The General Hospital Corporation

Siemens Healthcare Gmbh

Siemens Aktiengesellschaft

Massachusetts Institute of Technology

Massachusetts General Hospital Corporation

The Government of the United States of America As Represented by the Secretary of the Deptartment of Health and Human Services

Case Western Reserve University

The Mclean Hospital Corporation

University of Southern California

Lawrence Leroy Wald

Kawin Setsompop

Stephen Farman Cauley

Elfar Adalsteinsson

Bastien Guerin

Bruce R Rosen

Berkin Bilgic

Jason Stockmann

Jonathan R Polimeni

Vivek K Goyal

Vijayanand Alagappan

Thomas Witzel

Fuyixue Wang

Mathias Davids

Patrick C McDaniel

Clarissa Zimmerman-Cooley

Leo John Grady

Markus Vester

Mark A Griswold

Hua Guo

Matthew Scot Rosen

Luca Daniel

Melissa Haskell

Daniel Weller

Adam C Zelinski

Timothy G Reese

Clarissa Zimmerman

Zohaib Mahmood

Bo Zhao

Huihui Ye

Zijing Dong

Sai Abitha Srinivas

Cornelius Eichner

Stefan Popescu

Hans-Peter Fautz

Matthias Gebhardt

Peter Dietz

Josef Pfeuffer

Perry F Renshaw

Dan Ma

Andreas Krug

Yun Jiang

Daniel Polak

Axel Vom Endt

Andre Van Der Kouwe

Bo Zhu

Blaise deB Frederick

Bruce Fischl

Justin P Haldar

Borjan Aleksandar Gagoski

Graham Charles Wiggins

Boris Keil

Jason Stockman

Sohyun Han

Joonsung Lee

Vijay Alagappan

Cristen LaPierre

Clarissa Z Cooley

A single-sided magnet and magnetic resonance imaging ('MRI') system are portable and lightweight, enabling use as a point-of care (“POC”) MRI device. The portable MRI system includes a magnet assembly containing layers of magnet blocks, such as rare-earth magnet blocks. The magnet blocks are arranged in concentric rings in each layer, and surround a central aperture extending through the magnet assembly. The central aperture is sized to allow a medical instrument, such as a needle, to pass through the central aperture. The portable MRI system can therefore be used for image guidance in lumbar puncture (“LP”) and other medical procedures.

Point-of-care magnetic resonance imaging system for lumbar puncture guidance

Asymmetric, single-channel radio frequency ('RF') coils are provided for use with portable or other low-field magnetic resonance imaging (“MRI”) systems. In general, the asymmetric, single-channel RF coils make use of asymmetric, optimized winding configurations in order to reduce B1+ inhomogeneities and to reduce signal sensitivity outside of the desired imaging field-of-view (“FOV”).

Asymmetric single-channel radio frequency helmet coil for magnetic resonance imaging

A method for assessing peripheral nerve stimulation (PNS) for a coil geometry includes retrieving a PNS Huygens' P-matrix for a body model. The PNS Huygens' P-matrix is defined on a Huygens' surface enclosing the body model. The method further includes generating a coil specific PNS P-matrix for the coil geometry based on at least the PNS Huygens' P-matrix for the body model, determining at least one PNS threshold for the coil geometry based on the coil specific PNS P-matrix, and storing the at least one PNS threshold in a storage device.

System for and method of rapid peripheral nerve stimulation assessment of gradient coils

Electromagnetic interference ('EMI') is mitigated for portable magnetic resonance imaging (“MRI”) systems using postprocessing interference suppression techniques that make use of EMI detectors external to the MRI system imaging volume to detect EMI signals and remove them from acquired magnetic resonance data. EMI correction models, including static transfer function-based models, dynamic transfer function-based models, correction weight-based models, or parallel imaging kernel-based models can be used to remove the EMI-related artifacts from the magnetic resonance data.

System and method for electromagnetic interference mitigation for portable MRI systems

Systems and methods for designing and manufacturing electromagnetic coils for use with a magnetic resonance imaging ('MRI') system are described. More particularly, described here are methods for designing and manufacturing gradient coils for producing magnetic field gradients with greater peripheral nerve stimulation (“PNS”) thresholds relative to conventional gradient coils. The gradient coil design is constrained using an oracle penalty that is computed to account for a PNS requirement for the coil. In other applications, the oracle penalty can be used to optimize driving patterns for an electromagnetic stimulation system, such that a target PNS requirement is achieved.

Method for designing electromagnetic coils with explicit peripheral nerve stimulation constraint based on an oracle penalty

A combined physics-based and machine learning framework is used for reconstructing images from k-space data, in which motion artifacts are significantly reduced in the reconstructed images. In general, model-based retrospective motion correction techniques are accelerated using fast machine learning ('ML') steps, which may be implemented using a trained neural network such as a convolutional neural network. In this way, the confidence of a classical physics-based reconstruction is obtained with the computational benefits of an ML-based network.

Retrospective motion correction using a combined neural network and model-based image reconstruction of magnetic resonance data

A method for determining peripheral nerve stimulation during MR imaging of a patient in a MR scan unit for a MR pulse sequence is described. In the method, a plurality of model-based candidate stimulations are determined dependent on a unit vector potential of the gradient magnet field generated during MR imaging and dependent on candidate data models for different object parameter values. A model-based candidate data stimulation is selected as a stimulation model for the patient dependent on an individual patient model. A distribution of a vector potential of a gradient magnetic field acting on the patient is determined as a function of a unit gradient current for a determined position of the patient in the MR scanning unit. The nerve stimulation of the patient is determined for the determined position based on the selected candidate stimulation and a gradient current of a gradient pulse of the MR pulse sequence.

Patient-model-based determination of a stimulation of a magnetic resonance imaging

A system and method is provided for assessing Peripheral Nerve Stimulation (PNS). The system receives an imaging pulse sequence to be applied to a region of interest (ROI) of a subject arranged in the imaging system, where the imaging pulse sequence identifies coil parameters related to at least one coil. The system obtains a first model including a plurality of tissue types and corresponding electromagnetic properties in the ROI. The system then obtains a second model indicating location, orientation, and/or physiological properties of one or more nerve tracks in the ROI. The system estimates a plurality of PNS thresholds in the ROI caused by the imaging pulse sequence applied in the imaging system using the first model, the second model, a nerve membrane model, and the coil parameters.

System and method for using concomitant fields to control peripheral nerve stimulation (PNS) in MRI image encoding

A magnet assembly for a portable magnetic resonance imaging (MRI) system includes a former having a plurality of slots and a plurality of magnet blocks configured to create a single-sided permanent magnet. Each of the plurality of magnet blocks are positioned in one of the plurality of slots of the former. The arrangement of the plurality of magnet blocks is configured to optimize homogeneity over a target field of view for brain imaging and to form a cap-shaped configuration to be positioned on a head of a subject.

Single-sided 3D magnet and magnetic resonance imaging (MRI) system

Techniques are disclosed related to increasing prior limits imposed on MR gradient switching speed (dB/dt) without causing significant discomfort or severe pain perception to patients. The technique disclosed herein do so by modifying the pulsing gradient fields that are ordinarily available for MR imaging protocols. Doing so stimulates the peripheral nerves and thus enables a quick, reversible, and complete inhibition of action potential propagation through the stimulated region of tissue, referred to as a nerve conduction block.

Avoidance of peripheral nerve stimulation (PNS) using induced analgesia

Systems and methods are provided for improving MRI data acquisition efficiency while providing more detailed information with high resolution and isotropic resolution without gaps. Improved data acquisition efficiency may be achieved by implementing a machine learning algorithm with a hardware processor and a memory to estimate imperfections in fast imaging sequences, such as a multi-shot echo planar imaging (MS-EPI) sequence. These imperfections, such as patient motion, physiological noise, and phase variations, may be difficult to model or otherwise estimate using standard physics-based reconstructions.

Multi-shot echo planar imaging through machine learning

Described here are systems and methods for producing images of a subject using magnetic resonance imaging ('MRI') in which data are acquired using a sparse approximate encoding scheme for controlled aliasing techniques. As one example, the sparse approximate encoding can be used for a Wave-CAIPI encoding scheme, which can enable faster image reconstruction using fewer computational resources, in addition to reducing noise in the reconstructed images relative to those reconstructed from data acquired using a Wave-CAIPI encoding scheme without sparse approximate encoding.

Sparse approximate encoding of Wave-CAIPI: preconditioner and noise reduction

Systems and methods for magnetic resonance imaging ('MRI') that address the geometric distortions and blurring common to conventional echo planar imaging ('EPI') sequences, and that provide new temporal signal evolution information across the EPI readout, are described. Echo planar time-resolved imaging (&#x201c;EPTI&#x201d;) schemes are described to implement an accelerated sampling of a hybrid space spanned by the phase encoding dimension and the temporal dimension. In general, each EPTI shot covers a segment of this hybrid space using a zigzag trajectory with an interleaved acceleration in the phase-encoding direction. The hybrid space may be undersampled and a tilted reconstruction kernel used to synthesize additional data samples.

Method for echo planar time-resolved magnetic resonance imaging

Methods for reducing scan time in magnetic resonance imaging ('MRI'), particularly when imaging three-dimensional image volumes, using a simultaneous time-interleaved multislice ('STIMS') acquisition are described. The unused time in each repetition time (&#x201c;TR&#x201d;) period is exploited to provide an additional reduction in encoding time for a three-dimensional acquisition (e.g., a 3D whole brain coverage). Groups of spatially interleaved slices are excited in a single TR, with the excitation and acquisition of the groups of slices being interleaved in time.

Method for simultaneous time-interleaved multislice magnetic resonance imaging

Described here are systems and methods for retrospectively estimating and correcting for rigid-body motion by using a joint optimization technique to jointly solve for motion parameters and the underlying image. This method is implemented for magnetic resonance imaging ('MRI'), but can also be adapted for other imaging modalities.

Systems and methods for joint image reconstruction and motion estimation in magnetic resonance imaging

Growing community of inventors

Cambridge, MA, United States of America

Lawrence Leroy Wald