In classic Fontan, the right atrium and the pulmonary artery are anastomosed. The most common cause is portal hypertension. Each tree architecture is composed of a main trunk subdivided into smaller and smaller braches. 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. a Extravasation of intravenously injected contrast material. The two inlet networks, namely the hepatic artery (HA) and the portal vein (PV), run in parallel. PubMed Central In a patient with contrast flow rate above the recommended maximum (a). 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. WebAngiogram showing a patent TIPS shunt in the liver between the right hepatic vein and the right portal vein. REPRODUCTIVE ORGANS: Normal size and contours of the prostate and seminal vesicles. The sinusoids together with the hepatocyte cords form the smallest units of the liver: the lobules. http://creativecommons.org/licenses/by/4.0/. Splenomegaly is almost always secondary to other disorders. 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. Calling Ah the area of the hexagon, we have Ah=332Lh2. The distribution of contrast medium is now being determined by the push from the power injector and the viscosity of the contrast medium. The proximal end of the stent extends into the right atrium in this patient, who was not a suitable candidate for liver transplantation. The peak flow rate that can be achieved also depends on the size of the access vein [9] (Table 4). & Lorente, S. Analysis of thermochemical energy storage in an elemental configuration. 7c). Match. 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. the slice thickness is 2.5 mm. Insights Imaging 5(4):493506, Article Extravasation of contrast material, in which contrast medium is injected outside the intended vessel, is an infrequent, but well known complicationof CTA (Fig. brought the medical vision to the work. Graphs and tables from the power injector: pressure-time and flow rate-time graphs. Check for errors and try again. WebThe iliac arteries are blood vessels that provide blood to the legs, pelvis, reproductive organs and other organs in the pelvic area. Based on the previous assumptions, the friction losses and total volume vary as. WebThe hepatic artery (which is oxygen-rich) supplies the rest. The pathophysiologic mechanism of this artifact is secondary to the normal variable inflow of blood to the right heart during inspiration. View Michael P Hartung's current disclosures, see full revision history and disclosures, How to read a CT of the abdomen and pelvis, "How to Read an Abdominal CT" Chapter 2 Supplement, #14 Gastrointestinal tract. 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, portal vein and hepatic vein form a compact three-dimensional dendritic architecture within the liver. VASCULATURE: Portal, splenic, and superior mesenteric veins are patent. The entire network is similar to a river delta, except that in the case of the lobule the fluid flows in the reverse direction as in the river basin. Other severe Hepatic infarction results from hepatic artery disorders. Traditionally, ECG gated CT/MR have been used to define cardiac chamber enlargement. From vascular corrosion cast to electrical analog model for the study of human liver hemodynamics and perfusion. The theory is compared with good agreement to anatomical data from the literature. This way, what was initially a local fluid source becomes a distributed fluid source. Learn. Systems modeling of developmental vascular toxicity. 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. If contrast is suboptimal, sometimes it can be amplified by using virtual monoenergetic images from a dual energy scanner. The authors declare no competing interests. Axial CTA images from the same patient as in Fig. In addition, there are some life-threatening findings, which unless sought for, may remain hidden in plain sight. Mosa M, Labat M, Lorente S. Role of flow architectures on the design of radiant cooling panels, a constructal approach. 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. In. and transmitted securely. 5. River basin in a liver lobule. 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. 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. In bolus tracking technique, only one injection is performed at the planned flow rate. Anatomically based simulation of hepatic perfusion in the human liver. MUSCULOSKELETAL: No aggressive osseous lesion. No solid masses. 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]. Patent mesenteric vasculature and an antimesenteric pattern of involvement, along with reports of hypercoagulability in patients with COVID-19, suggest the necrosis occurred as a result of microvascular thrombosis and associated inflammation. 1 for a bird-eye view. This can be done immediately if there is another venous access or later after obtaining appropriate venous access. 10). The planned flow rate of 5.4mL/s using an 18g IV exceeded the recommended maximum of 5.0cc/s. PubMed developed the theory, M.H. 16,17 If originating from the right branch of the portal vein, these shunts drain directly into the caudal vena cava. Although the real incidence of cardiac arrest at the time of CT is not known, it is probably not rare [23]. 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 inlet flow comes from the hepatic artery and the portal vein constituting the triad (the third element being the bile canal). Somatostatin and the Small-For-Size Liver. Diffuse ischemia can cause ischemic hepatitis Ischemic Hepatitis Ischemic hepatitis is diffuse liver damage due to an inadequate blood or oxygen supply. The results are gathered in Fig. Diagnosis is based on ultrasonography. 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. 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. 2). Unable to process the form. Learn more about the Merck Manuals and our commitment to Global Medical Knowledge. The three tree-shaped architectures correspond to a volume-to-point flow. Contrast opacification is of the dependent vasculature only. 14). Causes of splenomegaly are myriad, as are the read more . 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. The assembly of hexagonal shapes makes each hepatic artery and portal vein in contact with 3 lobules. 12b, Movie 2) [26]. Patient with cardiac arrest at the time of CTA for acute aortic syndrome. In conclusion, each blood architecture corresponds to a system allowing a point-to-volume (or volume-to-point) fluid distribution for minimum pumping work. Any disruption of the above-described normal sequence of events should be treated with suspicion. volume8,pages 127140 (2017)Cite this article. Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. 18 gives a permeability K ranging between 3 1010 m2 and 9 1012 m2. 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). 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. 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. There may be more than one type of CT scanner within the same hospital system. A non-diagnostic CTA following the initial contrast injection can be secondary to many causes; these include both extrinsic factors, such as injection technique/equipment failure (iv cannula, power injector), and intrinsic, patient-related factors. The modular microarchitecture of human liver. The liver is one of the most important organ of the human body. We do not control or have responsibility for the content of any third-party site. 9). Mareels G, Poyck PPC, Eloot S, Verdonck PR. Differential enhancement of ascending and descending aorta during a thoracic aortic CTA can be seen by using a prospectively triggered acquisition, coarctation, large aneurysms, and dissections. Diffuse obstruction results in congestion of the sinusoids, hepatomegaly, portal hypertension Portal Hypertension Portal hypertension is elevated pressure in the portal vein. 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. FOIA Google Scholar, Litmanovich D, Bankier AA, Cantin L, Raptopoulos V, Boiselle PM (2009) CT and MRI in diseases of the aorta. The .gov means its official. 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. 1) but failed to visualize the gallbladder (Fig. A delayed phase, 40s acquisition can help in identifying any thrombus, vegetation, or fibrin sheath attached to the catheter. Br J Radiol 84(999):197203, Article Patients receiving chemotherapy also have an increased risk due to fragile, damaged, and often small caliber vessels. To confront the theoretical approach developed in this paper to experimental data, we rely on anatomic results provided by two different groups19,22,29. Pater L, Berg J. The iliac arteries branch off of the bottom of the aorta, the large artery coming out of the top of the heart. 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. In normal subjects, this is about 6.81.7s [6]. Regardless of the post-extravasation treatment method, patients should be evaluated by the radiologist. GI TRACT AND PERITONEUM: Normal morphology of the stomach and duodenum. CTA shows contrast reflux into IVC and dependent hepatic veins and blood-contrast level in the IVC. Incidentally, the deterministic structure of the body fluid networks was highlighted in the early twentieth century by respectively Hess27 and Murray28 who came to the conclusion that the diameter ratio between mother and daughter branches has a unique value. The blood mixes along each of the sinusoids, which are mainly perpendicular to the portal triad. Clin Radiol 69(12):e562e567, Park EA, Lee W, Chung SY, Yin YH, Chung JW, Park JH (2010) Optimal scan timing and intravenous route for contrast-enhanced computed tomography in patients after Fontan operation. Yet, about 20years ago, A. Bejan25 proved that dendritic configurations can be predicted, and that they exist for a very specific purpose. Consider the laminar steady flow of a fluid through a dendritic network. Street network theory of organization in nature. Imaging pearl: Check the access vein and access cannula before initiating contrast injection. Notice the altered pattern of contrast flow. In their 2005 paper, Wechsatol et al.33 documented the design of laminar dendritic networks on a fixed disc-shaped area. 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 . The objective of this work was to propose a framework aiming at predicting the hepatic blood circulation. Thoracic venous outlet obstruction should be considered when extensive collateral vessel filling is seen on the side of contrast administration when the patients arms are raised. Inclusion in an NLM database does not imply endorsement of, or agreement with, Suzuki K, et al. Miguel AF. Missing is a theoretical approach, based on first principles, that would allow to predict the flow architecture of the hepatic circulation: liver transplant, or liver resection as a treatment for liver tumors, may end up to liver failure with disastrous consequences when the change in blood pressure is not controlled1416. The study is otherwise normal. 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). 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. Describing the lobules under the assumption of slices of highly vascularized hexagons represents a commonly admitted hypothesis. Below are links to the electronic supplementary material. Understanding the type of CT scanner used is important as scan parameters such as transit time, acquisition time, applied kVp and mAs may differ between scanners. Demondion X, Herbinet P, Van Sint Jan S, Boutry N, Chantelot C, Cotten A (2006) Imaging assessment of thoracic outlet syndrome. The lobule is considered to be the liver functional unit, the elemental system. Configurations of trees matching canopy-to-canopy were already presented by our group in the context of engineering applications3739. The lobules which constitute the designed porous medium have a highly regular design. S.L. 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. 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. 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. Control of hepatic blood flow Consequences read more. The latter is a three-dimensional network forming a lattice between rows cells, mainly hepatocytes, epithelial cells responsible for the metabolism taking place in the liver. hand or foot), use of power injection, use of a vessel with multiple puncture attempts, and use of a peripheral IV that has been in place >24h can also increase the risk of extravasation [1315]. 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. 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. Greenway CV, Stark RD. No ductal dilation or masses. where n0 is the number of sectors connected to the source (n0= 6 here), Li^=Li/Lh the non-dimensional branch length, and n is the bifurcation level. Contrast flow and enhancement patterns seen on CTA can often be challenging and may often reveal more than is immediately apparent. 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. The physical components of a CTA include the CT scanner, intravenous cannula, access vein size, and power injector; the functional component is the patients cardiac status. When using bolus tracker technique, failure to adequately opacify the target vessels to reach the threshold needed for triggering the scan may also be an indication of decreased cardiac pump function. 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. Google Scholar, Schaverien MV, Evison D, McCulley SJ (2008) Management of large volume CT contrast medium extravasation injury: technical refinement and literature review. The hepatic veins drain the liver into the inferior vena cava. the contents by NLM or the National Institutes of Health. However these models, regardless their sophistication level14,15, are descriptive. 12), extra-cardiac shunts such as patent ductus arteriosus, bronchial artery, or coronary artery fistulas (Fig. Patient movement between localizer slice selection/ROI placement and the start of contrast administration/imaging can also affect ROI placement (i.e. Obstruction can be, Extrahepatic portal vein thrombosis Portal Vein Thrombosis Portal vein thrombosis causes portal hypertension and consequent gastrointestinal bleeding from varices, usually in the lower esophagus or stomach. Insights into Imaging At the smallest scale, the shape of the liver elemental systemsthe lobulesis discovered, while their permeability is also predicted. The total blood volume V is fixed, so is the mass flow rate of blood. No pleural or pericardial effusion. 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. In patients with small caliber access veins, a dual energy acquisition can be obtained. Evaluation of these graphs is important in identifying the planned flow rate and any changes to that. 5 is a good pattern. 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. They are reported to range from 500m up to 2.5mm in diameter for humans14,42,47. 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 portal venous system drains the intestines, pancreas, and spleen with numerous collateral anastomoses to other venous beds of the abdomen. In Eq. Alternatively, new access from the contralateral extremity vein can be obtained. (See also Overview of Vascular Disorders read more develop. Normal appendix. 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. It assumes that the bolus geometry of this initial injection and the final injection for the diagnostic scan would remain the same (Fig. 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. Transient interruption of contrast bolus results in suboptimal opacification of the pulmonary artery on initial contrast bolus, with subsequent diagnostic scan for pulmonary embolus after repeat injection using high pitch FLASH CTA. 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. 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]. Lower (4060KeV) monoenergetic reconstruction can be obtained to boost contrast opacification. When portal vein blood flow increases, hepatic artery flow decreases and vice versa (the hepatic arterial buffer response). Considering Darcy flow through the porous elemental system (i.e. California Privacy Statement, The diameter ratio of each tree has a unique value and obeys the Hess-Murrays law. Blood then enters the right ventricle across the tricuspid valve. Sketch of hexagonal (left side) and square configurations (right side). in cases of a pulmonary artery CTA, this implies delayed aortic opacification. If some contrast has gone into the patient, the study may still be salvageable. 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. Using contrast enhancement and flow patterns to identify the cause of a non-diagnostic CTA. Flashcards. Segmentation methods and processes begin with the acquisition of 3-D image data such as from a high resolution CT scan of a patient's lungs There is also reduced individual patient variability [8]. For a long time, such structures were considered as being the result of chance, i.e. Repeat injection using high pitch FLASH technique with free breathing (c) shows excellent opacification of the pulmonary artery. When a dual energy scanner is not available, we use a larger volume (1.5mL/kg) of contrast medium containing 350 mgI/mL iodine and use 80 or 100 kVp for image acquisition. Detailed examples can be found in Refs3436. It has been shown that 13% of these patients have mural thrombus in the extracardiac conduit [27], even without symptoms, which may be missed with suboptimal studies [27] Solutions for this are (1) Simultaneous upper and lower extremity (femoral vein/foot vein) injections at 45mL/s, so that both the SVC and IVC are opacified simultaneously [27]. Mixing artifacts can be seen in large aortic aneurysms and should not be confused with a thrombus (Fig. Imaging pearl: Techniques to overcome this artifact often rely on patient respiratory coaching, as the command take a breath in and hold it can lead some patients to take a rapid deep inspiratory breath, increasing the risk of transient attenuation of the contrast bolus. Considering any of the 3 networks, we note that each consists in a tree-shaped architecture delivering the blood through the connection of one inlet to an infinite number of outlets, the lobules (case of the hepatic artery and the portal vein), or from the lobules to one outlet in the case of the HV hepatic venous system. However, if the study is not salvageable or if no contrast went into the area of interest, the study will have to be repeated. Chaturvedi, A., Oppenheimer, D., Rajiah, P. et al. These are, however, not commonly seen in left atrium or left ventricle, and whenever seen should be considered abnormal (Fig. 15). When present, these findings should raise the suspicion of altered flow dynamics including underlying intra- or extra-cardiac shunt. The thinner channels form the canopy of the HA and PV trees and irrigate the lobules which behave like a porous system. 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. 7a and b). Insights Imaging 8, 127140 (2017). The sinusoids are A physiologically-based flow network model for hepatic drug elimination II: variable lattice lobule models. The work dealt with a surface with a round cross section. 3a), leak at the level of the hub (Fig. An electrical analogue of the entire human circulatory system. Rezania V, Marsh R, Coombe D, Tuszynski J. The architecture was based on bifurcation patterns. An official website of the United States government. Portal vein. The trusted provider of medical information since 1899, Overview of Vascular Disorders of the Liver, Last review/revision Jan 2022 | Modified Sep 2022. where K is the intrinsic permeability of the lobule. WebAnswer (1 of 1): The portal vein and hepatic artery provide blood flow to the liver. Calculations of the diameter ratio, length ratio and splitting number of branches, data from Debbaut et al.19,29 and Ma et al.22. Proc Staff Meet Mayo Clin 31(9):281287, CAS This prompted initiation of cardiopulmonary resuscitation and calling the code team. This should be reviewed by the radiologist. kycurrier. this patient does have hepatic steatosis and a tiny gallstone or cholesterol polyp. Causes include infection, arteriosclerosis, trauma, and vasculitis. Lucia U, Grisolia G. Time: a constructal viewpoint & its consequences. Hepatic vein disorders can result in focal or diffuse venous obstruction. Lee J, Kim S, Lorente S, Bejan A. Vascularization with trees matched canopy to canopy: Diagonal channels with multiple sizes. J Thorac Imaging 31(1):5662, Coulier B, Van den Broeck S (2013) A case of massive transient reduction of attenuation of iodine contrast bolus during computed tomography pulmonary angiography: why and how to avoid it. Measuring read more , blood-filled cystic spaces develop in the sinusoids (microvascular anastomoses between the portal and hepatic veins). The data are from Refs16,21,28. No urolithiasis or hydronephrosis. 5b). 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. cannula mismatch the pressure may exceed the threshold, which may limit the flow rate. Visceral arteries are patent. Non-target vessel opacification may hold key to underlying pathophysiology. The sector covered has an angle of /6 from the central vein, see Fig. Also note the differential enhancement in descending aorta. The narrowing of the left subclavian vein prevented adequate opacification of the pulmonary artery. 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. 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. Their complexity often forces to reduce the hydrodynamic studies of the liver to its morphofunctional unit, the lobule23,24. Privacy 4 would be to use squared shaped lobules of side LS with AS=LS2. The Physics of Life: The Evolution of Everything. Axial CECT (a) shows a type B dissection with mixing of contrast in the true lumen (arrow). Decreased systolic function of left ventricle can result in dependent contrast pooling and layering in the aorta [25]. EXAMPLE REPORTING TEMPLATE WITH CHECKLIST: LOWER CHEST: Lung bases are clear. J Am Soc Echocardiogr: Off Publ Am Soc Echocardiogr 23(7):685713, quiz 786-688, Article The result is a systemic to pulmonary artery shunt. At such a small scale, it seems appropriate to use a porous medium analogy16,4143. WebLiver Vasculature. For the sake of simplicity, assume that the hepatic artery and the portal vein are one single conduct of diameter d and length Ld, through which the mass flow rate is hence 3mh/6. It is important to identify this before the injection is initiated as a mismatch can lead to either power injector induced reduction in flow rate of the injection due to peak pressure being reached (Fig.

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