Fonar Corporation

Rajendra K Shenoy

Raymond V Damadian

Jan V Votruba

Jevan Damadian

David Hertz

Terry Morrone

Robert B Wolf

Anthony J Giambalvo

Sudhir Moolky

Through modification of the phase-encoding gradient, a method and apparatus increases the effectiveness of a Magnetic Resonance Imaging (MRI) device by decreasing scan time without noticeably decreasing the signal-to-noise ratio. In an MRI device, a patient is subjected to a constant magnetic field, and then radio frequency (RF) pulses are used to excite the nuclei in the patient's body. The nuclei release a corresponding RF signal as the nuclei relax, which can be measured and mapped into a visual display. The RF pulses used to excite the nuclei in the body cooperate with a slice select gradient and a phase-encoding gradient. When the phase-encoding gradient is indexed and prioritized according to contribution to image quality, then phase-encoding values with little or no contribution to image quality need not be acquired but may be replaced with randomized system noise, thereby decreasing total scan time without reducing the signal-to-noise ratio.

Magnetic resonance imaging using adaptive phase encoding gradient

An NMR imaging process includes subjecting an imaging object to a uniform polarizing magnetic field. Orthogonal magnetic field gradients are applied to the imaging object. RF energy is applied to the imaging object. The RF energy includes a plurality of angular precession frequencies simultaneously applied to correspond to a respective plurality of selected slices of the imaging object. A corresponding plurality of nuclear magnetic resonance signals emitted by the imaging object are simultaneously detected. The nuclear magnetic resonance signals are processed to provide diagnostic information related to individual ones of the plurality of selected slices. In this way, multiple slices are excited and sampled simultaneously. The RF energy can be applied by applying RF energy to the imaging object according to a fast-spin echo technique and subsequently applying RF energy to the imaging object according to a driven equilibrium technique.

Driven equilibrium and fast-spin echo scanning

The method includes positioning a patient within a receiving space of a stand-up MRI apparatus and imaging the region of interest of the patient while the patient moves the region of interest. Further in accordance with the method the patient may be positioned such that the patient faces a pole face of a magnet of the MRI apparatus. The apparatus comprises a patient support which allows imaging of a patient's spine with a gravitational load on the spinal system.

Method for lateral motion magnetic resonance imaging

An NMR imaging process utilizes application of both a driven equilibrium technique and a fast-spin echo technique to acquire image. The fast-spin echo technique is a multiecho NMR imaging sequence, where different echoes are encoded differently to fill the (k, k) space at a speed of 1/n of the single echo speed, where n is the number of echoes in the multiecho sequence. During this echo train, a 90-degree RF pulse applied with proper phase at the center of any echo turns the magnetization back in the direction of the static magnetic field. Within a short waiting time after the 90-degree RF pulse, the spins are ready to be excited again. The multi-echo sequence has one 90-degree RF pulse at the beginning, followed by a series of n 180-degree RF pulses, followed by n echoes. A second 90-degree RF pulse is turned on exactly at the center of the nth echo, which returns all the magnetization left at this time to the static field direction. Only one frequency is used for excitation in acquiring the NMR signal in the single slice mode. Gradients are adjusted for oblique scanning. In the multislice acquisition mode, RF phases of different slices are different from one another and the final images can be constructed either by sharing the kspace or by using a transform process to separate the slices.

An NMR imaging process utilizes application of both a driven equilibrium technique and a fast-spin echo technique to acquire image. The fast-spin echo technique is a multiecho NMR imaging sequence, where different echoes are encoded differently to fill the (k, k) space at a speed of 1/n of the single echo speed, where n is the number of echoes in the multiecho sequence. During this echo train, a 90-degree RF pulse applied with proper phase at the center of any echo turns the magnetization back in the direction of the static magnetic field. Within a short waiting time after the 90-degree RF pulse, the spins are ready to be excited again. The multi-echo sequence has one 90-degree RF pulse at the beginning, followed by a series of n 180-degree RF pulses, followed by n echoes. A second 90-degree RF pulse is turned on exactly at the center of the nth echo, which returns all the magnetization left at this time to the static field direction. Only one frequency is used for excitation in acquiring the NMR signal in the single slice mode. Gradients are adjusted for oblique scanning. In the multislice acquisition mode, RF phases of different slices are different from one another and the final images can be constructed either by sharing the kg space or by using a transform process to separate the slices.

An NMR imaging process utilizes both driven equilibrium and fast-spin echo techniques to acquire image data. The fast-spin echo technique is a multi-echo imaging sequence, where a 90-degree RF pulse applied at the center of any echo turns the magnetization back in the direction of the static magnetic field. Within a short waiting time after that pulse, the spins are ready to be excited again. The sequence follows a first 90-degree RF pulse by a series of n 180-degree RF pulses, followed by n echoes. A second 90-degree RF pulse applied to the nth echo returns the magnetization. A multiple single-slice mode is utilized to acquire individual slice images one at a time. A continuous single-slice mode is utilized to acquire individual slice images automatically in sequence over the region of interest. In either mode, adjacent slices can be made to overlap to a degree ranging from 0% to 100%.

A method of stabilizing the static magnetic field in a magnetic resonance imaging (MRI) system applies a radio frequency pulse to a test sample within the static magnetic field and an NMR signal is acquired from the test sample. A characteristic of a signal indicative of the NMR signal, such as the area, phase or the sum of the differences of sampled values is ascertained. In addition, the number of recurring features, such as zero-crossings, of the signal indicative of the NMR signal can be determined and a correction signal is generated to adjust the static magnetic field via a set of correction coils driven by a signal derived from the number of recurring features and the value of the characteristic. Apparatus for stabilizing the static magnetic field is also disclosed.

Method and apparatus for magnetic field stabilization in a MRI system

Methods and apparatus for kinematic studies of the movable joints of the body using magnetic resonance imaging. The apparatus controls the position of movable joints at a multiplicity of predetermined positions, enabling the controlled movement of the joints to each of the predetermined positions. It also includes a device which automatically sequences the movement of a movable joint to each position among the multiplicity of predetermined positions, and the acquisition of magnetic resonance imaging data at each of these positions. These features enhance the clinical utility of kinematic studies of movable joint functionality by magnetic resonance imaging.

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Dix Hills, NY, United States of America

Rajendra K Shenoy