Shear Wave Elastography of the Spleen for Monitoring Transjugular Intrahepatic Portosystemic Shunt Function: A Pilot Study

Diagnostic value of conventional ultrasound and shear wave elastography in detecting transjugular intrahepatic portosystemic shunt dysfunction

BACKGROUND

Transjugular intrahepatic portosystemic shunt (TIPS) dysfunction can cause recurrent portal hypertension (PH)-related complications such as ascites and gastroesophageal variceal bleeding. Portography is invasive and costly limits its use as a screening modality.

PURPOSE

To assess the clinical value of conventional ultrasound in combination with point shear wave elastography (pSWE) to predict TIPS dysfunction.

MATERIAL AND METHODS

A total of 184 patients with cirrhosis scheduled for TIPS implantation were enrolled in this study and evaluated retrospectively. The splenoportal venous blood flow parameter, liver stiffness (LS), and spleen stiffness (SPS) were measured. Outcome measures included differences in portal vein velocity (PVV), splenic vein velocity (SPVV), LS, and SPS. The accuracy of change in PVV (ΔPVV), SPVV (ΔSPVV), and SPS (ΔSPS) to diagnose TIPS dysfunction was investigated.

RESULTS

TIPS dysfunction occurred in 28 of 184 patients (15.2%). Eighteen (64.3%) patients had shunt stenoses and 10 (35.7%) had shunt occlusion. Portal vein diameter (PVD), PVV, splenic vein diameter (SPVD), SPVV, LS, and SPS were not significantly different between the TIPS normal and TIPS dysfunction groups. Compared with the TIPS normal group, PVV and SPVV of the TIPS dysfunction group decreased significantly, whereas SPS increased significantly (P < 0.001). The values of areas under the receiver operating characteristic curves of ΔPVV, ΔSPVV, and ΔSPS for the diagnosis of TIPS dysfunction were 0.97, 0.96, and 0.87, respectively.

CONCLUSION

pSWE showed a diagnostic efficacy comparable to conventional ultrasound for diagnosing TIPS dysfunction and can be used routinely after TIPS procedures.

Identification of the Most Important Subset of Doppler, Laboratory, and Clinical Parameters for Serial TIPS Evaluation

OBJECTIVE. The purpose of the present study was to identify the subset of a wide range of serial Doppler, laboratory, and clinical parameters most predictive (both individually and in combination) of TIPS dysfunction in a large patient sample. MATERIALS AND METHODS. The medical records of 189 patients who had undergone TIPS procedures were analyzed. The patients (mean age, 52 years; 62% of whom were men) had undergone 1139 Doppler studies and 323 portovenograms. Laboratory parameters included model for end-stage liver disease (MELD) scores, serum albumin levels, presence of ascites, and time since last intervention. Doppler parameters included intrashunt velocities, temporal change in intrashunt velocities, main portal vein velocity, direction of flow in the left portal hepatic vein, and venous pulsatility index. Statistical analysis used ROC, univariate, and multivariate regression models to assess the parameters both individually and in combination. Shunt dysfunction was defined by a portosystemic gradient of more than 12 mm Hg. RESULTS. The laboratory and clinical parameters of greatest predictive value included the MELD score and the time since the last intervention. The Doppler parameters that were of greatest predictive value included the change in velocity at the hepatic venous end and the left portal vein flow direction. Multivariate models produced an AUC of 0.74. Differences between functional and dysfunctional shunts were also statistically significant for absolute velocity at the hepatic venous end, the change in velocity within the stent, and the temporal change in the mid shunt velocity. CONCLUSION. The subset of serial parameters most predictive of TIPS dysfunction are the temporal change in the velocity at the hepatic venous end, the absolute velocity at the hepatic venous end, the direction of flow in the left portal venous branch, and changes in the MELD score.

Noninvasive Detection of Clinically Significant Portal Hypertension in Compensated Advanced Chronic Liver Disease

Patients with compensated advanced chronic liver disease have different prognoses depending on the presence of portal hypertension. Current non-invasive diagnostic methods allow identification of clinically significant portal hypertension. Portosystemic collaterals on imaging or liver stiffness of more than 20 to 25 kPa by using transient elastography identifies patients with clinically significant portal hypertension. Patients with liver stiffness of less than 20 kPa and platelet count of greater than 150 g/L can avoid endoscopy. This rule could be expanded using spleen stiffness. Methods to risk stratify for portal hypertension in compensated advanced chronic liver disease and successfully treated chronic hepatitis C and B are subject of research.

Spleen Stiffness Performance in the Noninvasive Assessment of Gastroesophageal Varices after Transjugular Intrahepatic Portosystemic Shunts

Objectives

To investigate the performance of spleen stiffness (SS) by using two-dimensional shear-wave elastography (2D-SWE) for assessing the severity of gastroesophageal varices (GEVs) after transjugular intrahepatic portosystemic shunt (TIPS).

Methods

102 eligible patients were categorized as in the post-TIPS short-term (n = 69) and long-term (n = 38) follow-up groups. The performance of SS by using 2D-SWE for evaluating the severity of GEVs was compared with liver stiffness (LS), spleen stiffness-to-liver stiffness ratio (SS/LS), liver stiffness spleen-diameter-to-platelet-ratio score (LSPS), portal hypertension (PH) risk score, platelet count-to-spleen diameter ratio (PSR), and varices risk score by using receiver operating characteristic (ROC) curve and DeLong test.

Results

In the post-TIPS short-term follow-up group, area under the receiver operating characteristic curves (AUCs) of SS were 0.585 for mild (cutoff value = 30.3 kPa), 0.655 for moderate (cutoff value = 30.6 kPa), and 0.739 for severe (cutoff value = 31.9 kPa) GEVs, which were higher than other parameters for severe GEVs. AUCs of SS were lower than other parameters for mild and moderate GEVs, but no difference was found (p > 0.05). In the post-TIPS long-term follow-up group, AUCs of SS were 0.778 for mild (cutoff value = 28.9 kPa), 0.82 for moderate (cutoff value = 29.9 kPa), and 0.824 for severe (cutoff value = 37.7 kPa) GEVs, which were higher than other parameters except for severe GEVs. AUC of SS was lower than other parameters for severe GEVs, but no significant difference was found (p > 0.05).

Conclusion

SS is an effective noninvasive tool to predict GEV severity during the post-TIPS follow-up.

Approaches to the Diagnosis of Portal Hypertension: Non-Invasive or Invasive Tests?

Portal hypertension is the main driver of complications in patients with advanced chronic liver disease (ACLD) and is defined by values of hepatic venous pressure gradient measurement (HVPG) >5 mmHg. Values of HVPG ≥10 mmHg determine the presence of clinically significant portal hypertension (CSPH), the main predictor of the risk of variceal bleeding, hepatic decompensation, and mortality. However, its measurement is invasive and requires high expertise, so its routine use outside third level centers or clinical trials is limited. In the last decades, several non-invasive tests (NITs) have been developed and validated for the diagnosis of portal hypertension. Among these, liver (LSM) and spleen stiffness measurement (SSM) are the most promising tools available, as they have been proven accurate to predict CSPH, high-risk esophageal varices, decompensation, and mortality in patients with ACLD. In the last Baveno VI Consensus proceedings, LSM evaluation was recommended for the first time for diagnosis of CSPH (LSM >20-25 kPa) and the screening of patients with a low probability of having high-risk varices (LSM <20 kPa and platelet count >150.000/mm³). In this review, we aimed to summarize the growing evidence supporting the use of non-invasive tests for the evaluation of portal hypertension in patients with chronic liver disease.

Evaluation of spleen stiffness in healthy volunteers using point shear wave elastography

INTRODUCTION AND OBJECTIVES

This study aims to measure the values of spleen stiffness (SS) in healthy subjects, the inter-operator agreement in SS measurement, and to detect statistically significant correlations between SS and age, sex, weight, BMI, portal vein dynamics and splenic dimensions.

MATERIALS AND METHODS

The study included 100 healthy volunteers who had no substantial alcohol intake (<30g/daily for man, <20g/daily women), were negative on hepatitis B, hepatitis C, HIV blood serology, and had any history of lymphoproliferative disorders. Abdominal ultrasound, liver and spleen elastography were performed on each patient to search for focal splenic lesions, bile tract or portal vein dilatation, moderate/severe liver steatosis, and to measure liver and spleen stiffness.

RESULTS

The mean value was 18.14 (±3.08) kPa. In the group of men (n=49), the mean was 17.73 (±2.91) kPa, whereas in the group of women (n=51) it was 16.72 (±3.32) kPa. Statistical analyses showed no correlation between spleen stiffness and sex, age, weight, and BMI. Regarding their splenoportal axis, statistically significant differences in SS were found in the means of the two subgroups of subjects stratified by their portal flow velocity (p=0.003) and spleen area (p<0.001). Spearman's rank showed a weak association between SS and portal flow velocty (r=0.271) and splenic area (r=-0.237). ICC showed excellent (0.96) inter-operator agreement and Bland-Altman plot demonstrated no systematic over/under-estimation of spleen stiffness values.

CONCLUSIONS

Our results may serve as a reference point in the evaluation of SS especially in patients affected by advanced liver disease.

The Role of Spleen and Liver Elastography and Color-Doppler Ultrasound in the Assessment of Transjugular Intrahepatic Portosystemic Shunt Function

The reference standard for assessing transjugular intrahepatic portosystemic shunt (TIPS) function is venography with portosystemic pressure gradient (PPG) measurement. This procedure is invasive and expensive; thus, we assessed the feasibility, reproducibility and diagnostic accuracy of color-Doppler ultrasound (CDUS) and spleen and liver stiffness (LS) measurements for identifying TIPS dysfunction. Twenty-four patients (15 undergoing TIPS placement and nine undergoing TIPS revision) consecutively underwent CDUS examination and LS and spleen stiffness (SS) determination by transient elastography (TE) and point shear-wave elastography (pSWE). All parameters were taken before TIPS placement/revision (1-15 d before) and 24 h after, just before revision by venography. pSWE inter-observer agreement was assessed by intra-class correlation coefficient (ICC). CDUS and elastographic data were correlated (Pearson coefficient) with pressure gradients (hepatic venous pressure gradient [HVPG], PPG). Main determinants of TIPS dysfunction were investigated by linear regression. Forty-nine paired examinations were performed in total: 49 (100%) SS reliable measurements by pSWE and 38 (88%) by TE. The ICC for pSWE values was 0.90 (95% confidence interval [CI] 0.81‒0.94). SS values significantly correlated with HVPG and PPG (R = 0.51, p = 0.01). The area under the Receiver-Operating Characteristic (AUROC) curve of SS for diagnosing TIPS dysfunction was 0.86 (95% CI 0.70‒0.96) using a 25 kPa cutoff. At multivariate analysis, the flow direction of the intrahepatic portal vein branches and SS values were independently associated to TIPS dysfunction. The intrahepatic portal vein branches flow direction and SS value are two simple, highly sensitive parameters accurately excluding TIPS dysfunction. SS measurement by pSWE is feasible, reproducible and both positively and significantly correlates with HVPG and PPG values.

Shear wave elastography prior to transjugular intrahepatic portosystemic shunt may predict the decrease in hepatic vein pressure gradient

BACKGROUND

Transjugular intrahepatic portosystemic shunt (TIPS) is a procedure used to treat portal hypertension complications. Our aim was to evaluate liver and spleen stiffness measurement (LSM and SSM, respectively) changes using acoustic radiation force impulse imaging (ARFI) in comparison to Child-Pugh scores for predicting hepatic venous pressure gradient (HVPG) decreases after TIPS implantation.

METHODS

This prospective study included 31 consecutive clinically significant portal hypertension patients with TIPS indication. All patients received LSM and SSM before TIPS, at baseline, 2 days (follow-up 1) and 6 weeks (follow-up 2) post-implantation. HVPG was performed during the TIPS procedure.

RESULTS

The mean decrease in HVPG after TIPS was 63%. LSM and SSM decreased significantly between baseline and follow-up 2 (p < 0.001 and p < 0.001, respectively). At baseline, follow-up 1 and follow-up 2, significant correlations were detected between mean SSM and mean HVPG (p = 0.026; p = 0.018; p = 0.002, respectively). HVPG decreased to ≤ 10 mmHg in 61% of patients for which LSM, SSM, and Child-Pugh score were predictors (p = 0.033, p = 0.002 and p = 0.030, respectively). The area under the curve (AUC) for LSM, SSM, and Child-Pugh was 0.88, 0.90, and 0.84, respectively, with close sensitivity and specificity. SSM had the highest diagnostic accuracy for predicting an HVPG decrease to ≤ 10 mmHg in comparison to LSM and Child-Pugh score.

CONCLUSION

Spleen stiffness is superior to liver stiffness and Child-Pugh score as a non-invasive surveillance tool for evaluating patients with clinically significant portal hypertension (HVPG ≥ 10 mmHg) prior to TIPS.

Increase in liver stiffness after transjugular intrahepatic portosystemic shunt is associated with inflammation and predicts mortality

Transjugular intrahepatic portosystemic shunt (TIPS) efficiently treats complications of portal hypertension. Liver and spleen stiffness might predict clinically significant portal hypertension. This prospective study investigated liver stiffness in patients receiving TIPS regardless of indication. Of 83 included patients, 16 underwent transient elastography immediately before and 30 minutes after TIPS (acute group), while 67 received shear wave elastography of liver and spleen 1 day before and 7 days after TIPS (chronic group) and were followed further. In blood samples obtained before TIPS from cubital, portal, and hepatic veins, levels of several interleukins (IL1b, IL6, IL8, IL10, IL18) and interferon-gamma were analyzed. In 27 patients (5 acute, 22 chronic), it resulted in an increase in liver stiffness of >10%. In 56 patients, liver stiffness decreased or remained unchanged (<10%). Importantly, spleen stiffness measured by shear wave elastography decreased in all patients (chronic group). None of the clinical or laboratory parameters differed between patients with increase in liver stiffness and those without. Of note, patients with increased liver stiffness showed higher overall and/or hepatic venous levels of proinflammatory cytokines at TIPS and higher incidence of organ failure and worse survival after TIPS. C-reactive protein values and increase of >10% in liver stiffness after TIPS were the only independent predictors of mortality in these patients.

CONCLUSION

This study demonstrates that the presence of systemic inflammation predisposes patients to develop increased liver stiffness after TIPS, a predictor of organ failure and death. (NCT03072615) (Hepatology 2018;67:1472-1484).

Clinical applications of spleen ultrasound elastography - a review

In the last few years, notable technical progress has taken place in ultrasound elastography. Qualitative methods have been replaced by quantitative ones, such as: transient elastography, acoustic radiation force impulse and shear wave elastography. Owing to the fact that the spleen is superficially located, it is possible to obtain reliable measuring accuracy of its hardness using sonoelastography. Lately, many researchers have been investigating how spleen elasticity changes in patients infected with hepatitis B virus or hepatitis C virus and in patients suffering from liver fibrosis, portal hypertension, esophageal varices or myelofibrosis. In this article, we review the role and current status of accessible qualitative ultrasound elastography methods, including recent advances in the evaluation of spleen stiffness and its clinical utility. As study results demonstrate, spleen stiffness correlates with liver fibrosis and is helpful in determining the level of fibrosis in the METAVIR scoring system. In patients infected with hepatitis B virus or hepatitis C virus, spleen stiffness increases even when liver elasticity remains unaltered. Furthermore, it is useful in diagnosing portal hypertension or predicting existence of esophageal varices. Moreover, in patients suffering from biliary atresia after Kasai portoenterostomy, spleen sonoelastography may be helpful in selecting patients for liver transplantation as well as for choosing the best strategy for portal vein reconstruction before liver transplantation. In myelofibrosis, spleen stiffness correlates with bone marrow fibrosis and may be used to assess the response to treatment. Spleen sonoelastography is also useful in the monitoring of transjugular intrahepatic portosystemic shunt function.

Modification of splenic stiffness on acoustic radiation force impulse parallels the variation of portal pressure induced by transjugular intrahepatic portosystemic shunt

BACKGROUND AND AIM

Spleen and liver stiffness (LS) measured by acoustic radiation force impulse (ARFI) imaging has been shown to be useful in identifying patients with portal hypertension. The study aims to establish if the modification of portal pressure induced by a transjugular intrahepatic portosystemic shunt (TIPS) parallels the modification of spleen or LS measured by ARFI in order to understand if ARFI may be used to monitor the modification of portal pressure in patients with cirrhosis.

METHODS

Thirty-eight patients with severe portal hypertension underwent LS and spleen stiffness (SS) before TIPS and 1 week after TIPS. Portal atrial gradient (PAG) was measured before and after the shunt opening.

RESULTS

Portal atrial gradient decreased significantly from 19.5 to 6 mmHg (P < 0.001). SS decreased significantly after TIPS (pre-TIPS 3.7 m/s vs post-TIPS 3. 1 m/s; P < 0.001), and LS was also significantly modified by TIPS (pre-TIPS 2.8 m/s vs post-TIPS 2.4 m/s; P = 0.003). PAG and SS values measured before and after TIPS were significantly correlated (r = 0.56; P < 0.001); on the other hand, PAG and LS were not (r = 0.19; P = 0.27). Two patients developed a persistent hepatic encephalopathy refractory to medical treatment and were submitted to the reduction of the stent diameter. The modification of SS was parallel to the modification of PAG.

CONCLUSION

Spleen stiffness is superior to LS in detecting the modification of portal pressure induced by TIPS. This makes SS a potential non-invasive method to monitor the modification of portal hypertension. Further investigations are needed to establish applicability and clinical utility of this promising tool in the treatment of portal hypertension.

Point Shear Wave Elastography to Evaluate and Monitor Changing Portal Venous Pressure in Patients with Decompensated Cirrhosis

This study evaluated whether the stiffness of the liver and spleen, measured using the point shear wave elastography (pSWE) technique, correlates with portal venous pressure (PVP) and whether the result extends to estimate the diminishing change in PVP (ΔPVP) in patients with decompensated cirrhosis. We evaluated the data of 67 prospectively enrolled patients who underwent both transjugular intrahepatic portosystemic shunt (TIPS) and pSWE. The stiffness of liver and spleen were evaluated by measuring shear wave velocity (SWV) to determine the statistical correlation with PVP. We also analyzed whether change in SWV (ΔSWV) correlates with ΔPVP. The correlations were assessed with Spearman's rank correlation coefficients. Furthermore, receiver operating characteristic (ROC) curves were constructed to evaluate diagnostic capacity of ΔSWV. Spleen stiffness (SS) was positively correlated with PVP before and after TIPS (p < 0.002), although no correlation between liver stiffness and PVP was detected. A strong relationship between ΔSWV in SS and ΔPVP change in portal hypertension (r = 0.871) was also found in the overall population. The area under the ROC curve for the diagnosis of TIPS technical success was 0.869 and at a ΔSWV cut-off value of 0.36 m/s sensitivity was 77%. Measurement of SS can be used for non-invasive assessment and monitoring of PVP in patients with decompensated cirrhosis.