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EP-4551123-B1 - SYSTEM FOR REGISTERING IMAGES OBTAINED USING DIFFERENT IMAGING MODALITIES

EP4551123B1EP 4551123 B1EP4551123 B1EP 4551123B1EP-4551123-B1

Inventors

  • BROKMAN, Omer
  • LEVY, YOAV
  • NAFTALIS, Netanel

Dates

Publication Date
20260506
Application Date
20230707

Claims (15)

  1. A system for registering first and second devices affecting internal anatomic tissue, the system comprising one or more processors (116, 146, 156) configured to: operate the first device to: create a tissue disruption at a target region in the internal anatomic tissue; and detect a location of the tissue disruption in the target region; operate the second device to: obtain an image of the target region; and detect a location of the tissue disruption in the image; register a first coordinate reference frame of the first device and a second coordinate reference frame of the second device to a common coordinate reference frame based on (i) the location of the tissue disruption in the target region detected by the first device and (ii) the location of the tissue disruption in the image detected by the second device.
  2. The system of claim 1, wherein the first device is an ultrasound transducer system (150, 205) and the second device is a magnetic-resonance imaging, MRI, system (102, 210).
  3. The system of claim 1 or claim 2, wherein the one or more processors (116, 146, 156) are configured to register the first and second coordinate reference frames to the common coordinate reference frame by assigning the same location in each of the first and second coordinate reference frames to the tissue disruption in the target region.
  4. The system of claim 1 or claim 2, wherein the one or more processors (116, 146, 156) are configured to register the first and second coordinate reference frames to the common coordinate reference frame by establishing a coordinate transformation to relate one of the first and second coordinate reference frames to the other of the first and second coordinate reference frames.
  5. The system of claim 4, wherein the one or more processors (116, 146, 156) are configured to operate one of the first and second devices to communicate the coordinate transformation to the other of the first and second devices.
  6. The system of any of claims 2-5, wherein the tissue disruption is visualizable by MRI and/or computationally detectable in a T2 MR image or in a T2* MR image.
  7. The system of any of claims 2-6, wherein the tissue disruption is a transient disruption.
  8. The system of any of claims 2-7, wherein the one or more processors (116, 146, 156) are configured to operate the ultrasound transducer system (150, 205) to induce acoustic cavitation at the target region, and the tissue disruption is mechanically ruptured tissue caused by the acoustic cavitation.
  9. The system of any of claims 2-7, wherein the one or more processors (116, 146, 156) are configured to (i) operate a source of ultrasound contrast agent including a suspension of microbubbles and (ii) cause the ultrasound contrast agent to be administered such that the ultrasound contrast agent reaches the target region before the first device is operated to create the tissue disruption at the target region.
  10. The system of any of claims 2-7, wherein the one or more processors (116, 146, 156) are configured to operate the ultrasound transducer system (150) to increase permeability of tissue at the target region, and the tissue disruption is the increase in permeability.
  11. The system of claim 10, wherein the tissue is a blood-brain barrier.
  12. The system of claim 11, wherein the one or more processors (116, 146, 156) are configured to cause MRI contrast agent to be administered so it is present at the target region when the second device is operated to obtain the image.
  13. The system of any of claims 2-7, wherein the one or more processors (116, 146, 156) are configured to operate a source of ultrasound contrast agent including a suspension of microbubbles and a source of MRI contrast agent so that the ultrasound contrast agent and the MRI contrast agent are present at the target region when the second device is operated to obtain the image.
  14. The system of any of claims 1-13, wherein the one or more processors (116, 146, 156) are configured to operate the first device to record signals from tissue at the target region and to detect the location of the tissue disruption based at least in part on the signals recorded by the first device.
  15. The system of claim 14, wherein the one or more processors (116, 146, 156) are configured to operate the first device to generate a second image of the target region from the signals recorded by the first device, and detect the location of the tissue disruption in the second image.

Description

TECHNICAL FIELD The present disclosure relates to imaging, and, more specifically, to systems and methods for registering images and/or verifying image registrations obtained using various imaging modalities. BACKGROUND Medical imaging of internal organs provides important anatomic and diagnostic information, which medical personnel can employ to make therapeutic decisions. Medical images can be acquired using various non-invasive imaging procedures, such as computed topography (CT), magnetic resonance imaging (MRI), or ultrasound imaging. A CT system transmits x-rays through an anatomic site of interest, and based on the attenuation coefficients of the x-rays, cross-sectional images ("slices") of the object can be reconstructed. As a result, CT scans are well suited to viewing details of bony structures, diagnosing diseases of the lung and chest, and detecting cancers. Advantages of CT imaging include, for example, a short scan time for a complete scan (typically less than five minutes), low cost (about half the price of an MRI apparatus), the ability to accurately outline bony tissue inside the body, fewer motion artifacts due to fast imaging speeds (each scan time is less than 30 seconds), etc. CT systems, however, irradiate the patient and pose consequent risk; for this reason, CT scans are not recommended for pregnant women or children. Ultrasound imaging, which involves passing high-frequency acoustic waves through the body, is another widely used technique. Ultrasound waves penetrate well through soft tissues and, due to their short wavelengths, can be focused to spots with dimensions of a few millimeters. In a typical ultrasound examination, a transducer probe is placed directly on the skin or inside a body opening. A thin layer of gel may be applied to the skin to provide direct contact between the transducer probe and skin and thereby allow efficient transfer of ultrasound energy into the body. An ultrasound image of internal anatomic structures can be constructed from the waves reflected by those structures - in particular, for example, from the amplitudes and phases of the reflection signals and/or the time it takes for the ultrasound waves to travel through the body. Because ultrasound images are captured in real-time, they can also show movement of the body's internal organs as well as blood flowing through the blood vessels. In addition, ultrasound imaging offers high temporal resolution, high sensitivity to acoustic scatterers (such as calcifications and gas bubbles), excellent visualization, low cost, portability, and no ionizing radiation exposure, and is thus generally considered safe even for pregnant women and children. Acoustic imaging can also be effective for real-time mapping of cavitation events (which occur during ultrasound therapy) but cannot accurately identify soft tissue contours through the skull and other bony structure, which introduces shifts and inaccuracies. MRI is still another imaging modality used to visualize internal tissue. MRI can be used in conjunction with therapeutic (as opposed to imaging) ultrasound to guide the ultrasound focus during therapy as further described below. In brief, MRI involves placing a patient into a homogeneous static magnetic field, thus aligning the spins of hydrogen nuclei in the tissue. Then, by applying a radiofrequency (RF) electromagnetic pulse of the right frequency (the "resonance frequency"), the spins may be flipped, temporarily destroying the alignment and inducing a response signal. Different tissues produce different response signals, resulting in a contrast among these tissues in MR images. Because the resonance frequency and the frequency of the response signal depend on the magnetic field strength, the origin and frequency of the response signal can be controlled by superposing magnetic gradient fields onto the homogeneous field to render the field strength dependent on position. By using time-varying gradient fields, MRI "scans" of the tissue can be obtained. Many MRI protocols utilize time-dependent gradients in two or three mutually perpendicular directions. The relative strengths and timing of the gradient fields and RF pulses are specified in a pulse sequence. Time-dependent magnetic field gradients may be exploited, in combination with the tissue dependence of the MRI response signal, to visualize, for example, a brain tumor, and determine its location relative to the patient's skull. MRI has advantages including multi-planar imaging capability (without moving the patient), high signal-to-noise ratio, high sensitivity to subtle changes in soft tissue morphology and function, and no radiation exposure. But MRI suffers from its sensitivity to patient movement due to the long scan time (typically between 30 minutes to a few hours), lower-resolution images of bony structures, and interference from the operation of other RF devices. MRI is also less effective for real-time cavitation mapping. Because each imaging techniqu