Preoperative imaging of left portal vein at the Rex recess for Rex shunt formation using wedged hepatic vein carbon dioxide portography

Intrahepatic portal venous systems in adult patients with cavernous transformation of portal vein: Imaging features and a new classification

BACKGROUND

Cavernous transformation of the portal vein (CTPV) due to portal vein obstruction is a rare vascular anomaly defined as the formation of multiple collateral vessels in the hepatic hilum. This study aimed to investigate the imaging features of intrahepatic portal vein in adult patients with CTPV and establish the relationship between the manifestations of intrahepatic portal vein and the progression of CTPV.

METHODS

We retrospectively analyzed 14 CTPV patients in Beijing Tsinghua Changgung Hospital. All patients underwent both direct portal venography (DPV) and computed tomography angiography (CTA) to reveal the manifestations of the portal venous system. The vessels measured included the left portal vein (LPV), right portal vein (RPV), main portal vein (MPV) and the portal vein bifurcation (PVB).

RESULTS

Nine males and 5 females, with a median age of 40.5 years, were included in the study. No significant difference was found in the diameters of the LPV or RPV measured by DPV and CTA. The visualization in terms of LPV, RPV and PVB measured by DPV was higher than that by CTA. There was a significant association between LPV/RPV and PVB/MPV in term of visibility revealed with DPV (P = 0.01), while this association was not observed with CTA. According to the imaging features of the portal vein measured by DPV, CTPV was classified into three categories to facilitate the diagnosis and treatment.

CONCLUSIONS

DPV was more accurate than CTA for revealing the course of the intrahepatic portal vein in patients with CTPV. The classification of CTPV, that originated from the imaging features of the portal vein revealed by DPV, may provide a new perspective for the diagnosis and treatment of CTPV.

Clinically Oriented Classification of Anatomic Variants of the Umbilical Fissure for Ligamentum Teres in the Human Liver

Background In the classic descriptions of the human liver, the umbilical fissure (UF) is a long, narrow groove on the visceral surface that receives the ligamentum teres hepatis. In this study, we document the UF variations encountered in a series of cadaveric dissections. Methods We reported UF variations using the following classification: Type I refers to "normal" anatomy where there is a long, narrow groove. In type II, the UF was covered by a fibrotic band devoid of hepatic parenchyma. In type III variants, an extension of hepatic parenchyma partially covered but did not obliterate the UF. In type IV variants, the hepatic parenchyma formed a bridge over the UF, completely obliterating the groove. After institutional review board approval, we observed all consecutive cadaveric dissections over five years and recorded the characteristics and dimensions of each UF and its immediate relations. Results There were 69 cadavers, and variant UFs were present in 38 (55.1%) cadavers: type II (1.5%), type III (20.3%), and type IV (33.3%). Conclusions In this Jamaican population, only 44.9% of persons had conventional "normal" anatomy and 55.1% had UF variants. These variants are clinically significant, as they lead to misinterpretation of patient imaging and can hinder operative procedures on the liver.

Human liver umbilical fissure variants: pons hepatis (ligamentum teres tunnel)

PURPOSE

In the classical description of normal liver anatomy, the umbilical fissure is a long, narrow groove that receives the ligamentum teres hepatis. The pons hepatis is an anatomic variant, where the umbilical fissure is converted into a tunnel by an overlying bridge of liver parenchyma. We carried out a study to evaluate the existing variations of the umbilical fissure in a Caribbean population.

METHODS

We observed all consecutive autopsies performed at a facility in Jamaica and selected cadavers with a pons hepatis for detailed study. A pons hepatis was considered present when the umbilical fissure was covered by hepatic parenchyma. We recognized two variants: an open-type (incomplete) pons hepatis in which the umbilical fissure was incompletely covered by parenchyma ≤ 2 cm in length and a closed type (complete) pons hepatis in which the umbilical fissure was covered by a parenchymal bridge > 2 cm and thus converted into a tunnel. We measured the length (distance from transverse fissure to anterior margin of the parenchymatous bridge), width (extension across the umbilical fissure in a coronal plane) and thickness (distance from the visceral surface to the hepatic surface measured at the mid-point of the parenchymal bridge in a sagittal plane) of each pons hepatis. A systematic literature review was also performed to retrieve data from relevant studies. The raw data from these retrieved studies was used to calculate the global point prevalence of pons hepatis and compared the prevalence in our population.

RESULTS

Of 66 autopsies observed, a pons hepatis was present in 27 (40.9%) cadavers. There were 15 complete variants, with a mean length of 34.66 mm, mean width of 16.98 mm and mean thickness of 10.98 mm. There were 12 incomplete variants, with a mean length of 17.02 mm, width of 17.03 mm and thickness of 9.56 mm. The global point prevalence of the pons hepatis (190/5515) was calculated to be or 3.45% of the global population.

CONCLUSIONS

We have proposed a classification of the pons hepatis that is reproducible and clinically relevant. This allowed us to identify a high prevalence of pons hepatis (41%) in this Afro-Caribbean population that is significantly greater than the global prevalence (3.45%; P < 0.0001).

Pediatric Hepatobiliary Interventions in the Setting of Intrahepatic Vascular Malformations, Portal Hypertension, and Liver Transplant

Within the broad spectrum of pediatric hepatobiliary disorders, hepatic vascular malformations, portal hypertension, and hepatic transplant interventions pose numerous challenges. The role of interventional radiology within each of these conditions is discussed herein, beginning with endovascular management of high flow hepatic vascular malformations. Next, while becoming less common in adult populations, surgical portoportal and portosystemic shunts remain prevalent in many pediatric centers. Shunt anatomy is reviewed along with endovascular management techniques for shunt dysfunction. Next, the growing experience with pediatric transjugular intrahepatic portosystemic shunt placement is reviewed along with tips for success in pediatric patients. Finally, pediatric hepatic transplant interventions are discussed with technical notes pertinent to split liver anatomy.

Advances in the management of childhood portal hypertension

Portal hypertension is one of the most serious complications of childhood liver disease, and variceal bleeding is the most feared complication. Most portal hypertension results from cirrhosis but extra hepatic portal vein obstruction is the single commonest cause. Upper gastrointestinal endoscopy endoscopy remains necessary to diagnose gastro-esophageal varices. Families of children with portal hypertension should be provided with written instructions in case of gastrointestinal bleeding. Children with large varices should be considered for primary prophylaxis on a case-by-case basis. The preferred method is variceal band ligation. Children with acute bleeding should be admitted to hospital and treated with antibiotics and pharmacotherapy before urgent therapeutic endoscopy. All children who have bled should then receive secondary prophylaxis. The preferred method is variceal band ligation and as yet there is little evidence to support the use of β-blockers. Children with extrahepatic portal vein obstruction should be assessed for suitability of mesoportal bypass.

Intrahepatic portal venous systems in children with noncirrhotic prehepatic portal hypertension: anatomy and clinical relevance

BACKGROUND

Children with extrahepatic portal hypertension typically present with cavernomatous transformation of the portal vein and a poorly defined intrahepatic portal vein system on conventional imaging. With the Meso-Rex Bypass becoming the gold-standard intervention for a cure, a precise assessment of the intrahepatic portal vein system provides helpful data for deciding whether a Meso-Rex Bypass is feasible or not.

METHODS

All children with extrahepatic portal hypertension were prospectively assessed by wedged hepatic venous portography. Venous anatomy was categorized into five subtypes (A to E), depending on the presence of thrombosis in the Rex recessus, or not, and its extension within the intrahepatic portal venous system.

RESULTS

Eighty-nine children entered the study. Previous umbilical vein catheterization is usually associated with Rex thrombosis, while the Rex recessus and the intrahepatic portal venous system are patent in idiopathic cases, thus allowing for the performance of a Meso-Rex Bypass with a good outcome.

CONCLUSIONS

Wedged hepatic venous portography is a very effective tool for detailed preoperative assessment and identification of children being considered for Meso-Rex Bypass surgery. An anatomic-radiological classification is useful in selecting patients for Meso-Rex Bypass with anticipation of a high rate of success.

Surgical management of portal hypertension in children

The management of children with portal hypertension has dramatically changed during the past decade, with an improvement in outcome. This has been achieved by improved efficiency of endoscopic variceal control and the success of liver transplantation. Emergency surgical shunt procedures are rarely required, with acute bleeding episodes generally controlled endoscopically or, occasionally in adults, by interventional radiological procedures. Portosystemic shunts may be considered as a bridge to transplant in adults but are rarely used in this context in children. Nontransplant surgery or radiological interventions may still be indicated for noncirrhotic portal hypertension when the primary cause can be cured and to allow normalization of portal pressure before liver parenchyma is damaged by chronic secondary changes in some specific diseases. The meso-Rex bypass shunt is used widely but is limited to those with a favorable anatomy and can even be performed preemptively. Elective portosystemic shunt surgery is reserved for failure to respond to conservative management in the absence of alternative therapies.

Pre- and postoperative imaging of the Rex shunt in children: what radiologists should know

OBJECTIVE

The objective of this article is to illustrate the imaging features of patients with extrahepatic portal venous obstruction who are evaluated before or after a Rex shunt surgery.

CONCLUSION

The Rex shunt is a potentially curative surgical procedure that reestablishes physiologic hepatopetal portal flow. It is typically accomplished by interposing a vascular conduit between the superior mesenteric vein to the still patent intrahepatic portal venous system. This procedure results in resolution of portal hypertension.

Pre- and postoperative imaging and interventions for the meso-Rex bypass in children and young adults

The meso-Rex bypass is a physiological and anatomical bypass procedure for relief of extrahepatic portal vein obstruction and restoration of mesenteric venous return to the liver. Most patients who are candidates for the bypass are children or young adults with portal hypertension and hypersplenism secondary to cavernous transformation of the portal vein. Most frequently, the bypass utilizes an autologous venous graft to connect the intrahepatic left portal vein to the infrapancreatic superior mesenteric vein (SMV) re-establishing first-pass portal perfusion. We describe the preoperative imaging of the 92 bypass candidates, the surgical anatomy as reflected in postoperative imaging, and the imaging of bypass complications at our institution.Preoperative imaging with US, CT and MR is directed to demonstrate patency and size of the left portal vein and SMV, to define the extent of cavernous transformation and splanchnic collaterals, and to assess for any associated abdominal vascular or solid organ abnormalities. Postoperative imaging is aimed at diagnosing meso-Rex bypass stenosis or occlusion and the interventional management of these complications.

Imaging the Rex vein preoperatively using wedged hepatic venous portography

BACKGROUND

Mesentericoportal bypass, the Rex shunt, restores the physiological hepatic portal flow and reduces the clinical sequelae of portal hypertension in children with extrahepatic portal vein obstruction (EHPVO). The preoperative evaluation includes an accurate assessment of the portal venous inflow and outflow. The former is readily assessed by ultrasound and MRI, while the outflow intrahepatic portal vein is harder to assess.

PURPOSE

To assess the efficacy of wedged hepatic venous portography (WHVP) at detecting a patent Rex vein preoperatively in children with EHPVO who were considered for mesenterico-portal bypass.

MATERIALS AND METHODS

A single-institution retrospective chart review was undertaken for children with EHPVO who had been considered for a mesoportal bypass between January 2001 and January 2010.

RESULTS

Sixteen children were considered for mesoportal bypass, including four post reduced-size liver transplant patients. Ten children (63%) underwent WHVP. The Rex vein was clearly identified in 8/10 (80%). One Rex vein was seen at surgery but not demonstrated at WHVP. Six mesoportal bypasses were performed without WHVP, of which three (50%) were successful.

CONCLUSION

WHVP had a sensitivity of more than 80% and specificity of 100% in the preoperative patency assessment of the Rex vein.

Paediatric chronic liver diseases: how to investigate and follow up? Role of imaging in the diagnosis of fibrosis

Chronic liver diseases are rare in children, but encompass a wide spectrum of disorders that may all be complicated by liver fibrosis and therefore by portal hypertension. They may be classified according to the level of portal flow obstruction: prehepatic, intrahepatic or suprahepatic. Most of them, except presinusoidal diseases, may progress to cirrhosis that carries additional risks of impaired liver function and development of hepatocellular carcinoma. Imaging plays an important role in guiding the diagnosis and biopsy and for follow-up during treatment. US, with high-frequency transducers and Doppler, is the first modality of choice, directs the rest of the investigations and guides interventional radiology. MDCT has made great progress and has replaced angiography for diagnostic purposes. MRI is indicated for parenchyma and nodule characterization and for biliary tract evaluation. To avoid liver biopsy, several elasticity imaging techniques have been developed and have to be evaluated for accuracy and convenience in children. The role of each modality with main imaging findings is described in extrahepatic portal vein obstruction, hepatoportal sclerosis, congenital hepatic fibrosis, cirrhosis and Budd-Chiari syndrome.