What is the role of imaging studies in the diagnosis of fungal sinusitis?

Updated: Mar 17, 2020
  • Author: Hassan H Ramadan, MD, MSc; Chief Editor: Arlen D Meyers, MD, MBA  more...
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CT scanning of the paranasal sinuses in the coronal views is essential in the evaluation of patients in whom fungal sinusitis is suspected. [5, 6]  Middlebrooks et al devised a seven-variable, CT scan–based diagnostic model for acute invasive fungal rhinosinusitis. They reported that an abnormality associated with one of the model’s variables—which consist of periantral fat, bone dehiscence, orbital invasion, septal ulceration, the pterygopalatine fossa, the nasolacrimal duct, and the lacrimal sac—has a positive predictive value of 87%, a negative predictive value of 95%, a sensitivity of 95%, and a specificity of 86%, while the involvement of two variables gives the model a specificity of 100% and a positive predictive value of 100%. [13]

While intralesional hyperdensity on CT scan can be used in the detection of a maxillary sinus fungus ball, zinc deprivation can lead to the absence of this finding. However, a retrospective study by Cha et al indicated that other CT-scan characteristics can be used to help identify such lesions, including a “fuzzy appearance and maxillary sinus full haziness with mass effect.” [14]

Magnetic resonance imaging (MRI) with enhancement may be helpful in assessing patients with allergic fungal sinusitis and in patients in whom invasive fungal sinusitis is suspected. [6]  MRI may show low signal intensity, suggesting a fungal process versus a solid mass in allergic fungal sinusitis. It is also helpful in evaluating CNS spread in invasive fungal sinusitis.

A study by Kim et al indicated that T1-weighted images (T1WI) in MRI can be used in combination with T2WI to identify the presence of fungus balls in the paranasal sinuses. The investigators state that fungus balls “can be suggested by the presence of the hyper-signal intensity portions in the fungal mass on T1WI in conjunction with dark-signal lesions surrounded by high-signal, hypertrophic mucosal walls in paranasal sinuses on T2WI.” [15]


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