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      Visualization of flow dynamics in the portal circulation using 320-detector-row computed tomography: a feasibility study

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          Abstract

          Multidetector row computed tomography (CT) scanners perform dynamic scanning and have a wide scan range. Time-resolved three-dimensional CT ( i.e., 4D CT) has recently enabled visualization of flow in neurovascular vessels. We hypothesized that 4D CT technology would be a useful and non-invasive method for visualizing the flow dynamics of the portal circulation. The aim of this study was to evaluate the technical feasibility of 4D CT for visualizing flow dynamics in the portal circulation using 320-detector-row CT. 4D CT images of 18 consecutive patients with portal circulation including gastrorenal shunt were retrospectively evaluated for their ability to generate flow dynamics of the portal circulation. Flow dynamics could be visualized by 4D CT in 68 of the 72 vessels in the portal vein, splenic vein, superior mesenteric vein, and gastrorenal shunt. Flow direction could not be identified in four vessels, all of them being superior mesenteric veins. Flow direction was recognized on 4D CT in the 68 vessels of the portal circulation. A preliminary validation study revealed that flow direction of all 19 vessels in the portal circulation had concordance between 4D CT and color Doppler ultrasound. 4D CT could visualize flow dynamics of the portal circulation.

          Supplementary Information

          The online version contains supplementary material available at 10.1186/s41747-020-00197-8.

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          U.S. Diagnostic Reference Levels and Achievable Doses for 10 Adult CT Examinations.

          Purpose To develop diagnostic reference levels (DRLs) and achievable doses (ADs) for the 10 most common adult computed tomographic (CT) examinations in the United States as a function of patient size by using the CT Dose Index Registry. Materials and Methods Data from the 10 most commonly performed adult CT head, neck, and body examinations from 583 facilities were analyzed. For head examinations, the lateral thickness was used as an indicator of patient size; for neck and body examinations, water-equivalent diameter was used. Data from 1 310 727 examinations (analyzed by using SAS 9.3) provided median values, as well as means and 25th and 75th (DRL) percentiles for volume CT dose index (CTDIvol), dose-length product (DLP), and size-specific dose estimate (SSDE). Applicable results were compared with DRLs from eight countries. Results More than 46% of the facilities were community hospitals; 13% were academic facilities. More than 48% were in metropolitan areas, 39% were suburban, and 13% were rural. More than 50% of the facilities performed fewer than 500 examinations per month. The abdomen and pelvis was the most frequently performed examination in the study (45%). For body examinations, DRLs (75th percentile) and ADs (median) for CTDIvol, SSDE, and DLP increased consistently with the patient's size (water-equivalent diameter). The relationships between patient size and DRLs and ADs were not as strong for head and neck examinations. These results agree well with the data from other countries. Conclusion DRLs and ADs as a function of patient size were developed for the 10 most common adult CT examinations performed in the United States. © RSNA, 2017.
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            Noninvasive assessment of portal hypertension in patients with cirrhosis.

            Severe portal hypertension is responsible for complications and death. Although measurement of the hepatic venous pressure gradient is the most accurate method for evaluating the presence and severity of portal hypertension, this technique is considered invasive and is not routinely performed in all centers. Several noninvasive techniques have been proposed to measure portal hypertension. Certain methods evaluate elements related to the pathogenesis of portal hypertension through the measurement of hyperkinetic syndrome, for example, or they investigate the development of hepatic fibrosis through the measurement of increased intrahepatic vascular resistance. Other methods evaluate the clinical consequences of portal hypertension, such as the presence of esophageal varices or the development of portosystemic shunts. Methods evaluating increased hepatic vascular resistance are fairly accurate and mainly involve the detection of hepatic fibrosis by serum markers and transient elastography. The radiological assessment of hyperkinetic syndrome probably has value but is still under investigation. The assessment of severe portal hypertension by the presence of varices may be performed with simple tools such as biological assays, computed tomography, and esophageal capsules. More sophisticated procedures seem promising but are still under development. Screening tools for large populations must be simple, whereas more complicated procedures could help in the follow-up of already diagnosed patients. Although most of these noninvasive methods effectively identify severe portal hypertension, methods for diagnosing moderate portal hypertension need to be developed; this shows that further investigation is needed in this field. Copyright © 2010 American Association for the Study of Liver Diseases.
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              Haemodynamic evaluation by Doppler ultrasonography in patients with portal hypertension: a review.

              Soon Baik (2010)
              Doppler ultrasonography (US) has an advantage of being non-invasive; therefore, several attempts have been made to investigate the haemodynamic alterations in cirrhosis and the response to medical treatment of portal hypertension. Doppler indices, which have been commonly used for the evaluation of portal hypertension, include the measurement of portal and splenic venous blood velocity and flows, and the resistive and pulsatility index at hepatic, splenic, renal, superior mesenteric artery. Although many positive evidences have been suggested, its clinical usefulness in portal hypertension remains unsettled because of being plagued by lack of reproducibility and accuracy characterized by intra- and interobserver variation. However, recently, Doppler's usefulness in assessment of severity of portal hypertension in terms of reproducibility, technical ease and accuracy and response to drugs that reduce the portal pressure has been proposed. In addition, because most of the patients with cirrhosis and portal hypertension have intrahepatic shunts, they show a decrease in intrahepatic circulatory time (IHCT). Doppler US using microbubble contrast agents allows measurement of IHCT. Therefore, application of contrast-enhanced Doppler US can be prospective for the assessment of the severity of portal hypertension. Several reports have demonstrated that colour Doppler endoscopic US enable haemodynamic study to assess the portal hypertension and has a role of guidance to measure the imaging-based variceal pressure. We have reviewed briefly the clinical usefulness of Doppler US in assessing the severity of portal hypertension and its response to treatment.
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                Author and article information

                Contributors
                kageyama@med.osaka-cu.ac.jp
                Journal
                Eur Radiol Exp
                Eur Radiol Exp
                European Radiology Experimental
                Springer International Publishing (Cham )
                2509-9280
                12 January 2021
                12 January 2021
                December 2021
                : 5
                : 1
                Affiliations
                [1 ]GRID grid.261445.0, ISNI 0000 0001 1009 6411, Department of Diagnostic and Interventional Radiology, Graduate School of Medicine, , Osaka City University, ; 1-4-3 Asahi-machi, Abeno-ku, Osaka, 545-8585 Japan
                [2 ]GRID grid.470114.7, Department of Central Radiology, , Osaka City University Hospital, ; 1-5-7 Asahi-machi, Abeno-ku, Osaka, 545-8586 Japan
                Author information
                http://orcid.org/0000-0002-0787-9789
                Article
                197
                10.1186/s41747-020-00197-8
                7801554
                33432529
                7d3e2fa8-5397-4a57-8f7e-12132f7721c9
                © The Author(s) 2021

                Open AccessThis article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.

                History
                : 30 August 2020
                : 26 November 2020
                Categories
                Technical Note
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                © The Author(s) 2021

                four-dimensional computed tomography,hypertension (portal),multidetector computed tomography,portal vein,portasystemic shunt

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