U.S. patent application number 13/108314 was filed with the patent office on 2011-11-24 for ultrasonic diagnostic apparatus and ultrasonic diagnostic apparatus control method.
This patent application is currently assigned to TOSHIBA MEDICAL SYSTEMS CORPORATION. Invention is credited to Tatsuro BABA, Go TANAKA, Isao UCHIUMI, Cong YAO.
Application Number | 20110288413 13/108314 |
Document ID | / |
Family ID | 44483772 |
Filed Date | 2011-11-24 |
United States Patent
Application |
20110288413 |
Kind Code |
A1 |
BABA; Tatsuro ; et
al. |
November 24, 2011 |
ULTRASONIC DIAGNOSTIC APPARATUS AND ULTRASONIC DIAGNOSTIC APPARATUS
CONTROL METHOD
Abstract
According to one embodiment, an ultrasonic diagnostic apparatus
is configured to execute an imaging mode of alternately executing a
continuous wave Doppler mode of acquiring time-series Doppler data
by performing continuous wave transmission/reception with respect
to an object and a B mode of acquiring tomogram data represented by
luminance by transmitting and receiving a pulse wave to and from
the object, the apparatus includes a data acquisition unit
configured to acquire continuous wave Doppler data and the tomogram
data by alternately executing the continuous wave Doppler mode and
the B mode while switching the modes, and a display unit configured
to simultaneously display Doppler spectrum information generated
based on the continuous wave Doppler data and a tomogram generated
based on the tomogram data.
Inventors: |
BABA; Tatsuro; (Otawara-shi,
JP) ; YAO; Cong; (Otawara-shi, JP) ; TANAKA;
Go; (Otawara-shi, JP) ; UCHIUMI; Isao;
(Nasushiobara-shi, JP) |
Assignee: |
TOSHIBA MEDICAL SYSTEMS
CORPORATION
OTAWARA-SHI
JP
KABUSHIKI KAISHA TOSHIBA
TOKYO
JP
|
Family ID: |
44483772 |
Appl. No.: |
13/108314 |
Filed: |
May 16, 2011 |
Current U.S.
Class: |
600/441 |
Current CPC
Class: |
G01S 7/52034 20130101;
A61B 8/13 20130101; G01S 7/52066 20130101; G01S 15/8979 20130101;
A61B 8/463 20130101; A61B 8/5246 20130101; A61B 8/06 20130101; G01S
7/52074 20130101 |
Class at
Publication: |
600/441 |
International
Class: |
A61B 8/14 20060101
A61B008/14 |
Foreign Application Data
Date |
Code |
Application Number |
May 19, 2010 |
JP |
2010-115547 |
Claims
1. An ultrasonic diagnostic apparatus which is configured to
execute an imaging mode of alternately executing a continuous wave
Doppler mode of acquiring time-series Doppler data by performing
continuous wave transmission/reception with respect to an object
and a B mode of acquiring tomogram data represented by luminance by
transmitting and receiving a pulse wave to and from the object, the
apparatus comprising: a data acquisition unit configured to acquire
continuous wave Doppler data and the tomogram data by alternately
executing the continuous wave Doppler mode and the B mode while
switching the modes; and a display unit configured to
simultaneously display Doppler spectrum information generated based
on the continuous wave Doppler data and a tomogram generated based
on the tomogram data.
2. The apparatus according to claim 1, further comprising: a
calculation unit configured to calculate a transient response
component generated due to switching between the continuous wave
Doppler mode and the B mode; a subtraction unit configured to
subtract the calculated transient response component from the
continuous wave Doppler data; and a generation unit configured to
generate the Doppler spectrum information by using the continuous
wave Doppler data from which the transient response component is
subtracted.
3. The apparatus according to claim 2, wherein the calculation unit
identifies a system by a parametric model using a biological signal
of the object as an external input, and estimates Doppler data lost
due to switching between the continuous wave Doppler mode and the B
mode by using the identified system, and interpolates the
continuous wave Doppler data by using the estimated Doppler
data.
4. The apparatus according to claim 3, wherein the calculation unit
estimates the lost Doppler data by multiplying a predicted spectrum
from temporal past of the lost Doppler data and a predicted
spectrum from temporal future of the lost Doppler data by a
temporally changing weighting function and adding the spectra.
5. The apparatus according to claim 4, wherein the temporally
changing weighting function is a cosine function.
6. The apparatus according to claim 2, wherein the calculation unit
calculates a transient response component generated at a preceding
stage portion relative to a wall filter of the data acquisition
unit.
7. The apparatus according to claim 2, wherein the calculation unit
calculates a transient response component generated in a wall
filter and frequency analysis unit of the data acquisition
unit.
8. The apparatus according to claim 2, wherein the calculation unit
calculates the transient response component from a spectrum having
a power dimension by executing positive-negative symmetric post
filter processing, and the subtraction unit subtracts the
transmission component after the post filter processing from the
continuous wave Doppler data having a power dimension.
9. The apparatus according to claim 2, wherein the calculation unit
calculates the transient response component as a time axis waveform
by changing a magnitude of the transient response component based
on a preset step response waveform table, and the subtraction unit
subtracts the transient response component as the time axis
waveform from the continuous wave Doppler data of the time axis
waveform.
10. The apparatus according to claim 2, wherein the calculation
unit calculates the transient response component by using an output
from an A/D converter of the data acquisition unit.
11. A control method for an ultrasonic diagnostic apparatus which
is configured to execute an imaging mode of alternately executing a
continuous wave Doppler mode of acquiring time-series Doppler data
by performing continuous wave transmission/reception with respect
to an object and a B mode of acquiring tomogram data represented by
luminance by transmitting and receiving a pulse wave to and from
the object, the method comprising: acquiring continuous wave
Doppler data and the tomogram data by alternately executing the
continuous wave Doppler mode and the B mode while switching the
modes; and simultaneously displaying Doppler spectrum information
generated based on the continuous wave Doppler data and a tomogram
generated based on the tomogram data.
12. The method according to claim 11, further comprising:
calculating a transient response component generated due to
switching between the continuous wave Doppler mode and the B mode;
subtracting the calculated transient response component from the
continuous wave Doppler data; and generating the Doppler spectrum
information by using the continuous wave Doppler data from which
the transient response component is subtracted.
13. The method according to claim 12, wherein calculating comprises
identifying a system by a parametric model using a biological
signal of the object as an external input, and estimating Doppler
data lost due to switching between the continuous wave Doppler mode
and the B mode by using the identified system, and interpolating
the continuous wave Doppler data by using the estimated Doppler
data.
14. The method according to claim 13, wherein calculating comprises
estimating the lost Doppler data by multiplying a predicted
spectrum from temporal past of the lost Doppler data and a
predicted spectrum from temporal future of the lost Doppler data by
a temporally changing weighting function and adding the
spectra.
15. The method according to claim 14, wherein the temporally
changing weighting function is a cosine function.
16. The method according to claim 12, wherein calculating comprises
calculating a transient response component generated at a preceding
stage portion relative to a wall filter of a data acquisition
unit.
17. The method according to claim 12, wherein calculating comprises
calculating a transient response component generated in a wall
filter and frequency analysis unit of the data acquisition
unit.
18. The method according to claim 12, wherein calculating comprises
calculating the transient response component from a spectrum having
a power dimension by executing positive-negative symmetric post
filter processing, and subtracting comprises subtracting the
transmission component after the post filter processing from the
continuous wave Doppler data having a power dimension.
19. The method according to claim 12, wherein calculating comprises
calculating the transient response component as a time axis
waveform by changing a magnitude of the transient response
component based on a preset step response waveform table, and
subtracting comprises subtracting the transient response component
as the time axis waveform from the continuous wave Doppler data of
the time axis waveform.
20. The method according to claim 12, wherein calculating comprises
calculating the transient response component by using an output
from an A/D converter of a data acquisition unit.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is based upon and claims the benefit of
priority from Japanese Patent Application No. 2010-115547, filed
May 19, 2010; the entire contents of which are incorporated herein
by reference.
FIELD
[0002] Embodiments described herein relate generally to an
ultrasonic diagnostic apparatus and an ultrasonic diagnostic
apparatus control method.
BACKGROUND
[0003] The present application relates to an ultrasonic diagnostic
apparatus which can execute a continuous wave Doppler (CWD)/B
simultaneous mode of simultaneously displaying a Doppler spectrum
image captured by CWD and a tomogram captured by the B mode in
cardiac diagnosis.
[0004] Ultrasonic diagnosis allows to display in real time how the
heart beats or the fetus moves, by simply bringing an ultrasonic
probe into contact with the body surface. This technique is highly
safe, and hence allows repetitive examination. Furthermore, this
system is smaller in size than other diagnostic apparatuses such as
X-ray, CT, and MRI apparatuses and can be moved to the bedside to
be easily and conveniently used for examination. In addition,
ultrasonic diagnosis is free from the influences of exposure using
X-rays and the like, and hence can be used in obstetric treatment,
treatment at home, and the like.
[0005] Recently, in cardiac diagnosis, image diagnosis called PWD
(Pulse Wave Doppler)/B simultaneous mode has been executed by using
such an ultrasonic diagnostic apparatus. The PWD/B simultaneous
mode is a mode of executing Doppler spectrum imaging by continuous
wave Doppler and B-mode tomography at a predetermined timing and
displaying the captured images in real time. The PWD/B simultaneous
mode includes an imaging method called interleaved scan and an
imaging method called segment scan. Interleaved scan is a technique
of repeatedly executing, for example, one B-mode scan per four
times of execution of Doppler scan. Segment scan is a technique of
alternately repeating a period (Doppler segment period) of
repeating transmission/reception in the Doppler mode by a
predetermined number of times and a period (non-Doppler segment
period) of repeating transmission/reception in the B mode by a
predetermined number of times.
[0006] The CWD/B simultaneous mode, however, requires switching of
continuous waves unlike a case in which PWD is used. For this
reason, a B-mode image is displayed in the freeze mode during a
period in which real-time display is performed in the Doppler mode.
This makes it difficult to simultaneously implement real-time
display of both a Doppler spectrum and a B-mode image in the CWD/B
simultaneous mode, although the implementation of such technique is
clinically demanded.
[0007] In order to improve the real-time performance of the CWD/B
simultaneous mode, it is necessary to solve, for example, the
following two problems. One is the problem of losses in
intermittent execution of continuous STFT (Short Time Fourier
Transform) analysis. For example, a large loss of about 50 ms
occurs per frame in B-mode images. Even if interpolation of a loss
of a maximum of about 16 ms is performed for this loss, the problem
of image quality deterioration occurs. The other is the problem of
strong transient responses (30 ms to 100 ms) due to the necessity
to instantly switch B-mode scan and Doppler-mode scan. This
transient response causes noise such as spike noise in a Doppler
spectrum, resulting in degrade of image quality.
[0008] It is possible to handle the problem of losses in
intermittent execution of continuous STFT analysis by using the
spectrum loss interpolation technique disclosed in, for example,
Jpn. Pat. Appln. KOKAI Publication No. 2001-149370, which uses an
ARX model using an ECG waveform as a deterministic external input.
However, there is no corresponding unit for the other problem of
transient responses.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] FIG. 1 is a block diagram showing the arrangement of an
ultrasonic diagnostic apparatus 10 according to an embodiment;
[0010] FIG. 2 is a block diagram showing an example of an
arrangement provided for a Doppler processing unit 24 to implement
a loss interpolation function and a transient response reduction
function;
[0011] FIG. 3 is a view for explaining the operation of the Doppler
processing unit 24 in transient response reduction processing;
[0012] FIG. 4 is a view for explaining the execution timing of
transient response reduction processing;
[0013] FIG. 5 is a view for explaining filter processing equivalent
to transient response reduction processing;
[0014] FIG. 6 is a graph for explaining a transient response;
[0015] FIG. 7 is a graph showing an example of a transient response
spectrum at the time when a wall filter acts;
[0016] FIG. 8 is a graph showing an example of a transient response
spectrum at the time when the wall filter does not act;
[0017] FIG. 9 is a view for explaining the concept of loss
interpolation processing executed by an interpolation processing
unit 24m; and
[0018] FIGS. 10A, 10B, and 10C are views for explaining the effect
of loss interpolation processing.
DETAILED DESCRIPTION
[0019] In general, according to one embodiment, an ultrasonic
diagnostic apparatus is configured to execute an imaging mode of
alternately executing a continuous wave Doppler mode of acquiring
time-series Doppler data by performing continuous wave
transmission/reception with respect to an object and a B mode of
acquiring tomogram data represented by luminance by transmitting
and receiving a pulse wave to and from the object, the apparatus
comprising: a data acquisition unit configured to acquire
continuous wave Doppler data and the tomogram data by alternately
executing the continuous wave Doppler mode and the B mode while
switching the modes; and a display unit configured to
simultaneously display Doppler spectrum information generated based
on the continuous wave Doppler data and a tomogram generated based
on the tomogram data.
[0020] The embodiments will be described below with reference to
the views of the accompanying drawing. Note that the same reference
numerals in the following description denote constituent elements
having almost the same functions and arrangements, and a repetitive
description will be made only when required.
First Embodiment
[0021] FIG. 1 is a block diagram showing the arrangement of an
ultrasonic diagnostic apparatus 10 according to this embodiment. As
shown in FIG. 1, the ultrasonic diagnostic apparatus 10 includes an
ultrasonic probe 12, an input device 13, a monitor 14, an
ultrasonic transmission unit 21, an ultrasonic reception unit 22, a
B-mode processing unit 23, a Doppler processing unit 24, an image
generation unit 25, an image memory 26, an image combining unit 27,
a control processor (CPU) 28, a storage unit 29, an interface unit
30, and a software storage unit 31. The ultrasonic transmission
unit 21, ultrasonic reception unit 22, and the like incorporated in
an apparatus body 11 are sometimes implemented by hardware such as
integrated circuits and other times by software programs in the
form of software modules. The function of each constituent element
will be described below.
[0022] The ultrasonic probe 12 includes a plurality of
piezoelectric transducers which generate ultrasonic waves based on
driving signals from the ultrasonic transmission unit 21 and
convert reflected waves from an object into electrical signals, a
matching layer provided for the piezoelectric transducers, and a
backing member which prevents ultrasonic waves from propagating
backward from the piezoelectric transducers. When ultrasonic waves
are transmitted from the ultrasonic probe 12 to an object P, the
transmitted ultrasonic waves are sequentially reflected by the
discontinuity surface of acoustic impedance of an internal body
tissue, and are received as echo signals by the ultrasonic probe
12. The amplitude of such an echo signal depends on an acoustic
impedance difference on the discontinuity surface by which the echo
signal is reflected. The echo produced when a transmitted
ultrasonic pulse is reflected by the surface of a moving blood
flow, cardiac wall, or the like is subjected to a frequency shift
depending on the velocity component of the moving body in the
ultrasonic transmission direction due to the Doppler effect.
[0023] The input device 13 is connected to the apparatus main body
11 and includes a trackball, various types of switches, buttons, a
mouse, and a keyboard which are used to input, to the apparatus
main body 11, various types of instructions and conditions, an
instruction to set a region of interest (ROI), various types of
image quality condition setting instructions, and the like from an
operator.
[0024] The monitor 14 displays morphological information and blood
flow information in the living body based on video signals from the
image combining unit 27.
[0025] The ultrasonic transmission unit 21 includes a trigger
generation circuit, delay circuit, and pulser circuit (none of
which are shown). The pulser circuit repetitively generates rate
pulses for the formation of transmission ultrasonic waves at a
predetermined rate frequency fr Hz (period: 1/fr sec). The delay
unit gives each rate pulse a delay time necessary to focus an
ultrasonic wave into a beam and determine transmission directivity
for each channel. Changing this delay information can arbitrarily
adjust the transmission direction from the probe transducer
surface. The trigger generation circuit applies a driving pulse to
the ultrasonic probe 12 at the timing based on this rate pulse.
[0026] The ultrasonic reception unit 22 includes an amplification
circuit, A/D converter, and an adder. The amplification circuit
amplifies an echo signal captured via the probe 12 for each
channel. The A/D converter gives the amplified echo signals delay
times necessary to determine reception directivities. The adder
then performs addition processing for the signals. With this
addition, the reflection component of the echo signal from the
direction corresponding to the reception directivity is enhanced,
and a composite beam for ultrasonic transmission/reception is
formed in accordance with the reception directivity and
transmission directivity.
[0027] The B-mode processing unit 23 receives an echo signal from
the ultrasonic reception unit 22, and performs logarithmic
amplification, envelope detection processing, and the like for the
signal to generate data whose signal intensity is expressed by a
luminance level. In this case, changing the detection frequency can
change the frequency band for visualization. This arrangement also
allows to concurrently perform detection processing with two
detection frequencies for one reception data. Using this technique
can generate a bubble image and a tissue image from one reception
signal. The data processed by the B-mode processing unit 23 is
output to the image generation unit 25, and is reconstructed as a
B-mode image whose reflected wave intensity is expressed by a
luminance.
[0028] The Doppler processing unit 24 frequency-analyzes velocity
information from the echo signal received from the reception unit
22 to extract a blood flow, tissue, and contrast medium echo
component by the Doppler effect, and obtains blood flow information
such as an average velocity, variance, and power at multiple
points. The obtained blood flow information is sent to the image
generation circuit 25, and is displayed in color as an average
velocity image, a variance image, a power image, and a combined
image of them on the monitor 14.
[0029] In addition, in order to implement a loss interpolation
function and transient response reduction function (to be described
later), the Doppler processing unit 24 includes a wall filter 24b,
a window function processing unit 24c, a Fourier transform unit
24d, a bandpass filter 24f, a power estimation unit 24g, a bias
pattern calculation unit 24h, a dynamic post filter 2D table 24i, a
time readout unit 24j, an integrator 24k, a difference processing
unit 24l, an interpolation processing unit 24m, and a logarithmic
compression unit 24n, as shown in FIG. 2. The details of processing
executed by each constituent element will be described later.
[0030] The image generation unit 25 generates an ultrasonic
diagnostic image as a display image by converting the scanning line
signal string for ultrasonic scanning into a scanning line signal
string in a general video format typified by a TV format. The image
generation unit 25 is equipped with a storage memory which stores
image data. For example, this unit allows the operator to call up
an image recorded during examination after diagnosis. The image
generation unit 25 also has a function as an image processing
apparatus. When constructing, for example, volume data, the image
generation unit 25 constructs volume data by spatially arranging
scanning line signal strings obtained by ultrasonically scanning a
three-dimensional region or continuous two-dimensional regions and
executing coordinate transformation, interpolation processing, and
the like, as needed. The image generation unit 25 generates a
predetermined three-dimensional image by executing volume rendering
using the obtained volume data, MPR processing by extracting an
arbitrary tomogram in the volume data, and the like. Note that each
type of image processing method or the like in the image generation
unit 25 may be implemented by either a software method or a
hardware method.
[0031] The image memory 26 temporarily stores ultrasonic data
corresponding to a plurality of frames or a plurality of
volumes.
[0032] The image combining unit 27 combines the image received from
the image generation unit 25 with character information of various
types of parameters, scale marks, and the like, and outputs the
resultant signal as a video signal to the monitor 14.
[0033] The control processor (CPU) 28 has the function of an
information processing apparatus (computer) and controls the
operation of the main body of this ultrasonic diagnostic apparatus.
The control processor 28 reads out, from the storage unit 29, a
program for implementing various types of image processing methods
and programs for implementing the transient response reduction
function and loss interpolation function (to be described later),
expands the programs in a memory (not shown), and executes
computation, control, and the like associated with each type of
processing.
[0034] The storage unit 29 stores programs for executing various
kinds of scan sequences, dedicated programs for implementing the
transient response reduction function and loss interpolation
function (to be described later), control programs for executing
image generation and display processing, diagnosis information
(patient ID, findings by doctors, and the like), a diagnostic
protocol, transmission/reception conditions, a body mark generation
program, and other data. The storage unit 29 is also used to store
images in the image memory 26, as needed. It is possible to
transfer data in the storage unit 29 to an external peripheral
device via the interface unit 30.
[0035] The interface unit 30 is an interface associated with the
input device 13, a network, and a new external storage device (not
shown). The interface unit 30 can transfer, via a network, data
such as ultrasonic images, analysis results, and the like obtained
by this apparatus to another apparatus.
(Transient Response Reduction Function and Loss Interpolation
Function)
[0036] The transient response reduction function and loss
interpolation function of the ultrasonic diagnostic apparatus 10,
which are used for imaging based on the CWD/B simultaneous mode,
will be described next. The transient response reduction function
reduces noise due to a transient response by estimating/calculating
a response spectrum (two dimensions including a time domain and a
frequency domain) of a transient response excited and generated by
noise (e.g., direct component (DC) variations or the like caused by
an analog switch) mixed due to intermittent transmission/reception
upon switching between the Doppler mode and the B mode in imaging
based on the CWD/B simultaneous mode, and subtracting the spectrum
from the frequency analysis result. The loss interpolation function
is a function of identifying a system by a parametric model using a
biological signal typified by an ECG (electrocardiogram) waveform
as a deterministic external input, and predicting and interpolating
a loss spectrum when continuous STFT analysis is intermittently
performed by using the identified system, in imaging based on the
CWD/B simultaneous mode.
[0037] Obviously, it is preferable to implement both the loss
interpolation function and the transient response reduction
function described above in the ultrasonic diagnostic apparatus
which performs the CWD/B simultaneous mode. Obviously, however, it
is possible to selectively implement or operate the loss
interpolation function or the transient response reduction
function, as needed. In addition, the CWD/B simultaneous mode to
which the loss interpolation function and the transient response
reduction function are applied may be interleaved scan or segment
scan.
(Transient Response Reduction Processing)
[0038] FIG. 3 is a view for explaining the operation of the Doppler
processing unit 24 in processing (transient response reduction
processing) based on the transient response reduction processing.
As shown in FIGS. 2 and 3, upon receiving I and Q signals from the
processing unit at the end of the preceding stage, the bandpass
filter 24f executes filter processing to pass only a predetermined
band of each signal. The power estimation unit 24g estimates the
power of a Doppler signal based on the I and Q signals after the
filter processing. The bias pattern calculation unit 24h calculates
a bias pattern (an STFT response generated by a transient response)
at the time of switching between a B segment and a Doppler segment.
Note that the calculation technique to be used is not specifically
limited.
[0039] In addition, the dynamic post filter 2D table 24i
dynamically selects a positive-negative symmetric simplified filter
having a power dimension in response to a B mode/CWD mode switching
timing signal from the control processor 28. The time readout unit
24j gives a selected simplified filter a predetermined time
corresponding to a B mode/CWD mode switching timing.
[0040] The integrator 24k estimates a response spectrum component
of a transient response by integrating the bias pattern calculated
by the bias pattern calculation unit 24h with the post filter
output from the time readout unit 24j. The difference processing
unit 24l reduces a noise component (offset value) due to a
transient response by subtracting the estimated response spectrum
of the transient response from the spectrum component output from
the Fourier transform unit 24d.
[0041] The above transient response reduction processing is
executed in CWD/B simultaneous mode imaging in accordance with an
inherent transient response component generated for each switching
operation from a B segment to a Doppler segment, as shown in FIG.
4. Therefore, the subtraction processing of subtracting the
estimated response spectrum component of the transient response
from the (bare) spectrum component detected by the CWD mode in the
filter processing unit 24l is equivalent in effect to adaptive
filter processing, as shown in FIG. 5.
[0042] The above transient response reduction processing makes it
possible to reduce the influence of a transient response caused by
switching from the B mode to the CWD mode even if a transient
response like that shown in FIG. 6 occurs due to variations in the
direct current component of a received Doppler signal. The graph
shown in FIG. 7, which shows temporal changes in spectrum in a
superimposed state, represents a response after wall filter
processing. In contrast, the graph shown in FIG. 8, which shows
temporal changes in spectrum in a superimposed state, represents a
response without wall filter processing. As shown in FIG. 7, the
difference processing unit at the subsequent stage can implement
correction by estimating the influence of the wall filter from a
transient response.
(Loss Interpolation Processing)
[0043] FIG. 9 is a view for explaining the concept of processing
(loss interpolation processing) based on the loss interpolation
function executed in the interpolation processing unit 24m. As
shown in FIG. 9, the interpolation processing unit 24m identifies
parameters characterizing a system and a signal prediction
expression EVP_si(n) by a predetermined mathematical model
(parametric model) using, as inputs, an ECG waveform as an external
input and a spectrum component from which an estimated response
spectrum component of a transient response is subtracted. The
interpolation processing unit 24m then estimates (calculates) and
interpolates a lost signal by using the identified signal
prediction expression EVPsi(n).
[0044] FIGS. 10A, 10B, and 10C are views for explaining the effect
of loss interpolation processing. With the above loss interpolation
processing, for example, interpolating a loss signal estimated as
shown in FIG. 10B for a spectrum having losses as shown in FIG. 10A
can acquire a Doppler spectrum with the loss portions like those
shown in FIG. 100 being interpolated.
[0045] Note that such loss interpolation processing is disclosed
in, for example, Jpn. Pat. Appln. KOKAI Publication No.
2001-149370. As a parametric model, it is possible to use, for
example, an AR (Auto Regressive) model, ARX (Auto Regressive
Exogeneous) model, ARMAX (Auto Regressive Moving Average
Exogeneous) model, FIR (Finite Impulse Response) model, ABARX
model, ARARMAX model, or BJ (Box and Jenkins) model.
[0046] The interpolation processing unit 24m includes a memory
which temporarily stores spectrum components corresponding to a
plurality of segments received from the difference processing unit
24l in chronological order. The interpolation processing unit 24m
uses the spectrum components temporarily stored in the memory to
execute the blend loss interpolation processing of multiplying a
spectrum component corresponding to the front side (temporally
past) of each loss portion and a spectrum component corresponding
to the rear side (temporally future) of each loss portion by a
temporally changing weighting function and adding the products.
This blend loss interpolation processing can acquire a Doppler
signal having smoother time continuity. Using a cosine function as
a temporally changing weighting function, in particular, can
efficiently reduce spike noise generated in two-dimensional
spectrum responses.
(Effects)
[0047] When performing CWD/B simultaneous mode imaging, this
ultrasonic diagnostic apparatus estimates/calculates a response
spectrum of a transient response excited and generated by noise
mixed due to intermittent transmission/reception upon switching
between the Doppler mode and the B mode, and subtracts the spectrum
from a frequency analysis result. This can reduce the noise
component (offset value) originating from the transient response.
As a consequence, the image quality in CWD/B simultaneous mode
imaging can be improved.
[0048] In addition, this ultrasonic diagnostic apparatus identifies
a system by a parametric model using, as inputs, an ECG waveform
and the estimated response spectrum component of the transient
response, and interpolates a lost signal, i.e., a Doppler signal
corresponding to one B-mode frame which is lost by intermittent
transmission/reception due to switching between the Doppler mode
and the B mode. It is therefore possible to interpolate a lost
Doppler signal when performing CWD/B simultaneous mode imaging.
This can reduce the image quality deterioration caused by
losses.
Second Embodiment
[0049] The first embodiment described above has exemplified the
function of reducing transient responses originating from the
preceding stage portion (FE) of the wall filter 24b. In practice,
however, weak transient responses are generated by sampling in the
wall filter 24b (for example, in the CWD mode, sampling is
performed at a frequency twice that in the Fourier transform unit
24d) and sampling for frequency analysis in the window function
processing unit 24c and the Fourier transform unit 24d.
[0050] This apparatus may include an arrangement for reducing
transient responses generated in the wall filter 24b, the window
function processing unit 24c, and the Fourier transform unit 24d in
addition to or independently of the arrangement described in the
first embodiment. Note that it is possible to implement the
arrangement for reducing transient responses generated in the wall
filter 24b, the window function processing unit 24c, and the
Fourier transform unit 24d by providing a function substantially
similar in effect to the transient response reduction function
described in the first embodiment for each filter function.
Third Embodiment
[0051] According to the first embodiment described above, the
difference processing unit 24l reduces an offset value caused by a
transient response by subtracting the estimated response spectrum
component of the transient response from the spectrum component
output from the Fourier transform unit 24d. In contrast to this, it
is possible to reduce an offset value due to a transient response
on the time axis by changing the size of the offset component (the
gain of a step input) using a step response waveform table of I and
Q signals (2ch) before frequency analysis and subtracting the
offset component from the time axis waveform before frequency
analysis.
Fourth Embodiment
[0052] In general, the dynamic range at the preceding stage portion
FE (Front End) of the wall filter 24b may depend on the word length
(the number of bits) of an A/D converter. With the future advent of
a high-speed, high dynamic range A/D converter which can output the
I and Q signals immediately after the mixer and anti-alias filter
or an output from the subsequent stage portion BF (Band-pass
Filter), it is possible to directly calculate a response from the
output and reduce a transient response component by a technique
substantially similar in effect to that in the first
embodiment.
[0053] 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.
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