Abstract: A radio frequency coil assembly for an MRI system. A support structure extends between a first end and a second end in a first direction and between an inner surface and an opposite outer surface in a second direction perpendicular to the first direction. The support structure has channels that extend into the support structure in the second direction. An RF coil is configured to transmit and/or receive RF signals. The RF coil is supported by the outer surface of the support structure. The channels are at least partially positioned between the support structure and the RF coil in the first direction and are configured to convey a cooling medium to cool the support structure in use.

Abstract: A method is disclosed to reconstruct multiphase MR images that accurately depict the entire cardiac cycle. A segmented, gradient-recalled-echo sequence is modified to acquire data continuously. Images are retrospectively reconstructed by selecting views from each heartbeat based on cardiac phase rather than the time elapsed from the QRS complex. Cardiac phase is calculated using a model that compensates for beat-to-beat heart rate changes.

Abstract: A method is provided for rapidly measuring change in T.sub.2 * in a region of an MR imaging subject, the method employing a double gradient echo sequence with spiral readout. In this technique, two gradient echoes are acquired after a single RF excitation. A first readout trajectory spirals out from the center of k-space, i.e., k.sub.r =0, to some maximum radius, and then a second readout trajectory spirals back towards the center of k-space. A gradient echo is formed each time a k-space trajectory passes through the center of k-space. The signal intensity of the two echoes allows the calculation of the T.sub.2 * values on a pixel by pixel basis. The ability to measure changes in T.sub.2 * allows measurement of change in perfusion to be quantified.

Abstract: A fast gradient echo, cardiac gated NMR scan is performed by acquiring groups of views during each cardiac cycle. Each group of views is preceded by an accelerator RF pulse and disdaq pulse sequences to improve T.sub.1 contrast and drive spin magnetization rapidly to dynamic equilibrium.

Abstract: Flow encoded NMR pulse sequences are employed to acquire data sets from which a set of angiographic images can be reconstructed depicting blood flow at successive phases during the cardiac cycle. The number of angiographic images is increased by selecting views from adjacent data sets to form interpolated data sets that are employed to reconstruct angiographic images depicting blood flow at cardiac phases between the successive phases.

Abstract: Fast NMR pulse sequences are employed to acquire data in a single breath-hold from which a plurality of cardiac phase images are reconstructed. Signals from fat are suppressed by frequency selective RF inversion pulses applied just prior to each group of fast NMR pulse sequences.

Abstract: Fast NMR pulse sequences are employed to acquire data sets from which a set of images can be reconstructed depicting a patient's heart at successive phases during the cardiac cycle. The number of images is increased by selecting views from adjacent data sets to form interpolated data sets that are employed to reconstruct images depicting the patient's heart at cardiac phases between the successive phases.

Abstract: An NMR system performs a 3DFT scan using a set of steady-state free precession (SSFP) pulse sequences. A contrast preparation pulse sequence precedes each series of SSFP pulse sequences employed to acquire one plane through the three-dimensional space, and it includes a spectrally selective RF inversion pulse tuned to fat or water. The sequence is repeated without any magnetization recovery delays until all the planes have been acquired.

Abstract: T*.sub.2 contrast in images reconstructed from fast NMR pulse sequences is improved by increasing the gradient recalled echo time TE. The pulse repetition time TR is minimized to maintain high temporal resolution by asymmetrically acquiring the echo signal with its peak disposed bear the end of the acquisition window.

Abstract: An NMR system performs a 2DFT or 3DFT scan using a set of steady-state free precession (SSFP) pulse sequences. A contrast preparation pulse sequence precedes each series of SSFP pulse sequences and it includes a spectrally selective RF inversion pulse timed to water to provide T.sub.1 contrast between tissues having relatively long T.sub.1 times, followed by a spectrally selective RF inversion pulse tuned to suppress the signals from fat.

Abstract: An NMR system performs a pulmonary vascular scan comprised of a series of slice acquisition. Each slice acquisition employs a series of fast pulse sequences (GRASS) which are completed in one cardiac cycle. The view order of each slice acquisition is altered such that the low order views are acquired at a desired contrast delay interval after receipt of a cardiac trigger signal.

Abstract: An NMR system acquires a series of spin-echo signals during a scan and these are used to reconstruct an image. The spin-echo signals are partially acquired by locating the data acquisition window asymmetrically with respect to the echo peak. A homodyne reconstruction is employed to fill in the missing data during the image reconstruction.

Abstract: An RF coil assembly for an NMR instrument includes a cylindrical shield which encloses a set of equally spaced linear conductors that surround a central axis. A set of shielded conductors connect to the ends of the linear conductors to form loops. The effective lengths of the loops and the RF signal source which drives the loops are selected to improve the homogeneity of the RF field produced along the central axis.

Abstract: An RF coil assembly for an NMR instrument includes a cylindrical coil surrounded by a cylindrical shield. The annular space between the coil and the shield is filled with a dielectric material having a relative permittivity selected to improve the RF field homogeneity in the radial direction.