S204 – Postoperative Residual Cholesteatoma: Value of MR Imaging

Abstract

Objectives This study was carried out to evaluate the utility of diffusion-weighted imaging (DWI) and contrast-enhanced MR imaging (CE-MRI) for the detection of postoperative residual cholesteatoma in cases where computed tomographic (CT) findings were not conclusive. Methods 14 ears from 13 patients, who had undergone canal wall-up tympanoplasty for cholesteatoma and nonspecific opacity images on postoperative follow-up CT, underwent MR imaging before revision surgery. T1WI, T2WI DWI (using b-factors of 0 and 800 sec/mm2) and CE-MRI were performed using a 1.5-T MR unit. MR imaging examination was generally completed within 30 min. In all cases, imaging findings were compared with second- or third-look operative findings. Results MR imaging depicted 9 out of 10 residual cholesteatomas (sensitivity, 90.0%). In a remaining (false-negative) case, a 3-mm cholesteatoma pearl that was encircled by granulation tissue was not depicted. There were no false-positive cases (specificity, 100%). The positive predictive value and negative predicitive value were 100% and 75%, respectively. DWI showed cholesteatoma high signal intensity in peculiarity. However, the spatial resolution was low and artifacts appeared at the base of skull in DWI. In the case with a small cholesteatoma in the dura mater, CE-MRI was effective. The minimum size of the cholesteatomas detected by the MR imaging including DWI was 4 mm. Conclusions When postoperative CT is not conclusive, DWI combined with CE-MRI is a valuable technique for the detection of residual cholesteatoma.