摘要:
A method of evaluating tissue stiffness of a target area includes positioning an ultrasound elasticity imaging apparatus adjacent a surface of an area of tissue where the target area is located and applying a dynamic range of force to the tissue. A plurality of ultrasound beams can be directed at the tissue and a plurality of ultrasound echoes can be acquired from the strained tissue in the target area to calculate an amount of developed strain within the target area.
摘要:
A method of evaluating tissue stiffness of a target area includes positioning an ultrasound elasticity imaging apparatus adjacent a surface of an area of tissue where the target area is located and applying a dynamic range of force to the tissue. A plurality of ultrasound beams can be directed at the tissue and a plurality of ultrasound echoes can be acquired from the strained tissue in the target area to calculate an amount of developed strain within the target area.
摘要:
Methods and systems for measuring mechanical property of a vascular wall and a method and system for determining health of a vascular structure are provided wherein local deformation of a vessel wall resulting from physiologic pressures with altered transmural forces is measured. A non-invasive free-hand ultrasound scanning-procedure was performed to apply external force, comparable to the force generated in measuring a subject's blood pressure, to achieve higher strains by equalizing the internal arterial baseline pressure. When the applied pressure matched the internal baseline diastolic pressure, strain and strain rate increased by a factor of 10 over a cardiac cycle. Radial arterial strain was assessed in the vessel wall over the entire deformation procedure using a phase-sensitive, two-dimensional speckle-tracking algorithm. An elastic modulus reconstruction procedure was developed to estimate the non-linear elastic properties of the vascular wall.
摘要:
An optimized elastic modulus reconstruction procedure can estimate the nonlinear elastic properties of vascular wall from intramural strain and pulse wave velocity (PWV) measurements. A noninvasive free-hand ultrasound scanning procedure is used to apply external force, comparable to the force in measuring a subject's blood pressure, to achieve higher strains by equalizing the internal arterial baseline pressure. PWV is estimated at the same location where intramural strain is measured. The reconstructed elastic modulus is optimized and the arterial elastic modulus can be determined and monitored using a simple dual elastic modulus reconstruction procedure.
摘要:
An ultrasonic imaging system acquires echo signals from an object being imaged such as a moving coronary artery and the cross-correlation between echo signals is employed as an objective measure of relative object location. The method is used in a prescan procedure to determine an optimal gating window to acquire image data during a cardiac gated scan, and it is used during the scan as a real time gating signal.
摘要:
A 3D image data set representing a volume of material such as human tissue is created using speckle decorrelation techniques to process successive 2D data slices from a moving, standard 1D or 1.5D ultrasound transducer. This permits the use of standard ultrasound machinery, without the use of additional slice-position hardware, to create 3D images without having to modify the machinery or its operation. Similar techniques can be used for special data processing within the imaging system as well to expedite the image acquisition process. Optionally, the image quality of 2D images can be enhanced through the use of multiple 3D data sets derived using the method.
摘要:
A system and method are provided for determining the performance of a vessel, such as a hemodialysis access, which communicates blood between two locations of a patient. A conduit, such as an external dialysis circuit or an intravascular catheter, is provided in fluid communication with the vessel, and has a diversion point for diverting blood from the vessel into the conduit. The system further includes means for determining a flow rate of the diverted blood through the conduit. A first sensor in communication with the vessel generates at least one signal that is a function of a blood flow rate in the vessel downstream from the diversion point, wherein the downstream flow rate depends on the determined conduit flow rate and the performance of the vessel can be determined based on the signal. In addition, a processor can be provided in communication with the first sensor for determining a flow rate in the vessel upstream from the diversion point from the signal and the conduit flow rate. In a preferred embodiment, the first sensor is an ultrasonic sensor, and the at least one signal represents a time-averaged mean Doppler velocity of blood flow. Still further, additional sensors may be employed to provide a measure of the upstream flow rate as well as the conduit flow rate.
摘要:
The volume of fluid flow within a vessel (VE) is measured by an ultrasound system. Ultrasound waves backscattered from the fluid within the vessel generate data from which velocity values representing components of velocity (Vx and Vy) of the fluid flow in the scan plane (IP) are calculated. Grayscale data is correlated and the rate of decorrelation (D) of the data is calculated. The volume flow of the fluid (F) is estimated in response to the velocity signals and the rate of decorrelation (D).
摘要:
A method for quantitatively estimating the amount of tissue that contains moving blood using power Doppler ultrasound. A region of interest is identified from a frozen image (i.e., a snapshot screen display created by displaying the last real-time image for a given scan). The region of interest is specified by using a pointing device (e.g., a mouse). An object that contains one hundred percent blood flow and is located at the same depth as the region of interest, but not necessarily inside the region of interest, is identified and the corresponding power noted and designated as the reference power level. The display is adjusted to show the one hundred percent blood flow vessel in a designated color (such as, for example, green) and all other power levels are normalized to the reference power level. The fractional blood volume is quantitatively estimated by summing the normalized Doppler power levels in a region of interest and dividing the sum by the number of pixels in region of interest. The numerical result for the specified region of interest may be shown on the display of the ultrasound scanner.
摘要:
An x-ray CT system performs a scan by acquiring projection views from which an image is reconstructed. In a prospective embodiment, the correlation of adjacent views is calculated as the scan is performed and is used to detect subject motion as the scan is being performed. In a retrospective embodiment, the correlation of adjacent views is calculated and is used to detect subject motion after the scan is completed. In the first embodiment substitute projection views are acquired by continuing the scan and in the second embodiment redundant projection views acquired during the scan are substituted until the best possible image is produced.