Functional Renal Flashcards
Typical rate for GFR
125 ml/min
first step in urine formation
glomerular filtration
water and solutes are filtered into the capsule due to
hydrostatic pressure
where does tubular reabsorption occur?
PCT
nutrients, ions, majority of the water is reabsorbed back into the blood by … throughout…
passive and active mechanisms
through PCT, loop of Henle and DCT
which process is an active one?
tubular secretion
capacity of bladder
700-800ml
where do we find the functional or parenchymal tissue in the kidney?
medulla
blood back to filtrate
tubular secretion
filtrate back to blood
tubular reabsorption
functional RPs
MAG3, DTPA
morphological RPs
DMSA, Gluco
tubular secreted agent
MAG3
glomerular filtrated agent
DTPA
agent that has the higher protein binding
MAG3
why does MAG3 have high T:NT?
can’t diffuse into extravascular spaces
agent of choice for obstruction cases or highly impaired renal functions
MAG3
agent used for ERPF
MAG3
mag3 first pass extraction = %?
dtpa first pass extraction = %?
mag3 = 50%
dtpa = 20%
70% dose excreted in urine at 30mins
mag3
50% of dose excreted in urine at 2hrs
dtpa
agent used for GFR
dtpa
indication for functional renal scans
- for baseline or followup of kidney differential function and PERFUSION
- trauma, failure
- eval transplant (rejection, urine leak, atn)
patient prep for functional renal scans
- well hydrated
- void before imaging
what is the minimum amount of water a patient needs to have?
300-500ml
kidneys are found in the ___ FOV
top of the FOV
method of admin
IV bolus
dose of RP
90-370 MBq
2 sequential phasing
phase 1
renal perfusion (flow)
2 sequential phasing
phase 2
function (dynamic)
relative time frame for imaging
flow = 2 mins
dynamic = 25-30 mins
post-void static = 2.5 mins
renogram
TAC that shows perfusion uptake and excretion of RP in each kidney
aorta ROI
assesses perfusion and quality of bolus
dynamic function renogram has 3 phases
- blood flow
- cortical function
- clearance
peak activity in healthy, hydrated patient
3-5 min post injection
bladder is seen by ..
4-8 mins
blood flow aka
perfusion, vascular
cortical function aka
cortical uptake, parenchymal, tubular concentration, secretory
clearance aka
excretion, collecting system
time to peak
by 5 mins
(typically, 3-5 min)
20 min/max count ratio
ratio <0.35
what is the 20min/max count ratio measuring?
residual cortical activity based on counts at 20 mins to max counts
= transit time in kidney
differential cortical retention
difference <20%
T1/2 excretion
<20 mins
(typically, 8-12 mins)
what does T1/2 represent?
time for half the peak activity to be cleared from the kidney
what is differential cortical retention?
% retained in each kidney at 15 or 20 mins
differential renal function
each kidney 45-55%
what is differential renal function
comparing activity in each kidney at 2-3 mins DTPA
or 1.5-2.5 mins MAG3
which kidney is slightly lower than the other?
right
renal calyces and pelvis usually begin filling by
3 mins
blood flow to kidneys is normally seen within ____ of ab. aorta visualization
2-5 secs
activity visualized in renal parenchyma by
1-5 mins
if a patient was dehydrated, what would we see on the renogram?
elevation of excretion slope
increased liver/spleen activity can indicate…
renal failure
allograft
transplant from same species
normal results for renal transplant
flow:
RP bolus to get to transplant at almost the exact time seen in the iliac vessels
normal results for renal transplant
function:
max uptake 3-5 min
bladder by 4-8 min
prompt peak and rapid clearance
normal results for renal transplant
function:
function:
