Figure 1.
Doppler signals of blood velocity recorded from the umbilical artery of a fetal lamb.
Within the Doppler spectrum displayed on the screen of the ultrasound scanner, the on-line estimated maximum velocity and the mean weighted velocity are displayed as a light blue and a black line, respectively. The automatically calculated pulsatility index (PI) and time-average velocity (TAM) values are shown in the lower left corner. The waveform of the blood velocities with positive signals throughout the heart cycle indicate a low resistance to flow in the placenta, i.e. a normal fetoplacental blood flow.
Figure 2.
Sound spectrum analysis in a recording from a fetus with normal umbilical artery blood flow.
The MAXpeak and MAXpeak-15 dB are indicated in the displayed frequencies. The operator classified this recording as “grade 11” on the scale extending from 1 (most abnormal) to 11 (normal signal).
Figure 3.
Sound spectrum analysis in a recording from a fetus with severely abnormal umbilical artery blood flow.
The MAXpeak and MAXpeak-15 dB are indicated in the displayed frequencies. The operator classified this recording as “grade 3” on the scale extending from 1 (most abnormal) to 11 (normal signal).
Figure 4.
Operator auditory scale and pulsatility index for individual Doppler recordings in the embolization model.
Green line: pulsatility index (PI), based on the conventional analysis of Doppler spectrum (right y-axis); red line: sonographer’s auditory perception; blue line: auditory perception supported by visual presentation of the spectrum (left y-axis); n: number of observations per lamb.
Figure 5.
Operator auditory scale and pulsatility index for individual Doppler recordings in the anemia model.
For explanations see the legend of figure 4.
Figure 6.
Operator auditory scale and time average mean velocity for individual Doppler recordings in the embolization model.
Green line: time average mean velocity (TAM) (right y-axis); red line: sonographer’s auditory perception; blue line: auditory perception supported by visual presentation of the spectrum (left y-axis); n: number of observations per lamb.
Figure 7.
Operator auditory scale and time average mean velocity for individual Doppler recordings in the anemia model.
For explanations see the legend of figure 6.
Table 1.
Correlation between operator auditory scale, Doppler spectrum parameters and sound spectrum analysis of umbilical artery Doppler recordings in the fetal lamb embolization model.
Table 2.
Correlation between operator auditory scale, Doppler spectrum parameters and sound spectrum analysis of umbilical artery Doppler recordings in the fetal lamb anemia model.
Figure 8.
Sound spectrum analysis in the embolization and anemia models, respectively.
PI: pulsatility index; TAM: time average mean velocity; blue symbols: maximum energy content (MAXpeak); green symbols: frequency band at maximum energy level minus 15 dB (MAXpeak-15 dB).