No urolithiasis or hydronephrosis. This is similar to contrast attenuation in SVC. Landes, G. Einige Untersuchungen an elektrischen Analogieschaltungen zum Kreislaufsystem. Its role is fundamentally important, particularly in the transformation of toxic substances to elements that the body can eliminated. 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. By using this website, you agree to our In Eq. Imaging pearl: Check the access vein and access cannula before initiating contrast injection. The splitting number is calculated from the ratio of the number of daughter branches and mother branches. Use of delayed images after 30s can help differentiate soft plaque/thrombus from slow flow when dependent pooling is seen. 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. large respiratory effort, cardiac motion, and/or the patient physically shifting on the table), leading to premature, delayed or even no bolus triggering. 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. 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. 2023 BioMed Central Ltd unless otherwise stated. Repeat injection with placement of ROI in true lumen resulted in adequate evaluation of dissection. In type B dissection, identification of false lumen thrombus can be overestimated by first pass CTA/MRA. Alalaimi M, Lorente S, Wechsatol W, Bejan A. (See also Overview of Vascular Disorders of the Liver.) The entire volume of the lobules is fixed because the blood volume is fixed. The architecture was based on bifurcation patterns. In addition to target vessel opacification, evaluation of non-target vessels may also contain important clues to the underlying disease that brought the patient to the ED. Differential enhancement of pulmonary arteries during a pulmonary artery CTA can be seen in patients with Fontan circulation (Fig. Google Scholar, Litmanovich D, Bankier AA, Cantin L, Raptopoulos V, Boiselle PM (2009) CT and MRI in diseases of the aorta. The liver is one of the most important organ of the human body. 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. Learn more about the Merck Manuals and our commitment to Global Medical Knowledge. Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. 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. Virtual tissues in toxicology. Br J Radiol 84(999):197203, Article and transmitted securely. (AVI 5728 kb). There may be more than one type of CT scanner within the same hospital system. Necrosis 10). 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 . The physiological principle of minimum work: I. In addition, there are some life-threatening findings, which unless sought for, may remain hidden in plain sight. In patients with pulmonary hypertension or congestive heart failure (CHF), pulmonary circulation can be slow and PTT will be prolonged, which may lead to delayed contrast arrival in the non target vessel, e.g. 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 . We consider that Ah=AS, which means that the hexagon is reshaped to become a square, and LS=33/42Lh1.6Lh. 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. Through the following text, we will address the important pieces of this fine-tuned sequence and how malfunction of any individual component can limit attempts to obtain a diagnostic study. Sagittal CECT MIP image demonstrates differential opacification of the aorta proximal and distal to the aortic coarctation with post-stenotic dilatation. Rezania V, Marsh R, Coombe D, Tuszynski J. (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. 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. 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. There is progressively increasing use of CT scans in the emergency department (ED) in recent years [1]. Diffuse ischemia can cause ischemic hepatitis Ischemic Hepatitis Ischemic hepatitis is diffuse liver damage due to an inadequate blood or oxygen supply. Patient movement between localizer slice selection/ROI placement and the start of contrast administration/imaging can also affect ROI placement (i.e. Unless sagittal images are also reviewed, this subtle sign may be the only significant clue seen on axial CTA images. An optimal, diagnostic thoracic CTA study is never obtained by accident. 3b) with abrupt cessation of flow, or contrast medium extravasation. WebIntrahepatic congenital PSSs occur predominantly in large-breed dogs and are often attributable to a patent ductus venosus, originating from the intrahepatic left division of the portal vein and connecting to the left hepatic vein. A delayed phase, 40s acquisition can help in identifying any thrombus, vegetation, or fibrin sheath attached to the catheter. The modular microarchitecture of human liver. Extravasation of contrast material, in which contrast medium is injected outside the intended vessel, is an infrequent, but well known complicationof CTA (Fig. This is important since there is a higher risk of pulmonary thromboembolism (319%) in these patients [27]. For example, contrast enhancement of a distal chamber before adequate opacification of a proximal vessel/chamber is never normal. The lobules area porous medium located between the tree canopies. Doppler Ultrasound of the Mesenteric Vasculature The data are from Refs16,21,28. 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]. 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. Lee J, Kim S, Lorente S, Bejan A. Vascularization with trees matched canopy to canopy: Diagonal channels with multiple sizes. PubMed Overview of Vascular Disorders of the Liver - Hepatic and 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. No body wall masses. Inferior Vena Cava: Anatomy, Function, and Significance - Verywell In addition, attempts to remove the extravasated contrast via aspiration have not been shown to be consistently beneficial. At such a small scale, it seems appropriate to use a porous medium analogy16,4143. Understanding these graphs will help the radiologist plan a repeat contrast injection to overcome the deficiencies of the first injection and thus obtain a diagnostic scan. Power injector pressure-time and flow rate-time graphs in a different patient with IV infiltration during the injection (b) shows rapid drop in pressure and cessation of flow at the time of contrast extravasation. Regardless of the post-extravasation treatment method, patients should be evaluated by the radiologist. Acute pancreatitis is inflammation that resolves both clinically and histologically. Copyright 2023 Merck & Co., Inc., Rahway, NJ, USA and its affiliates. 7c). The CT technician subsequently called the radiologist to check the images and ask for a repeat injection after identifying abnormal contrast enhancement. Thoracic outlet syndrome (TOS) refers to the effects of dynamic compression of the nerve, artery, and/or vein as these structures cross the thoracic outlet due to changes in arm position, typically induced by elevation of the arms [16]. Bonfiglio A, Leungchavaphongse K, Repetto R, Siggers JH. Understanding the way its blood vasculature works is key. The authors declare no competing interests. The blood flow path is represented by the arrows. 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. This is called the transit delay (Table 2) and varies from patient to patient and scanner to scanner. 8a and b). There is insufficient opacification of the pulmonary circulation due to siphoning of contrast by ECMO. 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. Normal hepatic anatomy occurs in approximately 80% of cases, for the remaining 20% multiple variations have been described. Contrast-blood mixing artifacts are often seen in the right atrium, right ventricle and pulmonary artery during a pulmonary artery CTA due to unopacified blood returning from the IVC. Describing the lobules under the assumption of slices of highly vascularized hexagons represents a commonly admitted hypothesis. The sinusoids tortuous network bathes the entire lobule, supplying the blood to the central vein from the 6 sources (hepatic artery+portal vein). Iliac Artery This is consistent with the results provided by Siggers et al.40 whose finite elements modeling in 2D indicates a reduction in blood flow rate in a square lattice as opposed to a hexagonal one. Debbaut et al.19,29 explained that they could not measure the total number of branches when the splitting level increases. Blood then enters the right ventricle across the tricuspid valve. Murray CD. Cardiomyopathy resulting in poor contrast opacification of the left atrium, left ventricle and aorta on a thoracic CTA being obtained to evaluate for pulmonary embolism on a 64 slice CT. CECT demonstrates excellent opacification of the right heart, but poor opacification in the left heart related to prolonged pulmonary circulation time in a patient with left ventricular systolic dysfunction. They are reported to range from 500m up to 2.5mm in diameter for humans14,42,47. Fontan shunt is performed as the third stage of ventricular repair and involves anastomosis between the IVC and the left pulmonary artery. Liver Vasculature Cirrhosis is characterized by regenerative nodules surrounded by dense read more is the most common cause of diffuse intrahepatic venous outflow obstruction. Use OR to account for alternate terms 5. Imaging Pearl: Manufacturer recommendations for the central venous catheter that is being used should be adhered to for peak flow rate. At the smallest scale, the shape of the liver elemental systemsthe lobulesis discovered, while their permeability is also predicted. WebThe hepatic artery (which is oxygen-rich) supplies the rest. 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. In addition, there are some life-threatening findings, which unless sought for, may remain hidden in plain sight. However these models, regardless their sophistication level14,15, are descriptive. 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. 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. WebThe hepatic circulation is highly sensitive to changes in circulating blood volume and serves as a major buffer for expanded or contracted blood volume. Normal appendix. However, the contrast injection is typically performed slower than peripheral routes due to safety concerns. 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. 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. When present, these findings should raise the suspicion of altered flow dynamics including underlying intra- or extra-cardiac shunt. Referred to as the abdominal-thoracic pump, initial deep inspiration decreases intrathoracic pressure and increases intraabdominal pressure, acutely increasing venous return, favoring flow from the IVC over the superior vena cava (SVC), resulting in a bolus of nonopacified blood entering the right heart from the abdomen [19, 20]. The hepatic veins (there are three) carry blood out of the liver and empty into the vena cava. Normal caliber small and large bowel. Bhattacharya S, Shoda LKM, Zhang Q, Woods CG, Howell BA, Siler SQ, Woodhead JL, Yang Y, McMullen P, Watkins PB, Andersen M. E modeling drug- and chemical-induced hepatotoxicity with systems biology approaches. Human error is a common source of inappropriate placement. Decreased systolic function of left ventricle can result in dependent contrast pooling and layering in the aorta [25]. Diffuse obstruction results in congestion of the sinusoids, hepatomegaly, portal hypertension Portal Hypertension Portal hypertension is elevated pressure in the portal vein. 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. Both sources of blood mix in the sinusoids. Careers, Unable to load your collection due to an error. The objective of this work is to lay the theoretical foundations of the deterministic behavior of the human liver vasculature, as a hierarchical fluid mechanics system. Power injector is used to inject contrast medium and saline chaser at a constant flow rate for the entire duration of the injection. Non-target vessel opacification may hold key to underlying pathophysiology. J Thorac Cardiovasc Surg 145(3 Suppl):S208S212, Lee S, Chaturvedi A (2014) Imaging adults on extracorporeal membrane oxygenation (ECMO). Numerical modeling of oxygen availability in the AMC bioartificial liver. Evaluating the time attenuation curves generated by either of these techniques is important to understand normal and abnormal contrast arrival and pulmonary transit time. government site. The fluid enters a mother tube (diameter di and length Li) and splits through n daughter tubes of constant geometrical features (diameter di+1 and length Li+1). 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 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. 17af) of aorta, poor opacification of cardiac chambers, and suboptimal enhancement of the pulmonary vessels. Debbaut C, et al. reports a lobule permeability of 4.8 109 m2. Contrast arrival in the target vessel can be determined by using test bolus or bolus tracker technique [7, 8]. This artifact should be considered when there is decreased opacification of multiple bilateral pulmonary arteries at the same level without vessel lumen distention: true pulmonary emboli typically present at various levels and normally expand the vessel lumen acutely [19]. Blood is then pushed out when reaching the center of the lobule through the central vein parallel to the portal triad. PTT can be calculated by evaluating the time attenuation graph obtained from the test bolus (Fig. Building a 3D virtual liver: methods for simulating blood flow and hepatic clearance on 3D structures. https://doi.org/10.1007/s13244-016-0524-3, DOI: https://doi.org/10.1007/s13244-016-0524-3. 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. The latter led to the duct length ratio. Liver Exam #2. Systems modeling of developmental vascular toxicity. 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.
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