Ultrasound observation apparatus, method for operating ultrasound observation apparatus, and computer-readable recording medium

Patent metadata

Field	Value
Publication number	US-2016331348-A1
Application number	US-201615222118-A
Country	US
Kind code	A1
Filing date	Jul 28, 2016
Priority date	Dec 22, 2014
Publication date	Nov 17, 2016
Grant date	—

Abstract

An ultrasound observation apparatus for generating an ultrasound image based on an ultrasound signal obtained by an ultrasound probe having an ultrasound transducer for transmitting an ultrasound wave to an observation target and receiving the ultrasound wave reflected from the observation target. The ultrasound observation apparatus includes: a frequency analysis unit that analyzes a frequency of the ultrasound signal to calculate frequency spectra depending on a reception depth and a reception direction of the ultrasound signal; a frequency band setting unit that sets a frequency band used for calculating a feature of each of the frequency spectra by use of parameters associated with a frequency spectrum in each of candidate bands having different bandwidths; a feature calculation unit that calculates the feature of each of the frequency spectra based on the frequency band; and a feature image data generation unit that generates feature image data based on the feature.

First claim

What is claimed is:

1 . An ultrasound observation apparatus for generating an ultrasound image based on an ultrasound signal obtained by an ultrasound probe, the ultrasound probe having an ultrasound transducer for transmitting an ultrasound wave to an observation target and receiving the ultrasound wave reflected from the observation target, the ultrasound observation apparatus comprising:
a frequency analysis unit configured to analyze a frequency of the ultrasound signal to calculate a plurality of frequency spectra depending on a reception depth and a reception direction of the ultrasound signal; a frequency band setting unit configured to set a frequency band used for calculating a feature of each of the frequency spectra calculated by the frequency analysis unit by use of parameters associated with a frequency spectrum in each of a plurality of candidate bands having different bandwidths; a feature calculation. unit configured to calculate the feature of each of the frequency spectra based on the frequency band set by the frequency band setting unit; and a feature image data generation unit configured to generate feature image data for displaying information on the feature calculated by the feature calculation unit, wherein the frequency band setting unit comprises: an envelope curve detection, unit configured to detect an envelope curve of each of the frequency spectra; a parameter extraction unit configured to extract the parameters in the plurality of candidate bands, respectively, the parameters being associated with an approximate line obtained by approximating the envelope curve; a variation calculation unit configured to calculate a variation between two parameters respectively extracted in two candidate bands of the plurality of candidate bands having a predetermined relationship, among the parameters extracted per candidate band by the parameter extraction unit; and a determination unit configured to determine the frequency band based on the variation calculated by the variation calculation unit.

2 . The ultrasound observation apparatus according to claim 1 , wherein
the parameter extraction unit is configured to:
sequentially increase a maximum value of a frequency in each candidate band while fixing a minimum value thereof thereby to set the plurality of candidate bands;
approximate the envelope curve by a line to extract a parameter each time one of the candidate bands is set; and
output the parameter to the variation calculation unit,
if the parameter extraction unit already performs parameter extraction processing at least twice, the variation calculation unit is configured to calculate, as the variation, a difference between a latest parameter and a parameter extracted in a previous parameter extraction processing, if the variation calculation unit already performs variation calculation processing at least twice, the determination unit is configured to compare a latest variation with a variation calculated in a previous variation calculation processing, and, if a sign of the variation changes from zero or one sign to the other sign as a result of comparison, the determination unit is configured to determine, as the frequency band, one of the candidate bands in extracting the parameter in the previous parameter extraction processing, and the parameter extraction unit, the variation calculation unit, and the determination unit are configured to repeatedly perform the parameter extraction processing, the variation calculation processing, and the comparison, respectively, until the determination unit determines the frequency band.

3 . The ultrasound observation apparatus according to claim 2 , wherein the parameter extraction unit is configured to perform a regression analysis on the envelope curve to calculate the line, and to determine a slope of the calculated line as the parameters.

4 . The ultrasound observation apparatus according to claim 1 , wherein
the parameter extraction unit is configured to sequentially increase a maximum value of a frequency in each candidate band while fixing a minimum value thereof thereby to set the plurality of candidate bands, and to approximate the envelope curve by a line in each candidate band thereby to extract the parameters, the variation calculation unit is configured to calculate, as the variation, a difference between the two parameters respectively extracted in the two candidate bands whose bandwidths are adjacent, and the determination unit is configured to calculate an approximate curve in which an absolute value of the variation is represented as a function of a maximum frequency in one of the two candidate bands whose bandwidth is smaller than that of the other of the two candidate bands, and to determine the frequency band based on the maximum frequency when the absolute value is minimum in the approximate curve.

5 . The ultrasound observation apparatus according to claim 1 , wherein
the parameter extraction unit is configured to sequentially increase a maximum value of a frequency in each candidate band while fixing a minimum value thereof thereby to set the plurality of candidate bands, and to approximate the envelope curve by a line in each candidate band thereby to extract the parameters, the variation calculation unit is configured to calculate, as the variation, a difference between the two parameters respectively extracted in the two candidate bands whose bandwidths are adjacent, and the determination unit is configured to calculate an approximate curve in which the variation is represented as a function of a maximum frequency in one of the two candidate bands whose bandwidth is smaller than that of the other of the two candidate bands, and to determine the frequency band based on the maximum frequency when a value of the variation is zero in the approximate curve.

6 . The ultrasound observation apparatus according to claim 2 , wherein the parameter extraction unit is configured to:
calculate a frequency distribution in each of a plurality of projection lines when sampling points on the envelope curve in each candidate band are projected onto the plurality of projection lines; calculate a slope of the line based on one of the projection lines whose statistical dispersion in the frequency distribution is the smallest; and determine the calculated slope of the line as the parameters.

7 . The ultrasound observation apparatus according to claim 2 , wherein the parameter extraction unit is configured to:
calculate a frequency distribution in each of a plurality of projection lines when sampling points on the envelope curve in each candidate band are projected onto the plurality of projection lines; select a projection line among the plurality of projection lines that is used for calculating a slope of the line, based on an index which is defined by use of a mode value and a statistical dispersion in the frequency distribution and takes a larger value as the mode value is larger and takes a larger value as the statistical dispersion is smaller; calculate the slope of the line based on the selected projection line; and determine the calculated slope of the line as the parameters.

8 . The ultrasound observation apparatus according to claim 1 , wherein the feature calculation unit is configured to approximate the envelope curve in the frequency band by a regression analysis, and then to perform an attenuation correction for reducing a contribution of attenuation occurring when the ultrasound wave propagates, thereby to calculate the feature of each of the frequency spectra.

9 . A method for operating an ultrasound observation apparatus that is configured to generate an ultrasound image based on an ultrasound signal obtained by

Assignees

• Olympus Corp

Inventors

• NAKATSUJI Tomohiro

Classifications

• A61B8/5207 Primary

  involving processing of raw data to produce diagnostic data, e.g. for generating an image · CPC title

• A61B8/4444

  related to the probe · CPC title

• A61B8/08

  Clinical applications (A61B8/02, A61B8/04, A61B8/06 take precedence) · CPC title

• A61B8/4483

  characterised by features of the ultrasound transducer · CPC title

• A61B8/12

  in body cavities or body tracts, e.g. by using catheters · CPC title