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Hello, everyone.

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Sidney Levy here, continuing our discussion of the

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diagnosis and staging of laryngeal squamous cell malignancy.

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I have an example case here of a transglottic

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laryngeal squamous cell carcinoma, which I'd

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like to use to demonstrate the principles

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of how we identify and stage these tumors.

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So a transglottic malignancy is by definition

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one, um, which includes the glottis as well

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as the adjacent supraglottis and subglottis.

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And many laryngeal tumors do involve more than one subsite.

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So in general, what are the MR imaging features

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for laryngeal squamous cell malignancy?

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In this example case, I have a pre-contrast T1 weighted

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sequence without fat suppression, a pre-contrast T2

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weighted sequence with fat suppression, and a post

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contrast T1 weighted sequence with fat suppression.

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The tumor, I will draw it for you,

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so that we can understand where we are.

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This is the tumor here, the top portion of it.

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That's quite a large tumor, and it is crossing the midline.

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So what are the things that we look

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for when we assess these lesions?

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On T1, they are normally hypointense or

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of similar intensity to adjacent musculature.

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In this case, this one is relatively hypointense.

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On T2 weighted imaging, they are often T2

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intermediate, so not necessarily very hyperintense,

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but similar to this case of an

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intermediate signal intensity.

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On post-contrast imaging, there is a variable

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enhancement which can be heterogeneous,

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as in this case, or relatively homogeneous.

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So that's the tumor itself.

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But whenever we have a laryngeal tumor, we need to make

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an assessment of the status of the laryngeal cartilages.

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So, as we discussed in our anatomy section, we have thyroid

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cartilage, cricoid cartilage, and arytenoid cartilage.

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And in this case, I'm at the level of the thyroid cartilage.

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So this tumor is involving thyroid cartilage.

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And I want to try and demonstrate for you

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the features which make us confident of

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this and what we need to pay attention to.

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So on T1 weighted imaging, we're looking for

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infiltration of cartilage and destruction of

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the inner and outer cortices of the cartilage.

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So we have some normal thyroid cartilage here.

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However, beyond this level, it is eroded and

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it is diffusely T1 hypointense and we have

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lost the normal cortex of the cartilage.

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It has all become indistinct at this level.

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A bit more distinct here and then heading

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into normal appearing cartilage at the back.

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So what can we take away from that?

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We are looking for T1 hypointensity and loss

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of the normal cortical margins of cartilage,

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all suggestive of either destruction or infiltration.

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On T2 weighted imaging, we are looking for edema at

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relative T2 hyperintensity of the cartilage, which would

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normally be quite hypointense, as well as destruction.

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So here, for instance, we have abnormal T2 hyperintensity

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of the cartilage, whereas here, it is destroyed.

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On the other side, and a little bit further

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up, we can see some more normal appearing

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cartilage at a higher level, up to about there.

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This is all still quite abnormal too.

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On post-contrast imaging, we are looking for

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abnormal enhancement of the cartilage, which

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should be contiguous or closely abutting tumor.

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So in summary, what have we looked at so far?

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We have looked at the general features of

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laryngeal squamous cell malignancy, and we have discussed

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how cartilage may appear on MRI for us to be able

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to say whether it is involved by tumor or not.

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The last thing that's important to say

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in this section is that CT is a very

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important adjunct for cartilage assessment

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as it helps to define the cortex of cartilage in

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ways that can sometimes be difficult with MRI.

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And if we are going to do CT in this region,

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remember to do it in quiet respiration.

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So, we're looking for edema of

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cartilage on T2 weighted imaging.

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But edema on its own is not

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diagnostic of cartilage involvement.

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It reflects perichondritis, if you like.

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However, if the signal intensity on T2 weighted imaging, or

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the enhancement of cartilage on post-contrast T1 weighted

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imaging, is the same as adjacent tumor, the same signal

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intensity, invasion is more likely rather than less likely.

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Ultimately, it is the presence or absence of cortical

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destruction or loss of cortical integrity, which is

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the most specific sign for cartilage involvement.