what is patent hepatic vasculature

Axial CTA at the level of the carina (a) shows no opacification of pulmonary artery, ventricles, or aorta. PubMed What Is A Patent Portal Vein And What Is Patent Hepatic Artery And A Patent Hepatic Vein ? The portal vein and hepatic artery provide blood flow to the liver. The hepatic veins (there are three) carry blood out of the liver and empty into the vena cava. When they are "patent" it means that they are open and flowing normally. Contrast extravasation rates during CT imaging range between 0.1 and 0.9%, with an average rate of 0.4% [13, 14]. ACR Manual on Contrast Media discusses the treatment of contrast extravasation [9]. Quantitative radiology: automated CT liver volumetry compared with interactive volumetry and manual volumetry. Test. Should the objective be to flow from the gastrointestinal tract to the inferior vena cava and the heart, then the straight channel would be the configuration that we should see. The lobule is considered to be the liver functional unit, the elemental system. Google Scholar, Lakoma A, Tuite D, Sheehan J, Weale P, Carr JC (2010) Measurement of pulmonary circulation parameters using time-resolved MR angiography in patients after Ross procedure. PANCREAS: Normal morphology and enhancement. Unable to process the form. The https:// ensures that you are connecting to the A delayed phase, 40s acquisition can help in identifying any thrombus, vegetation, or fibrin sheath attached to the catheter. Enter search terms to find related medical topics, multimedia and more. In this case we see an altered pattern of contrast flow: first SVC, followed by minimal opacification of the pulmonary artery and ascending aorta, dense opacification of the descending aorta followed by dense opacification of the ascending aorta. The CT technician subsequently called the radiologist to check the images and ask for a repeat injection after identifying abnormal contrast enhancement. The organisms infect the read more , primary biliary cholangitis Primary Biliary Cholangitis (PBC) Primary biliary cholangitis (PBC; formerly known as primary biliary cirrhosis) is an autoimmune liver disorder characterized by the progressive destruction of intrahepatic bile ducts, leading read more (PBC, previously called primary biliary cirrhosis), sarcoidosis Sarcoidosis Sarcoidosis is an inflammatory disorder resulting in noncaseating granulomas in one or more organs and tissues; etiology is unknown. Debbaut C, et al. The most obvious unique features include the dual vascular supply; the mechanism of intrinsic regulation of the hepatic artery (the hepatic arterial buffer response); the fact that portal blood flow, supplying two thirds of liver blood flow, is not controlled directly by the liver; the fact that 20% of the cardiac When present, these findings should raise the suspicion of altered flow dynamics including underlying intra- or extra-cardiac shunt. Hepatic artery. The entire volume of the lobules is fixed because the blood volume is fixed. 648, Rochester, NY, 14642, USA, Abhishek Chaturvedi,Daniel Oppenheimer,Katherine A. Kaproth-Joslin&Apeksha Chaturvedi, Department of Radiology, University of Texas Southwestern, Dallas, TX, USA, You can also search for this author in In test bolus technique, a small amount of contrast is injected followed by saline chaser at the predetermined flow rate to identify contrast arrival in target vessels. The blood flow path is represented by the arrows. Received 2019 Dec 23; Accepted 2020 Sep 10. Flashcards. Normal hepatic anatomy occurs in approximately 80% of cases, for the remaining 20% multiple variations have been described. LIVER AND BILIARY: Normal liver morphology and enhancement. PubMed From a rheological viewpoint, blood belongs to the class of shear shinning fluids, also called pseudo-plastic, as its dynamic viscosity decreases when the shear strain increases. Contrast opacifies the right portal vein secondary to backflow from hepatic vein into portal vein. Each tree architecture is composed of a main trunk subdivided into smaller and smaller braches. Siggers JH, Leungchavaphongse K, Ho CH, Repetto R. Mathematical model of blood and interstitial flow and lymph production in the liver. Torres Rojas AM, Meza Romero A, Pagonabarraga I, Travasso RDM, Corvera Poir E. Obstructions in vascular networks: relation between network morphology and blood supply. An optimal, diagnostic thoracic CTA study is never obtained by accident. No ascites. Axial CTA images being obtained in a patient suspected for acute aortic syndrome and found to be in asystole with no cardiac output. The flow path is represented on the left hand side of Fig. Debbaut C, et al. Therefore, from the measurements of 4 representative portions of the liver, they considered that the total number of branches could be estimated in proportion of the total liver volume. Clin Radiol 69(12):12641272, Article CAS Debbaut C, et al. In accord with the constructal law of design32, fluid architectures evolve in time to facilitate access to the currents flowing through them, for minimum pumping power. Bejan A. Box no. In the simplest case we assume that the ducts have a round cross section of diameter d and length L. The pulsatile nature of blood flow in the hepatic artery network is classically expressed through an electrical impedance analogy. We demonstrated previously that beyond the value of 6 connected branches, radial networks should be replaced by tree-shaped ones with optimized diameter ratios (Eq. Extravasation of contrast material, in which contrast medium is injected outside the intended vessel, is an infrequent, but well known complicationof CTA (Fig. Virtual liver networks combine biology to fluid mechanics and mass transfer as novel approaches to physiology models913. Insights Imaging 5(4):493506, Article Note the differential enhancement in the right ventricle outflow tract vs. main pulmonary trunk. Differential aortic enhancement can also be seen in patients with coarctation of aorta (Fig. Sagittal CECT MIP image demonstrates differential opacification of the aorta proximal and distal to the aortic coarctation with post-stenotic dilatation. This can be done immediately if there is another venous access or later after obtaining appropriate venous access. No pleural or pericardial effusion. With this end goal in mind, understanding the anatomy and physiology of the cardiovascular system as it pertains to contrast flow dynamics can serve as a useful starting point. Manifestations read more ) or in the intrahepatic terminal hepatic venules and hepatic sinusoids (sinusoidal obstruction syndrome Sinusoidal Obstruction Syndrome Hepatic sinusoidal obstruction syndrome is caused by endothelial injury, leading to nonthrombotic occlusion of the terminal hepatic venules and hepatic sinusoids, rather than of the hepatic read more , previously called veno-occlusive disease) but often occurs in both. In patients with small caliber access veins, a dual energy acquisition can be obtained. Privacy Street network theory of organization in nature. Notice the altered pattern of contrast flow. We deconstructed the liver as a canopy-to-canopy architecture of trees made of 2 trees running in parallel (the hepatic artery and the portal vein) combined with the hepatic vein tree. Lee J, Kim S, Lorente S, Bejan A. Vascularization with trees matched canopy to canopy: Diagonal channels with multiple sizes. Lower (4060KeV) monoenergetic reconstruction can be obtained to boost contrast opacification. 13), and when using prospective ECG triggered CTA (Fig. 1). 17 obtained after the ECMO circuit was put on minimal flow status for a short period (25s) to allow for near physiologic circulation. CTA shows contrast reflux into IVC and dependent hepatic veins and blood-contrast level in the IVC. In our approach, the liver becomes a multi-scale dendritic fluid network constituted of superimposed tree-shaped architectures that provides and drains the blood flow. Note the complete nonopacification of false lumen. We wrote in Table Table11 the diameter ratios at each generation level, their average value and standard deviation for the 3 flow configurations, calculated from the data provided in Refs. 1 for a bird-eye view. Conceptually, the liver vascularization can be seen as 2 trees matching canopy-to-canopy bathing a porous architecture made of lobules, as presented in Fig. The authors declare no competing interests. Delayed phasescan at 3min has been shown to be good in visualizing entire vasculature during recirculation, regardless of the intravenous route or surgical technique [28]. EXAMPLE REPORTING TEMPLATE WITH CHECKLIST: LOWER CHEST: Lung bases are clear. Considered a physiologic artifact, transient attenuation or interruption of the contrast bolus refers to disruption of the normal opacified contrast column secondary to return of unopacified venous blood via the inferior vena cava (IVC) in the setting of deep inspiration (Fig. Dynamic CTA, with the arm in neutral position and then in elevated positions (130 of hyperabduction with external rotation), can be used to evaluate TOS [17, 18]. Imaging pearl: Know the transit delay and scan acquisition time of the CT scanner. Although there are safety issues related to this such as the risk of catheter rupture, fragmentation, or thromboembolism, these devices can be safely used if appropriate precautions including manufacturer specifications are followed [34]. The work dealt with a surface with a round cross section. Imaging pearl: In patients with known heart failure, test bolus can be more useful in identifying time to peak enhancement, which can be delayed compared to contrast arrival time. Case study, Radiopaedia.org (Accessed on 01 May 2023) https://doi.org/10.53347/rID-66174. The channels length ratio of each tree is similar to the diameter ratio and follows the equipartition of thermodynamic imperfections principle. Bonfiglio A, Leungchavaphongse K, Repetto R, Siggers JH. In Eq. Garcea G, Maddern GJ. You can use Radiopaedia cases in a variety of ways to help you learn and teach. Finally the overall pressure loss is, The pressure loss along the sinusoids is phmh/6Lh/dh4 in the case of the hexagonal shape, and pcmh/4Lh/dc4 in the case of the square shape. The portal venous system drains the intestines, pancreas, and spleen with numerous collateral anastomoses to other venous beds of the abdomen. Coil embolisation of the varices was performed. No peripancreatic fluid. 1Department of Mechanical Engineering, Villanova University, Villanova, PA 19085 USA, 2Departamento de Fsica, Facultad de Ciencias, Universidad Nacional Autnoma de Mxico, Circuito Exterior S/N, Ciudad Universitaria, CP04510 Coyoacn, Ciudad de Mxico, Mexico, 3Centro Mdico 20 de Noviembre, ISSSTE,, Flix Cuevas 540, Del Valle Sur, Benito Jurez, CP03100 Ciudad de Mxico, Mexico. Contrast opacification is of the dependent vasculature only. Normal flow of intravenous contrast through a commonly used upper extremity venous access site follows a pattern; contrast flows first into the brachiocephalic vein, then into the superior vena cava, right atrium, right ventricle, pulmonary artery, pulmonary vein, left atrium, left ventricle, ultimately to opacify the ascending and then the descending aorta. Scanning Electron Microscope images of human liver reveal that the elemental system, the lobule, is entirely vascularized19. In a point-to-volume configuration the tree-shaped architecture exists because it is endowed with less friction losses compared to a radial flow distribution, just like in the river delta analogy. Our approach is based on the constructal law of design14. In the absence of more precise data, Eq. Delayed images can help in opacification of the lumen (Fig. 5 is a good pattern. By using low energy virtual monoenergetic images, the energy levels of which are closer to the K edge of iodine, the contrast signal is amplified which can potentially salvage some suboptimal studies. CT image during test bolus injection (a) with regions of interest over the ascending aorta (1), descending aorta (2) and pulmonary artery (3). Post-threshold delay needs to be increased when using a faster scanner to better opacify the non target vessels. According to the literature15,44,45, the average human liver has a volume of 1500 cm3, and contains 1020% of blood, while it possesses about 106 lobules. Indian J Radiol Imaging 20(2):150153, Tomasian A, Malik S, Shamsa K, Krishnam MS (2009) Congenital heart diseases: post-operative appearance on multi-detector CT-a pictorial essay. Considering Darcy flow through the porous elemental system (i.e. large respiratory effort, cardiac motion, and/or the patient physically shifting on the table), leading to premature, delayed or even no bolus triggering. There is progressively increasing use of CT scans in the emergency department (ED) in recent years [1]. This result is in good agreement with the anatomical data. PTT can be calculated by evaluating the time attenuation graph obtained from the test bolus (Fig. This is similar to contrast attenuation in SVC. Radiograph or CT topogram imaging of the affected limb following an extravasation event may be useful to determine the magnitude of infiltration and verify if compartmentation is present (Fig. Treatment read more due to a hypercoagulable state, a vessel wall lesion (eg, pylephlebitis, omphalitis), an adjacent lesion (eg, pancreatitis Overview of Pancreatitis Pancreatitis is classified as either acute or chronic. An electrical analogue of the entire human circulatory system. where K is the intrinsic permeability of the lobule. CECT shows marked left atrium enlargement (arrow) with mixing of opacified blood coming from pulmonary veins and non-opacificed blood from the left ventricle due to severe mitral regurgitation. Axial CTA shows moderate pericardial effusion and heterogeneous enhancement of descending aorta with blood contrast layering. Blood is then pushed out when reaching the center of the lobule through the central vein parallel to the portal triad. JBR-BTR 96(5):304307, Tsai PP, Chen JH, Huang JL, Shen WC (2002) Dependent pooling: a contrast-enhanced sign of cardiac arrest during CT. AJR Am J Roentgenol 178(5):10951099, Roth C, Sneider M, Bogot N, Todd M, Cronin P (2006) Dependent venous contrast pooling and layering: a sign of imminent cardiogenic shock. Cavopulmonary shunts that connect the caval and pulmonary circulation are performed in patients with single ventricle physiology. In conclusion, p/mdendriticp/mradial. 2023 BioMed Central Ltd unless otherwise stated. If g is the generation number (g may vary from one tree to another) than the total number of HA (or PV) outlets or HV inlets is ng=3g, with a splitting number n=3. The hepatic veins drain the liver into the inferior vena cava. AJR Am J Roentgenol 192(6):16621667, Shaqdan K, Aran S, Thrall J, Abujudeh H (2014) Incidence of contrast medium extravasation for CT and MRI in a large academic medical centre: a report on 502,391 injections. Yet, about 20years ago, A. Bejan25 proved that dendritic configurations can be predicted, and that they exist for a very specific purpose. Two images from a CTPE study obtained in a patient with tricuspid atresia and bidirectional cavopulmonary connection demonstrate poor opacification of right pulmonary artery and non-enhancement of left pulmonary artery (a). Careful interpretation of power injector graphs, location of region of interest to trigger the scan, and pattern of contrast flow can help determine the cause. Bethesda, MD 20894, Web Policies This phase allows more accurate estimation of the extent of the false lumen thrombus and slow flow. Correspondence to Use to remove results with certain terms For example, contrast enhancement of a distal chamber before adequate opacification of a proximal vessel/chamber is never normal. Review of the axial images in the upper abdomen (b) reveal contrast reflux into IVC, dependent hepatic veins, and a blood-contrast level in the IVC. Normal gallbladder morphology. This should not be confused with a thrombus. Pattern of opacification of non target vessels can be useful in understanding the hemodynamic status of the patient and correctly identifying life threatening conditions such as tamponade, heart failure, and asystole. Lucia U, Grisolia G, Astori MR. Constructal law analysis of Cl transport in eyes aqueous humor. Systems modeling of developmental vascular toxicity. Provides 80% of blood to the liver. Insights Imaging 8, 127140 (2017). Table Table11 provides the diameter ratio, the channel length ratio and the splitting number at each generation number. Their complexity often forces to reduce the hydrodynamic studies of the liver to its morphofunctional unit, the lobule23,24. Similarly, persistent enhancement of a proximal segment when most of the contrast has washed out from the distal segments is not normal. The Physics of Life: The Evolution of Everything. 3 predicts that the corresponding diameter ratio should be 31/30.69 in order to minimize the pumping power needed to push the blood in and out the liver. The liver vasculature makes its unique among the other organs as it is made of the superimposition of three main networks, two inlets and one outlet. The hepatic veins drain the liver into the inferior vena cava. When portal vein blood flow increases, hepatic artery flow decreases and vice versa (the hepatic arterial buffer response). This dual, reciprocally compensatory blood supply provides some protection from hepatic ischemia in healthy people. The hepatic artery (which is oxygen-rich) supplies the rest. Murray CD. AJR Am J Roentgenol 186(4):11161119, Jana M, Gamanagatti SR, Kumar A (2010) Case series: CT scan in cardiac arrest and imminent cardiogenic shock. Although the real incidence of cardiac arrest at the time of CT is not known, it is probably not rare [23]. Nevertheless, and following the work of Revellin et al.31, Hess-Murrays law remains valid even with a power-law model. Describing the lobules under the assumption of slices of highly vascularized hexagons represents a commonly admitted hypothesis. Recognize life threatening causes of altered contrast dynamics such as cardiac asystole. 3a), leak at the level of the hub (Fig. Splenomegaly is almost always secondary to other disorders. Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. The initial CECT (a) shows poor opacification of the pulmonary artery despite high density contrast material within the aorta and SVC because deep inspiration resulted in increased venous return from the IVC and dilution of the contrast bolus in the right heart (b) at the time of scanning. The results are di+1/di= 0.74, 0.70, and 0.59 for the hepatic arteria, the portal vein and the hepatic vein respectively according to Debbaut et al.19,29, while a ratio of 0.79 is obtained from the measurements provided by Ma et al.22. Sequential axial CT images (af) from a test bolus obtained at the level of main pulmonary artery. For a long time, such structures were considered as being the result of chance, i.e. In normal subjects, this is about 6.81.7s [6]. Miguel AF. Insights Imaging 5(6):731742, Liu KL, Wang YF, Chang YC, Huang SC, Chen SJ, Tsang YM et al (2014) Multislice CT scans in patients on extracorporeal membrane oxygenation: emphasis on hemodynamic changes and imaging pitfalls. Eur Radiol 19(12):29412949, Sandler KL, Markham LW, Mah ML, Byrum EP, Williams JR (2014) Optimizing CT angiography in patients with Fontan physiology: single-center experience of dual-site power injection. Axial CECT after injection of intravenous contrast in the left upper extremity shows a large filling defect in the left subclavian vein (arrows) and multiple venous collaterals in the left shoulder region. Saili KS, Franzosa JA, Baker NC, Ellis-Hutchings RG, Settivari RS, Carney EW, Spencer RM, Zurlinden TJ, Kleinstreuer NC, Li S, Xia M, Knudsen TB. 7a and b). The architecture was based on bifurcation patterns. All rights reserved. As indicated by precise anatomy analysis of the liver architecture1922, the hepatic artery, portal vein and hepatic vein networks are three-dimensional, highly nested, forming an extremely compact structure. The assembly of hexagonal shapes makes each hepatic artery and portal vein in contact with 3 lobules. this patient has a good deal of intrabdominal fat, which separates and surrounds structures, helping to see/differentiate better than in a thinner patient. 4b) [15]. In case of an access vein size and i.v. Earlier opacification of a distal chamber may be an indicator of intra or extra-cardiac shunt. Diffuse obstruction results in congestion of the sinusoids, hepatomegaly, portal hypertension Portal Hypertension Portal hypertension is elevated pressure in the portal vein. 2). Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The shape of the liver as a hemisphere of radius R. By the same token, the flow resistance ratio between the dendritic and radial configurations is: where L1 is the channel length corresponding to the first generation number. Note that the number of 6 branches is the limit for which the radial connections exhibited in Fig. Central veins of the thorax convey blood/contrast bolus to the right atrium. Mathematical modeling of the circulation in the liver lobule. J Am Soc Echocardiogr: Off Publ Am Soc Echocardiogr 23(7):685713, quiz 786-688, Article Hessheimer AJ, et al. 6). The total pressure difference between the inlet and the outlet of a lobule is given by, Another way to pave entirely the square domain represented in Fig. If we look into Fig. The canopy-to-canopy view of the liver vascular system. Teutsch HF. with minimum work, to deliver a fixed volume of fluid from one point to an infinite number of points (a volume or a surface). The current review article outlines normal and abnormal intravenous contrast dynamics, discusses how to recognize etiologies of non-diagnostic scans, and ultimately addresses techniques to overcome obstacles towards obtaining normal contrast opacification of the target vessel. When using a scanner with shorter acquisition time, non-target vessel enhancement may be less than expected and these vessels should be interpreted with caution. No abdominal aortic aneurysm. Unless the vessel is patent, additional studies should be performed with a contralateral upper extremity injection to permit adequate contrast opacification. Contrast opacification on thoracic CT angiography: challenges and solutions . It may be diffuse and is often related to alcohol, diabetes, certain drugs and medications, or obesity [16].Occasionally, there may be diffuse fatty infiltration in the liver with focal areas of sparing or focal areas of fatty deposition in an otherwise normal liver [46]. Perfusion characteristics of the human hepatic microcirculation based on three-dimensional reconstructions and computational fluid dynamic analysis. Non-target vessel opacification may hold key to underlying pathophysiology. VASCULATURE: Portal, splenic, and superior mesenteric veins are patent. Consequences read more. The study indicated that the tube length ratio (daughter tube length divided by mother tube length) for minimum pumping power was a constant of about 0.50 regardless the number of tubes connected to the center of the disk. Finally, the permeability of a lobule of volume V is, which, in view of the asymptotic value of fn, gives. WebA patent paraumbilical vein (PUV) is a frequent finding in patients with cirrhosis when studied by duplex Doppler ultrasound. Check for errors and try again. Use of delayed images after 30s can help differentiate soft plaque/thrombus from slow flow when dependent pooling is seen. 8600 Rockville Pike The scan is initiated as soon as the contrast enhancement threshold (predetermined threshold HU) is reached within the region of interest. Detailed measurements of the geometrical features of the human liver blood network are scarce.

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