CNS Test Out Personal

a patient has a Tc heart study and a ceretec study in the same day, which do you do first

ask the physicians which they would prefer, there isnt any concern for cross-organ uptake so its more of a preference for the radiologist based on urgency. Also the lexiscan might have an effect 

what is the image acquisition of one brain study? Datscan

126×126 SPECT study

25-40 sec/stop→ step and shoot

>150 million counts

imaging for roughly 30-45 min

when processing a brain study, what are you looking for? whats the difference between MIP images and the slices

the purpose of the MIP is to give you a quick overview of the image- see alignment, distribution, check proper reconstruction

the slices will give you actual diagnostic interpretation of the image

where are two places CSF is shunted to 

1. peritoneal cavity

2. heart (RA)

what is the image acquisition for a brain death? (HMPAO)

flow study 1-2 sec/frame for 60 sec then a blood pool for 300k-500k counts; LEHR collimator

when are CSF pictures taken? (cisternography)

image at 2, 6, 24, 48

ictal seizure imaging

injecting when the seizure starts→ looking for hot spots due to high metabolic activity

interictal seizure imaging

injecting when the seizure ends→ looking for cold spots due to hypometabolic activity

where is the isotope injected for a CSF study?

lumbar puncture between L3-L4

what are pledgets and why are they used

they are little cotton balls placed in either the nose or ears when a patient has a suspected CSF leak (3-4x activity than plasma background is positive)

what are 3 clinical indications for a CSF study

• CSF leak

• Assessment of shunt patency

• assess pathway of CSF drainage

advantage of Tc-99m HMPAO

has a slower wash out= can inject and wait to image; good for epilepsy

Disadvantage of HMPAO

poorer contrast between white and grey matter

Advantage of Tc-ECD

• longer shelf life

• better contrast between white and grey matter

Disadvantage of ECD

• not as great of a first pass extraction compared to HMPAO

• faster wash out 

Advantage of TC-DTPA

cheap

Disadvantage of TC-DTPA

does not cross the blood brain barrier