Electricity: measuring and testing – Particle precession resonance – Spectrometer components
Patent
1997-05-21
1999-08-03
Arana, Louis
Electricity: measuring and testing
Particle precession resonance
Spectrometer components
G01V 300
Patent
active
059330074
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to an MR device for determining the nuclear magnetization distribution in an examination zone by means of a cylindrical surface coil system which includes at least two coils which are constructed as respective loops. The invention also relates to a head coil system with a surface coil system which includes at least two coils which are constructed as respective loops.
2. Description of Related Art
The determination of the nuclear magnetization distribution in an examination zone by means of a surface coil system consisting of at least two surface coils offers the advantage that the signal-to-noise ratio is significantly enhanced in comparison with coils receiving spin resonance signals from the entire examination zone. A surface coil 10 system is known from Magnetic Resonance in Medicine 16, pp. 192-225, 1990. Therein, the images of the individual surface coils are combined so as to form an overall image by means of an appropriate method. It is a drawback of a surface coil system that its sensitivity is locally not uniform, i.e. that it is dependent on where in the examination zone the MR signal occurs.
A head coil system is known from 2nd SMR, Book of Abstracts, page 1103, 1994. Therein, a coil system which consists of six elements and can be wrapped around the head is supplemented by a butterfly coil which consists of two elements and is arranged on the skullcap of the patient. It is thus achieved that MR signals are also received from the area of the top of the head, but the sensitivity of the two butterfly elements is not very uniform so that problems are encountered when the individual images are combined so as to form an overall image. Moreover, two further receiving channels are required for the two butterfly elements.
SUMMARY OF THE INVENTION
It is an object of the present invention to enhance such an MR device in respect of sensitivity and resolution while using simple means. It is also an object of the invention to improve a head coil system of the kind set forth.
The former object is achieved according to the invention in that the coils are angular coils, part of the loop of which is bent towards the interior of the surface coil system.
The invention is based on the recognition of the fact that stronger MR signals can be received from an examination zone if the receiving coils are situated as near as possible to the object to be examined and cover an as large as possible part of the surface of this object.
The angular coils in the MR device according to the invention are bent so that they are situated as near as possible to the surface of the object to be examined. It is notably in the case of an MR device for examining the head, that the bent parts of the loops are situated directly over the top of the head. It is thus achieved that, in comparison with the known devices, substantially stronger MR signals can also be received from the upper area of the head. It is a particular advantage of the MR device according to the invention that no additional receiving channels are required, because the number of coils of the surface coil system can remain the same. It is merely that the coils are constructed as angular coils.
In a further embodiment of the invention the bent part of the loop is bent towards the interior of the surface coil system at an angle of no more than 90.degree.. When the loop parts are bent exactly through 90.degree., the MR device is particularly suitable for use as a head coil system. Thus, according to the invention the bent parts of the loops are situated in a common plane, resulting in a substantial enhancement of the homogeneity of the receiving profile of the MR device.
The angle coils in an embodiment of the invention are arranged on a coil support which is constructed as a straight circular cylinder. A particularly uniform receiving profile is thus also achieved within the cylinder, so that the MR device is particularly suitable for examination of the head.
In order to minimize the mutual coupli
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"The NMR Phased Array", Magnetic Resonance In Medicine 16, 192-225 (1990), P.B. Roemer, W.A. Edelstein, C.E. Hayes, S.P. Souza, O.M. Mueller.
"An 8-Element Cortical Top Head Coil Array", 2nd SMR, Philips Research, Department Technical Systems, Hamburg Germany, C. Leussler, p. 1103, 1994.
Leussler Christoph
Schommer Jan
Arana Louis
Renfrew, Jr. Dwight H.
U.S. Philips Corporation
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