01-17 Renal Imaging

Question 1

Concept of phases in contrast CT of kidneys

Answer 1

CT is really 4D (includes time).
—”Kidney appearance changes in “phases” after intravenous administration of iodinated contrast (xray dye) as the contrast passes through the kidney”

Question 2

What are you looking for as you interpret the different phases of a contrast-enhanced CT of the kidney?

Answer 2

1. symmetrical?
   —if asymmetrical: “right kidney does not advance beyond early medullary phase”
2. areas that aren’t lighting up that should or are lighting up differently?
   —renal masses
3. are there bright spots pre-contrast phase?
   —stones
4. is there contrast leaking out?
   —bleeding or urine leak (differentiate by the PHASE)

Question 3

Appearance of chronic versus acute hydro

Answer 3

it takes some time to stretch out the calicies; this isn’t hyperplasia, just stretching of existing tissue
—big ballooning hydros are chronic
[IMAGE q3]

Question 4

Image of chronic hydro

Answer 4

[IMAGE q4]

Question 5

Masses that take up dye vs. don’t

Answer 5

If it takes up dye it’s vascularized/alive (e.g. tumor)
—look at mass borders; going down Renal v.?
If not than it’s dead (e.g. cyst)

Question 6

Bosniak Criteria

Answer 6

—Rads scale to grade what masses to biopsy
—uses CT
—cut-off: are septae vascularized

Question 7

Radio frequency ablation

Answer 7

IR procedure for tumors

—not radiation; heats up the tumor from inside out

Question 8

Renal Angiomyolipoma

Answer 8

abnormal renal mass
—nonhomogenous
—ripplpes of fat throughout
—nonmalignant, but can bleed
—can tx by coiling it off

Question 9

What can you see on renal U/S?

Answer 9

1. Renal Size
2. Enchogenicity (compare renal parenchyma/liver)
3. Hydronephrosis
4. FLOW

Question 10

Units for CT radiodensity?

Answer 10

Hounsfield units
-1000 = air
0 = water
1000 = dense cortical bone

Question 11

Stone appearance on U/S w/ Doppler on?

Answer 11

“twinkle artifact”