Demondion X, Herbinet P, Van Sint Jan S, Boutry N, Chantelot C, Cotten A (2006) Imaging assessment of thoracic outlet syndrome. Here we do not consider the bile canal. The hepatic artery originates from the common hepatic artery and divides into the right and left hepatic arteries. This canopy-to-canopy feature is complemented by a porous medium, the lobules. Numerical simulation of the hepatic circulation. There is progressively increasing use of CT scans in the emergency department (ED) in recent years [1]. The liver is not only the largest organ in the body but also the one playing one of the most important role in the human metabolism as it is in charge of transforming toxic substances in the body. 1). Modify the injection protocol and post-threshold delay based on these factors. WebFatty deposition in the liver is common and has many imaging manifestations. Symptoms usually result from abdominal distention. The inlet flow comes from the hepatic artery and the portal vein constituting the triad (the third element being the bile canal). 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. A less dramatic, but equally important observation may be seen in patients with congestive heart failure with resultant poor or no opacification of left cardiac chambers and aorta during a CT pulmonary angiogram (Fig. The most common cause is portal hypertension. Insufficient venous drainage may result from focal or diffuse obstruction or from right-sided heart failure, as in congestive hepatopathy Congestive Hepatopathy Congestive hepatopathy is diffuse venous congestion within the liver that results from right-sided heart failure (usually due to a cardiomyopathy, tricuspid regurgitation, mitral insufficiency read more . Radiology 256(1):3261. Lobe segmentation relies on other segmentations, including the lungs, the lung airways and vasculature. Shah I, Wambaugh J. River basin in a liver lobule. This is important since there is a higher risk of pulmonary thromboembolism (319%) in these patients [27]. Its generic expression is. Portal vein. Use OR to account for alternate terms Yet, about 20years ago, A. Bejan25 proved that dendritic configurations can be predicted, and that they exist for a very specific purpose. Patent and flow direction. Each central vein of a hexagon receives mh/6 from the 6 triads distant of Lh from the central vein (the hexagon is made of 6 equilateral triangles of side Lh). 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). Models range from the entire circulatory architecture6 to the hepatic micro circulation7,8. Patent paraumbilical and abdominal subcutaneous veins are found frequently as collaterals in patients due to portal hypertension, mainly associated with liver Hepatic vascular shunts Moreno, R., Segers, P. & Debbaut, C. Estimation of the permeability tensor of the microvasculature of the liver through fabric tensors. Flashcards. An optimal, diagnostic thoracic CTA study is never obtained by accident. The blood distribution within the lobule is similar to a reverse river basin connecting rivulets to a central sink. J Comput Assist Tomogr 39(5):794796, Rudski LG, Lai WW, Afilalo J, Hua L, Handschumacher MD, Chandrasekaran K et al (2010) Guidelines for the echocardiographic assessment of the right heart in adults: a report from the American Society of Echocardiography endorsed by the European Association of Echocardiography, a registered branch of the European Society of Cardiology, and the Canadian Society of Echocardiography. Match. This should not be confused with a thrombus. A test bolus is preferable to bolus tracking in patients with post-surgical repair of complex congenital heart diseases. 5 this means that 31/3k = 1, or said in other words: The averaged measured channel length ratio is 0.66, 0.72 and 0.66 for respectively HA, PV and HV. 4, we see that the square image is made of about 16 hexagonal shapes of side Lh. 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. VASCULATURE: Portal, splenic, and superior mesenteric veins are patent. 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). Unless the vessel is patent, additional studies should be performed with a contralateral upper extremity injection to permit adequate contrast opacification. The architecture was based on bifurcation patterns. Acute findings (SBO, appy, diverticulitis, enteritis, colitis, appendagitis, etc), Distal esophagus and gastroesophageal junction, Small and large bowel caliber, wall thickness, enhancement, Hernias (ventral, umbilical, spigellian, parastomal, lumbar, inguinal, femoral, obturator, sciatic). liver Imaging pearl: In patients with known aortic aneurysm, ROI for test bolus or bolus tracking should be placed in that portion of the aorta which has the largest diameter. 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. Toward an optimal design principle in symmetric and asymmetric tree flow networks. Contrast opacification is of the dependent vasculature only. We observe the patient in the radiology department for at least 1h to ensure that there are no new symptoms, such as pain or numbness to suggest development of compartment syndrome. The Physics of Life: The Evolution of Everything. Learn. Their complexity often forces to reduce the hydrodynamic studies of the liver to its morphofunctional unit, the lobule23,24. 3. To confront the theoretical approach developed in this paper to experimental data, we rely on anatomic results provided by two different groups19,22,29. The necessary pumping power is provided by the heart, and is proportional to mp. 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. These are, however, not commonly seen in left atrium or left ventricle, and whenever seen should be considered abnormal (Fig. Configurations of trees matching canopy-to-canopy were already presented by our group in the context of engineering applications3739. Wechsatol W, Bejan A, Lorente S. Tree-shaped flow architectures: strategies for increasing optimization speed and accuracy. Portal Venous System 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. Although the real incidence of cardiac arrest at the time of CT is not known, it is probably not rare [23]. Mosharaf-Dehkordi M. A fully coupled porous media and channels flow approach for simulation of blood and bile flow through the liver lobules. In the case of the tree networks that compose the liver vascular system, the generation number is about 20. In patients unable to hold breath, alternatively a free breathing high pitch flash CTA may be obtained [21] (Fig. Lobules of the liver paving the entire available domain. Hopkins Medicine Diagnosis is based on physical examination and read more , and splenomegaly Splenomegaly Splenomegaly is abnormal enlargement of the spleen. 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. There may be more than one type of CT scanner within the same hospital system. Sequential contrast opacification of central veins and cardiac chambers can be observed when bolus timing technique is used to identify contrast arrival. When present, these findings should raise the suspicion of altered flow dynamics including underlying intra- or extra-cardiac shunt. Contrast pressure and flow graphs often contain useful information regarding the etiology of a non-diagnostic scan. Uncommonly, aneurysms Hepatic Artery Aneurysms Aneurysms of the hepatic artery are uncommon. The sinusoids are Below are links to the electronic supplementary material. Insights Imaging 8, 127140 (2017). The term (g+1)3/3g is lower than 1 as soon as the generation number reaches a value of 5, while L1 Malley-Ernewein, A. Curr Probl Diagn Radiol 41(2):5255, Peet RM, Henriksen JD, Anderson TP, Martin GM (1956) Thoracic-outlet syndrome: evaluation of a therapeutic exercise program. 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. Siggers JH, Leungchavaphongse K, Ho CH, Repetto R. Mathematical model of blood and interstitial flow and lymph production in the liver. 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. Chronic pancreatitis is characterized by histologic read more , tumor), or congenital atresia of the portal vein, Intrahepaticeg, microvascular portal vein obstruction as occurs in schistosomiasis Schistosomiasis Schistosomiasis is infection with blood flukes of the genus Schistosoma, which are acquired transcutaneously by swimming or wading in contaminated freshwater. 12), extra-cardiac shunts such as patent ductus arteriosus, bronchial artery, or coronary artery fistulas (Fig. Imaging Pearl: Different approaches have been suggested to perform contrast-enhanced CTA in patients on ECMO: injection into the arterial cannula of the ECMO after the membrane oxygenator or into the venous line distal to the membrane oxygenator [33]. Cirrhosis Cirrhosis Cirrhosis is a late stage of hepatic fibrosis that has resulted in widespread distortion of normal hepatic architecture. Differential enhancement of false lumen of an aortic dissection can also be due to delayed opacification due to higher inherent luminal pressures. Delayed images (90s) demonstrate complete opacification of both pulmonary arteries and the intracardiac Fontan (b, also see Movie 2). 6). Debbaut C, et al. In. Sagittal CECT MIP image demonstrates differential opacification of the aorta proximal and distal to the aortic coarctation with post-stenotic dilatation. Other severe Google Scholar, Schaverien MV, Evison D, McCulley SJ (2008) Management of large volume CT contrast medium extravasation injury: technical refinement and literature review. This is called the transit delay (Table 2) and varies from patient to patient and scanner to scanner. 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. 3) and length ratios (Eq. 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. brought the medical vision to the work. Hepatic portal vein. Contrast opacification on thoracic CT angiography: challenges and solutions . Angiography is the test of choice in the evaluation of possible vascular complications. Differential enhancement of pulmonary arteries during a pulmonary artery CTA can be seen in patients with Fontan circulation (Fig. This can help in planning a reinjection and obtain a diagnostic scan. The two major venous plexuses that are The vascular system and the cost of blood volume. Case study, Radiopaedia.org (Accessed on 01 May 2023) https://doi.org/10.53347/rID-66174. 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. Portal hypertension can also cause varices (abnormally enlarged blood vessels) in the esophagus or stomach that may become prone to bleeding. 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. The measured diameters (blue dots) and lengths (red squares) ratios inside the liver as a function of the splitting generation number, for the hepatic artery HA, the portal vein PV and the hepatic vein HV. 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. Ultrasound abdomen: ultrasound of liver identifies a patent portal 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. Contrast extravasation should be considered if the power injector demonstrates unexpected rapid drop in pressure or exceeds the pressure limit with sudden decrease in flow rate before the full volume of contrast is administered to the patient. CTA shows contrast reflux into IVC and dependent hepatic veins and blood-contrast level in the IVC. The modular microarchitecture of human liver. From one source, the blood not only invades the sinusoids network in the broad direction of the central vein, but it must also flow along the hexagon periphery at mid-distance from the two neighboring sources. (MOV 563 kb), Delayed phase axial CT from a CTPE study obtained in a patient with tricuspid atresia and bidirectional cavopulmonary connection demonstrate complete opacification of both pulmonary arteries and the intracardiac Fontan. Patients at risk for contrast extravasation include infants and small children, elderly, uncooperative, and unconscious patients, as they may not be able to communicate or complain of pain reliably during injection. 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. Thoracic venous outlet obstruction of the left subclavian vein with the left arm raised for CTPA, which subsequently resolves upon positioning the arm down at the side. Why a hexagon? We showed that the global flow resistance decreases as the number of bathed elements connected to the trees increases. Axial CTA images from the same patient as in Fig. 6) in order to spend less pumping power for the same fluid volume26. 2). There is insufficient opacification of the pulmonary circulation due to siphoning of contrast by ECMO. Wechsatol W, Lorente S, Bejan A. Optimal tree-shaped networks for fluid flow in a disc-shaped body. We gathered the values of fn from Wechsatol et al.33 They are 13.16, 16.31, 18.67, 20.5, 21.8 and 22.6 for n=2 to 7 respectively, which means that for increasing pairing levels, fn reaches an asymptote close to 25. 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. PubMed The liver is one of the most important organ of the human body. Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. An official website of the United States government. We note that each source is in charge of 1/6th of the hexagonal lobule cross section. Attenuation-time graph corresponding to the regions of interest (b) shows prolonged pulmonary circulation time of 16s in this patient due to aortic stenosis (normal pulmonary transit time is approximately 79s). Chaturvedi, A., Oppenheimer, D., Rajiah, P. et al. Cavopulmonary shunts that connect the caval and pulmonary circulation are performed in patients with single ventricle physiology. However, recent literature has suggested threshold measurements to identify left atrial enlargement (transverse diameter: 73mm, anteroposterior diameter: 43mm) [3] and left ventricle enlargement (56mm) [4] on a non-ECG gated CTA. Ricken, T., Waschinsky, N. & Werner, D. Simulation of steatosis zonation in liver lobuleA continuum mechanical bi-scale, tri-phasic, multi-component approach. On another hand, Debbaut et al.46 reported a value of 0.134 mm3 for 3 human liver lobules. 4b) [15]. In addition, there are some life-threatening findings, which unless sought for, may remain hidden in plain sight. The planned flow rate of 5.4mL/s using an 18g IV exceeded the recommended maximum of 5.0cc/s. Landes, G. Einige Untersuchungen an elektrischen Analogieschaltungen zum Kreislaufsystem. 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. Google Scholar, Litmanovich D, Bankier AA, Cantin L, Raptopoulos V, Boiselle PM (2009) CT and MRI in diseases of the aorta. Here we do not consider the very first tube length ratio as no information is provided on the first duct length in Refs19,29. Numerical modeling of oxygen availability in the AMC bioartificial liver. o [teenager OR adolescent ], , MD, University of Colorado School of Medicine. Fontan shunt is performed as the third stage of ventricular repair and involves anastomosis between the IVC and the left pulmonary artery. Br J Radiol 84(999):197203, Article Axial (a) and coronal reformatted pulmonary CTA (b) subsequently demonstrates a large central pulmonary embolism. PubMed The flow resistance created in the case of a dendritic design is given by. 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. The overall pressure loss from the hexagon rim to the central vein is the sum of the pressure losses along the branches of the flow dendritic pathway. reports a lobule permeability of 4.8 109 m2. There may be retrograde opacification of IVC, hepatic veins, and even portal vein with dependent pooling of the contrast forming a blood-contrast level (Movie 1) [24]. Hepatic vein disorders can result in focal or diffuse venous obstruction. 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. For the blood to flow through the entire body, a pump is needed. In Eq. The hepatic artery, portal vein and hepatic vein form a compact three-dimensional dendritic architecture within the liver. The link you have selected will take you to a third-party website. Pressure gradient measured during catheter angiography was 20mm Hg across the stenosis. LIVER AND BILIARY: Normal liver morphology and enhancement. The pulmonary artery to ascending aorta transit time (PTT) is a key circulatory parameter that can affect target, as well as non-target vessel opacification on a thoracic CTA. PubMedGoogle Scholar. Ultrasound Assessment of the Hepatic Vasculature Repeat injection with placement of ROI in true lumen resulted in adequate evaluation of dissection. (See also Overview of Vascular Disorders of the Liver.) We studied 50 patients with cirrhosis and portal hypertension as evidenced by the demonstration of esophageal varices on endoscopy. Contrast opacifies the right portal vein secondary to backflow from hepatic vein into portal vein. Nevertheless considering that the hexagonal shape is close to the circle shape, the same expression was used in this work to predict the order of magnitude of the lobule permeability. Tree-shaped architectures are configurations that correspond to a point-to-volume flow. From vascular corrosion cast to electrical analog model for the study of human liver hemodynamics and perfusion. 4 would be to use squared shaped lobules of side LS with AS=LS2. Imaging pearl: Know the transit delay and scan acquisition time of the CT scanner. Extravasation of contrast material, in which contrast medium is injected outside the intended vessel, is an infrequent, but well known complicationof CTA (Fig. Lucia U, Grisolia G, Astori MR. Constructal law analysis of Cl transport in eyes aqueous humor. Contrast extravasation rates during CT imaging range between 0.1 and 0.9%, with an average rate of 0.4% [13, 14]. J Plast Reconstr Aesthet Surg 61(5):562565, discussion 565, Tonolini M, Campari A, Bianco R (2012) Extravasation of radiographic contrast media: prevention, diagnosis, and treatment. 6. In addition, there are some life-threatening findings, which unless sought for, may remain hidden in plain sight. PANCREAS: Normal morphology and enhancement. Also, contrast pressure and flow graphs obtained with the CTA often contain useful information regarding the etiology of a non-diagnostic scan (Table 1). For the right atrium, usually the normal diameters suggested by echocardiography on four-chamber view have been used: right atrium (long-axis dimensions 3.45.3cm and 2.64.4cm for short axis) and for right ventricle (basal dimensions 3.94.5cm and longitudinal dimension 89.1cm) [5]. PTT can be calculated by evaluating the time attenuation graph obtained from the test bolus (Fig. 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. No pleural or pericardial effusion. In addition, attempts to remove the extravasated contrast via aspiration have not been shown to be consistently beneficial. Kim S, Lorente S, Bejan A. Vascularized materials: tree-shaped flow architectures matched canopy to canopy. 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. PubMed Central Kocher KE, Meurer WJ, Fazel R, Scott PA, Krumholz HM, Nallamothu BK (2011) National trends in use of computed tomography in the emergency department. WebPortal hypertension is a term used to describe elevated pressures in the portal venous system (a major vein that leads to the liver). 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.
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