ¹⁷⁷Lu-DOTATATE therapy.","authors":"Jehangir Khan, Tobias Rydèn, Martijn Van Essen, Johanna Svensson, Joseph Grudzinski, Peter Bernhardt","doi":"10.1186/s40658-024-00672-w","DOIUrl":"10.1186/s40658-024-00672-w","url":null,"abstract":"&lt;p&gt;&lt;strong&gt;Introduction: &lt;/strong&gt;This study aims to evaluate the use of CT-based whole kidney parenchyma (WKP) segmentation in &lt;sup&gt;177&lt;/sup&gt;Lu-DOTATATE dosimetry. Specifically, it investigates whether WKP volumes change during treatment and evaluates the accuracy of applying a single delineated WKP volume for dosimetry. Furthermore, it aims to determine the cause of WKP volume changes-whether caused by radiation or amino acid infusion-by comparing them with spleen volume changes as a marker for radiation-induced alterations.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Methods: &lt;/strong&gt;SPECT/CT images of 18 patients were acquired over the abdomen approximately 4 h (h) (D0), 24 h (D1), 48 h (D2) and 168 h (D7) post-administration of &lt;sup&gt;177&lt;/sup&gt;Lu-DOTATATE. CT guided WKP volumes were measured before (baseline) and during treatment. Kidney activity concentrations at each time point were derived from CT-segmented WKP overlaid on SPECT scans. The accuracy of using WKP segmentation from a single CT for all time points was assessed against the gold standard of segmenting each WKP individually. Time-integrated activity calculations were based on a tri-exponential curve fit of the kidney activity concentration over time. Kidney absorbed doses were estimated under the assumption of local energy deposition. Additionally, the impact of various partial volume correction methods on dosimetry was evaluated.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Results: &lt;/strong&gt;Whole-kidney parenchyma (WKP) volumes, ranging from 31 to 243 mL, showed a gradual increase from baseline (mean ± SD = 130.6 ± 46.1 mL) at the initial time points D0 (138.5 ± 44.7 mL) and D1 (139.4 ± 41.6 mL), followed by a slight decrease at D2 (132.8 ± 44.5 mL) and a further decrease at D7 (129.2 ± 42.7 mL). The volume increase at D0 and D1 was statistically significant. Spleen volume did not change during treatment, suggesting that amino acid infusion rather than irradiation effects caused WKP volume changes. Bland-Altman analysis revealed WKP volume biases of 8.77% (D0 vs. B&lt;sub&gt;L&lt;/sub&gt;), 10.77% (D1 vs. B&lt;sub&gt;L&lt;/sub&gt;), 1.10% (D2 vs. B&lt;sub&gt;L&lt;/sub&gt;), and 1.10% (D7 vs. B&lt;sub&gt;L&lt;/sub&gt;), with corresponding uncertainties of 24.4%, 23.6%, 25.4%, and 25.4%, respectively. When WKP segmentation from a single CT is applied across all SPECTs, these WKP volume changes could overestimate the activity concentration and mean absorbed doses up to 4.3% and 2.5%, respectively. The absorbed dose uncertainties using a recovery coefficient (RC) of 0.85 for single-time-point WKP delineation increase the absorbed dose uncertainty by 4% compared to the use of patient-specific RCs and time specific segmentation of WKP volumes.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Conclusions: &lt;/strong&gt;Kidney volume exhibited significant variation form D0 to D7, affecting the precision of dosimetry calculation, primarily due to errors in whole-kidney parenchyma (WKP) delineation. Notably, using WKP segmentation from a single CT scan applied to sequential SPECT images introduce further uncertainty and may lead to a","PeriodicalId":11559,"journal":{"name":"EJNMMI Physics","volume":"11 1","pages":"71"},"PeriodicalIF":3.0,"publicationDate":"2024-08-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11294297/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141874488","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":"Estimation of kidney doses from [¹⁷⁷Lu]Lu-DOTA-TATE PRRT using single time point post-treatment SPECT/CT.","authors":"Safia Spink, Daniel Gillett, Sarah Heard, Ines Harper, Ruth Casey, Luigi Aloj","doi":"10.1186/s40658-024-00665-9","DOIUrl":"10.1186/s40658-024-00665-9","url":null,"abstract":"<p><strong>Background: </strong>Dosimetry after [¹⁷⁷Lu]Lu-DOTA-TATE therapy can be demanding for both patients and the clinical service due to the need for imaging at several time points. In this work we compare three methods of single time point (STP) kidney dosimetry after [¹⁷⁷Lu]Lu-DOTA-TATE therapy with a multiple time point (MTP) dosimetry method.</p><p><strong>Method: </strong>Method 1 (MTP): Kidney doses were calculated from 31 patients including 107 therapy cycles. Post-therapy SPECT images were acquired on day 0, 4 and 7 along with a CT scan on day 4. A mono-exponential fit was used to calculate kidney doses using cycle specific data. Method 2 (Consistent effective half-life): The effective half-life [Formula: see text] calculated in cycle 1 was assumed consistent for subsequent cycles of therapy and the activity scaled using a single day 3-5 SPECT/CT. Methods 3 and 4 (Hänscheid and Madsen approximations): The Hänscheid approximation and Madsen approximation were both evaluated using a single SPECT/CT acquired on day 0, 4 and 7. All STP methods were compared to the MTP method for accuracy.</p><p><strong>Results: </strong>Using the MTP method, mean right and left kidney doses were calculated to be 2.9 ± 1.1 Gy and 2.8 ± 0.9 Gy respectively and the population [Formula: see text] was 56 ± 13 h. For the consistent [Formula: see text], Hänscheid and Madsen methods, the percentage of results within ± 20% of MTP method were 96% (n = 70), 95% (n = 80) and 94% (n = 80) respectively.</p><p><strong>Conclusion: </strong>All three single time point methods had > 94% of results within ± 20% of the MTP method, however the consistent [Formula: see text] method resulted in the highest alignment with the MTP method and is the only method which allows for calculation of the patient-specific [Formula: see text]. If only a single scan can be performed, day 4 is optimal for kidney dosimetry where the Hänscheid or Madsen approximation can be implemented with good accuracy.</p>","PeriodicalId":11559,"journal":{"name":"EJNMMI Physics","volume":"11 1","pages":"68"},"PeriodicalIF":3.0,"publicationDate":"2024-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11272758/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141757806","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}