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This is a case of a 44-year-old woman

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who had right-sided proptosis.

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As we scroll through the flair imaging of the brain,

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we note that there is a mass identified in the

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right orbit in the retrobulbar space.

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We also see the lateral rectus muscle lateral to the

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lesion, identifying this as an intraconal mass

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in the retrobulbar space.

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So, we are in the intraconal lesion category of disease.

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On the flair scan, we see that it is a well-defined lesion.

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It has some markings of being amidst the

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fat by the frequency shift artifact,

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the chemical shift artifact at the junction with the fat.

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This is the flair scan.

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We then move to look at the orbital

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imaging, and the initial scan here is a coronal

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T1-weighted scan without fat saturation.

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And once again,

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we see a mass which is within the muscle cone,

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still defined by the annulus of Zinn,

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this being the lateral rectus muscle

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and the inferior rectus muscle.

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Once again, the inferior rectus muscle identified

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medial and inferior to the mass

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and the lateral rectus muscle

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just above it.

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In the middle here is the optic nerve.

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So, this is a lesion that is separate from the optic

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nerve within the muscle cone,

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and again, appears to be very well-defined.

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The next thing I would do is to look at the lesion

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with respect to T2-weighted scanning.

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This is a coronal T2-weighted scan with fat

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suppression applied, and we see that the lesion

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has bright signal intensity, in general,

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on the T2-weighted scan.

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Again, inferior rectus muscle, darkened signal intensity

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as muscles are on T2-weighted imaging,

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and the lateral rectus muscle, seen along

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its superior lateral border.

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Separate from the optic nerve and

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the optic nerve sheath complex.

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This lesion does not extend to the orbital apex but is

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in the anterior compartment of the posterior segment.

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We want to see what the enhancement

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characteristics of this mass are.

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This is the coronal post-gadolinium fat-suppressed scan.

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Again, we apply the fat suppression so that way the orbital fat

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is dark, and we see lesions as being outlined against a

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dark background, rather than a bright background

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for gadolinium-enhanced sequences.

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As you can see,

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the mass is showing faint enhancement

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along its inferior aspect.

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Again, we identify the inferior rectus muscle, which enhances

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dramatically, and the lateral rectus muscle,

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which enhances dramatically.

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And these are normal findings,

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as you can see on the contralateral side.

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The optic nerve sheath complex generally does not

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enhance, except for faint enhancement of the sheath.

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So, this mass is showing some enhancement on

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the initial post-gadolinium coronal scan,

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and it remains identified as separate from the optic

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nerve and the muscles within the muscle cone.

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As we scroll more posteriorly,

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we see portions of it showing greater

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enhancement than others.

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The patient then got a post-contrast

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scan through the brain,

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which shows absence of any other lesions,

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so eliminating the possibility that this

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may be a metastasis, for example.

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And then we come to the final sequence,

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which is the post-gadolinium axial scan.

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What we note on the post-gadolinium axial scan is that

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there is slightly greater enhancement of the mass on

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this delayed post-gadolinium enhanced scan than there

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was on the earlier gadolinium-enhanced scan,

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suggesting that this lesion is

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imbibing contrast over time.

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This is a characteristic feature of a venous vascular malformation.

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In the orbit, it's sort of the colloquialism to call these orbital

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hemangiomas, but this is not a tumor,

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this is actually a venous vascular malformation.

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Sometimes known as the orbital cavernous venous malformation,

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but it should not be considered a tumor.

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This is the most common of the intraconal masses.

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And as I said earlier,

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it generally occurs in middle-aged women,

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and it may enlarge over time.