Method and apparatus for automatic optimization of doppler imaging parameters

• US 8,142,361 B2
• Filed: 08/26/2008
• Issued: 03/27/2012
• Est. Priority Date: 08/28/2007
• Status: Active Grant

• Current Assignee: Shenzhen Mindray Bio-Medical Electronics Co., Ltd. (Excelsior Union Ltd.)
• Original Assignee: Shenzhen Mindray Bio-Medical Electronics Co., Ltd. (Excelsior Union Ltd.)
• Inventors: Zhang, Yu, ZHANG, Guanxi
• Primary Examiner(s): Jung, Unsu
• Application Number:
  US12/198,569
• Publication Number:
  US 20090062654A1
• Time in Patent Office: 1,309 Days
• Field of Search: None
• US Class Current: 600/455
• CPC Class Codes: A61B 8/06 Measuring blood flow measuring volume flow in general G01F, e.g. G01F1/66, G01F1/72; measuring speed of fluids in general G01P5/00
• CPC Class Codes: A61B 8/488 involving Doppler signals
• CPC Class Codes: G01S 15/8981 Discriminating between fixed and moving objects or between objects moving at different speeds, e.g. wall clutter filter
• CPC Class Codes: G01S 15/8986 with measures taken for suppressing velocity ambiguities, i.e. anti-aliasing
• CPC Class Codes: G01S 7/5205 Means for monitoring or calibrating

Abstract

A method and apparatus are disclosed for automatic optimization of Doppler imaging parameters. The method includes obtaining and storing at least two characteristic spectral lines at a predetermined pulse repetition frequency. The method further includes optimizing at least one of the Doppler imaging parameters based on the stored at least two characteristic spectral lines and a predetermined mean noise power. In one embodiment, the characteristic spectral lines are obtained by collecting in real time the Doppler spectral lines generated at the predetermined pulse repetition frequency within a predetermined time period, and processing the collected Doppler spectral lines in real time without storing them.

Claims

1. A method for automatic optimization of Doppler imaging parameters including at least one of a pulse repetition frequency and a baseline, the method comprising:

obtaining at least two characteristic spectral lines at a predetermined pulse repetition frequency, wherein the at least two characteristic spectral lines include a maximum power spectral line and a mean power spectral line;

storing the at least two characteristic spectral lines; and

optimizing at least one of the Doppler imaging parameters based on the stored at least two characteristic spectral lines and a predetermined mean noise power,

wherein the at least two characteristic spectral lines are obtained by collecting in real time Doppler spectral lines generated at the predetermined pulse repetition frequency within a predetermined time period, and processing the collected Doppler spectral lines in real time without storing them

wherein optimizing the at least one of the Doppler imaging parameters comprises;

filtering out power values of the maximum power spectral line and the mean power spectral line within a frequency cutoff range of wall filtering, thereby obtaining a new maximum power spectral line and a new mean power spectral line;

determining a frequency bin corresponding to a minimum power value of the new maximum power spectral line;

deciding whether or not a multi-aliasing occurs by comparing a power value of the new mean power spectral line corresponding to the determined frequency bin with a first threshold value, wherein if the power value of the new mean power spectral line corresponding to the determined frequency bin is larger than the first threshold value, it is determined that the multi-aliasing occurs;

otherwise, no multi-aliasing occurs;

searching for boundaries of a blood flow signal based on the new maximum power spectral line and the predetermined mean noise power if no multi-aliasing occurs, wherein the boundaries of the blood flow signal include both a positive frequency boundary and a negative frequency boundary;

adjusting the pulse repetition frequency down to a minimum value and the baseline to a center of a display area if no boundaries of the blood flow signal are found; and

adjusting at least one of the Doppler imaging parameters based on the boundaries of the blood flow signal if the boundaries of the blood flow signal are found.

2. The method according to claim 1, wherein the predetermined pulse repetition frequency is selected from one of a system-allowable maximum pulse repetition frequency, a maximum pulse repetition frequency at a current detection depth, or a maximum pulse repetition frequency under a current examination mode.

3. The method according to claim 1, wherein obtaining the at least two characteristic spectral lines comprises:

collecting in real time the Doppler spectral lines generated at the predetermined pulse repetition frequency;

obtaining a final maximum power spectral line by selecting a larger power value in each frequency bin between a currently stored maximum power spectral line and a currently collected Doppler spectral line within the predetermined time period;

obtaining a total power spectral line by accumulating in real time a power value in each frequency bin of the Doppler spectral lines collected in real time within the predetermined time period; and

obtaining the mean power spectral line by dividing the total power spectral line by the number of the Doppler spectral lines collected in real time within the predetermined time period.

4. The method of claim 1, wherein the first threshold value depends on the predetermined mean noise power.

5. The method of claim 1, wherein searching for the boundaries of the blood flow signal comprises:

searching for the negative frequency boundary of the blood flow signal in the new maximum power spectral line, which further comprises;

searching from the determined frequency bin in a positive frequency direction;

if the maximum power values in a number of consecutive frequency bins are larger than a second threshold value, determining that the negative frequency boundary of the blood flow signal is found; and

, if not, continuing searching in the positive frequency direction until a maximum frequency bin and then searching from a minimum frequency bin up to the determined frequency bin; and

searching for the positive frequency boundary of the blood flow signal in the new maximum power spectral line, which further comprises;

searching from the determined frequency bin in a negative frequency direction;

if the maximum power values in a number of consecutive frequency bins are larger than the second threshold value, determining that the positive frequency boundary of the blood flow signal is found; and

, if not, continuing searching in the negative frequency direction until the minimum frequency bin and then searching from the maximum frequency bin down to the determined frequency bin.

6. The method of claim 5, wherein the second threshold value depends on the predetermined mean noise power.

7. The method according to claim 1, wherein adjusting at least one of the Doppler imaging parameters based on the boundaries of the blood flow signal comprises adjusting the pulse repetition frequency and the baseline based on the following equations:

8. The method according to claim 1, wherein the predetermined time period is equal to at least one cardiac cycle.

9. The method according to claim 1, wherein the predetermined mean noise power is measured in advance at different detection depths under different sampling gate width conditions.

10. A non-transitory computer-readable medium comprising program code for causing a computer to perform a method for automatic optimization of Doppler imaging parameters including at least one of a pulse repetition frequency and a baseline, the method comprising:

obtaining at least two characteristic spectral lines at a predetermined pulse repetition frequency, wherein the at least two characteristic spectral lines include a maximum power spectral line and a mean power spectral line;

storing the at least two characteristic spectral lines; and

optimizing at least one of the Doppler imaging parameters based on the stored at least two characteristic spectral lines and a predetermined mean noise power,

wherein the at least two characteristic spectral lines are obtained by collecting in real time the Doppler spectral lines generated at the predetermined pulse repetition frequency within a predetermined time period, and processing the collected Doppler spectral lines in real time without storing them

wherein optimizing the at least one of the Doppler imaging parameters comprises;

filtering out power values of the maximum power spectral line and the mean power spectral line within a frequency cutoff range of wall filtering, thereby obtaining a new maximum power spectral line and a new mean power spectral line;

determining a frequency bin corresponding to a minimum power value of the new maximum power spectral line;

deciding whether or not a multi-aliasing occurs by comparing a power value of the new mean power spectral line corresponding to the determined frequency bin with a first threshold value, wherein if the power value of the new mean power spectral line corresponding to the determined frequency bin is larger than the first threshold value, it is determined that the multi-aliasing occurs;

otherwise, no multi-aliasing occurs;

searching for boundaries of a blood flow signal based on the new maximum power spectral line and the predetermined mean noise power if no multi-aliasing occurs, wherein the boundaries of the blood flow signal include both a positive frequency boundary and a negative frequency boundary;

adjusting the pulse repetition frequency down to a minimum value and the baseline to a center of a display area if no boundaries of the blood flow signal are found; and

adjusting at least one of the Doppler imaging parameters based on the boundaries of the blood flow signal if the boundaries of the blood flow signal are found.