Review ArticleDiffusion-weighted magnetic resonance imaging in the detection of residual and recurrent cholesteatoma in children: A systematic review and meta-analysis
Introduction
Cholesteatoma is an abnormal growth of squamous epithelium which may be located in the middle ear, mastoid process of the temporal bone, petrous apex, or other areas [1]. Both the congenital and acquired forms of cholesteatoma occur in children. The disease is considered to be more aggressive in children compared to adults leading to a more extensive disease on presentation, increased chance of sequelae, and higher rates of residual or recurrent lesions [[2], [3], [4]].
Surgical removal is required in all cases to eradicate the disease. Transcanal endoscopic approaches have emerged as a useful means of cholesteatoma eradication, offering superior access to the tympanic cavity in a minimally invasive manner. However, transcanal endoscopic approaches provide poor access to the mastoid cavity proper [5]. If a mastoidectomy is required, a canal wall up approach is typically preferred in children as it preserves anatomy, has fewer complications associated with water, and allows for comfortable fitting of a hearing aid post-operatively, when compared to canal wall down methods [6,7]. However, due to the higher rate of recurrence and the inability to visualize the mastoid cavity postoperatively, canal wall up and transcanal endoscopic surgery frequently necessitate a second-look operation [8,9]. Second-look surgery is not without its drawbacks, including the cost of surgery, anesthesia-related risks, and challenges associated with operating in a previously altered anatomical field. As a result, various imaging modalities have been explored in an attempt to mitigate the need for second-look cholesteatoma surgery, as well as to provide an effective method of monitoring recurrence.
High-resolution Computed Tomography (CT) of the petrous temporal bones is routinely performed in the pre-operative assessment of cholesteatoma patients to determine the extent of disease, the integrity of adjacent structures, and the potential complications of surgery. However, CT remains limited in its ability to distinguish residual and/or recurrent cholesteatoma from cholesterol granulomas, granulation tissue, and fibrosis in the post-operative monitoring phase [10,11]. More recently, diffusion weighted magnetic resonance imaging (DW-MRI) has gained popularity as a promising imaging modality to detect cholesteatomas. Typically, in primary surgery, the diagnosis of cholesteatoma is evident and DW-MRI is used to confirm the extent of rather than presence of cholesteatoma. Its use in the post-operative period is of additional clinical importance given its potential role as a non-invasive alternative to planned second-look surgery.
DW-MRI can largely be divided into the more traditional, widely available echo-planar imaging (EPI), and the newer non-EPI sequences, which utilise single shot (SS) or multi-shot (MS) techniques. Non-EPI DW-MRI has been demonstrated to provide better overall spatial resolution and diagnostic performance when compared to EPI DW-MRI, as it is not vulnerable to the susceptibility artefacts found in the EPI technique [10,12,13].
Multiple studies, including systematic reviews and meta-analyses, have investigated the utility of DW-MRI in the detection of recurrent and residual cholesteatoma in both adult and mixed adult and pediatric populations following primary typanomastoid surgery. A recent meta-analysis with a predominantly adult cohort noted a high sensitivity (93%, 95%CI 84%–97%) and high specificity (91%, 95%CI 85%–94%) for non-EPI DW-MRI following primary cholesteatoma surgery [14]. However, to our knowledge, no reviews have examined the performance of DW-MRI following primary cholesteatoma surgery exclusively in pediatric patients. Directly extrapolating findings of meta-analyses with a majority or entirety of adult cases to pediatric patients is challenging given the often more aggressive nature of the disease in children. As such, this study aimed to specifically examine the performance of DW-MRI in detecting recurrent or residual disease following primary cholesteatoma surgery in children.
Section snippets
Study design
A systematic review and meta-analysis was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines.
Search strategy
A search of the literature was conducted on the 24th of January 2018 using the following databases from their date of inception: MEDLINE, PubMed, Embase, Cochrane Library, Web of Science. The following search terms were used:
- 1.
MRI OR magnetic resonance imaging OR diffusion-weighted OR DW-MRI OR diffusion MRI OR DWMRI OR diffusion imaging
Results
An initial search identified 585 articles after duplicates were removed. The titles were screened for appropriateness, leaving 102 full-text articles to be assessed for eligibility against the inclusion and exclusion criteria (Fig. 1). A total of ten articles met the criteria for inclusion in qualitative synthesis and meta-analysis [[18], [19], [20], [21], [22], [23], [24], [25], [26], [27]]. A summary of the ten articles is included in Table 3.
Nine of the included articles were prospective
Discussion
This study set out to investigate the performance of DW-MRI in the postoperative monitoring of children following primary cholesteatoma surgery. Meta-analysis indicated that non-EPI DW-MRI appears to be a useful diagnostic tool in detecting residual and recurrent pediatric cholesteatoma with a pooled sensitivity of 89.4% (95%CI 51.9%–98.5%) and pooled specificity of 92.9% (95%CI 81.4%–97.5%). However, given the small cohort sizes and heterogeneity of studies, there is a wide confidence interval
Conclusions
This systematic review and meta-analysis demonstrates a high specificity but uncertain sensitivity of non-EPI DW-MRI in the detection of residual and recurrent cholesteatoma in children following primary surgery. Further research is warranted to determine the specific role of DW-MRI in the postoperative monitoring of pediatric cholesteatoma patients, namely when and how often children should be referred for imaging and in which cases the method can be used to completely replace second-look
Funding
This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.
Conflicts of interest
The authors disclose no conflicts of interest.
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