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Background and Purpose: Focal low-attenuation outpouching or diverticulum at the anterolateral internal auditory canal is an uncommon finding on CT of the temporal bone. This finding has been described as cavitary otosclerosis in small case reports and histology series. The purpose of this study was to establish the prevalence of internal auditory canal diverticulum and its association with classic imaging findings of otosclerosis and/or hearing loss., Materials and Methods: Temporal bone CT scans of 807 patients, obtained between January 2013 and January 2016, were retrospectively reviewed to identify internal auditory canal diverticula and/or classic imaging findings of otosclerosis. Clinical evaluations for hearing loss were reviewed for patients with internal auditory canal diverticula and/or otosclerosis., Results: Internal auditory canal diverticula were found in 43 patients (5%); classic otosclerosis, in 39 patients (5%); and both findings, in 7 patients (1%). Most temporal bones with only findings of internal auditory canal diverticula (91%) demonstrated hearing loss, with 63% of this group demonstrating sensorineural hearing loss. The hearing loss classification distribution was significantly different ( P < .01) from that in the classic otosclerosis group and in the group with both diverticula and otosclerosis., Conclusions: Internal auditory canal diverticula are not uncommon on CT examinations of the temporal bone and most commonly occur without classic imaging findings of otosclerosis. These lesions are associated with sensorineural hearing loss, and referral for hearing evaluation may be appropriate when present., (© 2017 by American Journal of Neuroradiology.)

Background and Purpose: Lumbar discitis-osteomyelitis has imaging characteristics than can overlap with noninfectious causes of back pain. Our aim was to determine the added accuracy of psoas musculature T2 hyperintensity (imaging psoas sign) in the MR imaging diagnosis of lumbar discitis-osteomyelitis., Materials and Methods: This retrospective case-control study evaluated lumbar spine MR imaging examinations, during a 30-month period, that were requested for the evaluation of discitis-osteomyelitis. Of this pool, 50 age-matched control patients were compared with 51 biopsy-proved or clinically diagnosed patients with discitis-osteomyelitis. Two reviewers, blinded to the clinical information, assessed the randomly organized MR imaging examinations for abnormalities of the psoas musculature, vertebral bodies, discs, and epidural space., Results: Psoas T2 hyperintensity demonstrated a high sensitivity (92.1%; 95% CI, 80%-97.4%) and specificity (92%; 95% CI, 80%-97.4%), high positive likelihood ratio (11.5; 95% CI, 4.5-29.6), low negative likelihood ratio (0.09; 95% CI, 0.03-0.20), and individual area under the receiver operating characteristic curve of 0.92; 95% CI, 0.87-0.97. Identification of psoas T2 abnormality significantly improved (P = .02) the diagnostic accuracy of discitis-osteomyelitis in noncontrast examinations from an area under the receiver operator characteristic curve of the established variables (vertebral body T2 and T1 signal, endplate integrity, disc T2 signal, and disc height) from 0.93 (95% CI, 0.88-0.98) to 0.98 (95% CI, 0.96-1.0). Psoas T2 abnormalities also had the highest interobserver reliability with a κ coefficient of 0.78 (substantial agreement)., Conclusions: Psoas T2 hyperintensity, the imaging psoas sign, is highly correlated with discitis-osteomyelitis. T2 hyperintensity in the psoas musculature, particularly when there is clinical suspicion of spinal infection, improves the diagnostic accuracy of discitis-osteomyelitis compared with routine noncontrast variables alone., (© 2016 by American Journal of Neuroradiology.)