Oncology Procedures Board Practice Questions

A tumor tracer that lights up any tissue with high glucose use, including infection, is best described as what kind of agent?

Nonspecific metabolic agent (FDG)

Which tracer-target pairing is correct?

PSMA ligand - prostate cancer

What does Ga-67 citrate bind to in order to reach tumor cells?

Transferrin, via the CD71 receptor

For antibody-based imaging agents, what mainly determines how long you wait before imaging?

Molecule size

Which order correctly ranks blood clearance from slowest to fastest?

Whole antibody, then fragment, then peptide/amino acid

A patient is scheduled for capromab pendetide (ProstaScint), arcitumomab (CEA-Scan), and fluciclovine (Axumin) studies. Which needs the LONGEST wait before delayed imaging?

ProstaScint (whole antibody, days)

What is HAMA?

Human anti-mouse antibody response to a murine antibody

A patient who received a murine antibody scan 1 year ago is scheduled for a repeat dose. What should be checked first?

HAMA titer

Which type of imaging agent does NOT trigger a HAMA response?

Small peptides and amino-acid analogs

Why does a SPECT acquisition need more counts than a single planar view?

The counts are spread over many projection angles

CALC: The planar In-111 pentetreotide dose is 3 mCi. If SPECT is planned, the guide doubles it. What is the SPECT dose in MBq?

222 MBq (6 mCi)

What does adding CT to a SPECT tumor study provide?

Better detection and localization

Which is a study contraindication for SPECT/CT tumor imaging?

A patient who can't lie still

Before pelvic SPECT, what prep is common?

Void and remove metal

In the guide, 'total/whole-body' tumor imaging most often refers to which study concept?

I-131 whole-body survey

Which parameters fit the diagnostic I-131 whole-body survey concept?

1-4 mCi, image 24-72 h, high-energy collimator

A planar tumor study shows a pelvic focus that could be bladder, bowel, or a node. What best resolves it?

SPECT/CT to localize it anatomically

Why do most cancer cells accumulate FDG?

High glycolysis (more GLUT, hexokinase)

Through which transporters does FDG enter cells?

GLUT transporters

Which enzyme phosphorylates FDG inside the cell?

Hexokinase

Why does FDG-6-phosphate stay trapped in tumor cells?

Tumors have little glucose-6-phosphatase to reverse it

What is FDG's localization mechanism called?

Metabolic trapping

How is F-18 for FDG produced?

Cyclotron, by proton bombardment of O-18 enriched water

What is the physical half-life of F-18?

About 110 min

What photon energy does a PET scanner detect?

Two 511 keV photons, about 180 degrees apart

How is FDG excreted?

Urine (not reabsorbed by the tubules)

What is the critical organ for FDG?

Urinary bladder wall

Which normal organ has the highest baseline FDG uptake?

Brain

A patient's FDG scan shows intense heart uptake, and his prior scan showed almost none. What explains this?

Normal variable myocardial uptake

Which tumor type is commonly FALSE NEGATIVE on FDG?

Well-differentiated neuroendocrine tumor

Which group lists common FDG false positives?

Infection, inflammation, brown fat, muscle

Why can FDG and Ga-67 both light up infection as well as tumor?

Inflammatory cells are active too

Which payer limits FDG reimbursement to specific cancer indications, per Bolus?

CMS (Medicare)

Which four factors is FDG patient prep mainly trying to control?

Glucose, insulin, exercise, and cold

What is the minimum fast before body FDG PET?

4-6 hours, water only

A patient on an FDG fast asks what he can drink. What is correct?

Plain water only

Per Bolus, fasting before FDG mainly reduces uptake in which organ?

The heart

What is the general blood glucose limit for body FDG PET?

200 mg/dL or less

A non-diabetic patient's pre-FDG glucose is 235 mg/dL. What is the best action?

Reschedule or correct glucose; don't inject

How does high blood glucose affect FDG tumor uptake?

Lowers it; glucose competes with FDG

What happens to FDG distribution if insulin is given shortly before injection?

FDG is driven into skeletal muscle and fat

A patient's FDG scan shows intense diffuse muscle uptake and poor tumor contrast. He received insulin 20 minutes before injection. What went wrong?

Insulin given too close to FDG drove it into muscle

Per the guide, how long after IV insulin should FDG be injected?

At least 60 minutes (ideally about 90)

CALC: IV insulin is given at 09:00 to correct glucose. Per the guide, what is the earliest FDG injection time?

10:00

Per EANM, how long after a rapid-acting SUBCUTANEOUS insulin dose should FDG be given?

At least 4 hours

How long should strenuous exercise be avoided before FDG PET?

24-48 hours

A patient ran a marathon yesterday and has an FDG PET today. Which artifact is most likely?

Intense symmetric skeletal muscle uptake

Why must an FDG patient be kept warm before and during uptake?

Cold activates brown fat, which avidly takes up FDG

What uptake room temperature is recommended for FDG patients?

At least 75 degrees F (about 24 C)

An FDG scan in January shows symmetric uptake in the neck, supraclavicular, and paravertebral fat. What is it?

Brown adipose tissue activation

What is the FDG prep 'paired trap' the boards like to test?

Rest, but stay warm

How much oral water is suggested before FDG?

1-2 L

A hospitalized patient is on a dextrose IV drip and tube feeds. Can the FDG fast proceed as usual?

No; stop dextrose and tube feeds

Per Bolus, why might a mild sedative be given during FDG uptake?

Keeps tense muscle from mimicking disease

Which sedatives may be used during FDG uptake?

Diazepam (Valium) or lorazepam (Ativan)

Why might a diuretic or bladder catheter be used with FDG?

To clear urinary activity that hides pelvic lesions

What is a common furosemide dose to flush urinary FDG activity?

20-40 mg IV

What should the patient do during the FDG uptake period?

Rest quietly without talking

A patient talked on the phone throughout the FDG uptake period. Which artifact may result?

Increased laryngeal (vocal cord) uptake

What does Bolus say may be given the night before FDG?

A laxative

CALC: A pre-FDG glucose reads 200 mg/dL. What is that in mmol/L (divide by 18)?

About 11.1 mmol/L

CALC: A diabetic's glucose is 150 mg/dL. What is that in mmol/L?

About 8.3 mmol/L

A diabetic patient took his usual morning intermediate-acting insulin 2 hours before arriving for FDG PET. Glucose is 140 mg/dL. What is the concern?

Insulin effect may shift FDG into muscle; reschedule

A patient sat in a cold waiting room for 45 minutes in winter before FDG injection. Which prep step was missed?

Keeping the patient warm to prevent brown fat uptake

A patient chewed gum throughout the FDG uptake period. Which artifact is most likely?

Increased masseter (jaw muscle) uptake

What is the usual adult FDG dose for body oncology imaging?

10-20 mCi (370-740 MBq) IV

What is the standard FDG uptake time?

About 60 minutes

What is the standard field of view for body FDG PET/CT?

Skull base to mid-thigh

For which cancers is FDG PET extended to a true whole-body (vertex-to-toe) field?

Melanoma, myeloma, sarcoma, kids

A melanoma patient's primary lesion was on the left foot. What FDG field of view is required?

Vertex to toes

Why is FDG PET poor at finding melanoma brain metastases?

High normal brain glucose use hides small lesions

Which study is used to evaluate melanoma brain metastases?

Contrast-enhanced brain MRI (or CT)

How are the arms positioned for body FDG PET/CT?

Overhead

What two acquisitions make up an FDG PET/CT?

PET emission scan plus CT for attenuation correction

How are FDG PET images displayed for reading?

AC and non-AC in 3 planes, plus MIP

A lesion is hot on the attenuation-corrected PET but not on the non-attenuation-corrected images, right next to a metal hip. What should be suspected?

CT-based attenuation-correction artifact from metal

What does an abnormal FDG focus look like?

Focal or asymmetric uptake

Which list best matches normal FDG biodistribution?

Brain, variable heart, liver, bowel, kidneys, bladder

Where is brown adipose tissue typically found?

Neck, supraclavicular, spine fat

What is the pediatric FDG dosing principle?

Weight-based, with a minimum activity

Why does every pediatric dose have a minimum activity?

Below it, counts are too low to read

A melanoma patient has a negative FDG PET/CT. What follow-up is typical?

Clinical skin and node exams

On brain FDG PET, how does a high-grade glioma typically look?

Intensely hot

On brain FDG PET after radiation, a lesion is cold. What does this favor?

Radiation necrosis

How long after radiation therapy should you wait before brain FDG PET for suspected recurrence?

4-6 weeks

An AIDS patient has a ring-enhancing brain lesion that is HOT on FDG. What is more likely?

CNS lymphoma

An AIDS patient has a ring-enhancing brain lesion that is COLD on FDG. What is more likely?

Toxoplasmosis

Which brain lesion is typically COLD on FDG?

Low-grade tumor

What uptake environment is used for brain FDG?

Quiet, dim room, eyes open

Per the guide, what is the usual brain FDG dose for oncology?

About 10 mCi (range 10-20 mCi)

On a skull-base-to-thigh FDG PET for a thigh melanoma, the lower legs weren't imaged. What went wrong?

Melanoma needs vertex-to-toe coverage

A post-op patient's FDG scan shows linear uptake along a 3-week-old surgical incision. What is the most likely explanation?

Normal healing (false positive)

An FDG scan shows a hot spot in the antecubital fossa at the injection site and low uptake everywhere else. What should be suspected?

Dose extravasation

A body FDG PET/CT is negative in a patient with a known well-differentiated NET. What is the correct interpretation?

Reassuring, but low-FDG tumors can be missed

CALC: Using North American consensus dosing (3.7 MBq/kg, minimum 26 MBq), what FDG dose does a 20 kg child get?

74 MBq (2 mCi)

CALC: Using 3.7 MBq/kg with a 26 MBq minimum, what FDG dose does a 5 kg infant get?

26 MBq (the minimum)

Per the guide's FDG tracer table, when does brain FDG imaging typically start?

30-40 min after injection

What is the SUV formula?

Tissue activity (kBq/mL) / [injected dose (kBq) / body weight (g)]

What does an SUV of about 1 mean?

Tracer spread evenly

For SUV, 1 g of body weight is assumed to equal about what?

1 mL