Feasibility Exploration of Blood Flow Estimation by Contrast-Assisted Nakagami Imaging
Resource
Ultrasonic Imaging,30,133-150.
Journal
Ultrasonic Imaging
Pages
133-150
Date Issued
2008-07
Date
2008-07
Author(s)
Abstract
The microbubble contrast agent destruction/replenishment technique has been widely applied to ultrasound-based blood flow estimation. The rate of increase of the time-intensity curve (TIC) due to microbubbles flowing into the region of interest as measured from B-mode images closely reflects the flow velocity. In this study, we monitored microbubble replenishment by a proposed new approach called the time-Nakagami-parameter curve (TNC) obtained from Nakagami-parameter images for quantifying the flow velocity. The feasibility of using the TNC to estimate the flow was evaluated in computer simulations of the TIC and TNC for flow velocities from 10 to 30 cm/s under an ultrasound frequency of 5 MHz. The clutter effects on the TIC and TNC were explored in a more realistic situation by carrying out phantom measurements of 25 MHz. The rates of increase of the TIC and TNC were expressed by the rate constants β1 and βN of a monoexponential model, respectively. The average β1 increased from 38 to 110 s-1 as the flow velocity increased from 10 to 30 cm/s (r = 0.98), and the average βN increased from approximately 40 to 120 s-1 for the same increase in flow velocity (r = 0.98). The p-value between the results of β1 and βN as a function of flow velocity was 0.77. These results represent that βN quantifies the flow velocity similarly to the conventional β1. In particular, both the simulation and experimental results revealed that the TNC method conditionally tolerates the presence of nonperfused areas (e.g., surrounding tissues or vessel walls) in the region of interest without requiring application of an additional wall filter to cancel the influences of clutter echoes on the flow estimation. These findings suggest that the TNC-based technique may be a potential method as a complementary tool for the conventional TIC technique to improve the estimation of blood flow. Copyright 2008 by Dynamedia, Inc. All rights of reproduction in any form reserved.
Subjects
Blood flow; Contrast agent; Microbubble; Nakagami parameter
Other Subjects
Blood; Clutter (information theory); Hemodynamics; Image segmentation; Rate constants; Ultrasonic applications; Velocity; Blood flow; Blood flow estimation; Contrast agent; Micro-bubble; Microbubble contrast agents; Monoexponential models; Nakagami parameter; Time-intensity curves; Flow velocity
Type
journal article