Case 41 - Invasive Fungal Sinusitis Imaging Signs
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I wanted to point out two features of aggressive invasive
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fungal sinusitis by mucormycosis or aspergillosis, most commonly,
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and that is the angioinvasive nature of it.
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In this case,
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we have a sphenoid sinus inflammation that was associated
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with absent enhancement of the cavernous sinus.
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Here we have the normal left side with the posterior aspect
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of the cavernous sinus and the lateral aspect of the
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cavernous sinus showing contrast enhancement,
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as well as the internal carotid artery.
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However,
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on the right side you see the carotid artery,
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but you see absence of enhancement
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of the cavernous sinus.
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That suggests that the cavernous sinus may be thrombosed.
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Here on the post gadolinium enhanced scan,
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we have bright signal intensity,
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which is extending onto the tentorial edge
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here at the petroclinoid ligament region.
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This bright signal intensity was actually
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in part due to thrombosis and in part,
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the irregular enhancement that you're seeing here
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is in part due to cavernous sinus thrombosis.
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That's kind of subtle.
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What's not so subtle is that the patient has thrombosis
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of the superior ophthalmic vein.
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Here you see clot in the superior ophthalmic vein with a
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little bit of the venous vasorum of the vein showing
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the clot centrally in the absence of enhancement.
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This is the type of thing that aggressive
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invasive mucor or aspergillus will do,
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and they may do it on the arterial side as well.
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Here is another case of invasive fungal sinusitis that demonstrates
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that feature that I mentioned of absence of contrast enhancement.
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So this is the post gadolinium enhanced scan
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of a patient showing invasive fungal sinusitis.
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And although you see some enhancement in the anterior
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ethmoid air cells, in the posterior ethmoid air cells,
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in the sphenoid sinus,
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you're seeing absence of the normal enhancement
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around the periphery of the mucosa.
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This is because this is necrotic tissue from the aggressive
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fungal sinusitis. So absence of enhancement.
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Some people will call this the so called the black nose
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sign or the dark absence of enhancement sign.
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Here on this patient,
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you see the dark signal intensity of the fungal
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infection affecting the middle turbinate,
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and this middle turbinate on the post gadolinium enhanced scan
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showed absence of enhancement. Here you can see, again,
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a process that has peripheral absence of enhancement
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as opposed to what we would normally expect of an
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inflammatory process, showing enhancement of the mucosa
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of the sinonasal cavity.
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This is aggressive fungal sinusitis.
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Here you can see the patient who has erosion at the skull base
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with eroded bone, and on the MRI scan,
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post gadolinium areas where there is absence of
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enhancement, secondary to the fungal sinusitis.
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So non enhancing tissue, invading outside the sinus,
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often dark on the T2-weighted scan.
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These are the features that would suggest
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aggressive invasive fungal sinusitis.
David M Yousem, MD, MBA
Professor of Radiology, Vice Chairman and Associate Dean
Johns Hopkins University
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