1
|
Nishikawa Y, Fujimoto N, Kurata T, Sasou T, Yamazaki A, Ichikawa Y, Sakuma H, Dohi K. Effects of Irradiation During Computed Tomography Scanning on the Function of Implantable Cardioverter-defibrillators. J Innov Card Rhythm Manag 2024; 15:5936-5944. [PMID: 39011460 PMCID: PMC11238888 DOI: 10.19102/icrm.2024.15073] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2023] [Accepted: 02/22/2024] [Indexed: 07/17/2024] Open
Abstract
The effect of irradiation during computed tomography (CT) imaging on implantable cardioverter-defibrillators (ICDs) has not been fully evaluated in various settings. The purposes of this study were to evaluate the occurrence of electromagnetic interference (EMI) during CT irradiation in various clinically available ICDs with phantom experiments and to determine the potential risks related to irradiation during CT imaging. Five types of clinically available ICDs from five manufacturers were tested. An ICD was combined with an electrocardiogram (ECG) simulator, mounted in a chest phantom, and subjected to CT imaging. Each ICD was irradiated at the maximal power level (tube voltage, 135 kVp; tube current, 510 mA; rotation time, 1.5 s). EMI was defined as oversensing, ventricular tachycardia/ventricular fibrillation (VT/VF) detection, noise, or shock delivery during CT imaging. For ICDs in which EMI was observed, EMI was then evaluated under 144 different irradiation conditions (tube voltage [four patterns from 80-135 kVp], tube current [six patterns from 50-550 mA], and rotation time [six patterns from 0.35-1.5 s]). Testing was also performed during irradiation at the typical doses in three clinical settings and in two settings with inappropriate irradiation of ICDs due to incorrect setup. Among the five ICDs, a shock was delivered by one ICD manufactured by Medtronic (Minneapolis, MN, USA) due to oversensing during irradiation, which occurred at the maximal power level. No oversensing was observed in other ICDs. In the malfunctioned ICD, oversensing was observed in 134 of 144 irradiation patterns, even at a low power in the ICD. The VF-detection criterion was fulfilled in 20 of 134 tests and was significantly associated with tube voltage, tube current, ration time, and tube voltage × rotation time interaction. Although oversensing was observed in three clinical settings (typical chest CT, CT coronary angiography after coronary artery bypass graft, and dynamic assessment for pleural tumors) and one situation during an incorrect scan range on the chest for head perfusion CT, they were not recognized as tachycardia beats. Oversensing was observed when scans were incorrectly set over the ICD during bolus tracking of contrast-enhanced CT. Maximal power CT imaging induced VT/VF detection and shock delivery in one model of ICD placed in a chest phantom. VT/VF detection was observed when tube voltages were high and irradiation times were longer. Oversensing can occur during inappropriate CT imaging, particularly when slices are positioned over the ICD.
Collapse
Affiliation(s)
- Yusaku Nishikawa
- Department of Cardiology and Nephrology, Mie University Graduate School of Medicine, Tsu, Japan
- Department of Clinical Engineering, Faculty of Medical Engineering, Suzuka University of Medical Science, Suzuka, Japan
| | - Naoki Fujimoto
- Department of Cardiology and Nephrology, Mie University Graduate School of Medicine, Tsu, Japan
| | - Tomoaki Kurata
- Department of Radiology, Mie University Hospital, Tsu, Japan
| | - Takashi Sasou
- Department of Clinical Engineering, Mie University Hospital, Tsu, Japan
| | - Akio Yamazaki
- Department of Radiology, Mie University Hospital, Tsu, Japan
| | - Yasutaka Ichikawa
- Department of Radiology, Mie University Graduate School of Medicine, Tsu, Japan
| | - Hajime Sakuma
- Department of Radiology, Mie University Graduate School of Medicine, Tsu, Japan
| | - Kaoru Dohi
- Department of Cardiology and Nephrology, Mie University Graduate School of Medicine, Tsu, Japan
| |
Collapse
|
2
|
Loose R, Lell M. [Information, informed consent, and communication with patients]. RADIOLOGIE (HEIDELBERG, GERMANY) 2023; 63:95-98. [PMID: 36536121 DOI: 10.1007/s00117-022-01098-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 11/22/2022] [Indexed: 12/24/2022]
Abstract
The transposition of EU Directive 2013/59/Euratom into German law requires that patients be informed about the radiation risk of radiological procedures. Such information is not the same as a medical informed consent about immediate risks associated with the procedure, such as deterministic radiation damage, risks of contrast media, or complications. The sole use of X‑rays in diagnostic procedures therefore requires no informed consent in most cases.
Collapse
Affiliation(s)
- R Loose
- Institut für Medizinische Physik, Klinikum Nürnberg, Prof. Ernst Nathan Str. 1, 90419, Nürnberg, Deutschland.
| | - M Lell
- Institut für Radiologie, Neuroradiologie und Nuklearmedizin, Paracelsus Medizinische Privatuniversität, Klinikum Nürnberg, Nürnberg, Deutschland
| |
Collapse
|
3
|
A Review of Deep Learning CT Reconstruction: Concepts, Limitations, and Promise in Clinical Practice. CURRENT RADIOLOGY REPORTS 2022. [DOI: 10.1007/s40134-022-00399-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
Abstract
Abstract
Purpose of Review
Deep Learning reconstruction (DLR) is the current state-of-the-art method for CT image formation. Comparisons to existing filter back-projection, iterative, and model-based reconstructions are now available in the literature. This review summarizes the prior reconstruction methods, introduces DLR, and then reviews recent findings from DLR from a physics and clinical perspective.
Recent Findings
DLR has been shown to allow for noise magnitude reductions relative to filtered back-projection without suffering from “plastic” or “blotchy” noise texture that was found objectionable with most iterative and model-based solutions. Clinically, early reader studies have reported increases in subjective quality scores and studies have successfully implemented DLR-enabled dose reductions.
Summary
The future of CT image reconstruction is bright; deep learning methods have only started to tackle problems in this space via addressing noise reduction. Artifact mitigation and spectral applications likely be future candidates for DLR applications.
Collapse
|
4
|
Evaluation of radiation exposure for patients undergoing computed tomography perfusion procedure for acute ischemic stroke. Radiat Phys Chem Oxf Engl 1993 2022. [DOI: 10.1016/j.radphyschem.2022.110447] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
|
5
|
Abstract
The radiation dose sheet generated by the CT scanner is a form that displays important information about an examination. It functions as a road map for the examination, detailing what CT examinations were performed and what parameters were used to perform them. One essential element of the radiation dose sheet, the volume CT dose index (CTDIvol), is a commonly used radiation dose index that is displayed on most CT scanners. The CTDIvol is used for quality control and is helpful for comparing the radiation output among different protocols and different scanners. The dose-length product (DLP) is a radiation dose index that builds on the CTDIvol by incorporation of the scan length. The DLP is combined with a conversion coefficient and used to determine the effective dose from the CT examination. Determining the effective dose is a way to estimate the whole-body radiation dose, even if the CT examination is confined to a smaller part of the body. In addition to these values, other data about the study from the CT scanner manufacturer, including the tube voltage and tube current-time product, usually are displayed on CT scanners. These values are major determinants of the image quality and radiation dose. The radiation dose sheet is a useful tool for radiologists, technologists, and physicists, allowing them to comprehend the technical details of a CT examination. The authors describe the components of the radiation dose sheet, the relationships of these components with one another, and the contributions of these components to the radiation dose. ©RSNA, 2022.
Collapse
Affiliation(s)
- Anzi Zhao
- From the Department of Radiology, Northwestern Medicine, 676 N St. Clair St, Suite 800, Chicago, IL 60611
| | - Sarah Fopma
- From the Department of Radiology, Northwestern Medicine, 676 N St. Clair St, Suite 800, Chicago, IL 60611
| | - Rishi Agrawal
- From the Department of Radiology, Northwestern Medicine, 676 N St. Clair St, Suite 800, Chicago, IL 60611
| |
Collapse
|
6
|
Mahler T, Shalom E, Elovici Y, Shahar Y. A dual-layer context-based architecture for the detection of anomalous instructions sent to medical devices. Artif Intell Med 2022; 123:102229. [PMID: 34998518 DOI: 10.1016/j.artmed.2021.102229] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Revised: 08/04/2021] [Accepted: 11/30/2021] [Indexed: 11/25/2022]
Abstract
Complex medical devices are controlled by instructions sent from a host personal computer (PC) to the device. Anomalous instructions can introduce many potentially harmful threats to patients (e.g., radiation overexposure), to physical device components (e.g., manipulation of device motors), or to functionality (e.g., manipulation of medical images). Threats can occur due to cyber-attacks, human error (e.g., using the wrong protocol, or misconfiguring the protocol's parameters by a technician), or host PC software bugs. Thus, anomalous instructions might represent an intentional threat to the patient or to the device, a human error, or simply a non-optimal operation of the device. To protect medical devices, we propose a new dual-layer architecture. The architecture analyzes the instructions sent from the host PC to the physical components of the device, to detect anomalous instructions using two detection layers: (1) an unsupervised context-free (CF) layer that detects anomalies based solely on the instruction's content and inter-correlations; and (2) a supervised context-sensitive (CS) layer that detects anomalies in both the clinical objective and patient contexts using a set of supervised classifiers pre-trained for each specific context. The proposed dual-layer architecture was evaluated in the computed tomography (CT) domain, using 4842 CT instructions that we recorded, including two types of CF anomalous instructions, four types of clinical objective context instructions and four types of patient context instructions. The CF layer was evaluated using 14 unsupervised anomaly detection algorithms. The CS layer was evaluated using six supervised classification algorithms applied to each context (i.e., clinical objective or patient). Adding the second CS supervised layer to the architecture improved the overall anomaly detection performance (by improving the detection of CS anomalous instructions [when they were not also CF anomalous]) from an F1 score baseline of 72.6%, to an improved F1 score of 79.1% to 99.5% (depending on the clinical objective or patient context used). Adding, the semantics-oriented CS layer enables the detection of CS anomalies using the semantics of the device's procedure, which is not possible when using just the purely syntactic CF layer. However, adding the CS layer also introduced a somewhat increased false positive rate (FPR), and thus reduced somewhat the specificity of the overall process. We conclude that by using both the CF and CS layers, a dual-layer architecture can better detect anomalous instructions to medical devices. The increased FPR might be reduced, in the future, through the use of stronger models, and by training them on more data. The improved accuracy, and the potential capability of adding explanations to both layers, might be useful for creating decision support systems for medical device technicians.
Collapse
Affiliation(s)
- Tom Mahler
- Department of Software and Information Systems Engineering (SISE), Ben-Gurion University of the Negev, 84105 Beer Sheva, Israel.
| | - Erez Shalom
- Department of Software and Information Systems Engineering (SISE), Ben-Gurion University of the Negev, 84105 Beer Sheva, Israel
| | - Yuval Elovici
- Department of Software and Information Systems Engineering (SISE), Ben-Gurion University of the Negev, 84105 Beer Sheva, Israel
| | - Yuval Shahar
- Department of Software and Information Systems Engineering (SISE), Ben-Gurion University of the Negev, 84105 Beer Sheva, Israel
| |
Collapse
|
7
|
Ohno N, Miyati T, Sugita F, Nanbu G, Makino Y, Alperin N, Gabata T, Kobayashi S. Quantification of Regional Cerebral Blood Flow Using Diffusion Imaging With Phase Contrast. J Magn Reson Imaging 2021; 54:1678-1686. [PMID: 34021663 DOI: 10.1002/jmri.27735] [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: 03/19/2021] [Revised: 05/10/2021] [Accepted: 05/10/2021] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND The perfusion-related diffusion coefficient obtained from triexponential diffusion analysis is closely correlated with regional cerebral blood flow (rCBF), as assessed by arterial spin labeling (ASL) methods. However, this provides only a semiquantitative measure of rCBF, thereby making absolute rCBF quantification challenging. PURPOSE To obtain rCBF in a noninvasive manner using a novel diffusion imaging method with phase contrast (DPC), in which the total CBF from phase-contrast (PC) MRI was utilized to convert perfusion-related diffusion coefficients to rCBF values. STUDY TYPE Prospective. SUBJECTS Eleven healthy volunteers (nine men and two women; mean age, 23.9 years) participated in this study. FIELD STRENGTH/SEQUENCE A 3.0 T, single-shot diffusion echo-planar imaging with multiple b-values (0-3000 s/mm2 ), PC-MRI, pulsed continuous ASL, and 3D T1 -weighted fast field echo. ASSESSMENT rCBF and its correlations in the gray matter (GM) and white matter (WM) were compared between DPC and ASL methods. rCBF in the GM and WM and the GM/WM ratio were compared with the literature values obtained using [15 O]-water positron emission tomography (15 O-H2 O PET). STATISTICAL TESTS Spearman's correlation coefficient and Wilcoxon signed-rank test were used. Significance was set at P < 0.05. RESULTS A significant positive correlation between DPC and ASL in terms of rCBF was observed in GM (R = 0.9), whereas the correlation between the two methods was poor in WM (R = 0.09). The rCBF in GM and WM and the GM/WM ratio obtained using DPC were consistent with the literature values assessed using 15 O-H2 O PET. The rCBF value obtained using DPC was significantly higher in the GM and WM than that using ASL. DATA CONCLUSION DPC enabled noninvasive quantification of rCBF. EVIDENCE LEVEL 2 TECHNICAL EFFICACY: Stage 1.
Collapse
Affiliation(s)
- Naoki Ohno
- Faculty of Health Sciences, Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, Kanazawa, Japan
| | - Tosiaki Miyati
- Faculty of Health Sciences, Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, Kanazawa, Japan
| | - Fumiki Sugita
- Faculty of Health Sciences, Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, Kanazawa, Japan
| | - Genki Nanbu
- Faculty of Health Sciences, Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, Kanazawa, Japan
| | - Yuki Makino
- Department of Radiological Technology, Kanazawa University Hospital, Kanazawa, Japan
| | - Noam Alperin
- Department of Radiology, University of Miami, Miami, Florida, USA
| | - Toshifumi Gabata
- Department of Radiology, Kanazawa University Hospital, Kanazawa, Japan
| | - Satoshi Kobayashi
- Faculty of Health Sciences, Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, Kanazawa, Japan.,Department of Radiological Technology, Kanazawa University Hospital, Kanazawa, Japan.,Department of Radiology, Kanazawa University Hospital, Kanazawa, Japan
| |
Collapse
|
8
|
Li S, Zeng D, Bian Z, Li D, Zhu M, Huang J, Ma J. Learning non-local perfusion textures for high-quality computed tomography perfusion imaging. Phys Med Biol 2021; 66. [PMID: 33910178 DOI: 10.1088/1361-6560/abfc90] [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: 12/14/2020] [Accepted: 04/28/2021] [Indexed: 11/11/2022]
Abstract
Background. Computed tomography perfusion (CTP) imaging plays a critical role in the acute stroke syndrome assessment due to its widespread availability, speed of image acquisition, and relatively low cost. However, due to its repeated scanning protocol, CTP imaging involves a substantial radiation dose, which might increase potential cancer risks.Methods. In this work, we present a novel deep learning model called non-local perfusion texture learning network (NPTN) for high-quality CTP imaging at low-dose cases. Specifically, considering abundant similarities in the CTP images, i.e. latent self-similarities within the non-local region in the CTP images, we firstly search the most similar pixels from the adjacent frames within a fixed search window to obtain the non-local similarities and to construct non-local textures vector. Then, both the low-dose frame and these non-local textures from adjacent frames are fed into a convolution neural network to predict high-quality CTP images, which can help better characterize the structure details and contrast variants in the targeted CTP image rather than simply utilizing the targeted frame itself. The residual learning strategy and batch normalization are utilized to boost the performance of the convolution neural network. In the experiment, the CTP images of 31 patients with suspected stroke disease are collected to demonstrate the performance of the presented NPTN method.Results. The results show the presented NPTN method obtains superior performance compared with the competing methods. From numerical value, at all dose levels, the presented NPTN method has achieved around 3.0 dB improvement of average PSNR, an increase of around 1.4% of average SSIM, and a decrease of around 4.8% of average RMSE in the low-dose CTP reconstruction task, and also has achieved an increase of around 3.4% of average SSIM and a decrease of around 61.1% of average RMSE in the cerebral blood flow (CBF) estimation task.Conclusions. The presented NPTN method can obtain high-quality CTP images and estimate high-accuracy CBF map by characterizing more structure details and contrast variants in the CTP image and outperform the competing methods at low-dose cases.
Collapse
Affiliation(s)
- Sui Li
- School of Biomedical Engineering, Southern Medical University, Guangzhou 510515, People's Republic of China
| | - Dong Zeng
- College of Automation Science and Engineering, South China University of Technology, Guangzhou 510641, People's Republic of China.,Guangdong Artificial Intelligence and Digital Economy Laboratory (Guangzhou), Guangzhou 510335, People's Republic of China
| | - Zhaoying Bian
- School of Biomedical Engineering, Southern Medical University, Guangzhou 510515, People's Republic of China
| | - Danyang Li
- School of Biomedical Engineering, Southern Medical University, Guangzhou 510515, People's Republic of China
| | - Manman Zhu
- School of Biomedical Engineering, Southern Medical University, Guangzhou 510515, People's Republic of China
| | - Jing Huang
- School of Biomedical Engineering, Southern Medical University, Guangzhou 510515, People's Republic of China
| | - Jianhua Ma
- School of Biomedical Engineering, Southern Medical University, Guangzhou 510515, People's Republic of China.,Beijing Advanced Innovation Center for Imaging Technology, Capital Normal University, Beijing 100048, People's Republic of China.,Guangdong Artificial Intelligence and Digital Economy Laboratory (Guangzhou), Guangzhou 510335, People's Republic of China
| |
Collapse
|
9
|
Jones AK, Kisiel ME, Rong XJ, Tam AL. Validation of a method for estimating peak skin dose from CT-guided procedures. J Appl Clin Med Phys 2021; 22:224-228. [PMID: 33955655 PMCID: PMC8200428 DOI: 10.1002/acm2.13261] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022] Open
Abstract
A method for estimating peak skin dose (PSD) from CTDIvol has been published but not validated. The objective of this study was to validate this method during CT‐guided ablation procedures. Radiochromic film was calibrated and used to measure PSD. Sixty‐eight patients were enrolled in this study, and measured PSD were collected for 46 procedures. CTDIvol stratified by axial and helical scanning was used to calculate an estimate of PSD using the method [1.2 × CTDIvol(helical) + 0.6 × CTDIvol(axial)], and both calculated PSD and total CTDIvol were compared to measured PSD using paired t‐tests on the log‐transformed data and Bland‐Altman analysis. Calculated PSD were significantly different from measured PSD (P < 0.0001, bias, 18.3%, 95% limits of agreement, −63.0% to 26.4%). Measured PSD were not significantly different from total CTDIvol (P = 0.27, bias, 3.97%, 95% limits of agreement, −51.6% to 43.7%). Considering that CTDIvol is reported on the console of all CT scanners, is not stratified by axial and helical scanning modes, and is immediately available to the operator during CT‐guided interventional procedures, it may be reasonable to use the scanner‐reported CTDIvol as an indicator of PSD during CT‐guided procedures. However, further validation is required for other models of CT scanner.
Collapse
Affiliation(s)
- A Kyle Jones
- Department of Imaging Physics, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Meghan E Kisiel
- Department of Imaging Physics, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - X John Rong
- Department of Imaging Physics, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Alda L Tam
- Department of Interventional Radiology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| |
Collapse
|
10
|
Valtchinov VI, Siegelman J, Zhai BK, Khorasani R, Sodickson A. One size does not fit all: Factors associated with increased frequency of radiation overexposure alerts based on fixed-alert thresholds. Phys Med 2021; 82:79-86. [PMID: 33601164 DOI: 10.1016/j.ejmp.2021.02.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Revised: 01/22/2021] [Accepted: 02/06/2021] [Indexed: 10/22/2022] Open
Abstract
OBJECTIVES Quantify the expected rate of CT radiation dose alerts for three body regions using accepted radiation dose benchmarks and assess key determinants of alert frequency. METHODS This IRB-approved retrospective cohort study evaluated consecutive CT examinations performed between July and December 2013 within an academic medical system. CTDIvol x-ray tube output metrics were compared to the body-region-specific benchmark levels, Achievable Doses (AD), Diagnostic Reference Levels (DRL), and Dose Notification Values (DNV). A logistic regression model for the simulated alerts was fit as a function of the independent predictors: scanner, body region, gender, weight, and age. RESULTS For 17,000 exams, the proportion of events triggering alerts increased with patient weight. Significant covariates were scanner, body region, patient weight and patient age (all p < 0.0001). Odds of alert generation for the AD, DRL, and DNV benchmarks increased by 7.6%, 6.6% and 2.9% per kilogram, respectively, and by 0.8%, 1.1% and -2.7% per year of age (all p < 0.0001). Compared to the most highly optimized scanner, odds of alert generation varied by a factor of 595 for AD, 1126 for DRL, and 13 for DNV. CONCLUSION Alert frequency was significantly correlated with weight, age, body region and scanner. Controllable factors include scanner functionality and associated protocol optimization. Patient factors driving alert frequency are predominantly weight, and to a lesser degree, age. Size-agnostic fixed dose thresholds can frequently produce false positive alerts in appropriately performed exams of large patients, while missing opportunities to identify outlier scans of higher-than-expected dose in small patients.
Collapse
Affiliation(s)
- Vladimir I Valtchinov
- Center for Evidence-Based Imaging (CEBI), Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA; Department of Radiology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA; Department of Biomedical Informatics, Harvard Medical School, Boston, MA, USA
| | - Jenifer Siegelman
- Department of Radiology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA; Takeda Pharmaceuticals, Boston, MA, USA
| | - Bingxue K Zhai
- Department of Radiology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA
| | - Ramin Khorasani
- Center for Evidence-Based Imaging (CEBI), Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA; Department of Radiology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA
| | - Aaron Sodickson
- Center for Evidence-Based Imaging (CEBI), Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA; Department of Radiology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA
| |
Collapse
|
11
|
Pasqual E, Boussin F, Bazyka D, Nordenskjold A, Yamada M, Ozasa K, Pazzaglia S, Roy L, Thierry-Chef I, de Vathaire F, Benotmane MA, Cardis E. Cognitive effects of low dose of ionizing radiation - Lessons learned and research gaps from epidemiological and biological studies. ENVIRONMENT INTERNATIONAL 2021; 147:106295. [PMID: 33341586 DOI: 10.1016/j.envint.2020.106295] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 10/02/2020] [Accepted: 10/20/2020] [Indexed: 06/12/2023]
Abstract
The last decades have seen increased concern about the possible effects of low to moderate doses of ionizing radiation (IR) exposure on cognitive function. An interdisciplinary group of experts (biologists, epidemiologists, dosimetrists and clinicians) in this field gathered together in the framework of the European MELODI workshop on non-cancer effects of IR to summarise the state of knowledge on the topic and elaborate research recommendations for future studies in this area. Overall, there is evidence of cognitive effects from low IR doses both from biology and epidemiology, though a better characterization of effects and understanding of mechanisms is needed. There is a need to better describe the specific cognitive function or diseases that may be affected by radiation exposure. Such cognitive deficit characterization should consider the human life span, as effects might differ with age at exposure and at outcome assessment. Measurements of biomarkers, including imaging, will likely help our understanding on the mechanism of cognitive-related radiation induced deficit. The identification of loci of individual genetic susceptibility and the study of gene expression may help identify individuals at higher risk. The mechanisms behind the radiation induced cognitive effects are not clear and are likely to involve several biological pathways and different cell types. Well conducted research in large epidemiological cohorts and experimental studies in appropriate animal models are needed to improve the understanding of radiation-induced cognitive effects. Results may then be translated into recommendations for clinical radiation oncology and imaging decision making processes.
Collapse
Affiliation(s)
- Elisa Pasqual
- Barcelona Institute for Global Health (ISGlobal), Campus Mar, Barcelona Biomedical Research Park (PRBB), Dr Aiguader 88, 08003 Barcelona, Spain; University Pompeu Fabra, Barcelona, Spain; Consortium for Biomedical Research in Epidemiology & Public Health (CIBERESP), Carlos III Institute of Health, Madrid, Spain.
| | - François Boussin
- Université de Paris and Université Paris-Saclay, Inserm, LRP/iRCM/IBFJ CEA, UMR Stabilité Génétique Cellules Souches et Radiations, F-92265 Fontenay-aux-Roses, France
| | - Dimitry Bazyka
- National Research Center for Radiation Medicine, 53 Illenko str., Kyiv, Ukraine
| | - Arvid Nordenskjold
- Department of Clinical Neuroscience, Division of Neurology, Karolinska Institutet, Stockholm, Sweden
| | - Michiko Yamada
- Department of Clinical Studies, Radiation Effects Research Foundation, Hiroshima, Japan
| | - Kotaro Ozasa
- Department of Epidemiology, Radiation Effects Research Foundation, Hiroshima, Japan
| | - Simonetta Pazzaglia
- Laboratory of Biomedical Technologies, ENEA CR-Casaccia, Via Anguillarese 301, 00123 Rome, Italy
| | - Laurence Roy
- Department for Research on the Biological and Health Effects of Ionising Radiation. Institut of Radiation Protection and Nuclear Safety (IRSN), Fontenay-aux-Roses, France
| | - Isabelle Thierry-Chef
- Barcelona Institute for Global Health (ISGlobal), Campus Mar, Barcelona Biomedical Research Park (PRBB), Dr Aiguader 88, 08003 Barcelona, Spain; University Pompeu Fabra, Barcelona, Spain; Consortium for Biomedical Research in Epidemiology & Public Health (CIBERESP), Carlos III Institute of Health, Madrid, Spain
| | - Florent de Vathaire
- Radiation Epidemiology Teams, INSERM Unit 1018, University Paris Saclay, Gustave Roussy, 94800 Villejuif, France
| | | | - Elisabeth Cardis
- Barcelona Institute for Global Health (ISGlobal), Campus Mar, Barcelona Biomedical Research Park (PRBB), Dr Aiguader 88, 08003 Barcelona, Spain; University Pompeu Fabra, Barcelona, Spain; Consortium for Biomedical Research in Epidemiology & Public Health (CIBERESP), Carlos III Institute of Health, Madrid, Spain
| |
Collapse
|
12
|
Zhang Y, Peng J, Zeng D, Xie Q, Li S, Bian Z, Wang Y, Zhang Y, Zhao Q, Zhang H, Liang Z, Lu H, Meng D, Ma J. Contrast-Medium Anisotropy-Aware Tensor Total Variation Model for Robust Cerebral Perfusion CT Reconstruction with Low-Dose Scans. IEEE TRANSACTIONS ON COMPUTATIONAL IMAGING 2020; 6:1375-1388. [PMID: 33313342 PMCID: PMC7731921 DOI: 10.1109/tci.2020.3023598] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Perfusion computed tomography (PCT) is critical in detecting cerebral ischemic lesions. PCT examination with low-dose scans can effectively reduce radiation exposure to patients at the cost of degraded images with severe noise and artifacts. Tensor total variation (TTV) models are powerful tools that can encode the regional continuous structures underlying a PCT object. In a TTV model, the sparsity structures of the contrast-medium concentration (CMC) across PCT frames are assumed to be isotropic with identical and independent distribution. However, this assumption is inconsistent with practical PCT tasks wherein the sparsity has evident variations and correlations. Such modeling deviation hampers the performance of TTV-based PCT reconstructions. To address this issue, we developed a novel contrast-medium anisotropy-aware tensor total variation (CMAA-TTV) model to describe the intrinsic anisotropy sparsity of the CMC in PCT imaging tasks. Instead of directly on the difference matrices, the CMAA-TTV model characterizes sparsity on a low-rank subspace of the difference matrices which are calculated from the input data adaptively, thus naturally encoding the intrinsic variant and correlated anisotropy sparsity structures of the CMC. We further proposed a robust and efficient PCT reconstruction algorithm to improve low-dose PCT reconstruction performance using the CMAA-TTV model. Experimental studies using a digital brain perfusion phantom, patient data with low-dose simulation and clinical patient data were performed to validate the effectiveness of the presented algorithm. The results demonstrate that the CMAA-TTV algorithm can achieve noticeable improvements over state-of-the-art methods in low-dose PCT reconstruction tasks.
Collapse
Affiliation(s)
- Yuanke Zhang
- School of Biomedical Engineering, Southern Medical University, Guangzhou 510515, China, and also with the School of Information Science and Engineering, Qufu Normal University, Rizhao 276826, China
| | - Jiangjun Peng
- School of Mathematics and Statistics, Xi'an Jiaotong University, Xi'an 710049, China
| | - Dong Zeng
- School of Biomedical Engineering, Southern Medical University, Guangzhou 510515, China
| | - Qi Xie
- School of Mathematics and Statistics, Xi'an Jiaotong University, Xi'an 710049, China
| | - Sui Li
- School of Biomedical Engineering, Southern Medical University, Guangzhou 510515, China
| | - Zhaoying Bian
- School of Biomedical Engineering, Southern Medical University, Guangzhou 510515, China
| | - Yongbo Wang
- School of Biomedical Engineering, Southern Medical University, Guangzhou 510515, China
| | - Yong Zhang
- School of Mathematics and Statistics, Xi'an Jiaotong University, Xi'an 710049, China
| | - Qian Zhao
- School of Mathematics and Statistics, Xi'an Jiaotong University, Xi'an 710049, China
| | - Hao Zhang
- Department of Radiation Oncology, Stanford University, Stanford, CA 94305, USA
| | - Zhengrong Liang
- Departments of Radiology and Biomedical Engineering, State University of New York at Stony Brook, NY 11794, USA
| | - Hongbing Lu
- School of Biomedical Engineering, Fourth Military Medical University, Xi'an 710032, China
| | - Deyu Meng
- School of Mathematics and Statistics, Xi'an Jiaotong University, Xi'an 710049, China
| | - Jianhua Ma
- School of Biomedical Engineering, Southern Medical University, Guangzhou 510515, China
| |
Collapse
|
13
|
Sengupta B, Medlin D, Sprunk M, Napolitano J, D'Avanzo J, Ran Zheng X, Dean D, Takacs E. X-ray cabinet to deliver highly characterized low-dose soft x-ray radiation to biological samples. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2020; 91:034104. [PMID: 32259947 DOI: 10.1063/1.5109233] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/07/2019] [Accepted: 02/29/2020] [Indexed: 06/11/2023]
Abstract
We have designed, built, and tested a climate-controlled, radiation-shielded incubator cabinet for the purpose of analyzing the effects of low-dose x-ray radiation on biological tissues and cell cultures. Bremsstrahlung x rays incident on exchangeable fluorescence plates produce strong, quasi-monochromatic radiation directed toward a small container of biological samples. The x-ray source, sample, and detector are enclosed in an incubator-maintaining the optimal environment for biological samples to increase longevity to a maximum of 72 h. To demonstrate the capabilities of the setup, an example experiment is presented. Rat vascular smooth muscle cell growth was observed after irradiation with characteristic x rays of iron, copper, and calcium to impart doses of 2 mGy each. Cultures show significant spectrum dependent increases in cell number over controls at 48 h after irradiation. The experiment lends credence to the efficacy of the apparatus and shows promise for future low-dose bio-radiation studies.
Collapse
Affiliation(s)
- Bishwambhar Sengupta
- Department of Physics and Astronomy, Clemson University, Clemson, South Carolina 29634, USA
| | - Donald Medlin
- Department of Physics and Astronomy, Clemson University, Clemson, South Carolina 29634, USA
| | - Michael Sprunk
- Department of Mechanical Engineering, Clemson University, Clemson, South Carolina 29634, USA
| | - Justin Napolitano
- Department of Bioengineering, Clemson University, Clemson, South Carolina 29634, USA
| | - Jaclyn D'Avanzo
- Department of Physics and Astronomy, Clemson University, Clemson, South Carolina 29634, USA
| | - Xiao Ran Zheng
- Department of Physics and Astronomy, Clemson University, Clemson, South Carolina 29634, USA
| | - Delphine Dean
- Department of Bioengineering, Clemson University, Clemson, South Carolina 29634, USA
| | - Endre Takacs
- Department of Physics and Astronomy, Clemson University, Clemson, South Carolina 29634, USA
| |
Collapse
|
14
|
Mahler T, Shalom E, Elovici Y, Shahar Y. A Dual-Layer Architecture for the Protection of Medical Devices from Anomalous Instructions. Artif Intell Med 2020. [DOI: 10.1007/978-3-030-59137-3_25] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
|
15
|
Li K, Strother CM, Chen GH. Statistical properties of cerebral CT perfusion imaging systems. Part I. Cerebral blood volume maps generated from nondeconvolution-based systems. Med Phys 2019; 46:4869-4880. [PMID: 31487396 DOI: 10.1002/mp.13806] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2019] [Revised: 06/24/2019] [Accepted: 08/27/2019] [Indexed: 11/09/2022] Open
Abstract
PURPOSE The development and clinical employment of a computed tomography (CT) imaging system benefit from a thorough understanding of the statistical properties of the output images; cerebral CT perfusion (CTP) imaging system is no exception. A series of articles will present statistical properties of CTP systems and the dependence of these properties on system parameters. This Part I paper focuses on the signal and noise properties of cerebral blood volume (CBV) maps calculated using a nondeconvolution-based method. METHODS The CBV imaging chain was decomposed into a cascade of subimaging stages, which facilitated the derivation of analytical models for the probability density function, mean value, and noise variance of CBV. These models directly take CTP source image acquisition, reconstruction, and postprocessing parameters as inputs. Both numerical simulations and in vivo canine experiments were performed to validate these models. RESULTS The noise variance of CBV is linearly related to the noise variance of source images and is strongly influenced by the noise variance of the baseline images. Uniformly partitioning the total radiation dose budget across all time frames was found to be suboptimal, and an optimal dose partition method was derived to minimize CBV noise. Results of the numerical simulation and animal studies validated the derived statistical properties of CBV. CONCLUSIONS The statistical properties of CBV imaging systems can be accurately modeled by extending the linear CT systems theory. Based on the statistical model, several key signal and noise characteristics of CBV were identified and an optimal dose partition method was developed to improve the image quality of CBV.
Collapse
Affiliation(s)
- Ke Li
- Department of Medical Physics, University of Wisconsin-Madison, 1111 Highland Avenue, Madison, WI, 53705, USA.,Department of Radiology, University of Wisconsin-Madison, 600 Highland Avenue, Madison, WI, 53792, USA
| | - Charles M Strother
- Department of Radiology, University of Wisconsin-Madison, 600 Highland Avenue, Madison, WI, 53792, USA
| | - Guang-Hong Chen
- Department of Medical Physics, University of Wisconsin-Madison, 1111 Highland Avenue, Madison, WI, 53705, USA.,Department of Radiology, University of Wisconsin-Madison, 600 Highland Avenue, Madison, WI, 53792, USA
| |
Collapse
|
16
|
Nadarevic T, Giljaca V, Colli A, Fraquelli M, Casazza G, Miletic D, Štimac D. Computed tomography for the diagnosis of hepatocellular carcinoma in chronic advanced liver disease. THE COCHRANE DATABASE OF SYSTEMATIC REVIEWS 2019. [DOI: 10.1002/14651858.cd013362] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- Tin Nadarevic
- Clinical Hospital Centre Rijeka; Department of Radiology; Kresimirova 42 Rijeka Croatia 51000
| | - Vanja Giljaca
- Heart of England NHS Foundation Trust, Birmingham Heartlands Hospital; Directorate of Surgery, Department of Gastroenterology; Bordesley Green East Birmingham UK B9 5SS
| | - Agostino Colli
- A Manzoni Hospital ASST Lecco; Department of Internal Medicine; Via dell'Eremo, 9/11 Lecco Italy 23900
| | - Mirella Fraquelli
- Fondazione IRCCS Cà Granda - Ospedale Maggiore Policlinico, Department of Pathophysiology and Transplantation, Università degli Studi di Milano; Gastroenterology and Endoscopy Unit; Via F. Sforza, 35 Milan Italy 20122
| | - Giovanni Casazza
- Università degli Studi di Milano; Dipartimento di Scienze Biomediche e Cliniche "L. Sacco"; via GB Grassi 74 Milan Italy 20157
| | - Damir Miletic
- Clinical Hospital Centre Rijeka; Department of Radiology; Kresimirova 42 Rijeka Croatia 51000
| | - Davor Štimac
- Clinical Hospital Centre Rijeka; Department of Gastroenterology; Kresimirova 42 Rijeka Croatia 51000
| |
Collapse
|
17
|
Xiao Y, Liu P, Liang Y, Stolte S, Sanelli P, Gupta A, Ivanidze J, Fang R. STIR-Net: Deep Spatial-Temporal Image Restoration Net for Radiation Reduction in CT Perfusion. Front Neurol 2019; 10:647. [PMID: 31297079 PMCID: PMC6607281 DOI: 10.3389/fneur.2019.00647] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2018] [Accepted: 06/03/2019] [Indexed: 02/04/2023] Open
Abstract
Computed Tomography Perfusion (CTP) imaging is a cost-effective and fast approach to provide diagnostic images for acute stroke treatment. Its cine scanning mode allows the visualization of anatomic brain structures and blood flow; however, it requires contrast agent injection and continuous CT scanning over an extended time. In fact, the accumulative radiation dose to patients will increase health risks such as skin irritation, hair loss, cataract formation, and even cancer. Solutions for reducing radiation exposure include reducing the tube current and/or shortening the X-ray radiation exposure time. However, images scanned at lower tube currents are usually accompanied by higher levels of noise and artifacts. On the other hand, shorter X-ray radiation exposure time with longer scanning intervals will lead to image information that is insufficient to capture the blood flow dynamics between frames. Thus, it is critical for us to seek a solution that can preserve the image quality when the tube current and the temporal frequency are both low. We propose STIR-Net in this paper, an end-to-end spatial-temporal convolutional neural network structure, which exploits multi-directional automatic feature extraction and image reconstruction schema to recover high-quality CT slices effectively. With the inputs of low-dose and low-resolution patches at different cross-sections of the spatio-temporal data, STIR-Net blends the features from both spatial and temporal domains to reconstruct high-quality CT volumes. In this study, we finalize extensive experiments to appraise the image restoration performance at different levels of tube current and spatial and temporal resolution scales.The results demonstrate the capability of our STIR-Net to restore high-quality scans at as low as 11% of absorbed radiation dose of the current imaging protocol, yielding an average of 10% improvement for perfusion maps compared to the patch-based log likelihood method.
Collapse
Affiliation(s)
- Yao Xiao
- J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, Gainesville, FL, United States
| | - Peng Liu
- J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, Gainesville, FL, United States
| | - Yun Liang
- J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, Gainesville, FL, United States
| | - Skylar Stolte
- J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, Gainesville, FL, United States
| | - Pina Sanelli
- Department of Radiology, Weill Cornell Medical College, New York, NY, United States
- Imaging Clinical Effectiveness and Outcomes Research, Department of Radiology, Northwell Health, Manhasset, NY, United States
- Donald and Barbara Zucker School of Medicine at Hofstra/Northwell, Hempstead, NY, United States
- Center for Health Innovations and Outcomes Research, Feinstein Institute for Medical Research, Manhasset, NY, United States
| | - Ajay Gupta
- Department of Radiology, Weill Cornell Medical College, New York, NY, United States
| | - Jana Ivanidze
- Department of Radiology, Weill Cornell Medical College, New York, NY, United States
| | - Ruogu Fang
- J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, Gainesville, FL, United States
| |
Collapse
|
18
|
Karwacki GM, Vögele S, Blackham KA. Dose reduction in perfusion CT in stroke patients by lowering scan frequency does not affect automatically calculated infarct core volumes. J Neuroradiol 2019; 46:351-358. [PMID: 31034899 DOI: 10.1016/j.neurad.2019.04.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2018] [Revised: 04/04/2019] [Accepted: 04/09/2019] [Indexed: 10/26/2022]
Abstract
BACKGROUND AND PURPOSE CT Perfusion technique (CTP) is a quantitative, easily performed, accepted and reliable method for detection of ischemic brain changes. Based on calculated parameters, the size of ischemic penumbra and irreversibly damaged infarct core can be determined which helps guide treatment decisions. However, due to the dynamic nature of the CTP study, it is dose intensive. This study determines the consequences of retrospectively reducing the number of scans in the dynamic acquisition by half on the volume of the automatically calculated infarct core (non-viable tissue) and penumbra (tissue at risk) volumes. Our hypothesis was that equivalent volumetric information could be obtained at a substantial dose savings. MATERIALS AND METHODS Fifty one consecutive patients with occlusion of M1 and/or M2 segment of the middle cerebral artery and ischemic stroke proven by follow-up MRI were included. CTP scans were first analyzed in a standard fashion and automatically generated volumes measured in milliliters were recorded in a database. A second analysis was conducted after removing every second data acquisition from the sequential CTP scans. Automatic volume measurements were repeated, recorded and compared to the initial values obtained using the full dataset. RESULTS The two CTP protocols were statistically equivalent pertaining to automatic infarct core volume calculation but a case-by-case analysis revealed substantial overestimation in some cases. CONCLUSION Reduction of radiation exposure in CTP without objective loss of accuracy of automatically calculated infarct core volume is feasible but might lead to clinically relevant infarct core overestimation in individual cases.
Collapse
Affiliation(s)
- Grzegorz Marek Karwacki
- University Hospital Basel, University of Basel, clinic of radiology and nuclear medicine, Basel, Switzerland.
| | - Stephan Vögele
- University Hospital Basel, University of Basel, clinic of radiology and nuclear medicine, Basel, Switzerland
| | - Kristine Ann Blackham
- University Hospital Basel, University of Basel, clinic of radiology and nuclear medicine, Basel, Switzerland
| |
Collapse
|
19
|
Ferrero A, Takahashi N, Vrtiska TJ, Krambeck AE, Lieske JC, McCollough CH. Understanding, justifying, and optimizing radiation exposure for CT imaging in nephrourology. Nat Rev Urol 2019; 16:231-244. [PMID: 30728476 PMCID: PMC6447446 DOI: 10.1038/s41585-019-0148-8] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
An estimated 4-5 million CT scans are performed in the USA every year to investigate nephrourological diseases such as urinary stones and renal masses. Despite the clinical benefits of CT imaging, concerns remain regarding the potential risks associated with exposure to ionizing radiation. To assess the potential risk of harmful biological effects from exposure to ionizing radiation, understanding the mechanisms by which radiation damage and repair occur is essential. Although radiation level and cancer risk follow a linear association at high doses, no strong relationship is apparent below 100 mSv, the doses used in diagnostic imaging. Furthermore, the small theoretical increase in risk of cancer incidence must be considered in the context of the clinical benefit derived from a medically indicated CT and the likelihood of cancer occurrence in the general population. Elimination of unnecessary imaging is the most important method to reduce imaging-related radiation; however, technical aspects of medically justified imaging should also be optimized, such that the required diagnostic information is retained while minimizing the dose of radiation. Despite intensive study, evidence to prove an increased cancer risk associated with radiation doses below ~100 mSv is lacking; however, concerns about ionizing radiation in medical imaging remain and can affect patient care. Overall, the principles of justification and optimization must remain the basis of clinical decision-making regarding the use of ionizing radiation in medicine.
Collapse
Affiliation(s)
- Andrea Ferrero
- Department of Radiology, Mayo Clinic, Rochester, MN, USA
| | | | | | - Amy E Krambeck
- Department of Urology, Indiana University School of Medicine, Indianapolis, IN, USA
| | - John C Lieske
- Department of Nephrology and Hypertension, Mayo Clinic, Rochester, MN, USA
| | | |
Collapse
|
20
|
Kadimesetty VS, Gutta S, Ganapathy S, Yalavarthy PK. Convolutional Neural Network-Based Robust Denoising of Low-Dose Computed Tomography Perfusion Maps. IEEE TRANSACTIONS ON RADIATION AND PLASMA MEDICAL SCIENCES 2019. [DOI: 10.1109/trpms.2018.2860788] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
|
21
|
Wang A, Maslowski A, Wareing T, Star-Lack J, Schmidt TG. A fast, linear Boltzmann transport equation solver for computed tomography dose calculation (Acuros CTD). Med Phys 2018; 46:925-933. [PMID: 30471131 DOI: 10.1002/mp.13305] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2018] [Revised: 10/28/2018] [Accepted: 11/15/2018] [Indexed: 02/05/2023] Open
Abstract
PURPOSE To improve dose reporting of CT scans, patient-specific organ doses are highly desired. However, estimating the dose distribution in a fast and accurate manner remains challenging, despite advances in Monte Carlo methods. In this work, we present an alternative method that deterministically solves the linear Boltzmann transport equation (LBTE), which governs the behavior of x-ray photon transport through an object. METHODS Our deterministic solver for CT dose (Acuros CTD) is based on the same approach used to estimate scatter in projection images of a CT scan (Acuros CTS). A deterministic method is used to compute photon fluence within the object, which is then converted to deposited energy by multiplying by known, material-specific conversion factors. To benchmark Acuros CTD, we used the AAPM Task Group 195 test for CT dose, which models an axial, fan beam scan (10 mm thick beam) and calculates energy deposited in each organ of an anthropomorphic phantom. We also validated our own Monte Carlo implementation of Geant4 to use as a reference to compare Acuros against for other common geometries like an axial, cone beam scan (160 mm thick beam) and a helical scan (40 mm thick beam with table motion for a pitch of 1). RESULTS For the fan beam scan, Acuros CTD accurately estimated organ dose, with a maximum error of 2.7% and RMSE of 1.4% when excluding organs with <0.1% of the total energy deposited. The cone beam and helical scans yielded similar levels of accuracy compared to Geant4. Increasing the number of source positions beyond 18 or decreasing the voxel size below 5 × 5 × 5 mm3 provided marginal improvement to the accuracy for the cone beam scan but came at the expense of increased run time. Across the different scan geometries, run time of Acuros CTD ranged from 8 to 23 s. CONCLUSIONS In this digital phantom study, a deterministic LBTE solver was capable of fast and accurate organ dose estimates.
Collapse
Affiliation(s)
- Adam Wang
- Varian Medical Systems, Palo Alto, CA, 94304, USA
| | | | - Todd Wareing
- Varian Medical Systems, Palo Alto, CA, 94304, USA
| | | | - Taly Gilat Schmidt
- Department of Biomedical Engineering, Marquette University, Milwaukee, WI, 53201, USA
| |
Collapse
|
22
|
Medlen KP, Leahy NA, Greene-Donnelly K, Fleishon HB, Jiménez P. Better use of available radiology resources for women's health in Latin America and the Caribbean. Rev Panam Salud Publica 2018; 42:e115. [PMID: 31093143 PMCID: PMC6385628 DOI: 10.26633/rpsp.2018.115] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2018] [Accepted: 05/07/2018] [Indexed: 11/26/2022] Open
Abstract
Despite the United Nations Millennium Development Goals and the 2030 Sustainable Development Goals, women in numerous countries still face many challenges in obtaining good-quality health care. For example, various nations in Latin America and the Caribbean (LAC) do not have access to complex radiology technologies. However, conventional radiography, ultrasound, mammography, and computed tomography are available and can be used to address such women's health concerns as breast and cervical cancers, postpartum bleeding, and tuberculosis. LAC countries face additional difficulties in radiology services with respect to quality human resources, quality assurance programs, standardization, and functioning of diagnostic imaging units. These deficiencies affect the quality of the services rendered. Appropriate measures must be implemented to produce quality services and quality images and to reduce adverse events. These steps will ensure better outcomes and consequently reduce mortality and morbidity.
Collapse
Affiliation(s)
- Kayiba Peggy Medlen
- Department of Health Systems and Services/Unit of Medicines and Health Technologies, Radiological Health Program, Pan American Health Organization, Washington, D.C., United States of America
| | | | | | - Howard Bruce Fleishon
- Emory St. Joseph's Hospital, Department of Radiology, Atlanta, Georgia, United States of America
| | - Pablo Jiménez
- Department of Health Systems and Services/Unit of Medicines and Health Technologies, Radiological Health Program, Pan American Health Organization, Washington, D.C., United States of America
| |
Collapse
|
23
|
Afat S, Brockmann C, Nikoubashman O, Müller M, Thierfelder KM, Brockmann MA, Nikolaou K, Wiesmann M, Kim JH, Othman AE. Diagnostic Accuracy of Simulated Low-Dose Perfusion CT to Detect Cerebral Perfusion Impairment after Aneurysmal Subarachnoid Hemorrhage: A Retrospective Analysis. Radiology 2018; 287:643-650. [PMID: 29309735 DOI: 10.1148/radiol.2017162707] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Purpose To evaluate diagnostic accuracy of low-dose volume perfusion (VP) computed tomography (CT) compared with original VP CT regarding the detection of cerebral perfusion impairment after aneurysmal subarachnoid hemorrhage. Materials and Methods In this retrospective study, 85 patients (mean age, 59.6 years; 62 women) with aneurysmal subarachnoid hemorrhage and who were suspected of having cerebral vasospasm at unenhanced CT and VP CT (tube voltage, 80 kVp; tube current-time product, 180 mAs) were included, 37 of whom underwent digital subtraction angiography (DSA) within 6 hours. Low-dose VP CT data sets at tube current-time product of 72 mAs were retrospectively generated by validated realistic simulation. Perfusion maps were generated from both data sets and reviewed by two neuroradiologists for overall image quality, diagnostic confidence and presence and/or severity of perfusion impairment indicating vasospasm. An interventional neuroradiologist evaluated 16 vascular segments at DSA. Diagnostic accuracy of low-dose VP CT was calculated with original VP CT as reference standard. Agreement between findings of both data sets was assessed by using weighted Cohen κ and findings were correlated with DSA by using Spearman correlation. After quantitative volumetric analysis, lesion volumes were compared on both VP CT data sets. Results Low-dose VP CT yielded good ratings of image quality and diagnostic confidence and classified all patients correctly with high diagnostic accuracy (sensitivity, 99.0%; specificity, 99.5%) without significant differences regarding presence and/or severity of perfusion impairment between original and low-dose data sets (Z = -0.447; P = .655). Findings of both data sets correlated significantly with DSA (original, r = 0.671; low dose, r = 0.667). Lesion volume was comparable for both data sets (relative difference, 5.9% ± 5.1 [range, 0.2%-25.0%; median, 4.0%]) with strong correlation (r = 0.955). Conclusion The results suggest that radiation dose reduction to 40% of original dose levels (tube current-time product, 72 mAs) may be performed in VP CT imaging of patients with aneurysmal subarachnoid hemorrhage without compromising the diagnostic accuracy regarding detection of cerebral perfusion impairment indicating vasospasm. © RSNA, 2018 Online supplemental material is available for this article.
Collapse
Affiliation(s)
- Saif Afat
- From the Department of Diagnostic and Interventional Neuroradiology, RWTH Aachen University, Aachen, Germany (S.A., O.N., M.M., M.W., A.E.O.); Department for Diagnostic and Interventional Radiology, Eberhard Karls University Tuebingen, University Hospital Tuebingen, Hoppe-Seyler-Strasse 3, 72076 Tübingen, Germany (S.A., K.N., A.E.O.); Department of Neuroradiology, University Hospital Mainz, Mainz, Germany (M.A.B., C.B.); Institute for Clinical Radiology, Ludwig-Maximilian-University Hospital Munich, Munich, Germany (K.M.T.); Department of Transdisciplinary Studies, Graduate School of Convergence Science and Technology, Seoul National University, Suwon, South Korea (J.H.K.); Department of Radiology, Seoul National University College of Medicine, Seoul, South Korea (J.H.K.); and Center for Medical-IT Convergence Technology Research, Advanced Institute of Convergence Technology, Suwon, South Korea (J.H.K.)
| | - Carolin Brockmann
- From the Department of Diagnostic and Interventional Neuroradiology, RWTH Aachen University, Aachen, Germany (S.A., O.N., M.M., M.W., A.E.O.); Department for Diagnostic and Interventional Radiology, Eberhard Karls University Tuebingen, University Hospital Tuebingen, Hoppe-Seyler-Strasse 3, 72076 Tübingen, Germany (S.A., K.N., A.E.O.); Department of Neuroradiology, University Hospital Mainz, Mainz, Germany (M.A.B., C.B.); Institute for Clinical Radiology, Ludwig-Maximilian-University Hospital Munich, Munich, Germany (K.M.T.); Department of Transdisciplinary Studies, Graduate School of Convergence Science and Technology, Seoul National University, Suwon, South Korea (J.H.K.); Department of Radiology, Seoul National University College of Medicine, Seoul, South Korea (J.H.K.); and Center for Medical-IT Convergence Technology Research, Advanced Institute of Convergence Technology, Suwon, South Korea (J.H.K.)
| | - Omid Nikoubashman
- From the Department of Diagnostic and Interventional Neuroradiology, RWTH Aachen University, Aachen, Germany (S.A., O.N., M.M., M.W., A.E.O.); Department for Diagnostic and Interventional Radiology, Eberhard Karls University Tuebingen, University Hospital Tuebingen, Hoppe-Seyler-Strasse 3, 72076 Tübingen, Germany (S.A., K.N., A.E.O.); Department of Neuroradiology, University Hospital Mainz, Mainz, Germany (M.A.B., C.B.); Institute for Clinical Radiology, Ludwig-Maximilian-University Hospital Munich, Munich, Germany (K.M.T.); Department of Transdisciplinary Studies, Graduate School of Convergence Science and Technology, Seoul National University, Suwon, South Korea (J.H.K.); Department of Radiology, Seoul National University College of Medicine, Seoul, South Korea (J.H.K.); and Center for Medical-IT Convergence Technology Research, Advanced Institute of Convergence Technology, Suwon, South Korea (J.H.K.)
| | - Marguerite Müller
- From the Department of Diagnostic and Interventional Neuroradiology, RWTH Aachen University, Aachen, Germany (S.A., O.N., M.M., M.W., A.E.O.); Department for Diagnostic and Interventional Radiology, Eberhard Karls University Tuebingen, University Hospital Tuebingen, Hoppe-Seyler-Strasse 3, 72076 Tübingen, Germany (S.A., K.N., A.E.O.); Department of Neuroradiology, University Hospital Mainz, Mainz, Germany (M.A.B., C.B.); Institute for Clinical Radiology, Ludwig-Maximilian-University Hospital Munich, Munich, Germany (K.M.T.); Department of Transdisciplinary Studies, Graduate School of Convergence Science and Technology, Seoul National University, Suwon, South Korea (J.H.K.); Department of Radiology, Seoul National University College of Medicine, Seoul, South Korea (J.H.K.); and Center for Medical-IT Convergence Technology Research, Advanced Institute of Convergence Technology, Suwon, South Korea (J.H.K.)
| | - Kolja M Thierfelder
- From the Department of Diagnostic and Interventional Neuroradiology, RWTH Aachen University, Aachen, Germany (S.A., O.N., M.M., M.W., A.E.O.); Department for Diagnostic and Interventional Radiology, Eberhard Karls University Tuebingen, University Hospital Tuebingen, Hoppe-Seyler-Strasse 3, 72076 Tübingen, Germany (S.A., K.N., A.E.O.); Department of Neuroradiology, University Hospital Mainz, Mainz, Germany (M.A.B., C.B.); Institute for Clinical Radiology, Ludwig-Maximilian-University Hospital Munich, Munich, Germany (K.M.T.); Department of Transdisciplinary Studies, Graduate School of Convergence Science and Technology, Seoul National University, Suwon, South Korea (J.H.K.); Department of Radiology, Seoul National University College of Medicine, Seoul, South Korea (J.H.K.); and Center for Medical-IT Convergence Technology Research, Advanced Institute of Convergence Technology, Suwon, South Korea (J.H.K.)
| | - Marc A Brockmann
- From the Department of Diagnostic and Interventional Neuroradiology, RWTH Aachen University, Aachen, Germany (S.A., O.N., M.M., M.W., A.E.O.); Department for Diagnostic and Interventional Radiology, Eberhard Karls University Tuebingen, University Hospital Tuebingen, Hoppe-Seyler-Strasse 3, 72076 Tübingen, Germany (S.A., K.N., A.E.O.); Department of Neuroradiology, University Hospital Mainz, Mainz, Germany (M.A.B., C.B.); Institute for Clinical Radiology, Ludwig-Maximilian-University Hospital Munich, Munich, Germany (K.M.T.); Department of Transdisciplinary Studies, Graduate School of Convergence Science and Technology, Seoul National University, Suwon, South Korea (J.H.K.); Department of Radiology, Seoul National University College of Medicine, Seoul, South Korea (J.H.K.); and Center for Medical-IT Convergence Technology Research, Advanced Institute of Convergence Technology, Suwon, South Korea (J.H.K.)
| | - Konstantin Nikolaou
- From the Department of Diagnostic and Interventional Neuroradiology, RWTH Aachen University, Aachen, Germany (S.A., O.N., M.M., M.W., A.E.O.); Department for Diagnostic and Interventional Radiology, Eberhard Karls University Tuebingen, University Hospital Tuebingen, Hoppe-Seyler-Strasse 3, 72076 Tübingen, Germany (S.A., K.N., A.E.O.); Department of Neuroradiology, University Hospital Mainz, Mainz, Germany (M.A.B., C.B.); Institute for Clinical Radiology, Ludwig-Maximilian-University Hospital Munich, Munich, Germany (K.M.T.); Department of Transdisciplinary Studies, Graduate School of Convergence Science and Technology, Seoul National University, Suwon, South Korea (J.H.K.); Department of Radiology, Seoul National University College of Medicine, Seoul, South Korea (J.H.K.); and Center for Medical-IT Convergence Technology Research, Advanced Institute of Convergence Technology, Suwon, South Korea (J.H.K.)
| | - Martin Wiesmann
- From the Department of Diagnostic and Interventional Neuroradiology, RWTH Aachen University, Aachen, Germany (S.A., O.N., M.M., M.W., A.E.O.); Department for Diagnostic and Interventional Radiology, Eberhard Karls University Tuebingen, University Hospital Tuebingen, Hoppe-Seyler-Strasse 3, 72076 Tübingen, Germany (S.A., K.N., A.E.O.); Department of Neuroradiology, University Hospital Mainz, Mainz, Germany (M.A.B., C.B.); Institute for Clinical Radiology, Ludwig-Maximilian-University Hospital Munich, Munich, Germany (K.M.T.); Department of Transdisciplinary Studies, Graduate School of Convergence Science and Technology, Seoul National University, Suwon, South Korea (J.H.K.); Department of Radiology, Seoul National University College of Medicine, Seoul, South Korea (J.H.K.); and Center for Medical-IT Convergence Technology Research, Advanced Institute of Convergence Technology, Suwon, South Korea (J.H.K.)
| | - Jong Hyo Kim
- From the Department of Diagnostic and Interventional Neuroradiology, RWTH Aachen University, Aachen, Germany (S.A., O.N., M.M., M.W., A.E.O.); Department for Diagnostic and Interventional Radiology, Eberhard Karls University Tuebingen, University Hospital Tuebingen, Hoppe-Seyler-Strasse 3, 72076 Tübingen, Germany (S.A., K.N., A.E.O.); Department of Neuroradiology, University Hospital Mainz, Mainz, Germany (M.A.B., C.B.); Institute for Clinical Radiology, Ludwig-Maximilian-University Hospital Munich, Munich, Germany (K.M.T.); Department of Transdisciplinary Studies, Graduate School of Convergence Science and Technology, Seoul National University, Suwon, South Korea (J.H.K.); Department of Radiology, Seoul National University College of Medicine, Seoul, South Korea (J.H.K.); and Center for Medical-IT Convergence Technology Research, Advanced Institute of Convergence Technology, Suwon, South Korea (J.H.K.)
| | - Ahmed E Othman
- From the Department of Diagnostic and Interventional Neuroradiology, RWTH Aachen University, Aachen, Germany (S.A., O.N., M.M., M.W., A.E.O.); Department for Diagnostic and Interventional Radiology, Eberhard Karls University Tuebingen, University Hospital Tuebingen, Hoppe-Seyler-Strasse 3, 72076 Tübingen, Germany (S.A., K.N., A.E.O.); Department of Neuroradiology, University Hospital Mainz, Mainz, Germany (M.A.B., C.B.); Institute for Clinical Radiology, Ludwig-Maximilian-University Hospital Munich, Munich, Germany (K.M.T.); Department of Transdisciplinary Studies, Graduate School of Convergence Science and Technology, Seoul National University, Suwon, South Korea (J.H.K.); Department of Radiology, Seoul National University College of Medicine, Seoul, South Korea (J.H.K.); and Center for Medical-IT Convergence Technology Research, Advanced Institute of Convergence Technology, Suwon, South Korea (J.H.K.)
| |
Collapse
|
24
|
Martin T, Hoffman J, Alger JR, McNitt-Gray M, Wang DJ. Low-dose CT perfusion with projection view sharing. Med Phys 2017; 45:101-113. [PMID: 29080274 DOI: 10.1002/mp.12640] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2017] [Revised: 10/13/2017] [Accepted: 10/19/2017] [Indexed: 12/25/2022] Open
Abstract
PURPOSE CT Perfusion (CTP) is a widely used clinical imaging modality. However, CTP typically involves the use of substantial radiation dose (CTDIvol ≥~200 mGy). The purpose of this study is to present a low-dose CTP technique using a projection view-sharing reconstruction algorithm originally developed for dynamic MRI - "K-space Weighted Image Contrast" (KWIC). METHODS The KWIC reconstruction is based on an angle-bisection scheme. In KWIC, a Fourier transform was performed along each projection to form a "k-space"-like CT data space, based on the central-slice theorem. As a projection view-sharing technique, KWIC preserves the spatiotemporal resolution of undersampled CTP data by progressively increasing the number of projection views shared for more distant regions of "k-space". KWIC reconstruction was evaluated on a digital FORBILD head phantom with numerically simulated time-varying objects. The numerically simulated scans were undersampled using the angle-bisection scheme to achieve 50%, 25%, and 12.5% of the original dose (288, 144, and 72 projections, respectively). The area-under-the-curve (AUC), time-to-peak (TTP), and full width half maximum (FWHM) were measured in KWIC recons and compared to fully sampled filtered back projection (FBP) reconstructions. KWIC reconstruction and dose reduction was also implemented for three clinical CTP cases (45 s, 1156 projections per turn, 1 s/turn, CTDIvol 217 mGy). Quantitative perfusion metrics were computed and compared between KWIC reconstructed CTP data and those of standard FBP reconstruction. RESULTS The AUC, TTP, and FWHM in the numerical simzulations were unaffected by the undersampling/dose reduction (down to 12.5% dose) with KWIC reconstruction compared to the fully sampled FBP reconstruction. The normalized root-mean-square-error (NRMSE) of the AUC in the FORBILD head phantom is 0.04, 0.05, and 0.07 for 50%, 25%, and 12.5% KWIC, respectively, as compared to FBP reconstruction. The cerebral blood flow (CBF) and cerebral blood volume had no significant difference between FBP and 50%, 25%, and 12.5% KWIC reconstructions (P > 0.05). CONCLUSIONS This study demonstrates that KWIC preserves perfusion metrics for CTP with substantially reduced dose. Clinical implementation will require further investigation into methods of rapid switching of a CT x-ray source.
Collapse
Affiliation(s)
- Thomas Martin
- Department of Neurology, University of California Los Angeles, Los Angeles, CA, USA
| | - John Hoffman
- Department of Radiological Sciences, University of California Los Angeles, Los Angeles, CA, USA
| | - Jeff R Alger
- Department of Neurology, University of California Los Angeles, Los Angeles, CA, USA
| | - Michael McNitt-Gray
- Department of Radiological Sciences, University of California Los Angeles, Los Angeles, CA, USA
| | - Danny Jj Wang
- Department of Neurology, University of California Los Angeles, Los Angeles, CA, USA.,Laboratory of FMRI Technology (LOFT), Stevens Neuroimaging and Informatics Institute, University of Southern California, Los Angeles, CA, USA
| |
Collapse
|
25
|
Gress DA, Dickinson RL, Erwin WD, Jordan DW, Kobistek RJ, Stevens DM, Supanich MP, Wang J, Fairobent LA. AAPM medical physics practice guideline 6.a.: Performance characteristics of radiation dose index monitoring systems. J Appl Clin Med Phys 2017; 18:12-22. [PMID: 28497529 PMCID: PMC5875816 DOI: 10.1002/acm2.12089] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2016] [Revised: 11/30/2016] [Accepted: 01/20/2017] [Indexed: 11/08/2022] Open
Abstract
The American Association of Physicists in Medicine (AAPM) is a nonprofit professional society whose primary purposes are to advance the science, education and professional practice of medical physics. The AAPM has more than 8,000 members and is the principal organization of medical physicists in the United States. The AAPM will periodically define new practice guidelines for medical physics practice to help advance the science of medical physics and to improve the quality of service to patients throughout the United States. Existing medical physics practice guidelines will be reviewed for the purpose of revision or renewal, as appropriate, on their fifth anniversary or sooner. Each medical physics practice guideline represents a policy statement by the AAPM, has undergone a thorough consensus process in which it has been subjected to extensive review, and requires the approval of the Professional Council. The medical physics practice guidelines recognize that the safe and effective use of diagnostic and therapeutic radiology requires specific training, skills, and techniques, as described in each document. Reproduction or modification of the published practice guidelines and technical standards by those entities not providing these services is not authorized. The following terms are used in the AAPM practice guidelines: •Must and Must Not: Used to indicate that adherence to the recommendation is considered necessary to conform to this practice guideline. •Should and Should Not: Used to indicate a prudent practice to which exceptions may occasionally be made in appropriate circumstances.
Collapse
Affiliation(s)
- Dustin A. Gress
- Department of Imaging PhysicsUniversity of Texas MD Anderson Cancer CenterHoustonTXUSA
| | | | - William D. Erwin
- Department of Imaging PhysicsUniversity of Texas MD Anderson Cancer CenterHoustonTXUSA
| | - David W. Jordan
- Department of RadiologyUniversity Hospitals Cleveland Medical CenterCase Western Reserve UniversityClevelandOHUSA
| | | | - Donna M. Stevens
- Northwest Permanente, PCKaiser Sunnyside Medical CenterClackamasORUSA
| | - Mark P. Supanich
- Department of Diagnostic Radiology and Nuclear MedicineRush University Medical CenterChicagoILUSA
| | - Jia Wang
- Environmental Health and SafetyStanford UniversityStanfordCAUSA
| | | |
Collapse
|
26
|
[Sinogram restoration for low-dose cerebral perfusion CT images]. NAN FANG YI KE DA XUE XUE BAO = JOURNAL OF SOUTHERN MEDICAL UNIVERSITY 2017; 37. [PMID: 28446398 PMCID: PMC6744093 DOI: 10.3969/j.issn.1673-4254.2017.04.08] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
In clinical cerebral perfusion CT examination, repeated scanning the region of interest in the cine mode increases the radiation dose of the patients, while decreasing the radiation dose by lowering the scanning current results in poor image quality and affects the clinical diagnosis. We propose a penalized weighted least-square (PWLS) method for recovering the projection data to improve the quality of low-dose cerebral perfusion CT imaged. This method incorporates the statistical distribution characteristics of brain perfusion CT projection data and uses the statistical properties of the projection data for modeling. The PWLS method was used to recover the data, and the Gauss-Seidel (GS) method was employed for iterative solving. Adaptive weighting is introduced between the original projection data and the projection data after PWLS restoration. The experimental results on the clinical data demonstrated that the PWLS-based sinogram restoration method improved noise reduction and artifact suppression as compared with the conventional noise reduction methods, and better retained the edges and details to generate better cerebral perfusion maps.
Collapse
|
27
|
Ivanidze J, Charalel RA, Shuryak I, Brenner D, Pandya A, Kallas ON, Kesavabhotla K, Segal AZ, Simon MS, Sanelli PC. Effects of Radiation Exposure on the Cost-Effectiveness of CT Angiography and Perfusion Imaging in Aneurysmal Subarachnoid Hemorrhage. AJNR Am J Neuroradiol 2017; 38:462-468. [PMID: 28082263 DOI: 10.3174/ajnr.a5034] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2016] [Accepted: 10/03/2016] [Indexed: 01/01/2023]
Abstract
BACKGROUND AND PURPOSE CT angiography and perfusion imaging is an important prognostic tool in the management of patients with aneurysmal subarachnoid hemorrhage. The purpose of this study was to perform a cost-effectiveness analysis of advanced imaging in patients with SAH, incorporating the risks of radiation exposure from CT angiography and CT perfusion imaging. MATERIALS AND METHODS The risks of radiation-induced brain cancer and cataracts were incorporated into our established decision model comparing the cost-effectiveness of CT angiography and CT perfusion imaging and transcranial Doppler sonography in SAH. Cancer risk was calculated by using National Cancer Institute methodology. The remaining input probabilities were based on literature data and a cohort at our institution. Outcomes were expected quality-adjusted life years gained, costs, and incremental cost-effectiveness ratios. One-way, 2-way, and probabilistic sensitivity analyses were performed. RESULTS CT angiography and CT perfusion imaging were the dominant strategies, resulting in both better health outcomes and lower costs, even when incorporating brain cancer and cataract risks. Our results remained robust in 2-way sensitivity analyses varying the prolonged latency period up to 30 years, with either brain cancer risk up to 50 times higher than the upper 95% CI limit or the probability of cataracts from 0 to 1. Results were consistent for scenarios that considered either symptomatic or asymptomatic patients with SAH. Probabilistic sensitivity analysis confirmed our findings over a broad range of selected input parameters. CONCLUSIONS While risks of radiation exposure represent an important consideration, CT angiography and CT perfusion imaging remained the preferred imaging compared with transcranial Doppler sonography in both asymptomatic and symptomatic patients with SAH, with improved health outcomes and lower health care costs, even when modeling a significantly higher risk and shorter latency period for both cataract and brain cancer than that currently known.
Collapse
Affiliation(s)
- J Ivanidze
- From the Departments of Radiology (J.I., R.A.C., O.N.K., K.K., P.C.S.)
| | - R A Charalel
- From the Departments of Radiology (J.I., R.A.C., O.N.K., K.K., P.C.S.)
| | - I Shuryak
- Department of Radiology (I.S., D.B.), NewYork-Presbyterian Hospital, Columbia University Medical Center, New York, New York
| | - D Brenner
- Department of Radiology (I.S., D.B.), NewYork-Presbyterian Hospital, Columbia University Medical Center, New York, New York
| | - A Pandya
- Department of Health Policy and Management (A.P.), Harvard T.H. Chan School of Public Health, Boston, Massachusetts
| | - O N Kallas
- From the Departments of Radiology (J.I., R.A.C., O.N.K., K.K., P.C.S.)
| | - K Kesavabhotla
- From the Departments of Radiology (J.I., R.A.C., O.N.K., K.K., P.C.S.)
| | | | - M S Simon
- Internal Medicine and Public Health (M.S.S.), Weill Cornell Medical College, NewYork-Presbyterian Hospital, New York, New York
- Department of Radiology (M.S.S., P.C.S.), Northwell Health, Manhasset, New York
| | - P C Sanelli
- From the Departments of Radiology (J.I., R.A.C., O.N.K., K.K., P.C.S.)
- Department of Radiology (M.S.S., P.C.S.), Northwell Health, Manhasset, New York
| |
Collapse
|
28
|
Midgley SM, Stella DL, Campbell BCV, Langenberg F, Einsiedel PF. CT brain perfusion: A static phantom study of contrast-to-noise ratio and radiation dose. J Med Imaging Radiat Oncol 2016; 61:361-366. [DOI: 10.1111/1754-9485.12561] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2016] [Accepted: 10/26/2016] [Indexed: 11/27/2022]
Affiliation(s)
- Stewart M Midgley
- Department of Radiology; Royal Melbourne Hospital and University of Melbourne; Parkville Victoria Australia
- South Australian Medical Imaging; Flinders Medical Centre; Bedford Park South Australia Australia
- School of Physics and Astronomy; Monash University; Clayton Victoria Australia
| | - Damien L Stella
- Department of Radiology; Royal Melbourne Hospital and University of Melbourne; Parkville Victoria Australia
| | - Bruce CV Campbell
- Department of Medicine and Neurology; Royal Melbourne Hospital and University of Melbourne; Parkville Victoria Australia
| | - Francesca Langenberg
- Department of Radiology; Royal Melbourne Hospital and University of Melbourne; Parkville Victoria Australia
| | - Paul F Einsiedel
- Department of Radiology; Royal Melbourne Hospital and University of Melbourne; Parkville Victoria Australia
| |
Collapse
|
29
|
Tian X, Zeng D, Zhang S, Huang J, Zhang H, He J, Lu L, Xi W, Ma J, Bian Z. Robust low-dose dynamic cerebral perfusion CT image restoration via coupled dictionary learning scheme. JOURNAL OF X-RAY SCIENCE AND TECHNOLOGY 2016; 24:837-853. [PMID: 27612048 DOI: 10.3233/xst-160593] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Dynamic cerebral perfusion x-ray computed tomography (PCT) imaging has been advocated to quantitatively and qualitatively assess hemodynamic parameters in the diagnosis of acute stroke or chronic cerebrovascular diseases. However, the associated radiation dose is a significant concern to patients due to its dynamic scan protocol. To address this issue, in this paper we propose an image restoration method by utilizing coupled dictionary learning (CDL) scheme to yield clinically acceptable PCT images with low-dose data acquisition. Specifically, in the present CDL scheme, the 2D background information from the average of the baseline time frames of low-dose unenhanced CT images and the 3D enhancement information from normal-dose sequential cerebral PCT images are exploited to train the dictionary atoms respectively. After getting the two trained dictionaries, we couple them to represent the desired PCT images as spatio-temporal prior in objective function construction. Finally, the low-dose dynamic cerebral PCT images are restored by using a general DL image processing. To get a robust solution, the objective function is solved by using a modified dictionary learning based image restoration algorithm. The experimental results on clinical data show that the present method can yield more accurate kinetic enhanced details and diagnostic hemodynamic parameter maps than the state-of-the-art methods.
Collapse
Affiliation(s)
- Xiumei Tian
- School of Biomedical Engineering, Southern Medical University, Guangzhou, Guangdong, China
- Guangdong Provincial Key Laboratory of Medical Image Processing, Southern Medical University, Guangzhou, Guangdong, China
| | - Dong Zeng
- School of Biomedical Engineering, Southern Medical University, Guangzhou, Guangdong, China
- Guangdong Provincial Key Laboratory of Medical Image Processing, Southern Medical University, Guangzhou, Guangdong, China
| | - Shanli Zhang
- The First Affiliated Hospital of Guangzhou University of Traditional Chinese Medicine, Guangzhou, Guangdong, China
| | - Jing Huang
- School of Biomedical Engineering, Southern Medical University, Guangzhou, Guangdong, China
- Guangdong Provincial Key Laboratory of Medical Image Processing, Southern Medical University, Guangzhou, Guangdong, China
| | - Hua Zhang
- School of Biomedical Engineering, Southern Medical University, Guangzhou, Guangdong, China
- Guangdong Provincial Key Laboratory of Medical Image Processing, Southern Medical University, Guangzhou, Guangdong, China
| | - Ji He
- School of Biomedical Engineering, Southern Medical University, Guangzhou, Guangdong, China
- Guangdong Provincial Key Laboratory of Medical Image Processing, Southern Medical University, Guangzhou, Guangdong, China
| | - Lijun Lu
- School of Biomedical Engineering, Southern Medical University, Guangzhou, Guangdong, China
- Guangdong Provincial Key Laboratory of Medical Image Processing, Southern Medical University, Guangzhou, Guangdong, China
| | - Weiwen Xi
- School of Biomedical Engineering, Southern Medical University, Guangzhou, Guangdong, China
- Guangdong Provincial Key Laboratory of Medical Image Processing, Southern Medical University, Guangzhou, Guangdong, China
| | - Jianhua Ma
- School of Biomedical Engineering, Southern Medical University, Guangzhou, Guangdong, China
- Guangdong Provincial Key Laboratory of Medical Image Processing, Southern Medical University, Guangzhou, Guangdong, China
| | - Zhaoying Bian
- School of Biomedical Engineering, Southern Medical University, Guangzhou, Guangdong, China
- Guangdong Provincial Key Laboratory of Medical Image Processing, Southern Medical University, Guangzhou, Guangdong, China
| |
Collapse
|
30
|
Abstract
Stroke is the leading cause of long-term disability and the second leading cause of mortality in the world, and exerts an enormous burden on the public health. Computed Tomography (CT) remains one of the most widely used imaging modality for acute stroke diagnosis. However when coupled with CT perfusion, the excessive radiation exposure in repetitive imaging to assess treatment response and prognosis has raised significant public concerns regarding its potential hazards to both short- and long-term health outcomes. Tensor total variation has been proposed to reduce the necessary radiation dose in CT perfusion without comprising the image quality by fusing the information of the local anatomical structure with the temporal blood flow model. However the local search in the TTV framework fails to leverage the non-local information in the spatio-temporal data. In this paper, we propose TENDER, an efficient framework of non-local tensor deconvolution to maintain the accuracy of the hemodynamic parameters and the diagnostic reliability in low radiation dose CT perfusion. The tensor total variation is extended using non-local spatio-temporal cubics for regularization, and an efficient algorithm is proposed to reduce the time complexity with speedy similarity computation. Evaluations on clinical data of patients subjects with cerebrovascular disease and normal subjects demonstrate the advantage of non-local tensor deconvolution for reducing radiation dose in CT perfusion.
Collapse
|
31
|
Grimes J, Leng S, Zhang Y, Vrieze T, McCollough C. Implementation and evaluation of a protocol management system for automated review of CT protocols. J Appl Clin Med Phys 2016; 17:523-533. [PMID: 27685112 PMCID: PMC5874106 DOI: 10.1120/jacmp.v17i5.6164] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2015] [Revised: 05/31/2016] [Accepted: 04/25/2016] [Indexed: 12/12/2022] Open
Abstract
Protocol review is important to decrease the risk of patient injury and increase the consistency of CT image quality. A large volume of CT protocols makes manual review labor‐intensive, error‐prone, and costly. To address these challenges, we have developed a software system for automatically managing and monitoring CT protocols on a frequent basis. This article describes our experiences in the implementation and evaluation of this protocol monitoring system. In particular, we discuss various strategies for addressing each of the steps in our protocol‐monitoring workflow, which are: maintaining an accurate set of master protocols, retrieving protocols from the scanners, comparing scanner protocols to master protocols, reviewing flagged differences between the scanner and master protocols, and updating the scanner and/or master protocols. In our initial evaluation focusing only on abdomen and pelvis protocols, we detected 309 modified protocols in a 24‐week trial period. About one‐quarter of these modified protocols were determined to contain inappropriate (i.e., erroneous) protocol parameter modifications that needed to be corrected on the scanner. The most frequently affected parameter was the series description, which was inappropriately modified 47 times. Two inappropriate modifications were made to the tube current, which is particularly important to flag as this parameter impacts both radiation dose and image quality. The CT protocol changes detected in this work provide strong motivation for the use of an automated CT protocol quality control system to ensure protocol accuracy and consistency. PACS number(s): 87.57.Q‐
Collapse
|
32
|
Kalra MK, Sodickson AD, Mayo-Smith WW. CT Radiation: Key Concepts for Gentle and Wise Use. Radiographics 2016; 35:1706-21. [PMID: 26466180 DOI: 10.1148/rg.2015150118] [Citation(s) in RCA: 71] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Use of computed tomography (CT) in medicine comes with the responsibility of its appropriate (wise) and safe (gentle) application to obtain required diagnostic information with the lowest possible dose of radiation. CT provides useful information that may not be available with other imaging modalities in many clinical situations in children and adults. Inappropriate or excessive use of CT should be avoided, especially if required information can be obtained in an accurate and time-efficient manner with other modalities that require a lower radiation dose, or non-radiation-based imaging modalities such as ultrasonography and magnetic resonance imaging. In addition to appropriate use of CT, the radiology community also must monitor scanning practices and protocols. When appropriate, high-contrast regions and lesions should be scanned with reduced dose, but overly zealous dose reduction should be avoided for assessment of low-contrast lesions. Patients' cross-sectional body size should be taken into account to deliver lower radiation dose to smaller patients and children. Wise use of CT scanning with gentle application of radiation dose can help maximize the diagnostic value of CT, as well as address concerns about potential risks of radiation. In this article, key concepts in CT radiation dose are reviewed, including CT dose descriptors; radiation doses from CT procedures; and factors and technologies that affect radiation dose and image quality, including their use in creating dose-saving protocols. Also discussed are the contributions of radiation awareness campaigns such as the Image Gently and Image Wisely campaigns and the American College of Radiology Dose Index Registry initiatives.
Collapse
Affiliation(s)
- Mannudeep K Kalra
- From the Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Boston, Mass (M.K.K.); and Department of Radiology, Brigham and Women's Hospital, 75 Francis St, Boston, MA 02115 and Harvard Medical School, Boston, Mass (A.D.S., W.W.M.S.)
| | - Aaron D Sodickson
- From the Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Boston, Mass (M.K.K.); and Department of Radiology, Brigham and Women's Hospital, 75 Francis St, Boston, MA 02115 and Harvard Medical School, Boston, Mass (A.D.S., W.W.M.S.)
| | - William W Mayo-Smith
- From the Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Boston, Mass (M.K.K.); and Department of Radiology, Brigham and Women's Hospital, 75 Francis St, Boston, MA 02115 and Harvard Medical School, Boston, Mass (A.D.S., W.W.M.S.)
| |
Collapse
|
33
|
Niu S, Zhang S, Huang J, Bian Z, Chen W, Yu G, Liang Z, Ma J. Low-dose cerebral perfusion computed tomography image restoration via low-rank and total variation regularizations. Neurocomputing 2016; 197:143-160. [PMID: 27440948 DOI: 10.1016/j.neucom.2016.01.090] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Cerebral perfusion x-ray computed tomography (PCT) is an important functional imaging modality for evaluating cerebrovascular diseases and has been widely used in clinics over the past decades. However, due to the protocol of PCT imaging with repeated dynamic sequential scans, the associative radiation dose unavoidably increases as compared with that used in conventional CT examinations. Minimizing the radiation exposure in PCT examination is a major task in the CT field. In this paper, considering the rich similarity redundancy information among enhanced sequential PCT images, we propose a low-dose PCT image restoration model by incorporating the low-rank and sparse matrix characteristic of sequential PCT images. Specifically, the sequential PCT images were first stacked into a matrix (i.e., low-rank matrix), and then a non-convex spectral norm/regularization and a spatio-temporal total variation norm/regularization were then built on the low-rank matrix to describe the low rank and sparsity of the sequential PCT images, respectively. Subsequently, an improved split Bregman method was adopted to minimize the associative objective function with a reasonable convergence rate. Both qualitative and quantitative studies were conducted using a digital phantom and clinical cerebral PCT datasets to evaluate the present method. Experimental results show that the presented method can achieve images with several noticeable advantages over the existing methods in terms of noise reduction and universal quality index. More importantly, the present method can produce more accurate kinetic enhanced details and diagnostic hemodynamic parameter maps.
Collapse
Affiliation(s)
- Shanzhou Niu
- School of Mathematics and Computer Sciences, Gannan Normal University, Ganzhou 341000, China ; School of Biomedical Engineering, Southern Medical University, Guangzhou 510515, China
| | - Shanli Zhang
- The First Affiliated Hospital of Guangzhou University of Traditional Chinese Medicine, Guangzhou 510405, China
| | - Jing Huang
- School of Biomedical Engineering, Southern Medical University, Guangzhou 510515, China ; Guangdong Provincial Key Laboratory of Medical Image Processing, Southern Medical University, Guangzhou, Guangdong 510515, China
| | - Zhaoying Bian
- School of Biomedical Engineering, Southern Medical University, Guangzhou 510515, China ; Guangdong Provincial Key Laboratory of Medical Image Processing, Southern Medical University, Guangzhou, Guangdong 510515, China
| | - Wufan Chen
- School of Biomedical Engineering, Southern Medical University, Guangzhou 510515, China ; Guangdong Provincial Key Laboratory of Medical Image Processing, Southern Medical University, Guangzhou, Guangdong 510515, China
| | - Gaohang Yu
- School of Mathematics and Computer Sciences, Gannan Normal University, Ganzhou 341000, China
| | - Zhengrong Liang
- Department of Radiology, State University of New York, Stony Brook, NY 11794, USA
| | - Jianhua Ma
- School of Biomedical Engineering, Southern Medical University, Guangzhou 510515, China ; Guangdong Provincial Key Laboratory of Medical Image Processing, Southern Medical University, Guangzhou, Guangdong 510515, China
| |
Collapse
|
34
|
Cora EA, White PM, Wardlaw JM. Stroke imaging in the age of thrombolysis. IMAGING 2016. [DOI: 10.1259/img.20120004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
|
35
|
Radiation dose reduction in perfusion CT imaging of the brain: A review of the literature. J Neuroradiol 2016; 43:1-5. [DOI: 10.1016/j.neurad.2015.06.003] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2015] [Revised: 06/04/2015] [Accepted: 06/10/2015] [Indexed: 11/30/2022]
|
36
|
Manniesing R, Oei MTH, van Ginneken B, Prokop M. Quantitative Dose Dependency Analysis of Whole-Brain CT Perfusion Imaging. Radiology 2016; 278:190-7. [DOI: 10.1148/radiol.2015142230] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
|
37
|
Othman AE, Afat S, Brockmann C, Nikoubashman O, Bier G, Brockmann MA, Nikolaou K, Tai JH, Yang ZP, Kim JH, Wiesmann M. Low-Dose Volume-Perfusion CT of the Brain: Effects of Radiation Dose Reduction on Performance of Perfusion CT Algorithms. Clin Neuroradiol 2015; 27:311-318. [PMID: 26669592 DOI: 10.1007/s00062-015-0489-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2015] [Accepted: 11/30/2015] [Indexed: 10/22/2022]
Abstract
PURPOSE We aimed to compare different computed tomography (CT) perfusion post-processing algorithms regarding image quality of perfusion maps from low-dose volume perfusion CT (VPCT) and their diagnostic performance regarding the detection of ischemic brain lesions. METHODS AND MATERIALS We included VPCT data of 21 patients with acute stroke (onset < 6h), which were acquired at 80 kV and 180 mAs. Low-dose VPCT datasets with 72 mAs (40 % of original dose) were generated using realistic low-dose simulation. Perfusion maps (cerebral blood volume (CBV); cerebral blood flow (CBF) from original and low-dose datasets were generated using two different commercially available post-processing methods: deconvolution-based method (DC) and maximum slope algorithm (MS). The resulting DC and MS perfusion maps were compared regarding perfusion values, signal-to-noise ratio (SNR) as well as image quality and diagnostic accuracy as rated by two blinded neuroradiologists. RESULTS Quantitative perfusion parameters highly correlated for both algorithms and both dose levels (r ≥ 0.613, p < 0.001). Regarding SNR levels and image quality of the CBV maps, no significant differences between DC and MS were found (p ≥ 0.683). Low-dose MS CBF maps yielded significantly higher SNR levels (p < 0.001) and quality scores (p = 0.014) than those of DC. Low-dose CBF and CBV maps from both DC and MS yielded high sensitivity and specificity for the detection of ischemic lesions (sensitivity ≥ 0.82, specificity ≥ 0.90). CONCLUSION Our results indicate that both methods produce diagnostically sufficient perfusion maps from simulated low-dose VPCT. However, MS produced CBF maps with significantly higher image quality and SNR than DC, indicating that MS might be more suitable for low-dose VPCT imaging.
Collapse
Affiliation(s)
- A E Othman
- Department of Diagnostic and Interventional Neuroradiology, RWTH Aachen University, 52074, Aachen, Germany.,Department for Diagnostic and Interventional Radiology, Eberhard Karls University Tuebingen, University Hospital Tuebingen, 72076, Tübingen, Germany
| | - S Afat
- Department of Diagnostic and Interventional Neuroradiology, RWTH Aachen University, 52074, Aachen, Germany
| | - C Brockmann
- Department of Diagnostic and Interventional Neuroradiology, RWTH Aachen University, 52074, Aachen, Germany
| | - O Nikoubashman
- Department of Diagnostic and Interventional Neuroradiology, RWTH Aachen University, 52074, Aachen, Germany
| | - G Bier
- Department for Diagnostic and Interventional Radiology, Eberhard Karls University Tuebingen, University Hospital Tuebingen, 72076, Tübingen, Germany
| | - M A Brockmann
- Department of Diagnostic and Interventional Neuroradiology, RWTH Aachen University, 52074, Aachen, Germany
| | - K Nikolaou
- Department for Diagnostic and Interventional Radiology, Eberhard Karls University Tuebingen, University Hospital Tuebingen, 72076, Tübingen, Germany
| | - J H Tai
- Center for Medical-IT Convergence Technology Research, Advanced Institute of Convergence Technology, 433-270, Suwon, South Korea
| | - Z P Yang
- Department of Transdisciplinary Studies, Graduate School of Convergence Science and Technology, Seoul National University, 433-270, Suwon, South Korea
| | - J H Kim
- Department of Transdisciplinary Studies, Graduate School of Convergence Science and Technology, Seoul National University, 433-270, Suwon, South Korea. .,Department of Radiology, Seoul National University College of Medicine, 101 Daehak-Ro, Chongno-gu, 110-744, Seoul, South Korea. .,Center for Medical-IT Convergence Technology Research, Advanced Institute of Convergence Technology, 433-270, Suwon, South Korea.
| | - M Wiesmann
- Department of Diagnostic and Interventional Neuroradiology, RWTH Aachen University, 52074, Aachen, Germany
| |
Collapse
|
38
|
Evaluation of diagnostic accuracy in CT perfusion analysis in moyamoya disease. Jpn J Radiol 2015; 34:28-34. [PMID: 26553201 DOI: 10.1007/s11604-015-0497-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2015] [Accepted: 10/20/2015] [Indexed: 10/22/2022]
Abstract
PURPOSE The purpose of the present study was to determine optimal threshold of vascular pixel elimination (VPE) for CT perfusion (CTP) and to assess diagnostic accuracy of CTP by comparing with xenon enhanced CT (XeCT) in moyamoya disease. MATERIALS AND METHODS Twenty-three patients underwent XeCT and CTP. Cerebral blood flow (CBF) images were generated for XeCT and CTP using nine types of software. Region of interest (ROI) measurement was performed on XeCT-CBF and CTP-CBF. Linear regression analysis was performed between XeCT-CBF and CTP-CBF in all software, without and with VPE. The Pearson correlation coefficient was calculated, and an optimal threshold was determined based on maximum correlation coefficients. Correlation coefficients at various VPE thresholds including data of no-VPE were compared with each other. The maximum correlation coefficient at the optimal threshold was also compared. RESULTS Optimal thresholds varied among software types (0.8-2.2 and 7-14 ml/100 g in relative and absolute VPE, respectively). There were significant differences between correlation coefficients at a range of VPE thresholds compared to no-VPE in most software types. There were significant differences in maximum correlation coefficient at optimal threshold among various software types. CONCLUSION Optimal threshold of VPE for CTP could be determined and diagnostic accuracy of CTP varied among software types in moyamoya disease.
Collapse
|
39
|
Vo KD, Yoo AJ, Gupta A, Qiao Y, Vagal AS, Hirsch JA, Yousem DM, Lum C. Multimodal Diagnostic Imaging for Hyperacute Stroke. AJNR Am J Neuroradiol 2015; 36:2206-13. [PMID: 26427831 DOI: 10.3174/ajnr.a4530] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
In April 2015, the American Roentgen Ray Society and the American Society of Neuroradiology cosponsored a unique program designed to evaluate the state of the art in the imaging work-up of acute stroke. This topic has grown in importance because of the recent randomized controlled trials demonstrating the clear efficacy of endovascular stroke treatment. The authors, who were participants in that symposium, will highlight the points of emphasis in this article.
Collapse
Affiliation(s)
- K D Vo
- From the Mallinckrodt Institute of Radiology (K.D.V.), Washington University School of Medicine, St. Louis, Missouri
| | - A J Yoo
- Division of Neurointervention (A.J.Y.), Texas Stroke Institute, Plano, Texas
| | - A Gupta
- Department of Radiology and Feil Family Brain and Mind Research Institute (A.G.), Weill Cornell Medical College, New York, New York
| | - Y Qiao
- Department of Radiology (Y.Q.), Johns Hopkins School of Medicine, Baltimore, Maryland
| | - A S Vagal
- Department of Radiology (A.S.V.), University of Cincinnati Medical Center, Cincinnati, Ohio
| | - J A Hirsch
- NeuroInterventional Radiology (J.A.H.), Massachusetts General Hospital, Boston, Massachusetts
| | - D M Yousem
- Department of Radiology (D.M.Y.), Johns Hopkins Medical Institution, Baltimore, Maryland
| | - C Lum
- Interventional Neuroradiology (C.L.), Ottawa Hospital Research Institute, University of Ottawa, Ottawa, Ontaria, Canada
| |
Collapse
|
40
|
Bricout N, Estrade L, Boustia F, Kalsoum E, Pruvo JP, Leclerc X. Reduced-dose CT protocol for the assessment of cerebral vasospasm. Neuroradiology 2015; 57:1211-8. [PMID: 26315026 DOI: 10.1007/s00234-015-1585-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2015] [Accepted: 08/19/2015] [Indexed: 11/29/2022]
Abstract
INTRODUCTION Despite the increased radiation dose, multimodal CT including noncontrast CT (NCT), CT angiography (CTA), and perfusion CT (PCT) remains a useful tool for the diagnosis of delayed cerebral ischemia (DCI) after aneurysmal subarachnoid hemorrhage (aSAH). The aim of this study was to assess the radiation dose and the image quality between a standard-dose and a reduced-dose multimodal CT protocol. METHODS The study group consisted of 26 aSAH patients with a suspicion of DCI on clinical examination and transcranial doppler. Two different CT protocols were used: a standard-dose protocol (NCT 120 kV, 350 mAs; CTA 100 kV, 250 mAs; PCT 80 kV, 200 mAs) from August 2011 to October 2013 (n = 13) and a reduced-dose protocol (NCT 100 kV, 400 mAs; CTA 100 kV, 220 mAs; PCT 80 kV, 180 mAs) from November 2013 to May 2014 (n = 13). Dose-length product (DLP), effective dose, volume CT dose index (CTDI), signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and overall image quality were determined for each examination. RESULTS The overall image quality was judged as good or excellent in all cases. The reduced-dose protocol allowed a 15 % decrease in both the median total DLP (2438 vs 2898 mGy cm, p < 0.0001) and the effective dose as well as a significant decrease in median CTDI of 23, 31, and 10 % for NCT, CTA, and CTP, respectively. This dose reduction did not result in significant alteration of SNR (except for NCT) or CNR between groups. CONCLUSION The present study showed that the reduced-dose multimodal CT protocol enabled a significant reduction of radiation dose without image quality impairment.
Collapse
Affiliation(s)
- N Bricout
- Department of Neuroradiology, Université Lille Nord de France, Hôpital Roger Salengro, CHRU de Lille, Avenue Emile-Laine, 59037, Lille cedex, France.
| | - L Estrade
- Department of Neuroradiology, Université Lille Nord de France, Hôpital Roger Salengro, CHRU de Lille, Avenue Emile-Laine, 59037, Lille cedex, France
| | - F Boustia
- Department of Neuroradiology, Université Lille Nord de France, Hôpital Roger Salengro, CHRU de Lille, Avenue Emile-Laine, 59037, Lille cedex, France
| | - E Kalsoum
- Department of Neuroradiology, Université Lille Nord de France, Hôpital Roger Salengro, CHRU de Lille, Avenue Emile-Laine, 59037, Lille cedex, France
| | - J P Pruvo
- Department of Neuroradiology, Université Lille Nord de France, Hôpital Roger Salengro, CHRU de Lille, Avenue Emile-Laine, 59037, Lille cedex, France
| | - X Leclerc
- Department of Neuroradiology, Université Lille Nord de France, Hôpital Roger Salengro, CHRU de Lille, Avenue Emile-Laine, 59037, Lille cedex, France
| |
Collapse
|
41
|
Rehani MM, Gupta R, Bartling S, Sharp GC, Pauwels R, Berris T, Boone JM. Radiological Protection in Cone Beam Computed Tomography (CBCT). ICRP Publication 129. Ann ICRP 2015; 44:9-127. [PMID: 26116562 DOI: 10.1177/0146645315575485] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The objective of this publication is to provide guidance on radiological protection in the new technology of cone beam computed tomography (CBCT). Publications 87 and 102 dealt with patient dose management in computed tomography (CT) and multi-detector CT. The new applications of CBCT and the associated radiological protection issues are substantially different from those of conventional CT. The perception that CBCT involves lower doses was only true in initial applications. CBCT is now used widely by specialists who have little or no training in radiological protection. This publication provides recommendations on radiation dose management directed at different stakeholders, and covers principles of radiological protection, training, and quality assurance aspects. Advice on appropriate use of CBCT needs to be made widely available. Advice on optimisation of protection when using CBCT equipment needs to be strengthened, particularly with respect to the use of newer features of the equipment. Manufacturers should standardise radiation dose displays on CBCT equipment to assist users in optimisation of protection and comparisons of performance. Additional challenges to radiological protection are introduced when CBCT-capable equipment is used for both fluoroscopy and tomography during the same procedure. Standardised methods need to be established for tracking and reporting of patient radiation doses from these procedures. The recommendations provided in this publication may evolve in the future as CBCT equipment and applications evolve. As with previous ICRP publications, the Commission hopes that imaging professionals, medical physicists, and manufacturers will use the guidelines and recommendations provided in this publication for implementation of the Commission's principle of optimisation of protection of patients and medical workers, with the objective of keeping exposures as low as reasonably achievable, taking into account economic and societal factors, and consistent with achieving the necessary medical outcomes.
Collapse
|
42
|
Sanelli PC. Robust Low-Dose CT Perfusion Deconvolution via Tensor Total-Variation Regularization. IEEE TRANSACTIONS ON MEDICAL IMAGING 2015; 34:1533-1548. [PMID: 25706579 PMCID: PMC4779066 DOI: 10.1109/tmi.2015.2405015] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Acute brain diseases such as acute strokes and transit ischemic attacks are the leading causes of mortality and morbidity worldwide, responsible for 9% of total death every year. "Time is brain" is a widely accepted concept in acute cerebrovascular disease treatment. Efficient and accurate computational framework for hemodynamic parameters estimation can save critical time for thrombolytic therapy. Meanwhile the high level of accumulated radiation dosage due to continuous image acquisition in CT perfusion (CTP) raised concerns on patient safety and public health. However, low-radiation leads to increased noise and artifacts which require more sophisticated and time-consuming algorithms for robust estimation. In this paper, we focus on developing a robust and efficient framework to accurately estimate the perfusion parameters at low radiation dosage. Specifically, we present a tensor total-variation (TTV) technique which fuses the spatial correlation of the vascular structure and the temporal continuation of the blood signal flow. An efficient algorithm is proposed to find the solution with fast convergence and reduced computational complexity. Extensive evaluations are carried out in terms of sensitivity to noise levels, estimation accuracy, contrast preservation, and performed on digital perfusion phantom estimation, as well as in vivo clinical subjects. Our framework reduces the necessary radiation dose to only 8% of the original level and outperforms the state-of-art algorithms with peak signal-to-noise ratio improved by 32%. It reduces the oscillation in the residue functions, corrects over-estimation of cerebral blood flow (CBF) and under-estimation of mean transit time (MTT), and maintains the distinction between the deficit and normal regions.
Collapse
|
43
|
Lin CJ, Mok GSP, Tsai MF, Tsai WT, Yang BH, Tu CY, Wu TH. National Survey of Radiation Dose and Image Quality in Adult CT Head Scans in Taiwan. PLoS One 2015; 10:e0131243. [PMID: 26125549 PMCID: PMC4488422 DOI: 10.1371/journal.pone.0131243] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2014] [Accepted: 05/30/2015] [Indexed: 11/18/2022] Open
Abstract
Introduction The purpose of the present study was to evaluate the influence of different variables on radiation dose and image quality based on a national database. Materials and Methods Taiwan’s Ministry of Health and Welfare requested all radiology departments to complete a questionnaire for each of their CT scanners. Information gathered included all scanning parameters for CT head scans. For the present analysis, CT machines were divided into three subgroups: single slice CT (Group A); multi-detector CT (MDCT) with 2-64 slices (Group B); and MDCT with more than 64 slices (Group C). Correlations between computed tomography dose index (CTDI) and signal-to-noise ratio (SNR) with cumulated tube rotation number (CTW(n)) and cumulated tube rotation time (CTW(s)), and sub group analyses of CTDI and SNR across the three groups were performed. Results CTDI values demonstrated a weak correlation (r = 0.33) with CTW(n) in Group A. SNR values demonstrated a weak negative correlation (r = -0.46) with CTW(n) in Group C. MDCT with higher slice numbers used more tube potential resulting in higher effective doses. There were both significantly lower CTDI and SNR values in helical mode than in axial mode in Group B, but not Group C. Conclusion CTW(n) and CTW(s) did not influence radiation output. Helical mode is more often used in MDCT and results in both lower CTDI and SNR compared to axial mode in MDCT with less than 64 slices.
Collapse
Affiliation(s)
- Chung-Jung Lin
- School of Medicine, National Yang-Ming University, Taipei, Taiwan
- Department of Radiology, Taipei Veterans General Hospital, Taipei, Taiwan
| | - Greta S. P. Mok
- Biomedical Imaging Laboratory, Department of Electrical and Computer Engineering, Faculty of Science and Technology, University of Macau, Macau, China
| | - Mang-Fen Tsai
- Department of Biomedical Imaging and Radiological Sciences, National Yang Ming University, Taipei, Taiwan
| | - Wei-Ta Tsai
- Department of Biomedical Imaging and Radiological Sciences, National Yang Ming University, Taipei, Taiwan
- Department of Radiation Oncology, Tzu Chi General Hospital Dalin Branch, Chiayi, Taiwan
- Association of Medical Radiation Technologists, Taipei, Taiwan
| | - Bang-Hung Yang
- Department of Biomedical Imaging and Radiological Sciences, National Yang Ming University, Taipei, Taiwan
- Department of Nuclear Medicine, Taipei Veterans General Hospital, Taipei, Taiwan
- Association of Medical Radiation Technologists, Taipei, Taiwan
| | - Chun-Yuan Tu
- Department of Biomedical Imaging and Radiological Sciences, National Yang Ming University, Taipei, Taiwan
- Department of Radiology, Mackay Memorial Hospital, Taipei, Taiwan
- Association of Medical Radiation Technologists, Taipei, Taiwan
- * E-mail: (THW); (CYT)
| | - Tung-Hsin Wu
- Department of Biomedical Imaging and Radiological Sciences, National Yang Ming University, Taipei, Taiwan
- * E-mail: (THW); (CYT)
| |
Collapse
|
44
|
Goenka AH, Dong F, Wildman B, Hulme K, Johnson P, Herts BR. CT Radiation Dose Optimization and Tracking Program at a Large Quaternary-Care Health Care System. J Am Coll Radiol 2015; 12:703-10. [DOI: 10.1016/j.jacr.2015.03.037] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2015] [Accepted: 03/23/2015] [Indexed: 10/23/2022]
|
45
|
Impact of image denoising on image quality, quantitative parameters and sensitivity of ultra-low-dose volume perfusion CT imaging. Eur Radiol 2015; 26:167-74. [DOI: 10.1007/s00330-015-3853-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2015] [Revised: 04/20/2015] [Accepted: 05/13/2015] [Indexed: 10/23/2022]
|
46
|
Othman AE, Brockmann C, Yang Z, Kim C, Afat S, Pjontek R, Nikoubashman O, Brockmann MA, Kim JH, Wiesmann M. Effects of radiation dose reduction in Volume Perfusion CT imaging of acute ischemic stroke. Eur Radiol 2015; 25:3415-22. [PMID: 25903716 DOI: 10.1007/s00330-015-3763-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2015] [Revised: 03/11/2015] [Accepted: 04/01/2015] [Indexed: 11/25/2022]
Abstract
PURPOSE To examine the influence of radiation dose reduction on image quality and sensitivity of Volume Perfusion CT (VPCT) maps regarding the detection of ischemic brain lesions. METHODS AND MATERIALS VPCT data of 20 patients with suspected ischemic stroke acquired at 80 kV and 180 mAs were included. Using realistic reduced-dose simulation, low-dose VPCT datasets with 144 mAs, 108 mAs, 72 mAs and 36 mAs (80 %, 60 %, 40 % and 20 % of the original levels) were generated, resulting in a total of 100 datasets. Perfusion maps were created and signal-to-noise-ratio (SNR) measurements were performed. Qualitative analyses were conducted by two blinded readers, who also assessed the presence/absence of ischemic lesions and scored CBV and CBF maps using a modified ASPECTS-score. RESULTS SNR of all low-dose datasets were significantly lower than those of the original datasets (p < .05). All datasets down to 72 mAs (40 %) yielded sufficient image quality and high sensitivity with excellent inter-observer-agreements, whereas 36 mAs datasets (20 %) yielded poor image quality in 15 % of the cases with lower sensitivity and inter-observer-agreements. CONCLUSION Low-dose VPCT using decreased tube currents down to 72 mAs (40 % of original radiation dose) produces sufficient perfusion maps for the detection of ischemic brain lesions. KEY POINTS • Perfusion CT is highly accurate for the detection of ischemic brain lesions • Perfusion CT results in high radiation exposure, therefore low-dose protocols are required • Reduction of tube current down to 72 mAs produces sufficient perfusion maps.
Collapse
Affiliation(s)
- Ahmed E Othman
- Department of Diagnostic and Interventional Neuroradiology, RWTH Aachen University, 52074, Aachen, Germany.
- Department for Diagnostic and Interventional Radiology, Eberhard Karls University Tuebingen, University Hospital Tuebingen, Hoppe-Seyler-Straße 3, 72076, Tübingen, Germany.
| | - Carolin Brockmann
- Department of Diagnostic and Interventional Neuroradiology, RWTH Aachen University, 52074, Aachen, Germany
| | - Zepa Yang
- Department of Transdisciplinary Studies, Graduate School of Convergence Science and Technology, Seoul National University, Suwon, 433-270, South Korea
- Department of Radiology, Seoul National University College of Medicine, Seoul, 110-744, South Korea
| | - Changwon Kim
- Department of Transdisciplinary Studies, Graduate School of Convergence Science and Technology, Seoul National University, Suwon, 433-270, South Korea
- Department of Radiology, Seoul National University College of Medicine, Seoul, 110-744, South Korea
| | - Saif Afat
- Department of Diagnostic and Interventional Neuroradiology, RWTH Aachen University, 52074, Aachen, Germany
| | - Rastislav Pjontek
- Department of Diagnostic and Interventional Neuroradiology, RWTH Aachen University, 52074, Aachen, Germany
| | - Omid Nikoubashman
- Department of Diagnostic and Interventional Neuroradiology, RWTH Aachen University, 52074, Aachen, Germany
| | - Marc A Brockmann
- Department of Diagnostic and Interventional Neuroradiology, RWTH Aachen University, 52074, Aachen, Germany
| | - Jong Hyo Kim
- Department of Transdisciplinary Studies, Graduate School of Convergence Science and Technology, Seoul National University, Suwon, 433-270, South Korea
- Department of Radiology, Seoul National University College of Medicine, Seoul, 110-744, South Korea
- Center for Medical-IT Convergence Technology Research, Advanced Institute of Convergence Technology, Suwon, 433-270, South Korea
| | - Martin Wiesmann
- Department of Diagnostic and Interventional Neuroradiology, RWTH Aachen University, 52074, Aachen, Germany
| |
Collapse
|
47
|
Bjarnason TA, Thakur Y, Chakraborty S, Liu P, O'Malley ME, Coulden R, Noga M, Mason A, Mayo J. Canadian Association of Radiologists Radiation Protection Working Group: Automated Patient-Specific Dose Registries—What Are They and What Are They Good for? Can Assoc Radiol J 2015; 66:192-7. [PMID: 25896452 DOI: 10.1016/j.carj.2014.12.005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2014] [Revised: 11/28/2014] [Accepted: 12/01/2014] [Indexed: 10/23/2022] Open
Abstract
Medical radiation should be used appropriately and with a dose as low as reasonably achievable. Dose monitoring technologies have been developed that automatically accumulate patient dose indicators, providing effective dose estimates and patient-specific dose histories. Deleterious radiation related events have prompted increased public interest in the safe use of medical radiation. Some view individualized patient dose histories as a tool to help manage the patient dose. However, it is imperative that dose monitoring technologies be evaluated on the outcomes of dose reduction and effective patient management. Patient dose management needs to be consistent with the widely accepted linear no-threshold model of stochastic radiation effects. This essay reviews the attributes and limitations of dose monitoring technologies to provoke discussion regarding resource allocation in the current fiscally constrained health care system.
Collapse
Affiliation(s)
- Thorarin A Bjarnason
- Diagnostic Imaging Services, Interior Health, Kelowna, British Columbia, Canada; Department of Radiology, University of British Columbia, Vancouver, British Columbia, Canada; Department of Mathematics, Statistics, Physics & Computer Science, University of British Columbia Okanagan, Kelowna, British Columbia, Canada.
| | - Yogesh Thakur
- Department of Radiology, University of British Columbia, Vancouver, British Columbia, Canada; Integrated Medical Imaging, Vancouver Coastal Health Authority, Vancouver, British Columbia, Canada
| | - Santanu Chakraborty
- Department of Radiology, University of Ottawa, Ottawa, Ontario, Canada; Department of Diagnostic Imaging, The Ottawa Hospital, Ottawa, Ontario, Canada
| | - Peter Liu
- KMH HealthCare Centres, Mississauga, Ontario, Canada
| | - Martin E O'Malley
- Joint Department of Medical Imaging, University of Toronto, Toronto, Ontario, Canada; Princess Margaret Hospital, Toronto, Ontario, Canada
| | - Richard Coulden
- Department of Radiology and Diagnostic Imaging, University of Alberta, Edmonton, Alberta, Canada
| | - Michelle Noga
- Department of Radiology and Diagnostic Imaging, University of Alberta, Edmonton, Alberta, Canada
| | - Andrew Mason
- Medical Imaging Department, Ridge Meadows Hospital, Maple Ridge, British Columbia, Canada
| | - John Mayo
- Department of Radiology, University of British Columbia, Vancouver, British Columbia, Canada; Integrated Medical Imaging, Vancouver Coastal Health Authority, Vancouver, British Columbia, Canada
| |
Collapse
|
48
|
Early CT perfusion changes and blood-brain barrier permeability after aneurysmal subarachnoid hemorrhage. Neuroradiology 2015; 57:767-73. [PMID: 25868518 DOI: 10.1007/s00234-015-1529-1] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2015] [Accepted: 04/01/2015] [Indexed: 12/30/2022]
Abstract
INTRODUCTION Early brain injury (EBI) can occur within 72 h of aneurysmal subarachnoid hemorrhage (aSAH). The objective of this study was to determine if there are differences in early CTP parameters (<72 h) with respect to delayed cerebral ischemia (DCI), cerebral infarction, and functional outcome. METHODS We performed a prospective cohort study of aSAH patients admitted to a single tertiary care center. MTT, CBF and blood-brain barrier permeability (PS) were quantified with CTP within 72 h of aneurysm rupture. Primary outcomes were functional outcome by the Modified Rankin Scale (mRS) at 3 months and cerebral infarction. Secondary outcome was the development of DCI. Differences between early CTP parameters were determined with respect to primary and secondary outcomes. RESULTS Fifty aSAH patients were included in the final analysis. MTT was significantly higher in patients who developed DCI (6.7 ± 1.2 vs 5.9 ± 1.0; p = 0.03) and cerebral infarction (7.0 ± 1.2 vs 5.9 ± 0.9; p = 0.007); however, no difference in MTT was found between patients with and without a poor outcome (mRS > 2). Early CBF and PS did not differ with respect to functional outcome, DCI, and cerebral infarction. CONCLUSIONS Elevated MTT within 72 h of aneurysm rupture is associated with DCI and cerebral infarction but not with long-term functional outcome. Blood-brain barrier permeability, as assessed by CT perfusion, was not associated with DCI or worse outcome in this cohort.
Collapse
|
49
|
Tensor total-variation regularized deconvolution kegularlzea ueconvolution for efficient low-dose CT perfusion. ACTA ACUST UNITED AC 2014; 17:154-61. [PMID: 25333113 DOI: 10.1007/978-3-319-10404-1_20] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
Acute brain diseases such as acute stroke and transit ischemic attacks are the leading causes of mortality and morbidity worldwide, responsible for 9% of total death every year. 'Time is brain' is a widely accepted concept in acute cerebrovascular disease treatment. Efficient and accurate computational framework for hemodynamic parameters estimation can save critical time for thrombolytic therapy. Meanwhile the high level of accumulated radiation dosage due to continuous image acquisition in CT perfusion (CTP) raised concerns on patient safety and public health. However, low-radiation will lead to increased noise and artifacts which require more sophisticated and time-consuming algorithms for robust estimation. We propose a novel efficient framework using tensor total-variation (TTV) regularization to achieve both high efficiency and accuracy in deconvolution for low-dose CTP. The method reduces the necessary radiation dose to only 8% of the original level and outperforms the state-of-art algorithms with estimation error reduced by 40%. It also corrects over-estimation of cerebral blood flow (CBF) and under-estimation of mean transit time (MTT), at both normal and reduced sampling rate. An efficient computational algorithm is proposed to find the solution with fast convergence.
Collapse
|
50
|
Low dose CT perfusion in acute ischemic stroke. Neuroradiology 2014; 56:1055-62. [PMID: 25252738 DOI: 10.1007/s00234-014-1434-z] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2014] [Accepted: 09/16/2014] [Indexed: 02/04/2023]
Abstract
INTRODUCTION The purpose of this investigation is to determine if CT perfusion (CTP) measurements at low doses (LD = 20 or 50 mAs) are similar to those obtained at regular doses (RD = 100 mAs), with and without the addition of adaptive statistical iterative reconstruction (ASIR). METHODS A single-center, prospective study was performed in patients with acute ischemic stroke (n = 37; 54% male; age = 74 ± 15 years). Two CTP scans were performed on each subject: one at 100 mAs (RD) and one at either 50 or 20 mAs (LD). CTP parameters were compared between the RD and LD scans in regions of ischemia, infarction, and normal tissue. Differences were determined using a within-subjects ANOVA (p < 0.05) followed by a paired t test post hoc analysis (p < 0.01). RESULTS At 50 mAs, there was no significant difference between cerebral blood flow (CBF), cerebral blood volume (CBV), or time to maximum enhancement (Tmax) values for the RD and LD scans in the ischemic, infarcted, or normal contralateral regions (p < 0.05). At 20 mAs, there were significant differences between the RD and LD scans for all parameters in the ischemic and normal tissue regions (p > 0.05). CONCLUSION CTP-derived CBF and CBV are not different at 50 mAs compared to 100 mAs, even without the addition of ASIR. Current CTP protocols can be modified to reduce the effective dose by 50 % without altering CTP measurements.
Collapse
|