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Klein A, Kosinski L, Loupy A, Frey E, Stegall M, Helanterä I, Newell K, Meier-Kriesche HU, Mannon RB, Fitzsimmons WE. Comparing the prognostic performance of iBOX and biopsy-proven acute rejection for long-term kidney graft survival. Am J Transplant 2024:S1600-6135(24)00275-2. [PMID: 38642711 DOI: 10.1016/j.ajt.2024.04.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2023] [Revised: 03/20/2024] [Accepted: 04/08/2024] [Indexed: 04/22/2024]
Abstract
Biopsy-proven acute rejection (BPAR) occurs in approximately 10% of kidney transplant recipients in the first year, making superiority trials unfeasible. iBOX, a quantitative composite of estimated glomerular filtration rate, proteinuria, antihuman leukocyte antigen donor-specific antibody, and + full/- abbreviated kidney histopathology, is a new proposed surrogate endpoint. BPAR's prognostic ability was compared with iBOX in a pooled cohort of 1534 kidney transplant recipients from 4 data sets, including 2 prospective randomized controlled trials. Discrimination analyses showed mean c-statistic differences between both iBOX compared with BPAR of 0.25 (95% confidence interval: 0.17-0.32) for full iBOX and 0.24 (95% confidence interval: 0.16-0.32) for abbreviated iBOX, indicating statistically significantly higher c-statistic values for the iBOX prognosis of death-censored graft survival. Mean (± standard error) c-statistics were 0.81 ± 0.03 for full iBOX, 0.80 ± 0.03 for abbreviated iBOX, and 0.57 ± 0.03 for BPAR. In calibration analyses, predicted graft loss events from both iBOX models were not significantly different from those observed. However, for BPAR, the predicted events were significantly (P < .01) different (observed: 64; predicted: 70; full iBOX: 76; abbreviated iBOX: 173 BPAR). IBOX at 1-year posttransplant is superior to BPAR in the first year posttransplant in graft loss prognostic performance, providing valuable additional information and facilitating the demonstration of superiority of novel immunosuppressive regimens.
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Affiliation(s)
| | | | - Alexandre Loupy
- Université de Paris, Cité, Institut national de la santé et de la recherche médicale, U970, PARCC, Paris Translational Research Centre for Organ Transplantation, Paris, France
| | - Eric Frey
- Critical Path Institute, Tucson, Arizona, USA
| | - Mark Stegall
- Department of Surgery, Mayo Clinic, Rochester, Minnesota, USA
| | - Ilkka Helanterä
- Helsinki University Hospital, Department of Transplantation and Liver Surgery, and University of Helsinki, Finland
| | - Kenneth Newell
- Division of Transplantation, Department of Surgery, Emory University School of Medicine, Atlanta, Georgia, USA
| | | | - Roslyn B Mannon
- Department of Medicine, Division of Nephrology, University of Nebraska Medical Center, Omaha, Nebraska, USA
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2
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Klein A, Loupy A, Stegall M, Helanterä I, Kosinski L, Frey E, Aubert O, Divard G, Newell K, Meier-Kriesche HU, Mannon RB, Dumortier T, Aggarwal V, Podichetty JT, O'Doherty I, Gaber AO, Fitzsimmons WE. Qualifying a novel clinical trial endpoint (iBOX) predictive of long-term kidney transplant outcomes. Am J Transplant 2023; 23:1496-1506. [PMID: 37735044 DOI: 10.1016/j.ajt.2023.04.018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2022] [Revised: 03/30/2023] [Accepted: 04/12/2023] [Indexed: 09/23/2023]
Abstract
New immunosuppressive therapies that improve long-term graft survival are needed in kidney transplant. Critical Path Institute's Transplant Therapeutics Consortium received a qualification opinion for the iBOX Scoring System as a novel secondary efficacy endpoint for kidney transplant clinical trials through European Medicines Agency's qualification of novel methodologies for drug development. This is the first qualified endpoint for any transplant indication and is now available for use in kidney transplant clinical trials. Although the current efficacy failure endpoint has typically shown the noninferiority of therapeutic regimens, the iBOX Scoring System can be used to demonstrate the superiority of a new immunosuppressive therapy compared to the standard of care from 6 months to 24 months posttransplant in pivotal or exploratory drug therapeutic studies.
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Affiliation(s)
| | - Alexandre Loupy
- Université de Paris, Cité, Institut national de la santé et de la recherche médicale, U970, PARCC, Paris Translational Research Centre for Organ Transplantation, Paris, France
| | - Mark Stegall
- Department of Surgery, Mayo Clinic, Rochester, Minnesota, USA
| | - Ilkka Helanterä
- Department of Transplantation and Liver Surgery, Helsinki University Hospital, Helsinki, Finland
| | | | - Eric Frey
- Critical Path Institute, Tucson, Arizona, USA
| | - Olivier Aubert
- Université de Paris, Cité, Institut national de la santé et de la recherche médicale, U970, PARCC, Paris Translational Research Centre for Organ Transplantation, Paris, France
| | - Gillian Divard
- Université de Paris, Cité, Institut national de la santé et de la recherche médicale, U970, PARCC, Paris Translational Research Centre for Organ Transplantation, Paris, France
| | - Kenneth Newell
- Division of Transplantation, Department of Surgery, Emory University School of Medicine, Atlanta, Georgia, USA
| | | | - Roslyn B Mannon
- Department of Medicine, Division of Nephrology, University of Nebraska Medical Center, Omaha, Nebraska, USA
| | | | | | | | | | - Ahmed Osama Gaber
- Department of Surgery, Houston Methodist Hospital, Houston, Texas, USA, and Weill Cornell Medicine, New York, New York, USA
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3
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Klein A, Loupy A, Stegall M, Helanterä I, Kosinski L, Frey E, Aubert O, Divard G, Newell K, Meier-Kriesche HU, Mannon R, Dumortier T, Aggarwal V, Podichetty JT, O’Doherty I, Gaber AO, Fitzsimmons WE. Qualifying a Novel Clinical Trial Endpoint (iBOX) Predictive of Long-Term Kidney Transplant Outcomes. Transpl Int 2023; 36:11951. [PMID: 37822449 PMCID: PMC10563802 DOI: 10.3389/ti.2023.11951] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2022] [Accepted: 04/12/2023] [Indexed: 10/13/2023]
Abstract
New immunosuppressive therapies that improve long-term graft survival are needed in kidney transplant. Critical Path Institute's Transplant Therapeutics Consortium received a qualification opinion for the iBOX Scoring System as a novel secondary efficacy endpoint for kidney transplant clinical trials through European Medicines Agency's qualification of novel methodologies for drug development. This is the first qualified endpoint for any transplant indication and is now available for use in kidney transplant clinical trials. Although the current efficacy failure endpoint has typically shown the noninferiority of therapeutic regimens, the iBOX Scoring System can be used to demonstrate the superiority of a new immunosuppressive therapy compared to the standard of care from 6 months to 24 months posttransplant in pivotal or exploratory drug therapeutic studies.
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Affiliation(s)
- Amanda Klein
- Critical Path Institute, Tucson, AZ, United States
| | - Alexandre Loupy
- Institut National de la Santé et de la Recherche Médicale (INSERM), Paris, France
| | - Mark Stegall
- Department of Surgery, Mayo Clinic, Rochester, Rochester, MN, United States
| | - Ilkka Helanterä
- Department of Transplantation and Liver Surgery, Helsinki University Central Hospital, Helsinki, Finland
| | | | - Eric Frey
- Critical Path Institute, Tucson, AZ, United States
| | - Olivier Aubert
- Institut National de la Santé et de la Recherche Médicale (INSERM), Paris, France
| | - Gillian Divard
- Institut National de la Santé et de la Recherche Médicale (INSERM), Paris, France
| | - Kenneth Newell
- Division of Transplantation, Department of Surgery, Emory University School of Medicine, Atlanta, GA, United States
| | | | - Roslyn Mannon
- Division of Nephrology, Department of Internal Medicine, College of Medicine, University of Nebraska Medical Center, Omaha, NE, United States
| | | | | | | | | | - Ahmed Osama Gaber
- Department of Surgery, Houston Methodist Hospital, Houston, TX, United States
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4
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Kosinski L, Frey E, Klein A, O'Doherty I, Romero K, Stegall M, Helanterä I, Gaber AO, Fitzsimmons WE, Aggarwal V. Longitudinal estimated glomerular filtration rate (eGFR) modeling in long-term renal function to inform clinical trial design in kidney transplantation. Clin Transl Sci 2023; 16:1680-1690. [PMID: 37350196 PMCID: PMC10499426 DOI: 10.1111/cts.13579] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2023] [Accepted: 06/10/2023] [Indexed: 06/24/2023] Open
Abstract
Kidney transplantation is the preferred treatment for individuals with end-stage kidney disease. From a modeling perspective, our understanding of kidney function trajectories after transplantation remains limited. Current modeling of kidney function post-transplantation is focused on linear slopes or percent decline and often excludes the highly variable early timepoints post-transplantation, where kidney function recovers and then stabilizes. Using estimated glomerular filtration rate (eGFR), a well-known biomarker of kidney function, from an aggregated dataset of 4904 kidney transplant patients including both observational studies and clinical trials, we developed a longitudinal model of kidney function trajectories from time of transplant to 6 years post-transplant. Our model is a nonlinear, mixed-effects model built in NONMEM that captured both the recovery phase after kidney transplantation, where the graft recovers function, and the long-term phase of stabilization and slow decline. Model fit was assessed using diagnostic plots and individual fits. Model performance, assessed via visual predictive checks, suggests accurate model predictions of eGFR at the median and lower 95% quantiles of eGFR, ranges which are of critical clinical importance for assessing loss of kidney function. Various clinically relevant covariates were also explored and found to improve the model. For example, transplant recipients of deceased donors recover function more slowly after transplantation and calcineurin inhibitor use promotes faster long-term decay. Our work provides a generalizable, nonlinear model of kidney allograft function that will be useful for estimating eGFR up to 6 years post-transplant in various clinically relevant populations.
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Affiliation(s)
| | - Eric Frey
- Critical Path InstituteTucsonArizonaUSA
| | | | | | | | - Mark Stegall
- Department of SurgeryMayo ClinicRochesterMinnesotaUSA
| | - Ilkka Helanterä
- Department of Transplantation and Liver SurgeryHelsinki University HospitalHelsinkiFinland
| | - Ahmed Osama Gaber
- Department of Surgery, Houston Methodist HospitalHoustonTexasUSA
- Weill Cornell MedicineNew YorkNew YorkUSA
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Brosch-Lenz J, Ke S, Wang H, Frey E, Dewaraja YK, Sunderland J, Uribe C. An International Study of Factors Affecting Variability of Dosimetry Calculations, Part 2: Overall Variabilities in Absorbed Dose. J Nucl Med 2023; 64:1109-1116. [PMID: 37024302 PMCID: PMC10315703 DOI: 10.2967/jnumed.122.265094] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2022] [Revised: 02/07/2023] [Accepted: 02/07/2023] [Indexed: 04/08/2023] Open
Abstract
Dosimetry for personalized radiopharmaceutical therapy has gained considerable attention. Many methods, tools, and workflows have been developed to estimate absorbed dose (AD). However, standardization is still required to reduce variability of AD estimates across centers. One effort for standardization is the Society of Nuclear Medicine and Molecular Imaging 177Lu Dosimetry Challenge, which comprised 5 tasks (T1-T5) designed to assess dose estimate variability associated with the imaging protocol (T1 vs. T2 vs. T3), segmentation (T1 vs. T4), time integration (T4 vs. T5), and dose calculation (T5) steps of the dosimetry workflow. The aim of this work was to assess the overall variability in AD calculations for the different tasks. Methods: Anonymized datasets consisting of serial planar and quantitative SPECT/CT scans, organ and lesion contours, and time-integrated activity maps of 2 patients treated with 177Lu-DOTATATE were made available globally for participants to perform dosimetry calculations and submit their results in standardized submission spreadsheets. The data were carefully curated for formal mistakes and methodologic errors. General descriptive statistics for ADs were calculated, and statistical analysis was performed to compare the results of different tasks. Variability in ADs was measured using the quartile coefficient of dispersion. Results: ADs to organs estimated from planar imaging protocols (T2) were lower by about 60% than those from pure SPECT/CT (T1), and the differences were statistically significant. Importantly, the average differences in dose estimates when at least 1 SPECT/CT acquisition was available (T1, T3, T4, T5) were within ±10%, and the differences with respect to T1 were not statistically significant for most organs and lesions. When serial SPECT/CT images were used, the quartile coefficients of dispersion of ADs for organs and lesions were on average less than 20% and 26%, respectively, for T1; 20% and 18%, respectively, for T4 (segmentations provided); and 10% and 5%, respectively, for T5 (segmentation and time-integrated activity images provided). Conclusion: Variability in ADs was reduced as segmentation and time-integration data were provided to participants. Our results suggest that SPECT/CT-based imaging protocols generate more consistent and less variable results than planar imaging methods. Effort at standardizing segmentation and fitting should be made, as this may substantially reduce variability in ADs.
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Affiliation(s)
- Julia Brosch-Lenz
- Department of Integrative Oncology, BC Cancer Research Institute, Vancouver, British Columbia, Canada
| | - Suqi Ke
- Division of Quantitative Sciences, Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Hao Wang
- Division of Quantitative Sciences, Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Eric Frey
- Rapid, LLC, Baltimore, Maryland
- Department of Radiology, Johns Hopkins University, Baltimore, Maryland
| | - Yuni K Dewaraja
- Department of Radiology, University of Michigan, Ann Arbor, Michigan
| | - John Sunderland
- Department of Radiology, University of Iowa, Iowa City, Iowa
| | - Carlos Uribe
- Department of Integrative Oncology, BC Cancer Research Institute, Vancouver, British Columbia, Canada;
- Department of Functional Imaging, BC Cancer, Vancouver, British Columbia, Canada; and
- Department of Radiology, University of British Columbia, Vancouver, British Columbia, Canada
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6
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Frey E, Kedrowicz A, Hedgpeth MW. Exploring companion animal caretakers' attitudes, perceptions and behavioural drivers of antimicrobial use within the social context of veterinary care. J Small Anim Pract 2022; 63:873-881. [PMID: 36084956 PMCID: PMC10086989 DOI: 10.1111/jsap.13549] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2022] [Revised: 06/29/2022] [Accepted: 07/24/2022] [Indexed: 11/28/2022]
Abstract
OBJECTIVE To explore companion animal caretakers' attitudes, perceptions and behavioural drivers of antimicrobial use within the social context of veterinary care. MATERIALS AND METHODS Five semi-structured focus groups were conducted with 26 cat and dog owners. Transcripts were subjected to thematic analysis to systematically code and classify themes related to the study objectives. RESULTS Thematic analysis revealed five themes - trust-building/relationships, shared decision-making/empowerment, clear communication, judicious use and concerns surrounding antimicrobial use. Strong veterinarian-client relationships were the underlying factor influencing acceptance of antimicrobial use stewardship principles. Participants viewed themselves as advocates for their animals and preferred a relationship-centred approach to care facilitated through competent communication. They cited the importance of clear communication related to diagnosis and antimicrobial recommendations including using client-friendly terminology, providing explicit instructions for antimicrobial use, and having a shared plan for next steps and follow-up communication. Participants reported challenges with administering antimicrobial drugs, expressed concerns with potential side effects and development of antimicrobial resistance. Consequently, they reported an interest in alternatives to antimicrobial drugs and a focus on preventive medicine that was counterbalanced with concerns for animal comfort and welfare. CLINICAL SIGNIFICANCE Conversations about antimicrobial use can be reframed to include alternatives to antimicrobials as part of the treatment plan, and clients can be empowered to play a more active role in their animals' care. Veterinarians can apply core communication skills to advance antimicrobial stewardship principles and thereby contribute to preserving the effectiveness and availability of antimicrobials while preserving the trusting relationship and shared decision-making between clients and veterinarians.
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Affiliation(s)
- E Frey
- College of Veterinary Medicine, North Carolina State University, Raleigh, North Carolina, 27607, USA
| | - A Kedrowicz
- College of Veterinary Medicine, North Carolina State University, Raleigh, North Carolina, 27607, USA
| | - M W Hedgpeth
- College of Veterinary Medicine, North Carolina State University, Raleigh, North Carolina, 27607, USA
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7
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Subramanian S, He B, Frey E, Jokisch DW, Bolch W, Sgouros G. Improved accuracy of S-value-based dosimetry: a guide to transition from Cristy-Eckerman to ICRP adult phantoms. EJNMMI Phys 2022; 9:57. [PMID: 36018453 PMCID: PMC9418401 DOI: 10.1186/s40658-022-00485-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2022] [Accepted: 08/08/2022] [Indexed: 12/03/2022] Open
Abstract
Background In 2016, the International Commission on Radiological Protection (ICRP) published the results of Monte Carlo simulations performed using updated and anatomically realistic voxelized phantoms. The resulting specific absorbed fractions are based on more realistic human anatomy than those computed in the stylized, geometrical Cristy–Eckerman (CE) phantom. Despite this development, the ICRP-absorbed fractions have not been widely adopted for radiopharmaceutical dosimetry. To help make the transition, we have established a correspondence between source and target tissues defined in the CE phantom and those defined in the ICRP phantoms. Results The ICRP phantom has 79 source regions and 43 target regions in comparison with the 23 source and 18 target tissue regions defined in the CE phantom. The ICRP phantom provides tissue regions with greater anatomical detail. Some of this additional detail is focused on radiation protection and dosimetry of inhaled/ingested radioactivity. Some, but not all, of this detail is useful and appropriate for radiopharmaceutical therapy. We have established the correspondence between CE and ICRP phantom source and target regions and attempted to highlight the ICRP source tissues relevant to radiopharmaceutical therapy (RPT). This paper provides tables and figures highlighting the correspondences established. Conclusion The results provide assistance in transitioning from CE-stylized phantoms to the anatomically accurate voxelized ICRP phantoms. It provides specific guidance for porting the total absorbed activity for regions as defined in the CE phantom to regions within the ICRP phantoms.
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Affiliation(s)
| | - Bin He
- Radiopharmaceutical Imaging and Dosimetry, LLC (Rapid), Baltimore, MD, USA
| | - Eric Frey
- Radiopharmaceutical Imaging and Dosimetry, LLC (Rapid), Baltimore, MD, USA.,The Russell H. Morgan Department of Radiology and Radiological Science, School of Medicine, Johns Hopkins University, Baltimore, MD, USA
| | - Derek W Jokisch
- Department of Physics and Engineering, Francis Marion University, Florence, SC, USA.,Center for Radiation Protection Knowledge, Oak Ridge National Laboratory, Oak Ridge, TN, USA
| | - Wesley Bolch
- J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, Gainesville, FL, USA
| | - George Sgouros
- Radiopharmaceutical Imaging and Dosimetry, LLC (Rapid), Baltimore, MD, USA.,The Russell H. Morgan Department of Radiology and Radiological Science, School of Medicine, Johns Hopkins University, Baltimore, MD, USA
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8
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Uribe C, Peterson A, Van B, Fedrigo R, Carlson J, Sunderland J, Frey E, Dewaraja YK. An International Study of Factors Affecting Variability of Dosimetry Calculations, Part 1: Design and Early Results of the SNMMI Dosimetry Challenge. J Nucl Med 2021; 62:36S-47S. [PMID: 34857620 DOI: 10.2967/jnumed.121.262748] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2021] [Revised: 09/30/2021] [Indexed: 11/16/2022] Open
Abstract
In this work, we present details and initial results from a 177Lu dosimetry challenge that has been designed to collect data from the global nuclear medicine community aiming at identifying, understanding, and quantitatively characterizing the consequences of the various sources of variability in dosimetry. Methods: The challenge covers different approaches to performing dosimetry: planar, hybrid, and pure SPECT. It consists of 5 different and independent tasks to measure the variability of each step in the dosimetry workflow. Each task involves the calculation of absorbed doses to organs and tumors and was meant to be performed in sequential order. The order of the tasks is such that results from a previous one would not affect subsequent ones. Different sources of variability are removed as the participants advance through the challenge by giving them the data required to begin the calculations at different steps of the dosimetry workflow. Data from 2 patients after a therapeutic administration of 177Lu-DOTATATE were used for this study. The data are hosted in Deep Blue Data, a data repository service run by the University of Michigan. Participants submit results in standardized spreadsheets and with a short description summarizing their methods. Results: In total, 178 participants have signed up for the challenge, and 119 submissions have been received. Sixty percent of submissions have used voxelized dose methods, with 47% of those using commercial software. In initial analysis, the volume of organs showed a variability of up to 49.8% whereas for lesions this was up to 176%. Variability in time-integrated activity was up to 192%. Mean absorbed doses varied up to 57.7%. Segmentation is the step that required the longest time to complete, with a median of 43 min. The median total time to perform the full calculation was 89 min. Conclusion: To advance dosimetry and encourage its routine use in radiopharmaceutical therapy applications, it is critical that dosimetry results be reproducible across centers. Our initial results provide insights into the variability associated with performing dose calculations. It is expected that this dataset, including results from future stages, will result in efforts to standardize and harmonize methods and procedures.
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Affiliation(s)
- Carlos Uribe
- Functional Imaging, BC Cancer, Vancouver, British Columbia, Canada; .,Department of Radiology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Avery Peterson
- Department of Radiology, University of Michigan Medical School, Ann Arbor, Michigan
| | - Benjamin Van
- Department of Radiology, University of Michigan Medical School, Ann Arbor, Michigan
| | - Roberto Fedrigo
- Department of Integrative Oncology, BC Cancer Research Institute, Vancouver, British Columbia, Canada
| | - Jake Carlson
- U-M Library, University of Michigan, Ann Arbor, Michigan
| | - John Sunderland
- Department of Radiology, University of Iowa, Iowa City, Iowa
| | - Eric Frey
- Radiological Physics Division, Johns Hopkins University, Baltimore, Maryland; and.,Rapid, LLC, Baltimore, Maryland
| | - Yuni K Dewaraja
- Department of Radiology, University of Michigan Medical School, Ann Arbor, Michigan
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Sgouros G, Frey E, Du Y, Hobbs R, Bolch W. Imaging and dosimetry for alpha-particle emitter radiopharmaceutical therapy: improving radiopharmaceutical therapy by looking into the black box. Eur J Nucl Med Mol Imaging 2021; 49:18-29. [PMID: 34782911 DOI: 10.1007/s00259-021-05583-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2021] [Accepted: 10/09/2021] [Indexed: 02/07/2023]
Abstract
Radiopharmaceutical therapy using α-particle emitting radionuclides (αRPT) is a novel treatment modality that delivers highly potent alpha-particles to cancer cells or their environment. We review the advantages and challenges of imaging and dosimetry in implementing αRPT for cancer patients.
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Affiliation(s)
| | - Eric Frey
- Johns Hopkins University, Baltimore, MD, USA
| | - Yong Du
- Johns Hopkins University, Baltimore, MD, USA
| | - Rob Hobbs
- Johns Hopkins University, Baltimore, MD, USA
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10
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Santhanam P, Solnes L, Nath T, Roussin JP, Gray D, Frey E, Sgouros G, Ladenson PW. Real-time quantitation of thyroidal radioiodine uptake in thyroid disease with monitoring by a collar detection device. Sci Rep 2021; 11:18479. [PMID: 34531443 PMCID: PMC8446004 DOI: 10.1038/s41598-021-97408-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2021] [Accepted: 08/25/2021] [Indexed: 11/30/2022] Open
Abstract
Radioactive iodine (RAI) is safe and effective in most patients with hyperthyroidism but not all individuals are cured by the first dose, and most develop post-RAI hypothyroidism. Postoperative RAI therapy for remnant ablation is successful in 80–90% of thyroid cancer patients and sometimes induces remission of nonresectable cervical and/or distant metastatic disease but the effective tumor dose is usually not precisely known and must be moderated to avoid short- and long-term adverse effects on other tissues. The Collar Therapy Indicator (COTI) is a radiation detection device embedded in a cloth collar secured around the patient’s neck and connected to a recording and data transmission box. In previously published experience, the data can be collected at multiple time points, reflecting local cervical RAI exposure and correlating well with conventional methods. We evaluated the real-time uptake of RAI in patients with hyperthyroid Graves’ disease and thyroid cancer. We performed a pilot feasibility prospective study. Data were analyzed using R© (version 4.0.3, The R Foundation for Statistical Computing, 2020), and Python (version 3.6, Matplotlib version 3.0.3). The COTI was able to provide a quantitative temporal pattern of uptake within the thyroid in persons with Graves’ disease and lateralized the remnant tissue in persons with thyroid cancer. The study has demonstrated that the portable collar radiation detection device outside of a healthcare facility is accurate and feasible for use after administration of RAI for diagnostic studies and therapy to provide a complete collection of fractional target radioactivity data compared to that traditionally acquired with clinic-based measurements at one or two time-points. Clinical Trials Registration NCT03517579, DOR 5/7/2018.
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Affiliation(s)
- Prasanna Santhanam
- Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, Johns Hopkins University School of Medicine, 1830 E. Monument St./Ste. 333, Baltimore, MD, 21287, USA.
| | - Lilja Solnes
- Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD, 21287, USA
| | - Tanmay Nath
- Department of Biostatistics, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, 21287, USA
| | | | | | - Eric Frey
- Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD, 21287, USA
| | - George Sgouros
- Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD, 21287, USA
| | - Paul W Ladenson
- Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, Johns Hopkins University School of Medicine, 1830 E. Monument St./Ste. 333, Baltimore, MD, 21287, USA
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11
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Roncali E, Capala J, Benedict SH, Akabani G, Bednarz B, Bhadrasain V, Bolch WE, Buchsbaum JC, Coleman NC, Dewaraja YK, Frey E, Ghaly M, Grudzinski J, Hobbs RF, Howell RW, Humm JL, Kunos CA, Larson S, Lin FI, Madsen M, Mirzadeh S, Morse D, Pryma D, Sgouros G, St. James S, Wahl RL, Xiao Y, Zanzonico P, Zukotynski K. Overview of the First NRG Oncology–National Cancer Institute Workshop on Dosimetry of Systemic Radiopharmaceutical Therapy. J Nucl Med 2020; 62:1133-1139. [DOI: 10.2967/jnumed.120.255547] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2020] [Accepted: 11/20/2021] [Indexed: 11/16/2022] Open
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12
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Olguin E, President B, Ghaly M, Frey E, Sgouros G, Bolch WE. Specific absorbed fractions and radionuclide S-values for tumors of varying size and composition. Phys Med Biol 2020; 65:235015. [PMID: 32992308 DOI: 10.1088/1361-6560/abbc7e] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Accurate estimates of tumor absorbed dose are essential for the evaluation of treatment efficacy in radiopharmaceutical cancer therapy. Although tumor dosimetry via the MIRD schema has been previously investigated, prior studies have been limited to the consideration of soft-tissue tumors. In the present study, specific absorbed fractions (SAFs) for monoenergetic photons, electrons, and alpha particles in tumors of varying compositions were computed using Monte Carlo simulations in MCNPX after which self-irradiation S-values for 22 radionuclides (along with 14 additional alpha-emitter progeny) were generated for tumors of both varying size and tissue composition. The tumors were modeled as spheres with radii ranging from 0.10 cm to 6.0 cm and with compositions varying from 100% soft tissue (ST) to 100% mineral bone (MB). The energies of the photons and electrons were varied on a logarithm energy grid from 10 keV to 10 MeV. The energies of alpha particles were varied along a linear energy grid from 0.5 MeV to 12 MeV. In all cases, a homogenous activity distribution was assumed throughout the tumor volume. Furthermore, to assess the effect of tumor shape, several ellipsoidal tumors of different compositions were modeled and absorbed fractions were computed for monoenergetic electrons and photons. S-values were then generated using detailed decay data from the 2008 MIRD Monograph on Radionuclide Data and Decay Schemes. Our study results demonstrate that a soft-tissue model yields relative errors of 25% and 71% in the absorbed fraction assigned to uniform sources of 1.5 MeV electrons and 100 keV photons, respectively, localized within a 1 cm diameter tumor of MB. The data further show that absorbed fractions for moderate ellipsoids can be well approximated by a spherical shape of equal mass within a relative error of < 8%. S-values for 22 radionuclides (and their daughter progeny) were computed with results demonstrating how relative errors in SAFs could propagate to relative errors in tumor dose estimates as high as 86%. A comprehensive data set of radionuclide S-values by tumor size and tissue composition is provided for application of the MIRD schema for tumor dosimetry in radiopharmaceutical therapy.
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Affiliation(s)
- Edmond Olguin
- J Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, Gainesville, FL 32611-6131, United States of America
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St James S, Bednarz B, Benedict S, Buchsbaum JC, Dewaraja Y, Frey E, Hobbs R, Grudzinski J, Roncali E, Sgouros G, Capala J, Xiao Y. Current Status of Radiopharmaceutical Therapy. Int J Radiat Oncol Biol Phys 2020; 109:891-901. [PMID: 32805300 DOI: 10.1016/j.ijrobp.2020.08.035] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2020] [Accepted: 08/06/2020] [Indexed: 02/02/2023]
Abstract
In radiopharmaceutical therapy (RPT), a radionuclide is systemically or locally delivered with the goal of targeting and delivering radiation to cancer cells while minimizing radiation exposure to untargeted cells. Examples of current RPTs include thyroid ablation with the administration of 131I, treatment of liver cancer with 90Y microspheres, the treatment of bony metastases with 223Ra, and the treatment of neuroendocrine tumors with 177Lu-DOTATATE. New RPTs are being developed where radionuclides are incorporated into systemic targeted therapies. To assure that RPT is appropriately implemented, advances in targeting need to be matched with advances in quantitative imaging and dosimetry methods. Currently, radiopharmaceutical therapy is administered by intravenous or locoregional injection, and the treatment planning has typically been implemented like chemotherapy, where the activity administered is either fixed or based on a patient's body weight or body surface area. RPT pharmacokinetics are measurable by quantitative imaging and are known to vary across patients, both in tumors and normal tissues. Therefore, fixed or weight-based activity prescriptions are not currently optimized to deliver a cytotoxic dose to targets while remaining within the tolerance dose of organs at risk. Methods that provide dose estimates to individual patients rather than to reference geometries are needed to assess and adjust the injected RPT dose. Accurate doses to targets and organs at risk will benefit the individual patients and decrease uncertainties in clinical trials. Imaging can be used to measure activity distribution in vivo, and this information can be used to determine patient-specific treatment plans where the dose to the targets and organs at risk can be calculated. The development and adoption of imaging-based dosimetry methods is particularly beneficial in early clinical trials. In this work we discuss dosimetric accuracy needs in modern radiation oncology, uncertainties in the dosimetry in RPT, and best approaches for imaging and dosimetry of internal radionuclide therapy.
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Affiliation(s)
- Sara St James
- Department of Radiation Oncology, University of California San Francisco, San Francisco, California.
| | - Bryan Bednarz
- Department of Medical Physics and Human Oncology, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin
| | - Stanley Benedict
- Department of Radiation Oncology, University of California Davis, Sacramento, California
| | - Jeffrey C Buchsbaum
- Radiation Research Program, Division of Cancer Treatment and Diagnosis, NCI, NIH, Bethesda, Maryland
| | - Yuni Dewaraja
- Department of Radiology, University of Michigan, Ann Arbor, Michigan
| | - Eric Frey
- Department of Radiology, Johns Hopkins University, Baltimore, Maryland
| | - Robert Hobbs
- Department of Radiology, Johns Hopkins University, Baltimore, Maryland
| | | | - Emilie Roncali
- Department of Radiation Oncology, University of California Davis, Sacramento, California
| | - George Sgouros
- Department of Radiology, Johns Hopkins University, Baltimore, Maryland
| | - Jacek Capala
- Radiation Research Program, Division of Cancer Treatment and Diagnosis, NCI, NIH, Bethesda, Maryland
| | - Ying Xiao
- Hospital of the University of Pennsylvania
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Tworowska I, Delpassand ES, Bolek L, Shanoon F, Sgouros G, Frey E, He B, Muzammil A, Ghaly M, Stallons T, Saidi A, Torgue J. Targeted Alpha-emitter Therapy of Neuroendocrine Tumors using 212Pb-octreotate (AlphaMedix TM). J Med Imaging Radiat Sci 2019. [DOI: 10.1016/j.jmir.2019.11.109] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Sgouros G, He B, Frey E, Berger M, Ludwig D. Impact of Target Cell Number on Target Cell and Tissue Dose for Antibody-Mediated Delivery of Alpha-Emitters. J Med Imaging Radiat Sci 2019. [DOI: 10.1016/j.jmir.2019.11.121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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16
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He B, Frey E, Sgouros G, Ghaly M, Tworowska I, Delpassand E. Development and Validation of Methods for Quantitative In Vivo SPECT of Pb-212. J Med Imaging Radiat Sci 2019. [DOI: 10.1016/j.jmir.2019.11.105] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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17
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Sgouros G, Frey E, He B, Ray N, Ludwig D. Dosimetric Impact of Ac-227 in Accelerator-Produced Ac-225. J Med Imaging Radiat Sci 2019. [DOI: 10.1016/j.jmir.2019.11.120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Cremer J, Melbinger A, Wienand K, Henriquez T, Jung H, Frey E. Cooperation in Microbial Populations: Theory and Experimental Model Systems. J Mol Biol 2019; 431:4599-4644. [PMID: 31634468 DOI: 10.1016/j.jmb.2019.09.023] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2019] [Revised: 09/25/2019] [Accepted: 09/26/2019] [Indexed: 01/07/2023]
Abstract
Cooperative behavior, the costly provision of benefits to others, is common across all domains of life. This review article discusses cooperative behavior in the microbial world, mediated by the exchange of extracellular products called public goods. We focus on model species for which the production of a public good and the related growth disadvantage for the producing cells are well described. To unveil the biological and ecological factors promoting the emergence and stability of cooperative traits we take an interdisciplinary perspective and review insights gained from both mathematical models and well-controlled experimental model systems. Ecologically, we include crucial aspects of the microbial life cycle into our analysis and particularly consider population structures where ensembles of local communities (subpopulations) continuously emerge, grow, and disappear again. Biologically, we explicitly consider the synthesis and regulation of public good production. The discussion of the theoretical approaches includes general evolutionary concepts, population dynamics, and evolutionary game theory. As a specific but generic biological example, we consider populations of Pseudomonas putida and its regulation and use of pyoverdines, iron scavenging molecules, as public goods. The review closes with an overview on cooperation in spatially extended systems and also provides a critical assessment of the insights gained from the experimental and theoretical studies discussed. Current challenges and important new research opportunities are discussed, including the biochemical regulation of public goods, more realistic ecological scenarios resembling native environments, cell-to-cell signaling, and multispecies communities.
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Affiliation(s)
- J Cremer
- Department of Molecular Immunology and Microbiology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, 9747 AG Groningen, the Netherlands
| | - A Melbinger
- Arnold-Sommerfeld-Center for Theoretical Physics and Center for Nanoscience, Ludwig-Maximilians-Universität München, Theresienstrasse 37, D-80333 Munich, Germany
| | - K Wienand
- Arnold-Sommerfeld-Center for Theoretical Physics and Center for Nanoscience, Ludwig-Maximilians-Universität München, Theresienstrasse 37, D-80333 Munich, Germany
| | - T Henriquez
- Microbiology, Department of Biology I, Ludwig-Maximilians-Universität München, Grosshaderner Strasse 2-4, Martinsried, Germany
| | - H Jung
- Microbiology, Department of Biology I, Ludwig-Maximilians-Universität München, Grosshaderner Strasse 2-4, Martinsried, Germany.
| | - E Frey
- Arnold-Sommerfeld-Center for Theoretical Physics and Center for Nanoscience, Ludwig-Maximilians-Universität München, Theresienstrasse 37, D-80333 Munich, Germany.
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Tworowska I, Stallons T, Delpassand E, Torgue J, Saidi A, Jurek P, Kiefer G, Rojas-Quijano F, Ghaly M, Frey E, Sgouros G. Theranostic 203/212Pb-labeled octreotate analogs (AlphaMedix TM) and their preclinical characterization for the Phase I clinical studies in neuroendocrine cancer patients. Nucl Med Biol 2019. [DOI: 10.1016/s0969-8051(19)30242-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Abstract
Dynamic patterning of specific proteins is essential for the spatio-temporal regulation of many important intracellular processes in prokaryotes, eukaryotes and multicellular organisms. The emergence of patterns generated by interactions of diffusing proteins is a paradigmatic example for self-organization. In this article, we review quantitative models for intracellular Min protein patterns in Escherichia coli, Cdc42 polarization in Saccharomyces cerevisiae and the bipolar PAR protein patterns found in Caenorhabditis elegans. By analysing the molecular processes driving these systems we derive a theoretical perspective on general principles underlying self-organized pattern formation. We argue that intracellular pattern formation is not captured by concepts such as ‘activators’, ‘inhibitors’ or ‘substrate depletion’. Instead, intracellular pattern formation is based on the redistribution of proteins by cytosolic diffusion, and the cycling of proteins between distinct conformational states. Therefore, mass-conserving reaction–diffusion equations provide the most appropriate framework to study intracellular pattern formation. We conclude that directed transport, e.g. cytosolic diffusion along an actively maintained cytosolic gradient, is the key process underlying pattern formation. Thus the basic principle of self-organization is the establishment and maintenance of directed transport by intracellular protein dynamics. This article is part of the theme issue ‘Self-organization in cell biology’.
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Affiliation(s)
- J Halatek
- Arnold Sommerfeld Center for Theoretical Physics and Center for NanoScience, Department of Physics, Ludwig-Maximilians-Universität München, Theresienstraße 37, D-80333 München, Germany
| | - F Brauns
- Arnold Sommerfeld Center for Theoretical Physics and Center for NanoScience, Department of Physics, Ludwig-Maximilians-Universität München, Theresienstraße 37, D-80333 München, Germany
| | - E Frey
- Arnold Sommerfeld Center for Theoretical Physics and Center for NanoScience, Department of Physics, Ludwig-Maximilians-Universität München, Theresienstraße 37, D-80333 München, Germany
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He B, Frey E, Sgouros G, Ghaly M, Tworowska I, Delpassand E. Development and Validation of Methods for Quantitative In Vivo SPECT of Pb-212. J Med Imaging Radiat Sci 2019. [DOI: 10.1016/j.jmir.2019.03.100] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Karimi Ghodoosi E, D'Alessandria C, Li Y, Bartel A, Köhner M, Höllriegl V, Navab N, Eiber M, Li WB, Frey E, Ziegler S. The effect of attenuation map, scatter energy window width, and volume of interest on the calibration factor calculation in quantitative 177Lu SPECT imaging: Simulation and phantom study. Phys Med 2018; 56:74-80. [DOI: 10.1016/j.ejmp.2018.11.009] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/07/2018] [Revised: 11/07/2018] [Accepted: 11/15/2018] [Indexed: 10/27/2022] Open
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Huber L, Suzuki R, Krüger T, Frey E, Bausch AR. Emergence of coexisting ordered states in active matter systems. Science 2018; 361:255-258. [DOI: 10.1126/science.aao5434] [Citation(s) in RCA: 75] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2017] [Revised: 01/22/2018] [Accepted: 05/16/2018] [Indexed: 01/16/2023]
Abstract
Active systems can produce a far greater variety of ordered patterns than conventional equilibrium systems. In particular, transitions between disorder and either polar- or nematically ordered phases have been predicted and observed in two-dimensional active systems. However, coexistence between phases of different types of order has not been reported. We demonstrate the emergence of dynamic coexistence of ordered states with fluctuating nematic and polar symmetry in an actomyosin motility assay. Combining experiments with agent-based simulations, we identify sufficiently weak interactions that lack a clear alignment symmetry as a prerequisite for coexistence. Thus, the symmetry of macroscopic order becomes an emergent and dynamic property of the active system. These results provide a pathway by which living systems can express different types of order by using identical building blocks.
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Affiliation(s)
- L. Huber
- Arnold Sommerfeld Center for Theoretical Physics and Center for NanoScience, Department of Physics, Ludwig-Maximilians-Universität München, D-80333 Munich, Theresienstrasse 37, Germany
| | - R. Suzuki
- Lehrstuhl für Biophysik (E27), Technische Universität München, James-Franck-Strasse 1, D-85748 Garching, Germany
- Graduate School of Medicine, Kyoto University, 606-8501 Kyoto, Japan
- Institute for Integrated Cell-Material Sciences, Kyoto University, 606-8501 Kyoto, Japan
| | - T. Krüger
- Arnold Sommerfeld Center for Theoretical Physics and Center for NanoScience, Department of Physics, Ludwig-Maximilians-Universität München, D-80333 Munich, Theresienstrasse 37, Germany
| | - E. Frey
- Arnold Sommerfeld Center for Theoretical Physics and Center for NanoScience, Department of Physics, Ludwig-Maximilians-Universität München, D-80333 Munich, Theresienstrasse 37, Germany
| | - A. R. Bausch
- Lehrstuhl für Biophysik (E27), Technische Universität München, James-Franck-Strasse 1, D-85748 Garching, Germany
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Jha AK, Mena E, Caffo B, Ashrafinia S, Rahmim A, Frey E, Subramaniam RM. Practical no-gold-standard evaluation framework for quantitative imaging methods: application to lesion segmentation in positron emission tomography. J Med Imaging (Bellingham) 2017; 4:011011. [PMID: 28331883 DOI: 10.1117/1.jmi.4.1.011011] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2016] [Accepted: 02/09/2017] [Indexed: 11/14/2022] Open
Abstract
Recently, a class of no-gold-standard (NGS) techniques have been proposed to evaluate quantitative imaging methods using patient data. These techniques provide figures of merit (FoMs) quantifying the precision of the estimated quantitative value without requiring repeated measurements and without requiring a gold standard. However, applying these techniques to patient data presents several practical difficulties including assessing the underlying assumptions, accounting for patient-sampling-related uncertainty, and assessing the reliability of the estimated FoMs. To address these issues, we propose statistical tests that provide confidence in the underlying assumptions and in the reliability of the estimated FoMs. Furthermore, the NGS technique is integrated within a bootstrap-based methodology to account for patient-sampling-related uncertainty. The developed NGS framework was applied to evaluate four methods for segmenting lesions from F-Fluoro-2-deoxyglucose positron emission tomography images of patients with head-and-neck cancer on the task of precisely measuring the metabolic tumor volume. The NGS technique consistently predicted the same segmentation method as the most precise method. The proposed framework provided confidence in these results, even when gold-standard data were not available. The bootstrap-based methodology indicated improved performance of the NGS technique with larger numbers of patient studies, as was expected, and yielded consistent results as long as data from more than 80 lesions were available for the analysis.
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Affiliation(s)
- Abhinav K Jha
- Johns Hopkins University , Department of Radiology and Radiological Sciences, Baltimore, Maryland, United States
| | - Esther Mena
- Johns Hopkins University , Department of Radiology and Radiological Sciences, Baltimore, Maryland, United States
| | - Brian Caffo
- Johns Hopkins University , Department of Biostatistics, Baltimore, Maryland, United States
| | - Saeed Ashrafinia
- Johns Hopkins University, Department of Radiology and Radiological Sciences, Baltimore, Maryland, United States; Johns Hopkins University, Department of Electrical & Computer Engineering, Baltimore, Maryland, United States
| | - Arman Rahmim
- Johns Hopkins University, Department of Radiology and Radiological Sciences, Baltimore, Maryland, United States; Johns Hopkins University, Department of Electrical & Computer Engineering, Baltimore, Maryland, United States
| | - Eric Frey
- Johns Hopkins University, Department of Radiology and Radiological Sciences, Baltimore, Maryland, United States; Johns Hopkins University, Department of Electrical & Computer Engineering, Baltimore, Maryland, United States
| | - Rathan M Subramaniam
- University of Texas Southwestern Medical Center , Department of Radiology and Advanced Imaging Research Center, Dallas, Texas, United States
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Abstract
Several new and improved modalities, scanners, and protocols, together referred to as image-acquisition methods (IAMs), are being developed to provide reliable quantitative imaging. Objective evaluation of these IAMs on the clinically relevant quantitative tasks is highly desirable. Such evaluation is most reliable and clinically decisive when performed with patient data, but that requires the availability of a gold standard, which is often rare. While no-gold-standard (NGS) techniques have been developed to clinically evaluate quantitative imaging methods, these techniques require that each of the patients be scanned using all the IAMs, which is expensive, time consuming, and could lead to increased radiation dose. A more clinically practical scenario is where different set of patients are scanned using different IAMs. We have developed an NGS technique that uses patient data where different patient sets are imaged using different IAMs to compare the different IAMs. The technique posits a linear relationship, characterized by a slope, bias, and noise standard-deviation term, between the true and measured quantitative values. Under the assumption that the true quantitative values have been sampled from a unimodal distribution, a maximum-likelihood procedure was developed that estimates these linear relationship parameters for the different IAMs. Figures of merit can be estimated using these linear relationship parameters to evaluate the IAMs on the basis of accuracy, precision, and overall reliability. The proposed technique has several potential applications such as in protocol optimization, quantifying difference in system performance, and system harmonization using patient data.
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Affiliation(s)
- Abhinav K Jha
- Department of Radiology, Johns Hopkins University, Baltimore, MD USA
| | - Eric Frey
- Department of Radiology, Johns Hopkins University, Baltimore, MD USA
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Frey E, Walls D. Book ReviewGrowing Green Families: A Guide for Natural Families and Healthy Homes. Clin Lactation 2017. [DOI: 10.1891/2158-0782.8.4.198] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Hobbs RF, Josefsson A, Mauxion T, Frey E, Plyku D, Meyer C, Terezakis S, Sgouros G, Loeb D. Preliminary Results from a Combined 153Sm-EDTMP and External Beam Radiation Therapy for Metastatic Osteosarcoma Patients Using Prospective Absorbed Dose-Based Treatment Planning. Brachytherapy 2016. [DOI: 10.1016/j.brachy.2016.04.232] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Tscholl PM, Zingg PO, Dora C, Frey E, Dierauer S, Ramseier LE. Arthroscopic osteochondroplasty in patients with mild slipped capital femoral epiphysis after in situ fixation. J Child Orthop 2016; 10:25-30. [PMID: 26586587 PMCID: PMC4763150 DOI: 10.1007/s11832-015-0707-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/28/2015] [Accepted: 11/06/2015] [Indexed: 02/03/2023] Open
Abstract
PURPOSE Mild slipped capital femoral epiphyses (SCFE) nevertheless show significant femoral head-neck deformities which may put cartilage and acetabular labrum at risk. Whether this deformity can be restored to normal has not yet been described in the literature. METHODS In a prospective follow-up study, 14 patients with mild SCFE underwent in situ fixation with a single 6.5-mm cancellous, partially threaded screw. In 14 patients arthroscopic osteochondroplasty was performed, and in 13 patients pre- and postoperative measurements of the α-angle were made using antero-superior radial magnetic resonance imaging. RESULTS After arthroscopic osteochondroplasty, the mean α-angle decreased from 57° (range 50°-74°) to 37° (range 32°-47°; p < 0.001). Six patients showed beginning degenerative intra-articular changes (four antero-superior cartilage and three antero-superior labrum lesions) at the time of hip arthroscopy. No intra-operative complications occurred. In one patient, arthroscopic debridement was necessary due to arthrofibrosis and persistent pain. CONCLUSION Arthroscopic osteochondroplasty can successfully correct the antero-superior α-angle in patients with mild SCFE to normal values. Clinical randomized controlled studies with long-term follow-up are required to find evidence of improved functional and radiographic mid- and long-term outcome compared to in situ fixation alone.
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Affiliation(s)
- Philippe M. Tscholl
- Department of Orthopaedics, Balgrist University Hospital, University of Zurich, Forchstrasse 340, 8008 Zurich, Switzerland
| | - Patrick O. Zingg
- Department of Orthopaedics, Balgrist University Hospital, University of Zurich, Forchstrasse 340, 8008 Zurich, Switzerland
| | - Claudio Dora
- Department of Orthopaedics, Balgrist University Hospital, University of Zurich, Forchstrasse 340, 8008 Zurich, Switzerland
| | - Eric Frey
- Department of Orthopaedics, Balgrist University Hospital, University of Zurich, Forchstrasse 340, 8008 Zurich, Switzerland
| | - Stefan Dierauer
- Orthopaedic Division, Department of Surgery, University Children’s Hospital, University Hospital of Zurich, Zurich, Switzerland
| | - Leonhard E. Ramseier
- Orthopaedic Division, Department of Surgery, University Children’s Hospital, University Hospital of Zurich, Zurich, Switzerland
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Ghaly M, Links JM, Frey E. Optimization of energy window and evaluation of scatter compensation methods in myocardial perfusion SPECT using the ideal observer with and without model mismatch and an anthropomorphic model observer. J Med Imaging (Bellingham) 2015; 2:015502. [PMID: 26029730 PMCID: PMC4447606 DOI: 10.1117/1.jmi.2.1.015502] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2014] [Accepted: 02/03/2015] [Indexed: 11/14/2022] Open
Abstract
We used the ideal observer (IO) and IO with model mismatch (IO-MM) applied in the projection domain and an anthropomorphic channelized Hotelling observer (CHO) applied to reconstructed images to optimize the acquisition energy window width and to evaluate various scatter compensation methods in the context of a myocardial perfusion single-photon emission computed tomography (SPECT) defect detection task. The IO has perfect knowledge of the image formation process and thus reflects the performance with perfect compensation for image-degrading factors. Thus, using the IO to optimize imaging systems could lead to suboptimal parameters compared with those optimized for humans interpreting SPECT images reconstructed with imperfect or no compensation. The IO-MM allows incorporating imperfect system models into the IO optimization process. We found that with near-perfect scatter compensation, the optimal energy window for the IO and CHO was similar; in its absence, the IO-MM gave a better prediction of the optimal energy window for the CHO using different scatter compensation methods. These data suggest that the IO-MM may be useful for projectiondomain optimization when MM is significant and that the IO is useful when followed by reconstruction with good models of the image formation process.
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Affiliation(s)
- Michael Ghaly
- Johns Hopkins University, The Russell H. Morgan Department of Radiology and Radiological Science, Baltimore, Maryland, United States
| | - Jonathan M. Links
- Johns Hopkins University, Department of Environmental Health Sciences, Baltimore, Maryland, United States
| | - Eric Frey
- Johns Hopkins University, The Russell H. Morgan Department of Radiology and Radiological Science, Baltimore, Maryland, United States
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Frey E, Valakh V, Karney-Grobe S, Shi Y, Milbrandt J, DiAntonio A. An in vitro assay to study induction of the regenerative state in sensory neurons. Exp Neurol 2014; 263:350-63. [PMID: 25447942 DOI: 10.1016/j.expneurol.2014.10.012] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2014] [Revised: 10/14/2014] [Accepted: 10/18/2014] [Indexed: 10/24/2022]
Abstract
After injury, peripheral neurons activate a pro-regenerative program that facilitates axon regeneration. While many regeneration-associated genes have been identified, the mechanism by which injury activates this program is less well understood. Furthermore, identifying pharmacological methods to induce a pro-regenerative state could lead to novel treatments to repair the injured nervous system. Therefore, we have developed an in vitro assay to study induction of the pro-regenerative state following injury or pharmacological treatment. First, we took advantage of the observation that dissociating and culturing sensory neurons from dorsal root ganglia activates a pro-regenerative program. We show that cultured neurons activate transcription factors and upregulate regeneration-associated genes common to the pro-regenerative program within the first hours after dissection. In a paradigm similar to pre-conditioning, neurons injured by dissociation display enhanced neurite outgrowth when replated as early as 12h after being removed from the animal. Furthermore, stimulation of the pro-regenerative state improves growth on inhibitory substrates and requires DLK/JNK signaling, both hallmarks of the pro-regeneration response in vivo. Finally, we modified this assay in order to identify new methods to activate the pro-regenerative state in an effort to mimic the pre-conditioning effect. We report that after several days in culture, neurons down-regulate many molecular hallmarks of injury and no longer display enhanced neurite outgrowth after replating. Hence, these neurons are functionally naïve and are a useful tool for identifying methods to induce the pro-regenerative state. We show that both injury and pre-treatment with forskolin reactivate the pro-regenerative state in this paradigm. Hence, this assay is useful for identifying pharmacological agents that induce the pro-regenerative state in the absence of injury.
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Affiliation(s)
- E Frey
- Department of Developmental Biology, Hope Center for Neurological Disorders, Washington University School of Medicine, St. Louis, MO 63110, USA.
| | - V Valakh
- Department of Developmental Biology, Hope Center for Neurological Disorders, Washington University School of Medicine, St. Louis, MO 63110, USA.
| | - S Karney-Grobe
- Department of Developmental Biology, Hope Center for Neurological Disorders, Washington University School of Medicine, St. Louis, MO 63110, USA.
| | - Y Shi
- Department of Developmental Biology, Hope Center for Neurological Disorders, Washington University School of Medicine, St. Louis, MO 63110, USA.
| | - J Milbrandt
- Department of Genetics, Hope Center for Neurological Disorders, Washington University School of Medicine, St. Louis, MO 63110, USA.
| | - A DiAntonio
- Department of Developmental Biology, Hope Center for Neurological Disorders, Washington University School of Medicine, St. Louis, MO 63110, USA.
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Ghaly M, Du Y, Fung GSK, Tsui BMW, Links JM, Frey E. Design of a digital phantom population for myocardial perfusion SPECT imaging research. Phys Med Biol 2014; 59:2935-53. [PMID: 24841729 DOI: 10.1088/0031-9155/59/12/2935] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Digital phantoms and Monte Carlo (MC) simulations have become important tools for optimizing and evaluating instrumentation, acquisition and processing methods for myocardial perfusion SPECT (MPS). In this work, we designed a new adult digital phantom population and generated corresponding Tc-99m and Tl-201 projections for use in MPS research. The population is based on the three-dimensional XCAT phantom with organ parameters sampled from the Emory PET Torso Model Database. Phantoms included three variations each in body size, heart size, and subcutaneous adipose tissue level, for a total of 27 phantoms of each gender. The SimSET MC code and angular response functions were used to model interactions in the body and the collimator-detector system, respectively. We divided each phantom into seven organs, each simulated separately, allowing use of post-simulation summing to efficiently model uptake variations. Also, we adapted and used a criterion based on the relative Poisson effective count level to determine the required number of simulated photons for each simulated organ. This technique provided a quantitative estimate of the true noise in the simulated projection data, including residual MC simulation noise. Projections were generated in 1 keV wide energy windows from 48-184 keV assuming perfect energy resolution to permit study of the effects of window width, energy resolution, and crosstalk in the context of dual isotope MPS. We have developed a comprehensive method for efficiently simulating realistic projections for a realistic population of phantoms in the context of MPS imaging. The new phantom population and realistic database of simulated projections will be useful in performing mathematical and human observer studies to evaluate various acquisition and processing methods such as optimizing the energy window width, investigating the effect of energy resolution on image quality and evaluating compensation methods for degrading factors such as crosstalk in the context of single and dual isotope MPS.
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Affiliation(s)
- Michael Ghaly
- The Russell H Morgan Department of Radiology and Radiological Science, Johns Hopkins University, Baltimore, MD, USA
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Weber CA, Hanke T, Deseigne J, Léonard S, Dauchot O, Frey E, Chaté H. Long-range ordering of vibrated polar disks. Phys Rev Lett 2013; 110:208001. [PMID: 25167452 DOI: 10.1103/physrevlett.110.208001] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/31/2012] [Indexed: 06/03/2023]
Abstract
Vibrated polar disks have been used experimentally to investigate collective motion of driven particles, where fully ordered asymptotic regimes could not be reached. Here we present a model reproducing quantitatively the single, binary, and collective properties of this granular system. Using system sizes not accessible in the laboratory, we show in silico that true long-range order is possible in the experimental system. Exploring the model's parameter space, we find a phase diagram qualitatively different from that of dilute or pointlike particle systems.
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Affiliation(s)
- C A Weber
- Arnold Sommerfeld Center for Theoretical Physics and Center for NanoScience, Department of Physics, Ludwig-Maximilians-Universität München, 80333 Munich, Germany
| | - T Hanke
- Arnold Sommerfeld Center for Theoretical Physics and Center for NanoScience, Department of Physics, Ludwig-Maximilians-Universität München, 80333 Munich, Germany
| | - J Deseigne
- Laboratoire de Physique, ENS de Lyon and CNRS UMR 5672, 69007 Lyon, France
| | - S Léonard
- Service de Physique de l'Etat Condensé, CEA-Saclay and CNRS URA 2464, 91191 Gif-sur-Yvette, France
| | - O Dauchot
- Service de Physique de l'Etat Condensé, CEA-Saclay and CNRS URA 2464, 91191 Gif-sur-Yvette, France and EC2M-Gulliver, ESPCI-ParisTech and CNRS UMR 7083, 75005 Paris, France
| | - E Frey
- Arnold Sommerfeld Center for Theoretical Physics and Center for NanoScience, Department of Physics, Ludwig-Maximilians-Universität München, 80333 Munich, Germany
| | - H Chaté
- Service de Physique de l'Etat Condensé, CEA-Saclay and CNRS URA 2464, 91191 Gif-sur-Yvette, France and Max Planck Institute for the Physics of Complex Systems, Nöthnitzer Straße 38, 01187 Dresden, Germany
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Wayson M, Lee C, Sgouros G, Treves ST, Frey E, Bolch WE. Internal photon and electron dosimetry of the newborn patient--a hybrid computational phantom study. Phys Med Biol 2012; 57:1433-57. [PMID: 22354044 DOI: 10.1088/0031-9155/57/5/1433] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Estimates of radiation absorbed dose to organs of the nuclear medicine patient are a requirement for administered activity optimization and for stochastic risk assessment. Pediatric patients, and in particular the newborn child, represent that portion of the patient population where such optimization studies are most crucial owing to the enhanced tissue radiosensitivities and longer life expectancies of this patient subpopulation. In cases where whole-body CT imaging is not available, phantom-based calculations of radionuclide S values--absorbed dose to a target tissue per nuclear transformation in a source tissue--are required for dose and risk evaluation. In this study, a comprehensive model of electron and photon dosimetry of the reference newborn child is presented based on a high-resolution hybrid-voxel phantom from the University of Florida (UF) patient model series. Values of photon specific absorbed fraction (SAF) were assembled for both the reference male and female newborn using the radiation transport code MCNPX v2.6. Values of electron SAF were assembled in a unique and time-efficient manner whereby the collisional and radiative components of organ dose--for both self- and cross-dose terms--were computed separately. Dose to the newborn skeletal tissues were assessed via fluence-to-dose response functions reported for the first time in this study. Values of photon and electron SAFs were used to assemble a complete set of S values for some 16 radionuclides commonly associated with molecular imaging of the newborn. These values were then compared to those available in the OLINDA/EXM software. S value ratios for organ self-dose ranged from 0.46 to 1.42, while similar ratios for organ cross-dose varied from a low of 0.04 to a high of 3.49. These large discrepancies are due in large part to the simplistic organ modeling in the stylized newborn model used in the OLINDA/EXM software. A comprehensive model of internal dosimetry is presented in this study for the newborn nuclear medicine patient based upon the UF hybrid computational phantom. Photon dose response functions, photon and electron SAFs, and tables of radionuclide S values for the newborn child--both male and female--are given in a series of four electronic annexes available at stacks.iop.org/pmb/57/1433/mmedia. These values can be applied to optimization studies of image quality and stochastic risk for this most vulnerable class of pediatric patients.
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Affiliation(s)
- Michael Wayson
- J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, Gainesville, FL 32611, USA.
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Zumstein MA, Frey E, von Rechenberg B, Frigg R, Gerber C, Meyer DC. Device for lengthening of a musculotendinous unit by direct continuous traction in the sheep. BMC Vet Res 2012; 8:50. [PMID: 22551079 PMCID: PMC3462135 DOI: 10.1186/1746-6148-8-50] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2011] [Accepted: 04/18/2012] [Indexed: 11/10/2022] Open
Abstract
Background Retraction, atrophy and fatty infiltration are signs subsequent to chronic rotator cuff tendon tears. They are associated with an increased pennation angle and a shortening of the muscle fibers in series. These deleterious changes of the muscular architecture are not reversible with current repair techniques and are the main factors for failed rotator cuff tendon repair. Whereas fast stretching of the retracted musculotendinous unit results in proliferation of non-contractile fibrous tissue, slow stretching may lead to muscle regeneration in terms of sarcomerogenesis. To slowly stretch the retracted musculotendinous unit in a sheep model, two here described tensioning devices have been developed and mounted on the scapular spine of the sheep using an expandable threaded rod, which has been interposed between the retracted tendon end and the original insertion site at the humeral head. Traction is transmitted in line with the musculotendinous unit by sutures knotted on the expandable threaded rod. The threaded rod of the tensioner is driven within the body through a rotating axis, which enters the body on the opposite side. The tendon end, which was previously released (16 weeks prior) from its insertion site with a bone chip, was elongated with a velocity of 1 mm/day. Results After several steps of technical improvements, the tensioner proved to be capable of actively stretching the retracted and degenerated muscle back to the original length and to withstand the external forces acting on it. Conclusion This technical report describes the experimental technique for continuous elongation of the musculotendinous unit and reversion of the length of chronically shortened muscle.
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Affiliation(s)
- Matthias A Zumstein
- Dept. of Orthopedics, University of Zurich, Balgrist, Zürich, 8008, Switzerland
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Gruber I, Frey E. Erworbenes Horner-Syndrom bei einem Säugling. Klin Monbl Augenheilkd 2012; 229:162-3. [DOI: 10.1055/s-0031-1273234] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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Frey E. 22 INVITED Transition From Paediatric to Adult Care – Models of Care. Eur J Cancer 2011. [DOI: 10.1016/s0959-8049(11)70237-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Frey E. WE-E-214-01: Targeted Radionuclide Therapy. Med Phys 2011. [DOI: 10.1118/1.3613390] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Hayden R, Sawyer S, Frey E, Mori S, Migliaccio AA, Della Santina CC. Erratum to: Virtual labyrinth model of vestibular afferent excitation via implanted electrodes: validation and application to design of a multichannel vestibular prosthesis. Exp Brain Res 2011. [DOI: 10.1007/s00221-011-2640-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Alim K, Frey E. Quantitative predictions on auxin-induced polar distribution of PIN proteins during vein formation in leaves. Eur Phys J E Soft Matter 2010; 33:165-173. [PMID: 20571847 DOI: 10.1140/epje/i2010-10604-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2009] [Accepted: 05/10/2010] [Indexed: 05/29/2023]
Abstract
The dynamic patterning of the plant hormone auxin and its efflux facilitator the PIN protein are the key regulators for the spatial and temporal organization of plant development. In particular auxin induces the polar localization of its own efflux facilitator. Due to this positive feedback, auxin flow is directed and patterns of auxin and PIN arise. During the earliest stage of vein initiation in leaves auxin accumulates in a single cell in a rim of epidermal cells from which it flows into the ground meristem tissue of the leaf blade. There the localized auxin supply yields the successive polarization of PIN distribution along a strand of cells. We model the auxin and PIN dynamics within cells with a minimal canalization model. Solving the model analytically we uncover an excitable polarization front that triggers a polar distribution of PIN proteins in cells. As polarization fronts may extend to opposing directions from their initiation site, we suggest a possible resolution to the puzzling occurrence of bipolar cells, thus we offer an explanation for the development of closed, looped veins. Employing non-linear analysis, we identify the role of the contributing microscopic processes during polarization. Furthermore, we deduce quantitative predictions on polarization fronts establishing a route to determine the up to now largely unknown kinetic rates of auxin and PIN dynamics.
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Affiliation(s)
- K Alim
- Arnold Sommerfeld Center for Theoretical Physics and Center for NanoScience, Ludwig-Maximilians-Universität, Theresienstr. 37, D-80333, München, Germany.
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Rohr C, Balbás Gambra M, Gruber K, Constable EC, Frey E, Franosch T, Hermann BA. Molecular jigsaw: pattern diversity encoded by elementary geometrical features. Nano Lett 2010; 10:833-837. [PMID: 20158248 DOI: 10.1021/nl903225j] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Scanning tunneling microscopy (STM) images of self-organized monolayers of Frechet dendrons display a variety of two-dimensional ordering motifs, which are influenced by engineering the molecular interactions. An interaction-site model condenses the essential molecular properties determined by molecular mechanics modeling, which in a Monte Carlo approach successfully predicts the various ordering motifs. This confirms that geometry as well as a few salient weak interaction sites encode these structural motifs.
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Affiliation(s)
- C Rohr
- Center for NanoScience (CeNS) and Walther-Meissner-Institute of Low Temperature Research of the Bavarian Academy of Sciences and Humanities, Walther-Meissner-Strasse 8, 85748 Garching, Germany
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Frey E. Pseudotumoröse proliferativ-ulzeröse Refluxösophagitis bei gleitender Hiatushernie. ROFO-FORTSCHR RONTG 2009. [DOI: 10.1055/s-0029-1227101] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Frey E. Tumordiagnostik des Mediastinums durch frontale Schrägtomographie. ROFO-FORTSCHR RONTG 2009. [DOI: 10.1055/s-0029-1227091] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Stöhr W, Langer T, Kremers A, Bielack S, Lamprecht-Dinnesen A, Frey E, Beck JD. Cisplatin-Induced Ototoxicity in Osteosarcoma Patients: A Report from the Late Effects Surveillance System. Cancer Invest 2009; 23:201-7. [PMID: 15945505 DOI: 10.1081/cnv-200055951] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
The aim of this study was to analyze cisplatin-induced ototoxicity in a recent study trial. Seventy-four patients who had received cisplatin for the treatment of osteosarcoma (median cumulative dose: 360 mg/m2) were investigated prospectively for ototoxicity in a multicenter trial. Hearing function was tested by audiometry. We evaluated the incidence and dependencies of hearing loss. After cessation of therapy, 51% of the patients showed a hearing loss of >20 dB in the frequency range of 4-8 kHz. Only in one patient a hearing loss was found at 2 kHz, and in none at 1 kHz. At a cumulative cisplatin dose of < or = 240 mg/m2, almost no ototoxicity was found. Incidence and magnitude of hearing loss increased significantly with a higher cumulative dose. Furthermore, hearing thresholds were significantly poorer in children <12 years. A further follow-up investigation showed only a marginal change in hearing function. We conclude that ototoxicity is moderate in our group of patients and probably irreversible.
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Affiliation(s)
- W Stöhr
- Department of Pediatric Oncology, LESS Center, University Hospital for Children and Adolescents, Erlangen, Germany
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Frey E. Experimenteller Beitrag zur interstitiellen Therapie mit Yttrium 90-rods. Oncology 2009. [DOI: 10.1159/000224029] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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