RADIONUCLIDE IMAGING TECHNIQUE: RENAL & ENDOCRINE Flashcards
1
Q
WHAT ARE THE TWO METHODS OF RENAL IMAGING?
A
- renal cortical imaging
2. dynamic renal imaging
2
Q
WHAT IS THE RADIONUCLIDE USED FOR RENAL CORTICAL IMAGING?
A
- 99mTc dimercaptosuccinic acid (DMSA).
- Adult dose of 80 MBq (ARSAC)
- Scaling down dose for paediatrics - A minimum dose of 15 MBq is recommended (the dose is calculated as per age and weight)
3
Q
WHAT IS THE RADIONUCLIDE USED FOR DYNAMIC RENAL IMAGING?
A
- 99mTc mercaptoacetyltriglycine (MAG3) is the most widely used agent - 100 MBq (Has to be boiled first and then cooled before administration for effective labelling)
- 99mTc diethylenediamine penta-acetic acid (DTPA) is also widely used - 300 MBq (get more noise though on the image due to poorer soft tissue clearance)
- Doses scaled down for children – minimum dose 15MBq
- +/- Furosemide (IV)
4
Q
WHAT ARE THE INDICATION FOR RENAL CORTEX STATIC DMSA SCAN?
A
- Assessment of individual and relative (differential) renal function.
- Recurrent UTI (paeds)
- Assessment of reflux
- Cortical scarring (Gold standard test in paediatrics)
- Horseshoe kidney
- Ectopic kidney
- transplant assessment post-surgery (although 99mTc-MAG3 renogram gives more information regarding function)
- check Response to antibiotics therapy post cortical scarring – follow-up.
5
Q
WHAT IS THE PATIENT PREPARATION (ADULT) FOR RENAL CORTEX STATIC DMSA SCAN?
A
- For adults there is no specific preparation and they can eat and drink normally prior to the scan.
- 80MBq of 99mTc-DMSA
- Injection is given 2 hours prior to the scan to allow effective uptake (DMSA binds to the proximal convoluted tubule of the kidney for a few hours before being excreted in urine). 2-3 hours gives best binding for imaging.
- Residual syringe dose MUST be measured post injection so that absolute dose is calculated.
Patients can leave the department and hospital during this time avoiding pregnant women and public transport. - If they stay in the hospital then they should use the departmental toilet (as their urine will be radioactive) and ALL patients should void their bladder prior to their scan.
6
Q
WHAT IS THE ADULT TECHNIQUE FOR RENAL CORTEX STATIC DMSA SCAN?
A
- Patients can sit erect in-between the gamma () camera heads on an RNI imaging chair (This swivels in all directions for ease of positioning)
- Static Images are acquired using a LEHR collimator:
- Posterior view
- Anterior view (only if double-headed as not needed for results – why?)
- LPO
- RPO - 300 second images
- +/- SPECT views
- The patient must keep still for each view to avoid movement blurring/image distortion
7
Q
WHAT IS THE PATIENT PREPARATION (PAEDIATRIC) FOR RENAL CORTEX STATIC DMSA SCAN?
A
- For children it is best to book them onto the paediatric ward (and do a paed list for the session).
- They are cannulated on the ward and then the dose is either administered on the ward or in the department (but not in the scanning room)
- The dose is calculated from weight and age following ARSAC guidance calculations
- Injection is given 2 hours prior to the scan to allow effective uptake (DMSA binds to the proximal convoluted tubule of the kidney for a few hours before being excreted in urine). 2-3 hours gives best binding for imaging.
- Patients return to the ward following the injection (if they have come down) – this is where your play specialists can really help both during this time and when they return to for their scan.
- Will need to store radioactive nappies (although dose is very low) on the ward or return to RNI for storage.
- If a feed is due prior to the scan then this should be delayed until just before they come down to the department (this then makes them fall asleep usually and relaxes them).
- Sedation should be avoided if possible - does not always work + extra monitoring
8
Q
WHAT IS THE PAEDIATRIC TECHNIQUE FOR RENAL CORTEX STATIC DMSA SCAN?
A
- Patients lie on the scanning table with the -camera above and below the patient. The patient can be placed in a sponge support to help avoid movement (a supportive hand can be placed on the child’s tummy) and hopefully they are asleep if they are young babies/toddlers)
- Static Images are acquired using a LEHR collimator:
- Posterior view
- Anterior view (only if double-headed as not needed for results) – if the child is fractious then do not take this view.
- LPO
- RPO - 300-second images
- +/- SPECT views (not often done on paeds do to time and compliance)
- The patient must keep still for each view to avoid movement blurring/image distortion – so distraction techniques (such as DVD’s, music, toys can be used +/- a play specialist)
9
Q
WHAT IS THE POST-PROCEDURAL CARE FOR ADULTS IN STATIC DMCA SCAN?
A
- Can go home directly and just told to avoid pregnant women and public transport for 24 hours post procedure.
- Keep drinking plenty of fluids and eat normally (flush chain twice after urination)
10
Q
WHAT IS THE POST-PROCEDURAL CARE FOR PAEDIATRICS IN STATIC DMCA SCAN?
A
- If not required then remove the cannula and place in a radioactive sharps bin for 99mTc
- Paed nappies need storing for 1 week and then can be disposed off in 14 days in normal waste (so you need to advise the parents of this).
- Keep drinking and eating normally.
- If sedation is used then the paed must be admitted onto the children’s ward under observation – radiation sheet MUST be attached to the patient notes and the child placed in a side room. Risks very minimal as doses are so low.
11
Q
WHAT ARE SOME OF THE THE ABNORMALITIES FROM A RENAL CORTEX STATIC SCAN?
A
- significantly more uptake of radiotracer in one kidney than the other showing that one kidney is not functioning properly.
- multicystic kidney ( due to UTI) - enlargement of a kidney with multiple cysts leading to less uptake of radiotracer
- horseshoe kidney (smiley face) - obstruction of the ureter due to building up of calculi
12
Q
WHAT ARE THE ADVANTAGES OF RENAL STATIC DMSA SCANNING?
A
- Relatively low dose (especially for paeds)
- Demonstrates physiology rather than anatomy – so shows scarring where other modalities would show normal anatomy (so it is more sensitive than ultrasound, urodynamics and CT).
- Assesses differential uptake/function of the renal cortex
- Useful for follow-up after Abx treatment to assess recovery
13
Q
WHAT ARE THE DISADVANTAGES OF RENAL STATIC DMSA SCANNING?
A
- Doesn’t show the anatomy
- Invasive (unlike ultrasound) and may require sedation in paeds.
- If the dose tissues or the child is non-compliant then the exam may have to be re-booked (more dose)
- More costly if the child has to be admitted onto the ward.
14
Q
WHAT ARE SOME OF THE INDICATIONS TO IN ORDER TO TO DO A DYNAMIC RENAL IMAGING? (MAG3)
A
- Evaluation of obstruction.
- Assessment of differential renal function
- Assessment of perfusion of acute native or Tx kidney
- Demonstration of Vesico-ureteric reflux
- Assessment of renal Tx kidney
- Assessment of renal trauma
- Diagnosis of renal artery stenosis (RAS)
- Contrast allergies/contraindications
- All paediatric patients.
15
Q
WHAT IS THE PATIENT PREPARATION IN ORDER TO DO A DYNAMIC RENAL IMAGING?
A
- Patients should be well hydrated prior to the study
- Excretion and washout can be delayed by dehydration, simulating obstruction - Document all medications that may affect the study
- Diuretics; blood pressure medication - Make sure they void their bladder prior to injecting the patient (Very Important!)
Patient positioning – either supine or erect with the -camera posterior, so that kidneys are closest to the -camera – centre the patient to the camera head by marking shoulders and pelvis (both sides) with a cobalt pen (57Co) - Check if the patient has had lymph removal surgery at all.
- Make sure the patient is cannulated and that it is patent (flush with saline and check for extravasation). If necessary re-position in the other arm.
