Learning Objectives: It is advisable to combine non-EPI DW MRI findings with ADC mapping and interpretation using all clinical and radiologic information available. After use of fat obliteration techniques extra care in interpretation is required as fat necrosis can be a cause of false positivity. When in doubt one should not be hesitant to repeat scanning.
Introduction: Non-Echo-Planar Diffusion-weighted magnetic resonance imaging (non-EPI DW MRI)is increasingly proposed to replace the standard second look surgery in the follow-up after cholesteatoma surgery because of its high sensitivity and specificity. However, we have encountered several cases of positive MRI results in patients, in whom no recurrent or residual disease was found during subsequent surgery. We like to discuss our lessons learned.
Methods: Retrospective analysis of all false positive cases in our center during non-EPI DW MRI follow-up, after initial cholesteatoma surgery.
Results: Six patients underwent ear surgery, based on positive non-EPI DW MRI findings, during which no cholesteatoma was found. Case history and all available imaging of these cases were re-evaluated and compared to histologic results. The subsequent causes for false positive non-EPI DW MRI's were fat necrosis (after fat obliteration), fibrous connective tissue, foreign body reaction, calcified material and bone dust.
Conclusion: Non-EPI DW MRI is a reliable method for follow-up but can result in both false-negative as well as false-positive results.
