cirrhosis is a global public health concern that results from chronic liver damage due to viral infection , alcohol abuse , autoimmune disease , and non - alcoholic steatohepatitis . in cirrhotic patients ,
the mortality rate of patients with initial episodes of variceal hemorrhage is up to 20% , and the recurrence rate of bleeding in survivors is high .
therefore , screening endoscopy for ev in all patients with cirrhosis is recommended in the current guidelines to identify patients who need prophylactic treatment .
however , at any given point in time , approximately 75% to 85% of cirrhotic patients undergoing endoscopy have no ev or only have mild ev , which do not need medical intervention .
therefore , all patients with cirrhosis undergoing periodic endoscopy might unnecessarily increase the burden for both the medical service and patients . nevertheless , endoscopy is invasive , uncomfortable , and requires anesthesia .
accordingly , in recent years , alternative ways to predict ev , such as those that use spleen length , child - pugh class , platelet count , portal vein diameter , elastography , or a combination of these indices , have been developed to reduce unnecessary endoscopy [ 814 ] .
however , these reported indices were various and the cut - off values of the same index were different ; therefore , the previous results are unreliable and further validation is necessary .
recently , contrast - enhanced ultrasonography ( ceus ) has been widely used in liver imaging , such as characterizing focal lesions .
compared with contrast - enhanced ct and contrast - enhanced mri , ceus is low cost , repeatable , safer , and can be controlled by operators in real - time during the measurements .
moreover , previous studies have demonstrated that hepatic dynamic ceus features are correlated with severity of chronic liver diseases ( cld ) , degree of liver fibrosis , and portal pressure . in patients with cirrhosis ,
however , the usefulness of liver dynamic ceus features for assessing the ev has not been evaluated . the present study aimed to investigate the usefulness of ceus in predicting esophageal varices ( ev ) and assessing high - risk ev in patients with hbv - related cirrhosis .
between oct 2014 and dec 2016 , consecutive patients with hbv - related cirrhosis who had undergone endoscopy and agreed to participate in this study were recruited .
the diagnosis of liver cirrhosis was based on liver biopsy according to the metavir scoring system .
patients had to meet the following inclusion criteria : ( 1 ) more than 18 years old ; ( 2 ) the interval between endoscopy and ceus imaging was less than 60 days ; and ( 3 ) hbsag - positive .
exclusion criteria were : ( 1 ) focal liver lesions ; ( 2 ) a history of ev ligation or endoscopic injection sclerotherapy ; ( 3 ) a use of vasoactive drugs within 2 weeks before the ceus measurements ; ( 4 ) portal vein thrombosis ; ( 5 ) cavernous transformation of portal vein ; ( 6 ) co - infection with hcv or hiv ; and ( 7 ) a history of severe heart disease .
this study was approved by the institutional review board of the first affiliated hospital of shihezi university school of medicine .
hi vision ascendus ( hitachi aloka medical , tokyo , japan ) with a c715 convex probe ( 15 mhz ) was used in this study .
a sonologist ( jun li ) with more than 10 years of experience in abdominal ultrasonography performed the ceus .
all of the participants fasted more than 8 h and were placed in the supine position with the right arm extended above the head .
conventional b - mode ultrasonography and doppler ultrasonography were performed on the right lobe of the liver before the ceus imaging in order to choose an appropriate cross - section that contained the hepatic artery , hepatic vein , and portal vein simultaneously .
injection of contrast agent was administered by a single researcher ( ting - ting du ) . a bolus injection of 2.4 ml contrast agent ( sonovue ; bracco s.p.a . ,
milan , italy ) was administered through a 20-gauge catheter at the left antecubital fossa , followed by a rapid injection of 5 ml of normal saline .
dynamic contrast harmonic imaging was recorded from 10 s before sonovue injection to 2 min after injection .
regions of interest ( rois ) were drawn on the hepatic artery , hepatic vein , portal vein , and liver parenchyma .
for the vessels , the rois were kept within the vascular structures , for the liver parenchyma , a roi of 200 mm was set approximately 5 cm to 8 cm in depth under the transducer and more than 3 cm under the capsule , as well as to avoid including any large vascular structures .
the motions in the video caused by breaths during the measurements were corrected by the motion - correction algorithms of the analysis software .
all the rois which been drawn in the videos were checked by 2 of the authors to ensure that a time - intensity curve could be computed accurately . in the analysis software ,
the intensity of the ceus image was expressed as grey - scale ( range , 0 to 255 ) .
the time - intensity curve can be also quantified and outputted in microsoft excel for ease of interpretation and further analysis .
the interface of the analysis software and corresponding time - intensity curves are shown in figure 2 .
the mean value of the first 10 s of the video ( before the contrast agent injection ) was defined as the baseline intensity .
hepatic artery arrival time ( haat ) , hepatic vein arrival time ( hvat ) , and portal vein arrival time ( pvat ) were defined as the interval between sonovue injection and when the signal intensity exceeded 10% of the baseline in the corresponding roi .
psi was the difference between the peak signal intensity in the liver parenchyma and baseline intensity ; moreover , ttp was defined as the time interval between injection and liver parenchyma peak time . to lessen the impact of variations in the blood circulation time , hv  ha ( hvat minus haat ) and pv  ha ( pvat minus haat ) were calculated .
the time from 10% to 90% of liver parenchyma peak signal intensity was expressed as the rise time .
ev was diagnosed according to the published criteria : grade 0 , no varices ; 1 , straight small varices ; 2 , beaded medium - sized varices ; and 3 , nodular , tortuous , and tumor - like large varices .
the grades 0 and 1 ev patients were defined as a low - bleeding - risk group and grades 2 and 3 patients were considered at a high - risk of ev bleeding .
data were presented as mean  standard deviation if they were normally distributed , or expressed as median ( interquartile range ) .
data were compared between groups using student t - test or  test , as appropriate .
the area under the receiver operating characteristic curve ( auroc ) was computed to explore the diagnostic performance of ceus features .
spss 17.0 software ( chicago , il ) and medcalc 12.7.0.0 software ( mariakerke , belgium ) were used in this study .
between oct 2014 and dec 2016 , consecutive patients with hbv - related cirrhosis who had undergone endoscopy and agreed to participate in this study were recruited .
the diagnosis of liver cirrhosis was based on liver biopsy according to the metavir scoring system .
patients had to meet the following inclusion criteria : ( 1 ) more than 18 years old ; ( 2 ) the interval between endoscopy and ceus imaging was less than 60 days ; and ( 3 ) hbsag - positive .
exclusion criteria were : ( 1 ) focal liver lesions ; ( 2 ) a history of ev ligation or endoscopic injection sclerotherapy ; ( 3 ) a use of vasoactive drugs within 2 weeks before the ceus measurements ; ( 4 ) portal vein thrombosis ; ( 5 ) cavernous transformation of portal vein ; ( 6 ) co - infection with hcv or hiv ; and ( 7 ) a history of severe heart disease .
this study was approved by the institutional review board of the first affiliated hospital of shihezi university school of medicine .
hi vision ascendus ( hitachi aloka medical , tokyo , japan ) with a c715 convex probe ( 15 mhz ) was used in this study .
a sonologist ( jun li ) with more than 10 years of experience in abdominal ultrasonography performed the ceus .
all of the participants fasted more than 8 h and were placed in the supine position with the right arm extended above the head .
conventional b - mode ultrasonography and doppler ultrasonography were performed on the right lobe of the liver before the ceus imaging in order to choose an appropriate cross - section that contained the hepatic artery , hepatic vein , and portal vein simultaneously .
injection of contrast agent was administered by a single researcher ( ting - ting du ) . a bolus injection of 2.4 ml contrast agent ( sonovue ; bracco s.p.a . ,
milan , italy ) was administered through a 20-gauge catheter at the left antecubital fossa , followed by a rapid injection of 5 ml of normal saline .
dynamic contrast harmonic imaging was recorded from 10 s before sonovue injection to 2 min after injection .
regions of interest ( rois ) were drawn on the hepatic artery , hepatic vein , portal vein , and liver parenchyma .
for the vessels , the rois were kept within the vascular structures , for the liver parenchyma , a roi of 200 mm was set approximately 5 cm to 8 cm in depth under the transducer and more than 3 cm under the capsule , as well as to avoid including any large vascular structures .
the motions in the video caused by breaths during the measurements were corrected by the motion - correction algorithms of the analysis software .
all the rois which been drawn in the videos were checked by 2 of the authors to ensure that a time - intensity curve could be computed accurately . in the analysis software ,
the intensity of the ceus image was expressed as grey - scale ( range , 0 to 255 ) .
the time - intensity curve can be also quantified and outputted in microsoft excel for ease of interpretation and further analysis .
the interface of the analysis software and corresponding time - intensity curves are shown in figure 2 .
the mean value of the first 10 s of the video ( before the contrast agent injection ) was defined as the baseline intensity .
hepatic artery arrival time ( haat ) , hepatic vein arrival time ( hvat ) , and portal vein arrival time ( pvat ) were defined as the interval between sonovue injection and when the signal intensity exceeded 10% of the baseline in the corresponding roi .
psi was the difference between the peak signal intensity in the liver parenchyma and baseline intensity ; moreover , ttp was defined as the time interval between injection and liver parenchyma peak time . to lessen the impact of variations in the blood circulation time , hv  ha ( hvat minus haat ) and pv  ha ( pvat minus haat ) were calculated .
the time from 10% to 90% of liver parenchyma peak signal intensity was expressed as the rise time .
ev was diagnosed according to the published criteria : grade 0 , no varices ; 1 , straight small varices ; 2 , beaded medium - sized varices ; and 3 , nodular , tortuous , and tumor - like large varices .
the grades 0 and 1 ev patients were defined as a low - bleeding - risk group and grades 2 and 3 patients were considered at a high - risk of ev bleeding .
data were presented as mean  standard deviation if they were normally distributed , or expressed as median ( interquartile range ) .
data were compared between groups using student t - test or  test , as appropriate .
the area under the receiver operating characteristic curve ( auroc ) was computed to explore the diagnostic performance of ceus features .
spss 17.0 software ( chicago , il ) and medcalc 12.7.0.0 software ( mariakerke , belgium ) were used in this study .
in this prospective study , ceus was performed on 63 eligible patients ; of them , 5 ( 7.9% ) participants were excluded because of poor respiratory cooperation ( n=3 , 4.8% ) , rib shadow ( n=1 , 1.6% ) , and a severely atrophic liver ( n=1 , 1.6% ) .
finally , 58 patients were included in the data analysis and their characteristics are shown in table 1 .
of the 58 patients , 18 patients ( 31.0% ) had no ev , and 12 ( 20.7% ) , 11 ( 19.0% ) , and 17 ( 29.3% ) patients had grade 1 , 2 , and 3 ev , respectively .
compared with the non - ev group , the hvat , hv  ha , and psi
were significantly decreased in the ev groups ( p<0.001 , p<0.001 , p=0.010 , respectively ) , and pv  ha increased significantly ( p=0.024 ) .
similar results were observed in the high - risk group compared with the low - risk group ( p<0.001 for hvat , p<0.001 for hv  ha , p=0.013 for psi , respectively ) .
furthermore , pvat increased significantly in the high - risk group compared with the low - risk group ( p=0.019 ) .
ha , and psi were negatively correlated with the grade of ev . on the contrary ,
roc curves were computed to evaluate the diagnostic performance of features with significant correlation with the grade of ev ( table 4 , figure 3 ) . for the assessment of the presence of ev and high - risk ev ,
for the diagnosis of the presence of ev , the auroc was 0.883 , and the optimal cut - off value of hv  ha was 8.2 seconds with a sensitivity of 85% and a specificity of 78% . for the diagnosis of high - risk ev , the auroc was 0.915 , and
the optimal cut - off value of hv  ha was 7.0 s with a sensitivity of 82% and a specificity of 90% . in this case , the false - positive and false - negative rates of hv  ha were relatively low ( table 5 ) . in pairwise comparison of the aurocs , for evaluating the presence of ev , the differences between features were not significant ; for the evaluation of high - risk ev , hv 
ha allowed better assessment of high - risk ev compared with hvat , pv  ha , and psi ( p=0.006 , p=0.009 , p=0.006 , respectively ) .
ceus is widely used in cld patients , such as in assessing the severity of liver fibrosis and ph , and theoretically , ceus features may correlate with ev . under this assumption
, we conducted a pilot study utilizing ceus to predict the presence of ev and high - risk ev to relieve the burden on patients and medical service providers by reducing unnecessary endoscopy .
this study focused on cirrhotic patients with hbv and showed that several ceus features were closely correlated with the grade of ev ; moreover , the hv 
hvat has been reported in previous studies to be useful for evaluating portal pressure and staging liver fibrosis , because the structure of intrahepatic vasculature is changed by fibrous tissue , leading to arteriovenous shunting , and to some extent , arteriovenous shunting and arterialization of the sinusoidal bed , which may elevate the portal pressure .
ev as a result of ph was developed to relieve the high portal pressure and help the obstructed portal venous system to bypass the liver and flow into the systemic circulation .
this study showed that the hvat was closely negatively correlated with the grade of ev ( r=0.589 , p<0.001 ) ; therefore , hvat can be a good indicator for predicting the presence of ev and assessing high - risk ev ( auroc : 0.838 and 0.840 ) , with the cut - off values of 22 s and 20.8 s , respectively .
however , hvat is vulnerable to patient individual circulation time , how the contrast agent is injected , and when the timer is started . in clinical practice , hvat is easy to perform but is less reliable than hv  ha .
ha index had been used in many studies to correct the differences of participants blood circulation time . as expected , the aurocs of hv  ha was larger than that of hvat ( 0.883 vs. 0.838 for assessing presence of ev and 0.915 vs. 0.840 for assessing high - risk ev ) .
in addition , this index seems to be more reliable than hvat and is also feasible as a clinical tool .
ha was significantly correlated with ev grade ( r=0.296 , p=0.024 ) , its performance was insufficient for assessing the presence of ev and high - risk ev ( auroc , 0.726 and 0.714 , respectively ) .
we hypothesized that this ceus feature would tend to reflect the blood content of the liver in the different stages of cld .
the liver is rich in blood , like a blood - pool ; however , fibrosis and regenerative nodules increase with the progression of cld ; therefore , the blood - pool space is reduced . in the ceus images , reduced content of microbubble - filled blood - pool produces a reduction in signal intensity . on the other hand , although not conclusive , hepatic arterial buffer response may decrease when the compensation of collateral circulation reaches a peak .
the aurocs of psi were 0.710 for assessing the presence of ev and 0.672 for evaluating the high - risk ev . compared with hv  ha , the diagnostic accuracy of pis was significantly lower ( p=0.006 ) .
ttp has been used to evaluate the severity of ph in cirrhosis , but its performance was unsatisfactory .
in addition , another study reported a disappointing result of rise time for assessing ph in patients with cirrhosis .
although spleen length and portal vein diameter are easy to measure , a systematic review showed that they are not accurate enough to predict ev .
serum tests are popular to use in diagnosing ev of liver cirrhosis , but the indexes , including apri , aar , fib-4 , lok , and forns scores , had low - to - moderate diagnostic accuracy in predicting ev in liver cirrhosis . on the other hand , ct was reported to diagnose ev in liver cirrhosis with high accuracy , but ct can not be used for patients with renal failure due to the adverse effect of radiocontrast agent .
in addition , ct has high cost , static imaging ( non - dynamitic ) , and radioactive by - effects .
in addition , mri   is not a dynamic imaging system , which was reported as  the robustness of pv flow measurement on only 1 slice at a specific time point  .
doppler indexes have been used to diagnose ev for many years , but the results are unsatisfactory even today .
liver stiffness measured by transient elastography showed a good correlation with the severity of ev , and this approach is simple and reproducible .
however , the cut - off values vary between studies ( range , 13.9 kpa to 21.5 kpa for predicting the presence of ev ) ; thus , it has not been used in clinical practice .
examined the lower esophagus by ceus directly and found the thickness of mucosa and submucosa was strongly correlated with the grade of ev , with an auroc of 0.987 for detecting large ev ( the criteria for ev grade were not provided ) .
this approach is direct and interesting , but has a few disadvantages : it can not detect the middle and upper esophagus , and it is vulnerable to overlying gastrointestinal gas ; in addition , the contraction of the lower esophageal sphincter in the resting state may squash the varicose esophageal veins .
included 25 control participants , and 9 , 13 , and 34 patients with small , medium , and large ev , respectively , but did not include cirrhotic patients without ev . to some extent , this proportion of patients may increase the diagnostic performance .
in addition , the number of participants was small and further studies are needed to confirm this approach .
compared with the above - mentioned techniques , intrahepatic transit time ( i.e. , hv  ha ) was accurate , easy to detect , widely studied , and directly and closely correlated with the distortion of hepatic vascular architecture that may lead to ph and ev . in this study , the interval between endoscopy and ceus imaging was limited to within 60 days . according to previous studies on noninvasive assessment of ev , a 180-day interval is considered acceptable .
good respiratory cooperation was needed in this ceus imaging process in order to avoid losing the target vessel , especially near the arrival time .
although participants had been briefly trained before the measurement , a 4.8% failure rate was still obtained . to the best to our knowledge ,
manual injection of the contrast agent was the common method in ceus imaging ; however , a mechanical device may be more accurate and feasible in clinical work .
second , all the ceus imaging data were analyzed by 1 researcher ; thus , reader variability may be a drawback of this study
. however , the process for ceus imaging analysis in this study was standardized and the results were computed automatically , thereby minimizing variability between different readers .
in conclusion , dynamic ceus may be used for the assessment of ev , and hv  ha is the best index in predicting ev . considering the results of previous studies , hv  ha may provide a comprehensive assessment for patients with cld in many aspects , such as the degree of fibrosis , the severity of ph , and the grade of ev . although dynamic ceus imaging may not replace endoscopy completely ,
this technique is helpful in evaluating whether patients with hbv - related cirrhosis , particularly those who present a high risk of ev , should undergo endoscopy .
 backgroundthe aim of this study was to investigate the usefulness of contrast - enhanced ultrasonography ( ceus ) in predicting of esophageal varices ( ev ) and assessing high - risk ev in patients with hepatitis b virus ( hbv)-related cirrhosis.material/methodspatients with hbv - related cirrhosis who had undergone endoscopy were prospectively recruited . 
 hepatic dynamic ceus was performed . 
 regions of interest ( roi ) were drawn on the hepatic artery , hepatic vein , portal vein , and liver parenchyma to measure the corresponding features , such as arrival times . 
 spearman s correlation analysis was used to determine the relations between several dynamic ceus features and the degree of ev . 
 receiver operating characteristics ( roc ) curves were constructed to investigate the diagnostic performance of ceus in assessing the presence of ev and high - risk ev.resultsfifty-eight patients ( 44 men ; mean age 51.3 years ) were included in this study . of these , 18 ( 31.0% ) , 12 ( 20.7% ) , 11 ( 19.0% ) , and 17 ( 29.3% ) of patients had grade 0 , 1 , 2 , and 3 ev , respectively . 
 grade 2 and grade 3 ev were considered high - risk ev . among the ceus features , the area under the roc curves of intrahepatic transit time ( hv  ha , i.e. , the difference between hepatic vein arrival time and hepatic artery arrival time ) both for assessment of the presence of ev and high - risk ev ( 0.883 and 0.915 , respectively ) were larger than the other indices . 
 hv  
 ha was negatively correlated with the grade of ev . 
 an hv  ha of under 8.2 s indicated the presence of ev and under 7 s indicated high - risk ev.conclusionsdynamic ceus imaging is useful in assessing the presence of ev and high - risk ev in patients with hbv - related cirrhosis . 