Artifactual thickening of the sinus walls on computed tomography: A phantom model and clinical study

Measuring sinus wall thickness on computed tomography may be important for distinguishing between acute and chronic inflammation of the paranasal sinu ses or in cases of a suspected neoplasm. The objective of this study was to investigate the effects of opacified and aerated sinuses on the appearance of sinus wall thickness. A phantom model consisting of a skull half-immers ed in water was scanned, and various slice thicknesses and different window s were used. The sinus walls of the water-immersed side appeared to be thic ker than those of the aerated side. Bone windows did not completely elimina te this partial volume effect. It was concluded that comparison between a f luid- or tissue-filled sinus and an air-filled counterpart is not accurate enough for evaluating sinus wall thickness. Bone windows do not completely eliminate the artifactual thickening of the bony wall of a filled sinus.