Noninvasive Subharmonic Aided Pressure Estimation of Portal Hypertension; Renewal

For each SHAPE study (Cohorts 1, 2, 3 and 4), a dose of three vials with 60 μL of Sonazoid microbubbles (6 mL) will be prepared. An infusion of Sonazoid (1.44 μL microbubbles/kg/hour) and saline (120 mL/hour) through an IV line in the antecubital vein (or, if need be, in another suitable vein) will be started. The duration of contrast agent infusion will range from 6 to 10 minutes. For the direct contrast agent comparison in Cohort 1, two vials of Definity will be mixed and diluted in 50 mL of normal saline, yielding a concentration of 49.4 μL/mL, and infused over approximately 10-12 minutes. A waiting period of at least 30 minutes will be observed in Cohort 1 between infusing contrast agents and the order of the contrast agents will be randomized. Once the infusion of contrast has started, ultrasound imaging will be performed with the C1-6-D curvi-linear array (GE Healthcare) to guide SHAPE ROI placement into the portal vein (while also visualizing a hepatic vein). The SHAPE optimization algorithm will be activated and the acoustic power will be adjusted to produce the maximum change in subharmonic amplitudes (i.e., maximizing the sensitivity of SHAPE). Subharmonic raw DICOM data from the microbubbles (i.e., SHAPE) will be acquired at the optimal acoustic power setting in 5 s segments during the infusion of the Sonazoid (or Definity) suspension. All measurements will be repeated three times to allow for averaging of the resulting SHAPE pressure estimates. The SHAPE pressure estimates will be calculated on the Logiq E10 and recorded. Finally, all digital clips will be transferred off-line for backup and to permit repeat calculations of the portal pressure estimates in case new processing parameters are developed as part of this study.