Hemihepatic versus total hepatic inflow occlusion during hepatectomy: a systematic review and meta-analysis

AIM:To evaluate the clinical outcomes of patients undergoing hepatectomy with hemihepatic vascular occlusion(HHO) compared with total hepatic inflow occlusion(THO).METHODS:Randomized controlled trials(RCTs) comparing hemihepatic vascular occlusion and total hepatic inflow occlusion were included by a systematic literature search.Two authors independently assessed the trials for inclusion and extracted the data.A metaanalysis was conducted to estimate blood loss,transfusion requirement,and liver injury based...     

A technique for safely teaching major hepatectomy to surgical residents

In this era of combination chemotherapy and biologic treatment, the ability to downsize tumors that were previously unresectable will increase the need for major hepatic resections. This makes teaching consistent surgical approaches to these difficult cases imperative. Herein we outline a standardized surgical approach to right hepatectomy, which allows the procedure to be divided into a series of well-defined technical maneuvers. Preoperative preparation and communication with anesthesia to ensure a low central venous pressure is emphasized. A right hepatectomy is described by dividing the procedure into 5 steps: (1) initial mobilization and intraoperative ultrasound, (2) cholecystectomy and extrahepatic inflow occlusion and, (3) posterior mobilization and extrahepatic venous outflow ligation, (4) parenchymal transection, and (5) hemostasis and closure. Such techniques, once adopted by the surgeon, will allow for controlled parenchymal transection, minimal need for inflow occlusion to the liver remnant, and safe and efficient hepatectomy.     

PCA技术在颅内血管成像中的临床应用

目的扩大相位对比血管成像(PCA)技术在颅内血管成像中的临床应用,并与流人(Inflow)技术比较。方法46例颅内血管异常患(男34例,女12例,年龄3～60岁,平均年龄41．3岁)于临床症状出现后均经PCA与Inflow两种方法检查。本研究全部MR成像均采用PHILIPS GYROSCAN NT 1．0磁共振超导扫描机进行。两种成像方法的后处理均采用MIP重建。结果在46例颅内血管异常患中,PCA测出动静脉畸形20例,动脉瘤15例,海绵状血管瘤6例,单纯静脉瘤1例,以及静脉窦栓塞2例,只有2例海绵状血管瘤未测出,而Inflow相应地测出动静脉畸形18例,动脉瘤15例,海绵状血管瘤8例但静脉系血管畸形未测出1例。PCA与Infolw的检出率分别为95．6％(44／46)和86．9％(40／46)。结论虽然Inflow显示颅内血管异常与PCA有些相似,但它未能显示静脉系血管异常。相比之下,PCA能显示各种颅内血管异常,值得临床广泛应用。     

高原鼠第一肝门持续阻断的安全时限

目的：探讨高原鼠第一肝门持续阻断的安全时限。方法：SD大鼠分为假手术组、高原实验组及低海拔对照组。实验组及低海拔对照组均分为持续阻断15分钟、30分钟、60分钟、90分钟及120分钟组。无菌条件下用无创血管夹阻断肝十二指肠韧带,造成包括尾叶在内的全部肝实质缺血,再灌注1h、3h、6h及24h后处死存活鼠,测定血清AST及GSH-ST的活性,并进行病理观察。结果：高原鼠第一肝门持续阻断60分钟以下无实验动物死亡,病理改变为可逆性的,持续阻断90分钟及120分钟组实验动物存活率明显降低,病理改变为不可逆性。血清AST及GSH-ST活性亦明显较持续阻断60分钟及以下各组为高,明显短于低海拔对照组的90分钟。结论：高原鼠第一肝门持续阻断的安全时限较低海拔地区为短。     

Current status of computational fluid dynamics for cerebral aneurysms: The clinician’s perspective

The ultimate management goal for unruptured intracranial aneurysms is to select the aneurysms at risk of rupture and treat them. Computational fluid dynamics (CFD) utilizes mechanical engineering principles to explicate what occurs in tubes (vessels) and bulges (aneurysms). CFD parameters have been related to the biological processes that occur in the aneurysm wall, and models have been developed to predict the risk of aneurysm rupture. A PubMed search from 1 January 1970 to 30 November 2010 was carried out using the keywords “computational fluid dynamics” AND “cerebral aneurysm”. References were also reviewed for relevant articles. All relevant articles were then reviewed by a vascular neurosurgeon, who found that the hemodynamic parameters of wall shear stress (WSS), WSS gradient, inflow jet, impingement zone, and aneurysm inflow-angle (IA) lack the predictive values required for clinical practice. CFD study can now be simulated and reproduced in a simple and fast analysis of steady, non-pulsatile flow with phase contrast magnetic resonance-derived volumetric inflow rate but the key question of whether a patient-specific CFD model can predict the rupture risk of unruptured intracranial aneurysms remains to be determined in future studies incorporating multivariate analysis. CFD models will become available for routine clinical practice as the computational power of computers further improves.     

3.0T MR反转时间对流入反转恢复序列门静脉成像质量的影响

目的 探讨3.0T MR 反转时间（TI）对流入反转恢复序列（IFIR）门静脉系统非对比增强图像质量的影响。方法 对健康志愿者 31名（正常组）、门静脉高压患者12例（门静脉高压组）采用不同的TI行冠状位IFIR序列扫描。评估采用不同TI所得的IFIR图像的门静脉主干SNR、主动脉SNR、肝脏组织SNR、门静脉主干CNR,根据门静脉及其分支显示清晰程度进行评分。对上述指标的比较采用单因素方差分析或配对t检验。结果 两组受检者不同TI图像的门静脉主干SNR和CNR差异均无统计学意义（P均>0.05）。正常组肝脏组织SNR、主动脉SNR差异有统计学意义（P均<0.05）,不同TI门静脉图像分支评分差异无统计学意义（P>0.05）。门静脉高压组不同TI图像的肝内分支评分构成比差异有统计学意义（P=0.012）;选择900 ms TI时,门静脉高压组门静脉主干SNR和CNR、图像评分均低于正常组,TI为1100 ms时,两组图像评分的差异无统计学意义（P>0.05）。结论 对于正常受检者,TI为700 ms时既能得到较好的背景压制的图像,又能保证显示门静脉远端细支血管;而对于门静脉高压患者,选择TI为1100 ms更有利于门静脉分支血管的显示。     

Validation of the coupling of magnetic resonance imaging velocity measurements with computational fluid dynamics in a U bend

Magnetic resonance imaging (MRI) can be used in vivo in combination with computational fluid dynamics (CFD) to derive velocity profiles in space and time and accordingly, pressure drop and wall shear stress distribution in natural or artificial vessel segments. These hemodynamic data are difficult or impossible to acquire directly in vivo. Therefore, research has been performed combining MRI and CFD for flow simulations in flow phantoms, such as bends or anastomoses, and even in human vessels such as the aorta, the carotid, and the abdominal bifurcation. There is, however, no unanimity concerning the use of MRI velocity measurements as input for the inflow boundary condition of a CFD simulation. In this study, different input possibilities for the inflow boundary conditions are compared. MRI measurements of steady and pulsatile flow were performed on a U bend phantom, representing the aorta geometry. PAMFLOW (ESI Software, Krimpen aan den Ussel, The Netherlands), an industrial CFD software package, was used to solve the Navier-Stokes equations for incompressible flow. Three main parameters were found to influence the choice of an inflow boundary condition type. First, the flow rate through a vessel should be exact, since it proves to be a determining factor for the accuracy of the velocity profile. The other decisive parameters are the physiology of the flow profile and the required computer processing unit time. Our comparative study indicates that the best way to handle an inflow boundary condition is to use the velocities measured by MRI at the inflow plane as being fixed velocities. However, before using these MRI velocity data, they first should be corrected for the partial volume effect by filtering and second scaled in order to obtain the correct flow rate. This implies that a reliable flow rate measurement absolutely is needed for CFD calculations based on MRI velocity measurements.     

Covert muscle excitation is outflow from the central generation of motor imagery

Two studies were conducted in an attempt to examine inflow and outflow processing by examining covert muscle excitation during motor imagery (MI) and its correlation with motor task performance. Examining 80 novice dart throwers in Experiment 1, MI produced greater levels of covert excitation at the dominant biceps in comparison to control imagery (CI). In addition, covert excitation correlated significantly with imagery ability and imagery vividness. This excitation, however, did not predict motor task acquisition or retention. Experiment 2 attempted to manipulate pre-imagery relaxation states by giving 104 novice dart performers a relaxation task or a distraction task before imagery sessions. MI resulted in improved task retention and resulted in significantly greater covert muscle excitation at the frontalis in comparison to CI. The relaxation condition, however, did not yield greater levels of muscular relaxation in comparison to the distraction condition, and did not yield greater imagery vividness or motor performance. Finally, covert muscle excitation did not predict motor acquisition or retention error. Results suggest that covert excitation is a byproduct of the central generation of the image that does not relate meaningfully to motor skill acquisition or retention gains.     

3.0T MR流入反转恢复序列门静脉成像及影响成像质量的技术因素

目的 探讨3.0T MR流入反转恢复(IFIR)序列对门静脉系统进行非对比增强成像的可行性及影响成像质量的技术因素。 方法 采用GE Signa HDx 3.0T MR扫描仪对240例患者行冠状位IFIR序列扫描。在GE AW4.4工作站行三维MIP重建,对门静脉各级分支显示程度及清晰度进行评分,并与呼吸频率及呼吸节律、反转时间(TI)等因素进行对比,分析影响成像质量的技术因素。 结果 门静脉显示情况(TI 900 ms):5分32例,4分62例,3分64例,2分20例,1分27例,0分35例;高分组(3~5分)158例(158/240,65.83%),低分组(0~2分)82例(82/240,34.17%);图像质量评分受设备序列(包括IFIR序列本身不稳定因素、预饱和带放置位置)及患者个体因素(包括呼吸因素、TI)的影响。 结论 3.0T MR IFIR冠状位血管成像序列可用于显示门静脉系统。