JPH1043160A - Medical image diagnostic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To automatically start image pickup by stopping respiration at free timing based on the will of a subject by judging the stop of repiration from the waveform of a respiratory signal corresponding to respiratory movement and sending an image pickup starting command to an image pickup means. SOLUTION: A respiration detector 41 is attached to a subject 10, respiratory signals are converted to digital data by an A/D converter 42 and sent to a differentiation circuit 43 later, and the differentiation of digital data is found. When the reagent 10 stops breathing, the respiratory signal is turned from an ordinary regular change to the state of almost no change near '0'. Therefore, a breathing stop discrimination circuit 44 discriminates the state of stopping breathing by discriminating a differentiate signal provided by the differentiation circuit 43 gets lower than a fixed level. Then, when the stop of breathing is discriminated, the breathing stop discrimination circuit 44 sends the image pickup starting command to a sequence controller 25 and at such a time, the sequence controller 25 starts a prescribed image pickup pulse sequence.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a medical image diagnostic apparatus such as a nuclear magnetic resonance imaging apparatus.
In particular, the present invention relates to a medical image diagnostic apparatus that captures images while a subject holds his / her breath.

[0002]

2. Description of the Related Art Nuclear magnetic resonance imaging apparatus and X-ray CT
When imaging a subject with a medical image diagnostic device such as a device,
When the chest or abdomen is used as the imaging region, if the imaging region moves due to respiratory movement, a good image cannot be captured. Images may be taken during the operation.

In this case, conventionally, for example, an operator or the like uses a microphone to instruct the subject to perform preliminary breathing before holding his / her breath, and then instruct the subject to start holding his / her breath. Then, the operator confirms breath holding in the subject and performs a manual operation such as pressing an imaging start button.

[0004]

However, in the prior art, the subject must stop breathing according to instructions from the operator, and cannot breathe in the original rhythm. Therefore, a burden is imposed on the subject, for example, causing unnecessary tension. Some subjects may not be able to stop breathing as instructed, in which case only an image with degraded image quality will be obtained.

In view of the above, the present invention allows breathing to be stopped at any time according to the subject's intention, and automatically detects that breathing has been stopped without confirmation by an operator or the like. It is an object of the present invention to provide a medical image diagnostic apparatus improved to start imaging at a later time.

[0006]

In order to achieve the above object, in a medical image diagnostic apparatus according to the present invention, an image pickup means, a respiratory detection means for obtaining a respiratory signal corresponding to a respiratory movement, and a waveform of the respiratory signal And a breathing stop determining means for determining that the breathing has been stopped and giving an imaging start command to the imaging means.

[0007] A respiratory signal corresponding to the respiratory motion is obtained by the respiratory detecting means. By monitoring the respiratory signal waveform, the state of respiration can be known. Therefore, the respiratory arrest can be determined by capturing the amount of change in the waveform, the fluctuation width, the regularity, and the like. If an imaging start command is given to the imaging means in accordance with the determination of respiratory stop, the imaging can be automatically started in response to the stop of respiration. Therefore, the subject can stop breathing at his / her own discretion at his / her own will, and the burden is reduced. Further, the operation of confirming respiratory arrest by an operator or the like is not required.

[0008]

Next, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram showing an embodiment in which the present invention is applied to a nuclear magnetic resonance imaging apparatus. In this figure, a nuclear magnetic resonance imaging apparatus includes a main magnetic field (static magnetic field) generator 2
1 and a gradient magnetic field generator 22, and the subject 10 is inserted into these magnetic fields. The subject 10 is provided with a transmission coil 23 and a reception coil 24.

The gradient magnetic field generator 22 generates a gradient magnetic field in each of three orthogonal axes. The pulse waveform and timing of the gradient magnetic field in each axis are controlled by a sequence controller 25. Further, the sequence controller 25 controls the RF transmission device 26 to generate RF power obtained by amplitude-modulating a carrier having a resonance frequency with a predetermined waveform, and sends the RF power to the transmission coil 23. As a result, RF irradiation is performed on the subject 10.

The NMR signal generated in the subject 10 is received by a receiving coil 24 and sent to a receiving device 27, detected by a detecting circuit 28, converted to digital data by an A / D converter 29, and converted to digital data by a host computer 30. It is taken in. The host computer 30 performs image reconstruction processing such as two-dimensional Fourier transform of the collected data. The host computer 30 and the sequence controller 25 exchange data and commands.

The subject 10 is provided with a respiration detector 41. The respiration detector may be, for example, one that is attached to the abdomen and detects a tension thereof to obtain a signal corresponding to a change in abdominal pressure as a respiration signal. This respiratory signal is, for example, as shown in FIG. The respiratory signal is converted to digital data by the A / D converter 42 and then sent to the differentiating circuit 43. The differentiating circuit 43 calculates the derivative of the input digital data.
Obtaining the derivative corresponds to obtaining the amount of change (change rate) of the respiratory signal.

When the subject 10 holds his / her breath, the respiratory signal changes from a regular change as shown in the left part of FIG. . Therefore, if the breath holding determining circuit 44 determines that the differentiated signal obtained by the differentiating circuit 43 has fallen below a certain level,
The state of holding the breath can be determined. When it is determined that the breath is held, the breath holding determination circuit 44 issues an imaging start command as shown in FIG. 2B and sends it to the sequence controller 25. As a result, the sequence controller 25 starts a predetermined imaging pulse sequence including gradient magnetic field pulse generation, RF pulse transmission, and NMR signal reception from this time.

As described above, a breathing signal corresponding to a breathing motion is obtained, a breath hold is automatically determined from this breathing signal waveform, and a start command of an imaging pulse sequence is issued. You can hold your breath at any time. That is, even if the subject 10 holds his / her breath at any time, it is automatically determined and the imaging is automatically started. Therefore, the subject 10 does not follow the instructions of the operator and the like, and the burden is reduced. Further, the operator does not need to perform an operation of checking whether or not the breath is held. Thus, while reducing the burden on the subject 10 and the operator, it is possible to capture an image of excellent image quality without failure in a state where the breathing is always stopped.

The present invention can be variously modified without departing from the gist thereof. For example, in the above, the change amount is captured by taking the derivative of the respiration signal to determine that the breath is held, but when the breath is stopped, FIG.
Since the level of the respiratory signal stays near 0 as shown in, it may be determined from staying at the same signal level, or the regular change of the respiratory signal may be made using the regularity of the respiratory signal. It can also be configured to recognize the breath-hold on the basis of the correlation between the time period and the subsequent time period.

In the above description, the differentiating circuit 43 and the breath-holding determining circuit 44 are separately configured, but this does not mean that the configuration is limited to a hardware configuration, but a software configuration. May be. That is, this function may be loaded by a separately provided CPU, or processing corresponding to this function may be performed in the sequence controller 25 or the host computer 30.

The above-described imaging start command may be used to instruct the start of an entire sequence including a preprocessing sequence such as tuning. It is preferable that the command is a start command of a real imaging pulse sequence for the person 10.

In the above, an example in which the present invention is applied to a nuclear magnetic resonance imaging apparatus has been described. However, it is needless to say that the present invention can be applied to other medical image diagnostic apparatuses such as an X-ray CT apparatus.

[0018]

As described above, according to the medical image diagnostic apparatus of the present invention, the operation of the subject is extremely simple, the burden on the subject concerning breath holding is reduced, and an image having excellent image quality is stably obtained. Obtainable.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is a time chart illustrating operation.

[Explanation of symbols]

 REFERENCE SIGNS LIST 10 subject 21 main magnetic field generating device 22 gradient magnetic field generating device 23 transmitting coil 24 receiving coil 25 sequence controller 26 RF transmitting device 27 receiving device 28 detection circuit 29, 42 A / D converter 30 host computer 41 respiration detector 43 differentiation Circuit 44 Breath holding judgment circuit

Claims (1)

[Claims] An imaging unit, a respiration detecting unit for obtaining a respiration signal corresponding to a respiratory movement, a respiration stop which determines that respiration has been stopped from a waveform of the respiration signal and gives an imaging start command to the imaging unit A medical image diagnostic apparatus, comprising: a determination unit.