Abstract: A system and method for acquiring medical images of a subject includes performing two-dimensional (2D) scan of a subject using a medical imaging system to acquire 2D data from at least two view angles and generating a three-dimensional (3D) model of the subject from the 2D data. The method also includes extracting desired images of the subject from the 3D model. The desired images are at view angles different from the at least two view angles. The method further includes prescribing an imaging study of the subject using the desired images of the subject to control at least one of a signal-to-noise ratio of data acquired using the imaging study or a dose of ionizing radiation delivered to the subject during the imaging study. The method also includes performing the imaging study using the medical imaging system to acquire imaging data from the subject and reconstructing images of the subject from the imaging data.

Abstract: A system and method for acquiring medical images of a subject includes performing two-dimensional (2D) scan of a subject using a medical imaging system to acquire 2D data from at least two view angles and generating a three-dimensional (3D) model of the subject from the 2D data. The method also includes extracting desired images of the subject from the 3D model. The desired images are at view angles different from the at least two view angles. The method further includes prescribing an imaging study of the subject using the desired images of the subject to control at least one of a signal-to-noise ratio of data acquired using the imaging study or a dose of ionizing radiation delivered to the subject during the imaging study. The method also includes performing the imaging study using the medical imaging system to acquire imaging data from the subject and reconstructing images of the subject from the imaging data.

Abstract: An assessment of myocardial viability in a subject is performed by acquiring an MR image which distinguishes infarcted myocardium from normal myocardium. A contrast agent is used and after a waiting period, a cardiac-gated segmented inversion recovery gradient-recalled radial sampling technique is employed to acquire NMR data over a substantial portion of the cardiac cycle. By interleaving the radial sampling patterns, images can be reconstructed over a range of possible TI intervals enabling the optimal TI for maximum contrast to be retrospectively selected.

Abstract: Mask projection views are obtained prior to the arrival of a contrast agent during a dynamic contrast enhanced MRA study. After the arrival of the contrast agent, a set of undersampled contrast enhanced projection views are obtained for each of a plurality of time frames. Corresponding mask projection views are subtracted from the contrast enhanced projection views to provide sparse contrast enhanced projection view sets. A phase contrast scan of a region of interest is performed prior to or after the arrival of the contrast agent. The phase contrast image is used as a composite image in a HYPR reconstruction of the sparse projection view sets to produce first pass contrast enhanced images. Iterative HYPR reconstructions can also be performed to remove venous information from the reconstructed images.

Abstract: Mask projection views are obtained prior to the arrival of a contrast agent during a dynamic contrast enhanced MRA study. After the arrival of the contrast agent, a set of undersampled contrast enhanced projection views are obtained for each of a plurality of time frames. Corresponding mask projection views are subtracted from the contrast enhanced projection views to provide sparse contrast enhanced projection view sets. A phase contrast scan of a region of interest is performed prior to or after the arrival of the contrast agent. The phase contrast image is used as a composite image in a HYPR reconstruction of the sparse projection view sets to produce first pass contrast enhanced images. Iterative HYPR reconstructions can also be performed to remove venous information from the reconstructed images.

Abstract: An RF coil assembly for an MRI system includes a resonator formed by a cylindrical shield and pairs of opposing conductive legs disposed symmetrically around a central axis and extending the axial length of the shield. Drive circuitry for each pair of opposing conductive legs includes a current balun that maintains substantially equal and opposite currents in the two conductive legs. Terminal susceptance elements are used to maintain maximum currents and minimum voltage at the midpoints of the conductive legs. Multinuclear measurements can be made simultaneously at different Larmor frequencies.

Abstract: An RF coil assembly for an MRI system includes a resonator formed by a cylindrical shield and pairs of opposing conductive legs disposed symmetrically around a central axis and extending the axial length of the shield. One set of conductive leg pairs is tuned to operate at the Larmor frequency of 13C and another set is tuned to operate at the Larmor frequency of 1H. Drive circuitry operates the RF coil assembly to produce 1H spin magnetization which is transferred to 13C magnetization by the nuclear overhauser effect and to acquire MR data from the 13C spins. Multinuclear measurements can be made simultaneously at different Larmor frequencies.

Abstract: An RF coil assembly for an MRI system includes a resonator formed by a cylindrical shield and pairs of opposing conductive legs disposed symmetrically around a central axis and extending the axial length of the shield. One set of conductive leg pairs is tuned to operate at the Larmor frequency of 13C and another set is tuned to operate at the Larmor frequency of 1H. Drive circuitry operates the RF coil assembly to produce 1H spin magnetization which is transferred to 13C magnetization by the nuclear overhauser effect and to acquire MR data from the 13C spins. Multinuclear measurements can be made simultaneously at different Larmor frequencies.

Abstract: Localized magnetic fields are measured at frequencies into the microwave (GHz) regime using a conductive loop that is integrated on a vibratable member, such as a cantilever. Driving an alternating current at a first high frequency through the loop produces a high frequency alternating magnetic dipole at the same frequency as the current, with the alternating magnetic dipole normal to and centered within the loop. The alternating magnetic dipole at the center of the loop mixes with a sampled alternating magnetic field at a second high frequency at the center of the loop, resulting in application of a mechanical force to the loop and vibratable member. The vibratable member vibrates when the difference between the frequency of the loop current and the frequency of the sampled alternating magnetic field equals the resonant frequency of the vibratable member.

Abstract: Two images are acquired using a three-dimensional projection reconstruction, SSFP pulse sequence. Different RF phase cycling patterns are used to acquire each image and a fat suppressed water image is produced by combining the two images. Data acquisition efficiency is increased by aquiring k-space data during substantially the entire readout gradient waveform produced during the SSFP pulse sequence.

Abstract: A magnetic resonance angiogram (MRA) is acquired using a contrast enhancement method in which a series of low resolution NMR images are rapidly acquired during a time resolved phase of the examination in which the contrast bolus makes a first pass through the arteries and veins. Additional, high spatial resolution NMR image data is acquired in a subsequent steady-state phase of the examination. The low resolution NMR image is segmented and masked to depict only arteries, and the central k-space region of this data is combined with the peripheral k-space data portion of the high resolution NMR data to produce one or more images.

Abstract: A magnetic resonance angiogram (MRA) is acquired using a contrast enhancement method in which a series of low resolution NMR images are rapidly acquired during a time resolved phase of the examination in which the contrast bolus makes a first pass through the arteries and veins. Additional, high resolution NMR image data is acquired in a subsequent steady-state phase of the examination from which a high resolution NMR image is reconstructed. Segmentation of arteries, veins and background in the high resolution image is performed using information in the low resolution NMR images.

Abstract: A dynamic MRA study of a subject is performed using a 3D echo-planar imaging pulse sequence. Four phase encoding views are acquired for each pulse repetition period (TR) and this enables higher resolution images to be acquired without a reduction of temporal frame rate or a loss of image CNR.

Abstract: A dynamic MRA study of a subject is performed using a 3D fast gradient-recalled echo pulse sequence. The frame rate of the resulting series of reconstructed images is increased by sampling a central region of k-space at a higher rate than the peripheral regions of k-space. Artifacts caused by variations in signal strength as the contrast agent enters the region of interest are reduced by renormalizing the acquired data. 2D image frames are reconstructed using planes passing near the center of k-space to enable the operator to select which 3D data sets should be used to reconstruct diagnostic images.

Abstract: A dynamic MRA study of a subject is performed using a 3D fast gradient-recalled echo pulse sequence. The frame rate of the resulting series of reconstructed images is increased by sampling a central region of k-space at a higher rate than the peripheral regions of k-space. A difference image is produced by subtracting a mask formed by central region k-space sampling from a selected image frame formed by central region and peripheral regions k-space sampling.

Abstract: A dynamic MRA study of a subject is performed using a 3D fast gradient-recalled echo pulse sequence that employs a non-selective RF excitation pulse. The frame rate of the resulting series of reconstructed images is increased by sampling a central region of k-space at a higher rate than the peripheral regions of k-space. The acquisition is gated using a cardiac trigger signal and the central region of k-space is acquired during diastole and the peripheral regions of k-space are acquired during systole. Image frames are reconstructed at each sampling of the central k-space region using the temporally nearest samples from the peripheral k-space regions. Two of the image frames are subtracted to form an MR angiogram.

Abstract: A dynamic MRA study of a subject is performed using a 3D fast gradient-recalled echo pulse sequence. The frame rate of the resulting series of reconstructed images is increased by sampling a central region of k-space at a higher rate than the peripheral regions of k-space. Image frames are reconstructed at each sampling of the central k-space region using the temporally nearest samples from the peripheral k-space regions.

Abstract: A local coil for use with an MRI system to acquire images of a patient's legs includes a vertically disposed central coil positioned between the legs, and a pair of horizontally disposed flange coils positioned above and below the legs. In one embodiment of the central coil is a phased array of two coils, and the four coils are connected to the respective inputs of a four channel receiver, and in a second embodiment, the signals from the three coils are combined before application to the input of a single-channel receiver.

Abstract: An angiogram is produced using NMR fast pulse sequences in which the views are acquired in shots preceded by a preparatory pulse sequence. Each shot is acquired twice with differing preparatory pulse sequences and the resulting NMR data is subtracted to null the stationary tissues in the reconstructed image.

Abstract: Counter Rotating Current (CRC) pairs of loop-gap resonators are combined with planar pairs of loop-gap resonators to form networks of NMR local coils. A first embodiment is a quadrature probe in which a planar pair is sandwiched between the loop-gap resonators of the CRC pair. In a plurality of other embodiments, CRC pairs, planar pairs, and other types of local coils are arranged adjacent to one another to form networks of NMR local coils with an enlarged net region of sensitivity.