0:01

So we have previously seen a case

0:03

of a normal distribution.

0:05

Now let's see how an abnormal distribution

0:08

of FDG looks like.

0:11

This patient underwent a FDG injection

0:15

and, uh, scanning.

0:16

And afterwards, uh, we saw this

0:19

and the difference with the other case is that the majority

0:22

of your tracer is in the skeletal muscle

0:25

and myocardium as opposed to the other case

0:29

where there was uptake in the organs and minimal

0:34

or very low uptake in the musculature.

0:37

This is the classic distribution of, uh, case

0:42

of hyperinsulinemia.

0:45

Now remember, we check the glucose levels before the study

0:50

and it might be that the blood glucose is normal when we are

0:53

going to inject because we do not detect

0:57

and we don't quantify the level of insulin that is in blood.

1:01

This patient had not understood well the instructions

1:04

and had eaten within the last four hours prior to the study.

1:07

And even though the blood glucose was normal,

1:10

clearly there was insulin acting in the body

1:14

and that insulin made the glucose go to those

1:19

organs that are insulin dependent.

1:22

As we mentioned in the basic concepts,

1:25

which is your myocardium

1:27

and your skeletal muscle, it's important to realize

1:31

and identify when, uh, the distribution is abnormal

1:35

because these might lead to non-diagnostic study

1:40

in areas where there is abnormal uptake.

1:44

For instance, in this lesion in the left breast

1:48

where there is a primary, it may actually

1:53

decrease the intensity of tracer, mainly

1:56

because the tracer is being diverted to other organs instead

2:00

of primarily to the malignancy.

2:04

But it also can happen that you actually miss

2:08

or you cannot identify areas of

2:11

otherwise abnormal uptake.

2:15

So in this case, uh, patient had a repeat pet,

2:20

and so we are gonna be able to compare the

2:24

poor preparation with the appropriate preparation.

2:28

So on the bottom we have the pet CT that was initially done

2:33

with the poor preparation.

2:37

On the top we have the repeated pity,

2:39

and even though we have a lot going on on this patient,

2:42

we're gonna focus on the primary lesion,

2:45

which was the left breast nodule.

2:49

So first, let's put both pets at the same scale

2:53

and compare the intensity.

2:54

Visually you can see a difference, but also when we apply

2:59

The ROI to calculate the activity,

3:02

we can also see the difference in degree of uptake.

3:06

On the bottom, the SUV max is 4.9,

3:10

and on the repeat study is 8.3.

3:14

This, uh, shows you the importance of good preparation.

3:19

On the initial study, there was an area

3:21

that had a faint focal haptic that was raised

3:24

as a possible secondary lesion.

3:26

And look how obvious it becomes on the repeat study.

3:32

Same goes with the nodal involvement in the left axi,

3:36

where the degree of uptake, it's lower on the

3:40

initial pit compared to the repeated pit on top with

3:46

they're a little bit mis registered,

3:47

but on the initial, the SUV max is 3.7,

3:51

and on the repeat one is 6.4.

3:54

So how to approach these cases?

3:56

Well, number one would be to

3:59

first identify when the distribution is abnormal.

4:03

And second, I would encourage to try to, uh,

4:07

investigate why the distribution was abnormal,

4:10

was a problem in the instruction.

4:12

Uh, how the instructions were given was, uh, that, uh,

4:16

a language barrier patient, uh, didn't understand

4:20

that certain drinks, for instance, is very common.

4:23

That patient drink during the, the four to six hours prior

4:28

to the scan, they are allowed to drink water,

4:30

but they might not know

4:31

that the drink they are consuming have actually glucose.

4:35

So that is important because if you're gonna repeat the

4:37

study, you want it to be the agnostic.

4:40

Second of all, it's always important to recognize

4:43

that even though your glucose levels might be normal, the

4:47

insulin is something that is, uh, obscured to us.

4:51

We, we don't see really what's going on until

4:54

the patient gets scanned.

4:56

Third, I would contact the clinician to make them aware

5:00

of the situation

5:02

and tell them that, to tell them that it's non-diagnostic

5:05

so they can help

5:07

and they can, you know, encourage the patient to come back

5:11

to repeat the study.