摘要:
A remotely controlled magnetic resonance guided focused ultrasound system includes a magnetic resonance scanner and focused ultrasound transducer assembly at a location where a patient is to be treated, and a control station which is not immediately at the location where the patient is to be treated. The control station may be remote from the patient location, and connected to the scanner and the transducer assembly via a network. A local controller aids in acquiring magnetic resonance guide images and thermographic images during sonication. The sonication itself is controlled remotely by a surgeon by the control station.
摘要:
A pair of serially-connected coils detect noise variations in an MRI background magnetic field. Although the coils are closely coupled to the primary background magnetic field generator of the MRI system, they are disposed so as to be substantially de-coupled from rapidly changing MRI gradient magnetic fields. The noise detecting loops drive a negative feedback loop including a low pass filter, amplifier and controlled current source driving a large correcting loop. The device attenuates background magnetic field noise during MRI data acquisition over a frequency band extending from a few millihertz to more than 100 Hz. It is preferably used with existing field stabilization software that otherwise compensates for fluctuations in an overlapping frequency band which starts at d.c. Thus, when used together, background magnetic field noise may be attenuated (or compensated for in subsequent MRI data processing) over a frequency band that extends from d.c. to more than 100 Hz.
摘要:
Methods and apparatus for correcting image artefacts caused by variations in the main magnetic field of an MRI system are disclosed, particularly for MRI with steady-state spin precession. For field correction in MRI with steady-state spin precession, the effects of the field changes can be corrected by quantifying the time course of the field drifts by repeated acquisition of the zero k-space lines. The change in the phase between consecutive zero k-space lines is used as an indicator of field variation and for correction of associated image artifacts. By using for field correction the zero k-space lines acquired using the imaging sequence itself, the steady-states of spin precession are undisturbed throughout the MRI data acquisition.
摘要:
A method for attenuation correction of a plurality of time-gated PET images of a moving structure includes establishing an ACF matrix, based on a baseline MR image of the structure; developing a plurality of image transforms, each of the image transforms registering the baseline MR image to a respective cine MR image of the moving structure; applying each of the image transforms to the ACF matrix to generate a corresponding cine ACF matrix; time-correlating each of the cine MR images, and its corresponding cine ACF matrix, to one of the plurality of time-gated PET data sets; and producing from each of the time-gated PET data sets an attenuation-corrected time-gated PET image.
摘要:
A method for attenuation correction of a plurality of time-gated PET images of a moving structure includes establishing an ACF matrix, based on a baseline MR image of the structure; developing a plurality of image transforms, each of the image transforms registering the baseline MR image to a respective cine MR image of the moving structure; applying each of the image transforms to the ACF matrix to generate a corresponding cine ACF matrix; time-correlating each of the cine MR images, and its corresponding cine ACF matrix, to one of the plurality of time-gated PET data sets; and producing from each of the time-gated PET data sets an attenuation-corrected time-gated PET image.
摘要:
A system for isolating vibration and reducing acoustic noise in the RF coil of an MR imaging apparatus is presented. The system positions an RF conductor in its operative position proximate to an RF support form. The RF conductor is sandwiched between a vibration decoupling layer and a mass loading layer. The vibration decoupling layer is affixed to the RF support form so that the vibration decoupling layer is positioned between the RF conduit and the RF support form while the mass loading layer is located exterior of the RF conductor. By this arrangement, the acoustic energy is decoupled from the RF support form by the vibration decoupling layer while the vibration is reduced by the mass loading layer located exterior of the RF conductor.
摘要:
A system for isolating vibration and reducing acoustic noise in the RF coil of an MR imaging apparatus is presented. The system positions an RF conductor in its operative position proximate to an RF support form. The RF conductor is sandwiched between a vibration decoupling layer and a mass loading layer. The vibration decoupling layer is affixed to the RF support form so that the vibration decoupling layer is positioned between the RF conduit and the RF support form while the mass loading layer is located exterior of the RF conductor. By this arrangement, the acoustic energy is decoupled from the RF support form by the vibration decoupling layer while the vibration is reduced by the mass loading layer located exterior of the RF conductor.
摘要:
A method and apparatus for obtaining three MRI image data in a single data acquisition TR interval for use in constructing separate water and fat images by appropriate processing of the three images data is disclosed. The three image data are obtained in one exemplary embodiment by sandwiching a spin echo between two field echoes. The invention can also be used for multiple-echo and multiple-slice 3D scans.