Fusion of MRIs and CT Scans for Surgical Treatment of Cholesteatoma of the Middle Ear in Children

Abstract

Recent developments in imaging techniques have made diffusion-weighted MRI more effective for detecting recurrent cholesteatoma. The major drawback of this technique, however, has been its poor anatomical and spatial discrimination. Fusion imaging using high-resolution CT and diffusion-weighted MRI appears to be a promising technique for both the diagnosis and precise localization of cholesteatomas. It provides useful information for surgical planning and, furthermore, is easy to use in pediatric cases.

Non echo planar, diffusion-weighted magnetic resonance imaging (periodically rotated overlapping parallel lines with enhanced reconstruction sequence) compared with echo planar imaging for the detection of middle-ear cholesteatoma

“…Furthermore, they were the first to fuse non echo planar diffusion-weighted images and high resolution computed tomography (CT) images in order to precisely localise cholesteatomas. 7 Huins All the above-mentioned papers used and/or discussed extensively the half-Fourier acquired single-shot turbo spin-echo diffusion sequence, and, in our opinion, reported similar results and findings to our group, confirming our reported findings. …”

“…Furthermore, they were the first to fuse non echo planar diffusion-weighted images and high resolution computed tomography (CT) images in order to precisely localise cholesteatomas. 7 Huins All the above-mentioned papers used and/or discussed extensively the half-Fourier acquired single-shot turbo spin-echo diffusion sequence, and, in our opinion, reported similar results and findings to our group, confirming our reported findings. Authors' reply Dear Sirs, In reply to De Foer, the primary aim of our study 1 was to attempt to replicate the success obtained by Lehmann et al, 2 in France, obtained with the periodically rotated overlapping parallel lines with enhanced reconstruction sequence.…”

“…Plouin-Gaudon et al, 7 in France, found the half-Fourier acquired single-shot turbo spin-echo sequence to be useful, but only in combination with superimposed CT images. Their series included only 10 patients, and the authors themselves declared that there was a lack of statistical power with which to draw any firm conclusions.…”

Diffusion-Weighted Intensity Magnetic Resonance in the Preoperative Diagnosis of Cholesteatoma

“…Otherwise, only the relief of bone erosion, indicated by a CT scan - in a deductive way - envisages the diagnosis of cholesteatoma. The high-resolution CT of the temporal bones is also important for a preoperative analysis of the extent, the evaluation of the site of the tissue formation, the presence of complications (for example, semicircular lateral canal fistula or erosion of the facial nerve's bony canal), and for the planning of surgery [4,13,21,22]. …”

“…Early studies by William et al [7,8] and Ayache et al [9] have proposed the use of MR ‘with delayed contrast T1-weighted imaging' for its specificity to identify cholesteatoma in the middle ear, but actually the technique that seems to be better to clarify the nature of the lesion is diffusion-weighted intensity MR (DWI-MR), which was introduced in the late 90s for the diagnosis of acute cerebral ischemia [10]. Actually, the DWI-MR shows the Brownian motion [11,12,13,14] of water molecules within the scanned tissue without contrast medium. The speed of the spread movement of water molecules is markedly reduced in cholesteatoma producing a characteristic hyperintensity - obtained by a b factor of 800 or 1,000 s/mm 2 [15] - which is not found in cases where the chronic inflammatory process is represented exclusively from granulation tissue [14,16,17] or a cholesterol granuloma [6].…”