| Background and objectivesCavernous transformation of the portal vein(CTPV)refers to the partial or complete obstruction of the main portal vein and/or its branches.The body establishes collateral circulation around the portal vein to relieve persistent portal hypertension.It is named because of the sponge-like shape.CTPV is a rare disease in children with the underlying etiologies remaining unknown.The majority of children aged 1-6 years old are susceptible to recurrent variceal hemorrhage that severely endangers patients.Early diagnosis and treatment of cavernous transformation of portal vein in children play an important role in reducing the risk of gastrointestinal bleeding and improving prognosis.The Rex shunt is currently considered as a curative surgical intervention for the CTPV without additional liver lesions by some surgeons.But difficult surgical techniques resulting from irregular vascular courses prone to bleeding impeded its widespread application at present.Imaging examination plays a decisive role in determining whether cavernous transformation of portal vein requires a Rex shunt and the curative effect after the operation.At present,color Doppler ultrasonography(CDUS)has become the first choice for the diagnosis of cavernous transformation of the portal vein and the preoperative and postoperative evaluation of the Rex shunt because of its convenience,non-invasive,and non-radiation.With the development of CT reconstruction technology,multi-detector row CT portography(MDCTP)is more and more widely used in preoperative evaluation and postoperative efficacy evaluation of the Rex shunt.However,there are few reports on the study of CDUS and MDCTP before and after the Rex shunt,with comparative experience extremely limited.Classical Rex shunt uses autologous bypass vessels to drain blood from the superior mesenteric vein(SMV)into the left portal vein(LPV),thereby restoring physiological intrahepatic blood perfusion and reducing the pressure on the portal vein and visceral bed.The modified Rex transposition anastomoses the open and dilated branches of the extrahepatic portal vein,such as a splenic vein directly to the left portal vein,which simplifies the surgical procedure.For a few children with small Rex recess or dysplasia of the left portal vein,the round ligament of the liver was dilated into a recanalized umbilical vein(UV)instead of the left portal vein.Since 2010,our center has made certain achievements in the application of the traditional Rex shunt(classical Rex shunt and modified Rex transposition)and the new Rex shunt with a recanalized umbilical vein in the treatment of CTPV in children,but some cases recurred after an operation.Based on the analysis of the imaging data of CDUS and MDCTP in CTPV children treated by Rex shunt,the value of two approaches in preoperative evaluation and postoperative follow-up of Rex shunt,and the surgical effects of different traditional Rex shunt and new Rex shunt with recanalized umbilical vein were systematically studied.It is expected to provide an important reference basis for clinical diagnosis,selection of imaging modalities,and surgical procedures.Part I Imaging diagnosis of cavernous transformation of the portal vein in children and preoperative imaging evaluation of Rex shuntObjectivesTo explore the pathogenesis of CTPV from the perspective of imaging,analyze the characteristics of collateral circulation,observe the imaging features of CTPV in children,and assess for the advantages and disadvantages of CDUS and MDCTP in the diagnosis and the diagnostic capabilities of imaging modalities used for preoperative Rex shunt planning.MethodsFrom March 2010 to March 2019,48 CTPV children who received Rex and splenorenal shunt with complete medical records and imaging data in the Second Hospital of Shandong University were included in this study.The preoperative imaging data of CDUS and MDCTP were analyzed retrospectively.The review demonstrated imaging classification of CTPV,the involvement scope,complications,and collateral formation of various types of lesions,and then analyzed the spread route and pathogenesis of the lesions.The imaging features of CTPV in children and the preoperative imaging evaluating for implementation conditions of the Rex shunt was also described.Transvenous portography was used as the standard to compare the ability of the two imaging approaches for confidently determining left portal vein(LPV)patency,superior mesenteric vein(SMV)patency,and contiguity of intrahepatic left and right portal vein.Results1.According to the location of the main portal vein and branches involved,CTPV lesions were divided into three types.Type I was the main portal vein type(13/48 cases,27.1%).Type II was the main portal vein and left and/or right branch type,and this type was also mixed(29/48 cases,60.4%).Type III was the left and right branch type(6/48 cases,12.5%).The lesions were limited to the left and right intrahepatic portal veins and a few segmental branches.Type II of the main portal vein and left and/or right branch accounted for the highest proportion(60.4%)in three categories of CTPV lesions.Among the 35 cases of left and right PV lesions,the ratio of the initial part of the right PV(97.1%)and the transverse and sagittal part of the left PV(100%)was the uppermost.Of the 48 children with CTPV,18 cases were complicated with congenital malformations(37.5%).Type Ⅱ was the most common(48.3%),and the incidences of hepatobiliary and heart malformations(17.2%and 13.8%)were more than those of the other two types.2.Among the collateral vessels in 48 cases of CTPV,the esophagogastric veins were the most common(100%),followed by peri-gallbladder veins(50%)and intestinal and retroperitoneal venous plexus(39.6%).Esophagogastric veins were detected in all children with 3 types.The occurrence rates(62.1%,44.8%,20.7%,20.7%)of pericholecystic veins,intestinal and retroperitoneal venous plexus,other collateral vessels and spontaneous splenorenal shunt in type Ⅱ were higher than those in type Ⅰ and type Ⅲ.The LGV diameter of type Ⅱ was significantly larger than that of the other two types(P<0.05),but there was no significant difference between type Ⅰ and type Ⅲ(P=0.235).3.CDUS showed abnormal portal vein structure with uneven thickening of the wall,enhanced echo,and slender diameter.Around the portal vein,irregular tubular reticular echoes could be seen,showing honeycomb-like changes with color blood flow signals inside and the blood flow speed was slow.MDCTP showed that the normal portal vein structure disappeared and was replaced by multiple vascular masses with tortuous reticular or sinus-like structure.The main portal vein and its left and right branches were stenosed or occluded.In addition to the collateral circulation around the gastroesophagus,gallbladder and retroperitoneum,spontaneous splenorenal shunt could also be found.CDUS and MDCTP reliably enabled detection of the splenic vein in 100%of the studies,but the ability to find the superior mesenteric vein and left gastric vein varied widely.CDUS definitively answered this question in only 64.6%and 12.5%,which was significantly lower than that of MDCTP(100%and 100%).MDCTP performed well in examing collateral vessels such as esophagogastric venous plexus,peri-gallbladder vein,intestinal and retroperitoneal venous plexus,rectal venous plexus and spontaneous splenorenal shunt,enabling confident diagnosis in 100%of the examinations.Conversely,the confident diagnosis could be made in only 72.9%,70.8%,10.5%,0%,and 28.6%of CDUS examinations respectively.4.CDUS and MDCTP adequately assessed the status of left PV in 75%and 79.2%of studies respectively,with no significant difference(P=0.627).However,MDCTP enabled the determination of SMV patency and PV continuity in 100%and 41.7%of the studies,and CDUS was definitively diagnostic in only 64.6%and 12.5%of the examinations.There were statistically significant differences between modalities(P<0.001,P=0.001).The Youden index of MDCTP in predicting these three conditions was 0.95,0.98,and 0.89 respectively,which were higher than those of CDUS(0.89,0.90,and 0.80).Conclusion1.Most CTPV lesions begun from the main portal vein and gradually extended to intrahepatic branches.The spread route of the lesions was from the trunk of the portal vein to the transverse and sagittal part of the left branch or to the initial part of the right branch.Congenital malformation of the portal vein may be the most likely cause of cavernous transformation of portal vein in children.2.Gastroesophageal varices were the most common portosystemic shunt in children with CTPV.Gastroesophageal varices and left gastric vein dilatation of typeⅡ were more obvious than that of the other two types,resulting in more serious symptoms of portal hypertension and a higher risk of upper gastrointestinal bleeding.3.CDUS can easily observe the lesions and blood flow status of portal vein branches,while MDCTP-MIP,MPR and VR images can visually display the lesion area and the adjacent relationship around the blood vessels,which can provide detailed anatomical information of the main portal vein,intrahepatic and extrahepatic branches,and all collateral vessels.4.In terms of sensitivity and specificity,MDCTP is superior to CDUS.MDCTP should be preferred for preoperative evaluation of the Rex shunt because it provided the greater diagnostic capability for the patency of LPV,SMV,and PV continuity.Part Ⅱ Evaluation of CDUS and MDCTP imaging in children with cavernous transformation of the portal vein after Rex shuntObjectivesThis study was aimed at exploring the imaging indicators related to prognosis,and to summarize the imaging features after Rex shunt and the advantages and disadvantages of CDUS and MDCTP techniques in postoperative evaluation.At the same time,CDUS was used to compare the surgical effect of classical Rex shunt and modified Rex transposition to achieve the best choice.MethodsForty-seven children with CTPV received Rex shunt in our hospital from March 2010 to March 2019 were included in this study.We retrospectively reviewed the clinical characteristics before and after the operation.The clinical information included the symptoms related to portal hypertension such as hematemesis and black stool,the results of laboratory examination(platelet count),and endoscopic findings(the degree and grade of gastroesophageal varices).The imaging data included the patency of bypass vessels and left portal vein,changes in diameter and hemodynamic,as well as the size of the liver and spleen.Six months after the operation,children were divided into the patent bypass group(group A)and the blocked bypass group(group B)according to the patency of bypass vessels.The correlation between the bypass vessel patency,the change of bypass vessel diameter,and the prognosis was analyzed.Meanwhile,the postoperative imaging features of CDUS and MDCTP were observed,and the diagnostic efficacy of CDUS and MDCTP on the bypass vessel patency and the consistency of the diagnosis results were compared.CDUS was used to comprehensively evaluate the diameter and hemodynamic changes of related vessels and organs after the Rex shunt,the relevance between these changes and bypass patency as well as the different surgical prognosis of classical Rex shunt(RB)and modified Rex transposition(RT).Results1.42 of 47 children with CTPV who underwent Rex shunt had patent bypass vessels(Group A).The degree of gastroesophageal varices was improved significantly than that in the blocked bypass group(Group B)(P<0.001),and the postoperative platelet count increased significantly(P<0.001).The platelet count remained unchanged at 6 months after operation in Group B(P>0.05).2.The caliber of the bypass vein was gradually widened in 57.1%of children(24/42)within 6 months after the operation.The improvement of gastroesophageal varices,the increase of platelet count,and the decrease of portal vein pressure in the widening group were significantly higher than those in the non-widening group(P<0.05)。The diameter was significantly larger than that in the non-widening group(P=0.038),but there was no significant difference in blood flow velocity between the two groups(P=0.613).The diameter and blood flow velocity of bypass vessels were 0.59±0.09cm and 13.79±2.74cm/s respectively at 6 months postoperatively.Kendall’s tau-b correlation analysis indicated that there was a weak relevance between the diameter and flow velocity of the bypass vessel(Kendall’s tau-b=0.272,P=0.013).3.The patent bypass appeared in CDUS with the hepatopetal venous flow on color and Doppler spectra.The flow direction of the proximal segment of the left portal vein was reversed and toward the right portal vein.The thrombosed bypass was seen on CDUS as a tubular structure filled with hypoechoic material with the absence of a Doppler signal.The flow in the proximal left portal vein changed to the normal direction seen before surgery.Postoperative MDCTP imaging depicted that a successful bypass was unobstructed with rich contrast filled well in the lumen.The occluded bypass may be demonstrated as a low-density cord on MDCTP with no contrast within its dilated lumen.Also,tiny clots could be seen in the portal vein,splenic vein,superior and inferior mesenteric vein,or branches with visible strip or sheet-like low-density filling defects.4.The success rate of bypass patency on CDUS(95.7%)was significantly higher than that on MDCTP(80.9%)(P=0.025).The McNemar test(P=1.000>0.05)and Kappa consistency analysis(Kappa=0.843,P<0.001)of the diagnostic results indicated that the outcomes obtained were consistent between the two methods.5.The oblique diameter of the right hepatic lobe,the upper and lower diameter of the left hepatic lobe,and the diameter of the left portal vein and bypass vessels increased significantly after the operation(P<0.05).Those changes in the patent bypass group were significantly higher than those in the blocked bypass group(P<0.05)。Whereas,there was no significant change in the anastomotic stoma,the residual diameter of the liver,and spleen postoperatively(P>0.05).While the bypass diameter was wider in the blocked bypass group during the operation(P<0.05).6.There was no significant difference in the incidence of bypass thrombosis,the widening of bypass vessel and the increase of the oblique diameter of the right hepatic lobe and the upper and lower diameter of the left hepatic lobe between the two groups(P>0.05).However,the diameter increase of the left portal vein and the bypass vessel in the RB group were significantly higher than those in the RT group(P<0.05).Conclusion1.The patency of the bypass vessel was consistent with the changes in platelet count and gastroesophageal varices before and after surgery.The patency of the bypass vessel provides reliable indicators for surgical effect.2.In addition to the patency of the bypass vessels,the gradual widening of bypass vessels within 6 months after the operation was a related index of good prognosis.The diameter of the bypass vessel had a weak correlation with blood flow velocity,and the analysis of the relationship between the bypass flow change and prognosis was of little significance.3.CDUS can serially monitor the hemodynamic changes of portal circulation including bypass vessels,and postoperative reversal of the blood flow direction of the proximal left portal vein is an important manifestation of patent bypass vessels.MDCTP can illustrate the involved parts of tiny obstruction more comprehensively and clearly.4.The display rate of bypass vascular patency performed by CDUS was significantly higher than by MDCTP,but the diagnostic results were highly consistent between the two approaches.CDUS should be the initial imaging modality for evaluating bypass vascular patency.5.Changes in the oblique diameter of the right hepatic lobe,the upper and lower diameters of the left hepatic lobe,and the diameter of the left portal vein or bypass vessel can reflect the effect of Rex shunt surgery earlier.The diameter of the liver and related blood vessels no longer increased after thrombosis.The increase level in the oblique diameter of the right hepatic lobe,the upper and lower diameters of the left hepatic lobe,and the diameter of the left portal vein and the bypass vessels can indirectly reflect the surgical effect.The higher the increase of related diameter,the better the prognosis.However,a wider-caliber autologous blood vessel is not necessarily the best surgical bypass option.6.Classical Rex shunt is still the most ideal surgical method in our center,and modified Rex transposition is also an effective alternative for the treatment of CTPV in children.Part Ⅲ The application of CDUS in the prognosis evaluation of new umbilical vein recanalization Rex shuntObjectivesTo explore CDUS findings in evaluating the prognosis of new umbilical vein recanalization Rex shunt,and to assess the surgical effect of the new shunt surgery by comparing with the traditional Rex shunt.Methods15 children who underwent new Rex shunt from May 2016 to March 2019 were taken as observation group(UV group),with the recanalized umbilical vein as bypass entrance,while 32 children who underwent traditional Rex operation from March 2010 to March 2019 were selected as the control group(LPV group),with the left portal vein as bypass entrance.CDUS was used to examine the related blood vessels and organs of children in the UV group,and the postoperative effect was evaluated in comparison with the LPV group.The diameters of liver and spleen(the oblique diameter of the right hepatic lobe,the anteroposterior diameter of the left hepatic lobe,the upper and lower diameter of the left hepatic lobe,the thickness of spleen,the maximum length of the spleen),the left portal vein,bypass vessels,and anastomosis were measured and calculated,and the blood flow status of the left portal vein,bypass vessels and anastomosis were observed.At the same time,the changes of clinical characteristics such as the incidence of rebleeding,the remission of gastroesophageal varices,the elevated level of platelet,and the decrease of portal pressure were compared and analyzed between the two groups by collecting endoscopic and laboratory findings.Results1.The 7-day bypass patency rate of 60%in the UV group was significantly lower than that of the LPV group(87.5%)postoperatively(P=0.032).After short-term anticoagulation,the total bypass patency rate of the UV group was 86.7%and that of the LPV group was 90.6%with no significant difference(P=0.642)at 6 months after surgery.According to the intraoperative UV diameter and the bypass thrombosis in 7 days after surgery,the ROC curve illustrated that the area under the ROC curve was 0.954,and the best cut-off value was>7.5.2.There was no significant difference in the diameter of bypass vessels and SMV anastomoses between the UV group and the LPV group(P>0.05).However,the LPV/UV anastomotic diameter of the UV group was significantly higher than that of the LPV group(P<0.001),and there was no significant difference in blood flow velocity of LPV/UV anastomosis between the two groups(P>0.05).The increase in the diameter of the left portal vein,the oblique diameter of the right hepatic lobe,and the upper and lower diameter of the left hepatic lobe in the UV group was higher than that in the LPV group(P<0.05),but there was no significant change in the diameter of the bypass vessels,the anastomosis and remaining diameters of the liver and spleen(P>0.05).3.The remission grade of gastroesophageal varices and the elevated level of platelet in the UV group were significantly higher than those in the LPV group(P=0.027,P=0.049),but there was no significant difference in the incidence of rebleeding and the reduction in portal pressure between the two groups(P>0.05).Conclusion1.Thrombus occurred more easily in the UV group than in the LPV group 7 days postoperatively,but the anticoagulant recanalization effect was better than that of the LPV group.There was no significant difference in the total patency rate between the two groups at 6 months after surgery.If the intraoperative umbilical vein was mechanically dilated more than 7.5mm in the UV group,the bypass blood vessel was prone to be obstructed in the early stage.2.The UV group had more hepatopetal flow than the LPV group,so the diameter of the left portal vein in the UV group widened more obviously.The increase of intrahepatic blood perfusion promoted the growth of the liver,which led to a more significant increase in liver diameter(oblique diameter of the right hepatic lobe and upper and lower diameter of the left hepatic lobe)than that in LPV group.3.The improvement of portal hypertension in the UV group was better than that in the LPV group,which was consistent with the diameter changes of the left portal vein and liver.Recanalized umbilical vein is an improved and valuable entrance for bypass.CDUS has been utilized as the primary modality in routine postoperative follow-up to predict the prognosis of umbilical vein recanalization Rex shunt,therefore providing an effective reference for the clinic.Conclusion1.Most of the CTPV in children involved the main portal vein as well as its left and right branches,and some of them were complicated with congenital malformations.MDCTP should be preferred for preoperative evaluation of the Rex shunt because it provided the greater diagnostic capability for the patency of LPV,SMV,and PV continuity.Additionally,it provided detailed anatomical information of the extrahepatic branches and all collateral vessels.2.The patency of the bypass vessel provides reliable indicators for surgical effect.The display rate of bypass vascular patency performed by CDUS was significantly higher than by MDCTP.Besides,CDUS can serially monitor the hemodynamic changes of portal circulation,and postoperative reversal of the blood flow direction of the proximal left portal vein is an important manifestation of patent bypass vessels.CDUS should be the initial imaging modality for evaluating bypass vascular patency postoperatively.Classical Rex shunt is still the most ideal surgical method in our center.3.Early bypass vascular thrombosis was likely to occur if the operative diameter of the umbilical vein was dilated more than 7.5mm.However,there was no significant difference in the total patency rate between the two shunt surgery.The wider diameter of distal anastomosis after umbilical vein recanalization Rex shunt promoted a better clinical outcome than the traditional Rex shunt.Recanalized umbilical vein is an improved and valuable entrance for bypass.CDUS should be utilized as the primary modality in routine postoperative follow-up to predict the prognosis of umbilical vein recanalization Rex shunt. |
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