Renal Ultrasound

Question 1

Renal ultrasound is an anatomic or a functional study?

Answer 1

Anatomic

Question 2

Echogenicity: hyperechoic means what?

Answer 2

Brighter/white image

Question 3

Echogenicity: hypoechoic means what?

Answer 3

Darker/black image

i.e. the are less echos reflected, so no image is picked up by the transducer

Question 4

Echogenicity: Isoechoic means what?

Answer 4

similar echogenicity to a comparable area. For the kidney, the reference is the echogenicity of a healthy liver.

Question 5

Gerota’s fascia and perinephric fat has what echogenicity?

Answer 5

Hyperechoic (brighter) area surrounding the kidney

Question 6

Renal cortex appears how?

Answer 6

Homogenous, almost isoechoic grey area in the periphery

Question 7

Renal sinus appears how?

Answer 7

Hyperechoic central area

Question 8

Describe how hydronephrosis would appear

Answer 8

Hypoechoic enlargement of the renal pelvis and calyces

Question 9

What is the formula for Resistive Index (RI)?

What is a normal RI?

Answer 9

RI = (systolic - diastolic) / systolic

Normal RI = 0.6

Question 10

If there is renal obstruction, what happens to the resistive index?

What level RI indicates obstruction?

Answer 10

It increases.

RI > 0.7 or difference between kidneys > 0.1

Question 11

Name some causes for an elevated Resistive index?

Answer 11

transplant rejection, obstruction, ATN, pyelonephritis, severe hypotension, or an acute vascular event (i.e. renal vein thrombosis)

Question 12

What happens to the Resistive index in renal artery stenosis?

Answer 12

RI decreases.

RI = (systolic - diastolic) / systolic
In RAS, there is decreased systolic flow (denominator), therefore RI will decrease