Patent Application
20180085007
This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2016-186191, filed on Sep. 23, 2016 and Japanese Patent Application No. 2017-182918, filed on Sep. 22, 2017; the entire contents of which are incorporated herein by reference.
Embodiments described herein relate generally to a magnetic resonance imaging apparatus.
A T1 map displaying T1 of a tissue is considered to be effective for diagnosis of, for example, diffuse myocardial fibrosis. As a magnetic resonance imaging method for creating the T1 map, for example, there is MOLLI (modified Look-Locker Inversion Recovery) method.
However, MOLLI method is susceptible to factors such as a heart rate. Therefore, if a heart rate changes, the accuracy of a measured T1 value may decrease.
A magnetic resonance imaging apparatus according to an embodiment includes processing circuitry and sequence control circuitry. The processing circuitry sets a pattern based on information on heartbeats or pulsebeats of a subject, the pattern being an imaging condition of a pulse sequence for collecting data at a plurality of timings along a relaxation curve of longitudinal magnetization in synchronization with heartbeats or pulsebeats and the pattern defining a relation between heartbeats or pulsebeats, an inversion pulse, and a data collection timing. The sequence control circuitry controls execution of the pulse sequence according to the pattern.
A magnetic resonance imaging apparatus according to embodiments will be explained below in detail with reference to the accompanying drawings.
A static magnetic field magnet 1 is formed in a hollow cylindrical shape and generates a uniform static magnetic field in a space thereof. The static magnetic field magnet 1 is, for example, a permanent magnet or a superconductive magnet. A gradient magnetic field coil 2 is formed in a hollow cylindrical shape and generates a gradient magnetic field in a space thereof.
Specifically, the gradient magnetic field coil 2 is positioned inside of the static magnetic field magnet 1 and generates a gradient magnetic field upon reception of supply of a gradient magnetic field pulse from a gradient magnetic field power supply 3. The gradient magnetic field power supply 3 supplies a gradient magnetic field pulse to the gradient magnetic field coil 2 according to a control signal transmitted from sequence control circuitry 10.
A bed 4 includes a top panel 4a on which the subject P is placed, and the top panel 4a is inserted into the cavity of the gradient magnetic field coil 2 as an imaging port, in a state where the subject P is placed thereon. Generally, the bed 4 is installed so that the longitudinal direction becomes parallel to the central axis of the static magnetic field magnet 1.
Bed control circuitry 5 drives the bed 4 to move the top panel 4a in the longitudinal direction and the vertical direction.
A transmitter coil 6 generates a magnetic field. Specifically, the transmitter coil 6 is positioned inside of the gradient magnetic field coil 2 and generates a magnetic field upon reception of supply of an RF (Radio Frequency) pulse from transmitter circuitry 7. The transmitter circuitry 7 supplies an RF pulse corresponding to a Larmor frequency to the transmitter coil 6, according to a control signal transmitted from the sequence control circuitry 10.
A receiver coil 8 receives a magnetic resonance (hereinafter, MR) signal. Specifically, the receiver coil 8 is positioned inside of the gradient magnetic field coil 2 and receives a magnetic resonance signal emitted from the subject P due to an influence of a magnetic field. The receiver coil 8 also outputs the received magnetic resonance signal to receiver circuitry 9.
The receiver circuitry 9 generates magnetic resonance signal data based on the magnetic resonance signal output from the receiver coil 8, according to a control signal transmitted from the sequence control circuitry 10. Specifically, the receiver circuitry 9 generates magnetic resonance signal data by converting the magnetic resonance signal output from the receiver coil 8 into a digital signal, and transmits the generated magnetic resonance signal data to an image processing apparatus 200 through the sequence control circuitry 10. The receiver circuitry 9 can be provided on a side of a pedestal device including the static magnetic field magnet 1 and the gradient magnetic field coil 2.
The sequence control circuitry 10 controls the gradient magnetic field power supply 3, the transmitter circuitry 7, and the receiver circuitry 9. Specifically, the sequence control circuitry 10 transmits a control signal based on pulse-sequence execution data transmitted from the image processing apparatus 200 to the gradient magnetic field power supply 3, the transmitter circuitry 7, and the receiver circuitry 9. For example, the sequence control circuitry 10 is an integrated circuit such as an ASIC (Application Specific Integrated Circuit) or an FPGA (Field Programmable Gate Array), or an electronic circuit such as a CPU (Central Processing unit) or an MPU (Micro Processing Unit).
The image processing apparatus 200 includes processing circuitry 150, a memory 132, an input interface 134, and a display 135. The processing circuitry 150 has a control function 150a, a generation function 150b, a setting function 150c, a presentation function 150d, a receiver function 150e, and the like.
Respective processing functions performed by the control function 150a, the generation function 150b, the setting function 150c, the presentation function 150d, and the receiver function 150e are stored in the memory 132 in a format of a computer executable program. The processing circuitry 150 is a processor that reads a program from the memory 132 and executes the program to realize a function corresponding to the respective programs. In other words, the processing circuitry 150 in a state where the respective programs have been read has the respective functions illustrated in the processing circuitry 150 in
In other words, there are a case where the respective functions described above are configured as respective programs and one processing circuit executes the respective programs, and a case where a specific function is implemented in a dedicated independent program execution circuit. The control function 150a, the generation function 150b, the setting function 150c, the presentation function 150d, and the receiver function 150e provided in the processing circuitry 150 are respectively an example of a control unit, a generation unit, a setting unit, a presentation unit, and a receiver unit. Further, the sequence control circuitry 10 is an example of a sequence control unit.
The term “processor” used in the above descriptions means, for example, a CPU (Central Processing unit), a GPU (Graphical Processing Unit), or a circuit such as an application specific integrated circuit (ASIC), a programmable logic device (for example, a simple programmable logic device (SPLD), a complex programmable logic device (CPLD), and a field programmable gate array (FPGA). The processor reads a program stored in the memory 132 and executes the program to realize the functions thereof. Instead of storing the program in the memory 132, it can be configured to install the program directly in the circuit of the processor. In this case, the processor reads and executes the program installed in the circuit to realize the functions. The memory 132 is, for example, a semiconductor memory element such as a RAM (Random Access Memory) or a flash memory, a hard disk, or an optical disk.
The memory 132 stores therein image data stored by the generation function 150b, and other pieces of data to be used in the magnetic resonance imaging apparatus 100. The memory 132 is configured by, for example, a semiconductor memory element such as a RAM (Random Access Memory) or a flash memory, a hard disk, or an optical disk.
The input interface 134 receives inputs of various instructions and pieces of information from an operator. The input interface 134 is, for example, a pointing device such as a mouse or a trackball, or an input device such as a keyboard.
The display 135 displays thereon various pieces of information such as image data under control of the processing circuitry 150. The display 135 is, for example, a display device such as a liquid crystal display.
The processing circuitry 150 is connected to the sequence control circuitry 10 by an interface function (not illustrated), and controls input and output of data transmitted and received between the sequence control circuitry 10 and the image processing apparatus 200.
The processing circuitry 150 executes overall control of the magnetic resonance imaging apparatus 100 by the control function 150a, thereby controlling imaging, image generation, and image display. For example, the control function 150a is an integrated circuit such as an ASIC or an FPGA, or an electronic circuit such as a CPU or an MPU.
The processing circuitry 150 reconfigures image data from the magnetic resonance signal data transmitted from the sequence control circuitry 10, and stores the reconfigured image data in the memory 132. The processing circuitry 150 sets imaging conditions of a pulse sequence based on, for example, information on heartbeats or pulsebeats of a subject, or information on the T1 value of an imaging target. The processing performed by the generation function 150b, the setting function 150c, the presentation function 150d, and the receiver function 150e is described later.
A background of the first embodiment is briefly described next.
It is considered that the T1 map displaying the T1 value of a tissue is effective for diagnosis of, for example, diffuse myocardial fibrosis. As the magnetic resonance imaging method for generating the T1 map, for example, there is MOLLI (modified Look-Locker Inversion Recovery) method. In this method, an inversion pulse is applied for multiple times in a predetermined pattern such as 3, 3, 5 described later to perform a data collection for multiple times by changing TI (Inversion Time). In this case, the pattern by which a data collection is performed for multiple times means a pattern defining a relation between heartbeats or pulsebeats, an inversion pulse, and a data collection timing, the pattern being an imaging condition of a pulse sequence to collect pieces of data at a plurality of timings along a relaxation curve of longitudinal magnetization in synchronization with heartbeats or pulsebeats. A flip angle of the inversion pulse to be applied in the first embodiment is not limited to 180 degrees. As an example, the flip angle of the inversion pulse can be an angle from 90 degrees to 180 degrees inclusive, or an angle equal to or larger than 180 degrees. The inversion pulse typically causes longitudinal magnetization of the tissue to be inverted between a positive value and a negative value.
In the upper part of
The lower part of
However, the MOLLI method is susceptible to, for example, a heart rate or a pulse rate. Therefore, if the heart rate or the pulse rate changes, the accuracy of the measured T1 value may decrease, or a breath holding time may become long more than necessary.
For example, if the heart rate or the pulse rate is too low, an application interval of the inversion pulse becomes too long. Therefore, although the longitudinal magnetization is sufficiently relaxed, the next inversion pulse is not applied, thereby generating a waste of time. As a result, the breath holding time increases. Further, for example, the time between the data collection 16a and the data collection 16b increases. As a result, sampling cannot be performed at a time at which a relaxation curve changes most rapidly, and the accuracy of the measured T1 value decreases.
On the other hand, if the heart rate or the pulse rate is too high, the application interval of the inversion pulse becomes too short, and although the longitudinal magnetization is not sufficiently relaxed, the next inversion pulse is applied, so that the accuracy of the measured T1 value is decreased. Further, the longest TI value in which a data collection is performed (for example, the data collection 16e) becomes small. As a result, a data collection cannot be performed sufficiently during the long TI, and the accuracy of the measured T1 value decreases.
Under such a background, the magnetic resonance imaging apparatus 100 according to the first embodiment sets a pattern of a pulse sequence to be applied based on the information on the heartbeats of the subject P, by the setting function 150c provided in the processing circuitry 150. Accordingly, a data collection can be performed efficiently.
The configuration is described with reference to
The flow of the processing performed by the magnetic resonance imaging apparatus 100 is described below with reference to
First, the processing circuitry 150 acquires the heart rate of the subject P (Step S100). For example, the processing circuitry 150 acquires the heart rate of the subject P based on an electric signal acquired through an electrode (not illustrated) attached to the subject P. Subsequently, the processing circuitry 150 compares the heart rate acquired at Step S100 with a predetermined value, to determine which of “high heart rate”, “normal heart rate”, and “low heart rate” the value of the heart rate is (Step S110). For example, if the value of the heart rate is larger than a first value, the processing circuitry 150 determines that “heart rate is high”. If the value of the heart rate does not exceed the first value but is larger than a second value being smaller than the first value, the processing circuitry 150 determines that “heart rate is normal”. If the value of the heart rate does not exceed the second value, the processing circuitry 150 determines that “heart rate is low”. For example, if the value of the heart rate is higher than 80 bmp, the processing circuitry 150 determines that “heart rate is high”. If the value of the heart rate is from 60 bmp to 80 bmp, the processing circuitry 150 determines that “heart rate is normal”. If the value of the heart rate is lower than 60 bmp, the processing circuitry 150 determines that “heart rate is low”.
At Step S110, if the processing circuitry 150 determines that the heart rate of the subject P is “low heart rate”, the processing proceeds to Step S120a, and the processing circuitry 150 sets a pattern corresponding to the low heart rate. At Step S110, if the processing circuitry 150 determines that the heart rate of the subject P is “normal heart rate”, the processing proceeds to Step S120b, and the processing circuitry 150 sets a pattern corresponding to the normal heart rate. At Step S110, if the processing circuitry 150 determines that the heart rate of the subject P is “high heart rate”, the processing proceeds to Step S120c, and the processing circuitry 150 sets a pattern corresponding to the high heart rate.
The “pattern corresponding to the normal heart rate” is a pulse sequence of, for example, the MOLLI method illustrated in
The pattern when the heart rate is low is described first.
In
The pattern in
Further, the pattern in
Further, in the pattern in
Further, in the pattern in
The reason for the processing circuitry 150 performing such setting is as follows.
First, when the heart rate of the subject falls below a predetermined threshold, an R-R interval is increased. In this case, during a dummy cycle for three heartbeats after the first collection has been performed among the pattern of, for example, “3, (3), 3, (3), 5” in
Further, when the breath holding time is maintained the same, the processing circuitry 150 can perform setting to increase the number of applications of the inversion pulses by reducing the time interval between the inversion pulses.
That is, as a result of increase in the number of applications of the inversion pulses, the measurement accuracy of the T1 value is improved.
Secondly, when the heart rate of the subject falls below a predetermined threshold, the R-R interval is increased. However, as a result, the time interval of the TI time between the collected data points also increases. For example, in
Under such a background, the processing circuitry 150 performs setting to perform the data collection 18a newly, in order to suppress the influence of the increase of the time interval between the data collection 16a and the data collection 14b in
Next, a pattern when a heart rate is high is described with reference to
In
In this case, the pattern in
Further, the pattern in
Further, in the pattern in
In the pattern in
The reason for the processing circuitry 150 performing such setting is as follows.
First, if the heart rate of the subject exceeds a predetermined threshold, the R-R interval is shortened. In this case, there is an instance where longitudinal magnetization is completely recovered during a dummy cycle for three heartbeats after the first collection has been performed, among the pattern of, for example, “3, (3), 3, (3), 5” in
Secondly, if the heart rate of the subject exceeds a predetermined threshold, the R-R interval is shortened. However, as a result, the collected data points concentrate on a portion having a small TI and, on the contrary, the number of data points having a large TI value decreases. Accordingly, a decrease in the number of data points in a portion having a large TI value causes a decrease at the accuracy of curve fitting of T1 calculation.
Under such a background, the processing circuitry 150 can collect data at the data points having a small TI value and the data points having a large TI value with good balance by increasing the number of collections per one inversion pulse, and can maintain the accuracy of curve fitting. In this manner, by performing any of the processes at Steps S120a to S120c, the processing circuitry 150 applies the inversion pulse at a plurality of first times by the setting function 150c, and sets the imaging conditions of the pulse sequence for collecting data at a plurality of second times in electrocardiographic synchronization, based on the information on the heartbeats or pulsebeats of the subject P. In other words, the processing circuitry 150 sets by the setting function 150c a pattern based on the information on the heartbeats or pulsebeats of the subject, the pattern being
the imaging condition of the pulse sequence for collecting data at a plurality of timings along the relaxation curve of longitudinal magnetization in synchronization with the heartbeats or pulsebeats and the pattern defining a relation between the heartbeats or pulsebeats, the inversion pulse, and the data collection timing. Further, the sequence control circuitry 10 controls execution of the pulse sequence according to the pattern.
As an example of the pulse sequence, for example, the pulse sequence of the MOLLI method can be mentioned. In this example, “to set the imaging conditions” means, for example, to set the plurality of first times and the plurality of second times. The first times are, for example, times corresponding to the inversion pulses 10a, 10b, 10c, and 10d in
Subsequently, the processing circuitry 150 transmits the imaging conditions set at any of Steps S120a to S120c to the sequence control circuitry 10. The sequence control circuitry 10 having received the imaging conditions set by the processing circuitry 150 executes the pulse sequence by using the received imaging conditions (Step S130). The processing circuitry 150 acquires data related to the plurality of TIs based on the pulse sequence executed by the sequence control circuitry 10. The processing circuitry 150 performs curve fitting and other processing to the acquired data related to the plurality of TIs to generate the T1 map by the generation function 150b (Step S140). The processing circuitry 150 causes the display 135 to display the generated T1 map by the control function 150a. The display 135 displays the generated T1 map (Step S150).
In the first embodiment, the processing circuitry 150 sets the pattern of the pulse sequence based on the information on the heartbeats or pulsebeats of the subject P by the setting function 150c. Accordingly, the magnetic resonance imaging apparatus 100 can efficiently perform a data collection for generating the T1 map.
In the first embodiment, there has been described a case where the processing circuitry 150 sets imaging conditions of a pulse sequence (performs pattern setting of a pulse sequence) based on information on the heartbeats or pulsebeats of the subject P. In the second embodiment, the processing circuitry 150 sets the imaging conditions of a pulse sequence based on information on the T1 value of an imaging target.
Specifically, when the T1 value of the imaging target is small, the imaging target is magnetically relaxed in a short time. Accordingly, the processing circuitry 150 sets a pulse sequence of the pattern similar to a pattern when the heart rate is relatively small described in the first embodiment (for example, the pulse sequence illustrated in
On the other hand, when the T1 value of the imaging target is large, it takes a long time for the imaging target to magnetically relax. Accordingly, the processing circuitry 150 sets the pulse sequence similar to the case having a relatively large heart rate described in the first embodiment (for example, the pulse sequence illustrated in
In this manner, the processing circuitry 150 sets the pattern of the pulse sequence corresponding to the T1 value of the imaging target, thereby enabling to collect pieces of data efficiently for creating the T1 map.
The processing performed by the magnetic resonance imaging apparatus 100 according to the second embodiment is described with reference to
The processing circuitry 150 first receives an input of information on the T1 value of an imaging target, for example, information on the presence or absence of a contrast agent, information on a body part to be imaged, and the T1 value from a user by the receiver function 150e, for example, through the display 135 (Step S200). Because the T1 value of the imaging target largely changes due to, for example, the presence or absence of the contrast agent, the information on the presence or absence of the contrast agent is information on the T1 value of the imaging target. Because the T1 value of the imaging target largely changes according to the body part to be imaged and a body part to be focused (for example, whether to focus on only a myocardium or focus on both the myocardium and blood), these pieces of information are information on the T1 value of the imaging target.
A display area 31 is a user interface in which the display 135 receives an input of the information on the presence or absence of the contrast agent from the user. In the display area 31, buttons 32a and 32b are buttons for the display 135 to receive an input indicating that the imaging target is “before input of contrast agent” and “after input of contrast agent” respectively from the user.
A display area 33 is a user interface in which the display 135 receives the information on the body part to be imaged from the user. Buttons 34a and 34b are buttons for the display 135 to receive an input indicating that the body part to be imaged is “only myocardium” or “both myocardium and blood” respectively from the user.
An input field 35 is for the display 135 to receive an input of the T1 value from a user. An OK button 36 is a button for confirming an input result from a user.
At Step S200, when a user selects the OK button 36 after selecting the button 32a, the display 135 receives an input indicating that the imaging target is “before input of contrast agent”. When the user selects the OK button 36 after selecting the button 32b, the display 135 receives an input indicating that the imaging target is “after input of contrast agent”. When the user selects the OK button 36 after selecting the button 34a, the display 135 receives an input indicating that the body part to be imaged is “only myocardium”. When the user selects the OK button 36 after selecting the button 34b, the display 135 receives an input indicating that the body part to be imaged is “both myocardium and blood”. When the user selects the OK button 36 after an input of the T1 value into the input field 35, the display 135 receives the input T1 value.
Subsequently, the processing circuitry 150 determines what kind of input the display 135 has received at Step S200 (Step S201).
When the display 135 receives an input indicating that the imaging target is “before input of contrast agent” through the button 32a at Step S200, the process proceeds to Step S202a, and the processing circuitry 150 sets the pattern of the pulse sequence corresponding to “before input of contrast agent” by the setting function 150c. When the display 135 receives an input indicating that the imaging target is “after input of contrast agent” through the button 32b at Step S200, the process proceeds to Step S202b, and the processing circuitry 150 sets the pattern of the pulse sequence corresponding to “after input of contrast agent” by the setting function 150c. When the display 135 receives an input of the T1 value of the imaging target through the input field 35 at Step S200, the process proceeds to Step S202c, and the processing circuitry 150 sets the pattern of the pulse sequence corresponding to the manually input T1 value by the setting function 150c at Step S200. If there is no particular input at Step S200, the process proceeds to Step S202d, and the processing circuitry 150 sets the pattern of the standard pulse sequence by the setting function 150c.
The patterns of the pulse sequence set by the processing circuitry 150 at Steps S202a to 202d are described.
At any of Steps S202a to 202d, the processing circuitry 150 first calculates the T1 value of the imaging target based on the input received from a user at Step S200.
For example, in the case of Step S202a, the processing circuitry 150 calculates the T1 value of the imaging target before an input of a contrast agent, while referring to an input item regarding the body part to be imaged. For example, when the body part to be imaged input at Step S200 is “only myocardium”, the processing circuitry 150 acquires information indicating that the body part to be imaged is “only myocardium” and the T1 value of the imaging target “before input of contrast agent” from a predetermined table, and calculates the acquired value as the T1 value. For example, when the body part to be imaged input at Step S200 is “myocardium and blood”, the processing circuitry 150 acquires information indicating that the body part to be imaged is “myocardium and blood” and the T1 value of the imaging target “before input of contrast agent” (for example, an average value of T1 before input of contrast agent) from the predetermined table, and calculates the acquired value as the T1 value. The same applies to Step S202b.
In the case of Step S202c, for example, if the T1 value manually input at Step S200 is not an abnormal value, the processing circuitry 150 calculates the input T1 value as the T1 value, and if the input T1 value is an abnormal value, the processing circuitry 150 prompts the user to re-input the value, and calculates the input value as the T1 value. In the case of Step S202d, the processing circuitry 150 calculates a default value as the T1 value.
Subsequently, when the T1 value of the imaging target is calculated, the processing circuitry 150 sets the pattern of the pulse sequence to be performed at the subsequent stages based on the calculated T1 value of the imaging target by the setting function 150c at the respective Step S202a to Step S202d.
As described above, if the T1 value of the imaging target is small, the processing circuitry 150 sets the pulse sequence having the same pattern as the case where the heart rate is relatively low as illustrated in
In other words, if the T1 value of the imaging target falls below a predetermined threshold, the processing circuitry 150 performs setting by the setting function 150c so that the time interval between inversion pulses to be applied becomes smaller (the number of heartbeats or pulsebeats between inversion pulses becomes smaller), as compared to the case where the T1 value of the imaging target does not fall below the predetermined threshold. In this case, for example, the processing circuitry 150 sets the pulse sequence of the pattern as illustrated in
As an example, the processing circuitry 150 performs setting by the setting function 150c so that the number of applications of inversion pulses increases in one repetition period. For example, the processing circuitry 150 performs setting to add a new inversion pulse and increase the number of pieces of collected data. As another example, the processing circuitry 150 performs setting so that the number of data collections decreases per one inversion pulse. As another example, the processing circuitry 150 performs setting to decrease the number of applications of dummy pulses. As still another example, the processing circuitry 150 can perform setting to decrease the breath holding time.
When the T1 value of the imaging target exceeds a predetermined threshold, the processing circuitry 150 performs setting by the setting function 150c so that the number of data collections per one inversion pulse becomes larger (the number of heartbeats or pulsebeats becomes larger), as compared to the case where the T1 value of the imaging target does not exceed the predetermined threshold. In this case, for example, the processing circuitry 150 sets the pulse sequence of the pattern as illustrated in
As an example, the processing circuitry 150 performs setting by the setting function 150c so that the time interval between inversion pulses to be applied increases. As another example, the processing circuitry 150 performs setting so that the number of applications of the inversion pulses decreases in one repetition period. As still another example, the processing circuitry 150 can perform setting so that the breath holding time becomes short.
The case where the processing circuitry 150 performs setting corresponding to the relative relation between the T1 value and the heart rate has been described. However, the present embodiment is not limited thereto. As the T1 value decreases, the accuracy may not become sufficient at the data point where the TI is the lowest. Accordingly, when the T1 value is lower than a reference threshold, the processing circuitry 150 can set the initial TI value (for example, the TI value corresponding to the data collection 11a in
In this manner, the processing circuitry 150 sets the imaging conditions by the setting function 150c based on the information with respect to the T1 value of the imaging target received by the receiver function 150e. In other words, the processing circuitry 150 sets by the setting function 150c a pattern defining the relation between the heartbeats or pulsebeats, the inversion pulse, and the data collection timing, which is the imaging condition of the pulse sequence for collecting data at a plurality of timings along the relaxation curve of longitudinal magnetization in synchronization with the heartbeats or pulsebeats, based on the information on the heartbeats or pulsebeats of the subject.
By performing any of the processes at Steps S202a to S202d, when the processing circuitry 150 sets the pattern of the pulse sequence by the setting function 150c, the processing circuitry 150 causes the display 135 to display the pattern set at any of Steps S202a to S202d by the control function 150a.
In
Meanwhile, the patterns of the pulse sequence being currently set are coordinated based on the application time of respective inversion pulses as an origin, and displayed in a panel 60 together with various control buttons. The patterns of the pulse sequence being currently set are combined together based on the application time of the respective inversion pulses as an origin, and displayed in one diagram in a panel 61. Display areas 62a, 62b, 62c, 62d, and 62e display TI corresponding to respective data collections. For example, in an example illustrated in
Display areas 64a, 64b, 64c, and 64d display the patterns of the pulse sequence displayed in the panel 61. In the example in
Buttons 65a, 65b, 64e, and 67 are for changing the sampling pattern. For example, when the user clicks the button 65a or 65b, the sampling pattern becomes “5-3-3-1” or “3-3-3-1” respectively. The number of TI groups in which sampling is performed can be also changed. For example, when the user clicks the button 64e or 67, the sampling pattern becomes “4-3-3-1-1” or “4-3-3” respectively.
Buttons 72a, 72b, and 72c are respectively used by the user to save, load, and reset the setting.
Referring back to
Subsequently, the processing circuitry 150 receives an input of a change of the data collection pattern through the display 135 from a user who has referred to the panel 60 or 61 on the display 135 by the receiver function 150e (Step S220). As an example of receiving an input of the change from the user on the panel 60, for example, the processing circuitry 150 receives an input of the change of the data collection pattern through the buttons 53a, 53b, 53c, and 53d by the receiver function 150e. For example, in the example in
As an example of receiving an input of the change on the panel 61 from the user, the processing circuitry 150 receives an input of a change of the data collection pattern through, for example, the buttons 65a, 65b, 64e, and 67 by the receiver function 150e. For example, when the user respectively selects the buttons 65a, 65b, 64e, and 67, the processing circuitry 150 receives an input indicating that the pattern of the pulse sequence is changed from “4-3-3-1” to “5-3-3-1”, “3-3-3-1”, “4-3-3-1-1” and “4-3-3” respectively from the user by the receiver function 150e. The processing circuitry 150 receives the TI (for example, the initial TI) of respective data collections through, for example, the button 63a or 63b by the receiver function 150e. The processing circuitry 150 appropriately displays the change performed on the panel 60 by reflecting and linking the change also on and with the panel 50 by the receiver function 150e.
Subsequently, the processing circuitry 150 determines whether an input of a change of the pattern of the pulse sequence has been received through the display 135 (Step S230). If the processing circuitry 150 determines that an input of the change of the pattern of the pulse sequence has been received (YES at Step S230), the processing circuitry 150 having the setting function 150c corrects the pattern of the pulse sequence based on the input received by the receiver function 150e at Step S220 to set the imaging conditions (Step S270). Thereafter, the process returns to Step S210.
On the other hand, if the processing circuitry 150 has not received an input of the change of the pattern of the pulse sequence (NO at Step S230), because there is no particular change in the pattern of the pulse sequence, the sequence control circuitry 10 that has received the imaging conditions set by the processing circuitry 150 executes the pulse sequence by using the received imaging conditions (Step S240). The processing circuitry 150 acquires the data related to a plurality of TIs based on the pulse sequence executed by the sequence control circuitry 10 at Step S240. The processing circuitry 150 performs, by the generation function 150b, curve fitting and other processing with respect to the data related to the acquired TIs to generate the T1 map (Step S250). The processing circuitry 150 causes the display 135 to display the generated T1 map by the control function 150a. The display 135 displays the generated T1 map (Step S260).
In the second embodiment, the processing circuitry 150 sets the pattern of a pulse sequence based on the information on the T1 value of the imaging target by the setting function 150c. Accordingly, the magnetic resonance imaging apparatus 100 can efficiently perform a data collection for generating the T1 map.
In the first embodiment, there has been described a case where the pattern of a pulse sequence is set based on information on the heartbeats or pulsebeats of the subject P.
In the second embodiment, there has been described a case where the pattern of a pulse sequence is set based on information on the T1 value of an imaging target. The embodiment is not limited thereto. The processing circuitry 150 can set the imaging conditions based on the information on the heartbeats or pulsebeats of the subject P and the information on the T1 value of the imaging target by the setting function 150c.
Subsequently, the processing circuitry 150 determines whether the heart rate acquired at Step S300 is “high” or “low”, and the T1 value of the imaging target acquired at Step S300 is “large” or “small” (Step S310). For example, if the value of the heart rate exceeds a certain value, the processing circuitry 150 determines that the heart rate is “high”, and if the value of the heart rate does not exceed the certain value, the processing circuitry 150 determines that the heart rate is “low”. Further, if the T1 value exceeds a certain value, the processing circuitry 150 determines that the T1 value is “large”, and if the T1 value does not exceed the certain value, the processing circuitry 150 determines that the T1 value is “small”.
If the processing circuitry 150 determines that the heart rate is “high” and the T1 value is “large” at Step S310, the process proceeds to Step S320a, and the processing circuitry 150 sets a pattern corresponding to the “high” heart rate and the “large” T1 value. If the processing circuitry 150 determines that the heart rate is “high” and the T1 value is “small” at Step S310, the process proceeds to Step S320b, and the processing circuitry 150 sets a pattern corresponding to the “high” heart rate and the “small” T1 value. If the processing circuitry 150 determines that the heart rate is “low” and the T1 value is “large” at Step S310, the process proceeds to Step S320c, and the processing circuitry 150 sets a pattern corresponding to the “low” heart rate and the “large” T1 value. If the processing circuitry 150 determines that the heart rate is “low” and the T1 value is “small” at Step S310, the process proceeds to Step S320d, and the processing circuitry 150 sets a pattern corresponding to the “low” heart rate and the “small” T1 value.
As described in the first embodiment, when the heart rate is “low”, it is desired to decrease the application interval of the inversion pulse, to decrease the number of data collections per one inversion pulse, and to increase the number of applications of the inversion pulses (the number of times of LL (Looker-Locker) experiments) in one repetition period. On the contrary, when the heart rate is “high”, it is desired to increase the application interval of the inversion pulse, to increase the number of data collections per one inversion pulse, and to decrease the number of applications of the inversion pulses (the number of times of LL (Looker-Locker) experiments) in one repetition period.
Further, as described in the second embodiment, when the T1 value is “small”, it is desired to decrease the application interval of the inversion pulse, to decrease the number of data collections per one inversion pulse, and to increase the number of applications of the inversion pulses (the number of times of LL (Looker-Locker) experiments) in one repetition period. On the contrary, when the T1 value is “large”, it is desired to increase the application interval of the inversion pulse, to increase the number of data collections per one inversion pulse, and to decrease the number of applications of the inversion pulses (the number of times of LL (Looker-Locker) experiments) in one repetition period.
Accordingly, when the heart rate is “low” and the T1 value is “small”, it is desired to decrease the application interval of the inversion pulse, to decrease the number of data collections per one inversion pulse, and to increase the number of applications of the inversion pulses (the number of times of LL (Looker-Locker) experiments) in one repetition period. On the contrary, when the heart rate is “high” and the T1 value is “large”, it is desired to increase the application interval of the inversion pulse, to increase the number of data collections per one inversion pulse, and to decrease the number of applications of the inversion pulses (the number of times of LL (Looker-Locker) experiments) in one repetition period.
Accordingly, in the case at Step S320d (the heart rate is “low” and the T1 value is “small”), the processing circuitry 150 performs setting by the setting function 150c to decrease the application interval of the inversion pulse, to decrease the number of data collections per one inversion pulse, and to increase the number of applications of the inversion pulses in one repetition period.
In the case at Step S320a (the heart rate is “high” and the T1 value is “large”), the processing circuitry 150 performs setting by the setting function 150c to increase the application interval of the inversion pulse, to increase the number of data collections per one inversion pulse, and to decrease the number of applications of the inversion pulses in one repetition period.
Regarding the cases at Step S320b and Step S320c, the processing circuitry 150 performs setting, for example, to be intermediate between Step S320d and Step S320a.
Next, the case at Step S320b (the heart rate is “high” and the T1 value is “small”) is described. In this case, because the T1 value is small, there is no data point at which the TI in curve fitting is small, thereby causing an estimation error in the T1 value. Therefore, in addition to the setting described above, the processing circuitry 150 sets the initial TI and performs setting so that data points having a small TI are collected sufficiently. The initial TI is illustrated in
Here, the description returns to the case at Step S320d (the heart rate is “low” and the T1 value is “small”). In this case, as in the case at Step S320b, there is no data point at which the TI is small, an estimation error occurs in the T1 value. Therefore, the processing circuitry 150 performs setting of, for example, the initial TI. In addition, as described above, the processing circuitry 150 performs setting to decrease the application interval of the inversion pulse, for example, by decreasing the number of dummy cycles, and conversely to increase the number of applications of the inversion pulses in one repetition period.
Typically, the processing circuitry 150 sets up the pattern of the pulse sequence to (3, (1), 3, (1), 3, (1), 2”, and sets a set of the initial TIs, for example, to 50 milliseconds, 100 milliseconds, 300 milliseconds, and 500 milliseconds.
Further, when the T1 value is large, as described in the second embodiment, longitudinal magnetization may not be sufficiently relaxed before the next inversion pulse is applied, and the data point at which the TI becomes the longest may not have a sufficiently large value. Therefore, in the case at Step S320a (the heart rate is “high” and the T1 value is “large”) and the case at Step S320c (the heart rate is “low” and the T1 value is “large”), the processing circuitry 150 performs setting by the setting function 150c to increase the application interval of the inversion pulse, to increase the number of data collections per one inversion pulse, and to decrease the number of applications of the inversion pulses in one repetition period.
In the case at Step S320c, as compared to the case at Step S320a, the phenomenon that the longitudinal magnetization is not sufficiently relaxed does not easily occur. Therefore, in the case at Step S320c, as compared to the case at Step S320a, the processing circuitry 150 may not increase the application interval of the inversion pulse so much.
Subsequently, the processing circuitry 150 transmits the imaging conditions set at any of Steps S320a to S320d to the sequence control circuitry 10. The sequence control circuitry 10 having received the imaging conditions set by the processing circuitry 150 executes the pulse sequence by using the received imaging conditions (Step S330). The processing circuitry 150 acquires data related to the plurality of TIs based on the pulse sequence executed by the sequence control circuitry 10 at Step S330. The processing circuitry 150 generates the T1 map by the generation function 150b by performing curve fitting and other processing with respect to the acquired data related to the TIs (Step S340). The processing circuitry 150 causes the display 135 to display the generated T1 map by the control function 150a. The display 135 displays the generated T1 map (Step S350).
In this manner, in the third embodiment, the processing circuitry 150 sets the pattern of the pulse sequence based on both the values of the heart rate and the T1 value of the imaging target. Accordingly, the magnetic resonance imaging apparatus according to the third embodiment can set more appropriate pulse sequence according to the subject P and an imaging object.
Embodiments are not limited to the above examples. In the first to third embodiments, there has been described a case where the processing circuitry 150 sets the number of heartbeats or pulsebeats between inversion pulses by the setting function 150c based on the information on the heartbeats or pulsebeats, to set the pattern defining a relation between the heartbeats or pulsebeats, the inversion pulse, and the data collection timing. The embodiment is not limited thereto.
For example, the processing circuitry 150 can set a pattern defining a relation between the heartbeats or pulsebeats, the inversion pulse, and the data collection timing by setting a time during which a data collection is continuously performed after an application of the inversion pulse by the setting function 150c based on the information on the heartbeats or pulsebeats.
In the embodiments described above, the sequence control circuitry 10 performs a data collection for a predetermined number of times at a predetermined timing based on the heartbeats of a subject, for example, as in the pattern “3, (3), 3, (3), 5”. In a fourth embodiment, the sequence control circuitry 10 performs a data collection continuously for a predetermined time after an application of the inversion pulse. For example, if the time during which a data collection is continuously performed is three seconds after an application of the inversion pulse, the sequence control circuitry 10 continuously performs a data collection until three seconds has passed after an application of the inversion pulse, for each heartbeat. As an example, the sequence control circuitry 10 performs a data collection three times at a time point of 0.5 second, 1.5 seconds, and 2.5 seconds after an application of the inversion pulse. In this case, for example, if the heart rate of the subject increases, a data collection performed by the sequence control circuitry 10 is four times. Further, if the heart rate of the subject decreases, a data collection performed by the sequence control circuitry 10 is two times.
In this manner, when a time during which a data collection is continuously performed after an application of an inversion pulse is fixed, if the heart rate of the subject increases, the data collection interval becomes short, and thus the number of data collections increases. As a result, if the heart rate of the subject increases, the sequence control circuitry 10 may perform data collections for the number of times more than the required number of data collections, thereby increasing the total imaging time. On the contrary, if the heart rate of the subject decreases, the data collection interval becomes long, thereby decreasing the number of data collections. As a result, if the heart rate of the subject decreases, the number of data collections may not be sufficient.
Under such a background, in the fourth embodiment, the processing circuitry 150 sets a time during which a data collection is continuously performed after an application of an inversion pulse by the setting function 150c based on the information on the heartbeats or the pulsebeats. For example, if the heart rate or the pulse rate of a subject exceeds a predetermined threshold, the processing circuitry 150 sets the time during which a data collection is continuously performed after an application of the inversion pulse by the setting function 150c, so that the time during which a data collection is continuously performed after an application of the inversion pulse becomes shorter than a case where the heart rate or the pulse rate of the subject does not exceed the predetermined threshold. For example, if the heart rate of the subject is equal to or higher than the predetermined threshold, the processing circuitry 150 sets the time during which a data collection is continuously performed after an application of the inversion pulse to four seconds by the setting function 150c, and if the heart rate of the subject is lower than the predetermined threshold, the processing circuitry 150 sets the time during which a data collection is continuously performed after an application of the inversion pulse to five seconds by the setting function 150c. Further, for example, if the heart rate or the pulse rate of the subject falls below the predetermined threshold, the processing circuitry 150 sets, by the setting function 150c, the time during which a data collection is continuously performed after an application of the inversion pulse so that the time during which a data collection is continuously performed after an application of the inversion pulse becomes longer than a case where the heart rate or the pulse rate of the subject does not fall below the predetermined threshold.
Accordingly, in the magnetic resonance imaging apparatus 100 according to the fourth embodiment, the sequence control circuitry 10 can perform imaging with necessary and sufficient imaging time and the number of times of imaging, according to the heart rate (or the pulse rate) of the subject, without increasing the total imaging time and avoiding a case where the number of data collections is not sufficient.
In a fifth embodiment, there is described a case where the processing circuitry 150 collects information on heartbeats or pulsebeats by the control function 150a on a real time basis during execution of a pulse sequence to dynamically change a pattern defining a relation between the heartbeats or pulsebeats, the inversion pulse, and the data collection timing, based on the information collected during execution of the pulse sequence, and the sequence control circuitry 10 executes the pulse sequence based on the changed pattern.
As an example, the processing circuitry 150 dynamically sets the time during which a data collection is performed after an application of an inversion pulse, by the setting function 150c based on the information on the heartbeats or the pulsebeats. For example, if the heart rate or the pulse rate of a subject exceeds a predetermined threshold, the processing circuitry 150 sets the time during which a data collection is performed after an application of the inversion pulse by the setting function 150c, so that the time during which a data collection is performed after an application of the inversion pulse becomes shorter than a case where the heart rate or the pulse rate of the subject does not exceed the predetermined threshold. For example, if the heart rate of the subject is equal to or higher than the predetermined threshold, and when an inversion pulse is applied next, the processing circuitry 150 sets the time during which a data collection is performed after an application of the inversion pulse to four seconds by the setting function 150c, and if the heart rate of the subject is lower than the predetermined threshold, and when an inversion pulse is applied next, the processing circuitry 150 sets the time during which a data collection is performed after an application of the inversion pulse to five seconds by the setting function 150c.
In this manner, the processing circuitry 150 dynamically changes the data collection pattern by the setting function 150c according to the heart rate or the like of the subject. The sequence control circuitry 10 executes the pulse sequence based on the changed pattern. Accordingly, in the magnetic resonance imaging apparatus 100 according to the fifth embodiment, the sequence control circuitry 10 can execute a pulse sequence having been flexibly optimized due to the change of the heart rate or the like of the subject.
As another example, the processing circuitry 150 dynamically changes the pattern defining the relation between the heartbeats or pulsebeats, the inversion pulse, and the data collection timing by the setting function 150c by dynamically changing the heart rate or the like, for example, in a waiting time, based on the information on the heartbeats or the pulsebeats. For example, if a state in which the heart rate of the subject is equal to or higher than a predetermined threshold is maintained, the processing circuitry 150 sets the pattern of the pulse sequence to be executed to “3, (3), 3, (3), 5” by the setting function 150c. Further, if the heart rate of the subject has changed to be less than the predetermined threshold, it is decided that the waiting time for collection can be made short. Therefore, the processing circuitry 150 dynamically changes the pattern of the pulse sequence to be executed to “3, (2), 3, (3), 5” by the setting function 150c. The sequence control circuitry 10 performs an application of the inversion pulse and data collection at a timing according to the changed pattern of the pulse sequence. Accordingly, reduction of the imaging time can be realized by decreasing, for example, an unnecessary waiting time, and an imaging failure caused because the time from an application of an inversion pulse to data collection is too short can be prevented.
The processing circuitry 150 can dynamically change the pattern defining the relation between the heartbeats or pulsebeats, the inversion pulse, and the data collection timing, by the setting function 150c, for example, based on information on abnormal cardiac rhythm. As an example, upon detection of abnormal cardiac rhythm by the setting function 150c, the processing circuitry 150 decides that the data of that portion needs to be collected again, and transmits a signal indicating this matter to the sequence control circuitry 10. The sequence control circuitry 10 having received the notification of detection of abnormal cardiac rhythm extends the period for performing the data collection, for example, by one more heartbeat to perform the data collection.
As described above, according to the magnetic resonance imaging apparatus 100 of the fifth embodiment, a pulse sequence having been flexibly optimized with respect to a change of the heart rate or the pulse rate of the subject can be executed.
In the first to fifth embodiments, there has been described a case where the processing circuitry 150 generates the T1 map by the generation function 150b. However, the embodiment is not limited thereto. The processing circuitry 150 can generate an ECV (Extracellular Volume fraction) map. The ECV map represents an extracellular volume of, for example, cardiac muscle, and a value thereof increases, for example, in the case of diffuse myocardial fibrosis. The ECV map of the cardiac muscle can be generated based on values of T1 of the cardiac muscle before an input of a contrast agent, T1 of the cardiac muscle after an input of the contrast agent, T1 of the blood before an input of the contrast agent, and T1 of the blood after an input of the contrast agent.
The processing circuitry 150 sets the pattern of the pulse sequence corresponding to “before input of contrast agent”, for example, by performing the process at Step S202a described with reference to
Subsequently, the processing circuitry 150 sets the pattern of the pulse sequence corresponding to “after input of contrast agent”, for example, by performing the process at Step S202b described with reference to
At Step S460, the processing circuitry 150 generates the ECV map by the generation function 150b based on the first data and the second data (Step S460). The processing circuitry 150 causes the display 135 to display the ECV map generated at Step S460 (Step S470).
In the present embodiment, a case where the ECV map is generated in the second embodiment has been described; however, the embodiment is not limited thereto. For example, the ECV map can be generated, for example, in the first and third embodiments. Further, a case where the input of information on the T1 value is received manually in the second embodiment has been described; however, the embodiment is not limited thereto. The magnetic resonance imaging apparatus 100 can acquire the value of the T1 value automatically, to set the appropriate pattern of the pulse sequence, for example, adaptively.
Embodiments are not limited to those described above. For example, the GUI described in the second embodiment, such as the GUI illustrated in
Program
The instructions shown in the process procedures described in the above embodiments can be executed based on a program as software. As a general-purpose computer system stores the program therein in advance and reads the program, it is possible to obtain effects identical to those realized by the magnetic resonance imaging apparatus 100 and the image processing apparatus 200 described in the above embodiments. The instructions described in the above embodiments are stored, as a program that can be executed by a computer, in a recording medium such as a magnetic disk (such as a flexible disk or a hard disk), an optical disk (such as a CD-ROM, a CD-R, a CD-RW, a DVD-ROM, a DVDiR, a DVD±RW), a semiconductor memory, or other types of recording media in the same category. As far as the computer or an incorporating system thereof is a readable storage medium, its storage format can be of any type. As the computer reads the program from the storage medium and executes instructions described in the program based on the program on a CPU, it is possible to realize operations identical to those of the magnetic resonance imaging apparatus and the image processing apparatus described in the above embodiments. It is needles to mention that, when the computer acquires or reads the program, the acquisition or reading can be performed through a network.
Further, it is also possible that a part of the respective processes for realizing the above embodiments can be performed with, for example, an OS (Operating System) being operated on a computer based on instructions from a program installed from a storage medium into the computer or an incorporating system thereof, database management software, or MW (middleware) such as a network.
Furthermore, the type of the storage medium is not limited to a medium independent from a computer or an incorporating system thereof, and the type also includes a storage medium having downloaded and stored therein, or temporarily stored therein, a program transmitted through a LAN (Local Area Network), the Internet, and the like.
Further, the number of the storage medium is not limited to one, and when processes in the embodiments described above are performed by plural media, these media are also included in the storage medium in the above embodiments, and the configuration of such media can be of any type.
The computer or the incorporating system thereof in the above embodiments is used for performing the respective processes in the embodiments described above based on a program stored in a storage medium, and can have any type of configuration such as a device constituted by any one of a personal computer, a microcomputer, and the like, or a system in which a plurality of devices are connected to one another through a network.
Further, the computer in the above embodiment is not limited to a personal computer, and also includes devices such as an arithmetic processing unit and a microcomputer. The computer is a collective term for a device or an apparatus that can realize the functions in the above embodiments with a program.
Hardware Configuration
According to the magnetic resonance imaging apparatus according to at least one of the embodiments described above, a data collection can be performed efficiently.
While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Indeed, the novel embodiments described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the embodiments described herein may be made without departing from the spirit of the inventions. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the inventions.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2016-186191 | Sep 2016 | JP | national |
| 2017-182918 | Sep 2017 | JP | national |
