Abstract: A Faraday cage assembly for use with a Magnetic Resonance (MR) Imaging scanner is deployed inside the MR scanner room. The Faraday cage assembly is configured to accept accessory medical equipment which is desired to be attached to the patient during scanning. Accessory medical equipment can include patient monitoring systems, injector pumps, and intravenous (IV) poles with infusion pumps. Once the accessory medical equipment is placed inside the Faraday cage, radiofrequency (RF) interference emitted by the accessory medical equipment is contained within the cage and cannot significantly degrade MR image quality. The cage may permit non-MR compatible accessory equipment such as infusion pumps to be used without modification or reconfiguration during MR scanning.

Abstract: An instrument guide apparatus for use with a surgical or other guided intervention of a patient utilizing a guided instrument is disclosed. The instrument guide apparatus includes at least two line lasers mounted above the patient and generating intersecting planar laser lines along an instrument axis of entry in three-dimensional space above the patient. In an embodiment, the instrument axis of entry in three dimensional space above the patient is received from an imaging apparatus imaging the patient's body at least along a portion of the instrument's axis of entry into the patient. In an embodiment, the instrument axis of entry in three-dimensional space above the patient is a line-of-site for a camera mounted above the patient and controlled by the imaging apparatus.

Abstract: Systems and methods for debulking visceral fat within a subject, include: providing a focused ultrasound transducer configured to focus ultrasonic power at a focal spot; positioning the focused ultrasound transducer with respect to the subject so that the focused ultrasound transducer is enabled to transfer ultrasonic power into the subject; locating the focal spot of the focused ultrasound transducer with respect to at least one target region containing visceral fat within the subject; and debulking visceral fat within the target region by applying ultrasonic energy from the focused ultrasound transducer with sufficient power to cause the death of visceral fat tissue within the target region.

Abstract: Techniques for correcting temperature measurement in MR thermometry are disclosed. In particular, phase shifts that arise from factors other than temperature changes are detected, facilitating correction of temperature measurements.

Abstract: A magnetic resonance system has been developed for actively tracking the three-dimensional positions of numerous coils provided on one or more medical devices. One particular example of a novel magnetic resonance system of the present invention is capable of simultaneously tracking the positions of up to 32 coils or more, which may be provided on the medical device(s). As an example, catheter devices having a large number of independent tracking coils have been constructed, in which each coil has a direct connection to one at least the same number of receivers in the magnetic resonance system. Accordingly, physicians can obtain real-time visualization of the positions of medical devices using a magnetic resonance system, with sufficient frame-rates to guide the manipulation of the medical devices within the body of a patient. The medical devices may include catheters and guidewires.

Abstract: A magnetic resonance imaging method of in-vivo measurement for renal hemodynamic functions by obtaining renal function images in the presence of an intravascular contrast agent with a modified inversion recovery pulse sequence imaging technique, determining the renal artery and renal vein blood longitudinal relaxation times from the data derived from the images and employing these times to arrive at the filtration fraction.

Abstract: A magnetic resonance (MR) active invasive device system employs a small, high-field polarizing magnet, and a large, possibly low-field magnetic resonance (MR) imaging magnet for the purpose of generating MR angiograms of selected blood vessels. A subject is positioned in a large MR imaging magnet. A catheter is inserted into the patient at or near the root of a vessel tree to be imaged. A fluid, intended to be used as a contrast agent is first cooled and frozen, and then passed through the small high-field polarizing magnet where it becomes highly polarized. The frozen fluid is then heated and melted to physiologic temperatures and introduced into the subject through the catheter. Radiofrequency (RF) pulses and magnetic field gradients are then applied to the patient as in conventional MR imaging.

Abstract: A magnetic resonance (MR) active invasive device system employs a small, high-field polarizing magnet, and a large magnetic resonance (MR) imaging magnet for the purpose of generating MR images of selected body cavities. A subject is positioned in a large low-field MR imaging magnet. A substance, intended to be used as a contrast agent is first cooled, and then passed through the small high-field polarizing magnet where it becomes highly polarized. The substance is then heated to physiologic temperatures, vaporized, and introduced into the subject through a transfer conduit as a vapor. Radiofrequency (RF) pulses and magnetic field gradients are then applied to the patient as in conventional MR imaging. Since the vapor is highly polarized, it can be imaged even though it has a much lower density than the surrounding tissue.

Abstract: A magnetic resonance (MR) active invasive device system employs a small, high-field polarizing magnet, and a large low-field magnetic resonance (MR) imaging magnet for the purpose of generating MR angiograms of selected blood vessels. A subject is positioned in a large low-field MR imaging magnet. A catheter is inserted into the patient at or near the root of a vessel tree desired to be imaged. A hydrogen gas is first cooled and condensed into a liquid state, and then passed through the small high-field polarizing magnet where it becomes highly polarized. A contrast fluid is then made by chemically combining the polarized hydrogen with oxygen to obtain highly polarized water. The water is then heated to physiologic temperatures and, if desired, made more physiologically compatible with the addition of substances such as salts. The physiologically conditioned polarized fluid is then introduced into the subject through the catheter.

Abstract: A magnetic resonance (MR) active invasive device system employs a small, high-field polarizing magnet having a toroidal geometry, and a large low-field magnetic resonance (MR) imaging magnet for the purpose of generating MR angiograms of selected blood vessels. A subject is positioned in a large low-field MR imaging magnet. A catheter is inserted into the patient at or near the root of a vessel tree to be imaged. A fluid, intended to be used as a contrast agent is first passed through the small high-field polarizing magnet, causing a great deal of net longitudinal magnetization to be produced in the fluid. The fluid is then introduced into the subject through the catheter. Radiofrequency (RF) pulses and magnetic field gradients are then applied to the patient as in conventional MR imaging.

Abstract: A magnetic resonance (MR) active invasive device system for imaging blood vessels employs an integrated polarizing and imaging magnet which is comprised of a small, high-field polarizing magnet whose flux return path is routed through pole structures to produce a large substantially uniform low-field magnetic region suitable for low-field magnetic resonance imaging. A subject is positioned in the uniform low-field region. A catheter is inserted into the patient at or near the root of a vessel tree to be imaged. A fluid, intended to be used as a contrast agent is first passed through the small high-field polarizing magnet, creating a large net longitudinal magnetization in the fluid. The fluid is then introduced into the subject is through the catheter. Radiofrequency (RF) pulses and magnetic field gradients are then applied to the patient as in conventional MR imaging.

Abstract: A tracking system monitors the position of a device within a subject and superimposes a graphic symbol on a diagnostic image of the subject. Registration of the tracked location with the diagnostic image is maintained in the presence of subject motion by monitoring subject motion and adjusting the display to compensate for subject motion. Motion monitoring can be performed with ultrasonic, optical or mechanical methods. The display can be adjusted by modifying the displayed location of the device or it can be adjusted by translating, rotating or distorting the diagnostic image.

Abstract: A multi-planar imaging method employs magnetic resonance to detect image data from multiple planes within a subject. Data from each plane are detected in response to the same readout gradient and are simultaneously detected. The image planes can be arbitrarily oriented with respect to each other and with respect to the readout and phase-encoding image formation magnetic field gradient pulses if desired. Overlap of image data from each of the excited image planes in the acquired image is prevented by employing a thick refocusing slab oriented orthogonal to the readout and phase-encoding directions, or by choosing planes which intersect outside the subject's anatomy.

Abstract: A multi-planar imaging method employs magnetic resonance to detect image data from multiple planes within a subject. Data from each plane are detected in response to the same readout gradient and are simultaneously detected. The image planes can be arbitrarily oriented with respect to each other and with respect to the readout and phase-encoding image formation magnetic field gradient pulses if desired. Overlap of image data from each of the excited image planes in the acquired image is prevented by modulating the phase of each RF excitation pulse in concert with the amplitude of the phase-encoding gradient pulse to cause the image data from each excitation plane to be displaced by a unique amount in the phase-encoding direction.

Abstract: A magnetic resonance system employs a sequence of radio frequency pulses and magnetic field gradients to generate a flow-compensated image of a selected portion of a sample. Flow-compensation is performed with an oscillating readout gradient waveform which is comprised of two components. The first component is a constant amplitude gradient waveform whose amplitude is determined by the desired field-of-view and the bandwidth of the imaging system. The second component is an oscillating waveform whose amplitude, frequency and phase are chosen to obtain the desired degree of flow-compensation. The frequency of the oscillating waveform is typically chosen to match the sampling frequency of the imaging system. In effect, each acquired data point is preceded by the application of a bi-polar magnetic field gradient pulse which causes a phase shift in the acquired signal which is proportional to nuclear spin velocity.

Abstract: An interactive display system superimposes images of internal structures on a semi-transparent screen through which a surgeon views a patient during a medical procedure. The superimposed image is derived from image data obtained with an imaging system. An invasive device is also tracked and displayed on the semi-transparent screen. A ray extending through the invasive device can also be displayed which shows the intended path of the invasive device. The image is registered with the surgeon's view of the patient and displayed in real-time during a medical procedure. This allows the surgeon to view internal and external structures, the relation between them, the proposed path of the invasive device, and adjust the procedure accordingly. A second embodiment employs stereoscopic viewing methods to provide three-dimensional representations of the radiological images superimposed on the semi-transparent screen through which the surgeon views the patient.

Abstract: An elasticity imaging method uses magnetic resonance to detect the distribution of eternally induced velocities within a subject. Distributions am measured responsive to at least two different field-of-views. Differences of the velocity distribution obtained with one field-of-view and the second field-of-view are computed to give a component of stress. The method can be used to obtain velocity measurements in any of three mutually orthogonal directions responsive to field-of-view shifts in as many as three mutually orthogonal directions to give a total of nine stress components. Data for each component can be acquired independently or data acquisition can be multiplexed to reduce data acquisition requirements.

Abstract: A method of simultaneously imaging multiple components of velocity of moving materials within a subject employs magnetic resonance. Velocity encoding is performed by computing differences of data obtained with modulated motion encoding magnetic field gradient pulses. Distributions of velocity are measured responsive to a motion sensitive phase encoding gradient pulse.

Abstract: A magnetic resonance (MR) active invasive device system employs a small, high-field polarizing magnet, and a large low-field magnetic resonance (MR) imaging magnet for the purpose of generating MR angiograms of selected blood vessels. A subject is positioned in a large low-field MR imaging magnet. A catheter in inserted into the patient at or near the root of a vessel tree desired to be imaged. A fluid, intended to be used as a contrast agent is first passed through the small high-field polarizing magnet, causing a great deal of net longitudinal magnetization to be produced in the fluid. The fluid is then introduced into the subject through the catheter. Radiofrequency (RF) pulses and magnetic field gradients are then applied to the patient as in conventional MR imaging. Since the fluid has a larger longitudinal magnetization, before the MR imaging sequence, the fluid produces a much larger MR response signal than other tissue resulting in the vessel tree being imaged with excellent contrast.

Abstract: A motion imaging method uses magnetic resonance to detect acceleration, and an velocity distribution within moving materials in a subject. Acceleration encoding is performed by computing differences of data obtained with modulated motion-encoding magnetic field gradient pulses. Distributions of velocity are measured responsive to a motion sensitive phase-encoding gradient pulse.