Abstract: The invention relates to an apparatus for generating an attenuation correction map. An image providing unit (5, 6) provides an image of an object comprising different element classes and a segmentation unit (11) applies a segmentation to the image for generating a segmented image comprising image regions corresponding to the element classes. The segmentation is based on at least one of a watershed segmentation and a body contour segmentation based on a contiguous skin and fat layers in the image. A feature determination unit (12) determines features of at least one of a) the image regions and b) boundaries between the image regions depending on image values of the image and an assigning unit (13) assigns attenuation values to the image regions based on the determined features for generating the attenuation correction map.

Abstract: When generating a magnetic resonance (MR) attenuation map (39), an MR image is segmented to identify a patient's body outline, soft tissue structures, and ambiguous structures comprising bone and/or air. To distinguish between bone and air in the ambiguous structures, a nuclear emission image (e.g., PET) of the same patient or region of interest is segmented. The segmented functional image data is correlated to the segmented MR image data to distinguish between bone and air in the ambiguous structures. Appropriate radiation attenuation values are assigned respectively to identify air voxels and bone voxels in the segmented MR image, and an MR attenuation map is generated from the enhanced segmented MR image, in which ambiguity between air and bone has been resolved. The MR attenuation map is used to generate an attenuation-corrected nuclear image, which is displayed to a user.

Abstract: A system (10) and method generate one or more MR data sets of an imaging volume (16) using an MR scanner (14). The imaging volume (16) includes one or more of a region of interest (ROI), the ROI including a metal element, and a local receive coil (18) of the MR scanner (14). At least one of an attenuation, confidence or density map accounting for the metal element is generated and the location of the local receive coil (18) within the imaging volume (16) is determined. The generating includes identification of the metal element within the ROI based on a phase map of the ROI generated from the MR data sets. The determining includes registering a known sensitivity profile of the local receive coil (18) to a sensitivity map of the local receive coil (18) generated from the MR data sets.

Abstract: A nuclear imaging system includes a crystal identification system which receives a flood image which includes a plurality of peaks, each peak responsive to radiation detected by a corresponding scintillator crystal. A crystal identification processor partitions the flood image into a plurality of candidate regions with a watershed segmentator implementing a watershed algorithm. The candidate regions are linked in an adjacency graph, and then classified as background or relevant, where relevant regions contain a peak within the watershed lines. The regions are then assigned to a crystal according to an objective function and an assignability score. A calibration processor maps the peaks to a rectangular grid.

Abstract: The invention relates to an apparatus for generating an attenuation correction map. An image providing unit (5, 6) provides an image of an object comprising different element classes and a segmentation unit (11) applies a segmentation to the image for generating a segmented image comprising image regions corresponding to the element classes. The segmentation is based on at least one of a watershed segmentation and a body contour segmentation based on a contiguous skin and fat layers in the image. A feature determination unit (12) determines features of at least one of a) the image regions and b) boundaries between the image regions depending on image values of the image and an assigning unit (13) assigns attenuation values to the image regions based on the determined features for generating the attenuation correction map.

Abstract: Nuclear image data generated by a multimodal imaging device, such as a combined position emission tomography (PET)/magnetic resonance (MR) scanner (12, 14), is attenuation-corrected with a combined patient-specific attenuation correction (AC) map and an AC map template (70) for an MR coil (72) that is present in both the nuclear and MR scanning procedures. A template library (46) contains templates for each of a plurality of MR coils and other accessories. Each template is generated on one of two manners. The coil may be imaged inside the PET scanner 14 with the transmission source 16 (e.g., Ge-68 or Cs-137). A transmission image 48 is reconstructed using the known algorithms and may be used as the AC template directly. Alternatively, the template can be generated by creating a global histogram of the transmission image and identifying segments of the coil or other accessory. An average linear attenuation coefficient (LAC) value is determined from the distribution of the histogram.

Abstract: The invention relates to an apparatus for generating assignments between image regions of an image of an object and element classes. The apparatus (1) comprises an assigning unit (13) for assigning element classes to image regions of an element image of the object, which is indicative of a distribution of the element classes, depending on region and/or boundary features, which are determined depending on image values of a provided object image and provided first preliminary assignments. Thus, the resulting element image with the assignments to the element classes is not necessarily based on the provided object image only, but can also be based on the provided preliminary assignments. If the quality of the assignments defined by the element image would be restricted due to restrictions of the provided object image, these restrictions of the provided image can therefore be compensated by the preliminary assignments such that the quality of the resulting element image can be improved.

Abstract: When generating a magnetic resonance (MR) attenuation map (39), an MR image is segmented to identify a patient's body outline, soft tissue structures, and ambiguous structures comprising bone and/or air. To distinguish between bone and air in the ambiguous structures, a nuclear emission image (e.g., PET) of the same patient or region of interest is segmented. The segmented functional image data is correlated to the segmented MR image data to distinguish between bone and air in the ambiguous structures. Appropriate radiation attenuation values are assigned respectively to identify air voxels and bone voxels in the segmented MR image, and an MR attenuation map is generated from the enhanced segmented MR image, in which ambiguity between air and bone has been resolved. The MR attenuation map is used to generate an attenuation-corrected nuclear image, which is displayed to a user.

Abstract: When compensating for truncated patient scan data acquired by a multi-modal PET/CT or PET/MR imaging system (14, 16), such as occurs when a patient is larger than a field of view for an anatomical imaging device, a segmented contour of a non-attenuation-corrected (NAC) PET image is used to identify a contour of the truncated region. An appropriate tissue type is used to fill in truncated regions of a truncated CT or MR image for the attenuation map. The corrected attenuation map is then used to generate an attenuation-corrected PET image of the patient or a region of interest. Alternatively, the system can be employed in PET/CT or PET/MR imaging scenarios where two modalities are performed sequentially (e.g., not simultaneously), and thus the contour derived from the PET scan can be compared to the CT or MR image to infer potential subject motion between the PET and CT or MR scans.

Abstract: A method of processing a positron emission tomography (PET) imaging data set (30) acquired of a subject includes independently localizing each positron-electron annihilation event of the PET imaging data set based on time of flight (TOF) localization of the positron-electron annihilation event to form a generated image (34). The generated image may be displayed. The generated image is suitably used as the basis for an initial image of an iterative reconstruction (40) of the PET imaging data set (30) to produce a reconstructed image (42). A spatial contour (56) of an image of the subject in the PET imaging data set (30) is suitably delineated based on the generated image (34). A subject attenuation map (62) for use in PET image reconstruction (40) is suitably constructed based in part on the spatial contour (56).

Abstract: A nuclear imaging system includes a crystal identification system which receives a flood image which includes a plurality of peaks, each peak responsive to radiation detected by a corresponding scintillator crystal. A crystal identification processor partitions the flood image into a plurality of candidate regions with a watershed segmentator implementing a watershed algorithm. The candidate regions are linked in an adjacency graph, and then classified as background or relevant, where relevant regions contain a peak within the watershed lines. The regions are then assigned to a crystal according to an objective function and an assignability score. A calibration processor maps the peaks to a rectangular grid.

Abstract: Methods, systems and apparatuses for processing data associated with nuclear medical imaging techniques are provided. Data is ordered in LUT's and memory structures. Articles of manufacture are provided for causing computers to carry out aspects of the invention. Data elements are ordered into a plurality of ordered data groups according to a spatial index order, and fetched and processed in the spatial index order. The data elements include sensitivity matrix elements, PET annihilation event data, and system and image matrix elements, the data grouped in orders corresponding to their processing. In one aspect geometric symmetry of a PET scanner FOV is used in ordering the data and processing. In one aspect a system matrix LUT comprises total number of system matrix elements equal to a total number of image matrix elements divided by a total number of possible third index values.

Abstract: When correcting attenuation in a nuclear image (e.g., PET or SPECT), an MR-based attenuation correction (AC) map (16) is generated using MR image data (14) of a subject (60). The subject (60) is then placed in a nuclear imaging device with a radioactive point or line source (18, 18?) from which transmission data is measured as the patient is imaged. In order to resolve ambiguity between air voxels and bone voxels in the MR-based AC map (16), estimated transmission data (24) is generated from the AC map and compared to the measured transmission data (22) from the point or line source. An error is iteratively calculated for the estimated and measured transmission data, and attenuation values of the AC map (16) are refined to minimize the error. The refined AC map (32) is used to correct attenuation in collected nuclear data (41) which is reconstructed into an attenuation corrected image (99) of the patient.

Abstract: A method of processing a positron emission tomography (PET) imaging data set (30) acquired of a subject includes independently localizing each positron-electron annihilation event of the PET imaging data set based on time of flight (TOF) localization of the positron-electron annihilation event to form a generated image (34). The generated image may be displayed. The generated image is suitably used as the basis for an initial image of an iterative reconstruction (40) of the PET imaging data set (30) to produce a reconstructed image (42). A spatial contour (56) of an image of the subject in the PET imaging data set (30) is suitably delineated based on the generated image (34). A subject attenuation map (62) for use in PET image reconstruction (40) is suitably constructed based in part on the spatial contour (56).

Abstract: Nuclear image data generated by a multimodal imaging device, such as a combined position emission tomography (PET)/magnetic resonance (MR) scanner (12, 14), is attenuation-corrected with a combined patient-specific attenuation correction (AC) map and an AC map template (70) for an MR coil (72) that is present in both the nuclear and MR scanning procedures. template library (46) contains templates for each of a plurality of MR coils and other accessories. Each template is generated on one of two manners. The coil may be imaged inside the PET scanner 14 with the transmission source 16 (e.g., Ge-68 or Cs-137). A transmission image 48 is reconstructed using the known algorithms and may be used as the AC template directly. Alternatively, the template can be generated by creating a global histogram of the transmission image and identifying segments of the coil or other accessory. An average linear attenuation coefficient (LAC) value is determined from the distribution of the histogram.

Abstract: A method and system for use in positron emission tomography, wherein a first processor element (234) is configured to reconstruct a plurality of positron annihilation events detected during a positron emission tomography scan using a list-based reconstruction technique to generate first volumetric data. A second reconstructor (226) is configured to reconstruct the plurality of events using a second reconstruction technique to generate second volumetric data for determining an error correction (228), the error correction applied to the first volumetric data to generate corrected volumetric data for generating a human-readable image (234). In one embodiment a multiplicative error correction is performed on the plurality of events, the first processor element (234) reconstructing the corrected plurality of events; and the second volumetric data error correction comprises an additive error correction.

Abstract: When correcting attenuation in a nuclear image (e.g., PET or SPECT), an MR-based attenuation correction (AC) map (16) is generated using MR image data (14) of a subject (60). The subject (60) is then placed in a nuclear imaging device with a radioactive point or line source (18, 18?) from which transmission data is measured as the patient is imaged. In order to resolve ambiguity between air voxels and bone voxels in the MR-based AC map (16), estimated transmission data (24) is generated from the AC map and compared to the measured trans-mission data (22) from the point or line source. An error is iteratively calculated for the estimated and measured transmission data, and attenuation values of the AC map (16) are refined to minimize the error. The refined AC map (32) is used to correct attenuation in collected nuclear data (41) which is reconstructed into an attenuation corrected image (99) of the patient.

Abstract: When compensating for truncated patient scan data acquired by a multi-modal PET/CT or PET/MR imaging system (14, 16), such as occurs when a patient is larger than a field of view for an anatomical imaging device, a segmented contour of a non-attenuation-corrected (NAC) PET image is used to identify a contour of the truncated region. An appropriate tissue type is used to fill in truncated regions of a truncated CT or MR image for the attenuation map. The corrected attenuation map is then used to generate an attenuation-corrected PET image of the patient or a region of interest. Alternatively, the system can be employed in PET/CT or PET/MR imaging scenarios where two modalities are performed sequentially (e.g., not simultaneously), and thus the contour derived from the PET scan can be compared to the CT or MR image to infer potential subject motion between the PET and CT or MR scans.

Abstract: An ultrasonic probe suitable for reducing reflected waves returning from a rear surface part to a transducer side, and an ultrasonic diagnostic apparatus. Ultrasonic probe 1 comprises transducer 10 transmitting and receiving ultrasonic waves to and from a subject, a backing material 12 disposed on the rear side of the transducer 10, and heat dissipating block 14 stacked on the backside of the backing material 12. At least one of the backing material 12 and heat-dissipating block 14 comprises void 16 therein. A sound absorbing material 18 is desirably filled in void 16.

Abstract: Methods, systems and apparatuses for processing data associated with nuclear medical imaging techniques are provided. Data is ordered in LUT's and memory structures. Articles of manufacture are provided for causing computers to carry out aspects of the invention. Data elements are ordered into a plurality of ordered data groups according to a spatial index order, and fetched and processed in the spatial index order. The data elements include sensitivity matrix elements, PET annihilation event data, and system and image matrix elements, the data grouped in orders corresponding to their processing. In one aspect geometric symmetry of a PET scanner FOV is used in ordering the data and processing. In one aspect a system matrix LUT comprises total number of system matrix elements equal to a total number of image matrix elements divided by a total number of possible third index values.