SPECT

Question 1

What does SPECT stand for?

Answer 1

Single Photon Emission Computed Tomography

Question 2

What kind of camera is used in SPECT?

Answer 2

a dual headed gamma camera

Question 3

How much rotation is used for general SPECT scans?

Answer 3

360 degrees

Question 4

How much rotation is sued for cardiac SPECT scans?

Answer 4

180 degrees

Question 5

What is the difference between SPECT and PET?

Answer 5

The main difference between SPECT and PET scans is the type of radiotracers used. While SPECT scans measure gamma rays, the decay of the radiotracers used with PET scans produce positrons.

Question 6

What factors can corrupt image quality in SPECT?

Answer 6

photon attenuation
scatter
depth-dependent collimator (spatial resolution) response

Question 7

What is used to compensate for bad image quality in SPECT?

Answer 7

Software corrections

Question 8

What is important before starting the scan?

Answer 8

To identify and correct the alignment, an experimental center of rotation procedure is performed.

Question 9

What processes are used for image reconstruction in SPECT?

Answer 9

Filtered back projection
Iterative reconstruction

(same as CT)

Question 10

Why might iterative reconstruction be preferred to FBP?

Answer 10

Quantitatively more accurate as it can model various corrections including the collimator, scatter,
system geometry & detector resolution

Question 11

A disadvantage of iterative recosntruction

Answer 11

Slow and requires a large computing power

Question 12

What results in attenuation in SPECT images/

Answer 12

the interaction of photons via photoelectric absorption and Compton scatter within the patient results in attenuated projections

Question 13

How to correct for attenuation of emitted photons?

Answer 13

Using a hybrid SPECT-CT system

Question 14

Scatter results in…

Answer 14

loss of contrast and loss of quantitative accuracy

Question 15

How is the scatter component estimated?

Answer 15

Using data acquired in auxiliary energy windows, and the Triple energy window (TEW) method

Question 16

What does scatter correction require?

Answer 16

Scatter correction requires both estimating the scatter component of the projection data combined with a compensation method.

Question 17

How long does each projection take with the gamma camera?

Answer 17

20 seconds

Question 18

What is the full scan time?

Answer 18

20 minutes

Question 19

What is a major factor in SPECT?

Answer 19

Quantum mottle

due to the low number of photons used to reconstruct each voxel

Question 20

What is the major benefit of SPECT?

Answer 20

better contrast due to the elimination of overlapping structures. This leads to better lesion conspicuity

Question 21

What is the most common use of SPECT CT

Answer 21

Myocardial perfusion imaging

Question 22

What else can result in artefacts?

Answer 22

The SPECT scan and the CT scan do not occur at once. This can result in misregistration artifacts if any organ moves between scans