Interactive Transcript
0:02
Hello and welcome to Noon Conferences hosted by MRI Online.
0:06
In response to the changes happening around the world right now and the
0:09
shutting down of in person events, we have decided to provide free Noon
0:12
Conferences for radiologists all around the world. Today we are joined for
0:16
a noon conference by Dr. Elcin Zan. She is a radiologist who specializes
0:20
in neuroradiology and nuclear medicine with a focus on theranostics, combining
0:25
imaging and therapy. A reminder that there will be a Q&A session at
0:29
the end of the lecture, so please use the Q&A feature to ask
0:32
your questions and we will get to as many as we can before
0:34
our time is up. That being said, thank you all for joining us
0:38
today. Dr. Zan, I'll let you take it from here. Well, good afternoon, good
0:43
morning or good evening, wherever you are. Thank you very much for joining
0:46
us. I will be talking about molecular PET in head and neck oncology. Those
0:51
are my disclosures but nothing relevant to the topic we will discuss here.
0:55
We will talk about the major differences between molecular PET and radiology,
0:59
and we will see the proven value of FDG PET in head and neck oncology and
1:05
the pending value of DOTA TATE PET in head and neck oncology. Instead
1:09
of providing you the sensitivity and specificity analyses from the literatures,
1:14
I will be very practical and I will share you cases.
1:18
All of them are my own cases from NYU,
1:22
the institution that I work right now, because I want to show the
1:25
real value of how practical the molecular PET could be in the real
1:29
world, except the last case and we will see. So I'm going to
1:33
stop my video so that we can all focus on the images. Let's
1:41
start with the differences. What's the biggest difference between anatomic
1:45
versus PET imaging? That's the basic question between radiology and molecular
1:50
nuclear medicine practices. In radiology, as we can see here, we have an
1:54
external source, whether it's a CT or MRI, and it is an organ based
2:00
imaging, whether you scan the brain, head, or neck, or part of the
2:03
body, it's organ based. So the biggest amount of data that you can
2:08
collect is going to give you the information about the local,
2:12
T, and nodal, and staging. As opposed to PET, it's an emission scan. We
2:18
inject a small amount of, a minor amount of radiopharmaceutical, and then
2:23
the body becomes the source of our signal, the body becomes the
2:31
signal emitter, and the PET scanner collects the signal from the patient's
2:35
body. That is a product of the inherent physiologic or pathologic states.
2:43
So the difference is, again, anatomic, organ based,
2:48
and it's a transmission scan, because we are an external source, as opposed
2:53
to PET's molecular, it's a functional imaging, because we inject the patient,
2:59
and then after a while, we image the patient as a whole,
3:03
the entire body, to see the physiologic as well as the pathologic processes.
3:08
And one of the fundamental differences aside from the techniques or technical
3:14
equipment that we use is the PET tracers versus the gadolinium, because
3:19
in CT or MRI, we use contrast, and mostly in... The example shown
3:25
here is a blood vessel that shows how the contrast
3:30
enhancement happens, as opposed to the PET, molecular PET, radiopharmaceuticals
3:36
and the molecules at the top. So let's focus on
3:41
the gadolinium first on MRs, which the same applies to the iodine. You
3:45
do have either increased number of vessels within the
3:50
mass or wherever the disease is, and this increased number of vessels are
3:55
not healthy vessels. They are leaky, as you can see here,
3:58
and they let either the iodine or the gadolinium to leak through the
4:02
vessels, and that creates your enhancement and the recognition of the mass
4:06
or lesions. And this is a very passive process. There is nothing specific
4:12
to the type of the disease. Everything can enhance right. As opposed to
4:16
the PET, it is as specific as we can get.
4:20
The most commonly used radiopharmaceutical is FDG, as you can see.
4:23
It's a GLUT transporter specific evaluation of the diseases, and the second
4:31
most commonly clinically used tracer, we are talking about head and neck
4:34
again, is DOTA TATE PET, and that is not specific but highly selective
4:39
to somatostatin receptor type 2, and both are localized at the cell membrane.
4:44
When a patient receives the radiopharmaceutical, as you can see here,
4:51
after they are transferred into the interstitial space, their interaction
4:57
with the disease states is through transporters or receptors, which is
5:04
highly selective and more specific compared to gadolinium. It's not a passive
5:08
evaluation of what is going on in the patient's body, but it's a more
5:12
active evaluation of what functionally is going on in the patient's body.
5:16
And once again, tracer uptake is not equal to enhancement. After that,
5:23
this is the laundry list of PET tracers that we use,
5:26
either for clinic or for research purposes, but I will show you the
5:31
proven value of glucose analog, which is the FDG PET, more commonly known,
5:38
as well as the DOTA TATE PET. That is a receptor,
5:42
as you can see here, DOTA TATE peptide receptor imaging.
5:47
I just want to put the name here so that we all
5:50
become familiar. I think that is what the feature lies in
5:55
some certain disease states, but not well proven for the head and neck yet.
6:01
As much as FDG and all other imaging tracers that we have so
6:06
far are focusing on the cells, specifically the cancer cells, this tracer,
6:11
namely FAPI, the fibroblast activation protein inhibitor, is focusing on
6:17
the tumor microenvironment. And now we know that
6:20
tumor microenvironment is one of the major drivers of
6:24
treatment response or developing treatment resistance to certain immunotherapy
6:31
agents. So why do we care? Because why do we want to have
6:36
more and more data? Wouldn't the head and neck CT or MR be enough
6:42
for providing the patient the appropriate prognostic stage group, right?
6:48
The only way we can acquire this complementary evaluation after primary
6:53
and nodal disease evaluation by the CT or MRI is PET CT. We
6:59
need PET CT.
© 2024 MRI Online. All Rights Reserved.