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AJNR - American Journal of Neuroradiology

Published ahead of print on March 25, 2009
doi: 10.3174/ajnr.A1558

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CT Grading of Otosclerosis

T.C. Lee^a, R.I. Aviv^a, J.M. Chen^b, J.M. Nedzelski^b, A.J. Fox^a and S.P. Symons^a

^a Division of Neuroradiology, Sunnybrook Health Sciences Centre, University of Toronto, Toronto, Ontario, Canada
^b Department of Medical Imaging, and Department of Otolaryngology–Head and Neck Surgery, Sunnybrook Health Sciences Centre, University of Toronto, Toronto, Ontario, Canada

View larger version (125K): [in this window] [in a new window]   Fig 1. Axial CT images of the petrous bone in patients with otosclerosis. Grade 0: normal. Grade 1: small lucent lesion at the fissula ante fenestram. Grade 2A: sclerosis and narrowing of the basal turn (also has spongiotic fenestral disease). Grade 2B: lucent lesion extending from the fissula ante fenestram to the middle turn of the cochlea. Grade 2C: patchy lucency around the lateral aspect of basal, middle, and apical turns of the cochlea, the medial aspect of the cochlea appears spared. Grade 3: severe, confluent lucency around the cochlea.

View larger version (64K): [in this window] [in a new window]   Fig 2. Disagreement between grade 1 vs grade 2B. Grade 1: there is a lucent lesion in the cochlear promontory with preservation of the adjacent middle turn otic capsule. Grade 2B: there is a lucent lesion in the cochlear promontory, with clear extension to the adjacent otic capsule of the middle turn. Grade 1 vs grade 2B: there is a lucent lesion in the cochlear promontory with debatable extension to the otic capsule of the middle turn and this was graded as 1 by the first neuroradiologist and 2B by the second neuroradiologist.

View larger version (10K): [in this window] [in a new window]   Fig 3. Grades of otosclerosis. The distribution of grades 0 through 3 among the 149 agreements.