Central Nervous System GW

Question 1

BBB imaging is most useful for these suspected pathologies

Answer 1

1. Primary or metastatic disease (glioma, meningioma
2. Intracranial inflammatory disease (abscess, encephalitis)
3. Cerebrovascular disease (hemorrhage, occlusion, hemangioma)
4. Head trauma complications (subdural hematoma, brain death)

Question 2

BBB imaging RPs

Answer 2

Tc99m Pertechnetate
Tc99m pentetate DTPA

15-30 mCi

Question 3

What is the least desired RP for BBB imaging and why

Answer 3

Tc99m pertechnetate because it uptakes in choroid plexus and you have to use a blocking agent of potassium perchlorate

Question 4

Which RP for BBB imaging is most desired and why

Answer 4

Tc99m DTPA because it is rapidly cleared by kidneys - lower exposure to patient
can image sooner
no blocking agent required

Question 5

How much potassium perchlorate must be administered for imaging BBB with pertechnetate

Answer 5

0.2-1 g oral

Question 6

How is BBB imaging typically acquired

Answer 6

Planar, 3 phase, LEAP/converging collimator

Question 7

How is pt positioned for BBB imaging

Answer 7

Flow - upright with head and nose touching collimator

Blood pool and delays - ANT, POST, LATs with lead on face, and vertex with lead on shoulders

Question 8

Normal BBB imaging findings

Answer 8

In 6 secs you’ll see right and left carotid arteries, and anterior cerebral artery

SSS showing means arterial blood is entering venous system

Question 9

Abnormal findings BBB imaging

Answer 9

Disruption of BBB will show increased localization of RP in the area of pathology

Brain death flow will show tracer in carotids but a complete absence in middle and anterior cerebral arteries due to increased intra cranial pressure

Question 10

What is brain perfusion imaging used for

Answer 10

Functional abnormalities
1. Cerebrovascular disease (stroke, TIAs)
2. Dementia
3. Psychiatric disorders
4. Seizure disorders
5. Head trauma (cerebral brain death)

Question 11

How is brain perfusion imaging performed

Answer 11

SPECT, except brain death is planar

Question 12

How is brain death imaging performed

Answer 12

Planar

Question 13

Brain perfusion RPs

Answer 13

99mTc exametazime HMPAO
99mTc bicisate ECD

10-20 mCi

Question 14

Pt prep for brain perfusion imaging

Answer 14

Quiet, dimly lit room, unstimulated

Question 15

Which RPs cross the BBB

Answer 15

Tc99m exametazime HMPAO
Tc99m bicisate ECD

And then becomes fixed in the brain cells - can image up to 6 hours

Question 16

What RP must you use a fresh generator eluate <2 hours old

Answer 16

99mTc exametazime HMPAO

Question 17

Maximum imaging time for brain perfusion agents

Answer 17

Can image up to 6 hours after injection because HMPAO and ECD become fixed in brain cell

Question 18

Normal tracer distribution in brain perfusion imaging

Answer 18

Symmetric in both hemispheres. Grey matter will show more than white matter (more blood flow). White matter may have no uptake

Question 19

Abnormal distribution in brain perfusion imaging

Answer 19

Acute cerebral infarct - cold spot.
Alzheimer’s - decreased perfusion in parietal, temporal, and frontal lobes.
Multifarct dementia - multiple areas of decreased uptake.
Schizophrenia - decreased perfusion to frontal lobes.
Depression - decreased uptake over entire cerebral cortex.
Manic - greatly increased perfusion overall.
Active seizure - intense focal uptake.

Question 20

Interventional drug for brain perfusion

Answer 20

Acetazolamode “diamox” (1g) - induces cerebral vasodilation

RP is injected 25 mins later

Question 21

BBB imaging/brain perfusion is also called

Answer 21

Cerebral angiography

Question 22

Planar brain death RP

Answer 22

Tc99m exametazime HMPAO usually
- can obtain images 1-3 hours later
-or can take flow study

Tc99m ECD

Can use 99mTc DTPA - less desirable

Question 23

Where is CSF produced

Answer 23

Choroid plexus

Question 24

What does CSF do

Answer 24

Shock absorber for the CNS

Question 25

Cisternography indications

Answer 25

Diagnosis of normal pressure hydrocephalus, CSF leaks, ventricular shunt patency

Question 26

Cisternography RP

Answer 26

In111 pentetate DTPA
0.5 mCi

T 1/2 2.8 days
Excreted renally

Question 27

Where is cisternography RP injected

Answer 27

Intrathecally in subarachnoid space, between 3rd and 4th lumbar vertebrae

Question 28

Normal cisternography didtribution

Answer 28

4-6 hrs: Activity seen in spinal cord ascending to basal cisterns

24 hrs: tracer clearance from the basal cisterns, activity seen in subarachnoid space surrounding cerebral hemispheres, interhemispheric cisterns, and SSS

Question 29

Abnormal cisternography

Answer 29

NPH: visualization of lateral ventricles at any point and delay of activity in SSS

CSF leak: leak activity and activity on swabs

Question 30

Ventricular shunt patency imaging RP and route

Answer 30

99mTc pertechnetate - not approved for intrathecal use, we can use it here bc it’s going into shunt
In111 pentetate - less desired

Directly into shunt reservoir

Question 31

Dopamine transporter imaging RP

Answer 31

I123 ioflupane

3-5mCi

Question 32

Dopamine transporter imagine indications

Answer 32

Detects degeneration of the dopaminergic nigrotriatal pathway
- differentiated pts with essential tremor from Parkinsonism syndromes

Question 33

Drug contraindications for DatScan

Answer 33

Cocaine, -phetamines, stimulants, ephedrine, bupropion, fentanyl, anesthetics (ketamine), SSRIs

*Antiparkinsonian drugs do not interfere

Question 34

Acquisition type for datscan

Answer 34

SPECT

3-6 hrs after injection

Question 35

Normal datscan findings

Answer 35

Comma sign

• the head of the caudate nucleus and putamen

Question 36

Abnormal datscan findings

Answer 36

Period sign (incomplete comma)

Question 37

Another name for normal pressure hydrocephalus

Answer 37

Communicating hydrocephalus