REVIEW Non-invasive evaluation of liver cirrhosis using ultrasound N. Goyal a, *, N. Jain a , V. Rachapalli a , D.L. Cochlin a , M. Robinson b a Department of Radiology, University Hospital of Wales, Cardiff, UK, and b Department of Radiology, Royal Gwent Hospital, Newport, Wales, UK Received 2 March 2009; received in revised form 26 May 2009; accepted 27 May 2009 Ultrasound (US) is essential in both assessment of the potentially cirrhotic liver and surveillance of selected patients with chronic hepatitis as liver biopsy can be misleading or inaccurate in up to 25% of cases. Various techniques are already in routine use, such as grey-scale imaging, Doppler US, and contrast-enhanced US (CEUS), while newer techniques such as elastography and hepatic vein transit time (HVTT) have the potential to exclude patients without significant fibrosis or cirrhosis; however, they are operator dependent and require specific software. Grey-scale imaging may demonstrate changes, such as volume redistribution, capsule nodularity, parenchymal nodularity, and echotexture changes. The Doppler findings in the hepatic and portal veins, hepatic artery, and varices allow assessment of liver cirrhosis. However, the operator needs to be aware of limitations of these techniques. Low mechanical index CEUS plays an important role in the assessment of complications of cirrhosis, such as hepatocellular carcinoma and portal vein thrombus. Optimized US technique is crucial for accurate diagnosis of the cirrhotic liver and its complications. ª 2009 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved. Introduction Cirrhosis of the liver is a chronic, diffuse, and progressive condition characterized by fibrosis and the conversion of normal liver architecture into structurally abnormal nodules. 1 The progression of liver injury to cirrhosis may occur over weeks to years. The nature of injury resulting in liver cirrho- sis is diverse and some causes are listed in Table 1. Cirrhosis poses a difficult challenge for manage- ment, while the disease’s prevention, detection, and therapy engender major health costs. In patients with chronic liver disease, the stage of fibrosis is an important factor as it helps decide the therapeutic options and predict the prognosis. Histological examination of percutaneous biopsy specimens is considered the reference standard for assessment of severity of fibrosis and presence of cirrhosis. However, this biopsy only represents 1/50,000 of the entire liver. 2 Although a percutane- ous liver biopsy is relatively safe, it is still associated with a risk of complications, patient discomfort, and a high cost. 2e5 Liver biopsy may yield false-neg- ative results in up to 30% of cases. 2,4,6 Moreover, biopsy is invasive and cannot be used repeatedly in follow-up. Therefore, there is a need for a simple, reliable, non-invasive technique to assess the liver fibrosis stage and cirrhosis. 7 Non-invasive biochem- ical tests have also been suggested for monitoring chronic liver disease using the platelet count, 8e10 aspartate aminotransferase (AST)/alanine amino- transferase (ALT) ratio, 9,10 and serum hyaluronan and type III procollagen amino-terminal peptide. 11 Diagnostic imaging offers diverse methods for use in the non-invasive evaluation of the liver, as well as in interventional techniques; the latter may be used to treat such complications as portal hypertension and neoplasia. Ultrasound (US) is a non-invasive, inexpensive, and repeatable tech- nique for diagnosis of focal and diffuse parenchy- mal disease of the liver. It is used in combination * Guarantor and correspondent: N. Goyal, Department of Radiology, University Hospital of Wales, Cardiff CF14 4XW, UK. Tel: þ44 29 2074 3030; fax: þ44 29 2074 3029. E-mail address: [email protected](N. Goyal). 0009-9260/$ - see front matter ª 2009 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.crad.2009.05.010 Clinical Radiology (2009) 64, 1056e1066
Transcript
Clinical Radiology (2009) 64, 1056e1066
REVIEW
Non-invasive evaluation of liver cirrhosis usingultrasound
N. Goyala,*, N. Jaina, V. Rachapallia, D.L. Cochlina, M. Robinsonb
aDepartment of Radiology, University Hospital of Wales, Cardiff, UK, and bDepartment of Radiology,Royal Gwent Hospital, Newport, Wales, UK
Received 2 March 2009; received in revised form 26 May 2009; accepted 27 May 2009
Ultrasound (US) is essential in both assessment of the potentially cirrhotic liver and surveillance of selected patients
with chronic hepatitis as liver biopsy can be misleading or inaccurate in up to 25% of cases. Various techniques arealready in routine use, such as grey-scale imaging, Doppler US, and contrast-enhanced US (CEUS), while newertechniques such as elastography and hepatic vein transit time (HVTT) have the potential to exclude patients withoutsignificant fibrosis or cirrhosis; however, they are operator dependent and require specific software. Grey-scale imagingmay demonstrate changes, such as volume redistribution, capsule nodularity, parenchymal nodularity, and echotexturechanges. The Doppler findings in the hepatic and portal veins, hepatic artery, and varices allow assessment of livercirrhosis. However, the operator needs to be aware of limitations of these techniques. Low mechanical index CEUSplays an important role in the assessment of complications of cirrhosis, such as hepatocellular carcinoma and portalvein thrombus. Optimized US technique is crucial for accurate diagnosis of the cirrhotic liver and its complications.ª 2009 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.
Introduction
Cirrhosis of the liver is a chronic, diffuse, andprogressive condition characterized by fibrosis andthe conversion of normal liver architecture intostructurally abnormal nodules.1 The progression ofliver injury to cirrhosis may occur over weeks toyears. The nature of injury resulting in liver cirrho-sis is diverse and some causes are listed in Table 1.
Cirrhosis poses a difficult challenge for manage-ment, while the disease’s prevention, detection,and therapy engender major health costs. Inpatients with chronic liver disease, the stage offibrosis is an important factor as it helps decide thetherapeutic options and predict the prognosis.Histological examination of percutaneous biopsyspecimens is considered the reference standardfor assessment of severity of fibrosis and presence
* Guarantor and correspondent: N. Goyal, Department ofRadiology, University Hospital of Wales, Cardiff CF14 4XW, UK.Tel: þ44 29 2074 3030; fax: þ44 29 2074 3029.
0009-9260/$ - see front matter ª 2009 The Royal College of Radioldoi:10.1016/j.crad.2009.05.010
of cirrhosis. However, this biopsy only represents1/50,000 of the entire liver.2 Although a percutane-ous liver biopsy is relatively safe, it is still associatedwith a risk of complications, patient discomfort,and a high cost.2e5 Liver biopsy may yield false-neg-ative results in up to 30% of cases.2,4,6 Moreover,biopsy is invasive and cannot be used repeatedlyin follow-up. Therefore, there is a need for a simple,reliable, non-invasive technique to assess the liverfibrosis stage and cirrhosis.7 Non-invasive biochem-ical tests have also been suggested for monitoringchronic liver disease using the platelet count,8e10
aspartate aminotransferase (AST)/alanine amino-transferase (ALT) ratio,9,10 and serum hyaluronanand type III procollagen amino-terminal peptide.11
Diagnostic imaging offers diverse methods foruse in the non-invasive evaluation of the liver, aswell as in interventional techniques; the lattermay be used to treat such complications as portalhypertension and neoplasia. Ultrasound (US) isa non-invasive, inexpensive, and repeatable tech-nique for diagnosis of focal and diffuse parenchy-mal disease of the liver. It is used in combination
ogists. Published by Elsevier Ltd. All rights reserved.
Most common causes� Hepatitis C� Alcoholic liver disease� Hepatitis C plus alcoholic liver disease� Cryptogenic causes� Hepatitis B, which may be coincident with hepatitis D
with serum alpha fetoprotein as the most impor-tant and valuable diagnostic tool for detectinghepatocellular carcinoma (HCC) during the follow-up of patients with viral hepatitis and otherselected cirrhotics.12,13
Figure 1 US image of a patient with cirrhosis. Note theirregular liver surface (small arrows) and a 2.3 cm hypo-echoic lesion in the left lobe of liver (large arrow). Thiswas proven to be a HCC on biopsy.
Role of US
Various factors, such as liver size, the bluntness ofthe liver edge, the coarseness of the liver paren-chyma, nodularity of the liver surface, the size ofthe lymph nodes around the hepatic artery, theirregularity and narrowness of the inferior venacava, portal vein velocity, and spleen size7,14e18
have been suggested for US evaluation of chronicliver disease. However, the conventional definitionof the fibrosis stage of the liver based on evalua-tion of these US factors is deficient and lacksprecision and consistency. Furthermore, thesefindings are equipment dependent.18 Indeed, ear-lier reports demonstrated no consistent correla-tion between the grey-scale US findings and thehistological findings and, therefore, claimed thatgrey-scale US was unreliable for grading and stag-ing the degree of liver damage.19 However, recentadvances in US technology have improved the diag-nostic accuracy for fibrosis in patients with chronicliver disease. We review the role of various UStechniques used in the diagnosis and assessmentof liver cirrhosis, including grey-scale imaging,Doppler US, contrast-enhanced US (CEUS), hepatic
vein transit time (HVTT) and elastography, andsuggest a scheme for evaluating patients with cir-rhosis with US in routine practice.
Grey-scale imaging
The liver surface has been most commonly used asa sole indicator for the diagnosis of cirrhosis usingconventional US.15,20e22 Liver surface nodularityreflects the presence of regenerative nodules andfibrous septa. Cirrhosis is divided into micro andmacronodular cirrhosis. In micronodular cirrhosis,all abnormal nodules are less than 3 mm in size.1
It is not possible to detect micronodular cirrhosiswith standard abdominal probes, whereas thelarger nodules of macronodular disease readilygive recognizable surface nodularity (Fig. 1). Ithas been reported that high-frequency transducerscan obtain satisfactory results for diagnosis of livercirrhosis22 (Fig. 2) whereas low-frequency US is notso reliable.23 Gaiani et al.15 confirmed that thepresence of cirrhosis may be underestimatedwhen based on a single parameter. The finding isconsidered positive if instead of a straight and reg-ular hyperechoic line, the liver surface appears asa dotted or irregular line and/or the liver paren-chyma shows areas with different echogenicity.6
Both the right and left lobes of the liver shouldbe assessed as changes may be more readily appar-ent in one side only. Grey-scale imaging may alsodemonstrate a paucity of peripheral hepatic ves-sels, accentuated echogenic wall of the portal
Figure 2 Comparison of low (a) and high-resolution (b and c) US in demonstrating irregular liver surface. Changesare most marked in the right lobe (c). Also note the areas of different echogenicity in the underlying liver.
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vein, and regenerating nodules with displacementof adjacent vessels.24
Cirrhosis results in a reduction in volume of theright lobe of liver with relative enlargement of thecaudate lobe.25 Harbin et al.26 originally measuredthe ratio of the transverse width of the caudatelobe, to the transverse width of the right lobe ofthe liver. Caudate lobe hypertrophy is defined asa ratio of greater than 0.6 between the transversediameter of the caudate lobe and the transversediameter of the right lobe6 (Fig. 3). Using this tech-nique, cirrhosis could be correctly diagnosed witha sensitivity of 84%, a specificity of 100%, and a diag-nostic accuracy of 94%. Other studies have foundsimilar results.27,28 Hess et al.29 used the ratio ofthe multidimensional caudate index to thetransverse diameter of right lobe and found itsuperior to using the transverse diameter of caudatelobe alone with a specificity of 95% and sensitivity of94.7%.
Cirrhosis with portal hypertension causes conges-tive splenomegaly. A craniocaudal measurement of
Figure 3 Longitudinal scan of the liver demonstratingthe hypertrophied caudate lobe (asterisk).
11e13 cm is frequently used as the upper limit ofnormal for splenic size. However, because of widevariations in shape, no consistent correlation hasbeen recognized between the spleen’s length andits overall volume. Therefore, an actual measure-ment is useful for the hepatologist, rather thana statement of normal or enlarged. Various studieshave shown that US is a non-invasive, sensitive,and specific technique for the evaluation of spleensize, which is a good marker for presence of portalhypertension with liver cirrhosis, especially whencombined with Doppler assessment of the portalvein.30e32
Ascites is a common problem in patients withcirrhosis. US is a sensitive technique and candetect small volumes of fluid (Fig. 4). Various stud-ies have demonstrated that gallbladder wall thick-ening was significantly more frequent in patientswith cirrhotic ascites than in patients with non-cirrhotic ascites.33e37
Figure 4 Minimal ascites is seen in the hepatorenalpouch (arrow). This small amount of ascites will not bedetectable clinically; US enables early detection.
Non-invasive evaluation of liver cirrhosis 1059
Hepatorenal syndrome is the development ofrenal failure in patients with advanced chronicliver disease, occasionally fulminant hepatitis,who often have portal hypertension and ascites.Hepatorenal syndrome is the most serious circula-tory renal dysfunction in cirrhosis.38 It occurs asa result of liver failure and has a very poor progno-sis. It occurs in up to 15% of patients withascites.39,40 Besides a non-specific finding of anechogenic kidney in comparison to the liver(Fig. 5), all patients with hepatorenal syndromehave an elevated renal resistive index (RI¼ peaksystolic velocity e end diastolic velocity/peak sys-tolic velocity) values (mean RI¼ 0.79� 0.06).41
These blood flow alterations are very early signs,which can usually be detected long before acuterenal failure (ARF) is clinically evident. Early de-tection and subsequent monitoring of increasedparenchymal RI values in cirrhotic patients permitidentification of patients at a high risk of develop-ing ARF and hepatorenal syndrome.42 Hepato-pathic patients with RI >0.7 face a 26-foldgreater risk of developing hepatorenal syndromethan hepatopathic patients with RI �0.7. Afterliver transplant, renal RI values are rapidly re-duced despite unvaried serum creatinine levels.Pre-transplant RI values >0.7 correlate with higherpost-transplant morbidity, and persistent post-transplant RI >0.7 is a negative prognosticfinding.43e46
Doppler US
Cirrhosis and portal hypertension may change theflow profile of the liver vasculature.47e49 DopplerUS can provide important information on the
Figure 5 Hepatorenal syndrome showing hyperechoickidney and massive ascites.
haemodynamics of the portal venous system, thehepatic artery, and the hepatic veins.
The diameter of a normal portal vein does notexceed 13 mm in quiet respiration and an increasein diameter by 20e100% from quiet respiration todeep inspiration, should be normally seen. Portalflow is hepatopetal (i.e., flow in the portal veinand hepatic artery are both in same directionand towards the liver) throughout the entire car-diac cycle; with a mean flow velocity of15e18 cm/s. Portal flow velocity varies with car-diac activity and respiration, giving the portalwaveform an undulating appearance. In cases ofportal hypertension, portal vein diameter may ex-ceed 13 mm. With increasing portal pressure, theportal flow velocity decreases and fluctuations dis-appear with flow becoming continuous; flow maybecome biphasic or hepatofugal (Fig. 6). Iwaoet al.47 found portal venous velocity to be signifi-cantly lower in patients with cirrhosis and oeso-phageal varices (11� 2.4 cm/s versus15.9� 2.8 cm/s in controls). In another study, por-tal venous velocity was also significantly lower inpaediatric patients with advanced cirrhosis(15.1� 4.2 cm/s versus 31� 1.4 cm/s in con-trols).50 A significantly lower mean portal venousvelocity was noted in cirrhotic patients(13� 3.2 cm/s versus 19.6� 2.6 cm/s in controls)by Zironi et al.51 and 15 cm/s was considered asthe best cut-off value in the detection of portal hy-pertension, showing a sensitivity and specificity of88% and 96%, respectively. A narrow portal veinand a prominent hepatic artery are commonly
Figure 6 Colour Doppler image demonstrating hepato-fugal flow in the portal vein (large arrow) and hepatope-tal flow in the hepatic artery (small arrow).
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associated grey-scale US findings when flow is hep-atofugal in the main portal vein.
The normal hepatic artery has a low-resistanceDoppler flow profile with an RI of about 0.6 to0.7.52 During systole, the velocity is approximately30e40 cm/s; while during diastole it normallyslows down to 10e15 cm/s. In portal hypertension,hepatic artery flow may increase substantiallycompensating for the diminished portal vein flow.The arterio-portal velocity ratio was significantlyhigher in patients with cirrhosis than in controls(p< 0.0005). Using a cut-off value of >3 the ratiohad a sensitivity and specificity of 78% and 100%,respectively.50 The pulsatility index (PI¼ peak sys-tolic velocity e mean velocity/peak systolic veloc-ity) and RI have been shown to be higher incirrhosis patients.47,53,54
The hepatic veins are straight, anechoic, tubu-lar structures that converge towards the inferiorvena cava approximately 1 cm below its conflu-ence with the right atrium. The normal hepaticvein waveform is triphasic as a result of transmit-ted cardiac activity. Variations in flow are seenduring the respiratory cycle with flow increasingduring inspiration and decreasing during expira-tion.55 Measurements should be taken in the rightand middle hepatic veins to avoid artefact fromtransmitted cardiac movement seen in the left he-patic vein.
In cirrhotic patients, two alterations of hepaticvein flow profile may be observed. There is re-gional flow acceleration resulting from focal com-pression by regenerative nodules and dampeningof the pulsatile flow profile secondary to non-compliance caused by fibrous tissue. Although lossof reverse flow component may indicate cirrhosis,this abnormal waveform can occur in diseases suchas BuddeChiari syndrome, steatosis, and in diffusehepatic metastases. Moreover, deep inspiration,obesity, or ascites are factors that may influence
Figure 7 Grey-scale imaging showing an enlarged spleenimaging of the same patient confirms the presence of varice
the hepatic flow profile.49,56e62 Ohta et al.59 madean important observation that cirrhotic patientswith flattening of the flow profile in the right he-patic vein had a very poor prognosis and diedwithin 2 years.
Studies have found that apart from hepatic veinprofile (HVP), Doppler-derived indices, such asportal vein diameter, portal vein velocity, andhepatic arterial resistance index used for theassessment of severity in chronic liver disease aredifficult to reproduce reliably and, therefore, havea limited clinical role in the non-invasive assess-ment of hepatic fibrosis or inflammation.63 Spleensize and abnormal HVP are useful predictors ofchronic liver disease and cirrhosis, and both canbe measured reliably and reproducibly.64
Portosystemic venous collaterals (Fig. 7) areevidence of portal hypertension except when col-laterals develop in isolated splenic or splenome-senteric obstruction in the setting of neoplasm,pancreatitis, or previous surgery. More than 20 col-lateral pathways have been described, with themost common being the gastro-oesophageal, para-umbilical, splenorenal, and inferior mesenteric.Colour Doppler US is a useful non-invasive methodfor evaluating the risk of oesophageal varicealbleeding in patients with liver cirrhosis.65,66
Portal vein occlusion due to clots may exhibitvariable echogenicity on B-mode imaging, tendingto be hypoechoic if recently formed (Fig. 8). Col-our Doppler US is very useful for the demonstrationof the nature of portal vein thrombosis. Failure toidentify the portal vein strongly suggests occlu-sion. Colour Doppler US distinguishes betweenportal vein tumour and thrombus through thedetection of flow within the occluded vein withpulsatile arterial flow in cases of portal veintumour extension.
Several limitations of Doppler assessment exist.It is generally agreed that the portal flow velocity
, dilated splenic vein and splenorenal varices. Dopplers.
Figure 8 US showing thrombus within the portal vein(arrow) in a patient with HCC (markers).
Non-invasive evaluation of liver cirrhosis 1061
is decreased in cirrhotic patients. However, theabsolute value of portal flow velocity is known tovary considerably in both healthy subjects andcirrhotic patients.55 Inter-observer variability,differences in methodology and equipment used,and errors in Doppler can all explain variations inportal venous velocity reported in the litera-ture.51,67e69 Furthermore, portal blood flow isinfluenced by numerous factors, such as changesin the body position, phase of respiration, timingof meals, exercise, and cardiac output.70e74 Rever-sal of flow is not a pathognomonic feature ofcirrhosis and is also seen in patients with veno-occlusive disease and spontaneous or surgicallycreated portosystemic shunts.75e77 Besides, portalflow may be unaltered in cirrhotic patients due toa combination of high inflow from the splanchnicorgans and increased resistance within the liver.78
High RI of the hepatic artery is seen in patientswith end-stage liver disease, particularly inchildren with severe cirrhosis secondary to biliaryatresia.79 However, hepatic artery flow remainsnormal in most patients.48 Abnormal hepatic veinflow profiles are seen in patients with cirrhosis,although dampening or flattening of the flowprofile may be seen in patients with BuddeChiarisyndrome, metastases and ascites and may bea normal variant.49,56e62
CEUS
Microbubble contrast medium is a useful adjunct tothe US study in a patient with cirrhosis. CEUS can beused to characterize focal liver lesions with 96.6%accuracy, a value higher than US, Doppler US, AFP
levels, combined US and alpha fetoprotein (AFP)levels, and combined US and Doppler US.80e82
CEUS may be used to characterise focal liver lesionsdetected during HCC surveillance of cirrhoticpatients. Arterial phase vascular intensity and pat-tern of CEUS are highly accurate for the diagnosisof small (1e2 cm) HCC in liver cirrhosis. On CEUS,arterial phase hypervascularity without a haeman-gioma pattern alone may be sufficient for diagnosisof small HCC. Infrequent iso/hypovascular HCC mayerroneously suggest a regenerative or dysplasticnodule necessitating biopsy or close follow-up.83e85
HVTT is highly sensitive for cirrhosis and can beused to predict disease severity in patients withchronic liver disease.86,87 Analysis of the time ofonset of US contrast enhancement of the hepaticvein appears to be a potentially useful non-inva-sive supplement to conventional US and Dopplerin the follow-up of patients with chronic diffuseliver disease.88 A decreasing HVTT is observedwith increasing severity of liver disease. This isthought to be secondary to arteriovenous shuntingand arterialisation of capillary beds in the liver.A recent study has shown that calculation of intra-hepatic circulatory time (IHCT) using a third-gen-eration microbubble agent and contrast harmonicimaging can differentiate mild fibrosis from moresevere degrees of fibrosis in patients with hepatitisC virus.89 US microbubble contrast agent can beused to assess hepatitis C virus-related liverdisease with clear differentiation between mildhepatitis and cirrhosis with significant differencesbetween these two groups.86
Staub et al.90 used a cut-off of 13 s for the tran-sit time and made the diagnosis of severe fibrosiswith a specificity of 78.57%, a sensitivity of78.95%, a positive predictive value of 78.33%,a negative predictive value of 83.33%, and a perfor-mance accuracy of 78.79%.
HVTT may complement liver biopsy and mayalso be a useful alternative for assessment of liverdisease in patients who have contraindications tobiopsy. However, HVTT is not widely used as not alloperators have found the results easy to reproduceand it may require specific software. Both trans-abdominal and endoscopic CEUS have also beendescribed for better delineation of the varices andshunts, but this is not widely used.91,92
Elastography: transient (fibroscan) andreal time
Transient elastography (TE) is a novel method withthe first clinical data using this technique pub-lished in 2002. It is performed with an US
1062 N. Goyal et al.
transducer probe mounted on the axis of a vibrator.A vibration transmitted from the vibrator towardthe tissue induces an elastic shear wave thatpropagates through the tissue. These propagationsare followed by pulse-echo US acquisitions andtheir velocity is measured, which is relateddirectly to tissue stiffness.93 The harder the tissue,the faster the shear wave propagates.94 TE is pain-less, rapid (less than 5 min), and easy to performat the bedside or in the outpatient clinic. The ex-amination is performed on a non-fasting patient.95
The results are immediately available and are op-erator-independent.96 The examination can beperformed by a nurse after a short learning curve(about 100 examinations).97 Several studies haveproved the reproducibility of TE.94,96 Besides beingreproducible and independent of the operator, TEexplores a volume of liver parenchyma, which isapproximately 100 times larger than the biopsyspecimen volume. Fibroscan is a promising non-in-vasive method for detection of cirrhosis in patientswith chronic liver disease with possible use in fol-low-up and management of these patients98 andpreliminary studies in human subjects have con-firmed the feasibility of these techniques for quan-titative assessment of hepatic fibrosis.99e101
Real-time elastography is a new method for themeasurement of tissue elasticity integrated in anUS machine (Hitachi EUB-8500 and EUB-900) and istechnically different from TE. Conventional USprobes compare and analyse echo signals beforeand under slight compression.102 However, tissueelasticity cannot be measured directly from re-flected US echoes and methods analysing the dis-placement of phases (e.g., cross-correlationmethod) have been investigated in previous stud-ies using the elastography principle.103e105 How-ever, these measurements were associated with
Figure 9 Grey-scale US image showing TIPS stent in situ. NUS confirms flow within the stent with subtle variations in t
strong aliasing. To overcome these restrictions,Hitachi Medical Systems developed real-time elas-tography based on the combined autocorrelationmethod and three-dimensional tissue model forthe determination of phase displacement in real-time without aliasing.106e108 In recent studies,researchers have evaluated real-time elastographyfor the characterisation and detection of focallesions in the breast, thyroid gland, and prostategland.102,109e111 Friedrich-Rust et al.100 haverecently shown RTE to be a useful non-invasivemethod for assessment of liver fibrosis. Elastogra-phy has the potential to be used as a screeningtool and may help avoid biopsy as a normal resulteffectively means patients are unlikely to have se-vere fibrosis or cirrhosis.
US-guided biopsy and evaluation oftransjugular intrahepatic portasystemicshunt (tips)
US facilitates biopsy of the liver under directvisualization when required and also allows tar-geted biopsy of liver lesions. Even in the absenceof major complications, US-guided liver biopsywith an automated needle has been shown to besafer, more comfortable, and only marginally moreexpensive than blind Trucut biopsy112 and obtainsgood histological material in most cases.113 US-guided biopsies have also been shown to be associ-ated with lower hospitalization rates from majorcomplications and thus may potentially decreasemorbidity and reduce costs.114e116
Doppler US may be used to assess patency anddirection of flow within the portal vein and in theTIPS117,118 (Fig. 9). The shunt should be evaluated
ote the hyperechoic walls of the stent (arrow). Dopplerhe waveform.
Table 2 Doppler assessment of TIPS.
Criteria indicating normal TIPS function
B Pulsatile flow directly shown within the stentB Peak systolic velocity in the shunt of at least
50e60 cm/s (range 90e120 cm/s), and similarthroughout the shunt
B Portal vein velocity is substantially greater than itspre-shunt value (minimum 30 cm/s; range 37e47 cm/s)
B Hepatopetal flow within portal trunk and splenic vein.
Abnormal Doppler parameters
B Continuous waveform of the flow within the stentB Variation (decrease or elevation) in shunt velocity
>50 cm/s compared with baseline value.B Hepatofugalor to-and-froportal and/or splenicveinflow
Non-invasive evaluation of liver cirrhosis 1063
within the first 24 h after the TIPS procedure notonly to assess patency, but also to establish baselineflow parameters. Regular follow-up is advisable toassess patency and stenosis. Normal and abnormalDoppler parameters are listed in Table 2.119
Conclusion
Optimized US technique is important for accuratediagnosis of the cirrhotic liver and its complica-tions. Grey-scale imaging, including high-resolu-tion US and Doppler US, should be routinelyapplied in the evaluation of such cases. HVTT and
Table 3 Suggested scheme for grey-scale and Dopplerimaging of liver cirrhosis.
Normal triphasic/biphasic/monophasic(also abnormal withsteatosis)
Portal veina (13 mm maximum)(little change in respiration inportal hypertension)
Size/flow direction
Varices or shunts
a If splenomegaly then splenic and portal veins maybelarger than normal.
TE are being increasingly used to diagnose thepresence or absence of cirrhosis and offer thepotential to stage liver fibrosis. A scheme that mayserve as an aide memoir for trainee radiologistswhile scanning patients with suspected cirrhosisor for follow-up of such patients is presented inTable 3.
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