METHODS AND APPARATUSES FOR MEDICAL IMAGING
First Claim
1. A catheter apparatus comprising:
- a nozzle system having exit holes around its periphery adapted to direct jets of an agent through the holes near, immediately proximate or immediately adjacent a portion of a vessel wall of a vessel to be imaged, a conduit connecting the nozzle system to an external or internal agent reservoir, at least one electronic flow controller and/or injector adapted to control a flow of the agent from the reservoir through the conduit to the nozzle system out of the holes, and a digital or analog processing unit adapted to control the controllers.
1 Assignment
0 Petitions
Accused Products
Abstract
A set of intravascular ultrasound (IVUS) related systems, apparatuses and methods are disclosed. New catheter designs including contrast agent introduction subsystems and/or Doppler subsystems are disclosed. Methods for acquiring and analyzing Doppler data from intravascular ultrasound (IVUS) catheters are disclosed. RF-based detection of blood and/or contrast agents such as micro-bubbles are disclosed. Methods for frame-grating image data analysis permitting frame registration before, during and after a contrasting effect is imposed on a system being imaged are disclosed. Methods for difference imaging for contrast detection are disclosed. Methods for quantification and visualization of IVUS data are disclosed. And methods for IVUS imaging are disclosed.
-
Citations
16 Claims
-
1. A catheter apparatus comprising:
-
a nozzle system having exit holes around its periphery adapted to direct jets of an agent through the holes near, immediately proximate or immediately adjacent a portion of a vessel wall of a vessel to be imaged, a conduit connecting the nozzle system to an external or internal agent reservoir, at least one electronic flow controller and/or injector adapted to control a flow of the agent from the reservoir through the conduit to the nozzle system out of the holes, and a digital or analog processing unit adapted to control the controllers. - View Dependent Claims (2, 3)
-
-
4. A method comprising the steps of:
-
positioning a probe adjacent a portion of a vessel, where the probe includes an intravascular ultrasound (IVUS) component and a Doppler component, transmitting a plurality of imaging pulses from the IVUS component into an region-of-interest (ROI), receiving echoes from the ROI by the IVUS component, matching or correlating the echoes to the image pulses to estimate a radial position of the stationary probe in the image, while maintaining the probe in a stationary orientation, switching to pulsed Doppler component;
detecting Doppler signals evidencing flow within the ROI where a suspected plaque, microvascularization or vasa vasorum site is located.
-
-
5. A radio-frequency (RF) detection, analysis and quantification method for IVUS comprising the steps of
obtaining RF-based IVUS data with or without an external contrast agent, and analyzing the RF-based IVUS data to determine features of the vessel.
-
11. A method implemented on a computer for detecting and analysis RF IVUS blood/saline/contrast agent data comprising the steps of:
-
training an algorithm to produce a optimal feature classifier including the steps of;
obtaining RF IVUS data including a plurality of frames from an appropriate region of interest (ROI) of a vessel, where the ROI evidences the presence of blood, saline and/or contrast agent, computing a number of features of the ROI, computing which features result in a best classification for a given classifier, selecting the given classifier, and optimizing parameters of the given classifier to produce the optimal feature classifier, and deploying the algorithm including the steps of;
using the optimal feature classifier to classify the RF IVUS data.
-
-
12. A method for frame gating comprising the steps of:
-
obtaining a sequence of frames representing a time period from a first time t1 to a second time t2;
selecting a frame similarity or dissimilarity metric, generating a frame dissimilarity matrix, generating a frame-similarity space by applying the metric to the dissimilarity matrix, generating clusters in the space using a clustering function, and selecting a particular frame ensemble from the resulting clusters.
-
-
13. A method for pullback frame gating comprising the steps of:
-
obtaining a pullback sequence of frames representing a time period from a first time t1 to a second time t2;
selecting a frame similarity or dissimilarity metric, generating a dissimilarity matrix, obtaining an initial estimate of a heartrate over the entire recording, tracing a path along an off-diagonal valley which represents a cardiac cycle length locally at each frame, applying zn x-shaped filter to find frame pairs associated with both high similarity and low motion, finding a single-phase associated pair that is at a maximally-stable point in the cardiac cycle, and using this point for tracing the filtered dissimilarity matrix upward and downward to collect the frames for the gated sequence.
-
-
14. A difference imaging-based detection method comprising the steps of:
-
positioning a catheter at a maximally-stenotic point of a suspect plaque or a region of interest (ROI);
imaging the ROI for a first period of time, generally on the order of 30 seconds, while holding the catheter steadily in place;
injecting a bolus dose of a contrast agent or contrast effect intra-coronarily, proximate the imaging catheter;
imaging the ROI for a second period of time, generally on the order of 30 seconds, again while holding the catheter steadily in place;
image-based frame gating the data to decimate a number of frames in the sequence of image frame collected in steps 2 and 4, providing a stabilized gated sequence with fewer frames than the original;
outlining an inner and outer contours of the ROI in the first frame of the gated sequence, performed either by an operator or an outlining routine;
propagating these contours to the remaining frames in the sequence, in order to provide a segmentation of each frame;
extracting a region between the contours into a rectangular raster in each frame, providing a stabilized space in which inter-frame comparisons of the ROI are to be performed;
averaging a pre-injection ROI images to obtain a pre-injection baseline of the non-contrast ROI;
subtracting the averaged baseline ROI pixel-wise from the pre- and post-injection ROI images to detect differences between the baseline appearance and the pre- and post-contrast appearance, where the pre-injection frames will rarely exhibit any changes as the pre-injection baseline is derived from them; and
mapping the difference-imaged ROIs back into the original IVUS space for visualization and quantification of the changes which occurred due to contrast perfusion.
-
-
15. A method comprising the steps of:
-
performing an intravascular ultrasound (IVUS) pullback analysis of a vessel, performing optionally pullback frame gating, analyzing each frame in the original or gated sequence for detection and qualification of VV dividing each image into four (4) quadrants constructing a map of the VV densities in each quadrant, and visualizing the VV densities associated with the pullback sequence of IVUS images.
-
-
16. A clinical method comprising the steps of:
-
positioning an IVUS imaging catheter in a vessel, after positioning, pulling back the catheter until a region-of-interest (ROI) segment of the vessel and a reference segment of the vessel are identified. after identifying the ROI segment and reference segment, re-positioning the catheter adjacent the ROI segment, collecting ROI images at a first frame collection rate for a first period of time, repositioning the catheter adjacent the reference segment, collecting reference images at a second frame collection rate for a second period of time, introducing a contrast agent, a collecting contrast reference images at a third frame collection rate for a third period of time, re-positioning the catheter adjacent the ROI segment, collecting contrast ROI images at a fourth frame collection rate for a fourth period of time, optionally while collecting images, exciting the contrast agent transthoracically during all or some of the third and/or fourth image collection period, administering adenosine, collecting adenosine ROI images at a fifth frame collection rate for a fifth period of time, removing the catheter is then removed, and analyzing the images to assess the presence of plaques and/or vasa vasorum (VV) within the ROI segment.
-
Specification