Contrast Review And Medicines 8.2.24 Flashcards
Why we use contrast?
- Differentiate anatomy
- Differentiate pathology/ abnormalities
- may provide information on function
What is the Path of IV contrast?
- Peripheral vein
- Deep vein
- Right heart
- Pulmonary arterial tree
- Left heart
- Systemic arterial vessels
- Visceral enhancements
- Venous drainage
- Excretion and recirculation
What is Positive contrast?
How does it appear on images?
Bright on CT
- iodinated as very good at absorbing x-rays
- IV administration unless specific indications for oral contrast
What is Negative contrast?
How does it appear on images?
Dark on CT
- Gas eg in CT colonography
- water - sometimes referred to as neutral contrast
What are the differences between high and low Osmolality of contrast agents?
High osmolar - ionic - not used IV anymore
Low osmolar - non-ionic monomer
ISO-osmolar - Non-ionic dimer
What are some of the Risks of giving CT contrast?
= Extravasation - contrast leeks out of cannulated vein
= Allergic type reaction
- previous reaction
- usually quickly after administering
- mild, moderate or severe
= Acute kidney injury
- related to renal function
- eGFR requested prior to contrast
What are the methods of Timing Contrast delivery?
- Timing bolus
- Fluoroscopic timing (bolus tracking)
- fixed timings
- Aterial
-portal venous
- delayed phases
What does MRI contrast contain?
Gadolinium based
- Gadolinium is toxic and can’t be excreted so is bound to other molecules
- linear or macrocyclic chelating agent
How does MRI contrast Work?
= shortening the T1 decay - increases the image brightness in T1W imaging
= shortens T2 - reduces T2 signal, therefore not used in T2w imaging
= too much contrast - T2 properties overwhelm T1 properties and signal is lost
How do we Time the administration of MR contrast?
What are some of the phases they are looking for within organs?
Angiography - blood pool perfusion of the vessel of interest
~Test bonus
~ Bolus tracking
~Time resolved MRA
First-pass organ, perfusion
Early post contrast
Delayed imaging options, e.g. Urography, liver, cardiac
What does PGD stand for and what is it?
Patient group directive -a legal framework, some registered health professionals to supply or administer specific medicines to predefined group of patients without having to see a prescriber.
What are the common Routes of administration?
Oral
IV - syringe or pump
IM
What is Analgesia?
Where does it affect?
Pain relief
No sedated
It can be local or systemic
Systemic = whole body
Local = just a small site
What can Sedation be?
Variable levels
Anxiolytic to general anaesthetic
Anxiolytic is a drug to reduce anxiety
What is the most common Local anaesthetic?
What are they used for?
How are they administered?
Lidocaine - most common
- usually by injection into the skin surface deeper structures
- Often used for biopsy sites
- Interventional line access
- Dental anaesthesia
Can cause be used to treat certain cardiac arrhythmias, so it’s not injected into vessel in this context.
Can be combined with adrenaline or epi to prolong action via vasoconstriction
Would be administered directly by the individual performing the procedure
Many other types of method of administering local anaesthetic, e.g. nerve, blocks, regional blocks topical
What are examples of Systemic analgesia?
Opioids - fentanyl - rapid action, short half life and few side effects
Non-opioids
- NSAIDS
- Paracetamol
- Entonox
What are common Sedatives?
How are they administered?
Benzodiazepines - anxiolytic and amnesiac properties
Most common = midazolam in hospital setting and for uncomfortable procedures
Many oral prescribed options, e.g. diazepam temazepam when only light sedation is required. Occasionally used for anxiety, e.g. MRI claustrophobia
Administered by sedation/medical teams, not responsibility of radiographers
What are the common Anaesthetic drugs?
Who administers them?
Propofol - GA - Infusion and used only by anaesthetic teams
Ketamine - Lots of side effects - only given by dedicated teams
What are the Bowel prep medications?
What effect do they have on the colon?
What effect dot hey have on the images?
Sodium Picosulphate
- picolax
- citrafleet
- citramag
Laxative increases motility of the colon
Ensure clear: of faecal residue prior to colonic investigations, e.g. CT colonography , contrast, enema, or conventional colonography
Positive or contrast is something sometimes used in CT colon to tag vehicle matter, allowing it to be digitally subtracted .
What is Busscopan?
Buscopan - antimuscarinic
Used as an antispasmodic in bowel imaging
US uses glucagon
What are the Side effects of Buscopan?
Blurred vision so wait before driving
Constipation
Dry mouth
Palpitations / increased HR
Urinary retention
How long should pt wait after scan?
30 min
What is Glucagon?
-Has been used as an anti-peristaltic in gi studies
-More in the USA
-Hyperglycaemic action
-Not as effective as Buscopan
-Not as well tollerated as Buscopan
-More expensive than Buscopan
What is Mannitol used for?
What are the effects of mannitol?
Used in all contrast, agent for small, bowel imaging MRI and CT
Distends , the small bow, allowing visualisation of the wall, more effective than water
Similar imaging appearances to water. Neutral contrast agent in CT
Hyperosmolar - draws water into the bowel lumen
Diarrhoea
Bowel Spasms
Flatulence
Many uses in medicine
