Other random questions

Question 1

What is involved in a PET scan?

Answer 1

Injection of a glucose analogue (18F-FDG) which is taken up by cells with glucose transporter proteins.
Glucose is then phosphorylated by hexokinase to FDG-6 phosphate and FDG-phosphate is trapped in the cells.
Malignant cells have a high metabolic rate and high level of uptake of glucose

Question 2

What can give a false negative on a PET scan?

Answer 2

Raised serum glucose as less FDG will be taken up by tumour cells as normal glucose is competing for receptors - patients are usually fasted before a scan to prevent this

Question 3

What are sites on a PET that physiologically take up FDG?

Answer 3

Brain
Urinary system
Liver and spleen

Question 4

What can give a false positive on a PET?

Answer 4

Brown fat
Infections (Tb)
Sarcoidosis
Recent surgery

Question 5

What are some FDG-PET negative tumours?

Answer 5

Bronchoalveolar carcinoma
Carcinoid tumours of lung
Renal cell carcinomas
Hepatomas
Low grade lymphomas
Mucinous tumours of GI tract
Low sensitivity at detecting osteoblastic (sclerotic mets)