Massachusetts Institute of Technology

The General Hospital Corporation

National Institutes of Health, a Component of the US Dept. of Health & Human Services

Siemens Healthcare Gmbh

Siemens Aktiengesellschaft

Vivek K Goyal

Lawrence Leroy Wald

Leo John Grady

Elfar Adalsteinsson

Daniel Weller

Adam C Zelinski

Ghulam Ahmed Kirmani

Kawin Setsompop

Jonathan R Polimeni

Muriel Médard

Soheil Feizi-Khankandi

Vijay Alagappan

Diffuse image measurement system and digital image formation method. The system includes a source of light with time-varying intensity directed at a scene to be imaged. A time-resolved light meter is provided for receiving light reflected from the scene to generate time-resolved samples of the intensity of light incident at the light meter. The temporal variation in the intensity of light incident at the light meter is associated with a function of a radiometric property of the scene, such as a linear functional of reflectance, and a computer processes the samples to construct a digital image. The spatial resolution of the digital image is finer than the spatial support of the illumination on the scene and finer than the spatial support of the sensitivity of the light meter. Using appropriate light sources instead of impulsive illumination significantly improves signal-to-noise ratio and reconstruction quality.

System and method for diffuse imaging with time-varying illumination intensity

An MR imaging system uses multiple RF coils for acquiring corresponding multiple image data sets of a slice or volume of patient anatomy. An image data processor comprises at least one processing device conditioned for, deriving a first set of weights for weighted combination of k-space data of the multiple image data sets for generating a calibration data set comprising a subset of k-space data of composite image data representing the multiple image data sets. The image data processor uses the calibration data set in generating a first MR image data set, deriving the parameters of a probability distribution in response to the first set of weights and the first MR image data set and deriving a second set of weights and second MR image data set together using the probability distribution.

System for accelerated magnetic resonance imaging using parallel coils

A system for parallel image processing in MR imaging comprises multiple MR imaging RF coils for individually receiving MR imaging data representing a slice of patient anatomy. An MR imaging system uses the multiple RF coils for acquiring corresponding multiple image data sets of the slice. An image data processor comprises at least one processing device conditioned for, deriving a first set of weights for generating a calibration data set comprising a subset of k-space data of composite image data representing the multiple image data sets. The at least one processing device uses the calibration data set in generating a first MR image data set, deriving a second set of weights using the calibration data set and the generated first MR image data set and uses the second set of weights in generating a second MR image data set representing a single image having a reduced set of data components relative to the first composite MR image data set.

System for reconstructing MRI images acquired in parallel

Described herein is a sampling system and related sampling scheme. The system and sampling scheme is based upon a framework for adaptive non-uniform sampling schemes. In the system and schemes described herein, time intervals between samples can be computed by using a function of previously taken samples. Therefore, keeping sampling times (time-stamps), except initialization times, is not necessary. One aim of this sampling framework is to provide a balance between reconstruction distortion and average sampling rate. The function by which sampling time intervals can be computed is called the sampling function. The sampling scheme described herein can be applied appropriately on different signal models such as deterministic or stochastic, and continuous or discrete signals. For each different signal model, sampling functions can be derived.

Energy-efficient time-stampless adaptive nonuniform sampling

Depth information about a scene of interest is acquired by illuminating the scene, capturing reflected light energy from the scene with one or more photodetectors, and processing resulting signals, in at least one embodiment, a pseudo-randomly generated series of spatial light modulation patterns is used to modulate the light pulses either before or after reflection.

Method and apparatus to determine depth information for a scene of interest

An MR imaging system uses the multiple RF coils for acquiring corresponding multiple image data sets of the slice. An image data processor comprises at least one processing device conditioned for, generating a composite MR image data set representing a single image in a single non-iterative operation by performing a weighted combination of luminance representative data of individual corresponding pixels of the multiple image data sets in providing an individual pixel luminance value of the composite MR image data set. The image data processor reduces noise in the composite MR image data set by generating a reduced set of significant components in a predetermined transform domain representation of data representing the composite image to provide a de-noised composite MR image data set. An image generator comprises at least one processing device conditioned for, generating a composite MR image using the de-noised composite MR image data set.

System for accelerated MR image reconstruction

A system and method is provided for simultaneously designing a radiofrequency ('RF') pulse waveform and a magnetic field gradient waveform in a magnetic resonance imaging ('MRI') system. The method includes determining a desired pattern of RF excitation and determining, from the desired pattern of RF excitation, a plurality of k-space locations indicative of the magnetic field gradient waveform and a plurality of complex weighting factors indicative of RF energy deposited at each k-space location. The method also includes calculating, from the determined k-space locations, the magnetic field gradient waveform and calculating, from the complex weighting factors, the RF pulse waveform that will produce the desired pattern of RF excitation when produced with the calculated magnetic field gradient.

Method for joint sparsity-enforced k-space trajectory and radiofrequency pulse design

A method for reducing maximum local specific absorption rate ('SAR') in a magnetic resonance imaging ('MRI') system is disclosed. More specifically, a plurality of candidate radio frequency (&#x201c;RF&#x201d;) pulses are designed and the manner in which they are applied to a subject is determined such that the maximum local SAR is substantially reduced relative to applying the candidate RF pulse that produces the lowest maximum local SAR alone. Put another way, this &#x201c;time-multiplexing&#x201d; of a set of RF pulses that each produce approximately the same excitation pattern yields a lower maximum local SAR than does transmitting the individual RF pulse having the lowest local SAR over many repetition times (&#x201c;TRs&#x201d;). A convex optimization method is utilized to determine the manner in which the RF pulses are multiplexed in time such that a substantially lower maximum local SAR is achieved.

Method for reducing maximum local specific absorption rate in magnetic resonance imaging

A method for target-dependent, sparsity-enforced selection for choosing a substantially optimal connection of radiofrequency ('RF') transmitters to the elements of the RF coil array is provided. In particular, a method is provided that selects the linear combinations of the 'N' spatial mode profiles of a transmission RF coil array, such that the k-space trajectory and pulse duration acceleration capabilities of the array are advantageously utilized. A sparsity-enforcement method that determines a subset of the available spatial modes for a parallel transmission RF coil array is employed to this end. In this manner, the utilization of the encoding power of a highly-parallel N-mode coil array in a system with only &#x201c;P&#x201d; available excitation channels is enabled.

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Cambridge, MA, United States of America

Vivek K Goyal