Permanent magnet for NMR image detection

A permanent magnet for nuclear magnetic resonance image detection, which magnet comprises:

• a magnetic structure having a yoke and magnetic poles, so shaped as to delimit or enclose a cavity, at least a part of a volume of the cavity forms a compartment for receiving at least a part of a body under examination, and at least a part of the volume of the cavity is permeated by a static magnetic field having specific intensity and homogeneity characteristics;
• the magnetic structure has at least one open side, parallel to the static magnetic field;
• the magnetic structure has at least two opposite main poles, lying face to face, transverse to the open side, the static magnetic field being generated therebetween;
• in the vicinity of the open side, the magnet has means for correcting the static magnetic field generated between the main poles, the correction means including means for increasing the magnetic potential near the open side, and over a predetermined depth therefrom, transverse to the open side, without reducing the span of the opening;
• wherein the correcting means includes, at the open side, a pair of opposite auxiliary poles, inwardly penetrating over a predetermined distance towards their respective main poles, which auxiliary poles are provided with magnetized material, and
• the magnetized material associated with the auxiliary poles is equal as regards quantity and type to the magnetized material associated with the main poles, and between the main pole and the adjacent auxiliary pole, a magnetized insert is interposed, so as to generate a magnetic potential difference between the main poles and the adjacent auxiliary poles, whereby the magnetic potential of the auxiliary poles is increased with respect to the potential of the main pole.

A permanent magnet for nuclear magnetic resonance image detection, which magnet comprises:

• a magnetic structure having a yoke and magnetic poles, so shaped as to delimit or enclose a cavity, at least a part of a volume of the cavity forms a compartment for receiving at least a part of a body under examination, and at least a part of the volume of the cavity is permeated by a static magnetic field having specific intensity and homogeneity characteristics;
• the magnetic structure has at least one open side, parallel to the static magnetic field;
• the magnetic structure has at least two opposite main poles, lying face to face, transverse to the open side, the static magnetic field being generated therebetween;
• in the vicinity of the open side, the magnet has at the open side, a pair of opposite auxiliary poles, inwardly penetrating over a predetermined distance towards their respective main poles, which auxiliary poles are provided with magnetized material for increasing the magnetic potential near the open side, and over a predetermined depth therefrom, transverse to the open side, without reducing the span of the opening;
• wherein the main poles and the auxiliary poles have parallel magnetization vectors, oriented in the same direction.

A permanent magnet for nuclear magnetic resonance image detection, which magnet comprises:

• a magnetic structure having a yoke and magnetic poles, so shaped as to delimit or enclose a cavity, at least a part of a volume of the cavity forms a compartment for receiving at least a part of a body under examination, and at least a part of the volume of the cavity is permeated by a static magnetic field having specific intensity and homogeneity characteristics;
• the magnetic structure has at least one open side, parallel to the static magnetic field;
• the magnetic structure has at least two opposite main poles, lying face to face, transverse to the open side, the static magnetic field being generated therebetween;
• in the vicinity of the open side, the magnet has at the open side, a pair of opposite auxiliary poles, inwardly penetrating over a predetermined distance towards their respective main poles, which auxiliary poles are provided with magnetized material for increasing the magnetic potential near the open side, and over a predetermined depth therefrom, transverse to the open side;
• and
• a distance between the pair of auxiliary poles being greater than a distance between the two opposite main poles so as to enable easy access to the compartment.

A permanent magnet for nuclear magnetic resonance image detection, which magnet comprises:

• a magnetic structure having a yoke and magnetic poles, so shaped as to delimit or enclose a cavity, at least a part of a volume of the cavity forms a compartment for receiving at least a part of a body under examination, and at least a part of the volume of the cavity is permeated by a static magnetic field having specific intensity and homogeneity characteristics;
• the magnetic structure has at least one open side, parallel to the static magnetic field;
• the magnetic structure has at least two opposite main poles, lying face to face, transverse to the open side, the static magnetic field being generated therebetween;
• in the vicinity of the open side, the magnet has means for correcting the static magnetic field generated between the main poles, the correction means including means for increasing the magnetic potential near the open side, and over a predetermined depth therefrom, transverse to the open side, without reducing the span of the opening;
• wherein the correcting means includes, at the open side, a pair of opposite auxiliary poles, inwardly penetrating over a predetermined distance towards their respective main poles, which auxiliary poles are provided with magnetized material, and
• the magnetized material associated with the auxiliary poles is in a larger quantity and of a different quality with respect to the magnetized material associated with the main poles, in such a way as to obtain an increase of the magnetic potential in the area between the auxiliary poles with respect to that between the main poles.