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Quantification of Portal Vein Vascularization Using an Automated Post-Processing Video Analysis Tool

Blood flow dynamics represent a diagnostic criterion for many diseases. However, no established reference standard is available. In clinical practice, ultrasound pulsed-wave Doppler (PW-Doppler) is frequently used to assess visceral blood flow, despite its well-known limitations. A quantitative analysis of conventional color Doppler patterns can be performed using an innovative ultrasound-based algorithm (pixel flow analysis, PFA). This tool already shows promising results in obstetrics, but the technique has not yet been evaluated for portal venous blood flow assessment.
Blank V, Heni M, Karlas T.
Ultrasound Int Open. 2023 Mar 20;9(1):E2-E10.
PMID: 36950090; PMCID: PMC10027440.
Methods This prospective exploratory research study evaluated the applicability of PFA in the portal venous system. Measurements of portal venous flow using PFA and PW-Doppler were compared in healthy volunteers (n=20) and in patients with hepatic steatosis (n=10) and liver cirrhosis (n=10).
Results In healthy volunteers (60% female, mean age 23 years, BMI 21.5 kg/m 2 [20.4-23.8]), PFA and PW-Doppler showed a strong positive correlation in fasting conditions (r=0.69; 95% CI 0.36-0.87), recording a median blood flow of 834 ml/min (624-1066) and 718 ml/min (620-811), respectively. PFA was also applicable in patients with chronic liver diseases (55% female, age 65 years (55-72); BMI 27.8 kg/m 2 (25.4-30.8)), but the correlation between PFA and PW-Doppler was poor (r=- 0.09) in the subgroup with steatosis. A better correlation (r=0.61) was observed in patients with liver cirrhosis.
Conclusion PFA and PW-Doppler assessment of portal venous vascularization showed high agreement in healthy volunteers and patients with liver cirrhosis. Therefore, PFA represents a possible alternative to conventional PW-Doppler sonography for visceral blood flow diagnostics and merits further evaluation.
Link (DOI)
Ultrasound speciality Portal Vein Vascularization


Short-Review by Prof. A. Saftoiu

This study evaluates the efficacy of Pixel Flow Analysis (PFA) in assessing portal venous blood flow, comparing it with the traditional Pulsed-Wave Doppler (PW-Doppler). Intravascular blood flow quantification, particularly in portal veins, is crucial for managing chronic liver diseases and post-liver transplantation care. However, existing noninvasive methods are limited, necessitating new techniques like PFA for comprehensive evaluation.

The study included healthy volunteers and patients with liver conditions like steatosis and cirrhosis. PFA, a noninvasive ultrasound-based method, analyzes color Doppler signals to assess blood flow across a vessel’s cross-sectional area. The method showed strong applicability and correlated well with PW-Doppler in healthy individuals and cirrhosis patients but less so in steatosis cases due to ultrasound signal attenuation.

PFA demonstrated potential in detecting flow changes, especially post-meal in healthy subjects, suggesting its usefulness in various clinical scenarios. The study, however, acknowledges limitations such as a small sample size and the absence of a noninvasive ‘gold standard’ for comparison. Despite these, PFA appears promising for noninvasive portal venous blood flow assessment and could complement existing methods like PW-Doppler. Further research is needed to establish its role in diagnosing and managing liver diseases.