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In this video we are going

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to discuss neuroendocrine tumors and PET ct.

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I'm gonna give you some background on neuroendocrine tumors.

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We're gonna discuss the role of Dotatate PET ct.

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We're gonna discuss, uh, interpretation.

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Uh, we will review some cases

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and we'll touch on targeted therapy.

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So narrow endocrine tumors are classified into

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different degrees based on the metallic count

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and the level of KI 67 index,

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which is an index of cellular proliferation.

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This is for mid gut.

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The pulmonary carcinoids are classified

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based on the ME mitotic count and presence of necrosis.

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So these are the grades

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of neuroendocrine tumors based on the KI 67

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and I'm showing you two categories.

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One is well differentiated

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and then uh, poorly differentiated.

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And this is important because each tumor

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type will be best seen

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with either a dotatate tracer or an FEG.

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The grades one to three that have these different degrees

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of K 67 index are best seen

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with dotatate tracers,

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but once they are poorly differentiated,

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they lose their ability to behave as a neuroendocrine tumor

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and become very aggressive.

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And therefore DOTA tracers like dotatate would not be ideal

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to identify these tumors.

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And we will offer FDG, which is not specific,

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but is sensitive in detecting malignancy.

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So it is important to keep this classification in mind

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to be able to first select what tracer

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to use if you knew what grade the tumor was.

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And second, if you didn't know, you would be able

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to then recommend one

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or the other if your pet is not extremely positive,

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but there's for instance, CT abnormalities

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that cannot be explained with the tracer.

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Also, it's important to know that tumors are heterogeneous.

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So sometimes we might find that tumor is not

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all dotatate AVID or FDG avid.

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It may have a combination.

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So sometimes we actually have to use both tracers

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to do a full staging.

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So what's the role of Dotatate PET ct?

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This is the most commonly used tracer.

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First, when there is a clinical suspicion

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for neuroendocrine tumor or you have abnormal biomarkers

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or imaging findings that are very specific

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or you have a histopathology sample

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that tells you there's a neuroendocrine tumor,

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if it's a grade one to three, as we mentioned earlier,

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you would move to offer a dote pity.

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And the staging is crucial

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because we can help determine if the patient is a surgery

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candidate or not.

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As surgery is the only curative approach

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for neuroendocrine tumors.

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So information that we want to provide

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with the will be staging

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PET can help in another staging

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as we can detect a disease in very small lymph nodes.

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Remember that historically with morphologic imaging,

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this would be CT or MRI.

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We need a size criteria in order

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to call a lymph node abnormally enlarged,

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which would be greater than one centimeter.

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But with molecular imaging, we're able to detect disease

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even in smaller lymph nodes.

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And therefore, uh, dotatate PET is crucial in

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staging these patients.

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Also, we can detect, uh, small metastasis, uh,

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most commonly going to the liver, peritoneum lung

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and bone that you will see in many times

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don't have a CT correlate.

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And again, this is the advantage of molecular imaging.

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We also use DOTA data in cases

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of recurrence when there is a suspicion either clinical

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or from lab or imaging.

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And sometimes we know

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that there is metastatic neuroendocrine tumor,

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but we don't know which is the primary.

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So DOTATATE can help guide the identification

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of the primary tumor.

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As I mentioned earlier, there's tumor heterogeneity.

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And so combining FDG, PET

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and DOTE PET can give us a better understanding of the real

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extent of disease and behavior.

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And this is an example from the literature

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in which we see on the left an FDG pit

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that shows multiple areas of increased tracer uptake

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that are abnormally in the liver and in the abdomen.

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And on the right we have, uh, gallium dotatate

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pit in which we see also abnormal

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tracer uptake in the liver more extensively than the seen on

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the FDG, but some areas where there is do data uptake

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that is not FDG avid, for instance, at the hepatic dome

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reflecting that heterogeneity

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and showing us with imaging the mix of

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well differentiated neuroendocrine

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and also poorly differentiated disease within

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The same patient.

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This is another example from the literature

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that shows different degrees of these mix

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or these heterogeneous behavior.

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On the first case, we see

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that this patient has dotatate avid disease

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and is FDG negative.

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Therefore it's all well differentiated

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neuroendocrine disease.

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The patient on the center has positive findings

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with both tracers

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and so it's heterogeneous in showing us both well

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differentiated and poorly differentiated.

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And the third case shows negative DOTA take pet,

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but extremely positive disease in the liver

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indicating a highly aggressive

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and poorly differentiated carcinoma.

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So moving on to interpretation,

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we have reviewed what's the normal distribution

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of this trace area in another section.

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And so now we are going to assess

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how do we describe these findings.

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And there is a scoring system that is visual

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that is called theran, a scoring system.

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And it's basically a comparison

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of the uptake in the areas of abnormality to liver

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and a spleen.

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You can use that, uh, in your report to

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describe when things are abnormal and how abnormal they are.

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I personally don't use the scoring numbers.

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I do it qualitatively rather than quantitatively,

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but both are appropriate.

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One of the things we can offer

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with neuroendocrine tumors is targeted therapy.

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In this case, we can pair the dotatate with a radionuclide

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that delivers radiation directly to the cells

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with a beta particle that it's uh, lutetium 1 77 to be able

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to treat these patients in a targeted way

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rather than diffusely as the tracer would only concentrate

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in areas of disease.

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This therapy has been approved by the FDA, uh,

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since 2018

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and is currently used for

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multiple neuroendocrine tumors including rectum, pancreas,

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small bowel and stomach.

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The clinical trial that allowed us

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to treat these patients was net one,

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which was a phase three, which demonstrated

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that it was highly effective in controlling advanced

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metastatic and inoperable disease

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and it improved progression-free survival

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and quality of life.

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In order to select these patients for therapy, we have

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to first prove that the disease is a highly

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Dotatate avid, and

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therefore dotatate PET CT in these cases will be a

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requirement before treating.

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In those cases where we showed heterogeneous disease,

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both dotatate, AVID

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and FDG avid, those would not be ideal candidates

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for this therapy as we would only be partially treating

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disease.