Radiologic characteristics of sinonasal fungus ball: An analysis of 119 cases

Background: It is important to differentiate sinonasal fungus ball from non-fungal sinusitis and other forms of fungal sinusitis in order to determine the optimal treatment. In particular, a sinonasal fungus ball, a noninvasive fungal sinusitis, can be characterized by radiologic findings before surgery. Purpose: To differentiate a sinonasal fungus ball from other types of sinusitis and determine optimal treatment on the basis of radiologic findings before surgery. Material and Methods: We studied 119 patients with clinically and pathologically proven sinonasal fungus balls. Their condition was evaluated radiologically with contrast-enhanced CT (99 patients), non-contrast CT (18 patients) and/or MRI (17 patients) prior to sinonasal surgery. Results: Calcifications were found in 78 of 116 (67.2%) patients who underwent CT scans for fungus ball. As opposed to non-contrast CT scans, contrast CT scans revealed hyperattenuating fungal ball in 82.8% and enhanced inflamed mucosa in 65.5% of the patients, respectively. On MRI, most sinonasal fungal balls showed iso-or hypointensity on T1-weighted images and marked hypointensity on T2-weighted images. Inflamed mucosal membranes were noted and appeared as hypointense on T1-weighted images (64.7%) and hyperintense on T2-weighted images (88.2%). Conclusion: When there are no calcifications visible on the CT scan, a hyperattenuating fungal ball located in the central area of the sinus with mucosal thickening on enhanced CT scans is an important feature of a non-invasive sinonasal fungus ball. On MRI, a sinonasal fungus ball has typical features of a marked hypointense fungus ball with a hyperintense mucosal membrane in T2-weighted images. A contrastenhanced CT scan or MRI provides sufficient information for the preoperative differentiation of a sinonasal fungus ball from other forms of sinusitis.