SP7:Central Nervous System Scintigraphy

Question 1

The venous phase of a cerebral blood flow study is signaled by:
(a)Visualization of the jugular veins

(b) Appearance of the radiopharmaceutical in the superior sagittal sinus
(c) Disappearance of radiopharmaceutical from the carotid arteries
(d) Appearance of radiopharmaceutical in the middle cerebral arteries

Answer 1

(b) The superior sagittal sinus is a dural venous sinus located in the midline. Tracer usually appears thereafter about 15 s signifying the venous phase of the blood flow study. In some cases, low-level activity in the sagittal sinus from the scalp can be mistaken for venous flow.

Question 2

The localization of 99mTc HMPAO is related to:
(a)A breakdown of the blood–brain barrier

(b) Cerebral blood flow
(c) Glucose metabolism
(d) Distribution of neuroreceptors

Answer 2

(b) Exametazime enters the brain via the cerebral blood flow. It then crosses the blood–brain barrier and is metabolized to a form that cannot diffuse out of the brain.

Question 3

CSF is made mostly of:
(a)Protein

(b) Water
(c) Glucose
(d) Blood

Answer 3

(b) Cerebrospinal fluid, which is produced in the choroid plexus and serves to cushion the brain and spinal cord, is about 99% water. It also contains a small percentage of plasma proteins.

Question 4

The function of cerebrospinal fluid is to:
(a)Protect the brain and spinal cord against shock.

(b) Filter plasma.
(c) Produce neurotransmitters.
(d) All of the above.

Answer 4

(a) Cerebrospinal fluid acts as a shock absorber for the brain and spinal cord. It occupies the subarachnoid space and the cord’s central canal.

Question 5

When positioning for a radionuclide angiogram, the patient should be positioned:
(a)Posteriorly

(b) Anteriorly
(c) With as much facial activity as possible excluded
(d) None of the above

Answer 5

(b) Images are ideally obtained anteriorly, with the patient upright whenever feasible. The neck should be included, and the top of the head should not be outside the FOV. However, in many cases, the condition of the patient makes this positioning impossible.

Question 6

Exametazime is also known as:
(a)DTPA

(b) MAG3
(c) HMPAO
(d) ECD

Answer 6

(c) HMPAO is hexamethyl propylene amine oxime and is also known as exametazime. ECD means ethylene l-cysteinate dimer and is also known as bicisate. MAG3 is mertiatide, and DTPA is diethylenetriaminepentaacetic acid.

Question 7

Bicisate is also known as:
(a)DTPA

(b) MAG3
(c) HMPAO
(d) ECD

Answer 7

(d) HMPAO is hexamethyl propylene amine oxime and is also known as exametazime. ECD means ethylene l-cysteinate dimer and is also known as bicisate. MAG3 is mertiatide, and DTPA is diethylenetriaminepentaacetic acid.

Question 8

CSF dynamics are studies following administration of 111In DTPA:
(a)Via intravenous injection

(b) Via intraperitoneal injection
(c) Via intrathecal injection
(d) Via intradermal injection

Answer 8

(c) 111In DTPA (or other radiopharmaceuticals) is injected by lumbar puncture into the aubarachnoid space, the intrathecal space surrounding the spinal cord.

Question 9

The dose which would commonly be used for a radionuclide angiogram with 99mTc DTPA is:
(a)5 mCi

(b) 10 mCi
(c) 20 mCi
(d) 25 mCi

Answer 9

(c) The Society of Nuclear Medicine (Feb 2003) recommends 15-20 mCi of 99mTc DTPA for brain death scintigraphy. Ten to 30 mCi is recommended for 99mTc HMPAO and 99mTc ECD.

Question 10

Which of the following is true regarding injection of the radiopharmaceuticals for SPECT brain imaging?
(a)Lights should be dimmed during injection

(b) The patient should be encouraged to read or watch TV during injection to take his or her mind off any pain.
(c) Family members should be allowed to talk to the patient during injection.
(d) Injection should be made immediately after venous puncture to avoid clot formation.

Answer 10

(a) Since various stimuli and cognitive functions will affect regional blood flow, the venous access should be achieved a few minutes before injection. The patient should then wait in an atmosphere of minimal stimuli (light, noise, pain, etc.).

Question 11

Which dose could be used for 99mTc ECD or 99mTc HMPAO for SPECT brain imaging?
(a)2-5 mCi

(b) 5-7 mCi
(c) 7-10 mCi
(d) 20 mCi

Answer 11

(d) 15 to 30 mCi of 99mTc HMPAO or 99mTc ECD is injected for SPECT brain imaging.

Question 12

Ictal SPECT and PET studies require an injection of radiopharmaceutical:
(a)During a seizure

(b) Immediately after a seizure
(c) Between seizures
(d) Both (a) and (b)

Answer 12

(d) Ictal examinations are performed by injecting the radiopharmaceutical during or within 30 s following a seizure. Interictal examinations are those performed between seizures.

Question 13

HMPAO and ECD are lipophilic agents that do not significantly redistribute in the brain.
(a)True

(b)False

Answer 13

(a) Because HMPAO and ECD do not restistribute in the brain for at least an hour following intravenous injection, they are particularly useful for ictal studies, allowing an image of blood flow during seizure activity.

Question 14

Advantages of using ECD over HMPAO for SPECT imaging of the brain include:
(a)Can be injected up to 6 h after preparation

(b) More rapid clearance from the bloodstream
(c) Better target to background ratio
(d) All of the above
(e) None of the above

Answer 14

(d) HMPAO should be used within 4 h after kit preparation. ECD can be injected up to 6 h after labeling and clears more quickly from the blood. This rapid clearance results in increased target to background.

Question 15

White matter has about four times greater blood flow than gray matter:
(a)True

(b)False

Answer 15

(b) Gray matter has much greater blood flow than white matter. For this reason, gray matter will have greater activity than white matter when performing these examinations with HMPAO or ECD.

Question 16

Planar images of the brain using 99mTc DTPA are obtained:
(a)Immediately after the dynamic exam

(b) 30 min after injection
(c) 1 h after injection
(d) 1.5 h after injection

Answer 16

(a) A dynamic study is usually obtained immediately following injection, and further imaging may be carried out at any time up to 2 h after injection> If brain-specific agents are used, images may be obtained after a delay of at least 20 min.

Question 17

The purpose of placing an elastic band around a patient’s head just above the orbits during a radionuclide angiogram is:
(a)To decrease the activity from the orbits

(b) To increase intracranial pressure
(c) To decrease blood supply to small scalp vessels
(d) To immobilize the patient

Answer 17

(c) When a radionuclide angiogram is used to confirm brain death, it may be difficult to differentiate scalp perfusion from intercerebral blood flow. An elastic band situated above the orbits can reduce the flow to scalp vessels.

Question 18

The images obtained with PET study using 18FDG can best be described as:
(a)Anatomical

(b) Perfusion
(c) Metabolic
(d) Dynamic

Answer 18

(c) Metabolic refers to the building up to substances (anabolism) and the breaking down of substances (catabolism). FDG is a glucose analog and therefore is metabolized initially in the same way that glucose is. Unlike glucose, it is not further metabolized after localizing in the brain substance (because it is phosphorylated) and is therefore a useful imaging agent.

Question 19

In a Diamox challenge study, vascular disease will appear as decreased perfusion after the use of Diamox.
(a)True

(b)False

Answer 19

(a) In areas of normal perfusion, blood flow increases by three to four times following the administration of Diamox, or acetazolamide, which causes vasodilatation. In patients with decreased regional perfusion, the Diamox challenge study may show a perfusion increase. About half of patients will experience side effects, and so all patients should be carefully monitored, although symptoms (lightheadedness, facial flushing and numbness, and numbness in the fingers) usually resolve themselves in about 15 min.

Question 20

The injection for a CSF shunt patency study is:
(a)Intravenous

(b) Subcutaneous
(c) Intrathecal
(d) Into the shunt reservoir or tubing

Answer 20

(d) In a shunt patency study, the radiopharmaceutical is administered directly into the shunt reservoir or the tubing. Activity is then followed to diagnose a malfunction of the shunt. It is necessary to understand the particular type of shunt and its path to diagnose obstruction.

Question 21

Shunts which divert the flow of CSF are often used to treat:
(a)Communicating hydrocephalus

(b) Noncommunicating hydrocephalus
(c) CSF leak
(d) All of the above
(e) (a) and (b) only

Answer 21

(e) Communicating hydrocephalus results when CSF resorption is faulty. Noncommunicating hydrocephalus is caused by obstruction of CSF flow. Shunts may be used to treat communicating hydrocephalus. CSF leaks may result from hydrocephalus (among many other things), but shunts are not used to treat the leak.

Question 22

Which of the following agents will cross a intact blood-brain barrier?
(a)99mTc DTPA

(b) 99mTc GH
(c) 99mTc pertechnetate
(d) 99mTc HMPAO

Answer 22

(d) 99mTc HMPAO, or exametazime, is a lipophilic radiopharmaceutical. It crosses the blood-brain and then is metabolized to another form which does not diffuse out of the brain. The other choices only cross a compromised blood-brain barrier.

Question 23

Which radiopharmaceutical is not commonly used for brain perfusion imaging with SPECT?
(a)99mTc DTPA

(b) 99mTc HMPAO
(c) 99mTc ECD

Answer 23

(a) 99mTc DTPA does not cross the blood-brain barrier and is useful for radionuclide cerebral angiograms. 99mTc HMPAO and 99mTc ECD are used for SPECT studies of brain perfusion.

Question 24

A technologist neglects to give a patient potassium perchlorate before injection with 20 mCi of 99mTc pertechnetate. How will this affect the static brain images taken at 1 h after injection?
(a)Thyroid activity may be seen.

(b) Choroid plexus may be seen.
(c) Salivary glands may be seen.

Answer 24

(b) 99mTc pertechnetate will eventually collect in the choroid plexus. Therefore, if delayed static images are planned, oral potassium perchlorate should be given, or another radiopharmaceutical should be used.

Question 25

Radionuclide angiography is most commonly used to:
(a)Locate neoplasms

(b) Investigate brain perfusion
(c) Evaluate cerebrovascular reserve
(d) Confirm brain death

Answer 25

(d) Radionuclide angiography is commonly used to confirm brain death and may be performed using 99mTc pertechnetate, 99mTc DTPA, 99mTc GH, or the lipophilic radiopharmaceuticals 99mTc HMPAO or 99mTc ECD. The other indications listed can be better evaluated with SPECT brain perfusion studies.

Question 26

In which area is the radiopharmaceutical not visible in a normal cisternogram?
(a)Basal cisterns

(b) Cerebral convexities
(c) Lateral ventricles
(d) Sylvian fissure

Answer 26

(c) Activity in the Sylvian fissure and the basel cisterns is usually seen on early images (2-4 h) and cerebral convexities later (by 24 h). Visualization of the lateral ventricles is usually considered abnormal and may indicate hydrocephalus.

Question 27

What is the usual dose for a radionuclide cisternogram in adults?
(a)5 mCi of 111In DTPA

(b) 100 uCi of 111In DTPA
(c) 500 uCi of 111In DTPA
(d) 2.5 mCi of 111In DTPA

Answer 27

(c) Most labs use 0.5-1.0 mCi of 111In DTPA.

Question 28

What is the purpose of pledget placement in a suspected CSF leak?
(a)To make the patient more comfortable during subarachnoid puncture

(b) To alter the biodistribution of the radiotracer
(c) To test them for contamination suggesting the presence of leaking CSF in the nose or ears
(d) To avoid contamination of the scintillation detection system

Answer 28

(c) Pledgets are placed prior to radiopharmaceutical administration and are removed 4-24 h later and counted in a well counter. Blood serum is also sampled concurrently, and pledget serum count ratios are calculated; ratios greater than 1.3-1.5 are generally considered abnormal. This information is evaluated together with images of the leak site.

Question 29

Why is 111In DTPA preferred over 99mTc DTPA for cisternography in adults?
(a)Because it has lower-energy photons

(b) Because it has two photopeaks
(c) Because it has a longer half-life allowing delayed imaging
(d) Because it has a superior biodistribution

Answer 29

(c) 99mTc DTPA is not useful for evaluating CSF dynamics in adults because of its shorter half-life. Children have faster flow, so 99mTc DTPA can be used in pediatric examinations.

Question 30

Considerations for successful SPECT imaging of the brain include:
(a)Minimizing sensory stimulation during injection

(b) Minimizing patient to detector distance
(c) Immobilizing the patient
(d) All of the above
(e) (b) and (c) only

Answer 30

(d) Minimizing patient to detector distance and immobilizing the patient are important considerations for all imaging examinations in nuclear medicine. Various stimuli can affect cerebral blood flow. The Society of Nuclear Medicine Procedure Guidelines recommend preparing the patient in a quiet room with low light, obtaining venous access 10 min before injection, instructing the patient not to read of talk during the preparation period, and not interacting with the patient before, during, and immediately following injection to avoid increased uptake in relevant areas of the cortex.

Question 31

To prepare a patient for DaTscan study, which of the following is correct?
(a)NPO overnight or at least 4 h.

(b) No coffee or tea at least 12 h prior to the study.
(c) Thyroid blockage by SSKI prior to the study is required.
(d) Void before imaging.

Answer 31

(c)Thyroid blockage by SSKI or Lugol’s solution should be done prior the study. No NPO or coffee/tea abstinence is required. Voiding does not help as the imaging is limited to the head.

Question 32

For DaTscan study, which of the following is correct?
(a)DaTscan detects beta-amyloid deposition.

(b) DaTscan detects brain infarction.
(c) DaTscan detects brain presynaptic dopamine transporter.
(d) DaTscan detects brain neurofibrillary tangles.
(e) DaTscan detects brain Lewy bodies.

Answer 32

(c) DaTscan has high binding affinity for presynaptic dopamine transporter, which is decreased in patients with Parkinsonian syndromes.

Question 33

To perform a DaTscan study, which of the following is correct?
(a)Imaging can be obtained 3-6 h after tracer injection.

(b) Dedicated head holder should be used.
(c) The camera should be very close to the head.
(d) (a-c)

Answer 33

(d) It is important to keep the head in proper position and close to the camera.

Question 34

For Amyvid PET study, which of the following is correct?
(a)NPO for 4 h before the study is needed.

(b) Blood sugar <200 mg/dl.
(c) Arms should be above shoulders during imaging.
(d) Imaging can be started as soon as 30 min after tracer injection.
(e) None of the above.

Answer 34

(d) There is no need for NPO and no limit for blood sugar for Amyvid PET study, and arms should be down for head imaging.

Question 35

For Amyvid PET study, which of the following is correct:
(a)Amyvid detects brain ischemia.

(b) Amyvid detects brain atrophy.
(c) Amyvid detects brain beta-amyloid deposition.
(d) Amyvid detects brain neurofibrillary tangles.
(e) Amyvid detects brain Lewy bodies.

Answer 35

(c) Amyloid PET detects brain beta-amyloid deposition, a hallmark of Alzheimer’s disease.

Question 36

To prepare a patient for FDG-PET of the brain, which of the following is correct?
(a)NPO at least 4 h.

(b) No coffee or tea at least 12 h prior to the study.
(c) Blood sugar should be <200 mg/dl.
(d) Imaging can be started as soon as 30 min after tracer injection.
(e) All of the above.

Answer 36

(e) Coffee or tea may stimulate the brain activity. Brain FDG-PET imaging can be obtained as soon as 30 min after tracer injection.

Question 37

Amyloid PET imaging is most helpful in patients with which of the following conditions:
(a)Suspected Parkinson’s disease but without definite diagnosis

(b) Suspected Alzheimer’s disease but without definite diagnosis
(c) Clinically diagnosed Parkinson’s disease, to confirm with imaging findings
(d) Clinically diagnosed Alzheimer’s disease, to confirm with imaging findings

Answer 37

(b) Amyloid PET imaging is most helpful in patients with clinically suspected Alzheimer’s disease, but not needed in patients with clinically diagnosed Alzheimer’s disease.

Question 38

As of 2016, radiotracers that have been approved by FDA for imaging AB plaques include all of the following except:
(a)18F-florbetapir (Amyvid)

(b) 18F-flutemetamol (Vizamyl)
(c) 18F-florbetaben (NeuraCeq)
(d) 11C-Pittsburgh Compound B (PIB)

Answer 38

(d) 11C-Pittsburgh Compound B (PIB) is the initial investigational candidate for imaging Alzheimer’s disease.

Question 39

For Amyloid PET study, a patient should:
(a)Be on NPO overnight.

(b) Hold medicines on the day of imaging.
(c) Hold medicines working on the central nervous system only, on the day of imaging.
(d) Have no special preparations regarding diet and medicine.

Answer 39

(d) No special patient preparations regarding diet and medicine for amyloid PET study.

Question 40

Which of the following is not correct regarding the recommended dose and waiting period before Amyloid PET image acquisition?
(a)18F-florbetapir, dose of 370 MBq (10 mCi), waiting period of 45 min.

(b) 18F-flutemetamol, dose of 185 MBq (5 mCi), waiting period of 90 min.
(c) 18F-florbetapir, dose of 370 MBq (10 mCi), waiting period of 120 min.
(d) 18F-florbetaben, dose of 300 MBq (8 mCi), waiting period of 120 min.

Answer 40

(c) 18F-florbetapir, dose of 370 MBq (10 mCi), waiting period of 120 min.

Question 41

Amyloid PET is indicated in patients with the following conditions EXCEPT:
(a)Persistent or progressive MCI with uncertain clinical diagnosis

(b) Diagnosed Alzheimer’s disease, to determine the severity of dementia
(c) Clinically suspected possible Alzheimer’s disease but with atypical clinical course
(d) Clinically progressive dementia with an early onset (65 years of less in age)

Answer 41

(b) Amyloid PET imaging is most helpful in patients with clinically suspected Alzheimer’s disease. However, positive findings on amyloid PET cannot be used to confirm the diagnosis or to determine the severity of Alzheimer’s disease.