Contrast-Enhanced Subharmonic Hepatic Vein Signal As an Imaging Screening Test for Portal Hypertension
Abstract
Purpose
Portal hypertension (PH) is currently diagnosed by the hepatic venous pressure gradient (HVPG). Subharmonic imaging (SHI) is a contrast-enhanced ultrasound (CEUS) imaging technique receiving at half the transmit frequency resulting in better tissue suppression. The aim of the study was to determine if the presence of SHI signals inside the hepatic vein (HV) can be used as a qualitative screening sign of PH.
Methods
Patients undergoing HV catheterization to acquire HVPG measurements also underwent a SHI CEUS examination of portal vein (PV) and HV using a modified LOGIQ 9 or E10 scanner (GE HealthCare) with 4C or C1-6 probe. SHI in this implementation had 1.25MHz (received) and 2.5MHz (transmitted) frequencies. The scanner was equipped with a calibration algorithm to allow for SHI optimization of acoustic pressures on an individual subject basis. Images were acquired during the infusion of the ultrasound contrast agent Sonazoid (GE HealthCare) and analyzed for the presence or absence of SHI signals in HV. SHI findings were compared to findings on HVPG measurement.
Results
Currently, 167 patients had their data analyzed, 87 had increased HVPG values corresponding to subclinical and clinical PH, while 80 patients had normal HVPG values. Qualitative assessments showed all cases with increased HVPG values SHI signal seen in HV. Among the 80 cases with normal HVPG values, 68 cases had no SHI signal in HV. Overall accuracy of presence of SHI signals in HV for diagnosis of PH was 93% (155/167), sensitivity of 100% (87/87) and specificity of 85% (68/80).
Conclusion
The presence of optimized SHI signals inside HV can be used as a qualitative screening test for PH. This is a noninvasive and safe method that could be used as a new initial, qualitative sign of PH minimizing the need for invasive procedures.