Hepatic Arterial System Research Articles

K-t GRAPPA-accelerated 4D flow MRI of liver hemodynamics: influence of different acceleration factors on qualitative and quantitative assessment of blood flow.

We sought to evaluate the feasibility of k-t parallel imaging for accelerated 4D flow MRI in the hepatic vascular system by investigating the impact of different acceleration factors. k-t GRAPPA accelerated 4D flow MRI of the liver vasculature was evaluated in 16 healthy volunteers at 3T with acceleration factors R = 3, R = 5, and R = 8 (2.0 × 2.5 × 2.4 mm(3), TR = 82 ms), and R = 5 (TR = 41 ms); GRAPPA R = 2 was used as the reference standard. Qualitative flow analysis included grading of 3D streamlines and time-resolved particle traces. Quantitative evaluation assessed velocities, net flow, and wall shear stress (WSS). Significant scan time savings were realized for all acceleration factors compared to standard GRAPPA R = 2 (21-71 %) (p < 0.001). Quantification of velocities and net flow offered similar results between k-t GRAPPA R = 3 and R = 5 compared to standard GRAPPA R = 2. Significantly increased leakage artifacts and noise were seen between standard GRAPPA R = 2 and k-t GRAPPA R = 8 (p < 0.001) with significant underestimation of peak velocities and WSS of up to 31 % in the hepatic arterial system (p <0.05). WSS was significantly underestimated up to 13 % in all vessels of the portal venous system for k-t GRAPPA R = 5, while significantly higher values were observed for the same acceleration with higher temporal resolution in two veins (p < 0.05). k-t acceleration of 4D flow MRI is feasible for liver hemodynamic assessment with acceleration factors R = 3 and R = 5 resulting in a scan time reduction of at least 40 % with similar quantitation of liver hemodynamics compared with GRAPPA R = 2.

Variations in the origin of middle hepatic artery: a cadaveric study and implications for living donor liver transplantation.

Living donor liver transplantation has been associated with severe vascular complications like hepatic artery thrombosis, which commonly involves the hepatic segment 4. Most authors have defined the artery to this segment as the middle hepatic artery. The present study was undertaken to characterize the origin of middle hepatic artery and classify the variations observed in cadaveric livers, and also to analyze the significance (if any) of the findings in relation to living donor liver transplantation. The study was conducted on 125 adult livers, without macroscopic abnormalities, retrieved from human cadavers (age, 55-78 years; male, 77; female, 48) obtained from clinical wards. The hepatic arterial system was exposed, the origin of the middle hepatic artery was identified in each liver specimen and the variations observed in its origin were noted across all the specimen. Six types of hepatic arterial configurations were observed based on variations in the origin of middle hepatic artery, taking into consideration the presence of accessory hepatic arteries. It was noted in 19 (15.2%) livers that in the presence of an accessory left hepatic artery, the middle hepatic artery arose as a sub-branch of the right hepatic artery. Presence of the above hepatic arterial configuration in the donor could possibly be associated with an increased risk of intra-operative injury to the middle hepatic artery during right/left lobe living donor liver transplantation and this may subsequently lead to serious post-operative vascular complications like hepatic artery thrombosis.

Laparoscopic management of post-cholecystectomy sectoral artery pseudoaneurysm

Vascular injuries during laparoscopic cholecystectomy can occur similar to biliary injuries and mostly represented by intraoperative bleeding. Hepatic artery system pseudoaneurysm are rare. It occurs in the early or late postoperative course. Patients present with pallor, signs of haemobillia and altered liver function. We report a case of right posterior sectoral artery pseudoaneurysm detected 2 weeks after laparoscopic cholecystectomy and successfully repaired laparoscopically. We also describe how laparoscopic pringle clamping saved the conversion. The actively bleeding right posterior sectoral artery pseudoaneurysm was diagnosed by CT angiogram. Embolisation, usually the treatment of choice, would have risked liver insufficiency as hepatic artery proper was at risk because the origin the bleeding artery was just after its bifurcation. Isolated right hepatic artery embolisation can also cause hepatic insufficiency. To our knowledge this is the first reported case of laparoscopic repair of post-laparoscopic cholecystectomy bleeding sectoral artery pseudoaneurysm.

Computationally Efficient Particle Release Map Determination for Direct Tumor-Targeting in a Representative Hepatic Artery System

Implementation of a novel direct tumor-targeting technique requires a computer modeling stage to generate particle release maps (PRMs) which allow for optimal catheter positioning and selection of best injection intervals for drug-particles. This simulation task for a patient-specific PRM may require excessive computational resources and a relatively long turn-around time for a fully transient analysis. Hence, steady-state conditions were sought which generates PRMs equivalent to the pulsatile arterial flow environment. Fluid-particle transport in a representative hepatic artery system was simulated under fully transient and steady-state flow conditions and their corresponding PRMs were analyzed and compared. Comparisons of the transient PRMs from ten equal intervals of the cardiac pulse revealed that the diastolic phase produced relatively constant PRMs due to its semisteady flow conditions. Furthermore, steady-state PRMs, which best matched the transient particle release maps, were found for each interval and over the entire cardiac pulse. From these comparisons, the flow rate and outlet pressure differences proved to be important parameters for estimating the PRMs. The computational times of the fully transient and steady simulations differed greatly, i.e., about 10 days versus 0.5 to 1 h, respectively. The time-averaged scenario may provide the best steady conditions for estimating the transient particle release maps. However, given the considerable changes in the PRMs due to the accelerating and decelerating phases of the cardiac cycle, it may be better to model several steady scenarios, which encompass the wide range of flows and pressures experienced by the arterial system in order to observe how the PRMs may change throughout the pulse. While adding more computation time, this method is still significantly faster than running the full transient case. Finally, while the best steady PRMs provide a qualitative guide for best catheter placement, the final injection position could be adjusted in vivo using biodegradable mock-spheres to ensure that patient-specific optimal tumor-targeting is achieved. In general, the methodology described could generate computationally very efficient and sufficiently accurate solutions for the transient fluid-particle dynamics problem. However, future work should test this methodology in patient-specific geometries subject to various flow waveforms.

A Comparison of Doubutamine and Levosimendan on Hepatic Blood Flow in Patients with a Low Cardiac Output State after Cardiac Surgery: A Randomised Controlled Study

Liver dysfunction due to a low cardiac output state after cardiac surgery is associated with a poor prognosis, but whether one inotrope is superior to another in improving hepatic perfusion remains uncertain. This study compared the systemic and hepatic haemodynamic effects of levosimendan to dobutamine in patients with a low cardiac output state (cardiac index < 2.2 l/min/m2) after on-pump cardiac surgery. A total of 25 patients were randomised to receive either an intravenous bolus of levosimendan (12 µg/kg) over 15 minutes, followed by an infusion of 0.2 µg/kg/min for 24 hours, or an infusion of dobutamine 7.5 µg/kg/min for 24 hours and completed the study. The systemic and hepatic haemodynamics at 24 and 48 hours were all better after levosimendan than dobutamine (dobutamine group: cardiac index (l/min/m2)=2.51 [standard deviation ±0.29], 2.40±0.23; portal vein flow (ml/min): 614.0±124.7, 585.9±144.8; pulsatility index: 2.02±0,28, 2.98±0.27 versus the levosimendan group: cardiac index: 3.02± 0.27, 2.98± 0.30; portal vein flow: 723.0± 143.5, 702.9±117.8; pulsatility index: 1.71±0.26, 1.73±0.27). The improvement in portal vein blood flow at 48 hours was significantly better after levosimendan than dobutamine (41% vs. 11% increment from baseline, P<0.05). In addition, there was a significant reduction in hepatic artery resistance after levosimendan but not dobutamine (resistance index reduction 6.5% vs. 0%, P<0.05). In summary, levosimendan can be considered as a selective liver vasodilator and can improve hepatic blood flow through both the hepatic artery and portal venous system, whereas dobutamine can only improve the portal venous blood flow without vasodilating the hepatic artery.

Impact of Fluid–Structure Interaction on Direct Tumor-Targeting in a Representative Hepatic Artery System

Direct targeting of solid tumors with chemotherapeutic drugs and/or radioactive microspheres can be a treatment option which minimizes side-effects and reduces cost. Briefly, computational analysis generates particle release maps (PRMs) which visually link upstream particle injection regions in the main artery with associated exit branches, some connected to tumors. The overall goal is to compute patient-specific PRMs realistically, accurately, and cost-effectively, which determines the suitable radial placement of a micro-catheter for optimal particle injection. Focusing in this paper on new steps towards realism and accuracy, the impact of fluid-structure interaction on direct drug-targeting is evaluated, using a representative hepatic artery system with liver tumor as a test bed. Specifically, the effect of arterial wall motion was demonstrated by modeling a two-way fluid-structure interaction analysis with Lagrangian particle tracking in the bifurcating arterial system. Clearly, rapid computational evaluation of optimal catheter location for tumor-targeting in a clinical application is very important. Hence, rigid-wall cases were also compared to the flexible scenario to establish whether PRMs generated when based on simplifying assumptions could provide adequate guidance towards ideal catheter placement. It was found that the best rigid (i.e., time-averaged) geometry is the physiological one that occurs during the diastolic targeting interval.

Reproducibility study of four‐dimensional flow MRI of arterial and portal venous liver hemodynamics: Influence of spatio‐temporal resolution

To evaluate influence of variation in spatio-temporal resolution and scan-rescan reproducibility on three-dimensional (3D) visualization and quantification of arterial and portal venous (PV) liver hemodynamics at four-dimensional (4D) flow MRI. Scan-rescan reproducibility of 3D hemodynamic analysis of the liver was evaluated in 10 healthy volunteers using 4D flow MRI at 3T with three different spatio-temporal resolutions (2.4 × 2.0 × 2.4 mm(3), 61.2 ms; 2.5 × 2.0 × 2.4 mm(3), 81.6 ms; 2.6 × 2.5 × 2.6 mm(3), 80 ms) and thus different total scan times. Qualitative flow analysis used 3D streamlines and time-resolved particle traces. Quantitative evaluation was based on maximum and mean velocities, flow volume, and vessel lumen area in the hepatic arterial and PV systems. 4D flow MRI showed good interobserver variability for assessment of arterial and PV liver hemodynamics. 3D flow visualization revealed limitations for the left intrahepatic PV branch. Lower spatio-temporal resolution resulted in underestimation of arterial velocities (mean 15%, P < 0.05). For the PV system, hemodynamic analyses showed significant differences in the velocities for intrahepatic portal vein vessels (P < 0.05). Scan-rescan reproducibility was good except for flow volumes in the arterial system. 4D flow MRI for assessment of liver hemodynamics can be performed with low interobserver variability and good reproducibility. Higher spatio-temporal resolution is necessary for complete assessment of the hepatic blood flow required for clinical applications.

Variações da artéria hepática: estudo anatômico em cadáveres

to demonstrate the minutiae of hepatic arterial system, the incidence of anatomical variations and to compare data obtained from the literature, thus contributing with students and professionals working in this area. We prepared 45 corpses at the Department of Anatomy of the Pontifical Catholic University of Paraná, between July 2010 and April 2011, of which group 30 displayed integrity of structures. We analyzed the anatomical variations of the hepatic arteries, their main characteristics, such as origin, course, length and diameter. The overall result was expressed as frequency and percentage of cadavers with anatomic variations of the hepatic arterial system. The estimative of this percentage was done by constructing a confidence interval of 95%. There was some kind of anatomical variation in 40% (n = 12) of cadavers. We found 02 variations in the common hepatic artery, 03 in the gastroduodenal artery, 03 in the right hepatic artery, 01 in the left hepatic artery, 01 in the right gastric artery, and 02 in cystic artery. As for the celiac artery, there were variations in length, diameter and height in its origin, which was common on the aorta. The variation of right hepatic artery originating from the superior mesenteric artery was found in 10% (n = 3) of the specimens studied and it was considered the most prevalent type of variation in this study. Changes in hepatic arteries are frequently found and in this study their incidence was 40%, similar to the literature. The most significant change, observed in 10% (3 cases), was the right hepatic artery with its origin in the superior mesenteric artery.

Radiological–Surgical Methods to Identify Celiac–Mesenteric Anomalies of the Hepatic Artery Before Duodenopancreatectomy

IntroductionUp to 45% anatomical variations are found in hepatic arterial system. Identifying these anatomical anomalies before or during surgery would prevent additional morbidity in performing a duodenopancreatectomy. They are routinely identified before surgery using CT imaging, but on certain occasions they are not reported and are only discovered during the surgical operation. The initial retroperitoneal access by the superior mesenteric artery (SMA) will avoid a fairly useless intervention if there is superior mesenteric artery invasion, and will identify the anatomical variations originating in the superior mesenteric artery. These anomalies acquire importance in that their unnoticed injury could lead to severe vascular compromise and/or perioperative bleeding. ObjectivesTo analyze celiac–mesenteric anomalies of the hepatic artery before duodenopancreatectomy using the information from multidetector computed tomography (MDCT) using a non-standardized method, a standardized method with multidimensional reconstruction, and maximum intensity projection (MIP), after initial surgical access to the SMA. Patients and methodsA retrospective study of the clinical, histopathological and surgical variables was conducted on patients with an indication for duodenopancreatectomy in our Department from 2008 until April 2010. A study was performed on the reports made after image acquisition by MDCT. A blind, three-dimensional, MIP reconstruction was performed on all the patients to identify arterial anomalies. A description is given of hepatic artery anomalies after initial access to the SMA. ResultsA total of 61 patients were included in the study. The mean age was 65±11 years, with 33 (54%) males and 28 (46%) females. Vascular anomalies, right hepatic artery (RHA) (SMA) substitute (subst), 5 (8%); RHA (SMA) accessory (acc), 4 (7%); left hepatic artery (LHA) (left gastric artery) (LGA) acc 3 (5%); common hepatic artery (CHA) (SMA) subst 3 (5%); RHA (SMA) acc+LHA (LGA) acc 2 (3%); CHA (aorta) subst, 1 (2%); RHA+RGA+2 LHA (celiac trunk), 1 (2%); and CHA (SMA)+LHA (LGA) acc. ConclusionOn being able to identify arterial anomalies with a mixture of preoperative radiological and methodological criteria, with three-dimensional reconstruction, MIP, and initially performing a dissection of the superior mesenteric artery could avoid duodenopancreatectomies that may not benefit the patient and compromise bleeding.

Chemoembolization and Radioembolization for Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) continues to represent a major worldwide problem. Although treatments such as resection, transplantation, and ablation may provide a chance for a cure, these options are often precluded because of advanced disease presentation. Palliative treatments include transarterial embolization and systemic therapies. This review will summarize the state of the science for embolic therapies in HCC (conventional and drug-eluting chemoembolization, radioembolization) as well as discuss related topics including HCC staging, assessment of response, and ongoing clinical trials.

Hepatic Venous Occlusion During Cardiopulmonary Bypass in Patients With Heterotaxy Syndrome: A Safe but Underutilized Option

Direct intracardiac drainage of separate right and left hepatic veins remote from each other (independent hepatic veins) in heterotaxy patients complicates procedures requiring cardiopulmonary bypass (CPB). Temporary occlusion of such independent hepatic veins during CPB is an alternative to cannulation but is rarely used because of concerns about acute congestive hepatopathy. Consequently, temporary single hepatic venous occlusion has not been well described as a safe and simple alternative to hepatic venous cannulation during CPB. We report 2 patients with the polysplenia variant of heterotaxy in whom independent hepatic veins were safely occluded for 55 and 86 minutes, respectively, in the course of intracardiac repair. Temporary hepatic venous occlusion simplified the CPB technique and minimized clutter of the operative field. The intrahepatic hemodynamics during CPB using temporary hepatic venous occlusion is illustrated.

Métodos radiológico-quirúrgicos para la identificación de anomalías celiaco-mesentéricas de la arteria hepática ante una duodenopancreatectomía

IntroductionUp to 45% anatomical variations are found in hepatic arterial system. Identifying these anatomical anomalies before or during surgery would prevent additional morbidity in performing a duodenopancreatectomy. They are routinely identified before surgery using CT imaging, but on certain occasions they are not reported and are only discovered during the surgical operation. The initial retroperitoneal access by the superior mesenteric artery (SMA) will avoid a fairly useless intervention if there is superior mesenteric artery invasion, and will identify the anatomical variations originating in the superior mesenteric artery. These anomalies acquire importance in that their unnoticed injury could lead to severe vascular compromise and/or perioperative bleeding. ObjectivesTo analyse celiac-mesenteric anomalies of the hepatic artery before duodenopancreatectomy using the information from multidetector computed tomography (MDCT) using a non-standardised method, a standardised method with multidimensional reconstruction, and maximum intensity projection (MIP), after initial surgical access to the SMA. Patients and methodsA retrospective study of the clinical, histopathological and surgical variables was conducted on patients with an indication for duodenopancreatectomy in our Department from 2008 until April 2010. A study was performed on the reports made after image acquisition by MDCT. A blind, three-dimensional, MIP reconstruction was performed on all the patients to identify arterial anomalies. A description is given of hepatic artery anomalies after initial access to the SMA. ResultsA total of 61 patients were included in the study. The mean age was 65±11 years, with 33 (54%) males and 28 (46%) females. Vascular anomalies, right hepatic artery (RHA) (SMA) substitute (subst), 5 (8%); RHA (SMA) accessory (acc), 4 (7%); left hepatic artery (LHA) (left gastric artery) (LGA) acc 3 (5%); common hepatic artery (CHA) (SMA) subst 3 (5%); RHA (SMA) acc+LHA (LGA) acc2 (3%); CHA (aorta) subst, 1 (2%); RHA+RGA+2 LHA (celiac trunk), 1 (2%); and CHA (SMA)+LHA (LGA) acc. ConclusionOn being able to identify arterial anomalies with a mixture of preoperative radiological and methodological criteria, with three-dimensional reconstruction, MIP, and initially performing a dissection of the superior mesenteric artery could avoid duodenopancreatectomies that may not benefit the patient and compromise bleeding.

A Basic Consideration for Porcine Liver Preservation Using a Novel Continuous Machine Perfusion Device

IntroductionThe aims of this study were to compare extracellular and intracellular-type University of Wisconsin (UW) solutions for liver grafts and to assess oxygenation in this perfusion system. Materials and MethodsThe organ preservation system consisted of 3 circulating systems for the portal vein, hepatic artery, and maintenance of the perfusion solution. The portal vein or hepatic artery system had a roller pump, a flow meter, and a pressure sensor. In this study, we perfused livers with UW or extracellular type UW-gluconate at 4°C–6°C for 4 hours. The flow rates at the entrance were 0.5 mL/min/g liver in the portal vein and 0.2 mL/min/liver in the hepatic artery. Orthotopic liver transplantation was performed in pigs: group 1-a, grafts procured after acute hemorrhagic shock were preserved by a solution without O2; group 1-b, grafts were preserved with O2; group 2-a, grafts were perfused using intracellular type solution (UW); and group 2-b, grafts were perfused using extracellular-type solution (UW-gluconate). ResultsEffluent aspartate aminotransferase (AST) and lactate dehydrogenase (LDH) levels in group 1-b were lower than those in group 1-a. Survival rates in group 2-a and group 2-b were 1/4 and 3/3, respectively. Effluent AST and LDH levels in the perfusate of group 2-b were lower than group 2-a. Histological study revealed necrosis of hepatocytes and sinusoidal congestion in group 2-a. ConclusionA beneficial effect of extracellular-type solution with oxygenation in a novel continuous machine preservation system yielded well-preserved liver graft function.

A New Catheter for Tumor-Targeting With Radioactive Microspheres in Representative Hepatic Artery Systems—Part II: Solid Tumor-Targeting in a Patient-Inspired Hepatic Artery System

In this second part, the methodology for optimal tumor-targeting is further explored, employing a patient-inspired hepatic artery system which differs significantly from the idealized configuration discussed in Part I. Furthermore, the fluid dynamics of a microsphere supply apparatus is also analyzed. The best radial catheter positions and particle-release intervals for tumor targeting were determined for both the idealized and patient-inspired configurations. This was accomplished by numerically analyzing generated particle release maps (PRMs) for ten equally spaced intervals throughout the pulse. As in Part I, the effects of introducing a catheter were also investigated. In addition to the determination of micro-catheter positioning and, hence, optimal microsphere release, a microsphere-supply apparatus (MSA) was analyzed, which transports the particles to the catheter-nozzle, considering different axial particle injection functions, i.e., step, ramp, and S-curve. A refined targeting methodology was developed which demonstrates how the optimal injection region and interval can be determined with the presence of a catheter for any geometric configuration. Additionally, the less abrupt injection functions (i.e., ramp and S-curve) were shown to provide a more compact particle stream, making them better choices for targeting. The results of this study aid in designing the smart micro-catheter (SMC) in conjunction with the MSA, bringing this innovative treatment procedure one step closer to implementation in clinical practice.

A New Catheter for Tumor Targeting With Radioactive Microspheres in Representative Hepatic Artery Systems. Part I: Impact of Catheter Presence on Local Blood Flow and Microsphere Delivery

Building on previous studies in which the transport and targeting of (90)Y microspheres for liver tumor treatment were numerically analyzed based on medical data sets, this two-part paper discusses the influence of an anchored, radially adjustable catheter on local blood flow and microsphere delivery in an idealized hepatic artery system (Part I). In Part II a patient-inspired case study with necessary conditions for optimal targeting of radioactive microspheres (i.e., yttrium 90) onto liver tumors is presented. A new concept of optimal catheter positioning is introduced for selective targeting of two daughter-vessel exits potentially connected to liver tumors. Assuming laminar flow in rigid blood vessels with an anchored catheter in three controlled positions, the transient three-dimensional (3D) transport phenomena were simulated employing user-enhanced engineering software. The catheter position as well as injection speed and delivery function may influence fluid flow and particle transport. Although the local influences of the catheter may not be negligible, unique cross-sectional particle release zones exist, with which selectively the new controlled targeting methodology would allow optimal microsphere delivery. The insight gained from this analysis paves the way for improved design and testing of a smart microcatheter (SMC) system as well as new investigations leading to even more successful treatment with (90)Y microspheres or combined internal radiation and chemotherapy.

Rare Hepatic Arterial Anatomic Variants in Patients Requiring Pancreatoduodenectomy and Review of the Literature

Normal hepatic arterial anatomy occurs in approximately 50–80% of cases; for the remaining cases, multiple variations have been described. Knowledge of these anomalies is especially important in hepatobiliary and pancreatic surgery in order to avoid unnecessary complications. We describe two cases of patients undergoing pancreatoduodenectomy for abnormalities in the head of the pancreas. Preoperative contrast-enhanced cross-sectional imaging demonstrated relevant, rare hepatic arterial variants: (1) a completely replaced hepatic arterial system with a gastroduodenal artery (GDA) arising directly from the celiac axis and (2) a replaced right hepatic artery originating from the superior mesenteric artery and traveling anterior to the pancreatic uncinate process and head. These findings were confirmed during pancreatoduodenectomy. Both of these variants have been rarely described with an incidence of <1.0%. In the present paper, we describe the hepatic arterial anomalies commonly encountered and clarify the important details associated with these variants as they pertain to pancreatoduodenectomy.

Experimental Microsphere Targeting in a Representative Hepatic Artery System

Recent work employing the computational fluid-particle modeling of the hepatic arteries has identified a correlation between particle release position and downstream branch distribution for direct tumor-targeting in radioembolization procedures. An experimental model has been constructed to evaluate the underlying simulation theory and determine its feasibility for future clinical use. A scaled model of a generalized hepatic system with a single inlet and five outlet branches was fabricated to replicate the fluid dynamics in the hepatic arteries of diseased livers. Assuming steady flow, neutrally buoyant microspheres were released from controlled locations within the inlet of the model and the resulting output distributions were recorded. Fluid and particle transport simulations were conducted with identical parameters. The resulting experimentally and simulation-derived microsphere distributions were compared. The experimental microsphere distribution exhibited a clear dependence on injection location that correlated very strongly with the computationally predicted results. Individual branch targeting was possible for each of the five outputs. The experimental results validate the simulation methodology for achieving targeted microsphere distributions in a known geometry under constant flow conditions.

Porcine Ex Vivo Liver Phantom for Dynamic Contrast-Enhanced Computed Tomography

: To demonstrate the feasibility of developing a fixed, dual-input, biologic liver phantom for dynamic contrast-enhanced computed tomography (CT) imaging and to report initial results of use of the phantom for quantitative CT perfusion imaging. : Porcine livers were obtained from completed surgical studies and perfused with saline and fixative. The phantom was placed in a body-shaped, CT-compatible acrylic container and connected to a perfusion circuit fitted with a contrast injection port. Flow-controlled contrast-enhanced imaging experiments were performed using 128-slice and 64-slice dual-source multidetector CT scanners. CT angiography protocols were used to obtain portal venous and hepatic arterial vascular enhancement, reproduced over a period of 4 to 6 months. CT perfusion protocols were used at different input flow rates to correlate input flow with calculated tissue perfusion, to test reproducibility, and to determine the feasibility of simultaneous dual-input liver perfusion. Histologic analysis of the liver phantom was also performed. : CT angiogram 3-dimensional reconstructions demonstrated homogenous tertiary and quaternary branching of the portal venous system to the periphery of all lobes of the liver as well as enhancement of the hepatic arterial system to all lobes of the liver and gallbladder throughout the study period. For perfusion CT, the correlation between the calculated mean tissue perfusion in a volume of interest and input pump flow rate was excellent (R = 0.996) and color blood flow maps demonstrated variations in regional perfusion in a narrow range. Repeat perfusion CT experiments demonstrated reproducible time-attenuation curves, and dual-input perfusion CT experiments demonstrated that simultaneous dual input liver perfusion is feasible. Histologic analysis demonstrated that the hepatic microvasculature and architecture appeared intact and well preserved at the completion of 4 to 6 months of laboratory experiments and contrast-enhanced imaging. : We have demonstrated successful development of a porcine liver phantom using a flow-controlled extracorporeal perfusion circuit. This phantom exhibited reproducible dynamic contrast-enhanced CT of the hepatic arterial and portal venous system over a 4- to 6-month period.

Laparoscopic Right Hepatectomy With Intrahepatic Transection of the Right Bile Duct

Although our earlier videos demonstrated extrahepatic control of the hepatic arterial, portal venous, and biliary system, we have begun transecting the biliary system intraparenchymally for lesions distant from hilar plate and the confluence of the right and left hepatic ducts.1 (-) 3 The patient was a 50-year old gentleman with synchronous colorectal hepatic metastasis, who underwent 6 cycles of neoadjuvant chemotherapy with a Folfox-based regimen followed by laparoscopic right hepatectomy plus wedge resection of segment 4 and microwave ablation for a lesion in segment 2. This was followed 1month later by laparoscopic proctocolectomy. Of note, the patient was also treated with Avastin for 1month, which was stopped 2months prior to his liver surgery. Pneumoperitoneum was obtained with the Veress needed; alternatively, the open technique may need to be used in patients who have undergone previous surgery. A 12-mm blunt tip balloon trocar was placed approximately 1 hand-breadth below the right costal margin. Two 12-mm working trocars were placed to the left and right of this optic trocar, and trocars were then placed in the left sub xiphoid region and in the right flank for the assistants. The right hepatic artery was triply clipped proximally and twice distally prior to being sharply transected. The right hepatic portal vein was then transected using a laparoscopic vascular GIA stapler device (TriStapler, Covidien, Norwalk, CT). The anterior surface of the liver was examined, and there was a clear line of demarcation along Cantlie's line. Using the ultrasonic shears (Harmonic Scalpel, Ethicon, Cincinnati, OH), the liver parenchyma was then transected. In the area of the right hepatic duct, the liver parenchyma was transected with a single firing of the laparoscopic GIA vascular stapler device. The right hepatic vein was then identified and similarly transected with a single firing of the laparoscopic vascular GIA stapler device. Hemostasis along the hepatic parenchyma was reinforced with the laparoscopic bipolar device. The two trocars on the right of the patient are connected into 1 incision, and a gel port is placed to facilitate removal of the specimen; alternatively, an old incision can be used. For patients who will need a laparoscopic or open colectomy, a lower midline incision is made. From Jan 2009 to Oct 2010, 13 patients underwent right hepatectomy. The average age was 63.5years (range, 46-87years). The indication for surgery were all for cancer including 11 colorectal metastasis, 1 anal cancer metastasis, and 1 cholangiocarcinoma. In these 13 patients, 1 patient (7.7%) required conversion to an open approach because of bleeding, 1 additional patient required laparoscopic hand assistance, and the remaining patients were completed laparoscopically. There were no surgical mortalities at 30 or 90days. Complications occurred in 2 (15%) patients, and included 1 patient who was converted to an open procedure because of hemorrhage and was complicated by a bile leak; the second patient with complication also developed a 1-bile leak, both of which responded to percutaneous treatments. The mean hospital stay was 7.7days (range, 5-17days). The mean operative time was 401min (range, 220-600min). The mean estimated blood loss was 878cm(3) (range, 100-3,000cm(3)). All patients underwent an R0 resection. Laparoscopic major hepatectomy is feasible. As in open hepatectomies, intrahepatic transection of the right bile duct may be safer because there is a decreased risk of injury to the left hepatic duct.4 (,) 5 Larger series with longer-term follow-up are necessary.

Computational Fluid Dynamics Modeling of 90Y Microspheres in Human Hepatic Tumors

The number of patients afflicted with liver tumors continues to rise being a major concern of international healthcare. Yttrium-90 microsphere radioembolization can be an effective and safe treatment of unresectable primary and secondary liver tumors, and has the potential to be a forefront treatment option for tumor-afflicted patients. Computational fluid-particle dynamics is a powerful research tool that can be used to understand the underlying physics of Yttrium-90 microsphere transport and deposition, leading to improved clinical strategies and ultimately to a better treatment of tumor-afflicted patients. Two representative, patient-inspired three-dimensional geometries of the hepatic arterial system with assumed connections to liver tumors have been considered. Experimentallyvalidated computational fluid-particle dynamics modeling results have shown the significant influence of vessel morphology, downstream resistance to flow, catheter radial and axial location associated with microsphere injection time interval, and injection velocity on microsphere transport through the hepatic arterial system. Moreover, the computational investigations have identified the ability to preferentially deliver microspheres to a specific arterial vessel outlet, presumably connected to a tumor, by selecting appropriate temporal and spatial parameters of the microsphere injection. As the computational findings are extended to additional experiments as well as nextgeneration smart micro-catheters, clinicians can implement a refined set of treatment strategies that utilize the aforementioned physical phenomena. Computational fluid-particle dynamics models have thus provided valuable physical insight as well as suggestions for the improvement of current Yttrium-90 microsphere radioembolization treatment. Additional computational investigations are needed to create more encompassing conclusions from a large collection of patient-specific analyses plus the design, prototyping, and testing of a new smart micro-catheter and high-resolution imaging devices that give radiation and interventional oncologists new degrees of control and precision when administering Yttrium-90 microsphere radioembolization.