Post-operative MRI detection of residual cholesteatoma in pediatric patients- The yield of serial scans over a long follow-up

Objectives: Non-echo-planar diffusion weighted magnetic resonance imaging (Non-EPI DWI MRI) is commonly used for follow-up after cholesteatoma surgery. MRI has a critical role in the evaluation of residual disease, where physical examination will commonly demonstrate an intact tympanic membrane. The aim of our study was to assess the timing of residual cholesteatoma identification on serial MRI scans and the yield of MRI follow up after canal wall up tympano-mastoidectomy. Methods: A retrospective chart review of children that underwent canal wall up tympano-mastoidectomy due to cholesteatoma in Schneider Children's Medical Center during 2004-2016, and were followed up both clinically and with MRI. Results: Seventy-seven children (89 ears) were included, who altogether underwent 166 surgeries (77 revisions). Average follow-up was 66 +/- 34.4 months. During follow up, 244 scans were performed; 19 cases of residual disease were diagnosed by MRI and confirmed in surgery. The mean time from surgery and an MRI positive for residual disease was 29.7 +/- 16 months (range: 10-66). In 9/19 cases (47%), at least one negative MRI preceded the scan positive for residual disease, and in 4 cases at least two initial scans were negative. Conclusions: MRI plays an important role in the diagnosis of residual disease after cholesteatoma surgery. In our cohort. Almost half of the cases diagnosed with residual disease had at least one negative scan prior to the positive one, emphasizing the importance of close radiological follow-up with serial scans after surgery.