Abstract: A device for positioning an energy-generating transducer probe a movement unit. The transducer probe may be configured for heat treatment of biological tissues and emits energy in one aiming direction which is located in an aiming plane. The movement unit is configured to alter the position of the transducer probe and, consequently, the aiming direction in the aiming plane around a target zone within the aiming plane.

Abstract: In order to decrease collateral heating of ribs and tissue surrounding the ribs in a patient during high-intensity focused ultrasound (HIFU) therapy, shielding material may be positioned on or adjacent to an external surface of the patient and aligned with ribs to be protected using a magnetic resonance imaging (MRI) system. The MRI system may be used to image the shielding material and the ribs to be protected, and an error of alignment between the ribs to be protected and the shielding material may be determined based on the images. The shielding or masking material may be repositioned based on the determined error of alignment, images of the shielding material and the ribs to be protected may be reacquired, and the error of alignment may be redetermined based on the reacquired images until the shielding material is aligned with the ribs to be protected.

Abstract: An RF active device, immersed in liquid medium, for use in a magnetic resonance system is provided with an RF shield formed of electrically conductive material and having an interior cavity configured to receive the RF active device therein. The RF shield substantially precludes coupling between the active device, and any coupling medium that is employed, and the transmission and reception coils of the magnetic resonance system.

Abstract: An ultrasound transducer for use in a magnetic resonance system is provided with an RF shield formed of electrically conductive material and having an interior cavity configured to receive the ultrasound transducer therein. The RF shield substantially precludes coupling between the ultrasound transducer, and any coupling medium that is employed, and the transmission and reception coils of the magnetic resonance system.

Abstract: In a method or system for magnetic resonance imaging based temperature monitoring for real-time feedback to a physician for a cryoablation therapy of a lesion which creates an ice ball of the lesion to induce cell death, the magnetic resonance imaging system, using proton resonance frequency imaging, obtains a real-time temperature image of the ice ball of the lesion undergoing the cryoablation therapy and the adjacent surrounding tissue. By use of an algorithm, correcting temperature errors at a border of the ice ball are corrected in the real-time image, the temperature error correction correcting susceptibility contrast errors caused by a distortion of the local magnetic field at the border of the ice ball.

Abstract: In a method to determine a background phase in phase values of a phase image data set that is acquired from an examination subject, wherein the background phase is determined in a partial region of the phase image data set, the phase image data set of the examination subject is acquired, and a substantially closed, planar contour is established in the phase image data set around the partial region, the planar contour having a contour area with a width of at least one pixel of the phase image data set. The phase values in the partial region are determined with the assumption that the spatial curve of the background phase is a harmonic or quasi-harmonic function, the phase values of the pixels in the partial region being determined based on the phase values in the planar contour.

Abstract: In a method for temperature control in MR-guided administration of ultrasound, ultrasound therapy is administered to a patient at an in vivo site by emitting focused ultrasound into the site at multiple foci with a multi-focus ultrasound therapy device. The temperature is monitored in a localized region of an examination subject in which the site is located during the therapy in real-time by MR thermometry. From the MR thermometry, characteristics of the temperature distribution in the monitored region of the examination subject are automatically identified. Temperature control is implemented by regulating the energy output of the ultrasound therapy device, according to a rapidly converging master equation.

Abstract: In a method and magnetic resonance (MR) apparatus for implementing an MR-guided procedure, an MR-compatible digital camera is placed in the patient receiving opening of the MR data acquisition unit that is operated to acquire MR data for reconstructing images that are used to guide the MR-guided intervention. The digital camera is operated to obtain digital images of the exterior of the patient, from which motion of the patient is detectable. The images are analyzed in a processor to identify therefrom the motion of the patient and the result of the analysis is represented as a processor output that is used to control the timing, with respect to the motion of the examination subject, of the occurrence of at least one event in the MR-guided procedure. One important application is respiratory gating/triggering of HIFU sonication for the treatment of moving organs.

Abstract: The focus of a focused ultrasound system is calibrated with respect to a frame-of-reference, such as that of a magnetic resonance system, by selectively activating only specific regions of the ultrasound transducer of the ultrasound system, thereby altering the shape of the focus. The focal shape is selectively modified in shape and positioned in successive steps of a calibration procedure, while moving the focus through successive localizers of the frame-of-reference. The parameters for operating the ultrasound system when the calibration procedure is completed are stored as parameters that accurately position the focus of the ultrasound system with respect to the frame-of-reference.

Abstract: In order to decrease collateral heating of ribs and tissue surrounding the ribs in a patient during high-intensity focused ultrasound (HIFU) therapy, shielding material may be positioned on or adjacent to an external surface of the patient and aligned with ribs to be protected using a magnetic resonance imaging (MRI) system. The MRI system may be used to image the shielding material and the ribs to be protected, and an error of alignment between the ribs to be protected and the shielding material may be determined based on the images. The shielding or masking material may be repositioned based on the determined error of alignment, images of the shielding material and the ribs to be protected may be reacquired, and the error of alignment may be redetermined based on the reacquired images until the shielding material is aligned with the ribs to be protected.

Abstract: In a method and an apparatus for magnetic resonance guided high intensity focused ultrasound (HIFU), precise localization of the focal point of the HIFU is determined by imaging an examination subject in parallel with GRE sequences that respectively include a positive monopolar gradient pulse and a negative monopolar gradient pulse, that respectively encode the acoustic radiation force (ARF)-induced phase shift that is induced by the simultaneous activation of HIFU during the sequences. A GRE phase image is reconstructed from each acquisition sequence, and a difference image is formed between the two GRE phase images, from which the HIFU focal point is determined. An average image is formed of the two GRE phase images from which PRFS temperature map is determined simultaneously to ARFI map.

Abstract: In a method for temperature control in MR-guided administration of ultrasound, ultrasound therapy is administered to a patient at an in vivo site by emitting focused ultrasound into the site at multiple foci with a multi-focus ultrasound therapy device. The temperature is monitored in a localized region of an examination subject in which the site is located firing said therapy in real-time by MR thermometry. From the MR thermometry, characteristics of the temperature distribution in the monitored region of the examination subject are automatically identified. Temperature control is implemented by regulating the energy output of the ultrasound therapy device, according to a rapidly converging master equation.

Abstract: In order to reduce reflection and heating of a high intensity focused ultrasound (HIFU) beam following a region of interest in tissue to which an HIFU beam was administered, at least two layers of aquasonic gel are applied at a tissue/air interface following the region of interest and the focus in a direction of propagation of the HIFU beam. A first of the two aquasonic gel layers is a foamed aquasonic gel layer, and a second of the two layers is substantially bubble-free aquasonic gel. The layer of foamed aquasonic gel is placed directly adjacent the tissue/air interface, and the layer of substantially bubble-free aquasonic gel is placed over the layer of foamed aquasonic gel, at a side thereof facing away from the tissue/air interface.

Abstract: An assembly for heat treating an area of biological tissue, including an energy generating device for supplying energy to a focal point in said area, a device for measuring the spatial temperature distribution in said area, and a control unit for controlling the movement of the focal point along a predetermined path to give a spatial temperature distribution consistent with a pre-sent distribution, characterized in that, as the focal point moves along the path, the control unit controls the distribution of the energy provided by the generating device depending on the measured temperature distribution and the pre-set distribution, in accordance with a control law including a proportional-integral-derivative term.

Abstract: In a method or system for magnetic resonance imaging based temperature monitoring for real-time feedback to a physician for a cryoablation therapy of a lesion which creates an ice ball of the lesion to induce cell death, the magnetic resonance imaging system, using proton resonance frequency imaging, obtains a real-time temperature image of the ice ball of the lesion undergoing the cryoablation therapy and the adjacent surrounding tissue. By use of an algorithm, correcting temperature errors at a border of the ice ball are corrected in the real-time image, the temperature error correction correcting susceptibility contrast errors caused by a distortion of the local magnetic field at the border of the ice ball.

Abstract: An ultrasound transducer for use in a magnetic resonance system is provided with an RF shield formed of electrically conductive material and having an interior cavity configured to receive the ultrasound transducer therein. The RF shield substantially precludes coupling between the ultrasound transducer, and any coupling medium that is employed, and the transmission and reception coils of the magnetic resonance system.

Abstract: In a method and system for administering a dispersible medical agent to a subject, a volume of medical agent is delivered in vivo to a subject in a substantially non-dispersed state, at a localized site in tissue of the subject. Contemporaneously with administration of the medical agent to the localized site, energy from an energy source is introduced into only adjacent tissue surrounding the localized site. The energy produces a cellular modification of the adjacent tissue that makes the adjacent tissue substantially impermeable to passage of the medical agent therethrough, so the medical agent is encapsulated and is prevented from dispersing into tissue outside of the encapsulation.

Abstract: In order to reduce reflection and heating of a high intensity focused ultrasound (HIFU) beam following a region of interest in tissue to which an HIFU beam was administered, at least two layers of aquasonic gel are applied at a tissue/air interface following the region of interest and the focus in a direction of propagation of the HIFU beam. A first of the two aquasonic gel layers is a foamed aquasonic gel layer, and a second of the two layers is substantially bubble-free aquasonic gel. The layer of foamed aquasonic gel is placed directly adjacent the tissue/air interface, and the layer of substantially bubble-free aquasonic gel is placed over the layer of foamed aquasonic gel, at a side thereof facing away from the tissue/air interface.

Abstract: In a method and an apparatus for magnetic resonance guided high intensity focused ultrasound (HIFU), precise localization of the focal point of the HIFU is determined by imaging an examination subject in parallel with GRE sequences that respectively include a positive monopolar gradient pulse and a negative monopolar gradient pulse, that respectively encode the acoustic radiation force (ARF)-induced phase shift that is induced by the simultaneous activation of HIFU during the sequences. A GRE phase image is reconstructed from each acquisition sequence, and a difference image is formed between the two GRE phase images, from which the HIFU focal point is determined. An average image is formed of the two GRE phase images from which PRFS temperature map is determined simultaneously to ARFI map.

Abstract: In a method to determine a background phase in phase values of a phase image data set that is acquired from an examination subject, wherein the background phase is determined in a partial region of the phase image data set, the phase image data set of the examination subject is acquired, and a substantially closed, planar contour is established in the phase image data set around the partial region, the planar contour having a contour area with a width of at least one pixel of the phase image data set. The phase values in the partial region are determined with the assumption that the spatial curve of the background phase is a harmonic or quasi-harmonic function, the phase values of the pixels in the partial region being determined based on the phase values in the planar contour.