Fig. 6.

Fungus ball of the left sphenoid sinus (black arrows) in a 61-year-old female patient complaining of headache. CT shows a soft tissue density mass within the left sphenoid sinus with peripheral foci of calcific deposit due to fungal hyphae (black dotted arrows). Complete sinus opacification indicates obstruction of the ipsilateral spheno-ethmoidal drainage recess (a). MRI shows a mass in a completely mucous-filled left sphenoid sinus: the lesion is characterised by intermediate-to-low T1W (b) and T2W (c) SI and intralesional calcified foci with very low SI (black dotted arrows) similar to the air signal. Peripheral rim enhancement is seen on the axial T1W image obtained after gadolinium contrast injection (white arrow, d). The fungus ball shows intralesional areas of low SI on b800 DWI trace (e), and very low ADC values (f) due to the presence of calcifications and paramagnetic metals of fungal hyphae (black dotted arrows). These findings are suggestive for non-invasive fungal infection