Fig. 3From: A novel anatomical classification of the frontal sinus: can it be useful in clinical approach to frontal sinusitis?Coronal (a, b) and sagittal (c) computed tomography sections demonstrating mucosal thickening (red arrows), retention cyst/ polyp (blue arrow), and fluid collection (purple arrow) which are taken as the criteria of the presence of frontal sinusitisBack to article page