PET in prostate cancer

Question 1

What is the role of imaging in prostate cancer?

Answer 1

Primary tumor:
- diagnosis
- localization
- characterization
- determination extracapsular spread
- guidance + evaluation local therapy

Lymph nodes:
- staging locoregional lymph nodes

Furthermore:
- detection of locally recurrent and metastasizing disease
- planning radiation treatment
- prediction tumor response to therapy
- monitoring active surveillance
- prognostication castration refractoriness

Question 2

What are things to take into consideration when developing imaging modalities for prostate cancer?

Answer 2

• Anatomy and function → combined/hybride techniques
• Enough signal → suitable tracers for prostate cancer
• Imaging all metstases → whole body scan

Question 3

What is hybrid imaging?

Answer 3

Hybrid imaging refers to the fusion of two (or more) imaging modalities to form a new technique. By combining the innate advantages of the fused imaging technologies synergistically, usually a new and more powerful modality comes into being. Examples are: PET-CT, PET-MRI, etc.

Question 4

What can be monitored with PET imaging?

Answer 4

• In vivo functional imaging
• Quantification of perfusion, metabolism, enzyme activity, receptor density
• Drug tumor targeting and response therapy

Question 5

Structural imaging can be done by…

Answer 5

• CT
• MRI

Question 6

PET/MRI is an important technique in clinical practice. There are two types of PET-MRI systems, what are these?

Answer 6

• sequential acquisition mode
• simultaneous acquisition mode

Question 7

PET data analysis can be divided in 3 major groups. Name these.

Answer 7

1. Qualitative analysis or visual assessment
2. Semi-quantitative analysis
3. Absolute quantitative analysis

Question 8

What is meant with the qualitative analysis or visual assessment of PET data?

Answer 8

It is the basis of any PET study, it is the determination of non-numerical information about e.g. possible cancer development by looking at the PET images.

Question 9

What is meant with the semi-quantitative analysis of PET data? Explain what standardized uptake value (SUV) and lesion-to-background ratio is.

Answer 9

• The standardized uptake value (SUV) is a semiquantitative measure of the tracer uptake in a region of interest that normalizes the lesion activity to the injected activity and a measure of the volume of distribution (usually total body weight or lean body mass).
• Lesion-to-background ratio is a measure of the specificity of radiopharmaceutical uptake within the target organ in a nuclear medicine study.

Question 9

Prostate-specific membrane antigen (PSMA) is a type-2 transmembrane protein. How does this protein relate to prostate cancer?

Answer 9

The level of expression of PSMA correlates with the prognostic outcome. A high level of PSMA expression correlates with a poor prognostic outcome.