Abstract: A novel MR method and system is described for using MR images for planning radiotherapy treatment. The images are obtained by a scanner which generates a magnetic field with a magnetic center (isocenter). First at least one fiducial marker (4; 5) is applied to the body (1) of the patient at a predetermined distance from the isocenter. The patient is repositioned within said scanner such that an anatomical target (2) is located in close vicinity of said isocenter. A first image of said target (2) is obtained and then the patient (1) is shifted such that the fiducial marker (4; 5) is close to the isocenter. A second image is obtained at the shifted position, in which the fiducial marker has an accurate geometrical position, that is merged into said first image.

Abstract: Anatomical matching of images acquired by different imaging modalities plays an important role in diagnostic medical imaging. In common medical practice such matching takes place after the acquisition of the data sets containing the information to be matched and while utilizing standard post-processing algorithms. The invention provides a method for the acquisition of anatomically matched images while using the information concerning the position and orientation of the first imaging modality relative to the object. Upon selection of a relevant image from the primary data set acquired by means of the first imaging modality, the co-ordinates which unambiguously define the position of the first imaging apparatus relative to this image are defined. These co-ordinates are made available to the second imaging modality which is adjusted in conformity therewith. The image acquired by the second imaging modality will thus be anatomatically matched with the primary image.

Abstract: The invention relates to an MR imaging method in which the parallel acquisition of the MR data, for example in conformity with the SMASH or SENSE methods, is performed by means of a plurality of receiving coils. The different spatial sensitivity profiles of the receiving coils are used for the image reconstruction. When the sensitivity data used during the image reconstruction do not correspond to the position in space of the receiving coils during the image acquisition, undesirable image artifacts will occur. In accordance with the invention such artifacts are eliminated by (virtually) adapting the spatial sensitivity profiles automatically during the image reconstruction.

Abstract: An interventional magnetic resonance method and apparatus utilizing a microcoil which enable localization of an interventional instrument by detecting magnetic resonance signals from the surroundings of the microcoil under the influence of magnetic field gradients. The outstanding reliability and the high speed of the method are due to the application of spatially non-selective RF pulses in conjunction with a sequence of gradient pulses in non-colinear directions. The localization method can be used inter alia for angiography wherein the signal intensity is used to determine the amount of blood present in the blood vessel.

Abstract: An invasive device 17, such as a catheter, is connected to a supply and control unit via a connection conductor 21 for the transfer of power supply energy and/or LF signals to and from an electrical circuit 20 in the distal part 18 of the device. During operation the connection conductor traverses the homogeneous magnetic field and the RF field of the MRI apparatus; this may give rise to heating of the connection conductor and/or to a disturbance of said fields. In order to mitigate these drawbacks, the connection conductor in accordance with the invention is subdivided into mutually separated segments 22-i, each of which is much shorter (for example, 1/20) than the wavelength of the RE field in the apparatus; the segments are separated from one another by separating elements 23-i (self-inductances) that provide a high inductance for said RF frequencies and a low inductance for comparatively low frequencies.

Abstract: A method of forming a magnetic resonance image involves separate measurement of the position of a measuring site. The magnetic resonance image is corrected on the basis of the measured position of the measuring site.

Abstract: A magnetic resonance method for forming a fast dynamic image from a plurality of signals of an RF probe is described. The RF probe is moved relative to an object to be imaged so as to acquire at least two adjacent Fields-of-View (FOV) which are reconstructed so as to form an image of a region of interest which includes both FOVs. The object to be imaged is scanned by a moving RF antenna. Furthermore, the first FOV is centered at the initial probe position and after each subsequent scan the position of the imaging field within the actual FOV is determined. From that data the next position of the RF probe relative to the object is computed and, if the imaging field runs out of the actual FOV, the RF antenna is moved to the estimated next position of the RF probe so that the subsequent FOV is centered again at the RF probe position. A composite image is then generated from the successive images of the various adjacent FOVs.

Abstract: In a method for acquiring an image of a plane in a magnetic resonance apparatus, the images are obtained in imaging planes which are defined directly with respect to the patient. The magnetic resonance apparatus includes an imaging volume, a patient support table which positioned in the imaging volume, a position measuring device to establish and maintain in real time the position of the patient, as well as a controller for controlling gradient coils in response to the signals provided by the position measuring device in such a manner that consecutive images are acquired from imaging planes which are defined directly with respect to the patient.

Abstract: In interventional MRI, for example, in neurosurgical applications, the head of a patient must be positioned on a head support while allowing reproducible manipulation of the head. The head support must be made of a material that is compatible with MR. Furthermore, spatial restrictions imposed by the bore of the magnetic resonance apparatus have to be dealt with. The head support in accordance with the invention includes a support whereon the patient head or a stereotactic frame can be rested. The head support is suppored by a mounting device. Both the support and mounting device are fixed on the table top. The mounting device provides a sliding surface that enables rotation of the support relative to the mounting device. The support can be curved towards the table top thus providing a concave surface so as to lower the supporting surface for a stereotactic frame and hence to minimize the total volume of the construction.

Abstract: The invention relates to a method enabling the localization of objects, for example surgical instruments, in interventional radiology. The method utilizes the known geometrical shape of the object to be localized in order to simulate projections therefrom for comparison with real projection images. Optimum correspondence between simulation and real image yields the desired object position and object orientation. The invention is based on digital image processing and can be used in conjunction with customary radiological diagnostic apparatus such as C-arm fluoroscopy apparatus, computed tomography apparatus or magnetic resonance tomography apparatus. Objects to be localized can be provided with markers whose spatial position yields an unambiguous projection image.

Abstract: The invention relates to an interventional magnetic resonance method utilizing a microcoil. The method enables localization of an interventional instrument by detection of magnetic resonance signals from the surroundings of the microcoil under the influence of magnetic field gradients. The outstanding reliability and the high speed of the method are due to the application of spatially non-selective RF pulses in conjunction with a sequence of gradient pulses in non-colinear directions. The localization method can be used inter alia for angiography wherein the signal intensity is used to determine the amount of blood present in the blood vessel. The invention also relates to a magnetic resonance apparatus for carrying out the method.

Abstract: An invasive device 17, such as a catheter, is connected to a supply and control unit via a connection conductor 21 for the transfer of power supply energy and/or LF signals to and from an electrical circuit 20 in the distal part 18 of the device. During operation the connection conductor traverses the homogeneous magnetic field and the RF field of the MRI apparatus; this may give rise to heating of the connection conductor and/or to a disturbance of said fields. In order to mitigate these drawbacks, the connection conductor in accordance with the invention is subdivided into mutually separated segments 22-i, each of which is much shorter (for example, 1/20) than the wavelength of the RF field in the apparatus; the segments are separated from one another by separating elements 23-i (self-inductances) that provide a high inductance for said RF frequencies and a low inductance for comparatively low frequencies.

Abstract: The invention relates to an MR imaging method in which the parallel acquisition of the MR data, for example in conformity with the SMASH or SENSE methods, is performed by means of a plurality of receiving coils. The different spatial sensitivity profiles of the receiving coils are used for the image reconstruction. When the sensitivity data used during the image reconstruction do not correspond to the position in space of the receiving coils during the image acquisition, undesirable image artifacts will occur. In accordance with the invention such artifacts are eliminated by (virtually) adapting the spatial sensitivity profiles automatically during the image reconstruction.

Abstract: In a method for acquiring an image of a plane in a magnetic resonance apparatus the images are obtained in planes to be imaged which are defined directly with respect to the patient. Therefore, the magnetic resonance apparatus comprises an imaging volume and a patient support table which can be positioned in this imaging volume, position measuring means being provided so as to establish and maintain in real time the position of the patient as well as control means for controlling gradient coils in response to the signals provided by the position measuring means in such a manner that the consecutive images are acquired from imaging planes which are defined directly with respect to the patient.

Abstract: A magnetic resonance method for forming a fast dynamic image from a plurality of signals of an RF probe is described. The RF probe is moved relative to an object to be imaged so as to acquire at least two adjacent Fields-of-View (FOV) which are reconstructed so as to form an image of a region of interest which includes both FOVs. The object to be imaged is scanned by a moving RF antenna. Furthermore, the first FOV is centered at the initial probe position and after each subsequent scan the position of the imaging field within the actual FOV is determined. From that data the next position of the RF probe relative to the object is computed and, if the imaging field runs out of the actual FOV, the RF antenna is moved to the estimated next position of the RF probe so that the subsequent FOV is centered again at the RF probe position. A composite image is then generated from the successive images of the various adjacent FOVs.

Abstract: Anatomical matching of images acquired by different imaging modalities plays an important role in diagnostic medical imaging. In common medical practice such matching takes place after the acquisition of the data sets containing the information to be matched and while utilizing standard post-processing algorithms. The invention provides a method for the acquisition of anatomically matched images while using the information concerning the position and orientation of the first imaging modality (1) relative to the object. Upon selection of a relevant image from the primary data set acquired by means of the first imaging modality, the co-ordinates which unambiguously define the position of the first imaging apparatus relative to this image are defined. These co-ordinates are made available to the second imaging modality (2) which is adjusted in conformity therewith. The image acquired by the second imaging modality will thus be anatomatically matched with the primary image.

Abstract: In interventional MRI, for example, in neurosurgical applications, the head of a patient must be positioned on a head support while allowing reproducible manipulation of the head. The head support must be made of a material that is compatible with MR. Furthermore, spatial restrictions imposed by the bore of the magnetic resonance apparatus have to be dealt with The head support (15) in accordance with the invention comprises supporting means (1) whereon the patient head or a stereotactic frame can be rested. The supporting means (1) rest on the mounting means (2) and are fixed on the table top thereby. The mounting means (2) provide a sliding surface (16) that enables rotation of the supporting means (1) relative to the mounting means (2). The supporting means (1) can be curved towards the table top on which they rest, thus providing a concave surface (9) so as to lower the supporting surface for a stereotactic frame and hence minimize the total volume of the construction.

Abstract: The invention relates to a method enabling the localization of objects, for example surgical instruments, in interventional radiology. The method utilizes the known geometrical shape of the object to be localized in order to simulate projections therefrom for comparison with real projection images. Optimum correspondence between simulation and real image yields the desired object position and object orientation. The invention is based on digital image processing and can be used in conjunction with customary radiological diagnostic apparatus such as C-arm fluoroscopy apparatus, computed tomography apparatus or magnetic resonance tomography apparatus. Objects to be localized can be provided with markers whose spatial position yields an unambiguous projection image.