0:01

In this video we're gonna talk about

0:03

the most commonly used tracer called fluoro,

0:06

the oxy glucose, or most commonly known as FDG.

0:10

So let's talk about some basic concepts.

0:14

FDG is a glucose molecule analog, which means

0:18

that it's very similar to glucose.

0:22

And the only difference is

0:24

that we substitute an the F 18

0:27

where there is a hydroxy group.

0:31

But the behavior of both is gonna be very similar.

0:35

Both glucose and FDG will be trapped in the cell via

0:40

glute, which are glucose transporters.

0:43

Then they will go phosphorylation by exo kinase.

0:49

And the difference will be that

0:51

a normal glucose molecule will go through glycolysis,

0:55

whereas FDG will not be able to go through lysis

1:00

and will remain trapped.

1:03

The rate in which FDG accumulates is directly proportional

1:08

to the, to the level of glucose transporters,

1:12

but also will depend on the amount of

1:17

hexokinase within the cells.

1:20

So this is a common mechanism that exists in both

1:24

normal cells and malignant cells.

1:27

As you can already predict, there will be some times

1:31

where it will be hard to detect disease,

1:35

so it will go through all that.

1:37

Uh, later in the course, every organ in the body will

1:42

express glucose transporters.

1:44

There are five of them

1:46

and um, some of them are insulin independent

1:50

and a few are insulin independent.

1:52

And this will be important when we discuss the

1:56

patient preparation.

1:57

Blood glucose, exogenous glucose, endogenous glucose,

2:02

and FDG will all compete for those glucose transporters.

2:07

So preparation for FDG is key.

2:10

And just to touch a little bit on the red regulation of

2:13

blood glucose to refresh, uh, from medical school

2:19

when, uh, there is high glucose level in blood,

2:23

the pancreas will release insulin to trap

2:28

glucose into the, the cells that need glucose.

2:32

And uh, also, uh, we'll convert it into glycogen

2:37

for storage, and that way insulin will be able

2:40

to lower the glucose levels.

2:43

FDG is our mostly used tracer.

2:46

The importance of this tracer is that it allows us

2:49

to identify areas of malignancy.

2:53

It allows us to help stage the patients

2:57

and also assess

2:58

For treatment response.

3:01

It's safe to say that higher grade malignancy

3:04

or less differentiated tumors are associated

3:07

with higher levels of FDG accumulation

3:10

because they increase the expression of glu transporters to

3:15

trap more glucose for growth.

3:19

And therefore we take advantage of this.

3:21

It is also in general good to say that, um,

3:25

the higher degree of FDG accumulation is associated with,

3:29

uh, poor prognosis.

3:31

It is important to realize that not all the tumors

3:34

are well seen with FDG,

3:36

and then this will be covered in other areas of the course,

3:40

but it is commonly used in the practice

3:44

for a wide variety of malignancies.

3:48

And so I hope that through this course you get familiar

3:51

with this tracer, it's distribution

3:54

and how much you can provide

3:56

to the clinician from this scan.