Central Nervous System Procedures Board Practice Questions

What forms the blood–brain barrier?

Tight junctions in brain capillary walls

A technologist needs an agent that will show only blood flowing THROUGH the head and stay out of normal brain tissue. Which group fits?

Tc-99m DTPA, pertechnetate and glucoheptonate

A student asks why Tc-99m HMPAO stays in the brain while Tc-99m DTPA does not. What is the best answer?

HMPAO is lipophilic, crosses the BBB and is trapped

On delayed planar images with Tc-99m DTPA, a focal hot spot appears inside the brain. What does it indicate?

A disrupted blood–brain barrier at that site

Which of these processes would NOT be expected to show as a hot spot on a planar BBB study?

Essential tremor

A trauma patient's delayed planar DTPA images show a crescent of activity along the inner skull. What is the most likely finding?

Subdural hematoma

A tech reviews delayed planar images from a patient with a healthy blood–brain barrier injected with Tc-99m DTPA. What should the images look like?

A scalp, face and sinus rim with an empty-looking brain

A tech watches a cerebral flow study in real time. About when should activity appear symmetrically in both carotids?

About 6 seconds

On a radionuclide cerebral angiogram, which finding marks the start of the venous phase?

Tracer appearing in the superior sagittal sinus

What is the normal 'trident' on a cerebral flow study?

The anterior cerebral artery with an MCA on each side

For the planar cerebral flow study, how is the patient best positioned?

Anterior, upright, forehead and nose on the collimator, neck included

A flow study shows apparently asymmetric carotid flow, but the patient's neck was rotated during acquisition. What is the likely explanation?

Head rotation can create false asymmetric flow

A tech is setting up the dynamic acquisition for a planar cerebral flow study. What framing should be used?

1–3 second frames for 30–60 seconds

When are POSTERIOR cerebral flow views recommended (for example, a 6-year-old with a suspected cerebellar lesion)?

Suspected posterior fossa disease and in children

When is the blood-pool image taken in a planar BBB study?

A 60-second static within 5–10 minutes after the flow

A tech has just finished the flow and blood-pool images on a planar BBB study. When should the delayed statics be acquired?

30 minutes to 3 hours after injection

For delayed planar BBB statics, how are the counts set?

Anterior for 500k–1M counts; other views for the same time

Which delayed planar BBB view requires a lead cape over the patient's shoulders?

Vertex

A tech is choosing a collimator for a planar cerebral flow and BBB study. Which is listed?

Low-energy all-purpose (LEAP) or converging

A physician orders a planar brain flow study with Tc-99m DTPA for an adult. What activity range should be drawn?

15–30 mCi IV bolus

A technologist is asked to perform a planar brain study with Tc-99m pertechnetate. What must be given first?

Potassium perchlorate 0.2–1.0 g orally

Why is perchlorate given before Tc-99m pertechnetate brain imaging?

To keep the choroid plexus from looking like a lesion

Besides the choroid plexus, which organs does potassium perchlorate also block from trapping pertechnetate?

Thyroid, salivary glands and stomach

A radiologist asks why the department uses Tc-99m DTPA rather than pertechnetate for planar brain imaging. What is the best answer?

Fast renal clearance and no choroid plexus uptake

How does Tc-99m DTPA localize during the flow phase of a cerebral angiogram?

Compartmental localization in the blood pool

What is the critical organ for IV Tc-99m DTPA brain imaging?

Kidneys / bladder wall

What is the critical organ for IV Tc-99m pertechnetate brain imaging?

Thyroid / stomach (upper large intestine)

Which statement about Tc-99m DTPA, glucoheptonate and pertechnetate in perfusion SPECT is correct?

None of them is used, because none crosses an intact BBB

A Tc-99m DTPA brain kit is prepared. How is it labeled?

Kit + Tc-99m pertechnetate with stannous reduction

A tech is preparing an adult for a planar brain flow study. Which prep step is listed?

Remove glasses and hair clips and tape the head

A patient with a suspected AV malformation is sent for a planar BBB study. Which indication category does this fall under?

Cerebrovascular disease

Which agent is described as the LEAST desirable for planar brain imaging?

Tc-99m pertechnetate

What physiologic process causes the absence of cerebral flow in brain death?

Intracranial pressure exceeds the pressure driving blood in

What is the classic appearance of brain death on perfusion-agent imaging?

Hollow skull: empty cranium, scalp and face still seen

Faint uptake is seen in the cerebellum but none in the cerebrum on a Tc-99m HMPAO brain death study. How is this read?

Not consistent with brain death

A tech reviews a Tc-99m DTPA flow study ordered to confirm brain death. Which finding supports the diagnosis?

Carotids visible but no flow into the ACAs and MCAs

Why do the protocol book, Bolus and the current guideline prefer HMPAO or ECD over DTPA for brain death?

They're trapped, so a perfect bolus isn't essential

A tech has a poor IV and is worried the bolus will be slow. For which brain death agent would that matter MOST?

Tc-99m DTPA

An adult brain death study is ordered with Tc-99m HMPAO. What activity does the blue book list?

10 mCi (range 10–30 mCi)

A tech is about to inject Tc-99m HMPAO for a brain death study. What special item must be on the line?

A 0.22-µm filter

A 20-kg child needs a perfusion-agent brain death study. What dosing rule applies?

0.3 mCi/kg, minimum 5 mCi

A comatose patient needs a brain death study. Who gives consent?

A surrogate decision-maker

Which two conditions are listed as confounders that can falsely suggest no cerebral flow?

Barbiturates and hypothermia

A brain death patient is on a pentobarbital coma. How should the technologist handle this?

Note it, because barbiturates are a confounder

Which ventilation change is a concern before a brain death study?

Hyperventilation, which changes cerebral blood flow

The ICU nurse offers the line running norepinephrine for the brain death injection. What should the technologist do?

Use a vein or line not used for pressors or transfusions

What patient prep is required for a brain death study?

None; keep BP stable and ventilation normal

A tech starts the camera at the moment of a brain death injection. What framing does the blue book give?

3 seconds per frame for 1–2 minutes

A tech is setting up the static images for a brain death study. What counts and matrix are used?

500,000–1,000,000 counts, 128 × 128

Which views are acquired for brain death statics?

Anterior plus a lateral; posterior optional

Why can a perfusion-agent brain death study be done portably in the ICU?

No flow study is needed, so it can be injected in the room

About when are HMPAO brain death statics typically acquired according to Bolus?

1–3 hours after injection

What is the classic purpose of an elastic band around the head during a brain death study?

To reduce scalp flow so it isn't mistaken for brain flow

A resident asks which brain death agent needs an elastic band around the head, per Mantel. What is the answer?

Tc-99m DTPA only

A tech trained on the old protocol reaches for a scalp tourniquet before an HMPAO brain death study. What does the 2025 SNMMI/EANM guideline say?

It is no longer recommended

What precaution does the blue book give for the head tourniquet?

Use caution in head trauma; it may worsen the injury

A brain death study shows increased nasal activity (the 'hot nose' sign). How should it influence the reading under the current guideline?

Too unreliable to influence interpretation

What causes the 'hot nose' sign on a brain death study?

External carotid shunting of blood to the face

A brain death study shows faint residual perfusion. What does the guide say may happen next?

It may be repeated in 1–2 days if the patient worsens

A patient's brain death study is positive. Who makes the brain death determination?

The clinician, using exam and ancillary data

An HMPAO brain death study shows no cerebral uptake. Which other structure must also show NO uptake for the study to support brain death?

Cerebellum

Which collimator setting is used for a brain death study in a child?

Converging collimator or zoom

Which artery supplies the scalp and face activity seen in the hollow skull sign?

External carotid

What SPECT parameters are listed for an optional brain death SPECT?

360°, 128 × 128, 120 projections at 30 s

When should optional brain death SPECT be skipped?

If the patient is unstable or life-support equipment prevents it

During a brain death flow study, faint activity is seen in the superior sagittal sinus with no arterial filling. How should this be interpreted?

Faint sinus activity can occur; what matters is no arterial or brain flow

A pharmacy label reads 'exametazime.' Which brain agent is this?

Tc-99m HMPAO (Ceretec)

A pharmacy label reads 'bicisate.' Which brain agent is this?

Tc-99m ECD (Neurolite)

A tech is asked to prepare a Tc-99m HMPAO kit. Which brand name should be pulled from the shelf?

Ceretec

A tech is asked to prepare a Tc-99m ECD kit. Which brand name should be pulled from the shelf?

Neurolite

Inside the brain cell, what converts HMPAO into its trapped hydrophilic form?

Glutathione

Inside the brain cell, what converts ECD into its trapped hydrophilic form?

Esterases

Why can a perfusion SPECT be imaged an hour or more after injection and still show the injection-time flow?

The tracer is fixed in the cells and barely redistributes

How does HMPAO or ECD enter the brain?

Passive diffusion across the BBB in proportion to blood flow

A tech reconstitutes unstabilized HMPAO. When may it be injected?

Between 10 and 30 minutes

A tech adds the stabilizer to an HMPAO kit. How long after reconstitution can it be used?

Within 4 hours

A tech reconstitutes a Tc-99m ECD kit for an outpatient. What is its use window?

No sooner than 10 minutes, no later than 6 hours

What stabilizer is used to extend the HMPAO shelf life to 4 hours?

Methylene blue/cobalt stabilizer

A tech plans to make an HMPAO kit from a generator that was last eluted 30 hours ago. Which requirement applies?

Use eluate from a generator eluted within the past 24 h

What does Bolus say about the pertechnetate eluate age for HMPAO?

Fresh eluate under 2 hours old is best

Which perfusion agent must be injected through a 0.22-µm filter?

Tc-99m HMPAO

A patient was injected with HMPAO for perfusion SPECT. When should imaging start per the blue book?

90 minutes after injection

A patient was injected with ECD for a routine perfusion SPECT. When should imaging start per the blue book?

45 minutes after injection

Why can ECD be imaged sooner than HMPAO?

Faster blood clearance gives better target-to-background

Mantel Q14 asks about ECD's advantages. Which answer fits?

Longer shelf life, faster blood clearance and better contrast

An adult is scheduled for perfusion SPECT with HMPAO. What dose does the blue book list?

10 mCi (range 10–30 mCi)

A child is scheduled for HMPAO perfusion SPECT. Which dosing rule applies?

0.3 mCi/kg, minimum 5 mCi, maximum 20 mCi

A tech is preparing a patient for perfusion SPECT. How far ahead of the injection should the IV be placed?

At least 10 minutes

A patient is chatting and reading a magazine in a bright waiting room when HMPAO is injected. What is the risk?

Language or visual cortex lights up and can hide or mimic disease

For how long should the patient rest in a quiet, dim room before HMPAO or ECD injection?

20–30 minutes

Should the patient's eyes be open or closed at the time of perfusion tracer injection?

Open

For how long after a perfusion tracer injection should there be no interaction with the patient?

5 minutes

A patient calls the day before perfusion SPECT asking what to avoid. What should be stopped 24 hours before?

Caffeine, alcohol and drugs that alter cerebral blood flow

A patient arrives for perfusion SPECT and says she smoked a cigarette this morning. What does the prep require?

Prep not met: no smoking is allowed on the study day

An agitated dementia patient needs sedation for perfusion SPECT. When can it be given?

At least 5 minutes after the tracer injection

Why doesn't sedation given after HMPAO injection spoil the perfusion picture?

The tracer is already fixed, so later flow changes don't matter

A sedated patient finishes perfusion SPECT. What discharge instruction applies?

Someone else must drive the patient home

When should the patient void after perfusion tracer injection to reduce dose?

Within 2 hours

A student asks why gray matter looks so much brighter than white matter on HMPAO SPECT. How do their blood flows compare?

Gray matter has about 4× the flow

On a normal HMPAO SPECT, which structures appear brightest?

Cortex, basal ganglia and thalamus