0D-1D coupling model and 3D fluid-structure interaction model based on coronary CT angiography for displaying hemodynamic characteristics of coronary artery stenosis

Objective To observe value of 0D-1D coupling model and 3D fluid-structure interaction(FSI)model based on coronary CT angiography(CCTA)for displaying hemodynamic characteristics of coronary artery stenosis.Methods Based on CCTA data of the stenosed left anterior descending branch(LAD)in a patient with coronary heart disease,an 0D-1D coupling model and 3D FSI model were built,respectively.Then hemodynamic characteristic indexes,including the pressure,flow velocity and wall shear stress(WSS)were obtained in every 0.01 s during 1 s at 5 sampling points(i.e.sampling point 1—5)using these 2 models,respectively,and the consistencies of the results between models were evaluated with Spearman correlation coefficient r s.Results The time consuming for construction of 0D-1D coupling model and 3D FSI model was 0.033 min and 704 min,respectively.Both models showed basically distribution of the pressure,flow velocity and WSS of the stenosed LAD.For more details,the pressure at the stenosed segment of LAD and the proximal segment of stenosis were both higher,which gradually decreased at the distal segment of stenosis,and the flow velocity at the proximal segment of stenosis was in a relatively slow and uniform condition,with significantly increased flow velocity and WSS at the stenosed segment.Compared with 3D FSI model,0D-1D vascular coupling model was relatively unrefined and lack of distal flow lines when displaying blood flow velocity.For sampling point 2 at the stenosed segment of LAD,no significant consistency for pressure between 2 models was found(P=0.118),but strong consistency for the flow velocity and WSS(r s=0.730,0.807,both P<0.05).The consistencies of pressure,flow velocity and WSS between 2 models at the proximal and distal segment of stenosis,i.e.1,3—5 sampling points were week to moderate(r s=0.237—0.669,all P<0.05).Conclusion 0D-1D coupling model exhibited outstanding computational efficiency and might provide relatively reasonable results,while 3D FSI model showed higher accuracy for details and streamline when simulating LAD stenosis.

十二指肠外压性病变的影像学诊断

十二指肠外压性病变在日常影像检查中较少见。本文收集2010～2012年12月间经影像学检查和临床病理证实的23例十二指肠外压性病变作回顾性分析，以期提高对其认识和诊断水平。

CEUS: A new imaging approach for postoperative vascular complications after right-lobe LDLT

AIM: To investigate contrast-enhanced ultrasound (CEUS) for early diagnosis of postoperative vascular complications after right-lobe living donor liver transplantation (RLDLT). METHODS: The ultrasonography results of 172 patients who underwent RLDLT in West China Hospital, Sichuan University from January 2005 to June 2008 were analyzed retrospectively. Among these 172 patients, 16 patients' hepatic artery flow and two patients' portal vein flow was not observed by Doppler ultrasound, and 10 patients' bridging vein flow was not shown by Doppler ultrasound and there was a regional inhomogeneous echo in the liver parenchyma upon 2D ultrasound. Thus, CEUS examination was performed in these 28 patients. RESULTS: Among the 16 patients without hepatic artery flow at Doppler ultrasound, CEUS showed nine cases of slender hepatic artery, six of hepatic arterial thrombosis that was confirmed by digital subtraction angiography and/or surgery, and one of hepatic arterial occlusion with formation of lateral branches. Among the two patients without portal vein flow at Doppler ultrasound, CEUS showed one case of hematoma compression and one of portal vein thrombosis,and both were confirmed by surgery. Among the 10 patients without bridging vein flow and with liver parenchyma inhomogeneous echo, CEUS showed regionally poor perfusion in the inhomogeneous area, two of which were confirmed by enhanced computed tomography (CT), but no more additional information about bridging vein flow was provided by enhanced CT. CONCLUSION: CEUS may be a new approach for early diagnosis of postoperative vascular complications after RLDLT, and it can be performed at the bedside.

Transient small bowel angioedema due to intravenous iodinated contrast media

Three cases of transient proximal small bowel angioedema induced by intravenous administration of nonionic iodinated contrast media (CM) are presented.Computed tomography (CT) images in the venous phase displayed the proximal small bowel with circumferential thickening of the wall including the duodenum and proximal segment of the jejunum.The bowel wall was normal in non-enhanced images,and normal or inconspicuous in arterial phase enhanced images.In one of the three cases,the bowel wall was thickened in venous phase but disappeared in the 40 s delayed phase images.No filling defect was seen in the lumen of the superior mesenteric artery and vein.No peritoneal effusion or mesentery abnormality was found.Each of these patients reported only mild abdominal discomfort and recovered without specific treatment within a short time.Only one patient suffered mild diarrhea after scanning which had resolved by the following day.The transient anaphylactic small bowel angioedema due to intravenous iodinated contrast media was easily diagnosed based on its characteristic CT findings and clinical symptoms.Differential diagnosis may include inflammatory and ischemic bowel disease,as well as neoplasms.A three-phase CT protocol and good under-standing of this disorder are fundamentally important in the diagnosis of this condition.The supposed etiology behind the transient anaphylactic reaction to intravenous administration of iodinated CM in small bowel is similar to other CM-induced hypersensitive immediate reactions.The predilection location of transient anaphylactic bowel angioedema is the small intestine,particularly the proximal segment.A speculated cause may be the richer supply of vessels in the small intestine,ample mucous folds and loose connective tissue in the duodenum and the jejunum.

NSAIDs for prevention of pancreatitis after endoscopic retrograde cholangiopancreatography:Ready for prime time?

Acute pancreatitis is the most common and the most fearful complication of endoscopic retrograde cholangiopancreatography (ERCP).Prevention of post-ERCP pancreatitis has therefore been of great interest to endoscopists performing ERCP procedures.So far,only pancreatic duct stenting during ERCP and rectal administration of a non-steroidal anti-inflammatory drug (NSAID) prior to or immediately after ERCP have been consistently shown to be effective for prevention of post-ERCP pancreatitis.This commentary focuses on a short discussion about the rates,mechanisms,and risk factors for post-ERCP pancreatitis,and effective means for its prevention with emphasis on the use of NSAIDs including a recent clinical trial published in The New England Journal of Medicine by Elmunzer et al.

Diagnosis of carotid body tumor by digital subtraction angiography

Objective: To make a further understanding of the features of the carotid body tumor (CBT) by digital subtraction angiography (DSA) so as to explore the clinical value of DSA diagnosis and interventional therapy for CBT. Methods: DSA data from 12 cases of CBT were analyzed retrospectively. A consensus interpretation of the DSA appearances in all of the patients was reached after dynamic observation by 2 experienced radiologists in a double blind manner. Results: Definite diagnosis in all cases could be made by DSA. The DSA features of the CBT included bigger bifurcation angles of the internal and external carotid arteries, displacement of internal and external carotid arteries, CBT supplied by external carotid arteries in most cases and the significant increase of tumor blood vessels in bifurcation. Invasion of internal or external carotid arteries was found in 6 cases. Smaller stained area of the tumor and significantly reduced intraoperative bleeding were found after embolization of the supplying arteria in 2 cases. Conclusion: DSA is the effective method for the diagnosis and preoperative assessment of CBT. Preoperative embolization of CBT may contribute to the reduced intraoperative bleeding.

IMAGE RECONSTRUCTION AND OBJECT CLASSIFICATION IN CT IMAGING SYSTEM

By obtaining a feasible filter function,reconstructed images can be got with linear interpolation and liftered backprojection techniques.Considering the gray and spstial correlation neighbour informations of each pixel,a new supervised classification method is put forward for the reconstructed images,and an experiment with noise image is done,the result shows that the method is feasible and accurate compared with ideal phantoms.

Computerized tomography pleurography: a new method for detecting minor pleural lesion

Objectives To evaluate the ability of CT pleurography (CTP) in detecting minor pleural lesions in patients with pleural effusion and to assess its value in distinguishing malignant from benign pleural lesions. Methods A prospective study of 50 patients with pleural effusion was conducted using conventional CT and CTP. CT scan was run after injecting an appropriate amount of contrast medium into the pleural cavity. Results In 24 patients, all lesions detected by conventional CT were demonstrated by CTP. In 13 of 24 patients, CT pleurography detected additional lesions. In 20 of 26 patients with negative findings on conventional CT, CTP was capable of demonstrating the presence of pleural lesions. The sensitivity, specificity and accuracy of detecting pleural lesions were 25%, 100% and 30% for conventional CT, 86%, 100% and 87% for CTP, respectively. Conclusion CTP is superior to conventional CT in detecting and for the differential diagnosis benign and malignant pleural lesions.