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Almqvist H, Crotty D, Nyren S, Yu J, Arnberg-Sandor F, Brismar T, Tovatt C, Linder H, Dagotto J, Fredenberg E, Tamm MY, Deak P, Fanariotis M, Bujila R, Holmin S. Initial Clinical Images From a Second-Generation Prototype Silicon-Based Photon-Counting Computed Tomography System. Acad Radiol 2024; 31:572-581. [PMID: 37563023 DOI: 10.1016/j.acra.2023.06.031] [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: 03/31/2023] [Revised: 06/23/2023] [Accepted: 06/28/2023] [Indexed: 08/12/2023]
Abstract
RATIONALE AND OBJECTIVES To demonstrate the feasibility and potential of using a second-generation prototype photon-counting computed tomography (CT) system to provide simultaneous high spatial resolution images and high spectral resolution material information across a range of routine imaging tasks using clinical patient exposure levels. MATERIALS AND METHODS The photon-counting system employs an innovative silicon-based photon-counting detector to provide a balanced approach to ultra-high-resolution spectral CT imaging. An initial cohort of volunteer subjects was imaged using the prototype photon-counting system. Acquisition technique parameters and radiation dose exposures were guided by routine clinical exposure levels used at the institution. Images were reconstructed in native slice thickness using an early version of a spectral CT reconstruction algorithm Samples of images across a range of clinical tasks were selected and presented for review. RESULTS Clinical cases are presented across inner ear, carotid angiography, chest, and musculoskeletal imaging tasks. Initial reconstructed images illustrate ultra-high spatial resolution imaging. The fine detail of small structures and pathologies is clearly visualized, and structural boundaries are well delineated. The prototype system additionally provides concomitant spectral information with high spatial resolution. CONCLUSION This initial study demonstrates that routine imaging at clinically appropriate patient exposure levels is feasible using a novel deep-silicon photon-counting detector CT system. Furthermore, a deep-silicon detector may provide a balanced approach to photon-counting CT, providing high spatial resolution imaging with simultaneous high-fidelity spectral information.
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Affiliation(s)
- Hakan Almqvist
- Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden (H.A., F.A.-S., S.H.); Department of Radiology, Capio St Göran Hospital, Stockholm, Sweden (H.A.)
| | | | - Sven Nyren
- Department of Thoraxradiology, Karolinska University Hospital, Stockholm, Sweden (S.N., J.Y.); Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden (S.N., J.Y.)
| | - Jimmy Yu
- Department of Thoraxradiology, Karolinska University Hospital, Stockholm, Sweden (S.N., J.Y.); Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden (S.N., J.Y.)
| | - Fabian Arnberg-Sandor
- Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden (H.A., F.A.-S., S.H.); Department of Neuroradiology, Karolinska University Hospital, Stockholm, Sweden (F.A.-S., S.H.)
| | - Torkel Brismar
- Department of Clinical Sciences, Intervention and Technology, Karolinska Institutet, Stockholm, Sweden (T.B.); Department of Radiology, Medical Diagnostics Karolinska, Karolinska University Hospital, Stockholm, Sweden (T.B.)
| | - Cedric Tovatt
- GE HealthCare, Stockholm, Sweden (C.T., H.L., J.D., E.F., M.Y.T.)
| | - Hugo Linder
- GE HealthCare, Stockholm, Sweden (C.T., H.L., J.D., E.F., M.Y.T.)
| | - Jose Dagotto
- GE HealthCare, Stockholm, Sweden (C.T., H.L., J.D., E.F., M.Y.T.)
| | - Erik Fredenberg
- GE HealthCare, Stockholm, Sweden (C.T., H.L., J.D., E.F., M.Y.T.)
| | - Moa Yveborg Tamm
- GE HealthCare, Stockholm, Sweden (C.T., H.L., J.D., E.F., M.Y.T.)
| | - Paul Deak
- GE HealthCare, Zurich, Switzerland (P.D.)
| | | | | | - Staffan Holmin
- Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden (H.A., F.A.-S., S.H.); Department of Neuroradiology, Karolinska University Hospital, Stockholm, Sweden (F.A.-S., S.H.)
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Giannopoulos AA, Keller L, Sepulcri D, Boehm R, Garefa C, Venugopal P, Mitra J, Ghose S, Deak P, Pack JD, Davis CL, Stähli BE, Stehli J, Pazhenkottil AP, Kaufmann PA, Buechel RR. High-Speed On-Site Deep Learning-Based FFR-CT Algorithm: Evaluation Using Invasive Angiography as the Reference Standard. AJR Am J Roentgenol 2023; 221:460-470. [PMID: 37132550 DOI: 10.2214/ajr.23.29156] [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] [Indexed: 05/04/2023]
Abstract
BACKGROUND. Estimation of fractional flow reserve from coronary CTA (FFR-CT) is an established method of assessing the hemodynamic significance of coronary lesions. However, clinical implementation has progressed slowly, partly because of off-site data transfer with long turnaround times for results. OBJECTIVE. The purpose of this study was to evaluate the diagnostic performance of FFR-CT computed on-site with a high-speed deep learning-based algorithm with invasive hemodynamic indexes as the reference standard. METHODS. This retrospective study included 59 patients (46 men, 13 women; mean age, 66.5 ± 10.2 years) who underwent coronary CTA (including calcium scoring) followed within 90 days by invasive angiography with invasive fractional flow reserve (FFR) and/or instantaneous wave-free ratio measurements from December 2014 to October 2021. Coronary artery lesions were considered to have hemodynamically significant stenosis in the presence of invasive FFR of 0.80 or less and/or instantaneous wave-free ratio of 0.89 or less. A single cardiologist evaluated the CTA images using an on-site deep learning-based semiautomated algorithm entailing a 3D computational flow dynamics model to determine FFR-CT for coronary artery lesions detected with invasive angiography. Time for FFR-CT analysis was recorded. FFR-CT analysis was repeated by the same cardiologist in 26 randomly selected examinations and by a different cardiologist in 45 randomly selected examinations. Diagnostic performance and agreement were assessed. RESULTS. A total of 74 lesions were identified with invasive angiography. FFR-CT and invasive FFR had strong correlation (r = 0.81) and, in Bland-Altman analysis, bias of 0.01 and 95% limits of agreement of -0.13 to 0.15. FFR-CT had AUC for hemodynamically significant stenosis of 0.975. At a cutoff of 0.80 or less, FFR-CT had 95.9% accuracy, 93.5% sensitivity, and 97.7% specificity. In 39 lesions with severe calcifications (≥ 400 Agatston units), FFR-CT had AUC of 0.991 and at a cutoff of 0.80, 94.7% sensitivity, 95.0% specificity, and 94.9% accuracy. Mean analysis time per patient was 7 minutes 54 seconds. Intraobserver agreement (intraclass correlation coefficient, 0.85; bias, -0.01; 95% limits of agreement, -0.12 and 0.10) and interobserver agreement (intraclass correlation coefficient, 0.94; bias, -0.01; 95% limits of agreement, -0.08 and 0.07) were good to excellent. CONCLUSION. A high-speed on-site deep learning-based FFR-CT algorithm had excellent diagnostic performance for hemodynamically significant stenosis with high reproducibility. CLINICAL IMPACT. The algorithm should facilitate implementation of FFR-CT technology into routine clinical practice.
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Affiliation(s)
- Andreas A Giannopoulos
- Department of Nuclear Medicine, Cardiac Imaging, University Hospital Zurich, Ramistrasse 100, Zurich 8091, Switzerland
| | - Lukas Keller
- Department of Nuclear Medicine, Cardiac Imaging, University Hospital Zurich, Ramistrasse 100, Zurich 8091, Switzerland
| | - Daniel Sepulcri
- Department of Nuclear Medicine, Cardiac Imaging, University Hospital Zurich, Ramistrasse 100, Zurich 8091, Switzerland
| | - Reto Boehm
- Department of Nuclear Medicine, Cardiac Imaging, University Hospital Zurich, Ramistrasse 100, Zurich 8091, Switzerland
| | - Chrysoula Garefa
- Department of Nuclear Medicine, Cardiac Imaging, University Hospital Zurich, Ramistrasse 100, Zurich 8091, Switzerland
| | | | | | | | | | | | | | - Barbara E Stähli
- Department of Cardiology, University Heart Center, University Hospital Zurich, Zurich, Switzerland
| | - Julia Stehli
- Department of Cardiology, University Heart Center, University Hospital Zurich, Zurich, Switzerland
| | - Aju P Pazhenkottil
- Department of Nuclear Medicine, Cardiac Imaging, University Hospital Zurich, Ramistrasse 100, Zurich 8091, Switzerland
| | - Philipp A Kaufmann
- Department of Nuclear Medicine, Cardiac Imaging, University Hospital Zurich, Ramistrasse 100, Zurich 8091, Switzerland
| | - Ronny R Buechel
- Department of Nuclear Medicine, Cardiac Imaging, University Hospital Zurich, Ramistrasse 100, Zurich 8091, Switzerland
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Verelst E, Buls N, De Mey J, Nieboer KH, Vandenbergh F, Crotty D, Deak P, Sundvall A, Holmin S, De Smet A, Provyn S, Van Gompel G. Stent appearance in a novel silicon-based photon-counting CT prototype: ex vivo phantom study in head-to-head comparison with conventional energy-integrating CT. Eur Radiol Exp 2023; 7:23. [PMID: 37097376 PMCID: PMC10130245 DOI: 10.1186/s41747-023-00333-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [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: 01/31/2023] [Accepted: 02/23/2023] [Indexed: 04/26/2023] Open
Abstract
BACKGROUND In this study, stent appearance in a novel silicon-based photon-counting computed tomography (Si-PCCT) prototype was compared with a conventional energy-integrating detector CT (EIDCT) system. METHODS An ex vivo phantom was created, consisting of a 2% agar-water mixture, in which human-resected and stented arteries were individually embedded. Using similar technique parameters, helical scan data was acquired using a novel prototype Si-PCCT and a conventional EIDCT system at a volumetric CT dose index (CTDIvol) of 9 mGy. Reconstructions were made at 502 and 1502 mm2 field-of-views (FOVs) using a bone kernel and adaptive statistical iterative reconstruction with 0% blending. Using a 5-point Likert scale, reader evaluations were performed on stent appearance, blooming and inter-stent visibility. Quantitative image analysis was performed on stent diameter accuracy, blooming and inter-stent distinction. Qualitative and quantitative differences between Si-PCCT and EIDCT systems were tested with a Wilcoxon signed-rank test and a paired samples t-test, respectively. Inter- and intra-reader agreement was assessed using the intraclass correlation coefficient (ICC). RESULTS Qualitatively, Si-PCCT images were rated higher than EIDCT images at 150-mm FOV, based on stent appearance (p = 0.026) and blooming (p = 0.015), with a moderate inter- (ICC = 0.50) and intra-reader (ICC = 0.60) agreement. Quantitatively, Si-PCCT yielded more accurate diameter measurements (p = 0.001), reduced blooming (p < 0.001) and improved inter-stent distinction (p < 0.001). Similar trends were observed for the images reconstructed at 50-mm FOV. CONCLUSIONS When compared to EIDCT, the improved spatial resolution of Si-PCCT yields enhanced stent appearance, more accurate diameter measurements, reduced blooming and improved inter-stent distinction. KEY POINTS • This study evaluated stent appearance in a novel silicon-based photon-counting computed tomography (Si-PCCT) prototype. • Compared to standard CT, Si-PCCT resulted in more accurate stent diameter measurements. • Si-PCCT also reduced blooming artefacts and improved inter-stent visibility.
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Affiliation(s)
- Emma Verelst
- Department of Radiology, Vrije Universiteit Brussel (VUB), Universitair Ziekenhuis Brussel (UZB), Laarbeeklaan 101, 1090, Brussels, Belgium.
| | - Nico Buls
- Department of Radiology, Vrije Universiteit Brussel (VUB), Universitair Ziekenhuis Brussel (UZB), Laarbeeklaan 101, 1090, Brussels, Belgium
| | - Johan De Mey
- Department of Radiology, Vrije Universiteit Brussel (VUB), Universitair Ziekenhuis Brussel (UZB), Laarbeeklaan 101, 1090, Brussels, Belgium
| | - Koenraad Hans Nieboer
- Department of Radiology, Vrije Universiteit Brussel (VUB), Universitair Ziekenhuis Brussel (UZB), Laarbeeklaan 101, 1090, Brussels, Belgium
| | - Frans Vandenbergh
- Department of Radiology, Vrije Universiteit Brussel (VUB), Universitair Ziekenhuis Brussel (UZB), Laarbeeklaan 101, 1090, Brussels, Belgium
| | | | - Paul Deak
- GE Healthcare, Waukesha, WI, 53188, USA
| | - Albert Sundvall
- Department of Medical Radiation Physics and Nuclear Medicine, Karolinska University Hospital, 171 76, Stockholm, Sweden
| | - Staffan Holmin
- Department of Clinical Neuroscience, Karolinska Institutet and Department of Neuroradiology, 171 74, Stockholm, Sweden
| | - Aron De Smet
- Anatomical Research Training and Education, Vrije Universiteit Brussel, 1090, Brussels, Belgium
| | - Steven Provyn
- Anatomical Research Training and Education, Vrije Universiteit Brussel, 1090, Brussels, Belgium
| | - Gert Van Gompel
- Department of Radiology, Vrije Universiteit Brussel (VUB), Universitair Ziekenhuis Brussel (UZB), Laarbeeklaan 101, 1090, Brussels, Belgium
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Naghavi-Behzad M, Vogsen M, Gerke O, Dahlsgaard-Wallenius SE, Nissen HJ, Jakobsen NM, Braad PE, Vilstrup MH, Deak P, Hildebrandt MG, Andersen TL. Comparison of Image Quality and Quantification Parameters between Q.Clear and OSEM Reconstruction Methods on FDG-PET/CT Images in Patients with Metastatic Breast Cancer. J Imaging 2023; 9:jimaging9030065. [PMID: 36976116 PMCID: PMC10058454 DOI: 10.3390/jimaging9030065] [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: 01/23/2023] [Revised: 03/01/2023] [Accepted: 03/07/2023] [Indexed: 03/11/2023] Open
Abstract
We compared the image quality and quantification parameters through bayesian penalized likelihood reconstruction algorithm (Q.Clear) and ordered subset expectation maximization (OSEM) algorithm for 2-[18F]FDG-PET/CT scans performed for response monitoring in patients with metastatic breast cancer in prospective setting. We included 37 metastatic breast cancer patients diagnosed and monitored with 2-[18F]FDG-PET/CT at Odense University Hospital (Denmark). A total of 100 scans were analyzed blinded toward Q.Clear and OSEM reconstruction algorithms regarding image quality parameters (noise, sharpness, contrast, diagnostic confidence, artefacts, and blotchy appearance) using a five-point scale. The hottest lesion was selected in scans with measurable disease, considering the same volume of interest in both reconstruction methods. SULpeak (g/mL) and SUVmax (g/mL) were compared for the same hottest lesion. There was no significant difference regarding noise, diagnostic confidence, and artefacts within reconstruction methods; Q.Clear had significantly better sharpness (p < 0.001) and contrast (p = 0.001) than the OSEM reconstruction, while the OSEM reconstruction had significantly less blotchy appearance compared with Q.Clear reconstruction (p < 0.001). Quantitative analysis on 75/100 scans indicated that Q.Clear reconstruction had significantly higher SULpeak (5.33 ± 2.8 vs. 4.85 ± 2.5, p < 0.001) and SUVmax (8.27 ± 4.8 vs. 6.90 ± 3.8, p < 0.001) compared with OSEM reconstruction. In conclusion, Q.Clear reconstruction revealed better sharpness, better contrast, higher SUVmax, and higher SULpeak, while OSEM reconstruction had less blotchy appearance.
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Affiliation(s)
- Mohammad Naghavi-Behzad
- Department of Clinical Research, University of Southern Denmark, 5000 Odense, Denmark (T.L.A.)
- Department of Nuclear Medicine, Odense University Hospital, 5000 Odense, Denmark
- Centre for Personalized Response Monitoring in Oncology, Odense University Hospital, 5000 Odense, Denmark
- Correspondence: ; Tel.: +45-9160-9622
| | - Marianne Vogsen
- Department of Clinical Research, University of Southern Denmark, 5000 Odense, Denmark (T.L.A.)
- Department of Nuclear Medicine, Odense University Hospital, 5000 Odense, Denmark
- Centre for Personalized Response Monitoring in Oncology, Odense University Hospital, 5000 Odense, Denmark
- Department of Oncology, Odense University Hospital, 5000 Odense, Denmark
| | - Oke Gerke
- Department of Clinical Research, University of Southern Denmark, 5000 Odense, Denmark (T.L.A.)
- Department of Nuclear Medicine, Odense University Hospital, 5000 Odense, Denmark
| | - Sara Elisabeth Dahlsgaard-Wallenius
- Department of Clinical Research, University of Southern Denmark, 5000 Odense, Denmark (T.L.A.)
- Department of Nuclear Medicine, Odense University Hospital, 5000 Odense, Denmark
| | - Henriette Juel Nissen
- Department of Clinical Research, University of Southern Denmark, 5000 Odense, Denmark (T.L.A.)
- Department of Nuclear Medicine, Odense University Hospital, 5000 Odense, Denmark
| | - Nick Møldrup Jakobsen
- Department of Clinical Research, University of Southern Denmark, 5000 Odense, Denmark (T.L.A.)
- Department of Nuclear Medicine, Odense University Hospital, 5000 Odense, Denmark
| | - Poul-Erik Braad
- Department of Clinical Research, University of Southern Denmark, 5000 Odense, Denmark (T.L.A.)
- Department at Clinical Engineering, Region of Southern Denmark, 6200 Aabenraa, Denmark
| | - Mie Holm Vilstrup
- Department of Clinical Research, University of Southern Denmark, 5000 Odense, Denmark (T.L.A.)
- Department of Nuclear Medicine, Odense University Hospital, 5000 Odense, Denmark
| | - Paul Deak
- Healthcare Science Technology, GE Healthcare, Chicago, IL 06828, USA
| | - Malene Grubbe Hildebrandt
- Department of Clinical Research, University of Southern Denmark, 5000 Odense, Denmark (T.L.A.)
- Department of Nuclear Medicine, Odense University Hospital, 5000 Odense, Denmark
- Centre for Personalized Response Monitoring in Oncology, Odense University Hospital, 5000 Odense, Denmark
- Centre for Innovative Medical Technology, Odense University Hospital, 5000 Odense, Denmark
| | - Thomas Lund Andersen
- Department of Clinical Research, University of Southern Denmark, 5000 Odense, Denmark (T.L.A.)
- Department of Clinical Physiology and Nuclear Medicine, Rigshospitalet, 2100 Copenhagen, Denmark
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Franck C, Snoeckx A, Spinhoven M, El Addouli H, Nicolay S, Van Hoyweghen A, Deak P, Zanca F. PULMONARY NODULE DETECTION IN CHEST CT USING A DEEP LEARNING-BASED RECONSTRUCTION ALGORITHM. Radiat Prot Dosimetry 2021; 195:158-163. [PMID: 33723584 DOI: 10.1093/rpd/ncab025] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Revised: 01/14/2021] [Accepted: 02/05/2021] [Indexed: 06/12/2023]
Abstract
This study's aim was to assess whether deep learning image reconstruction (DLIR) techniques are non-inferior to ASIR-V for the clinical task of pulmonary nodule detection in chest computed tomography. Up to 6 (range 3-6, mean 4.2) artificial lung nodules (diameter: 3, 5, 8 mm; density: -800, -630, +100 HU) were inserted at different locations in the Kyoto Kagaku Lungman phantom. In total, 16 configurations (10 abnormal, 6 normal) were scanned at 7.6, 3, 1.6 and 0.38 mGy CTDIvol (respectively 0, 60, 80 and 95% dose reduction). Images were reconstructed using 50% ASIR-V and a deep learning-based algorithm with low (DL-L), medium (DL-M) and high (DL-H) strength. Four chest radiologists evaluated 256 series by locating and scoring nodules on a five-point scale. No statistically significant difference was found among the reconstruction algorithms (p = 0.987, average across readers AUC: 0.555, 0.561, 0.557, 0.558 for ASIR-V, DL-L, DL-M, DL-H).
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Affiliation(s)
- C Franck
- Department of Radiology, University Hospital Antwerp, Drie Eikenstraat 655, 2650 Edegem, Belgium
- mVISION, Faculty of Medicine and Health Sciences, University of Antwerp, Drie Eikenstraat 655, 2650 Edegem, Belgium
| | - A Snoeckx
- Department of Radiology, University Hospital Antwerp, Drie Eikenstraat 655, 2650 Edegem, Belgium
- mVISION, Faculty of Medicine and Health Sciences, University of Antwerp, Drie Eikenstraat 655, 2650 Edegem, Belgium
| | - M Spinhoven
- Department of Radiology, University Hospital Antwerp, Drie Eikenstraat 655, 2650 Edegem, Belgium
- mVISION, Faculty of Medicine and Health Sciences, University of Antwerp, Drie Eikenstraat 655, 2650 Edegem, Belgium
| | - H El Addouli
- Department of Radiology, University Hospital Antwerp, Drie Eikenstraat 655, 2650 Edegem, Belgium
- mVISION, Faculty of Medicine and Health Sciences, University of Antwerp, Drie Eikenstraat 655, 2650 Edegem, Belgium
| | - S Nicolay
- Department of Radiology, University Hospital Antwerp, Drie Eikenstraat 655, 2650 Edegem, Belgium
- mVISION, Faculty of Medicine and Health Sciences, University of Antwerp, Drie Eikenstraat 655, 2650 Edegem, Belgium
| | - A Van Hoyweghen
- Department of Radiology, University Hospital Antwerp, Drie Eikenstraat 655, 2650 Edegem, Belgium
- mVISION, Faculty of Medicine and Health Sciences, University of Antwerp, Drie Eikenstraat 655, 2650 Edegem, Belgium
| | - P Deak
- GE Healthcare, Glattbrugg, Switzerland
| | - F Zanca
- Palindromo Consulting, Leuven, Belgium
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Franck C, Zhang G, Deak P, Zanca F. Preserving image texture while reducing radiation dose with a deep learning image reconstruction algorithm in chest CT: A phantom study. Phys Med 2021; 81:86-93. [PMID: 33445125 DOI: 10.1016/j.ejmp.2020.12.005] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Revised: 11/23/2020] [Accepted: 12/05/2020] [Indexed: 02/03/2023] Open
Abstract
PURPOSE To assess whether a deep learning image reconstruction algorithm (TrueFidelity) can preserve the image texture of conventional filtered back projection (FBP) at reduced dose levels attained by ASIR-V in chest CT. METHODS Phantom images were acquired using a clinical chest protocol (7.6 mGy) and two levels of dose reduction (60% and 80%). Images were reconstructed with FBP, ASIR-V (50% and 100% blending) and TrueFidelity (low (DL-L), medium (DL-M) and high (DL-H) strength). Noise (SD), noise power spectrum (NPS) and task-based transfer function (TTF) were calculated. Noise texture was quantitatively compared by computing root-mean-square deviations (RMSD) of NPS with respect to FBP. Four experienced readers performed a contrast-detail evaluation. The dose reducing potential of TrueFidelity compared to ASIR-V was assessed by fitting SD and contrast-detail as a function of dose. RESULTS DL-M and DL-H reduced noise and NPS area compared to FBP and 50% ASIR-V, at all dose levels. At 7.6 mGy, NPS of ASIR-V 50/100% was shifted towards lower frequencies (fpeak = 0.22/0.13 mm-1, RMSD = 0.14/0.38), with respect to FBP (fpeak = 0.30 mm-1). Marginal difference was observed for TrueFidelity: fpeak = 0.33/0.30/0.30 mm-1 and RMSD = 0.03/0.04/0.07 for L/M/H strength. Values of TTF50% were independent of DL strength and higher compared to FBP and ASIR-V, at all dose and contrast levels. Contrast-detail was highest for DL-H at all doses. Compared to 50% ASIR-V, DL-H had an estimated dose reducing potential of 50% on average, without impairing noise, texture and detectability. CONCLUSIONS TrueFidelity preserves the image texture of FBP, while outperforming ASIR-V in terms of noise, spatial resolution and detectability at lower doses.
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Affiliation(s)
- Caro Franck
- Department of Radiology, University Hospital Antwerp, Drie Eikenstraat 655, 2650 Edegem, Belgium; mVISION, Faculty of Medicine and Health Sciences, University of Antwerp, Drie Eikenstraat 655, 2650 Edegem, Belgium.
| | - Guozhi Zhang
- Department of Radiology, KU Leuven University Hospitals Leuven, Leuven, Belgium
| | - Paul Deak
- GE Healthcare, Glattbrugg, Switzerland
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Vallot D, De Ponti E, Morzenti S, Gramek A, Pieczonka A, Llompart GR, Siennicki J, Deak P, Dutta C, Uribe J, Caselles O. Evaluation of PET quantitation accuracy among multiple discovery IQ PET/CT systems via NEMA image quality test. EJNMMI Phys 2020; 7:30. [PMID: 32399647 PMCID: PMC7218035 DOI: 10.1186/s40658-020-00294-y] [Citation(s) in RCA: 7] [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] [Subscribe] [Scholar Register] [Received: 10/15/2019] [Accepted: 03/27/2020] [Indexed: 12/20/2022] Open
Abstract
Introduction Quantitative imaging biomarkers are becoming usual in oncology for assessing therapy response. The harmonization of image quantitation reporting has become of utmost importance due to the multi-center trials increase. The NEMA image quality test is often considered for the evaluation of quantitation and is more accurate with a radioactive solid phantom that reduces variability. The goal of this project is to determine the level of variability among imaging centers if acquisition and imaging protocol parameters are left to the center’s preference while all other parameters are fixed including the scanner type. Methods A NEMA-IQ phantom filled with radioactive 68Ge solid resin was imaged in five clinical sites throughout Europe. Sites reconstructed data with OSEM and BSREM algorithms applying the sites’ clinical parameters. Images were analyzed according with the NEMA-NU2-2012 standard using the manufacturer-provided NEMA tools to calculate contrast recovery (CR) and background variability (BV) for each sphere and the lung error (LE) estimation. In addition, a 18F-filled NEMA-IQ phantom was also evaluated to obtain a gauge for variability among centers when the sites were provided with identical specific instructions for acquisition and reconstruction protocol (the aggregate of data from 12 additional sites is presented). Results The data using the 68Ge solid phantom showed no statistical differences among different sites, proving a very good reproducibility among the PET center models even if dispersion of data is higher with OSEM compared to BSREM. Furthermore, BSREM shows better CR and comparable BV, while LE is slightly reduced. Two centers exhibit significant differences in CR and BV values for the 18F NEMA NU2-2012 experiments; these outlier results are explained. Conclusion The same PET system type from the various sites produced similar quantitative results, despite allowing each site to choose their clinical protocols with no restriction on data acquisition and reconstruction parameters. BSREM leads to lower dispersion of quantitative data among different sites. A solid radioactive phantom may be recommended to qualify the sites to perform quantitative imaging.
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Affiliation(s)
- Delphine Vallot
- Medical Physics Department, Institut Claudius Regaud, Toulouse, France.
| | - Elena De Ponti
- Medical Physics Department, ASST-Monza, San Gerardo Hospital, Italy
| | - Sabrina Morzenti
- Medical Physics Department, ASST-Monza, San Gerardo Hospital, Italy
| | | | | | | | | | - Paul Deak
- General Electric Healthcare, Waukesha, USA
| | | | | | - Olivier Caselles
- Medical Physics Department, Institut Claudius Regaud, Toulouse, France
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Geyer LL, Scherr M, Körner M, Wirth S, Deak P, Reiser MF, Linsenmaier U. Imaging of acute pulmonary embolism using a dual energy CT system with rapid kVp switching: Initial results. Eur J Radiol 2012; 81:3711-8. [DOI: 10.1016/j.ejrad.2011.02.043] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2011] [Accepted: 02/22/2011] [Indexed: 11/15/2022]
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May MS, Deak P, Kuettner A, Lell MM, Wuest W, Scharf M, Keller AK, Häberle L, Achenbach S, Seltmann M, Uder M, Kalender WA. Radiation dose considerations by intra-individual Monte Carlo simulations in dual source spiral coronary computed tomography angiography with electrocardiogram-triggered tube current modulation and adaptive pitch. Eur Radiol 2011; 22:569-78. [PMID: 21984448 DOI: 10.1007/s00330-011-2300-6] [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] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2011] [Revised: 09/09/2011] [Accepted: 09/13/2011] [Indexed: 11/24/2022]
Abstract
OBJECTIVES To evaluate radiation dose levels in patients undergoing spiral coronary computed tomography angiography (CTA) on a dual-source system in clinical routine. METHODS Coronary CTA was performed for 56 patients with electrocardiogram-triggered tube current modulation (TCM) and heart-rate (HR) dependent pitch adaptation. Individual Monte Carlo (MC) simulations were performed for dose assessment. Retrospective simulations with constant tube current (CTC) served as reference. Lung tissue was segmented and used for organ and effective dose (ED) calculation. RESULTS Estimates for mean relative ED was 7.1 ± 2.1 mSv/100 mAs for TCM and 12.5 ± 5.3 mSv/100 mAs for CTC (P < 0.001). Relative dose reduction at low HR (≤60 bpm) was highest (49 ± 5%) compared to intermediate (60-70 bpm, 33 ± 12%) and high HR (>70 bpm, 29 ± 12%). However lowest ED is achieved at high HR (5.2 ± 1.5 mSv/100 mAs), compared with intermediate (6.7 ± 1.6 mSv/100 mAs) and low (8.3 ± 2.1 mSv/100 mAs) HR when automated pitch adaptation is applied. CONCLUSIONS Radiation dose savings up to 52% are achievable by TCM at low and regular HR. However lowest ED is attained at high HR by pitch adaptation despite inferior radiation dose reduction by TCM. KEY POINTS • Monte Carlo simulations allow for individual radiation dose calculations. • ECG-triggered tube current modulation (TCM) can effectively reduce radiation dose. • Slow and regular heart rates allow for highest dose reductions by TCM. • Adaptive pitch accounts for lowest radiation dose at high heart rates. • Women receive higher effective dose than men undergoing spiral coronary CT-angiography.
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Affiliation(s)
- Matthias S May
- Department of Radiology, University of Erlangen, Maximiliansplatz 1, 91054 Erlangen, Germany.
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van Straten M, Deak P, Shrimpton PC, Kalender WA. The effect of angular and longitudinal tube current modulations on the estimation of organ and effective doses in x-ray computed tomography. Med Phys 2010; 36:4881-9. [PMID: 19994496 DOI: 10.1118/1.3231948] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
PURPOSE Tube current modulation (TCM) is one of the recent developments in multislice CT that has proven to reduce the patient radiation dose without affecting the image quality. Presently established methods and published coefficients for estimating organ doses from the dose measured free in air on the axis of rotation or in the CT dose index (CTDI) dosimetry phantoms do not take into account this relatively new development in CT scanner design and technology. Based on these organ dose coefficients effective dose estimates can be made. The estimates are not strictly valid for CT scanning protocols utilizing TCM. In this study, the authors investigated the need to take TCM into account when estimating organ and effective dose values. METHODS A whole-body adult anthropomorphic phantom (Alderson Rando) was scanned with a multislice CT scanner (Somatom Definition, Siemens, Forchheim, Germany) utilizing TCM (CareDose4D). Tube voltage was 120 kV, beam collimation 19.2 mm, and pitch 1. A voxelized patient model was used to define the tissues and organs in the phantom. Tube current values as a function of tube angle were obtained from the raw data for each individual tube rotation of the scan. These values were used together with the Monte Carlo dosimetry tool IMPACTMC (VAMP GmbH, Erlangen, Germany) to calculate organ dose values both with and without account of TCM. Angular and longitudinal modulations were investigated separately. Finally, corresponding effective dose conversion coefficients were determined for both cases according to the updated 2007 recommendations of the ICRP. RESULTS TCM amplitude was greatest in the shoulder and pelvic regions. Consequently, dose distributions and organ dose values for particular cross sections changed considerably when taking angular modulation into account. The effective dose conversion coefficients were up to 11% lower for a single rotation in the shoulder region and 17% lower in the pelvis when taking angular TCM into account. In the head, neck, thorax, and upper abdominal regions, conversion coefficients changed similarly by only 5% or less. Conversion coefficients for estimating effective doses for scans of complete regions, e.g., chest or abdomen, were approximately 8% lower when taking angular and longitudinal TCMs into account. CONCLUSIONS The authors conclude that for accurate organ and effective dose estimates in individual cross sections in the shoulder or pelvic regions, the angular tube current modulation should be taken into account. In general, using the average of the modulated tube current causes an overestimation of the effective dose.
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Affiliation(s)
- Marcel van Straten
- Institute of Medical Physics, University Erlangen-Nürnberg, Henkestrasse 91, 91052 Erlangen, Germany.
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Kalender WA, Deak P, Kellermeier M, van Straten M, Vollmar SV. Application- and patient size-dependent optimization of x-ray spectra for CT. Med Phys 2009; 36:993-1007. [DOI: 10.1118/1.3075901] [Citation(s) in RCA: 163] [Impact Index Per Article: 10.9] [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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Abstract
Flat-detector computed tomography (FD-CT) scanners provide large irradiation fields of typically 200 mm in the cranio-caudal direction. In consequence, dose assessment according to the current definition of the computed tomography dose index CTDI(L=100 mm), where L is the integration length, would demand larger ionization chambers and phantoms which do not appear practical. We investigated the usefulness of the CTDI concept and practical dosimetry approaches for FD-CT by measurements and Monte Carlo (MC) simulations. An MC simulation tool (ImpactMC, VAMP GmbH, Erlangen, Germany) was used to assess the dose characteristics and was calibrated with measurements of air kerma. For validation purposes measurements were performed on an Axiom Artis C-arm system (Siemens Medical Solutions, Forchheim, Germany) equipped with a flat detector of 40 cm x 30 cm. The dose was assessed for 70 kV and 125 kV in cylindrical PMMA phantoms of 160 mm and 320 mm diameter with a varying phantom length from 150 to 900 mm. MC simulation results were compared to the values obtained with a calibrated ionization chambers of 100 mm and 250 mm length and to thermoluminesence (TLD) dose profiles. The MCs simulations were used to calculate the efficiency of the CTDI(L) determination with respect to the desired CTDI(infinity). Both the MC simulation results and the dose distributions obtained by MC simulation were in very good agreement with the CTDI measurements and with the reference TLD profiles, respectively, to within 5%. Standard CTDI phantoms which have a z-extent of 150 mm underestimate the dose at the center by up to 55%, whereas a z-extent of 600 mm appears to be sufficient for FD-CT; the baseline value of the respective profile was within 1% to the reference baseline. As expected, the measurements with ionization chambers of 100 mm and 250 mm offer a limited accuracy, whereas an increased integration length of 600 mm appeared to be necessary to approximate CTDI(infinity) in within 1%. MC simulations appear to offer a practical and accurate way of assessing conversion factors for arbitrary dosimetry setups using a standard pencil chamber to provide estimates of CTDI(infinity). This would eliminate the need for extra-long phantoms and ionization chambers or excessive amounts of TLDs.
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Affiliation(s)
- Yiannis Kyriakou
- Institute of Medical Physics, University of Erlangen-Nuremberg, Germany.
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Kalender WA, Buchenau S, Deak P, Kellermeier M, Langner O, van Straten M, Vollmar S, Wilharm S. Technical approaches to the optimisation of CT. Phys Med 2008; 24:71-9. [PMID: 18331808 DOI: 10.1016/j.ejmp.2008.01.012] [Citation(s) in RCA: 133] [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] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/10/2007] [Revised: 01/08/2008] [Accepted: 01/09/2008] [Indexed: 12/17/2022] Open
Abstract
This paper reviews current technical approaches to the optimisation of CT practice, i.e. approaches to reduce patient dose to the necessary minimum. The most important step towards this goal appears to be the technology of tube current modulation (TCM), which came into practice in the early 2000s and has become the standard approach recently. Anatomy- or attenuation-based TCM allows for a dose reduction between 10 and 60% as compared to scans with constant tube current. Automatic exposure control (AEC) approaches are the next step; based on TCM technology, AEC adapts the tube current both with the rotation angle alpha (alpha-modulation) and along the z-axis (z-modulation) to achieve a pre-selected image quality level at minimal dose. To pre-select the image quality level, i.e. primarily the pixel noise level, tools for simulation are important to investigate the necessary noise levels pro- and retrospectively for given cases and diagnostic tasks. Respective "dose tutor" approaches have become available recently and are presented. The most recent technical innovation which may lead to substantial dose reduction is the investigation of optimal spectra taking the type of contrast and 3D dose distributions into account. A high potential has been shown especially for pediatric CT and for thoracic CT where dose reduction of a factor of 2 and more is possible when using reduced tube voltages.
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Affiliation(s)
- Willi A Kalender
- Institute of Medical Physics, University of Erlangen-Nuernberg, Henkestrasse 91, Erlangen D-91052, Germany.
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Kyriakou Y, Krause J, Langner O, Deak P, Kalender W. TU-C-L100J-10: Combining Measurement and Monte Carlo Methods for Dose Assessment in Flat-Detector CT. Med Phys 2007. [DOI: 10.1118/1.2761330] [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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Gali A, Aradi B, Deak P, Choyke WJ, Son NT. Overcoordinated hydrogens in the carbon vacancy: donor centers of SiC. Phys Rev Lett 2000; 84:4926-4929. [PMID: 10990833 DOI: 10.1103/physrevlett.84.4926] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/23/1999] [Indexed: 05/23/2023]
Abstract
Epitaxial silicon carbide is likely to contain hydrogen and vacancies ( V); therefore, V+nH complexes are likely to influence its electronic properties. Using ab initio calculations we show that neutral and positive H atoms are trapped by carbon vacancies ( V(C)) in three-center bonds with two Si neighbors. The double positive charge state of V(C)+H is not stable in equilibrium and in the triply positive state H binds only to one of the Si neighbors. At most two H atoms can be accommodated by a single V(C). The V(C)+nH complexes have donor character and exhibit rather atypical vibration modes for Si-H bonds. Occupation levels and spin distributions were calculated and compared for V(C)+H and V(C).
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Affiliation(s)
- A Gali
- Department of Atomic Physics, Technical University of Budapest, Budafoki ut 8., H-1111, Budapest, Hungary
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Louis C, Madueño E, Modolell J, Omar MM, Papagiannakis G, Saunders RD, Savakis C, Sidén-Kiamos I, Spanos L, Topalis P, Zhang YQ, Ashburner M, Benos P, Bolshakov VN, Deak P, Glover DM, Herrmann S, Kafatos FC. One-hundred and five new potential Drosophila melanogaster genes revealed through STS analysis. Gene 1997; 195:187-93. [PMID: 9305763 DOI: 10.1016/s0378-1119(97)00138-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [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: 02/05/2023]
Abstract
Complementation analysis had suggested that the Drosophila melanogaster genome contains approximately 5000 genes, but it is now generally accepted that the actual number is several times as high. We report here an analysis of 1788 anonymous sequence tagged sites (STSs) from the European Drosophila Genome Project (EDGP), totalling 463 kb. The data reveal a substantial number of previously undescribed potential genes, amounting to 6.1% of the number of Drosophila genes already in the sequence databases.
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Affiliation(s)
- C Louis
- Institute of Molecular Biology and Biotechnology, FORTH, Heraklion, Crete, Greece.
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Raabe T, Riesgo-Escovar J, Liu X, Bausenwein BS, Deak P, Maröy P, Hafen E. DOS, a novel pleckstrin homology domain-containing protein required for signal transduction between sevenless and Ras1 in Drosophila. Cell 1996; 85:911-20. [PMID: 8681385 DOI: 10.1016/s0092-8674(00)81274-x] [Citation(s) in RCA: 166] [Impact Index Per Article: 5.9] [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: 02/01/2023]
Abstract
The specification of the R7 photoreceptor cell in the developing eye of Drosophila is dependent upon activation of the Sevenless (SEV) receptor tyrosine kinase. By screening for mutations that suppress signaling via a constitutively activated SEV protein, we have identified a novel gene, daughter of sevenless (dos). DOS is required not only for signal transduction via SEV but also in other receptor tyrosine kinase signaling pathways throughout development. The presence of an amino-terminally located pleckstrin homology domain and many potential tyrosine phosphorylation sites suggests that DOS functions as an adaptor protein able to interact with multiple signaling molecules. Our genetic analysis demonstrates that DOS functions upstream of Ras1 and defines a signaling pathway that is independent of direct binding of the DRK SH2/SH3 adaptor protein to the SEV receptor tyrosine kinase.
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Affiliation(s)
- T Raabe
- Theodor Boveri Institut für Biowissenschaften, Lehstuhl für Genetik, Universität Würzburg, Federal Republic of Germany
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Murtagh JJ, Lee FJ, Deak P, Hall LM, Monaco L, Lee CM, Stevens LA, Moss J, Vaughan M. Molecular characterization of a conserved, guanine nucleotide-dependent ADP-ribosylation factor in Drosophila melanogaster. Biochemistry 1993; 32:6011-8. [PMID: 8507638 DOI: 10.1021/bi00074a012] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.8] [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] [Indexed: 01/31/2023]
Abstract
ADP-Ribosylation factors (ARFs) are ubiquitous approximately 20-kDa guanine nucleotide-binding proteins that stimulate cholera toxin-catalyzed ADP-ribosylation in vitro. Because the functional role(s) of ARF in mammalian systems is (are) elusive, we looked for ARF in Drosophila melanogaster, and report the partial purification and molecular cloning of an ARF from Drosophila. We cloned the Drosophila ARF 1 gene without library screening by a combination of 5 polymerase chain reactions (PCRs), yielding a 546-base open reading frame encoding 182 amino acids, which are > 93% identical to those of mammalian class I ARFs. This ARF gene maps to 79F3-6 in the proximal region of the left arm of Drosophila chromosome 3. The Drosophila ARF1 gene structure, including placement of introns, is highly conserved relative to mammalian class 1 ARF genes. A single ARF mRNA species of 1.8 kb was abundant in all Drosophila body segments. Recombinant Drosophila ARF 1 synthesized in Escherichia coli had biochemical and immunochemical activities similar to those of mammalian ARF. The similarities of sequence and biochemical properties between Drosophila and mammalian ARFs contrast with their differences from Drosophila arl (ARF-like protein), which does not stimulate cholera toxin-catalyzed ADP-ribosylation, and is only approximately 52-56% identical in amino acid sequence to mammalian ARFs.
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Affiliation(s)
- J J Murtagh
- Laboratory of Cellular Metabolism, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland 20892
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Deak P. [Acroosteosclerosis]. Fortschr Geb Rontgenstr Nuklearmed 1958; 89:59-66. [PMID: 13562313] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 04/23/2023]
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