Surgery – Diagnostic testing – Detecting nuclear – electromagnetic – or ultrasonic radiation
Reexamination Certificate
1998-06-15
2001-07-31
Vo, Peter (Department: 3737)
Surgery
Diagnostic testing
Detecting nuclear, electromagnetic, or ultrasonic radiation
C600S425000, C600S481000, C600S508000, C600S511000, C600S513000, C600S514000, C324S248000, C324S260000, C324S262000
Reexamination Certificate
active
06269262
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a biomagnetic field measuring apparatus using superconducting quantum interference device (SQUID) magnetometers for performing measurement of a magnetic field generated from the heart of an adult, child or foetus, and more particularly relates to a biomagnetic field measuring apparatus in which an ultrasonic transducer probe is arranged inside a shielded room, an ultrasonic tomographic image of a subject to be inspected and a waveform of a magnetic field generated from the heart of the inspected subject are displayed inside the shielded room, and the start of measurement of a biomagnetic field is controlled in the shielded room.
For diagnosis of heart disease of a foetus, ultrasonic examination has widely been used which can detect the shape and rough motion of the heart and the state of blood flow in the heart, but in the ultrasonic examination, cardiac activity of the heart muscle cannot be detected.
In the conventional biomagnetic field measurement, a waveform monitor unit is arranged outside a shielded room and an operator cannot confirm waveforms in the shielded room. Especially in the case of a magnetic field generated from the heart of foetus, the position of which is unstable, is desired to be detected, the operator must get information from a person who operates the monitor unit disposed outside the shielded room and determine a measuring location (Rev. Sci. Instrum. 66 (10), pp. 5085-5091 (1995)).
By measuring a magnetic field generated from the heart (hereinafter called a cardiac magnetic field) through the use of a biomagnetic field measuring apparatus, cardiac muscle activity can be diagnosed. On the other hand, with an ultrasonic diagnosis apparatus, the state of blood flow in the heart can be diagnosed.
In the conventional biomagnetic field measurement, much time is consumed to search a measuring location, raising a problem that magnetic field measurement at an optimum location is difficult to achieve. Further, a control unit for SQUID magnetometers and a unit for acquisition control of magnetic field waveforms are arranged outside the shielded room and therefore, there is a problem that a magnetic field waveform cannot be recorded within the most optimum time zone.
For the purpose of accurately diagnosing a heart disease, a result of measurement of a cardiac magnetic field and a result by the ultrasonic diagnosis apparatus which are obtained at substantially the same time must be correlated to each other to conduct diagnosis collectively. But when the conventional ultrasonic diagnosis apparatus using many magnetic materials is arranged in the shielded room, magnetic noise is generated and therefore the conventional ultrasonic diagnosis apparatus cannot be arranged inside the shielded room where the biomagnetic field measuring apparatus is arranged, thus raising a problem that an inspection based on the ultrasonic diagnosis apparatus cannot be carried out simultaneously with the measurement of the cardiac magnetic field.
In measurement of a very weak magnetic field generated from the heart of a foetus, it is necessary to approach a pickup coil of the biomagnetic field measuring apparatus to the heart of the foetus as closely as possible. But the foetus moves in the uterus and therefore, the position of the heart of the foetus is desired to be confirmed by means of the ultrasonic diagnosis apparatus, which can perform noninvasive diagnosis immediately before a magnetic field generated from the heart of the foetus is measured. Thus, the use of the ultrasonic diagnosis apparatus inside the shielded room has been desired strongly.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a biomagnetic field measuring apparatus which can control, inside the shielded room, the start of observation of magnetic field waveforms measured from the heart of a subject to be inspected, magnetic field distribution and electric current distribution determined by computation and the measurement of the magnetic field waveforms and which can quickly position the sensors to optimum measuring locations.
Another object of the present invention is to provide an apparatus which can perform measurement of a biomagnetic field concurrently with ultrasonic inspection inside the shielded room.
A biomagnetic field measuring apparatus according to the present invention has, in a shielded room, a display for monitoring a magnetic field waveform generated from a heart of a foetus inside a subject to be inspected and magnetic field distribution and electric current distribution in the heart, a loudspeaker for generating a sound in synchronism with a heart beat of the heart, SQUID magnetometers, a switch for performing acquisition control of the magnetic field waveform, means for moving a bed, means for moving a gantry holding a cryostat, and an air mat for upward and downward motion of part of the inspected subject on the bed.
According to the biomagnetic field measuring apparatus according to the present invention, an operator inside the shielded room can observe, on a real time basis, magnetic field waveforms generated from the heart of the foetus inside the inspected subject in the form of a display picture on the display. As a result, the operator adapts SQUID magnetometers on the inspected subject so as to detect a maximum signal.
In the apparatus of the present invention, an ultrasonic transducer probe of the ultrasonic diagnosis apparatus is arranged inside the shielded room, a main body of the ultrasonic diagnosis apparatus including a transmitting circuit for transmission of an ultrasonic wave and a processor for receiving the ultrasonic wave and processing the received signal is arranged outside the shielded room, and an ultrasonic tomographic image is displayed on the display arranged inside the shielded room.
With the construction of the present invention which can permit confirmation of the results of measurement of the biomagnetic field and an ultrasonic tomographic image of the foetus in the inspected subject inside the shielded room, the operator inside the shielded room can observe the position of the heart of the foetus through the ultrasonic tomographic image on a substantially real time base when the magnetic field generated from the heart of the foetus is measured and consequently, the SQUID magnetometers can be positioned quickly to optimum measuring locations and the magnetic field generated from the heart of the foetus can be detected clearly with high sensitivity. When a magnetic field generated from an adult or a child is measured, the cardiac magnetic field can be measured while simultaneously observing a blood flow state in the heart through an ultrasonic tomographic image.
According to the biomagnetic field measuring apparatus according to the present invention, an abnormality of the heart of the foetus such as arrhythmia can be detected to permit early diagnosis of heart disease and important information about prenatal therapy and afterbirth therapy can be obtained.
As shown in
FIGS. 1 and 7
, the biomagnetic field measuring apparatus comprises a shielded room
1
, a bed
4
, SQUID magnetometers for detecting a magnetic field from a subject to be inspected, a cryostat
2
for maintaining the SQUID magnetometers at an extremely low temperature (liquid helium He temperature or liquid nitrogen temperature), gantry
180
for holding the cryostat, and a computer
90
for driving the SQUID magnetometers and acquiring outputs of driving detection circuit
50
for detecting signals from the SQUID magnetometers to perform computation. There are provided in the shielded room means (monitor display
80
) for displaying one or more of a measured magnetic field waveform, measured electrocardiogram waveform, distribution of magnetic field obtained through computation and distribution of electric current obtained through computation, a SQUID magnetometer driving button
19
a
for controlling operation of the SQUID magnetometers, a data acquisition starting button
19
b
for controlling start of data acq
Kandori Akihiko
Komiyama Yasuaki
Kondo Shoji
Sasabuchi Hitoshi
Shinomura Ryuichi
Hitachi , Ltd.
Lin Jeoyuh
Mattingly Stanger & Malur, P.C.
Vo Peter
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