5.5\ Doppler Spectrum of the Main

Renal Artery and Branches

Fig. 9.21  Doppler spectrum of the main renal artery and branches

5.5.1\ Scanning Method

The PSV is the most important parameter to diagnose renal artery diseases. The angle correction line should be parallel to the real direction of the blood flow instead of the direction of the artery wall.

5.5.2\ Section Structure

Typical patterns of renal artery Doppler spectrum: low resistance, early systolic peak (a) and late systolic peak (b).

5.5.3\ Measurement Method and Normal Value

(b) is the highest point of the spectrum, which means the PSV; (c) is the velocity at the end of the diastolic phase; and (a) is the highest point of the early systolic peak. For measurement of RI: place the cursors at b and c. For measurement of AC: acceleration and AT: accelerating time place the cursors at c and a. The renal artery PSV in healthy adults is <100 cm/s; the normal RI range is 0.55–0.70, with an AC of >3 m/s and an AT of <0.07 s.

5.5.4\ Clinical Application Value

The criteria for a renal artery stenosis are ≥60% reduction in the lumen diameter, a PSV ≥180 cm/s at the stenosis, and RAR ≥3.5. Changes in the downstream spectrum can be used as indirect parameters to diagnose a hemodynamically significant stenosis: AT ≥0.07 s, AC ≤3 m/s2, RI <0.5.