0:01

In this section we're gonna go over how to display

0:04

and read a pet study.

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In this section we'll discuss some points

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that have been also covered in other sections,

0:11

but this section is meant

0:12

to be more practical, less theoretical.

0:15

So let's dive in. This is going to be the content.

0:19

We are going to discuss basic information from

0:22

the PET CT study.

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Uh, we're gonna see a report example, this is the one I use.

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We're gonna discuss basic components of the PET CT

0:32

and specifically discuss the non attenuation corrected

0:35

images and attenuation corrected images.

0:39

We are going to go over a study together

0:43

and I'm gonna, uh, show you my systematic approach

0:47

and then we'll briefly mention the most common protocols.

0:51

So where to start. This listed information

0:56

is the most basic

0:58

and should be available to you in different ways.

1:03

Uh, each uh, institution works a little bit different,

1:06

but you should be given indication

1:10

what the tracer is that you've administered in case

1:16

of an FDG pet.

1:18

You also want to know the blood glucose level.

1:21

If the patient is diabetic,

1:24

was the patient on any medication such

1:27

as insulin or metformin?

1:30

Did the patient follow the instructions of fasting?

1:35

Other things that are important to know are the site

1:38

of injection because sometimes when there's a little bit of

1:42

extravasation and infiltration of the tracer, this may lead

1:46

to uptake in axillary lymph nodes

1:50

as we commonly inject in the anti cubital fossa.

1:53

And that would help you troubleshoot the interpretation

1:57

of these lymph nodes.

1:59

Also very important is the uptake phase can also be called

2:02

delta phase uptake phase or delta time.

2:06

And this is the time between the injection

2:10

of the tracer and the imaging.

2:12

Each tracer will require a different range of time,

2:17

and it is important to mention that in your report

2:22

and, uh, notice if this is,

2:24

if the time is longer than expected.

2:27

For each tracer in the section of imaging acquisition

2:31

and quantification of activity, we mentioned

2:34

that there are certain factors

2:36

that may affect the SUV calculation

2:40

and that's why this item is important

2:43

as this is one of them.

2:45

It would also good to have access

2:48

to relevant clinical information such as prior history of

2:52

surgeries or, uh, recent vaccination.

2:55

I noticed this particular item in

2:58

Orange because particularly

3:01

after COVID-19 pandemic

3:05

and the vaccination

3:07

and booster, we saw an increase in number of cases

3:11

that had, we saw reactive lymph nodes that made

3:16

sometimes cases more challenging to interpret

3:21

as differentiating malignancy from reactive lymph

3:26

nodes was difficult.

3:28

Other things that, uh, would be important to have is access

3:31

to recent or remote imaging,

3:33

particularly if those studies are from outside

3:38

specific medications.

3:40

Some physicians add the last menstrual cycle date

3:45

because, um, this may

3:48

help you interpret the variable activity in the endometrium

3:52

and ovaries in female patients as well as, uh,

3:55

other prior treatments.

3:58

So here I'm showing you what we have, uh,

4:03

at my institution, this Willy Fair,

4:05

you know, center to center.

4:07

But I'm showing you the example of

4:09

how all these information is available to us.

4:13

On top we have the patient date and date of birth

4:18

and we have the indication,

4:23

we have the code for the study

4:26

and important information also

4:27

for the study is the height and weight.

4:30

Then we have, uh, category of data that is related

4:35

to the injection, what the tracer was, the site

4:38

of the injection, and the time as well as the dose

4:42

in the prescreening data.

4:44

We ask if the patient has been fasting, the glucose level,

4:49

and uh, other relevant information specific to the patient.

4:54

We have under the medical history.

4:58

We have added, for instance, surgical history

5:01

and patient can list their surgeries.

5:03

Sometimes you will find that these are relevant,

5:05

some are not, but it's always good to have that available

5:09

if there's recent imaging.

5:11

And, uh, we started adding in additional notes the

5:15

history of vaccination.

5:17

As I mentioned earlier, for a specific brain studies,

5:22

we have additional questions for other type of studies

5:26

that are non oncologic like cardiac pits.

5:29

We also have more questions as well in orange and marking.

5:34

The one that is more relevant for FDG,

5:37

probably FDG is the one

5:39

that you're gonna be reading the most.

5:41

So always remember to make sure that the preparation

5:46

of the patient is appropriate

5:48

and that you have glucose levels that are within the range,

5:53

uh, where you can inject the tracer. So before

5:56

I read a pity, I try to find out the following questions.

6:01

Number one is, what is the indication

6:05

or what is the specific question to answer

6:08

because I want to address this in my report,

6:11

but particularly in my impression.

6:14

Number two, is there a diagnosis already?

6:17

And then this would be for staging

6:19

or do we need to guide

6:24

the clinician for tissue sampling?

6:28

Number three is, do we know where the primary lesion was

6:32

or the extent of disease on priors?

6:35

And in this case, I actually more often than not go back

6:39

to even the baseline PET

6:41

or baseline imaging to understand where was the disease

6:46

and how extensive and how it has changed over time.

6:49

It becomes very relevant to understand the treatment

6:52

timeline, particularly when certain therapies were started

6:58

and if there has been an interval change.

7:02

Also, it's important to know if this is a baseline

7:05

or is this a new baseline after, uh, treatment.

7:09

And also as a fourth uh, question,

7:13

have there been any changes in other imaging or new symptoms

7:17

or something that has triggered

7:20

the acquisition of this PET ct?

7:23

So for every PET C, you will

7:26

commonly find three type of series.

7:30

The first one will be the city,

7:32

the second one will be the non attenuation corrected

7:35

PET series.

7:37

And then the third one will be the attenuation

7:39

corrected PET series.

7:42

Names may differ depending on vendors,

7:44

but you should always be

7:47

provided with these three series

7:50

have listed the three most common protocols.

7:53

And I add this in the technique section of the reports,

7:58

obviously for billing purposes,

8:00

but most importantly to make the clinician

8:05

that is reading the report aware of what areas were included

8:09

and what areas were not.

8:11

So the most commonly used protocol is gonna be from the

8:14

skull base to mid thigh.

8:17

Then we can include the, from the vertex of the skull

8:20

to mid thigh in cases of head and neck cancer.

8:24

Or in cases

8:25

where we know there's an abnormality somewhere in the skull,

8:30

we want to make sure it's included.

8:32

And the third one would be a whole body which extends

8:36

from the vertex of the skull to the toes.