Chapter 17: Positron Emission Tomography

Which of the following radionuclides is not a positron emitter?

C-14

When a neutron-deficient nucleus emits a positron:

The atomic mass number is unchanged

Which of the following has the shortest half-life?

Rb-82 has a half-life of 1.3 min.

Which of the following will not affect the distribution of F-18 FDG on a PET image?

All of the above affect distribution

Normal F-18 FDG distribution would show the least activity in the

Bladder

Al positron-emitting isotopes are produced in a cyclotron

False

F-18 FDG PET is not an important tool for:

Detecting Helicobacter pylori

Which of the following is a true characterization of FDG?

It is taken up by disease-free myocardium

F-18 FDG PET images show a map of the distribution in the body

Glucose

What length of time should a lactating female who undergoes F-18 FDG PET scanning wait before resuming breast-feeding?

24 h

Because of the relatively high energy of the photons detected in PET imaging, attenuation correction does not need to be performed.

False

What part of a PET scanner quality control regimen is necessary for the computation of attenuation factors?

Blank scan

Which of the following describes a random coincidence?

The simultaneous detection of photons originating from different positrons

Which of the following is not a scintillation crystal found in PET cameras:

Lead sulfate (PbSO4)

PET images may be reconstructed using:

Filtered a backprojection

Following a positron annihilation, two 511 keV photons are emitted in opposite directions. If one of the photons is deflected in the body:

The deflected photon may be detected outside the correct LOR

A patient has undergone myocardial PET scans using I3N ammonia and F-18 FDG. There is little inferoapical activity on the ammonia scan, but there is homogeneous uptake in the same area on the FDG images. This suggests that:

The inferoapical area may revascularize

Patient A and Patient B are injected with the same dose of N-13 ammonia for a myocardial PET scan. The patients are the same height, but Patient A weighs 120 lbs while Patient B weighs 180 Ibs. From which patient would more true coincidences be detected?

True

Chewing gum between injection of F-18 FDG and PET scanning will have no effect on the resulting images.

False

Why is it important to know if a patient has an inflammatory condition before performing an F-18 FDG PET scan?

Some inflammatory conditions cause areas of increased uptake of F-18 FDG

Patient preparation for an I&FDG-PET scan of the whole body includes:

Fasting state of at least 4-6 h prior to injection

F-18 FDG is useful for imaging tumors because:

All of the above

Which dose and route of administration are the best choices when performing a whole body PET scan with F-18 FDG and a dedicated PET scanner?

10-20 mCi IV

Fill in the blank. High blood glucose levels may_____ F-18 FDG uptake in tumors.

Decrease

Relative to one another, Rb-82 and Sr-82 are:

Isobars

What determines the lower limit of spatial resolution in PET scanners?

Positron range

Parenteral nutrition should be discontinued for several hours prior to F-18 FDG imaging.

True

Two unrelated annihilation photons are detected within the timing window and judged to be in coincidence. This is called a:

Random coincidence

Noncolinearity refers to:

Annihilation photons that are not emitted at exactly 180° to one another due to particle momentum

On an F-18 FDG-PET scan of the whole body, muscle uptake can be decreased by:

All of the above

Dedicated PET scanners use:

Electronic collimation

Standardized uptake values are useful for:

Assessing response to treatment

A patient presents for PET scanning with F-18 FDG for suspected tumor of the left axilla. Which injection site should be avoided?

Left antecubital vein