This study is a prospective, non-controlled, multicentre trial in patients with cirrhosis or portal hypertension. In this study, the investigators aim to establish the HVPG using biofluid mechanics (HVPGBFM) model using biofluid mechanics methods and validate the HVPGBFM model. A total of 200 patients will be recruited in this study and each patient will undergo computed tomography, blood tests, Doppler ultrasound and HVPG measurement. The study consists of two independent and consecutive cohorts: original cohort (100 patients) and validation cohort (100 patients). The researchers will establish and improve the HVPGBFM model in the original cohort and assess the model in the validation cohort.

Consecutive patients are randomly assigned 1:1 to either the original cohort or the validation cohort. Randomization is based on the computer-generated random digits table. This study consists of two independent and consecutive stages:

1. Establishment and improvement of the HVPGBFM model: For 100 patients in the original cohort, biofluid mechanics specialists will use each patient's computed tomography, blood tests, Doppler ultrasound and HVPG results to adjust the parameters of the HVPGBFM model in order to make each patient's HVPGBFM and HVPG values match well.
2. Assessment of the HVPGBFM model: For 100 patients in the validation cohort, biofluid mechanics specialists will use each patient's computed tomography, blood tests and Doppler ultrasound results to calculate each patient's HVPGBFM according to the HVPGBFM model established previously. Biofluid mechanics specialists will make no changes to the HVPGBFM model and will have no access to patients' HVPG results in this cohort. Finally, the researchers will compare each patient's HVPGBFM and HVPG value and make an assessment of the HVPGBFM model.

Each patient's HVPG measurement will be performed after finishing computed tomography, blood tests and Doppler ultrasound. These results and other clinical data will be inaccessible to professionals for HVPG measurements in order to prevent certain biases. Each patient's computed tomography, blood tests, Doppler ultrasound and HVPG measurement will be performed within 30 days and treatments that may affect HVPG value will be avoided during this period.

Inclusion Criteria:

• Be at least 18 years of age.
• Patients with cirrhosis or portal hypertension, scheduled for HVPG measurement.

Exclusion Criteria:

• Female patients who are pregnant or nursing.
• Patients who are medically unstable, terminally or seriously ill, or patients whose clinical course is unpredictable.
• Patients with clinically unstable cardiac disease, for example: congenital heart defect, arrhythmia, uncontrolled heart failure (NYHA Class IV).
• Patients with respiratory distress syndrome or clinically unstable pulmonary disease, for example: pulmonary hypertension, pulmonary emboli, pulmonary vasculitis, emphysema.
• Patients with severe coagulation disorders.
• Patients with unstable occlusive disease or thrombosis within the hepatic, portal, or mesenteric veins.
• Patients who are allergic to iodinated contrast.