Abstract: A radiation therapy planning and follow-up system (10) includes an MR scanner (12) with a first bore (16) which defines an MR imaging region (18) and a functional scanner (26), e.g., a nuclear imaging scanner, or a CT scanner with a second bore (30) which defines a nuclear or CT imaging region (36). The first and second bores (16,30) have a diameter of at least 70 cm, and preferably 80-85 cm. A radiation therapy type couch (90) moves linearly through the MR imaging region (18) along an MR longitudinal axis and the nuclear or CT imaging region (36) along a nuclear or CT longitudinal axis which is aligned with the MR longitudinal axis. The couch positions a subject sequentially in the MR and nuclear or CT imaging regions (18, 36).

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 correcting for attenuation in a positron emission tomography (PET) image, a magnetic resonance (MR) image (24) of a subject is generated with spectroscopic data (38) describing the chemical composition of one or more of the voxels in the MR image. A table lookup is performed to identify a tissue type for each voxel based on the MR image data and spectral composition data, and an attenuation value is assigned to each voxel based on its tissue type to generate an MR attenuation correction (MRAC) map (30). The MRAC map (30) is used during reconstruction of the nuclear image (37) to correct for attenuation therein. Additionally, attenuation due to MR coils and other accessories that remain in a nuclear imager field of view during a combined MR/nuclear scan is corrected using pre-generated attenuation correction maps that are applied to a nuclear image after executing an MR scan to identify anatomical landmarks, which are used to align the pre-generated attenuation correction maps to the patient.

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 multiple modality imaging system (10) includes a MR scanner (12) which defines an MR imaging region (18), a nuclear imaging scanner (26) which defines a nuclear imaging region (34), an CT scanner (36) which defines an CT imaging region (42). Each scanner (12, 26, 36) having a longitudinal axis along which a common patient support (46) moves linearly through the MR, nuclear, and CT imaging regions (18, 34, 42). A marker (130, 140, 150), for use with the system (10), includes a radio-isotope marker (132) which is imageable by the nuclear imaging scanner (26) and the CT scanner (36) surrounded by a flexible silicone MR marker (134) which is imageable by the MR scanner (12) and the CT scanner (36). A calibration phantom (162), for use with the image scanner (10), includes a plurality of the markers (130, 140, 150) supported by a common frame having a known and predictable geometry.

Abstract: A radiation therapy planning and follow-up system (10) includes an MR scanner (12) with a first bore (16) which defines an MR imaging region (18) and a functional scanner (26), e.g., a nuclear imaging scanner, or a CT scanner with a second bore (30) which defines a nuclear or CT imaging region (36). The first and second bores (16,30) have a diameter of at least 70 cm, and preferably 80-85 cm. A radiation therapy type couch (90) moves linearly through the MR imaging region (18) along an MR longitudinal axis and the nuclear or CT imaging region (36) along a nuclear or CT longitudinal axis which is aligned with the MR longitudinal axis. The couch positions a subject sequentially in the MR and nuclear or CT imaging regions (18, 36).

Abstract: When correcting for attenuation in a positron emission tomography (PET) image, a magnetic resonance (MR) image (24) of a subject is generated with spectroscopic data (38) describing the chemical composition of one or more of the voxels in the MR image. A table lookup is performed to identify a tissue type for each voxel based on the MR image data and spectral composition data, and an attenuation value is assigned to each voxel based on its tissue type to generate an MR attenuation correction (MRAC) map (30). The MRAC map (30) is used during reconstruction of the nuclear image (37) to correct for attenuation therein. Additionally, attenuation due to MR coils and other accessories that remain in a nuclear imager field of view during a combined MR/nuclear scan is corrected using pre-generated attenuation correction maps that are applied to a nuclear image after executing an MR scan to identify anatomical landmarks, which are used to align the pre-generated attenuation correction maps to the patient.