Abstract: In one aspect, in accordance with one embodiment, a method includes acquiring magnetic resonance (MR) data corresponding to bone tissue in an area of interest of a subject that is heated from the application of localized energy. The acquiring includes applying a three-dimensional (3D) ultra-short echo time (UTE) spiral acquisition sequence. The method also includes detecting, from the acquired magnetic resonance data, a change in MR response signal due to a change in at least one of relaxation rate and magnetization density caused by heating of the bone tissue; and determining, based at least in part on the change in the MR response signal, that the temperature of the bone tissue has changed.

Abstract: Aspects of the present disclosure relate to magnetic resonance thermometry. In one embodiment, a method includes acquiring undersampled magnetic resonance data associated with an area of interest of a subject receiving focused ultrasound treatment, and reconstructing images corresponding to the area of interest based on the acquired magnetic resonance data, where the reconstructing uses Kalman filtering.

Abstract: In one aspect, in accordance with one embodiment, a method includes acquiring magnetic resonance (MR) data corresponding to bone tissue in an area of interest of a subject that is heated from the application of localized energy. The acquiring includes applying a three-dimensional (3D) ultra-short echo time (UTE) spiral acquisition sequence. The method also includes detecting, from the acquired magnetic resonance data, a change in MR response signal due to a change in at least one of relaxation rate and magnetization density caused by heating of the bone tissue; and determining, based at least in part on the change in the MR response signal, that the temperature of the bone tissue has changed.

Abstract: Aspects of the present disclosure relate to magnetic resonance thermometry. In one embodiment, a method includes acquiring undersampled magnetic resonance data associated with an area of interest of a subject receiving focused ultrasound treatment, and reconstructing images corresponding to the area of interest based on the acquired magnetic resonance data, where the reconstructing uses Kalman filtering.

Abstract: Proton resonance frequency shift thermometry may be improved by combining multibaseline and referenceless thermometry.

Abstract: The phase background of a proton resonance frequency shift treatment image may be estimated by fitting a combination of baseline images to the treatment image.

Abstract: Proton resonance frequency shift thermometry may be improved by combining multibaseline and referenceless thermometry.

Abstract: The phase background of a proton resonance frequency shift treatment image may be estimated by fitting a combination of baseline images to the treatment image.

Abstract: Improved compatibility of MRI with radiation imaging is provided by MRI RF coils having transmissive coil sections. The transmissive coil sections are substantially transparent to the penetrating radiation employed by the radiation imaging system. Thus the transmissive coil sections can be disposed in a field of view of the radiation imaging system without introducing artifacts into the radiation images. Transparency to penetrating radiation can be achieved by substantially including only low atomic number (i.e., Z<29) elements in the transmissive coil sections. Preferably, the transmissive coil sections are fabricated substantially from aluminum.

Abstract: Magnetic resonance imaging utilizes view angle tilting to correct for in-plane distortions with each RF excitation pulse being followed by a plurality of signal readouts to reduce image blurring. Each image readout is in the presence of a frequency select gradient (GX) and a slice select gradient (GZ), and at least the slice select gradient is refocused after each readout of an image signal. Each readout can have a time duration of the main lobe of the RF excitation pulse or the readout can have a higher bandwidth with an increased number of readouts. The combining of multiple readouts diminishes slice profile modulation resulting from Fourier transform.

Abstract: Magnetic resonance imaging utilizes view angle tilting to correct for in-plane distortions with each RF excitation pulse being followed by a plurality of signal readouts to reduce image blurring. Each image readout is in the presence of a frequency select gradient (Gx) and a slice select gradient (Gz), and at least the slice select gradient is refocused after each readout of an image signal. Each readout can have a time duration of the main lobe of the RF excitation pulse or the readout can have a higher bandwidth with an increased number of readouts. The combining of multiple readouts diminishes slice profile modulation resulting from Fourier transform.

Abstract: The present invention provides a method for view-angle tilt magnetic resonance imaging of an object having a localized variation of magnetic susceptibility. The method includes the steps of: applying an RF excitation pulse and a first field gradient simultaneously to the object; applying an RF refocusing pulse and a second field gradient simultaneously to the object; and applying a tilted readout gradient to the object, where the tilt angle is selected to provide incomplete removal of the image distortion produced by the magnetic susceptibility variation. In this manner, magnetic susceptibility contrast is provided in the region of variable magnetic susceptibility. Adjustment of the tilt angle can be used to provide a desired amount of magnetic susceptibility contrast.

Abstract: The present invention provides methods for adjustment of contrast of magnetic susceptibility variations where the variations cause distortions which are removed by view angle tilting. Often, magnetic susceptibility variations are caused by devices such as needles inserted into a patient. In two methods of the present invention, first and second field gradients are applied simultaneous with excitation and refocusing gradients, respectively. The first and second gradients have different amplitudes or orientations, or both. This results in fewer spins rephasing in the vicinity of the susceptibility variation than elsewhere, thereby providing contrast. In another embodiment of the invention, a spin echo is produced, and the detection time of the spin echo signal is offset from the time of the spin echo. The offset results in a phase cancellation of spins near the susceptibility variation due to the relatively large range of magnetic field strengths. Other methods of the present invention are also disclosed.

Abstract: Temperature in frozen tissue can be measured from magnetic resonance signals from the frozen tissue based on spin-spin relaxation time (T2) or based on relative intensity of the magnetic resonance signals. Short echo times are required, and use of tailored RF pulses, non-Cartesian readouts, and multi-slice and 3D k-space acquisitions are preferably employed.