Proposed computed tomography severity index for the evaluation of invasive fungal sinusitis: Preliminary results

Figure 1 Flowchart to depict the methodology of the study. IFS: Invasive fungal sinusitis; CT: Computed tomography; PNS: Paranasal sinuses; CECT: Contrast-enhanced computed tomography; NCCT: Non-contrast computed tomography.

Figure 2 Mild disease with computed tomography severity index 2 (67-year-old male, coronavirus disease 2019 positive with mild headache and right-sided facial pain). The patient was a known diabetic with an HbA1C of 8.5. Microbiological evaluation revealed both Aspergillus sp. and Rhizopus sp. A-C: Axial computed tomography (CT) images show minimal soft tissue within the left ethmoid sinus (A) and right maxillary sinus infiltrating the adjacent right posterior retroantral fat (B). The bilateral eye globes and orbits are normal. There is e/o erosion in the anterior maxillary wall with soft tissue infiltrating the preantral space (C); D-F: Coronal bone window CT images. Figure D shows bone erosion in the anterior maxilla (arrow). There is evidence of bilateral disease with mild mucosal disease in the right maxillary sinus (dotted arrow in F) and left ethmoid sinus (dotted arrow in E) with mucosal thickening of the right inferior turbinate (arrow in F). The hard palate is intact (arrow in E). The total summated CT severity index for this case is 2 - mild disease (1 point for involvement of right maxillary sinus and ethmoid sinus, 1 point for the involvement of anterior and posterior periantral fat). The patient was given intravenous amphotericin to which the patient responded well. Repeat imaging was not done in this case.

Figure 3 Severe disease with computed tomography severity index 18 (50-year-old male, coronavirus disease 2019 positive with periorbital pain, left eye vision loss and cranial nerve palsies). The patient was a known diabetic with an HbA1C of 12.2. Microbiological evaluation revealed Rhizopus species. A-C: Axial contrast-enhanced computed tomography (CT) images show bilateral disease involving bilateral maxillary sinuses and nasal cavities (asterisk in A) with involvement of right posterior antral fat and pterygopalatine fossa (PPF; arrow in A). There is soft tissue infiltration in the left orbital fat extending to the left inferior orbital fissure (IOF; asterisk in B) with evidence of thickening of the left globe wall along with tenting of the posterior pole of the globe giving a classical guitar pick appearance suggesting the involvement of the left globe (arrow in C); D-F: Coronal CT images show erosion of the hard palate (arrow in D), fat stranding in the left orbit and thickening and irregularity of the left optic nerve (arrow in E). There is evidence of soft tissue infiltration in the left cavernous sinus (dotted arrow in F) with focal narrowing of the cavernous segment of left internal carotid artery (ICA; arrow in F). The total summated computed tomography severity index, in this case, is 18 (1 point each for paranasal sinuses and nasal cavity involvement, 2 points for significant bilateral disease, 1 point for the involvement of posterior antral fat, 1 point for hard palate erosion, 1 point for orbital soft tissue involvement, 2 for PPF/IOF involvement, 3 points for globe involvement, 3 points for cavernous sinus involvement and 3 points for ICA narrowing). Left exenteration was done due to extensive disease and intravenous amphotericin was given. Clinically, the patient did not respond well to the treatment, and repeat imaging was done 10 weeks later.

Figure 4 Repeat imaging after 10 weeks of patient in Figure 3 (known case of rhinoorbitocerebral mucormycosis with severe disease and post left exenteration). A and B: Axial contrast-enhanced computed tomography images (A and B) reveal soft tissue infiltrating the right posterior antral space (arrow in A) and soft tissue in the left orbit with contiguous extension to the left orbital apex and left cavernous sinus (arrow in B). Left post-exenteration status can be seen; C and D: Coronal images show soft tissue in the left cavernous sinus with the non-opacified cavernous segment of the left internal carotid artery suggesting its occlusion (arrow in C). There is also evidence of maxillary alveolus destruction and sequestrum formation (arrow in D). This repeat imaging shows radiological worsening post-treatment (non-responder).

Figure 5 Receiver operating characteristic curve for computed tomography severity score and response assessment shows that the cut-off value for computed tomography severity index of 11 had a sensitivity of 78. 26% and a specificity of 95.35% to predict response assessment. ROC: Receiver operating characteristic.