Apparent diffusion coefficients for detection of postoperative middle ear cholesteatoma on non-echo-planar diffusionweighted images

摘要

Purpose: To determine whether there is a difference between the apparent diffusion coefficients (ADCs) of postoperative middle ear cleft cholesteatoma and noncholesteatomatous tissue on half-Fourier acquisition single-shot turbo spin-echo diffusionweighted (DW) images and to determine, with interobserver agreement, a predictive accuracy for diagnosis of postoperative middle ear cleft cholesteatoma. Materials and Methods: Patients who underwent DW magnetic resonance (MR) examination before repeat explorative surgery for postoperative cholesteatoma were included in this study. There were 72 patient episodes and 56 patients. DW MR images were acquired with b values 0 and 1000 sec/mm2 and 2-mm section thicknesses. Two observers assessed images qualitatively for presence of cholesteatoma and recorded ADCs. Surgery with histologic confirmation established final diagnosis of abnormal middle ear cleft soft tissue. ADCs between cholesteatoma and noncholesteatomatous tissue were compared with Mann-Whitney test. Effects of ADCs and confidence intervals to indicate presence of cholesteatoma were examined by using receiver operating characteristic (ROC) curve analysis, logistic regression analysis, and interobserver agreement. Results: Forty-six patients had cholesteatoma and 25 patients did not; sensitivity and specificity were 0.91 and 0.88, respectively, for the qualitative diagnosis of postoperative cholesteatoma by using a five-point confidence scale. ADC of cholesteatoma (median, 707 3 1026 mm2/sec; interquartile range, 539-858 × 10-6mm2/sec; P .001) was significantly lower than that of noncholesteatomatous tissue (median, 1849 × 10-6mm2/sec; interquartile range, 1574-1982 × 10-6mm2/sec; P .001). There was good accuracy (area under the ROC curve, 0.97) and interobserver agreement for detecting postoperative cholesteatoma with ADC threshold less than 1300 × 10-6mm2/sec. Conclusion: The ADC value of postoperative middle ear cleft cholesteatoma is significantly lower than that of noncholesteatomatous tissue and has good accuracy for detecting cholesteatoma.