Electricity: measuring and testing – Particle precession resonance – Using a nuclear resonance spectrometer system
Reexamination Certificate
1999-04-14
2001-04-10
Oda, Christine (Department: 2862)
Electricity: measuring and testing
Particle precession resonance
Using a nuclear resonance spectrometer system
C324S307000, C324S300000
Reexamination Certificate
active
06215305
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a magnetic resonance (MR) method for imaging a part of a human or animal body which is arranged in a steady magnetic field, which method includes the following steps:
image of the second imaging plane of the part, a first cross-section of said part being reproduced in the first MR image whereas a second cross-section of said part is reproduced in the second MR image,
forming a third MR image of the third imaging plane from information of the first and second MR images. 2. Description of Related Art
The invention also relates to an MR device for carrying out such a method.
An imaging plane is to be understood to mean herein a slice of the body which is visualized by means of an MR image.
A method of this kind is known from U.S. Pat. No. 5,514,962. The known method is used to form MR images for a functional analysis of a part of the body, for example a heart of the human or animal body. In order, it is used to form perfusion MR images of the heart or MR images of the coronary artery system around the heart. In such cases it is important to image an as large as possible part of a coronary artery. Because measurement of MR signals often utilizes a technique which requires a patient to hold his or her breath during a measurement, it is important that an appropriate orientation of the third imaging plane is found as quickly as possible in order to reduce discomfort to the patient.
To this end, according to the known method imaging information is measured and a three-dimensional model of the part of the body is displayed on a monitor by means of a workstation. In order to determine the third imaging plane of the third image, reproducing most of the part, an auxiliary plane is subsequently displayed on the monitor. Subsequently, the operator shifts the auxiliary plane, by way of translation and rotation of the auxiliary plane, in such a manner that the auxiliary plane displayed on the monitor intersects the three-dimensional model for a largest part. The co-ordinates of the auxiliary plane thus found subsequently determine the co-ordinates of the third imaging plane. During a next step MR signals are measured for the reconstruction of the third MR image of the third imaging plane of the part. It is a drawback of the known method that a large amount of time is required in order to determine a three-dimensional model of adequate resolution. Examples of parts of the body having a small cross-section are, for example parts of the coronary artery which have a cross-section of approximately 1 mm.
SUMMARY OF THE INVENTION
It is an object of the invention to reduce the amount of time required to display the third imaging plane of an as large as possible part of the body which extends between the first and the second imaging plane. To achieve this, the method according to the invention is characterized in that the determination of a third imaging plane involves the determination of two points of the third imaging plane by a first point of the first cross-section of the part in the first MR image and a second point of the second cross-section of the part in the second MR image. The invention is based on the recognition of the fact that the determination of two points of the third imaging plane being the first point of the first cross-section of the part with the first imaging plane and the second point of the second cross-section of the part of the second imaging plane, respectively, and a third point to be selected defines the third imaging plane in such a manner that the part is most largely imaged. An operator can simply indicate said first and second points in the first cross-section of the part in the first MR image and the second cross-section of the part in the second MR image. The co-ordinates of the first, the second and the third point are subsequently converted into adjusting parameters for an MR imaging pulse sequence for the measurement of MR signals for the reconstruction of the third MR image of the third imaging plane.
A special version of the method according to the invention is characterized in that the first and the second imaging plane are chosen so as to extend in parallel.
A further version of the method according to the invention is characterized in that it also includes steps for forming a fourth MR image of the fourth imaging plane of the part of the body, thus imaging a fourth cross-section of the part in which a third point of the third imaging plane is furthermore determined by a point of the fourth cross-section of the part in the fourth MR image. The third imaging plane is thus completely defined, so that the chances of the third imaging plane containing a complete cross-section of the part are enhanced. The third imaging plane thus defined then contains parts of the coronary artery of said three imaging planes and, unless the coronary artery is strongly curved, also the parts between said parts.
A further version of the method according to the invention is characterized in that an MR image is formed of a corrected imaging plane whose co-ordinates are determined by a translation in a direction of the third imaging plane or by a rotation about an axis of the third imaging plane.
An MR device for magnetic resonance imaging of a part of a human or animal body to be arranged in the device, which MR device also includes:
means for sustaining the steady magnetic field,
means for generating RF pulses,
means for generating gradients in the steady magnetic field,
a control unit for generating control signals for the means for generating RF pulses and the means for generating the gradients,
means for measuring MR signals,
means for reconstructing a first MR image and a second MR image from the measured MR signals from a first imaging plane and a second imaging plane, respectively, of a part of the body to be arranged in the MR device, a first cross-section of said part being reproduced in the first MR image whereas a second cross-section is reproduced in the second MR image,
means for determining a third imaging plane of a third cross-section of the first part, and
means for reconstructing a third MR image of the third imaging plane,
characterized in that the means for determining a third imaging plane are arranged in such a manner that two points of the third imaging plane are determined by a first point of the first cross-section of the part in the first MR image and a second point of the second cross-section of the part in the second MR image.
REFERENCES:
patent: 4674046 (1987-06-01), Ozeki et al.
patent: 5323111 (1994-06-01), Suzuki
patent: 5512827 (1996-04-01), Hardy et al.
patent: 5514962 (1996-05-01), Cline et al.
De Becker Jan F. L.
Haselhoff Eltjo H.
Oda Christine
Shrivastav Brij B.
U.S. Philips Corporation
Vodopia John F.
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