Ultrasonic diagnostic apparatus and elastic evaluation method

Abstract

An ultrasonic diagnostic apparatus and a method having a highly-reliable elastic evaluation unit for tissues. The invention includes a signal processing unit that processes received data obtained after ultrasonic waves are transmitted and received to/from an inspection target through a probe. An ROI detection unit of the processing unit obtains a distance index indicating a region proper for an elastic evaluation based on brightness distribution of the received data obtained by transmitting and receiving first ultrasonic waves to/from the probe, and sets an ROI based on the distance index. Then, second ultrasonic waves are transmitted to the ROI to generate shear waves. An elastic evaluation unit calculates a shear wave velocity based on the received data obtained by transmitting and receiving third ultrasonic waves in the ROI, and outputs the shear wave velocity and an elastic evaluation value of the ROI as a reliability index.

1 . An ultrasonic diagnostic apparatus comprising:
 a transmission/reception unit that transmits and receives first, second, and third ultrasonic waves to/from an inspection target through a probe that transmits and receives ultrasonic waves; and   a processing unit that processes received data obtained from the inspection target,   wherein the processing unit can determine a measurement region on the basis of image information formed using the received data obtained by transmitting and receiving the first ultrasonic waves, can transmit the second ultrasonic waves to the determined measurement region to generate shear waves, can calculate a shear wave velocity using the received data obtained by transmitting and receiving the third ultrasonic waves to/from the measurement region, and can output the shear wave velocity and an elastic evaluation value of the measurement region.   
     
     
         2 . The ultrasonic diagnostic apparatus according to  claim 1 , wherein the processing unit calculates an index indicating a region proper for an elastic evaluation on the basis of brightness distribution of the inspection target calculated using the image information, and determines the measurement region on the basis of the index. 
     
     
         3 . The ultrasonic diagnostic apparatus according to  claim 2 ,
 wherein the processing unit includes:   an ROI detection unit that calculates the index on the basis of the brightness distribution, and detects the measurement region on the basis of the calculated index, and   an elastic evaluation unit that performs the elastic evaluation of the measurement region using the shear wave velocity measured at the measurement region.   
     
     
         4 . The ultrasonic diagnostic apparatus according to  claim 2 , wherein the processing unit calculates the index on the basis of a statistical value of brightness in a certain range of the inspection target, and uses, as the statistical value, the average value of brightness after an adjustment process by an S-shaped function. 
     
     
         5 . The ultrasonic diagnostic apparatus according to  claim 2 , wherein a display unit is further provided, and the processing unit displays the value of the index on the display unit as a color map of the inspection target. 
     
     
         6 . The ultrasonic diagnostic apparatus according to  claim 2 , wherein a display unit is further provided, and the processing unit displays the value of the index using the size of a frame line of the measurement region displayed on the display unit, the type of line, a color, or the size of a frame of the measurement region. 
     
     
         7 . The ultrasonic diagnostic apparatus according to  claim 2 , wherein a display unit is further provided, and the processing unit calculates the elastic evaluation value of the measurement region on the basis of the index, and displays the elastic evaluation value of the measurement region on the display unit. 
     
     
         8 . The ultrasonic diagnostic apparatus according to  claim 7 , wherein the processing unit displays dispersion or standard deviation of the elastic evaluation values calculated at the plural measurement regions on the display unit as indexes to determine unevenness of elasticity of the measurement target. 
     
     
         9 . The ultrasonic diagnostic apparatus according to  claim 1 , wherein the processing unit measures the wavefront characteristic amount of the shear waves at a first measurement point and a second measurement point using the received data obtained by transmitting and receiving the third ultrasonic waves to/from the measurement region, calculates a frequency distribution of peak-to-times of the shear waves at the first measurement point and the second measurement point, and calculates the shear wave velocity and the elastic evaluation value of the measurement region through a correlation operation of the frequency distribution. 
     
     
         10 . The ultrasonic diagnostic apparatus according to  claim 9 , wherein a display unit is further provided, and the processing unit displays a correlation value calculated through the correlation operation of the frequency distribution on the display unit as the elastic evaluation value of the measurement region. 
     
     
         11 . The ultrasonic diagnostic apparatus according to  claim 10 , wherein the processing unit displays dispersion or standard deviation of the elastic evaluation values calculated at the plural measurement regions on the display unit as indexes to determine unevenness of elasticity of the measurement target. 
     
     
         12 . The ultrasonic diagnostic apparatus according to  claim 9 , wherein the processing unit calculates a histogram of peak-to-times of the shear waves as information representing a frequency distribution of peak-to-times of the shear waves. 
     
     
         13 . An elastic evaluation method comprising the steps of:
 transmitting and receiving first ultrasonic waves to/from an inspection target through a probe that transmits and receives ultrasonic waves;   generating brightness distribution of an inspection target on the basis of received data obtained from the inspection target;   determining a measurement region on the basis of the generated brightness distribution;   transmitting second ultrasonic waves to the determined measurement region to generate shear waves;   calculating a shear wave velocity using the received data obtained by transmitting and receiving third ultrasonic waves to/from the measurement region; and   outputting the shear wave velocity and an elastic evaluation value of the measurement region.   
     
     
         14 . The elastic evaluation method according to  claim 13 , further comprising the steps of:
 calculating an index indicating a region proper for an elastic evaluation on the basis of the brightness distribution of the inspection target, and   determining the measurement region on the basis of the calculated index.   
     
     
         15 . The elastic evaluation method according to  claim 13 , further comprising the steps of:
 measuring the wavefront characteristic amount of the shear waves at a first measurement point and a second measurement point using the received data obtained by transmitting and receiving the third ultrasonic waves to/from the measurement region;   calculating a frequency distribution of peak-to-times of the shear waves at the first measurement point and the second measurement point; and   calculating the shear wave velocity and the elastic evaluation value of the measurement region through a correlation operation of the frequency distribution.   
     
     
         16 . The elastic evaluation method according to  claim 15 , further comprising the step of:
 using dispersion or standard deviation of the elastic evaluation values calculated at the plural measurement regions as indexes to determine unevenness of elasticity of the measurement target.   
     
     
         17 . An ultrasonic diagnostic apparatus comprising:
 a probe that transmits and receives ultrasonic waves;   a measurement region determination unit that determines a measurement region on the basis of image information formed using the received data obtained by transmitting and receiving first ultrasonic waves by the probe;   a evaluation unit that generates shear waves by transmitting second ultrasonic waves to the determined measurement region by the probe, measures a feature value of the shear waves at the first measurement point and the second measurement point of the shear waves at each measurement point in the determined measurement region by transmitting and receiving the first ultrasonic waves by the probe, calculates a frequency distribution of the feature value at each measurement point, calculates a shear wave velocity and the elastic evaluation value of the measurement region through a correlation operation of the frequency distribution; and   a display unit that displays the shear wave velocity and/or the elastic evaluation value.   
     
     
         18 . The ultrasonic diagnostic apparatus according to  claim 17 , wherein the feature value is peak-to-times of the shear waves at the first measurement point and the second measurement point.