Leland Stanford Junior University

University of California

Other

University of Florida Research Foundation Inc

Steven M Conolly

Patrick W Goodwill

John Mark Pauly

Daniel Hensley

Bo Zheng

Hao Xu

Charles H Cunningham

Zhi Wei Tay

Norbert Joseph Pelc

Brian A Hargreaves

Dwight G Nishimura

Rebecca Fahrig

Bob S Hu

Patrick N Morgan

Albert Macovski

Lei Xing

Greig Scott

Paul J Keall

Amit Ramakant Sawant

Carlos Rinaldi

Kim Butts Pauly

Sanjay Mani

Peder E Larson

Prashant Chandrasekharan

Rohan Deepak Dhavalikar

Shehaab Savliwala

A pulsed magnetic particle imaging system includes a magnetic field generating system that includes at least one magnet, the magnetic field generating system providing a spatially structured magnetic field within an observation region of the magnetic particle imaging system such that the spatially structured magnetic field will have a field-free region (FFR) for an object under observation having a magnetic nanoparticle tracer distribution therein. The pulsed magnetic particle imaging system also includes a pulsed excitation system arranged proximate the observation region, the pulsed excitation system includes an electromagnet and a pulse sequence generator electrically connected to the electromagnet to provide an excitation waveform to the electromagnet, wherein the electromagnet when provided with the excitation waveform generates an excitation magnetic field within the observation region to induce an excitation signal therefrom by at least one of shifting a location or condition of the FFR. The pulsed magnetic particle imaging system further includes a detection system arranged proximate the observation region, the detection system being configured to detect the excitation signal to provide a detection signal. The excitation waveform includes a transient portion and a substantially constant portion.

Pulsed magnetic particle imaging systems and methods

A magnetic particle imaging system that includes a magnetic field generating system with at least one magnet and providing a gradient magnetic field within an observation region such that the gradient magnetic field has a dynamic field-free region (FFR) for an object under observation having strongly-interacting magnetic particles distributed therein. The magnetic field generating system also includes a drive field and a slow shift field that dynamically shifts the FFR across a field of view (FOV) within the observation region, where the trajectory of the drive field accommodates for a coercivity of the strongly-interacting magnetic particles by ensuring that the particles in the FOV are saturated to a full coercivity field prior to traversing to an opposite-polarity of coercivity. The magnetic particle imaging system also includes a detection system proximate the observation region and configured to detect a signal from the strongly-interacting magnetic particles. The magnetic particle imaging system further includes signal processor in communication with the detection system, configured to receive and process the detected signal to remove a coercivity shift due to the coercivity of the strongly-interacting magnetic particles, and convert the processed detection signal into an image of the strongly-interacting magnetic particles.

Strongly-interacting magnetic particle imaging

A magnetic particle imaging apparatus includes magnets [] that produce a gradient magnetic field having a field free region (FFR), excitation field electromagnets [] that produce a radiofrequency magnetic field within the field free region, high-Q receiving coils [] that detect a response of magnetic particles in the field free region to the excitation field. Field translation electromagnets create a homogeneous magnetic field displacing the field-free region through the field of view (FOV) allowing the imaging region to be scamled to optimize scan time, scanning power, amplifier heating, SAR, dB/dt, and/or slew rate. Efficient multi-resolution scanning techniques are also provided. Intermodulated low and radio-frequency excitation signals are processed to produce an image of a distribution of the magnetic nanoparticles within the imaging region. A single composite image is computed using deconvolution of multiple signals at different harmonics.

Techniques for magnetic particle imaging

A magnetic particle imaging device is provided. The device includes a magnetic field source configured to produce a magnetic field having a non-saturating magnetic field region, an excitation signal source configured to produce an excitation signal in the non-saturating magnetic field region that produces a detectable signal from magnetic particles in the non-saturating magnetic field region, and a signal processor configured to convert a detected signal into an image of the magnetic particles. Aspects of the present disclosure also include methods of imaging magnetic particles in a sample, and methods of producing an image of magnetic particles in a subject. The subject devices and methods find use in a variety of applications, such as medical imaging applications.

Magnetic particle imaging devices and methods

A magnetic particle imaging apparatus includes magnets [] that produce a gradient magnetic field having a field free region (FFR), excitation field electromagnets [] that produce a radiofrequency magnetic field within the field free region, high-Q receiving coils [] that detect a response of magnetic particles in the field free region to the excitation field. Field translation electromagnets create a homogeneous magnetic field displacing the field-free region through the field of view (FOV) allowing the imaging region to be scaled to optimize scan time, scanning power, amplifier heating, SAR, dB/dt, and/or slew rate. Efficient multi-resolution scanning techniques are also provided. Intermodulated low and radio-frequency excitation signals are processed to produce an image of a distribution of the magnetic nanoparticles within the imaging region. A single composite image is computed using deconvolution of multiple signals at different harmonics.

A magnetic particle imaging apparatus includes magnets [] that produce a gradient magnetic field having a field free region (FFR), excitation field electromagnets [] that produce a radiofrequency magnetic field within the field free region, high-Q receiving coils [] that detect a response of magnetic particles in the field free region to the excitation field. Field translation electromagnets create a homogeneous magnetic field displacing the field-free region through the field of view (FOV) allowing the imaging region to be scanned to optimize scan time, scanning power, amplifier heating, SAR, dB/dt, and/or slew rate. Efficient multi-resolution scanning techniques are also provided. Intermodulated low and radio-frequency excitation signals are processed to produce an image of a distribution of the magnetic nanoparticles within the imaging region. A single composite image is computed using deconvolution of multiple signals at different harmonics.

The present invention provides a radiotherapy treatment apparatus that includes a treatment beam, a magnetic field disposed parallel collinear to the treatment beam, and a target that is disposed along the treatment beam. The treatment beam can be a charged particle beam, a proton beam, an electron beam, or a linear accelerator (Linac) beam. The magnetic field is from a magnetic resonance imager (MRI), a megavolt x-ray imager, or a kilovolt x-ray imager and is disposed to operate in coordination with operation of the treatment beam and to narrow the beam. The tumor is disposed to rotate with respect to the treatment beam and the magnetic field, or the treatment beam and the magnetic field are disposed to rotate up to 360&#xb0; with respect to the target when mounted to a ring gantry. The apparatus can include a rotation angle dependent shim disposed to account for Earth's magnetic field.

Configurations for integrated MRI-linear accelerators

Off-resonance imaging uses two complementary contrast agents with the first agent (iron-oxide) particles transfected into cells which provide localized signals. The second agent is detected from a change in the off-resonance signal when present in the cells labeled by the first agent.

Method of off-resonance detection using complementary MR contrast agents

Contrast agents incorporating super-paramagnetic iron-oxide (SPIO) nanoparticles have shown promise as a means to visualize labeled cells using MRI. Labeled cells cause significant signal dephasing due to the magnetic field inhomogeneity induced in water molecules near the cell. With the resulting signal void as the means for detection, the particles are behaving as a negative contrast agent, which can suffer from partial-volume effects. Disclosed is a new method for imaging labeled cells with positive contrast. Spectrally-selective RF pulses are used to excite and refocus the off-resonance water surrounding the labeled cells so that only the fluid and tissue immediately adjacent to the labeled cells are visible in the image. Phantom, in vitro, and in vivo experiments show the feasibility of the new method. A significant linear correlation (r=0.87, p&#x3c;0.005) between the estimated number of cells and the signal has been observed.

Positive contrast MRI of magnetically tagged cells, objects, tissues

A time-optimal MRI gradient design method utilizes constrained optimization to design minimum-time gradient waveforms that satisfy gradient amplitude and slew-rate limitations. Constraints are expressed as linear equations which are solved using linear programming, L1-norm formulation, or second-order cone programming (SOCP).

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Palo Alto, CA, United States of America

Steven M Conolly