Contemporary Non–Echo-planar Diffusion-weighted Imaging of Middle Ear Cholesteatomas

Abstract

Middle ear cholesteatoma is a common inflammatory disease that requires surgery due to potentially serious intracranial complications. Diagnosis of cholesteatoma is mainly clinical, with computed tomography (CT) used to evaluate disease extension before surgery. Certain patterns of bone erosion are specific, but CT attenuation does not allow differentiation from other inflammatory middle ear diseases. With its high tissue discrimination and contrast resolution, magnetic resonance imaging is valuable in diagnosis of cholesteatomas. Absent enhancement at delayed postcontrast imaging has been used for diagnosis. Diffusion-weighted imaging (DWI) is highly specific due to the high keratin content of cholesteatomas. New non-echo-planar DWI sequences, such as periodically rotated overlapping parallel lines with enhanced reconstruction, are superior to conventional echo-planar DWI, since they minimize susceptibility artifacts at the skull base and increase sensitivity for detection of lesions as small as 2 mm. This technique is indicated when clinical diagnosis is difficult and high tissue specificity is necessary, as in congenital, temporal bone, or atypical acquired middle ear cholesteatomas and residual or recurrent disease after surgery. Non-echo-planar DWI has been proposed for screening of postsurgical (residual or recurrent) cholesteatomas, thus obviating many second-look revision surgeries, especially after more conservative canal wall up surgery. ©

Detection of cholesteatoma: High-resolution DWI using RS-EPI and parallel imaging at 3 tesla

“…Similarly, a certain cut-off value could not be indicated in our study as well. However, our findings are compatible with the literature data [3,16,18,[22][23][24].…”

“…Usually, mural cholesteatomas are not visible on DWI [18]. We detected relatively minimal susceptibility related distortion (especially on coronal plane images) of the bone and air transition zone in some patients although it was significantly less on RS-EPI images when compared with the SS-EPI technique.…”

“…Hence, RS-EPI technique can supply a more effective evaluation for cholesteatomas. Although the sensitivity of SS-EPI technique is relatively high for detecting the lesions more than 5 mm, the effectiveness of this technique is low in detecting lesions that are less than 5 mm [18]. We could not visualize the lesion clearly and could not measure ADC value in coronal plane of SS-EPI in three patients and in axial plane of SS-EPI in one patient among our patient group.…”

“…Delayed phase post-contrast T1 W imaging (45 minutes after intravenous gadolinium administration) has some disadvantages including increased cost, the scanning time and risk of nephrogenic systemic fibrosis [14,17]. In addition, some false positive results could be seen at delayed phase post-contrast T1 W imaging such as retained inflammatory secretions, which may simulate a nonenhancing cholesteatoma [18].…”

MRI Sequences in Head & Neck Radiology – State of the Art

“…The k-space data are acquired in the form of rotating sections (blades). The resulting oversampling of the central k-space leads to an improved signal-to-noise ratio (SNR) and to the reduction of motion and susceptibility artifacts [41,43,44]. RESOLVE DWI is a new approach for obtaining DWI images with high quality, delivering sharp images at high spatial resolution and reduced slice thickness.…”