Biomagnetic field measuring apparatus

• US 6,269,262 B1
• Filed: 06/15/1998
• Issued: 07/31/2001
• Est. Priority Date: 06/20/1997
• Status: Expired due to Term

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Kandori, Akihiko, Suzuki, Hiroyuki, Tsukada, Keiji, Shinomura, Ryuichi, Teshigawara, Kenji, Kondo, Shoji, Sasabuchi, Hitoshi, Komiyama, Yasuaki
• Primary Examiner(s): Vo, Peter
• Assistant Examiner(s): Lin, Jeoyuh
• Application Number:
  US09/094,690
• Time in Patent Office: 1,142 Days
• Field of Search: 600/407, 600/404, 600/425, 600/481, 600/508, 600/512, 600/513, 600/523, 600/524, 600/437, 600/440, 600/444, 600/450, 600/509, 600/511, 600/443
• US Class Current: 600/409
• CPC Class Codes: A61B 5/0046 Arrangements of imaging apparatus in a room, e.g. room provided with shielding or for improved access to apparatus
• CPC Class Codes: A61B 5/242 Detecting biomagnetic fields, e.g. magnetic fields produced by bioelectric currents
• CPC Class Codes: A61B 8/4416 related to combined acquisition of different diagnostic modalities, e.g. combination of ultrasound and X-ray acquisitions

Abstract

A biomagnetic field measurement apparatus includes a bed which holds a subject to be inspected in a shielded room. A cryostat holds a plurality of SQUID magnetometers at low temperature. The cryostat is arranged in the shielded room and the plurality of SQUID magnetometers detect a magnetic field generated from the subject. A driving and detecting circuit drives the plurality of SQUID magnetometers and detects signals therefrom that are processed by a computer. A display that is arranged in the shielded room displays data for viewing by an operator.

Claims

1. A biomagnetic field measurement apparatus comprising:

a shielded room;

a bed which is adapted to hold a subject to be inspected in said shielded room;

a cryostat in which a plurality of SQUID magnetometers are arranged at low temperature, wherein said cryostat is arranged in said shielded room and the plurality of SQUID magnetometers detect a normal component of a magnetic field generated from a heart of a fetus in said subject to be inspected;

a gantry which is adapted to hold said cryostat, and which is arranged in said shielded room;

a driving and detecting circuit which drives the plurality of SQUID magnetometers and detects signals from the plurality of SQUID magnetometers;

an electrocardiograph which is used to obtain an electrocardiogram of said subject to be inspected, wherein the measure of said electrocardiogram and the measurement of the normal component of said magnetic field are carried out simultaneously;

a computer which collects the signals from said driving and detecting circuit and collects signals from said electrocardiograph, and processes the signals from said driving and detecting circuit to obtain a magnetic field waveform expressing a temporal change of said magnetic field, and to obtain a distribution of the magnetic field in the heart of the fetus and a distribution of an electric current in the heart of the fetus, wherein said computer calculates said distribution of the magnetic field by an equation of {square root over ((dB_z+L /dx)²+L +(dB_z+L /dy)²+L )}, where (x, y, z) are Cartesian coordinates and B_z is said normal component of said magnetic field, and calculates said distribution of the electric current by 90°

counter-clockwise rotation of a vector of the differential values (dB_z/dx, dB_z/dy); and

a display which displays said magnetic field waveform and which is arranged in said shielded room such that an operator positioning a lower surface of said cryostat with respect to said subject to be inspected can observe said magnetic field waveform on said display.

2. A biomagnetic field measurement apparatus comprising:

a shielded room;

a bed which is adapted to hold a subject to be inspected in said shielded room;

a cryostat in which a plurality of SQUID magnetometers are arranged at low temperature, wherein said cryostat is arranged in said shielded room and the plurality of SQUID magnetometers detect a magnetic field generated from a heart of a fetus in said subject to be inspected, and a lower surface of said cryostat is arranged near or on a surface of the lower abdomen of said subject to be inspected;

a gantry which is adapted to hold said cryostat in said shielded room;

a driving and detecting circuit which drives the plurality of SQUID magnetometers and detects signals from the plurality of SQUID magnetometers;

a computer which collects the signals from said driving and detecting circuit and which processes the signals from said driving and detecting circuit to obtain a magnetic field waveform expressing a temporal change of said magnetic field;

an ultrasonic transducer probe arranged in said shielded room;

a main body of an ultrasonic diagnosis apparatus which comprises a transmitting circuit and a processor, and which is arranged outside of said shielded room, wherein said transmitting circuit drives said ultrasonic transducer probe and said ultrasonic transducer probe transmits an ultrasound wave to the heart of the fetus of said subject to be inspected, and said processor processes reflected ultrasound waves from the heart of the fetus, to obtain an ultrasonic image of the fetus, and said reflected ultrasound waves are received by said ultrasonic transducer probe;

a probe holder which is adapted to hold said ultrasonic transducer probe and to bring a surface of said ultrasonic transducer probe into contact with the surface of the lower abdomen of said subject to be inspected, and which is arranged on said bed or said gantry; and

a display which is arranged in said shielded room and displays said ultrasonic image of the fetus.

3. A biomagnetic field measurement apparatus comprising:

a shielded room;

a bed which is adapted to hold a subject to be inspected in said shielded room;

a cryostat in which a plurality of SQUID magnetometers are arranged at low temperature, wherein said cryostat is arranged in said shielded room, and the plurality of SQUID magnetometers detect a normal component of a magnetic field generated from a heart of a fetus in said subject to be inspected, and a lower surface of said cryostat is arranged near or on a surface of the lower abdomen of said subject to be inspected;

a gantry which is adapted to hold said cryostat in said shielded room;

a driving and detecting circuit which drives the plurality of SQUID magnetometers and detects signals from the plurality of SQUID magnetometers;

a computer which collects the signals from said driving and detecting circuit and which processes the signals from said driving and detecting circuit to obtain a magnetic of the magnetic field in the heart of said fetus in said subject to be inspected, wherein said computer calculates said distribution of the magnetic field by an equation of {square root over ((dB_z+L /dx)²+L +(dB_z+L /dy)²+L )}, where (x, y, z) are Cartesian coordinates and B_z is said normal component of said magnetic field; and

a display which is arranged in said shielded room and displays said distribution of the magnetic field.