Although the concept of nasal valve obstruction（collapse）is gradually spreading in Asia, there is no objective evaluation method. As nasal obstruction evaluated by standard methods is considered normal, there are many patients who have not been evaluated appropriately and their nasal valve obstruction remains untreated. We propose a novel method for measuring nasal valve obstruction using computed tomography（CT）imaging. Two CT images of the nasal cavity are taken；one in the resting position and the other under forced inspiration. We measured the volume difference of the nasal cavity between the images with analysis software, and successfully quantified the difference in 8 patients（average：3.45 ml, range：1.05-8.86 ml）. This examination was relatively reproducible, and also helped to diagnose the position of the nasal valve collapse during operation. This study is the foundation of future studies using this method.
