Flow turbulence or twinkling artifact? A primary observation on the intrarenal color Doppler sonography.

OBJECTIVE

The objective of this report was to describe and potentially explain differences of intrarenal color Doppler sonography (CDUS) manifestations between blood flow turbulence and twinkling artifact.

METHODS

We retrospectively reviewed 32 cases with appearance of focally increased color Doppler signal on intrarenal CDUS from May 1, 2007, to February 28, 2009. Indications for intrarenal CDUS in 32 cases were suspicion of renovascular hypertension, investigation of complications related to renal biopsy, or hematuria. Characteristics of the color Doppler signal, relationship between color Doppler signal and renal vessels, and the spectral Doppler sampled at the anatomic site of the focal color signal were analyzed. The value and pitfall of color Doppler in the diagnosis of the intrarenal vascular abnormality and detection of renal calculus are discussed.

RESULTS

Thirty-two cases with focally increased color Doppler during sonography of native or transplanted kidneys were classified into two groups: (1) turbulent blood flow-intrarenal vascular abnormalities including intrarenal arteriovenous fistula (15 cases) and intrarenal artery stenosis (eight cases); and (2) color Doppler artifact-twinkling produced by renal calculus (nine cases). There were differences in the characteristics of the color Doppler signal, the relationship between the color signal and renal vessel, and the spectral waveform on CDUS between flow turbulence and twinkling.

CONCLUSION

Flow turbulence and twinkling artifact on intrarenal CDUS are distinguishable by analyzing the manifestations on intrarenal CDUS. Proper color Doppler setting and spectral Doppler play important roles in differentiation between flow turbulence in renal vascular abnormalities and twinkling produced by renal stones.