Introduction to elastography

Elastography is an easy, non-invasive examination which allows the evaluation of tissue stiffness using an ultrasound probe that generates mechanical impulses. Liver elastography has already established itself as an important tool that helps determine the severity of liver disease without the need for invasive procedures such as liver biopsy. In recent years, new reports and studies have emerged describing spleen elastography as a novel and useful tool that may support diagnostic and therapeutic decision-making in patients with liver diseases. An increasing number of studies indicate potential groups of patients in whom spleen elastography may be of value.

Spleen elastography: overview

The development of portal hypertension in patients with chronic liver disease still poses a great clinical challenge. Disease progression may lead to serious complications such as ascites, hepatic encephalopathy, decompensation of liver cirrhosis and acute variceal hemorrhage. It is important to note that, based on the current evidence, liver biopsy remains the gold standard for assessment and staging of liver fibrosis. Hepatic venous pressure gradient (HVPG) is a key tool in measuring portal hypertension, and upper gastrointestinal endoscopy is the method of choice for evaluating the presence of esophageal varices. However, various non-invasive tests have emerged over the last years, including elastography-based imaging techniques such as liver stiffness measurement (LSM). A growing number of studies demonstrate the effectiveness of these methods in both staging the severity of liver disease and serving as valuable prognostic factors, which is reflected in current guidelines (including the Baveno VII consensus) [1]. With the spleen playing a key role in portal circulation, its elastographic features may provide valuable information and complete the already existing limitations of LSM. The recent Baveno VII renewed consensus in portal hypertension emphasizes the clinical usefulness of liver ultrasound elastography, which has been validated in long-term observational studies [2-4]. It also highlights spleen stiffness measurement (SSM) as an important and promising clinical tool.

Measurement of spleen stiffness using the standard 50 Hz liver module in vibration-controlled transient elastography (FibroScan; Echosens) was first proposed by Stefanescu et al. in 2011 [5] as a complementary tool for non-invasive identification of high-risk varices. Since this innovative publication, several authors have successfully demonstrated that spleen stiffness measurement correlates with clinically significant portal hypertension (CSPH) and is able to accurately predict the severity of esophageal varices or even liver-related adverse outcomes in patients with chronic liver diseases [6]. Moreover, spleen stiffness abnormalities, unlike those in the liver, show a correlation with portal pressure variations during non-selective β-blocker therapy [7], as well as with fluctuations in pressure gradients in patients undergoing transjugular intrahepatic portosystemic shunt (TIPS) placement [8]. These results suggest that spleen elastography may show a more precise reflection of dynamic changes and provide additional information, as compared to liver elastography.

Techniques of spleen elastography

Among several techniques of performing spleen elastography, transient elastography (TE) appears to be the most prominent due to its reliability and wide clinical application. TE, specifically vibration-controlled transient elastography (VCTE), is a non-invasive imaging technique that quantifies tissue stiffness by sending low-frequency mechanical vibrations and measuring shear-wave propagation via ultrasound. In a study by Rigamonti et al. [9], a spleen-dedicated 100 Hz VCTE module was used and demonstrated high reproducibility with low inter- and intra-operator variability even in patients with chronic liver disease. Another study by Zhang et al. [10] showed that 100 Hz VCTE has outstanding feasibility, with a high success rate in measuring spleen stiffness, and a correlation between spleen and liver stiffness – suggesting its potential utility in assessing portal hypertension. The main advantages of this technique include its safety, repeatability, and rapid execution, making it an attractive tool for non-invasive monitoring of liver and spleen pathology. TE remains the only spleen elastography technique referenced in the Baveno VII consensus recommendations up to the date of this publication [1].

Other techniques of spleen elastography include point shear-wave elastography (pSWE), which quantifies shear-wave velocity within a single focused region of interest, and two-dimensional shear-wave elastography (2D-SWE), which provides a real-time elastographic map across a wider tissue area. However, in healthy individuals, Nowotny et al. [11] demonstrated that absolute stiffness values obtained by these methods are not interchangeable across different manufacturers or anatomical regions of the spleen, underscoring substantial inter-device variability and limited cross-platform comparability. Conversely, the clinical study by Fofiu et al. [12], conducted in patients with compensated cirrhosis, showed that both pSWE and 2D-SWE offer high feasibility and comparable diagnostic performance for predicting the presence of varices requiring therapeutic intervention. Although these findings suggest that both techniques may serve as reliable non-invasive tools, further studies are required to clarify their optimal clinical integration.

Measurement conditions

As observed by Kjærgaard et al. [13], both the liver and spleen stiffness values rose significantly after consumption of moderate- and high-calorie meals, irrespective of fibrosis stage or elastography technique employed. Moreover, the authors suggested that this phenomenon may lead to clinically relevant misclassification, underscoring the need for an adequate fasting period of at least 3 hours prior to spleen elastography. Another study conducted by Armandi et al. [14] demonstrated that transient elastography of spleen stiffness at 100 Hz showed reduced intra-examination variability when more measurements were taken. The authors recommended acquiring at least 15 scans per examination, especially when stiffness values are high (> 75 kPa), to maintain absolute deviations within ±5 kPa at the 95% confidence interval.

Current recommendations – Baveno VII consensus

According to current recommendations – the Baveno VII consensus on the management of portal hypertension – spleen transient elastography has defined but very limited clinical applications. The consensus highlights its implementation in patients with viral hepatitis (untreated HCV infection and treated or untreated HBV infection). The exclusion and confirmation thresholds for CSPH are < 21 kPa and > 50 kPa, respectively, for spleen elastography performed with a probe generating 100 Hz shear waves, though the consensus notes that further validation is required to determine optimal cut-off values. Additional research is needed to define CSPH in other etiologies of chronic liver disease.

The second indication for spleen elastography, as stated in the consensus, concerns patients in whom non-selective beta-blockers are contraindicated and who are therefore recommended to undergo upper GI endoscopy, according to the Baveno VI criteria for liver elastography (LSM by TE ≥ 20 kPa or platelet count ≤ 150 × 10⁹/l). This group of patients may be further divided based on spleen stiffness on TE examination. In those with low probability of high-risk varices (SSM ≤ 40 kPa), endoscopy may safely be avoided.

The Baveno VII consensus outlines key directions for future research to improve the assessment and management of portal hypertension, emphasizing the need for introducing more robust, evidence-based and non-invasive strategies. Priorities in this field include validating the prognostic value and specific HVPG cut-offs in different liver diseases. Notably, the consensus also emphasizes the need for evaluation of non-invasive tests, indicating spleen elastography as a promising tool for improving risk stratification and prognosis assessment in portal hypertension.

Novel clinical applications

Recent publications suggest possible implementation of spleen elastography in supporting differential diagnosis of liver disease etiology. A study conducted by Elshaarawy et al. [15] found the SSM to LSM ratio to be significantly higher in patients with hepatitis C virus infection (HCV) compared to those with alcohol-related liver disease (ALD), regardless of fibrosis stage (3.8 vs. 1.72; p < 0.0001). Moreover, higher SS/LS and spleen length to LS ratios in HCV reflect a predominance of portal hypertension related complications (e.g., variceal hemorrhage) in HCV vs. liver-failure events in ALD. These findings suggest that combined measurement of LS and SS (or spleen length) provides additional information on disease etiology and may assist clinicians in predicting disease-specific complications. In another study, Sebesta et al. [16] found SSM/LSM ratio to vary significantly between liver disease etiologies: patients with MASH were observed to present a higher ratio compared to those with ALD, even after disease severity adjustments were made. According to the authors, the results of their study supports the hypothesis of a presinusoidal component of portal hypertension in MASH, not captured by conventional measures. However, the number of similar studies is very limited.

Research published by Meister et al. [17] evaluated a total of 159 valid liver and spleen stiffness measurements and further analyzed patients in a clinical follow-up. The results demonstrated that TE SSM could differentiate between acute and chronic liver disease. Patients with comparable LSM who suffered from acute liver disease had significantly lower SS as compared to patients with chronic liver failure (30.97 vs. 46.03 kPa; p = 0.04). Moreover, acute liver failure was associated with elevation in LS measurement (16.47 kPa) but not in SS (30.97 kPa). SSM may also serve as a prognostic factor for liver cirrhosis decompensation (12 patients developed liver cirrhosis decompensation; with a SS > 39 kPa (p = 0.0005). However, it is important to note that this study was limited by a heterogeneous sample and technical aspects of performing SSM. Clearly, this puts more emphasis on the need to validate threshold values and confirm the clinical relevance of these findings.

Jachs et al. [18] conducted a multicenter modelling study with external validation cohorts evaluating SSM using 100 Hz vibration-controlled transient elastography in 407 patients with compensated advanced chronic liver disease, with hepatic venous pressure gradient as the reference. SSM 100 Hz showed high diagnostic performance for CSPH (area under the curve [AUC] ~0.89-0.91), with optimal rule-in/rule-out performance around ~40-50 kPa. Compared with the ANTICIPATE model (LSM and platelet-based), the NICER model (integrating SSM, LSM, platelet count, body mass index [BMI]) demonstrated superior performance, with AUC ~0.92-0.93 vs. ~0.86-0.88, higher negative predictive value (NPV; ~97-99% vs. ~93-95%) and positive predictive value (PPV; ~90-93% vs. ~80-85%), as well as a reduction of the indeterminate “grey zone” by approximately 30-40%. The NICER model improved patient reclassification and overall diagnostic accuracy, particularly in intermediate-risk populations, compared with the ANTICIPATE model approach.

Xu et al. [19], presented a narrative review of SSM in portal hypertension, summarizing evidence from multiple prospective, retrospective, and cross-sectional studies across different etiologies of chronic liver disease. Diagnostic thresholds (e.g. Baveno VII criteria) were originally derived in viral etiologies, which is relevant when extrapolating cut-offs to non-viral populations. The review analyzed four main elastography techniques: TE (50 Hz and spleen-dedicated 100 Hz), point SWE (pSWE/ARFI), two-dimensional SWE (2D-SWE), and magnetic resonance elastography (MRE). Across studies using HVPG as the reference, SSM showed a strong correlation with portal pressure and higher diagnostic accuracy than LSM, with reported performance typically AUC ~0.80-0.92. Technique-specific SSM thresholds were summarized. For TE (aligned with Baveno VII, viral etiology), < 21 kPa ruled out CSPH and > 50 kPa ruled in CSPH. For 2D-SWE, optimal cut-offs for CSPH were ~26.6-27.9 kPa (sensitivity up to 98.6-100%, specificity ~60-70%). For variceal screening, SSM ≤ 46 kPa combined with Baveno VI criteria allowed avoidance of ~37-44% of endoscopies with < 5% missed high-risk varices, while spleen-dedicated 100 Hz TE improved rule-out thresholds (e.g. ≤ 41.3 kPa). Additional reported thresholds included ~13.2 kPa (2D-SWE) and 2.91 m/s (pSWE) for varices detection (AUC up to 0.84-0.90). The review also highlighted prognostic applications: SSM ≥ 74 kPa was associated with non-response to β-blockers (sensitivity and NPV 100%), and ≥ 10% decrease in SSM reliably reflected haemodynamic response (AUC up to 0.97). Importantly, the authors noted variability of cut-offs across techniques and the potential influence of etiology (viral vs. non-viral), emphasizing the need for etiology-specific validation despite broadly consistent performance across disease groups.

A high-quality individual patient data meta-analysis by Elton Dajti et al. [20] evaluated the diagnostic performance of SSM for detecting CSPH in compensated advanced chronic liver disease. The analysis included 17 studies (n = 1245) and assessed SSM obtained mainly by vibration-controlled transient elastography, with hepatic venous pressure gradient as the reference standard. Within Baveno VII criteria-based algorithms, CSPH could be ruled out using LSM ≤ 15 kPa and platelet count ≥ 150 × 10⁹/l, extended by SSM < 21 kPa (dual-cutoff) or SSM ≤ 40 kPa (single-cutoff). CSPH could be ruled in using SSM > 50 kPa in combination with LSM ≥ 25 kPa and/or platelet count ≤ 150 × 10⁹/l (dual-cutoff) or SSM > 40 kPa (single-cutoff). The dual-cutoff SSM model showed excellent performance, with sensitivity of 100% and NPV of 98% for ruling out CSPH, and specificity of 89% with PPV 93% for ruling in disease, while significantly reducing the indeterminate zone. These findings support the integration of spleen elastography with LSM and platelet count as a robust, non-invasive strategy for CSPH stratification.

Conclusions

Spleen elastography has emerged as a valuable non-invasive tool in the assessment of portal hypertension, offering clinically relevant insights into hemodynamic alterations associated with chronic liver disease. Current evidence indicates that SSM may facilitate the identification of patients at risk of liver cirrhosis decompensation and enable monitoring of disease progression. Moreover, when combined with liver elastography, SSM provides complementary information that can enhance diagnostic accuracy, refine risk stratification, and guide more targeted therapeutic interventions. Importantly, the cited studies demonstrate the development of increasingly accurate non-invasive models (e.g. incorporating SSM with liver stiffness measurement and platelet count), which allow reliable identification of CSPH, including effective rule-in and rule-out strategies. These findings support the integration of SSM into clinical algorithms and protocols. Nevertheless, current evidence remains limited by study heterogeneity and sample size, and further research is warranted – particularly to validate these models across different etiologies of liver disease and to establish standardized, widely applicable cut-off values for routine clinical practice.

Disclosures

This research received no external funding.

Institutional review board statement: Not applicable.

The authors declare no conflict of interest.

References