Sinonasal Carcinomas: MR and CT Imaging Features
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Hello everyone.
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Dr. Sidney Levy here.
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I'd like to continue our discussion of the
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diagnosis and staging of Sinonasal Squamous
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Cell Carcinoma by discussing general imaging
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features of this sample case which I've selected.
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So, on the left I have a pre-contrast T1
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weighted axial sequence without fat suppression.
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In the center I have a T2 coronal with fat suppression.
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And on the right, I have a post-
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contrast T1 with fat suppression.
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So, sinonasal tumors may be either well or poorly
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defined masses with irregular or speculated margins.
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In this case, it is a relatively well-defined
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mass with a rather lobulated morphology.
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This particular tumor is originating in
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the nasal cavity, the right nasal cavity.
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There is secondary obstruction of the right maxillary
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sinus, and the T2-weighted images are very important
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for distinguishing tumor from secondary obstruction.
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So firstly, on the T1-weighted imaging, the
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tumor is of similar signal intensity to muscle.
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So, hypointense to intermediate intensity.
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It is slightly hyperintense in
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relation to musculature in this case.
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On T2-weighted imaging, it's important to note that
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often these tumors are not particularly hyperintense.
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They're often of intermediate signal intensity.
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And it's worth comparing them with musculature.
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In this case, it is of intermediate
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signal intensity and it is hyperintense
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with respect to orbital musculature.
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Some people have reported that Sinonasal squamous
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cell carcinoma is relatively hypointense on
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T2 weighted imaging compared with other sinonasal
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malignancies due to its increased cellularity
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and Nucleocytoplasmic ratio.
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T2-weighted imaging is very important for
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distinguishing secondary obstruction of, in this
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case, the maxillary sinus with primary tumor in the
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right nasal cavity, which is relatively hypointense.
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If restricted diffusion has been assessed, then these
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tumors tend to demonstrate mildly restricted diffusion.
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On post-contrast imaging, there is mild to
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moderate diffuse heterogeneous enhancement.
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In cases where the tumor is encroaching on
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the retropharyngeal space, preservation of
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retropharyngeal fat excludes tumor infiltration,
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whereas loss of retropharyngeal fat is an equivocal
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finding which may or may not reflect infiltration.
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With regards to nodal spread, sinonasal malignancy
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tends to involve lymph nodes in levels 2, 4, and 6.
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Sometimes there can also be superior
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spread to retropharyngeal lymph nodes.
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So it's always worth checking those sites.
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And often there is bilateral
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nodal disease when present.
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This particular tumor does
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not demonstrate nodal disease.
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It is important that in addition to MR
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imaging, CT imaging is performed in order
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to supplement one's assessment of the
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status of bone and cortical destruction.
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If PET CT has been performed, these tumors
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are generally FDG avid and intensely avid.
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However, this does not discriminate between
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squamous cell carcinoma and other differential
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diagnoses such as inverted papilloma.
Sidney Levy, PhD, MBBS
Radiologist and Nuclear Medicine Specialist
I-MED
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