Abstract: A method of producing volume renderings from magnetic resonance image data in real time with user interactivity. The method comprises collecting raw magnetic resonance image (MRI) data representative of shapes within an image volume; transferring the raw MRI data to a computer; and continuously producing volume renderings from the raw MRI data in real time with respect to the act of collecting raw MRI data representative of shapes within the image volume.

Abstract: A method of producing volume renderings from magnetic resonance image data in real time with user interactivity. The method comprises collecting raw magnetic resonance image (MRI) data representative of shapes within an image volume; transferring the raw MRI data to a computer; and continuously producing volume renderings from the raw MRI data in real time with respect to the act of collecting raw MRI data representative of shapes within the image volume.

Abstract: A system and method for using magnetic resonance imaging to increase the accuracy of electrophysiologic procedures includes an invasive combined electrophysiology and imaging antenna catheter which includes an RF antenna for receiving magnetic resonance signals and diagnostic electrodes for receiving electrical potentials. The combined electrophysiology and imaging antenna catheter is used in combination with a magnetic resonance imaging scanner to guide and provide visualization during electrophysiologic diagnostic or therapeutic procedures, such as ablation of cardiac arrhythmias. The combined electrophysiology and imaging antenna catheter may further include an ablation tip, and be used as an intracardiac device to deliver energy to selected areas of tissue and visualize the resulting ablation lesions. The antenna utilized in the combined electrophysiology and imaging catheter for receiving MR signals is preferably of the coaxial or “loopless” type.

Abstract: A method of producing volume renderings from magnetic resonance image data in real time with user interactivity. The method comprises collecting raw magnetic resonance image (MRI) data representative of shapes within an image volume; transferring the raw MRI data to a computer; and continuously producing volume renderings from the raw MRI data in real time with respect to the act of collecting raw MRI data representative of shapes within the image volume.

Abstract: A method for fat-suppressed imaging is disclosed. Such a method may include storing a first spectral component of an echo signal formed at TR/2 from a sample, suppressing a second spectral component of the echo signal at TR/2, re-exciting the stored spectral component after suppressing the second spectral component, and producing an image of the sample based on the re-excited stored spectral component.

Abstract: A system and method for using magnetic resonance imaging to increase the accuracy of electrophysiologic procedures is disclosed. The system in its preferred embodiment provides an invasive combined electrophysiology and imaging antenna catheter which includes an RF antenna for receiving magnetic resonance signals and diagnostic electrodes for receiving electrical potentials. The combined electrophysiology and imaging antenna catheter is used in combination with a magnetic resonance imaging scanner to guide and provide visualization during electrophysiologic diagnostic or therapeutic procedures. The invention further provides a system for eliminating the pickup of RF energy in which intracardiac wires are detuned by filtering so that they become very inefficient antennas. An RF filtering system is provided for suppressing the MR imaging signal while not attenuating the RF ablative current. Steering means may be provided for steering the invasive catheter under MR guidance.

Abstract: A method of performing brain therapy may include placing a subject in a main magnetic field, introducing into the subject's brain a combination imaging and therapeutic probe, the probe including a magnetic resonance imaging antenna and an electrical energy application element, acquiring a first magnetic resonance image from the antenna of the combination probe, acquiring a second magnetic resonance image from a surface coil, combining the first and second magnetic resonance images to produce a composite image, positioning the combination probe within the brain with guidance from at least one of the images, and delivering electrical energy to the brain from the electrical energy application element of the combination probe thus positioned.

Abstract: A T2 preparation sequence uses a segmented BIR-4 adiabatic pulse with two substantially equal delays and is insensitive to B1 field variations and can simultaneously suppress fat signals with low specific absorption rate (SAR). An adiabatic reverse half passage pulse is applied followed by a predetermined delay. An adiabatic full passage pulse is applied followed by a substantially equal delay, followed by an adiabatic half passage pulse. Fat signal suppression is achieved by increasing or decreasing either the first delay or the second delay.

Abstract: Phase contrast magnetic resonance images are produced using interleaved spiral k-space scanning with a bipolar phase contrast gradient. Spiral scanning is configured so that acquisition impulse response defines a central alias free portion in a partial field of view, and signal acquisition is arranged so that moving spins are contained with this central alias free portion. First and second signals are acquired with alternate phase encodings, and a complex difference of the acquired signals is obtained. The complex difference is substantially free of aliasing artifacts within the central portion.

Abstract: A method that exploits the intrinsic selectivity of steady-state free precession (SSFP) to perform spectral suppression is disclosed. Such a method avoids the need to incorporate additional spectrally selective pulse sequence elements. The scheme is based on breaking the FISP imaging sequence into short trains having, for example, 8–64 RF pulses. At the moment of echo formation (i.e., TE=TR/2) after the last full RF pulse of the train, water signal is z-stored. Residual transverse magnetization, which include isochromats phase-opposed to the on-resonance water, is gradient crushed and RF spoiled. The stored magnetization is subsequently re-excited with little disturbance to the on-resonance steady-state water signal. The additional time required to perform the steady-state interruption is typically as little as a single TR, minimally affecting the efficiency of the imaging process.

Abstract: A system and method for using magnetic resonance imaging to increase the accuracy of electrophysiologic procedures is disclosed. The system in its preferred embodiment provides an invasive combined electrophysiology and imaging antenna catheter which includes an RF antenna for receiving magnetic resonance signals and diagnostic electrodes for receiving electrical potentials. The combined electrophysiology and imaging antenna catheter is used in combination with a magnetic resonance imaging scanner to guide and provide visualization during electrophysiologic diagnostic or therapeutic procedures. The invention is particularly applicable to catheter ablation, e.g., ablation of atrial fibrillation.

Abstract: A method of performing brain therapy may include placing a subject in a main magnetic field, introducing into the subject's brain a combination imaging and therapeutic probe, the probe including a magnetic resonance imaging antenna and an electrical energy application element, acquiring a first magnetic resonance image from the antenna of the combination probe, acquiring a second magnetic resonance image from a surface coil, combining the first and second magnetic resonance images to produce a composite image, positioning the combination probe within the brain with guidance from at least one of the images, and delivering electrical energy to the brain from the electrical energy application element of the combination probe thus positioned.

Abstract: A system and method for using magnetic resonance imaging to increase the accuracy of electrophysiologic procedures is disclosed. The system in its preferred embodiment provides an invasive combined electrophysiology and imaging antenna catheter which includes an RF antenna for receiving magnetic resonance signals and diagnostic electrodes for receiving electrical potentials. The combined electrophysiology and imaging antenna catheter is used in combination with a magnetic resonance imaging scanner to guide and provide visualization during electrophysiologic diagnostic or therapeutic procedures. The invention is particularly applicable to catheter ablation, e.g., ablation of atrial fibrillation.

Abstract: A system and method for using magnetic resonance imaging to increase the accuracy of electrophysiologic procedures is disclosed. The system in its preferred embodiment provides an invasive combined electrophysiology and imaging antenna catheter which includes an RF antenna for receiving magnetic resonance signals and diagnostic electrodes for receiving electrical potentials. The combined electrophysiology and imaging antenna catheter is used in combination with a magnetic resonance imaging scanner to guide and provide visualization during electrophysiologic diagnostic or therapeutic procedures. The invention is particularly applicable to catheter ablation, e.g., ablation of atrial fibrillation.

Abstract: A method of producing volume renderings from magnetic resonance image data in real time with user interactivity. The method comprises collecting raw magnetic resonance image (MRI) data representative of shapes within an image volume; transferring the raw MRI data to a computer; and continuously producing volume renderings from the raw MRI data in real time with respect to the act of collecting raw MRI data representative of shapes within the image volume.

Abstract: A ghost artifact cancellation technique is disclosed. Phased array combining is used to cancel ghosts caused by a variety of distortion mechanisms, including space-variant distortions, such as local flow or off-resonance. The technique uses a constrained optimization that optimizes signal-to-noise ratio (SNR) subject to the constraint of nulling ghost artifacts at known locations. In one aspect multi-coil, k-space data is passed through a converter to convert the k-space data to image domain. After the conversion, the images contain ghost artifacts. The images are then passed through one or more phased array combiners. Each phased array combiner separates the superimposed ghosts to produce an image without ghosts. These images may then be aligned by means of shifting and combined by a variety of means to improve the final image quality. In another aspect, the phase encode order is varied in time to produce ghosts with time varying phase.

Abstract: An apparatus and method for accelerating magnetic resonance imaging by decreasing the number of sequential phase encodes (undersampling). Image reconstruction of undersampled k-space data can cause ghost artifacts to be produced in the resulting sequence of images. A combination of temporal and spatial filters are used to substantially suppress the ghost artifacts. Additionally, the spatial filter receives spatial filter coefficients used in the filtering process. The spatial filter coefficients are adaptively or dynamically generated so that the coefficients are provided to the spatial filter while generating the sequence of images.

Abstract: Navigator signals are acquired during a cardiac gated MRI scan to measure the position and velocity components of respiratory motion. Acquired cardiac image views are discarded and/or corrected based on the measurement of the positional and velocity components of respiratory motion to reduce motion artifacts. In one embodiment the navigator pulse sequence includes velocity encoding gradient, and in a second embodiment, velocity is determined by measuring the change in diaphragm position between successive navigator pulse sequences.

Abstract: The invention provides a method of magnetic resonance imaging. A magnetic resonance imaging apparatus having a plurality of gradient axes is employed. A plurality of imaging planes are employed with respect to the gradient axes. A plurality of gradient referencing pre-scans are executed for the imaging planes to provide a plurality of calibration correction values for the imaging planes. A specimen is employed with respect to the gradient axes. An imaging plane is selected with respect to the specimen, and a main magnetic field is established with respect to the specimen. Radio frequency pulses are applied to the specimen to produce magnetic resonance signals. The calibration correction values for the selected imaging plane are employed to adjust a plurality of gradient waveforms. The gradient waveforms are output as a plurality of magnetic field gradients with respect to the gradient axes.

Abstract: A method of magnetic resonance imaging of myocardial motion includes positioning a portion of a patient such as a patient's heart within a main magnetic field and employing a plurality of RF signals to establish a plurality of parallel plane tags through the portion. In imaging heart motion, a first minimum spacing between adjacent tags is employed in a region where the tags will decrease their separation over systole and a second initial tag separation will be employed for portions wherein the tags increase their separation over systole. The method facilitates simultaneous imaging of both such motions. Fourier coefficients may be employed in establishing the generally parallel tags which may be positioned generally symmetrically about a central tag.