RNI common imaging techniques Flashcards
2 methods used for renal RNI
renal cortical imaging
dynamic renal imaging
renal cortical imaging
99mTc dimercaptosuccinic acid (DMSA)
- adult dose is 80M
- dose is scaled down for paeds - minimum of 15 MBq
dynamic renal scanning
99mTc mercaptoacetyltriglycine (MAG3) is mainly used - 100MBq 99mTc diethylenediamine penta-acetic acid (DTPA) also commonly used - 300MBq
- scale down dose for children - minimum dose of 15MBq
indications of static DMSA scan
- recurrent UTI
- horseshoe kidney
- ectopic kidney - grown in the wrong place
- assessment of reflux
renal cortex DMSA adult prep
80MBq is injected 2 hours prior to the scan- to allow effective uptake
at 2-3 hrs it gives the best binding for imaging
- patient must avoid pregnant women and public transport after injection for next 24 hrs
renal cortex DSMA scan paediatric prep
- booked onto children’s ward
- cannulated on ward and dose is administered
- injection is given 2 hrs prior to scan, to allow effective uptake
- 2-3 hours - best binding for imaging
- patient returns back to ward
- radioactive nappies are stored
renal cortex DMSA technique (adults)
- patient sits erect in between the gamma camera heads on rni imaging chair
- Posterior view
- LPO
- RPO
- 300 second images
- patient should avoid movement
renal cortex DSMA scan - paeds
- patient lies on the scanning table with the gamma camera above and below patient
- sponge pad is provided for support and reduce movement
renal cortex DSMA scan - paeds views
- posterior view
- LPO
- RPO
- 300 second images
- patient must avoid movement - can cause blurring
renal cortex DSMA scan - after care adults
- keep hydrated and flush twice after urination
- they can go home as normal, however avoid women and public transport
renal cortex DSMA scan - after care paeds
- paed nappies need storing for 1 week and then disposed off in 14 days in normal waste bin
- keep eating and drinking normally
- if sedation is used, paed must be admitted to children’s ward and monitored - radiation sheet attached to their notes
- cannula is removed and placed in sharp bin if no longer needed
Advantages of DSMA imaging
- relatively low dose
- demonstrates physiology rather than anatomy
- assesses differential uptake/function of renal cortex
disadvantages of DSMA imaging
- does not show anatomy
- invasive and paeds may require sedation
- more costly if child is admitted onto the ward
Dynamic renogram
assesses renal function and excretion
Dynamic renogram indications
- evaluation of obstruction
- assessment of differential renal functions
- assessment of perfusion
- renal trauma assessment
- diagnosis of renal artery stenosis
Dynamic renogram patient prep
- patient well hydrated prior to scan
- document all medications that can affect study e.g. blood pressure medication
- ## they must empty bladder before scan
Dynamic renogram patient positioning
- either supine or erect with gamma camera posterior - so that kidneys are closest to the camera
- make sure patient is cannulated and is patent (flushed with saline)
Dynamic renogram technique
- inject patient
- imaging starts immediately
- 1-3 seconds per frame for 60 seconds - assess renal perfusion
- measure syringe post injection to calculate absolute dose
advantages of MAG3 imaging
- relatively low dose
- demonstrates physiology - assesses differential function
- can distinguish between calculi and physiological obstruction
- doesn’t require contrast
- can also assess reflux
Disadvantages of MAG3 imaging
- doesnt show anatomy
- invasive - may require sedation in paeds - can alterresults
- may need rebooking, if child is non-compliant
RNI Imaging of the endocrine
- can assess parathyroids, thyroid and adrenal glands
reasons to scan thyroid glands
- assess thyroid function - usually after abnormal blood test
- assess treatment post ablation dose
if thyroid carcinoma is suspected, which radionuclide is preferred
iodine 131
Thyroid RNI - patient prep
- patients should not have CM in previous week to scan
- they must discontinue their thyroid interfering medication
- nil by mouth 4 hrs before scan
- patient should wear loose clothing
- empty bladder before scn
