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Contrast opacification is of the dependent vasculature only. In classic Fontan, the right atrium and the pulmonary artery are anastomosed. 12), extra-cardiac shunts such as patent ductus arteriosus, bronchial artery, or coronary artery fistulas (Fig. Contrast flow and enhancement patterns seen on thoracic CT angiography (CTA) can often be challenging and may often reveal more than is immediately apparent. volume8,pages 127140 (2017)Cite this article. 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]. Despite its dual blood supply, the liver, a metabolically active organ, can be injured by. The blood transport through the lobules behaves like a flow through a porous system which predicted overall permeability agrees with data available in the literature. 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. Blood is then pushed out when reaching the center of the lobule through the central vein parallel to the portal triad. 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. Non-diagnostic thoracic CTAs are frequently encountered in clinical practice. The data are from Refs16,21,28. Modify the injection protocol and post-threshold delay based on these factors. The planned flow rate of 5.4mL/s using an 18g IV exceeded the recommended maximum of 5.0cc/s. This way, what was initially a local fluid source becomes a distributed fluid source. Korean J Radiol: Off J Korean Radiol Soc 15(3):322329, Lidegran MK, Ringertz HG, Frenckner BP, Linden VB (2005) Chest and abdominal CT during extracorporeal membrane oxygenation: Clinical benefits in diagnosis and treatment. We are interested in predicting the geometrical features leading to the smallest overall pressure difference possible. In our previous works on engineered flow architectures26,33, a general expression of the pressure losses was derived as a function of the fluid volume V and a flow resistance factor fn that varies with the bifurcation level of the dendritic structures. 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. http://creativecommons.org/licenses/by/4.0/. 11). Urgent states, "How to Read an Abdominal CT" Chapter 1 Supplement, Normal gastrointestinal tract imaging examples, this is a CT of the Abdomen and Pelvis, Enterography protocol. If pain is the main symptom, we use cold compresses, and if the extravasation has occurred in a location where there is a higher likelihood of compartment syndrome, we use hot compresses. This is indicative of poor stroke volume from tamponade. Table Table11 provides the diameter ratio, the channel length ratio and the splitting number at each generation number. The lobules dimensions are also difficult to find in the literature. At the time the case was submitted for publication Michael P Hartung had no recorded disclosures. Clin Radiol 69(12):12641272, Article A test bolus is preferable to bolus tracking in patients with post-surgical repair of complex congenital heart diseases. Causes are most often systemic: Impaired hepatic read more ; focal ischemia can cause hepatic infarction or ischemic cholangiopathy Ischemic Cholangiopathy Ischemic cholangiopathy is focal damage to the biliary tree due to disrupted flow from the hepatic artery via the peribiliary arterial plexus. The CT technician subsequently called the radiologist to check the images and ask for a repeat injection after identifying abnormal contrast enhancement. The architecture was based on bifurcation patterns. The sinusoids are uniformly distributed throughout the entire liver volume, and constitute the hepatic microcirculation. This should be reviewed by the radiologist. Thanks to the constructal law we could predict the main geometrical features of the liver: This work establishes the theoretical bases that help to complete the understanding of the results of experimental work carried out since the last century on animal models, as well as the most recent ones on experimental models on silicon scaffolds, organs on chips, and scaffolds of decellularized organs. Hepatic vasculature: a conceptual review - PubMed Contrast opacifies the right portal vein secondary to backflow from hepatic vein into portal vein. 4a). J Vasc Surg 54(5):12511258, Trimarchi S, Tolenaar JL, Jonker FH, Murray B, Tsai TT, Eagle KA et al (2013) Importance of false lumen thrombosis in type B aortic dissection prognosis. 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. The liver is one of the most important organ of the human body. The outlet flow (hepatic vein) is located at the center of each lobule. Kim S, Lorente S, Bejan A. Vascularized materials: tree-shaped flow architectures matched canopy to canopy. There is controversy regarding the clinical significance of this finding. BNP was immediately obtained and was elevated at 23,000, echocardiogram obtained within the next 4h demonstrated a left ventricle EF of 22%, Mixing artifact in the left atrium in a patient with severe mitral regurgitation. The network was completely determined thanks to (i) the radius ratio between a daughter branch and a mother branch in accord with the Hess-Murrays law (di+1/di=2-1/3, where 2 was the number of daughter branches), and (ii) the connection angles between ducts at each bifurcation level. Pressure gradient measured during catheter angiography was 20mm Hg across the stenosis. The trusted provider of medical information since 1899, Overview of Vascular Disorders of the Liver, Last review/revision Jan 2022 | Modified Sep 2022. What does it mean to say portal and hepatic veins are An optimal, diagnostic thoracic CTA study is never obtained by accident. 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. Extension of Murrays law using a non-Newtonian model of blood flow. 14), there may be a delay between consecutive axial acquisitions which is exaggerated in the presence of irregular heart rate. The hepatic veins drain the liver into the inferior vena cava. Delayed images (90s) demonstrate complete opacification of both pulmonary arteries and the intracardiac Fontan (b, also see Movie 2). 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. The hepatic veins drain the liver into the inferior vena cava. Note the differential enhancement in the right ventricle outflow tract vs. main pulmonary trunk. 4b) [15]. Nearly all portal vein disorders obstruct portal vein blood flow and cause portal hypertension Portal Hypertension Portal hypertension is elevated pressure in the portal vein. PubMed Proc Staff Meet Mayo Clin 31(9):281287, CAS The mass flow rate that exits one hexagon is mh, and therefore the total mass flow rate through the square delimited by the dashed lines would be 16mh. Consider the laminar steady flow of a fluid through a dendritic network. Selection of the wrong target vessel, especially in the setting of complex vascular anatomy, and/or selection of an ROI which is too big or too small are common operator dependent errors. Here we do not consider the very first tube length ratio as no information is provided on the first duct length in Refs19,29. To confront the theoretical approach developed in this paper to experimental data, we rely on anatomic results provided by two different groups19,22,29. (See also Overview of the Spleen.) Terms and Conditions, Delayed phase scan only. In their 2005 paper, Wechsatol et al.33 documented the design of laminar dendritic networks on a fixed disc-shaped area. o [ pediatric abdominal pain ] Hepatic vein disorders can result in focal or diffuse venous obstruction. Blood vessels of abdomen and pelvis : Anatomy overview | Kenhub Diffuse obstruction results in congestion of the sinusoids, hepatomegaly, portal hypertension Portal Hypertension Portal hypertension is elevated pressure in the portal vein. 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. The objective of this work was to propose a framework aiming at predicting the hepatic blood circulation. The canopy-to-canopy view of the liver vascular system. This prompted initiation of cardiopulmonary resuscitation and calling the code team. If suboptimal contrast opacification of the target vessel is present, reimaging the patient with the arm in the neutral or adducted position should relieve the dynamic narrowing of the thoracic outlet, thereby improving opacification of the vessel (Fig. Why the bigger live longer and travel farther: animals, vehicles, rivers and the winds. Mixing artifacts in the true lumen of the descending aortic aneurysm with Type B aortic dissection which resolve on delayed phase acquisition. Hepatic vascular bed. Indeed, Fisher17 in 1954 showed experimentally that the volume of blood reaching the liver and somehow the "delivered pressure", have an evident impact on the regenerative stimulus of liver regeneration with 3 surgical variants of restitution of portal flow plus hepatectomy. In bolus tracking technique, only one injection is performed at the planned flow rate. PubMed Central In type B dissection, identification of false lumen thrombus can be overestimated by first pass CTA/MRA. Flashcards. Google Scholar, Remy-Jardin M, Doyen J, Remy J, Artaud D, Fribourg M, Duhamel A (1997) Functional anatomy of the thoracic outlet: evaluation with spiral CT. Radiology 205(3):843851. Studies have shown that vascular enhancement is superior with central venous catheter injections compared to peripheral route injections due to the short time to peak enhancement facilitated by shorter travel distance for contrast bolus. Therefore we write. J Comput Assist Tomogr 34(1):7581, Clough RE, Hussain T, Uribe S, Greil GF, Razavi R, Taylor PR et al (2011) A new method for quantification of false lumen thrombosis in aortic dissection using magnetic resonance imaging and a blood pool contrast agent. Chest pain is the second leading presenting symptom in ED patients (5.2%) [2], thus thoracic CT angiography (CTA) has become one of the most commonly ordered CTA in ED. Sagittal CECT MIP image demonstrates differential opacification of the aorta proximal and distal to the aortic coarctation with post-stenotic dilatation. Portal hypertension can also cause varices (abnormally enlarged blood vessels) in the esophagus or stomach that may become prone to bleeding. Contrast opacification on thoracic CT angiography: challenges and solutions, https://doi.org/10.1007/s13244-016-0524-3. AJR Am J Roentgenol 193(4):928940, Shuman WP, Branch KR, May JM, Mitsumori LM, Strote JN, Warren BH et al (2009) Whole-chest 64-MDCT of emergency department patients with nonspecific chest pain: Radiation dose and coronary artery image quality with prospective ECG triggering versus retrospective ECG gating. 7c). Some favor cold compresses to decrease pain at the extravasation site and others prefer warm compresses to improve blood flow to the extravasation site and increase absorption of the contrast from the tissues into the vasculature and lymphatics. {"url":"/signup-modal-props.json?lang=us"}, Hartung M, How to read a CT of the abdomen and pelvis. Here, Lh is the distance between the lobule center and its perimeter. Use to remove results with certain terms The portal vein and hepatic arteries form the liver's dual blood supply. Approximately 75% of hepatic blood flow is derived from the portal vein, while the remainder is from the hepatic arteries. [4] Unlike most veins, the portal vein does not drain into the heart. Virtual tissues in toxicology. The central veins, or hepatic veins (HV) collect the blood and lead it to the vena cava inferior. The modeling of the hepatic circulation has been a challenge for several decades. Our approach is based on the constructal law of design 1, 2, 3, 4. 8600 Rockville Pike 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). The hepatic artery provides oxygenated blood to the liver, while the portal vein brings deoxygenated blood; the two mix in the sinusoids. Created by. The hexagonal cross section shows 6 portal triads made of the bile duct, the portal vein and the hepatic artery. The inlet vasculature is made of the hepatic artery and the portal vein, the outlet vasculature is made of the hepatic vein. Understanding and controlling the liver portal pressure after surgery would be of the utmost importance to guarantee correct regeneration signals and prevent cell death18. Contrast opacification is of the dependent vasculature only. This would give a lobule volume of 1.5 mm3. The assembly of lobules constitutes a functionalized porous medium which must allow the mixing of the oxygenated blood from the hepatic artery and the deoxygenated blood from the portal vein. 2). Once mixed the blood is pushed into the hepatic vein. Springer Nature. Portal, splenic, superior mesenteric veins, Visceral arteries (celiac, splenic, common hepatic, renal, SMA, IMA), Iliac, pelvic, and femoral arteries and veins, Upper abdomen (gastrohepatic ligament, celiac, portocaval, porta hepatis). Axial CTA shows moderate pericardial effusion and heterogeneous enhancement of descending aorta with blood contrast layering. Wechsatol W, Bejan A, Lorente S. Tree-shaped flow architectures: strategies for increasing optimization speed and accuracy. Inclusion in an NLM database does not imply endorsement of, or agreement with, Secondary signs of venous stenosis include dynamic collateral vessel filling and distal venous thrombus in chronic cases (Fig. Below are links to the electronic supplementary material. Bolus tracking technique for identification of contrast arrival. Such theoretical framework may be useful in the design of perfusion models both at micro and macro levels on the way to perfecting a functional prediction in the new coordinated and multidisciplinary efforts of regenerative medicine between other multiple physical scenarios. Two graphs are generated by the power injector, which plot the change in pressure over time and flow rate of the injection over time (3 A, B). The entire volume of the lobules is fixed because the blood volume is fixed. Yet, about 20years ago, A. Bejan25 proved that dendritic configurations can be predicted, and that they exist for a very specific purpose. 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. No ascites. Therefore, because the total mass flow rate is a constant, the mass flow rate per element must continue to be mh. sharing sensitive information, make sure youre on a federal The modular microarchitecture of human liver. There may be more than one type of CT scanner within the same hospital system. 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. WebUltrasound demonstrated a sonographically normal liver without nodularity or cirrhosis and patent hepatic vasculature ( Fig. PANCREAS: Normal morphology and enhancement. The sinusoids are Glenn shunt is performed as the second stage of surgical repair and involves anastomosis between the SVC and the right pulmonary artery, which can either be unidirectional or bidirectional. The hepatic artery may be occluded Hepatic Artery Occlusion Causes of hepatic artery occlusion include thrombosis (eg, due to hypercoagulability disorders, severe arteriosclerosis, or vasculitis), emboli (eg, due to endocarditis, tumors, therapeutic read more . All rights reserved. 5a). This result is in agreement with the literature as the radial and tangential permeability of a lobule were estimated to be about 1.5 1014 m2 in Ref46, while Ref11. Traditionally, ECG gated CT/MR have been used to define cardiac chamber enlargement. AJR Am J Roentgenol 194(4):912919, Bae KT (2005) Test-bolus versus bolus-tracking techniques for CT angiographic timing. The minimum pressure difference is obtained by minimizing p for the fixed volume V. The corresponding diameter ratio is given by31: As the splitting number is n = 3 on an average, Eq. Mathematical modeling of the circulation in the liver lobule. The liver has a dual blood supply. PubMed The hepatic artery brings oxygenated blood. Ma R, et al. The IVCs job is to return blood to the heart from the lower half of the body, including the feet, legs, thighs, pelvis, and abdomen. Radiographics 26(6):17351750. 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]. In our experience, slowing the flow of the circuit to the minimal flow rate that would prevent thrombus formation for the duration of the scan (1520s) has worked well in cases of suspected pulmonary embolism (Fig. Central venous catheters are often used for contrast injection. The iliac arteries branch off of the bottom of the aorta, the large artery coming out of the top of the heart. Please confirm that you are a health care professional. The lobules are represented classically by prismatic volumes of hexagonal cross section with one triad made of the hepatic artery, the portal vein and the bile duct at each of the 6 hexagon corners, and a central vein along the axis of the lobule. Vasculature Contrast 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. Specific vascular lesions may occur in the hepatic artery, hepatic vein, or portal vein. No body wall masses. Fisher B, Updegraff H. Effect of increased hepatic blood flow upon liver regeneration. Similarly, persistent enhancement of a proximal segment when most of the contrast has washed out from the distal segments is not normal. Insights Imaging 8, 127140 (2017). Hepatic vascular shunts The shape of the liver is assumed to be a hemisphere with a radius R, the center of which being located at the level of the blood inlet (Fig. Consequences read more , reduced portal blood flow, ascites Ascites Ascites is free fluid in the peritoneal cavity. Somatostatin and the Small-For-Size Liver. WebHepatic vasculature: a conceptual review Author Abstract The hepatic circulation is reviewed with emphasis on the role of hepatic blood vessels in hepatic and homeostatic Teutsch HF. We demonstrate that the dendritic nature of the hepatic artery, portal vein and hepatic vein can be predicted, together with their geometrical features (diameter ratio, duct length ratio) as the entire blood flow architectures follow the principle of equipartition of imperfections. Demondion X, Herbinet P, Van Sint Jan S, Boutry N, Chantelot C, Cotten A (2006) Imaging assessment of thoracic outlet syndrome. 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. Total cavopulmonary connection involves a Glenn shunt connecting SVC to the right PA and Fontan shunt connecting IVC to left PA. CT angiography in these patients to visualize the pulmonary arteries or the conduits themselves is challenging since the SVC flow is directed to the right lung and the IVC flow is directed to the lung (Fig. As each square element is in contact with 3 other ones, the mass flow rate through the duct of diameter d and length Ld must be mh. Hess, W. R. Das Prinzip des kleinsten Kraftverbrauches im Dienste hmodynamischer Forschung. where K is the intrinsic permeability of the lobule. Visceral arteries are patent. Wambaugh J, Shah I. Simulating microdosimetry in a virtual hepatic lobule. Street network theory of organization in nature. Debbaut C, et al. Necrosis Interpretation of these graphs can help identify the cause of a nondiagnostic scan in the first place and what parameters need to be changed before we plan a reinjection. A 3D porous media liver lobule model: the importance of vascular septa and anisotropic permeability for homogeneous perfusion. On an average, the measured splitting number is 2.76 for the hepatic artery, 2.80 for the portal vein, and 3.22 for the hepatic vein, which translated into the integer n = 3. White D, Coombe D, Rezania V, Tuszynski J. The robustness of the permeability of constructal tree-shaped fissures. WebPortal hypertension is a term used to describe elevated pressures in the portal venous system (a major vein that leads to the liver). Hepatic artery. The thinner channels form the canopy of the HA and PV trees and irrigate the lobules which behave like a porous system. Also note the differential enhancement in descending aorta. (See also Overview of Vascular Disorders of the Liver.) The flow path is represented on the left hand side of Fig. The blood flow path is represented by the arrows. one lobule), the average velocity of the blood flowing to the central vein is. Regardless of the post-extravasation treatment method, patients should be evaluated by the radiologist. Rezania V, Marsh R, Coombe D, Tuszynski J. Non-target vessel opacification may hold key to underlying pathophysiology. Peak flow rate needed varies on the indication for the CTA: preferred flow rate for pulmonary artery CTA is 35cc/s [10], for aortic evaluation is > 3cc/s [11], and for coronary artery assessment is>5cc/s [12] (Table 3). 4 with the definition of the fluid volume Vd12L1i=0g3i/3ki, we finally write: We demonstrated previously that the most efficient flow architectures are the ones featuring equipartition of thermodynamics imperfections32. Br J Radiol 84(999):197203, Article Each tree architecture is composed of a main trunk subdivided into smaller and smaller braches. Normal sequence of enhancement follows right atrium, right ventricle, pulmonary artery, pulmonary vein, left atrium, left ventricle, and aorta. Anatomically based simulation of hepatic perfusion in the human liver. J Thorac Imaging 19(1):17, Wittram C, Yoo AJ (2007) Transient interruption of contrast on CT pulmonary angiography: proof of mechanism. Cirrhosis Cirrhosis Cirrhosis is a late stage of hepatic fibrosis that has resulted in widespread distortion of normal hepatic architecture. Its generic expression is. Delayed phase acquisition is recommended for a more accurate estimation of true extent of false lumen thrombus vs. slow flow. in cases of a pulmonary artery CTA, this implies delayed aortic opacification.