Diffusion-weighted MR imaging in postoperative follow-up: Reliability for detection of recurrent cholesteatoma
Introduction
Cholesteatoma is an epidermoid cyst containing desquamating stratified squamous epithelium that grows progressively as the epithelial debris increase. The process destroys the neighboring bony structures and the only form of treatment is surgical removal. Patient follow-up routine involves computed tomography (CT) to evaluate the middle ear aeration. If the cavity formed after surgery is filled with soft tissue, CT has limitations as the soft-tissue mass can be caused by recurrent cholesteatoma, granulation, or fibrous tissue, which are common after surgery, or both cholesteatoma and granulation tissue. Differential diagnosis is important since further surgery is necessary if recurrent cholesteatoma is diagnosed, but not if granulation tissue is detected.
It has been shown that magnetic resonance (MR) imaging can be useful in the differentiation of recurrent cholesteatoma from granulation tissue with the use of delayed contrast enhanced T1-weighted sequences [1], [2], [3], [4]. Diffusion-weighted MR imaging (DWI) has also been shown to be useful in the detection of recurrent cholesteatoma [5], [6]. This study was carried out to find out if DWI alone can be a reliable alternative to CT without any use of contrast agent for follow-up of postoperative patients in detecting recurrent cholesteatoma.
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Materials and methods
We evaluated 26 consecutive patients (16 females and 10 males) with a mean age of 39 years (16–63 years) who had undergone mastoidectomy for the cholesteatoma of the middle ear. All patients with ear discharge reporting for routine follow-up CT after mastoidectomy between August 2007 and September 2008 were examined with MR, if there was loss of middle ear aeration on CT examination. The patients were briefed about the study and informed consent was obtained from all patients.
MR imaging was
Results
Both observers’ interpretation of T2W images was parallel with the loss of aeration detected on CT for all 26 patients. There were no different opinions between the two radiologists about the diagnosis of either the loss of aeration or DWI signal changes in any of the patients.
Of the 26 patients examined, 14 had no high signal intensity on DWI and the loss of aeration in the middle ear was not evaluated as recurrent cholesteatoma. This finding was verified after surgery in all 14 patients. Thus
Discussion
Cholesteatomas are collections of keratin exfoliates growing over time in a sac of stratified squamous epithelium [7]. This characteristic is responsible for the lack of enhancement of the lesion with contrast media. The most important and frequent differential diagnosis in the postoperative evaluation of patients is granulation tissue growth after surgery. This entity has a late phase contrast enhancement due to its fibrous structure [4]. The use of contrast and the necessity of time delay for
Conclusions
In conclusion, we think in light of our own experience and other studies that the use of diffusion-weighted imaging for suspected recurrent cholesteatoma is a valuable tool to cut costs and prevent unnecessary second-look surgeries. As further studies comparing this technique with contrast enhanced sequences are made, it can become the MR sequence of choice to differentiate recurrent cholesteatoma from other causes of loss of aeration in patients with mastoidectomy.
Conflict of interest statement
There is no conflict of interest.
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