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牛 善, 刘 宏, 刘 沛, 张 梦, 李 硕, 梁 礼, 李 楠, 刘 国. [Nonlocal low-rank and sparse matrix decomposition for low-dose cerebral perfusion CT image restoration]. NAN FANG YI KE DA XUE XUE BAO = JOURNAL OF SOUTHERN MEDICAL UNIVERSITY 2022; 42:1309-1316. [PMID: 36210703 PMCID: PMC9550540 DOI: 10.12122/j.issn.1673-4254.2022.09.06] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 03/14/2022] [Indexed: 01/24/2023]
Abstract
OBJECTIVE To present a nonlocal low-rank and sparse matrix decomposition (NLSMD) method for low-dose cerebral perfusion CT image restoration. METHODS Low-dose cerebral perfusion CT images were first partitioned into a matrix, and the low- rank and sparse matrix decomposition model was constructed to obtain high-quality low-dose cerebral perfusion CT images. The cerebral hemodynamic parameters were calculated from the restored high-quality CT images. RESULTS In the phantom study, the average structured similarity (SSIM) value of the sequential images obtained by filtered back-projection (FBP) algorithm was 0.9438, which was increased to 0.9765 using the proposed algorithm; the SSIM values of cerebral blood flow (CBF) and cerebral blood volume (CBV) map obtained by FBP algorithm were 0.7005 and 0.6856, respectively, which were increased using the proposed algorithm to 0.7871 and 0.7972, respectively. CONCLUSION The proposed method can effectively suppress noises in low-dose cerebral perfusion CT images to obtain accurate cerebral hemodynamic parameters.
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Affiliation(s)
- 善洲 牛
- 赣南师范大学数学与计算机科学学院,江西 赣州 341000School of Mathematics and Computer Science, Gannan Normal University, Ganzhou 341000, China
- 赣南师范大学赣州市计算成像重点实验室,江西 赣州 341000Ganzhou Key Laboratory of Computational Imaging, Gannan Normal University, Ganzhou 341000, China
| | - 宏 刘
- 赣南师范大学数学与计算机科学学院,江西 赣州 341000School of Mathematics and Computer Science, Gannan Normal University, Ganzhou 341000, China
- 赣南师范大学赣州市计算成像重点实验室,江西 赣州 341000Ganzhou Key Laboratory of Computational Imaging, Gannan Normal University, Ganzhou 341000, China
| | - 沛沄 刘
- 赣南师范大学数学与计算机科学学院,江西 赣州 341000School of Mathematics and Computer Science, Gannan Normal University, Ganzhou 341000, China
- 赣南师范大学赣州市计算成像重点实验室,江西 赣州 341000Ganzhou Key Laboratory of Computational Imaging, Gannan Normal University, Ganzhou 341000, China
| | - 梦真 张
- 赣南师范大学数学与计算机科学学院,江西 赣州 341000School of Mathematics and Computer Science, Gannan Normal University, Ganzhou 341000, China
- 赣南师范大学赣州市计算成像重点实验室,江西 赣州 341000Ganzhou Key Laboratory of Computational Imaging, Gannan Normal University, Ganzhou 341000, China
| | - 硕 李
- 赣南师范大学数学与计算机科学学院,江西 赣州 341000School of Mathematics and Computer Science, Gannan Normal University, Ganzhou 341000, China
- 赣南师范大学赣州市计算成像重点实验室,江西 赣州 341000Ganzhou Key Laboratory of Computational Imaging, Gannan Normal University, Ganzhou 341000, China
| | - 礼境 梁
- 赣南师范大学数学与计算机科学学院,江西 赣州 341000School of Mathematics and Computer Science, Gannan Normal University, Ganzhou 341000, China
- 赣南师范大学赣州市计算成像重点实验室,江西 赣州 341000Ganzhou Key Laboratory of Computational Imaging, Gannan Normal University, Ganzhou 341000, China
| | - 楠 李
- 赣南师范大学经济管理学院,江西 赣州 341000School of Economics and Management, Gannan Normal University, Ganzhou 341000, China
| | - 国良 刘
- 赣南医学院医学信息工程学院,江西 赣州 341000School of Medical Information Engineering, Gannan Medical University, Ganzhou 341000, China
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Damulira E, Yusoff MNS, Omar AF, Mohd Taib NH. Development and characterization of an LED-based detector for dosimetry in diagnostic radiology. Phys Med Biol 2021; 66. [PMID: 33725685 DOI: 10.1088/1361-6560/abef44] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Accepted: 03/16/2021] [Indexed: 11/12/2022]
Abstract
Light-emitting diodes (LEDs) could be a potential dosimetry candidate because they are radiation hard, spectrally selective, direct band gap, and low-cost devices. Thus, an LED-based detector prototype was designed and characterized for dosimetry. A 20 × 20 cm2 array of surface mount device LED chips was sandwiched in photovoltaic mode between two intensifying screens to form a dosimetric system. The system was enclosed in a light-tight air cavity using black vinyl tape. The screens converted diagnostic X-ray beams into fluorescent blue light. LEDs, applied in detector mode, converted the fluorescent light into radiation-induced currents. A digital multimeter converted the analog currents into digital voltage signals. Prototype characterization was executed using (a) IEC 61267's RQR 7 (90 kVp) and RQR 8 (100 kVp) beam qualities, and (b) low (25 mAs) and high (80 mAs) beam quantities. A standard dosimeter probe was simultaneously exposed with the prototype to measure the prototype's absorbed dose. In all exposures, the X-ray beams were perpendicularly incident on both the dosimeter and prototype, at a fixed source to detector distance-60 cm. The LED array prototype's minimum detectable dose was 0.139 mGy, and the maximum dose implemented herein was ~ 13 mGy. The prototype was 99.18 % and 98.64 % linearly sensitive to absorbed dose and tube current-time product (mAs), respectively. The system was ± 4.69 % energy, ± 6.8 % dose, and ± 7.7 % dose rate dependent. Two prototype data sets were 89.93 % repeatable. We fabricated an ultrathin (5 mm), lightweight (130 g), and a relatively low-cost LED-based dosimetric prototype. The prototype executed a simple, efficient, and accurate real-time dosimetric mechanism. It could thus be an alternative to the current passive dosimetric systems.
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Affiliation(s)
- Edrine Damulira
- Medical Radiation, Universiti Sains Malaysia, 16150 Kubang Kerian, Kelantan, Kota Bharu, 16150, MALAYSIA
| | | | - Ahmad Fairuz Omar
- School of Physics, Universiti Sains Malaysia, Minden, Pulau Pinang, MALAYSIA
| | - Nur Hartini Mohd Taib
- Department of Radiology, School of Medical Sciences, Universiti Sains Malaysia, Kota Bahru, Kelantan, MALAYSIA
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Damulira E, Yusoff MNS, Omar AF, Mohd Taib NH, Ahmed NM. Application of Bpw34 photodiode and cold white LED as diagnostic X-ray detectors: A comparative analysis. Appl Radiat Isot 2021; 170:109622. [PMID: 33592486 DOI: 10.1016/j.apradiso.2021.109622] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2020] [Revised: 12/17/2020] [Accepted: 01/26/2021] [Indexed: 11/25/2022]
Abstract
This study compares the real-time dosimetric performance of a bpw34 photodiode (PD) and cold white light-emitting diodes (LEDs) based on diagnostic X-ray-induced signals. Signals were extracted when both the transducers were under identical exposure settings, including source-to-detector distance (SDD), tube voltage (kVp), and current-time product (mAs). The transducers were in a photovoltaic configuration, and black vinyl tape was applied on transducer active areas as a form of optical shielding. X-ray beam spectra and energies were simulated using Matlab-based Spektr functions. Transducer performance analysis was based on signal linearity to mAs and air kerma, and sensitivity dependence on absorbed dose, energy, and dose rate. Bpw34 PD and cold white LED output signals were 84.8% and 85.5% precise, respectively. PD signals were 94.7% linear to mAs, whereas LED signals were 91.9%. PD and LED signal linearity to dose coefficients were 0.9397 and 0.9128, respectively. Both transducers exhibited similar dose and energy dependence. However, cold white LEDs were 0.73% less dose rate dependent than the bpw34 PD. Cold white LEDs demonstrated potential in detecting diagnostic X-rays because their performance was similar to that of the bpw34 PD. Moreover, the cold white LED array's dosimetric response was independent of the heel effect. Although cold white LED signals were lower than bpw34 PD signals, they were quantifiable and electronically amplifiable.
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Affiliation(s)
- Edrine Damulira
- Medical Radiation Programme, School of Health Sciences, Universiti Sains Malaysia, Kubang Kerian, 16150, Malaysia.
| | - Muhammad Nur Salihin Yusoff
- Medical Radiation Programme, School of Health Sciences, Universiti Sains Malaysia, Kubang Kerian, 16150, Malaysia.
| | - Ahmad Fairuz Omar
- Engineering Physics Laboratory, School of Physics, Universiti Sains Malaysia, Penang, 11800, Malaysia
| | - Nur Hartini Mohd Taib
- Department of Radiology, School of Medical Sciences, Universiti Sains Malaysia, Kubang Kerian, 16150, Malaysia
| | - Naser M Ahmed
- School of Physics, Universiti Sains Malaysia, Penang, 11800, Malaysia
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Canton GP, Luvizutto GJ, Hamamoto Filho PT, Minicucci MF, Modolo GP, Trindade AP, Bazan R, Souza JTD. Safety of the effective radiation dose received during stroke hospitalization. J Vasc Bras 2021; 20:e20210142. [PMID: 35096032 PMCID: PMC8759585 DOI: 10.1590/1677-5449.210142] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2021] [Accepted: 10/27/2021] [Indexed: 11/21/2022] Open
Abstract
Background Neuroimaging is widely used for diagnosis and treatment of stroke. However, little is known about whether the radiation doses received by patients comply with international safety guidelines. Objectives The aim of this study was to evaluate the effective radiation dose received while in hospital for stroke and analyze its safety according to current guidelines. Methods This cross-sectional study included 109 patients who were hospitalized and diagnosed with ischemic stroke. The National Institutes of Health Stroke Scale was used to evaluate stroke severity, the Bamford clinical classification was used for topography, and the TOAST classification was used for etiology. The computed tomography dose index and size-specific dose estimates were used to calculate the effective radiation dose (ERD) received while in hospital. A Mann-Whitney test was used to compare the ERD received by thrombolysed and non-thrombolysed patients. Non-parametric statistics were used to analyze the data with a 95% confidence interval. Results During the study period, the median ERD received was 10.9 mSv. Length of stay was not associated with radiation exposure. No differences were demonstrated in ERD according to stroke etiology or Bamford clinical classification. Patients who had CT perfusion (only or in addition to CT or angiotomography) received the highest ERD (46.5 mSv) and the difference compared to those who did not (10.8 mSv) was statistically significant (p<0.001). No differences were found in the ERD between thrombolysed and non-thrombolysed patients. There was no correlation between ERD while in hospital and stroke severity. Conclusions According to the current national guidelines, the protocol for examining images at our stroke unit is safe in terms of the ERD received by the patient while in hospital. There was no difference in the ERD received by patients stratified by thrombolytic treatment or stroke severity.
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A Novel Singular Value Decomposition-Based Denoising Method in 4-Dimensional Computed Tomography of the Brain in Stroke Patients with Statistical Evaluation. SENSORS 2020; 20:s20113063. [PMID: 32481740 PMCID: PMC7309118 DOI: 10.3390/s20113063] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Revised: 05/24/2020] [Accepted: 05/25/2020] [Indexed: 11/16/2022]
Abstract
Computed tomography (CT) is a widely used medical imaging modality for diagnosing various diseases. Among CT techniques, 4-dimensional CT perfusion (4D-CTP) of the brain is established in most centers for diagnosing strokes and is considered the gold standard for hyperacute stroke diagnosis. However, because the detrimental effects of high radiation doses from 4D-CTP may cause serious health risks in stroke survivors, our research team aimed to introduce a novel image-processing technique. Our singular value decomposition (SVD)-based image-processing technique can improve image quality, first, by separating several image components using SVD and, second, by reconstructing signal component images to remove noise, thereby improving image quality. For the demonstration in this study, 20 4D-CTP dynamic images of suspected acute stroke patients were collected. Both the images that were and were not processed via the proposed method were compared. Each acquired image was objectively evaluated using contrast-to-noise and signal-to-noise ratios. The scores of the parameters assessed for the qualitative evaluation of image quality improved to an excellent rating (p < 0.05). Therefore, our SVD-based image-denoising technique improved the diagnostic value of images by improving their quality. The denoising technique and statistical evaluation can be utilized in various clinical applications to provide advanced medical services.
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Lopez-Rendon X, Stratis A, Zhang G, Coudyzer W, Develter W, Bogaerts R, Bosmans H, Zanca F. Peak skin and eye lens radiation dose from brain perfusion CT: CTDI vol and Monte Carlo based estimations. Eur J Radiol 2020; 126:108950. [PMID: 32199141 DOI: 10.1016/j.ejrad.2020.108950] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2019] [Revised: 03/04/2020] [Accepted: 03/07/2020] [Indexed: 11/16/2022]
Abstract
PURPOSE To quantify the eye lens, peak skin and brain doses associated with head CT perfusion exam by means of thermoluminescent dosimeters (TLDs) measurements in a cadaver and compare them to Monte Carlo (MC) dose estimations as well as to the CTDIvol. METHOD 18 TLDs were inserted in the brain, skin, and eye lenses of a female cadaver head, who underwent a CT brain perfusion scan using a Siemens Definition Flash. The table-toggling protocol used 80 kVp, 200 mAs, 32 × 1.2 mm collimation and 30 sequences. From the CT images, a voxel model was created. Doses were calculated with a MC framework (EGSnrc) and compared to TLD measurements. TLD measurements were also compared to the displayed CTDIvol. RESULTS The average measured doses were: 185 mGy for the eyes lenses, 107 mGy for the skin, 172 mGy for the brain and 273 mGy for the peak skin. The reported CTDIvol of 259 mGy overestimated the averaged organ doses but not the peak skin dose. MC estimated organ doses were 147 mGy for the eyes (average), 104 mGy for the skin and 178 mGy for the brain (-20 %, -3% and 4% difference respect to the TLDs measurements, respectively). CONCLUSIONS CTDIvol remains a conservative metric for average brain, skin and eyes lenses doses. For accurate eye lens and skin dose estimates MC simulations can be used. CTDIvol should be used with caution as it was of the same order of magnitude as the peak skin dose for this protocol and this particular CT scanner.
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Affiliation(s)
- X Lopez-Rendon
- Department of Imaging and Pathology, Division of Medical Physics & Quality Assessment, KU Leuven, Herestraat 49 box 7003, 3000, Leuven, Belgium.
| | - A Stratis
- Department of Imaging and Pathology, Division of Medical Physics & Quality Assessment, KU Leuven, Herestraat 49 box 7003, 3000, Leuven, Belgium
| | - G Zhang
- Department of Radiology, University Hospitals Leuven, Herestraat 49, 3000, Leuven, Belgium
| | - W Coudyzer
- Department of Radiology, University Hospitals Leuven, Herestraat 49, 3000, Leuven, Belgium
| | - W Develter
- Department of Imaging and Pathology, Division of Medical Physics & Quality Assessment, KU Leuven, Herestraat 49 box 7003, 3000, Leuven, Belgium
| | - R Bogaerts
- Laboratory of Experimental Radiotherapy, Department of Oncology, Biomedical Sciences Group, University of Leuven, Leuven, Belgium
| | - H Bosmans
- Department of Imaging and Pathology, Division of Medical Physics & Quality Assessment, KU Leuven, Herestraat 49 box 7003, 3000, Leuven, Belgium; Department of Radiology, University Hospitals Leuven, Herestraat 49, 3000, Leuven, Belgium
| | - F Zanca
- Department of Imaging and Pathology, Division of Medical Physics & Quality Assessment, KU Leuven, Herestraat 49 box 7003, 3000, Leuven, Belgium
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Amplification of Radiation-Induced Signal of LED Strip by Increasing Number of LED Chips and Using Amplifier Board. APPLIED SCIENCES-BASEL 2020. [DOI: 10.3390/app10020651] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Transducers, such as photodiodes, phototransistors, and photovoltaic cells are promising radiation detectors. However, for accurate radiation detection and dosimetry, signals that emanate from these devices have to be sufficient to facilitate accurate calibrations, i.e., assigning a quantity of radiation dose to a specific magnitude of the signal. More so, purposely fabricated for luminescence, LEDs produce significantly low signals during radiation detection applications. Therefore, this paper investigates the enhancement and augmentation of photovoltaic signals that were generated when LED strips were being exposed to diagnostic X-rays. Initially, signal amplification was achieved through increasing the effective LED active area (from 60 to 120 chips); by successively connecting LED strips. Further, signal amplification was undertaken by injecting the raw LED strip signal into an amplifier board with adjustable gains. In both the signal amplification techniques, the tube voltage (kVp), tube current-time product (mAs), and source-to-detector distance (SDD) were varied. The principal findings show that effective active area-based signal amplifications produced an overall average of 91.16% signal enhancement throughout all of the X-ray parameter variations. On the other hand, the amplifier board produced an average of 36.48% signal enhancement for the signals that were injected into it. Chip number increment-based signal amplifications had a 0.687% less coefficient of variation than amplifier board signal amplifications. The amplifier board signal amplifications were impaired by factors, such as dark currents, amplifier board maximum operational output voltage, and saturation. Therefore, future electronic signal amplification could use amplifier boards having low dark currents and high operational voltage headroom. The low-cost and simplicity that are associated with active-area amplification could be further exploited in a hybrid amplification technique with electronic amplification and scintillators.
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Comparison of Current–Voltage Response to Diagnostic X-rays of Five Light-Emitting Diode Strips. APPLIED SCIENCES-BASEL 2019. [DOI: 10.3390/app10010200] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Light-emitting diodes (LEDs) have miscellaneous applications owing to their low cost, small size, flexibility, and commercial availability. Furthermore, LEDs have dual applicability as light emitters and detectors. This study explores the current–voltage (C–V) response of LED strips exposed to diagnostic x-rays. Cold white, warm white, red, green, and blue LED strip colors were tested. Each strip consisted of 12 LED chips and was connected to a multimeter. The variable diagnostic x-ray parameters evaluated were kilovoltage peak (kVp), milliampere-seconds (mAs), and source-to-image distance (SID). The radiation dose was also measured using a dosimeter simultaneously exposed to x-rays perpendicularly incident on the strips. Lastly, the consistency of C–V responses, and any possible degradation after 1–2 months was also analyzed. Each LED strip color was ranked according to its C–V response in each of the investigated parameters. The LED strip color with the best cumulative rank across all the tested parameters was then examined for reproducibility. Our findings revealed that the C–V responses of LED strips are (a) generally low but measurable, (b) inconsistent and fluctuating as a consequence of kVp variations, (c) positively correlated to mAs, (d) negatively correlated to SID, and (e) positively correlated to dose. Overall results suggested cold white LED strip as most feasible for x-ray detection—in comparison to examined colors. Additionally, the reproducibility study using the cold white LED strip found a similar trend of C–V response to all variables except kVp. Outcomes indicate that LED strips have the potential to be exploited for detecting low dose (~0–100 mGy) diagnostic x-rays. However, future studies should be carried out to increase the low C–V signal.
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Riederer I, Bar-Ness D, Kimm MA, Si-Mohamed S, Noël PB, Rummeny EJ, Douek P, Pfeiffer D. Liquid Embolic Agents in Spectral X-Ray Photon-Counting Computed Tomography using Tantalum K-Edge Imaging. Sci Rep 2019; 9:5268. [PMID: 30918297 PMCID: PMC6437141 DOI: 10.1038/s41598-019-41737-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2018] [Accepted: 03/15/2019] [Indexed: 12/26/2022] Open
Abstract
The aim was to evaluate the potential of Spectral Photon-Counting Computed Tomography (SPCCT) to differentiate between liquid embolic agents and iodinated contrast medium by using tantalum-characteristic K-edge imaging. Tubes with a concentration series of tantalum and inserts with different concentrations of iodine were scanned with a preclinical SPCCT system. Tantalum density maps (TDM) and iodine density maps (IDM) were generated from a SPCCT acquisition. Furthermore, region-of-interest (ROI) analysis was performed within the tubes in the conventional CT, the TDM and IDM. TDM and IDM enable clear differentiation between both substances. Quantitative measurements of different tantalum concentrations match well with those of actually diluted mixtures. SPCCT allows for differentiation between tantalum and iodine and may enable for an improved follow-up diagnosis in patients after vascular occlusion therapy.
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Affiliation(s)
- Isabelle Riederer
- Department of Diagnostic and Interventional Radiology, Technical University of Munich, School of Medicine, Munich, Germany. .,Department of Diagnostic and Interventional Neuroradiology, Technical University of Munich, School of Medicine, Munich, Germany.
| | - Daniel Bar-Ness
- University Claude Bernard Lyon 1, CREATIS, CNRS UMR 5220, INSERM U1206, INSA-Lyon, France.,Department of Interventional Radiology and Cardio-vascular and Thoracic Diagnostic Imaging, Louis Pradel University Hospital, Bron, France
| | - Melanie A Kimm
- Department of Diagnostic and Interventional Radiology, Technical University of Munich, School of Medicine, Munich, Germany
| | - Salim Si-Mohamed
- University Claude Bernard Lyon 1, CREATIS, CNRS UMR 5220, INSERM U1206, INSA-Lyon, France.,Department of Interventional Radiology and Cardio-vascular and Thoracic Diagnostic Imaging, Louis Pradel University Hospital, Bron, France
| | - Peter B Noël
- Department of Diagnostic and Interventional Radiology, Technical University of Munich, School of Medicine, Munich, Germany
| | - Ernst J Rummeny
- Department of Diagnostic and Interventional Radiology, Technical University of Munich, School of Medicine, Munich, Germany
| | - Philippe Douek
- University Claude Bernard Lyon 1, CREATIS, CNRS UMR 5220, INSERM U1206, INSA-Lyon, France.,Department of Interventional Radiology and Cardio-vascular and Thoracic Diagnostic Imaging, Louis Pradel University Hospital, Bron, France
| | - Daniela Pfeiffer
- Department of Diagnostic and Interventional Radiology, Technical University of Munich, School of Medicine, Munich, Germany
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