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| Fig. 1: Dopler sample of the right main renal a. near the hilum shows a normal peak systolic velocity. |
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| Fig. 2: Doppler sample in the mid main renal a. shows a higher velocity. |
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| Fig. 3: Doppler sample in the main renal a. shows an abnomally high velocity, consistent with a stenosis near the origin. "The most accurate use of parameters was found to be a combination of either peak systolic velocity greater than 180 cm/sec or renal aortic ratio greater than 3.0. Indirect parameters were not found to be useful in predicting the presence or absence of renal artery stenosis" - House et al., 1999. |
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| Fig. 4: Aortic velocity is less than proximal right renal a.
Key article:
Imaging of Renovascular Hypertension: Respective Values of Renal Scintigraphy, Renal Doppler US, and MR Angiography by Soulez, et al., Radiographics (2000) |
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| Fig. 5: Oddly the resistive index in the kidney is high, the opposite of what one might expect. Two approaches are used to detect RAS with Doppler US: direct visualization of the renal arteries and analysis of intrarenal Doppler waveforms. Regarding direct visualization, four criteria are used to diagnose significant proximal stenosis or occlusion of a renal artery: (a) An increase in peak systolic velocity in the renal artery (in the literature, the threshold for significant RAS is 100–200 cm/sec); (b) a renal-to-aortic ratio of peak systolic velocity greater than 3.5; (c) turbulent flow in the poststenotic area; and (d) visualization of the renal artery without detectable Doppler signal, a finding that indicates occlusion. |
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| Fig. 6 |
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| Fig. 7: Near the hilum on the left, the main renal a. velocity is nearly normal. |
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| Fig. 8: Near the aorta, the velocity is elevated. |
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| Fig. 9: Again, the resistive index is high which is not supportive of renal artery stenosis. What else do you notice about this picture? |
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| Fig. 10 |
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| Fig. 11: This large area of hypoechognicity with scattered specular reflectors has the appearance of an abcess in this recently postoperative patient. |
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| Fig. 12 |
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| Fig. 13: The Williams syndrome website has some good, basic info: http://www.williams-syndrome.org/ |
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3 Y/O MALE W/ WILLIAMS SYNDROME AND HYPERTENSION