B5.079 Prework 1: Renal Imaging Flashcards

1
Q

pros and cons of conventional radiographs

A

pros: cheap and quick
cons: poor soft tissue detail & radiation

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2
Q

pros and cons of CT

A

pros: high spatial and contrast resolution, relatively short exam, easy to access
cons: high radiation dose, risks of iodinated contrast

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3
Q

pros and cons of nuclear scintigraphy

A

pros: provides functional data
cons: poor resolution, radiation exposure

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4
Q

pros and cons of ultrasound

A

pros: relatively cheap and quick, no radiation
cons: cant visualize ureters, operator dependent

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5
Q

is MRI used for kidney imaging?

A

not often

2nd or 3rd line only

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6
Q

2 main categories of renal imaging

A

structural: xray, CT, US
functional: nuclear medicine

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7
Q

how does a CT of the kidney work

A

produce cross sectional images of the kidney utilizing an xray source and detector on a rotating gantry
often performed with IV contrast
can produce images in any plane

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8
Q

4 phases of renal imagining w contrast

A
  1. pre contrast
  2. post contrast: corticomedullary
  3. post contrast: nephrogenic
  4. delayed: pylographic
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9
Q

why are there different phases of renal imaging?

A

each phase highlights a different portion of the kidney and allows detection of different disease processes

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10
Q

pre-contrast imaging uses

A

renal calcifications

no differentiation

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11
Q

corticomedullary phase imaging description

A

20-40 s after contrast admin

cortex brighter than medulla/pelvis (kidneys perfuse from outside in)

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12
Q

nephrogenic phase imaging description

A

60-120 s after contrast admin

equal distribution of contrast between cortex and medulla

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13
Q

pyelographic phase imaging description

A

minutes to hours after contrast admin

contrast in calices and pelvis

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14
Q

early post contrast imaging uses

A

detects and characterizes solid vs cystic cortical masses

i.e. RCC vs simple cyst

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15
Q

delayed contrast imaging uses

A

evaluates renal pelvis and ureter for mass lesions

i.e. UCC

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16
Q

appearance of cyst on post contrast CT

A

dark, homogenous mass

17
Q

appearance of RCC on post contrast CT

A

mass with mixed densities throughout, lighter than cyst

18
Q

how does an ultrasound work for kidney imagine

A

high frequency sound waves are produced by a piezoelectric crystal in a transducer and transmitted into the tissues via a gel medium
transducer also receives reflected sound waves and converts them back into electrical currents for image reconstruction

19
Q

2 main factors in ultrasound image reconstruction

A

travel time for a reflected beam of sound (depth)

degree to which it is reflected (acoustic impedance)

20
Q

high acoustic impedance on US

A

fat, air, bone, metal
appear whiter
hyperechoic

21
Q

low acoustic impedance on US

A

water
appear dark
hypoechoic

22
Q

normal kidney appearance on US

A

edge is lighter
cortex darker
collection of renal sinus fat in center appears light

23
Q

hydronephrosis on US

A

dark circles in center of kidney due to urine filled calices

24
Q

use of Doppler imaging on kidney

A

can determine direction and speed of blood flow within the structure
helps determine is there is vasculature in a mass (RCC vs fluid filled cyst)

25
how does nuclear medicine imaging of the kidney work
utilizes selective binding and/or filtering of various radioactive compounds (radionuclides) most common renal scintigraphic study is a MAG-3 renal scan
26
what is MAG-3
compound which is partially filtered from the blood via the glomerulus and partially secreted from the tubules labeled with radioactive technicium
27
uses of renal scintigraphy
can construct an image with radioactivity and also quantitate amount of activity in a given structure over time evaluates renal function and can be used to determine GFR
28
normal activity vs time curve for a kidney
activity rises to a peak and then begins to decline steadily | decreases faster with administration of Lasix
29
activity vs time curve during hydronephrosis
activity constantly rises and never falls, even with Lasix administration radioactive material cannot be excreted due to blockage
30
activity vs time curve in nonobstructed but dilated kidney
rises to a peak, but eventually falls off with Lasix infusion