Non-invasive assessment of portal hypertension by multi-parametric magnetic resonance imaging of the spleen: A proof of concept study

Abstract

Background and aims: Non-invasive assessment of portal hypertension is an area of unmet need. This proof of concept study aimed to evaluate the diagnostic accuracy of a multi-parametric magnetic resonance technique in the assessment of portal hypertension. Comparison to other non-invasive technologies was a secondary aim.

Methods: T1 and T2* maps through the liver and spleen were acquired prior to trans-jugular liver biopsy and hepatic vein pressure gradient (HVPG) measurement. T1 measurements reflect changes in tissue water content, but this relationship is confounded by the presence of iron, which in turn can be quantified accurately from T2* maps. Data were analysed using LiverMultiScan (Perspectum Diagnostics, Oxford, UK) which applies an algorithm to remove the confounding effect of iron, yielding the "iron corrected T1" (cT1). Sensitivity, specificity, diagnostic values and area under the curve were derived for spleen cT1, liver cT1, transient elastography, and serum fibrosis scores. HVPG was the reference standard.

Results: Nineteen patients (15 men) with median age 57 years were included. Liver disease aetiologies included non-alcoholic fatty liver disease (n = 9; 47%) and viral hepatitis (n = 4; 21%). There was strong correlation between spleen cT1 and HVPG (r = 0.69; p = 0.001). Other non-invasive biomarkers did not correlate with HVPG. Spleen cT1 had excellent diagnostic accuracy for portal hypertension (HVPG >5 mmHg) and clinically significant portal hypertension (HVPG ≥10 mmHg) with an area under the receiver operating characteristic curve of 0.92 for both.

Conclusion: Spleen cT1 is a promising biomarker of portal pressure that outperforms other non-invasive scores and should be explored further.

Fig 1. Measurement of spleen cT₁ using LiverMultiScan.

Representative images from a patient with (top panel) and without (bottom panel) portal hypertension. Red circles on the T₁ and T₂* maps represent the region of interest where the measurements were taken. Abbreviations: HVPG: Hepatic vein pressure gradient, cT₁, iron corrected T₁.

Fig 2. Study flow diagram.

Abbreviations: MR: magnetic resonance, HVPG: hepatic vein pressure gradient, CSPH: clinically significant portal hypertension.

Fig 3. Spleen iron corrected T₁ (cT₁) correlation with the hepatic vein pressure gradient.

There was a strong association between spleen cT₁ and portal pressure as measured by the hepatic vein pressure gradient (HVPG, r = 0.69; p = 0.001). *Data from an outlying patient whose HVPG measurement was out of keeping with the rest of the clinical data raising the possibility of an inaccurate HVPG measurement.

Fig 4. Diagnostic accuracy of spleen and liver iron corrected T₁ (cT₁) for portal hypertension severity assessment.

(A) Receiver operating curves (ROC) of spleen and liver cT₁ for the diagnosis of any degree of portal hypertension. There was a significant diagnostic accuracy for spleen cT₁ with an area under the ROC (AUROC) of 0.92 (p = 0.002). Liver cT₁ had an AUROC of 0.73 with a trend towards significance (p = 0.110).(B) ROC curves of spleen and liver cT1 for the diagnosis of clinically significant portal hypertension. Both variables had significant diagnostic accuracy with AUROC of 0.92 (p = 0.002) for spleen cT1 and 0.81 (p = 0.026) for liver cT1.