Effect of Signal Intensity from the Accumulated Microbubbles in the Liver for Differentiation of Idiopathic Portal Hypertension from Liver Cirrhosis

Abstract

To examine the possibility of using contrast material-enhanced ultrasonography (US) to differentiate idiopathic portal hypertension (IPH) from cirrhosis. This was an institutional review board-approved prospective study with written informed consent. The study consisted of 23 patients (mean age, 60 years +/- 11; range, 37-85 years) with biopsy-proved cirrhosis, 10 patients (mean age, 65 years +/- 8; range, 51-78 years) with IPH, and 27 control subjects (mean age, 46 years +/- 17; range, 26-82 years) without any focal hepatic lesions or portal vein thrombosis. The patients underwent contrast-enhanced US for the observation of the right liver lobe. The time of the onset of contrast enhancement in the right hepatic artery and right portal vein was examined at vascular phase under continuous low-power emission, and signal intensity differences (in decibels) by using instantaneous high-power emission in the liver parenchyma were analyzed at late phase (15 minutes). Interobserver variability was quantified as coefficients of variation. Onset time of contrast enhancement in the right portal vein was significantly longer for both IPH (22 sec +/- 3.9, P = .0035) and cirrhosis (19.3 sec +/- 4.7, P = .04) patients than for control subjects (17 sec +/- 3.3), with no significant difference in the onset time in the right hepatic artery. Images obtained in both IPH patients (21.2 dB +/- 1.4) and control subjects (22.1 dB +/- 2.2) had significantly higher signal intensity differences than those obtained in cirrhosis patients (13.8 dB +/- 2.8, P < .0001), with no significant difference between images of IPH patients and control subjects. Signal intensity differences of more than 18 dB had 100% sensitivity and specificity for the diagnosis in IPH patients and control subjects. Interobserver variability for signal intensity differences was 8.7%. Contrast-enhanced US may offer the possibility for a simple, easy, and noninvasive diagnosis of IPH.