Learning Objectives:
Introduction: As therapeutic alternatives and technologies have advanced, the use of non-invasive modes of therapy to avoid surgery has increased. From this perspective the focus of this study was to evaluate the diagnostic benefit of the ADC in conventional echo-planar magnetic resonance imaging (MRI) as a means of differentiating between cholesteatomas and inflammatory lesions.
Methods: We evaluated three patients with suspected temporal-bone cholesteatomas, one infected cholesteatoma and three with inflammatory lesions by using MRI, including standard T2-weighted spin–echo and echo-planar DW/ADC sequences, and computed tomography (CT) as aligned with regions of interest (ROIs) determined in DW imaging. The ADC values in the selected ROIs were calculated by using a 2-point linear regression method (b = 0 and b = 1000 s/mm2). To test the reliability, all measurements were performed twice; the coefficient of correlation was 0.94.
Results: Three of the patients with suspected cholesteatoma and one patient with temporal-lobe abscessation due to temporal-bone inflammatory lesions subsequently underwent surgical confirmation and excision or drainage of their lesions. The ADC values were 0.759–0.915 × 10−3 mm2/s (mean, 0.840 × 10−3 ± 0.0586 mm2/s) for cases of uninfected cholesteatoma, 0.538–0.573 × 10−3 mm2/s (mean, 0.555 × 10−3 ± 0.0141 mm2/s) for infected cholesteatomas, and 0.905–1.272 × 10−3 mm2/s (mean, 1.063 × 10−3 ± 0.123 mm2/s) for inflammatory lesions. These ADC values differed significantly (one-way analysis of variance: F(2,11) = 18.1, P < 0.05).
Conclusions: The ADC value can be used preoperatively to differentiate between temporal-bone cbolesteatomas compared with infectious lesions. However, T2-weighted, FIESTA, or CISS images must be matched carefully to temporal-bone CT scans to accurately define ROIs.
