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Renal doppler ultrasound
This document provides information on performing and interpreting renal Doppler ultrasounds. It discusses the optimal approaches for imaging the renal arteries, including the anterior, oblique, and flank approaches. It also outlines criteria for evaluating renal artery stenosis, including peak systolic velocity measurements and the renal-aortic ratio. Common renal pathologies that can be identified with Doppler ultrasound are also summarized, such as fibromuscular dysplasia, atherosclerosis, aneurysms, and hydronephrosis.
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Renal doppler ultrasound
- 1. Renal Doppler Ultrasound Theessentials Dr/Ahmed Bahnassy Consultant Radiologist MBCHB-MSc-FRCR(UK)
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- 5. Transverse B-mode viewof the abdominal aorta and right renal artery from an anterior approach. The ultrasound probe is oriented at midline and the Doppler cursor placed in the proximal right renal artery. The angle of incidence of the Doppler beam to the flow is unacceptable at approximately 89 degrees. By moving the probe to the left of midline and angling toward the patient’s right, an acceptable Doppler angle of 60 degrees is achieved
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- 8. The Doppler samplevolume is placed within the proximal right renal artery. In this view, an acceptable Doppler angle of 60 degrees or less is easily obtained.
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- 11. Methods of evaluationof RA • Direct visualization • with Doppler • throughout the Main • renal artery and all • accessory renal • arteries • • Indirect Evaluation • – Doppler of the • segmental/interlobar • renal arteries at the • upper, mid and lower • renal poles • The most reliable approach combines the two methods.
- 12. Criteria for RenalArtery Stenosis Direct Evaluation • Velocities greater than 200 cm/sec have been shown to indicate a >60% RAS. • Post-stenotic turbulence must be documented beyond any focal velocity increase to confirm stenosis. • Bruits seen in Color Doppler or in the spectral waveform can also increase diagnostic confidence and aid in localization of a stenosis. • The RAR is calculated by dividing the highest peak systolic velocity in the renal artery by the normal aortic velocity. An RAR greater than 3.5 is considered abnormal. The use of the RAR instead of the absolute PSV value is preferable since hypertension itself can cause increased PSV velocities in all the vessels in hypertensive patients
- 13. Image A isa color Doppler image of a stenotic right renal artery origin. A color bruit is seen in the tissue surrounding the area of the post stenotic turbulence. The presence of the bruit can help to identify the location of the stenosis and increase diagnostic confidence.
- 14. A Doppler reading(B)obtained near the renal artery origin shows velocities over 600 cm/s in systole and over 300 cm/s in diastole consistent with a high grade stenosis.
- 15. Image C showsa spectral waveform obtained in the area of poststenotic turbulence just beyond the maximal area of stenosis. The velocity is lower at 317 cm/s and the waveform profile is irregular due to the turbulent flow.
- 16. Tardus–parvus waveform ina patient with RA stenosis. Note the delayed and dampened upstroke yielding a rounded appearance to the waveform.
- 17. The ESP isdetected on each waveform. • In some cases, the ESP is the highest peak, but in others, the highest peak occurs later in systole. • The AT is always measured to the first systolic peak, which is the ESP in normal waveforms. Since the ESP is absent on abnormal waveforms, the AT is measured from the beginning of systole to the systolic peak. These waveforms are termed tardus parvus due to the delayed systolic acceleration
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