Abstract: A method for correcting one or more artifacts within a multi-spectral magnetic resonance image is provided. The method includes acquiring a plurality of spectral bins each including a plurality of voxels and corresponding to a different frequency of MR signals emitted by an imaged object. The plurality of voxels of each spectral bin correspond to the frequency of the spectral bin so as to define a spatial coverage of the spectral bin. The method further includes expanding each spectral bin by increasing the spatial coverage of the spectral bin, and generating the multi-spectral magnetic resonance image based at least in part on the expanded spectral bins.

Abstract: A method includes: accessing MRI data acquired from a joint area, the MRI data including a series of spatially mapped spectral data points; generating MRI images of the joint area; receiving information encoding a region of interest that encompasses a suspected metal particle deposition area over at least one of the MRI images; constructing magnetic field maps using the MRI data, each representing off-resonance frequency shifts over the joint area; removing a background of off-resonance field inhomogeneity from the magnetic field map such that the region of interest is free from off-resonance field inhomogeneity; identifying clusters from the magnetic field maps with the background of off-resonance field inhomogeneity removed, the clusters defined over a first dimension of offset frequencies and a second dimension of cluster volumes; and computing a quantitative metric by combining information from the identified clusters according to both the first dimension and the second dimension.

Abstract: A magnetic resonance imaging (MRI) system can include a magnetic resonance imaging (MRI) scanner, having a plurality of radio frequency (RF) receivers, and a processor. The MRI scanner can perform a full field of view (fFOV) scan on an anatomy area including an implant to acquire first multi-spectral MRI data associated with a plurality of frequency bins. The processor can generate, for each pair of a single RF receiver and a single frequency bin, a respective spectral sensitivity map using at least a portion of the fFOV multi-spectral MRI data. The MRI scanner can perform a reduced FOV (rFOV) scan to acquire second multi-spectral MRI data associated with the plurality of frequency bins. The processor can reconstruct one or more MRI images according to the rFOV using the rFOV multi-spectral MRI data and the spectral sensitivity maps.

Abstract: An imaging system and method are disclosed. An MR image and measured B0 field map of a target volume in a subject are reconstructed, where the MR image includes one or more bright and/or dark regions. One or more distinctive constituent materials corresponding to the bright regions are identified. Each dark region is iteratively labeled as one or more ambiguous constituent materials. Susceptibility values corresponding to each distinctive and iteratively labeled ambiguous constituent material is assigned. A simulated B0 field map is iteratively generated based on the assigned susceptibility values. A similarity metric is determined between the measured and simulated B0 field maps. Constituent materials are identified in the dark regions based on the similarity metric to ascertain corresponding susceptibility values. The MRI data is corrected based on the assigned and ascertained susceptibility values. A diagnostic assessment of the target volume is determined based on the corrected MRI data.

Abstract: A magnetic resonance imaging (MRI) system can include a magnetic resonance imaging (MRI) scanner, having a plurality of radio frequency (RF) receivers, and a processor. The MRI scanner can perform a full field of view (fFOV) scan on an anatomy area including an implant to acquire first multi-spectral MRI data associated with a plurality of frequency bins. The processor can generate, for each pair of a single RF receiver and a single frequency bin, a respective spectral sensitivity map using at least a portion of the fFOV multi-spectral MRI data. The MRI scanner can perform a reduced FOV (rFOV) scan to acquire second multi-spectral MRI data associated with the plurality of frequency bins. The processor can reconstruct one or more MRI images according to the rFOV using the rFOV multi-spectral MRI data and the spectral sensitivity maps.

Abstract: A method for correcting one or more artifacts within a multi-spectral magnetic resonance image is provided. The method includes acquiring a plurality of spectral bins each including a plurality of voxels and corresponding to a different frequency of MR signals emitted by an imaged object. The plurality of voxels of each spectral bin correspond to the frequency of the spectral bin so as to define a spatial coverage of the spectral bin. The method further includes expanding each spectral bin by increasing the spatial coverage of the spectral bin, and generating the multi-spectral magnetic resonance image based at least in part on the expanded spectral bins.

Abstract: A method for attenuation correcting a PET image of a target includes locating a radiopaque structure by MRI scan of the target; fitting a model of the radiopaque structure to the MRI scan image; and correcting attenuation of the PET image based on the fitted model.

Abstract: A method for acquiring 3D multispectral MRI of a target includes scanning a spectrum of spectral windows with an MRI scanner, wherein each spectral window of the spectrum defines a continuously-differentiable distribution of frequencies around a scan frequency and adjacent scan frequencies are spaced apart by substantially uniform frequency offsets such that adjacent spectral windows substantially uniformly overlap, wherein selected adjacent spectral windows are scanned in consecutive passes, and nearest neighbor spectral windows within each pass are scanned at a maximum temporal spacing within the pass.

Abstract: An imaging system and method are disclosed. An MR image and measured B0 field map of a target volume in a subject are reconstructed, where the MR image includes one or more bright and/or dark regions. One or more distinctive constituent materials corresponding to the bright regions are identified. Each dark region is iteratively labeled as one or more ambiguous constituent materials. Susceptibility values corresponding to each distinctive and iteratively labeled ambiguous constituent material is assigned. A simulated B0 field map is iteratively generated based on the assigned susceptibility values. A similarity metric is determined between the measured and simulated B0 field maps. Constituent materials are identified in the dark regions based on the similarity metric to ascertain corresponding susceptibility values. The MRI data is corrected based on the assigned and ascertained susceptibility values. A diagnostic assessment of the target volume is determined based on the corrected MRI data.

Abstract: A method includes: accessing MRI data acquired from a joint area, the MRI data including a series of spatially mapped spectral data points; generating MRI images of the joint area; receiving information encoding a region of interest that encompasses a suspected metal particle deposition area over at least one of the MRI images; constructing magnetic field maps using the MRI data, each representing off-resonance frequency shifts over the joint area; removing a background of off-resonance field inhomogeneity from the magnetic field map such that the region of interest is free from off-resonance field inhomogeneity; identifying clusters from the magnetic field maps with the background of off-resonance field inhomogeneity removed, the clusters defined over a first dimension of offset frequencies and a second dimension of cluster volumes; and computing a quantitative metric by combining information from the identified clusters according to both the first dimension and the second dimension.

Abstract: An apparatus for detecting and repairing a ring artifact in a multi-spectral magnetic resonance image includes an image processor, which is configured to obtain an off-resonance magnetic field map and a deblurred composite image, to calculate a spatial gradient of the image based on the magnetic field map, to kernel search the spatial gradient, to mask the image, based on the kernel search, in order to identify voxels affected by a ring artifact, and to apply a filter in order to smooth intensities of the voxels identified by the image mask.

Abstract: An apparatus for detecting and repairing a ring artifact in a multi-spectral magnetic resonance image includes an image processor, which is configured to obtain an off-resonance magnetic field map and a deblurred composite image, to calculate a spatial gradient of the image based on the magnetic field map, to kernel search the spatial gradient, to mask the image, based on the kernel search, in order to identify voxels affected by a ring artifact, and to apply a filter in order to smooth intensities of the voxels identified by the image mask.

Abstract: A method includes receiving a forward spatial encoding polarity magnetic resonance (MR) coil image and a reverse spatial encoding polarity MR coil image generated from data obtained with a magnetic field gradient that is reversed with respect to the magnetic field gradient with which the forward spatial encoding polarity MR coil image is acquired. The method also includes performing an iterative shift map calculation algorithm to determine a pixel shift map corresponding to a minimized difference between the forward and reverse spatial encoding polarity MR coil images, converting the pixel shift map into a magnetic field shift map by determining a magnetic field value corresponding to each pixel in the pixel shift map, and providing the magnetic field shift map as an input to a shim calculation process that includes determining a level of at least one shim current.

Abstract: A method for attenuation correcting a PET image of a target includes locating a radiopaque structure by MRI scan of the target; fitting a model of the radiopaque structure to the MRI scan image; and correcting attenuation of the PET image based on the fitted model.

Abstract: A method for acquiring 3D multispectral MRI of a target includes scanning a spectrum of spectral windows with an MRI scanner, wherein each spectral window of the spectrum defines a continuously-differentiable distribution of frequencies around a scan frequency and adjacent scan frequencies are spaced apart by substantially uniform frequency offsets such that adjacent spectral windows substantially uniformly overlap, wherein selected adjacent spectral windows are scanned in consecutive passes, and nearest neighbor spectral windows within each pass are scanned at a maximum temporal spacing within the pass

Abstract: A method includes receiving a forward spatial encoding polarity magnetic resonance (MR) coil image and a reverse spatial encoding polarity MR coil image generated from data obtained with a magnetic field gradient that is reversed with respect to the magnetic field gradient with which the forward spatial encoding polarity MR coil image is acquired. The method also includes performing an iterative shift map calculation algorithm to determine a pixel shift map corresponding to a minimized difference between the forward and reverse spatial encoding polarity MR coil images, converting the pixel shift map into a magnetic field shift map by determining a magnetic field value corresponding to each pixel in the pixel shift map, and providing the magnetic field shift map as an input to a shim calculation process that includes determining a level of at least one shim current.