ULTRASOUND IMAGING DEVICE AND METHOD OF GENERATING COLOR DOPPLER IMAGE
A clutter signal mixed in a blood flow signal is reduced in a color Doppler, and blood flow visibility is improved. A combination of parameters that maximize a difference between a blood flow and a clutter (a signal other than the blood flow) is determined by analyzing a reception signal, a clutter estimated value (a value indicating a degree of being estimated as a clutter) is set based on the combination, and a reduction coefficient map (hereinafter, simply referred to as a reduction map) that reduces a clutter signal is generated based on the estimated value. The clutter signal is reduced by multiplying the reception signal (an IQ signal after quadrature detection) by the reduction map.
1 . An ultrasound imaging device comprising:
a transmission and reception unit configured to transmit and receive an ultrasonic wave; a clutter processing unit configured to remove a clutter signal from a reception signal of the ultrasonic wave received by the transmission and reception unit; and a color Doppler calculating unit configured to generate a color Doppler image using the reception signal from which the clutter signal is removed, wherein
the clutter processing unit includes a feature detecting unit configured to detect a feature of the reception signal, a determining unit configured to determine, based on the feature, whether the reception signal is a blood flow signal or a clutter signal, a reduction map generating unit configured to generate, based on a determination result, a reduction map for reducing the clutter signal, and a clutter reducing unit configured to apply the reduction map to the reception signal.
2 . The ultrasound imaging device according to claim 1 , wherein
the feature detecting unit detects, as the feature, a standard deviation of an IQ signal obtained by executing quadrature detection on the reception signal.
3 . The ultrasound imaging device according to claim 1 , wherein
the feature detecting unit sets, as the feature, a variance of a blood flow velocity calculated by the color Doppler calculating unit using an IQ signal before clutter removal processing.
4 . The ultrasound imaging device according to claim 1 , wherein
the feature detecting unit detects a plurality of features, and
the reduction map generating unit generates the reduction map by integrating determination results based on the plurality of features.
5 . The ultrasound imaging device according to claim 4 , wherein
the plurality of features include a standard deviation of an IQ signal obtained by executing quadrature detection on the reception signal and a variance of a blood flow velocity calculated using the reception signal before clutter removal processing.
6 . The ultrasound imaging device according to claim 1 , wherein
the determining unit generates a filter function using, as a cutoff value, a threshold value obtained by histogram analysis of the features, and determine the feature is a blood flow or a clutter.
7 . The ultrasound imaging device according to claim 6 , wherein
the determining unit generates, as the filter function, a plurality of filter functions having different characteristics.
8 . The ultrasound imaging device according to claim 7 , further comprising:
a display unit configured to allow a user to select a degree of clutter reduction processing that differs depending on a difference in the characteristics of the filter functions.
9 . The ultrasound imaging device according to claim 1 , wherein
the clutter processing unit further includes a filter unit that executes processing on the reception signal using a low-pass filter.
10 . The ultrasound imaging device according to claim 9 , wherein
the filter unit executes the processing using a low-pass filter on a reception signal in which clutter is reduced by the clutter reducing unit.
11 . The ultrasound imaging device according to claim 9 , wherein
the feature detecting unit detects the feature using the reception signal after the processing executed by the filter unit using the low-pass filter.
12 . A method of generating a color Doppler image using a signal received by an ultrasonic wave transmission and reception unit of an ultrasound imaging device, the method comprising:
a clutter processing step of removing a clutter signal from a reception signal; and a color Doppler calculating step of generating a color Doppler image using the reception signal from which the clutter signal is removed, wherein
the clutter processing step includes a feature detecting step of detecting a feature of the reception signal, a determination step of determining, based on the feature, whether the reception signal is a blood flow signal or a clutter signal, a reduction map generating step of generating, based on a determination result, a reduction map for reducing the clutter signal, and a clutter reducing step of applying the reduction map to the reception signal.
13 . The method of generating a color Doppler image according to claim 12 , wherein
the feature includes a standard deviation of an IQ signal obtained by executing quadrature detection on the reception signal.
14 . The method of generating a color Doppler image according to claim 12 , further comprising:
a step of applying a low-pass filter to the reception signal after the reception signal is processed in the clutter reducing step.
15 . The method of generating a color Doppler image according to claim 12 , further comprising:
a step of applying a low-pass filter to the reception signal, wherein
the low-pass filter is applied to the reception signal before the feature detecting step.