Table 2.

Spectral waveform analysis of pulmonary arterial flow patterns in different etiologies

	Pneumonia	Lung atelectasis	Tumor consolidation	Pulmonary embolism
Presence of flow signal	Detected	Detected	Detected	None detected
Flow signal density	High	Low	Low	None
PI ([Peak systolic velocity − End diastolic velocity]/Mean velocity)	Median	High	Low	None
RI ([Peak systolic velocity − End diastolic velocity]/Peak systolic velocity)	Median	High	Low	None
AT (duration from the beginning to the peak systolic velocity)	Median	Low	High	None
The feature of blood flow	Moderate-impedance flow	High-impedance flow	Low-impedance flow	No flow