China
Africa
Explore chapters and articles related to this topic
Liver and biliary system, pancreas and spleen
Published in A Stewart Whitley, Jan Dodgeon, Angela Meadows, Jane Cullingworth, Ken Holmes, Marcus Jackson, Graham Hoadley, Randeep Kumar Kulshrestha, Clark’s Procedures in Diagnostic Imaging: A System-Based Approach, 2020
A Stewart Whitley, Jan Dodgeon, Angela Meadows, Jane Cullingworth, Ken Holmes, Marcus Jackson, Graham Hoadley, Randeep Kumar Kulshrestha
It is advisable to scan the pancreas at the beginning of the examination, before bowel gas rises and obscures the pancreas and epigastric region. With the patient in a supine position on the couch, a curvilinear array of 2.5–5 MHz is placed in the midline at the level of the xiphisternum (Fig. 6.23a). Often there needs to be a slight caudal angle to obtain good views of the pancreas, using the left lobe of liver as an acoustic window. The pancreas is located superior to the splenic vein and is located using the landmarks of the splenic vein and superior mesenteric artery (Fig. 6.23b). Often the head and body of pancreas can be seen more easily than the tail (Fig. 6.23c). It may be necessary to angle the probe slightly to the left to see the pancreatic tail.
Imaging of the genitourinary tract
Published in Sarah McWilliams, Practical Radiological Anatomy, 2011
o The left renal vein crosses the midline to join the inferior vena cava (IVC) underneath the superior mesenteric artery (SMA). The third part of the duodenum and the left renal vein are found between the SMA and the aorta; a further variant is a retroaortic left renal vein.
Hemodynamic analysis of hybrid treatment for thoracoabdominal aortic aneurysm based on Newtonian and non-Newtonian models in a patient-specific model
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2023
Jun Wen, Jiarong Wang, Liqing Peng, Ding Yuan, Tinghui Zheng
As shown in Figure 1a, the inflow site for visceral bypass was at distal AA. In addition, visceral and renal arteries were ligated at the origin to avoid back-flow in the aneurysm and the risk of type II endoleak. Four-bifurcated visceral grafts, respectively connected to the right renal artery (RRA), superior mesenteric artery (SMA), celiac artery (CA), and left renal artery (LRA) were marked in Figure 1b. The geometrical features of the patient-specific RVR including the diameters of proximal TA, distal AA, LCIA and RCIA are approximately 32, 17.5, 7.5, and 7.8 mm, respectively. In addition, the diameters of the main trunk and branch grafts (CA, SMA, LRA, and RRA) of the visceral bypass are approximately 15.4, 5.8, 5.4, 3.2, and 4.2 mm, respectively. Moreover, the anastomotic angle between the AA and the main trunk of bypass grafts is approximately 62°. Based on a 20-day postoperative ultrasound follow-up report of this patient, atherosclerotic plaques can be observed in the infrarenal AA region (region A), as shown in Figure 1d, where the plaques were marked with blue oval, while there were no atherosclerotic plaques reported in the anastomosis region (region B).
A modified method of computed fluid dynamics simulation in abdominal aorta and visceral arteries
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2021
Yun Shi, Chen Peng, Junzhen Liu, Hongzhi Lan, Chong Li, Wang Qin, Tong Yuan, Yuanqing Kan, Shengzhang Wang, Weiguo Fu
Les et al. reconstructed patient-specific AAA models including the visceral arteries, and measured the flow rates of supra-celiac (SC) and IR aorta by 2D PCMRI. The difference of flow rates between SC and IR aorta was assigned to the celiac artery (CA), superior mesenteric artery (SMA) and bilateral renal arteries (RA) according to the percentage from literature (Suh et al. 2011). However, the flow rates assigned to visceral arteries were unlikely accurate since they were not measured values. To overcome this defect, we measured the flow rates of not only SC and IR aorta but also CA, SMA, bilateral RAs for a volunteer by 2D PCMRI. The imaging planes of 2D PCMRI were roughly the ends of SC aorta, IR aorta, CA, SMA and bilateral RAs of the patient-specific 3D geometric model (Figure 1a). The flow BC was imposed on the inlet of SC aorta and the outlets of visceral arteries, the RCR BC was imposed on the outlet of IR aorta to run the CFD simulation (Figure 1b), which will be detailed in Section 2.3.
Influence of renal artery stenosis morphology on hemodynamics
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2021
Zhuxiang Xiong, Ding Yuan, Jiarong Wang, Tinghui Zheng, Yubo Fan
To ensure that the blood flow fully developed in the tube, the inlet (upper abdominal aorta) and outlets (other branch arteries, including superior mesenteric artery, celiac trunk artery, renal arteries and iliac arteries) were extruded ten times the diameter. A time-dependent pulsatile waveform of flow rate was set as the inlet boundary condition for all models (Figure 1f). At the outlets, three-element Windkessel models (3-EWM) (Figure 1g) were coupled to approximate the resistance and compliance of the downstream vascular beds (Les et al. 2010). The proximal resistance (R1), distal resistance (R2), and compliance (C) were calculated to match normal physiological blood pressure (120/80 mmHg, systole, and diastole, respectively) in the ideal normal model (Marrocco-Trischitta et al. 2018). These parameters would be applied in all ideal models. In addition, the arterial walls were assumed to be no-slip and rigid (Boyd et al. 2016).