MRI interpretation errors in adult patients with Medically Refractory Epilepsy

Background/Purpose: Determine the most common MRI interpretation errors in patients with MRE according to our experience in a tertiary academic center with a large volume epilepsy program, in order to raise awareness of the ‘blind spots’ in imaging patients with MRE and to highlight the importance of combining clinical and electroencephalographic information to obtain the most accurate diagnosis.

Materials and Methods: This is a retrospective observational study. All MRE-patients who underwent MRI brain (on 3 Tesla, with dedicated epilepsy protocol), and who were discussed at the weekly interdisciplinary epilepsy conference in our center between January 2008 and July 2023 were included. The initial MRI interpretation and final MRI interpretation results were reviewed.

Results: 886 patients with MRE were included. 300 patients were MRI-negative (33.86%), diagnoses were missed in 95 patients (10.7%), a second diagnosis was missed in patients with dual pathologies in 42 patients (4.74%), findings were misinterpreted in 4 patients (0.45%), an overcall was made in 2 patients (0.2%), and in 5 patients the correct diagnosis was discussed but erroneously deemed absent on initial interpretation (0.56%), resulting in a total of 148 discrepant MRI reports.

MTS comprised the most common pathology encountered overall, followed by encephalomalacia related to prior insult, enlarged amygdala, malformations of cortical development, cavernoma and ulegyria.

The relative proportion of missed focal cortical dysplasia, encephalocele and enlarged amygdala accounted for the commonest misses/misdiagnoses.

Conclusion: Evaluation of patients with MRE requires excellent inter-disciplinary care. Input from all members of the interdisciplinary team is essential for accurate interpretation of MRI in MRE patients for the neuroradiologist.

We hope to inform radiologists of commonly overlooked pathologies in MRI brain interpretation for patients with epilepsy. In doing so, we want to maximize the yield of initial MRI interpretation in these patients.

ABBREVIATIONS: EA, enlarged amygdala; EEG, electroencephalogram; EMR, electronic medical record, FCD, focal cortical dysplasia; MCD, Malformations of Cortical Development; MEG, Magnetoencephalography; MRE, medically refractory epilepsy; MTS, mesial temporal sclerosis; TLE, temporal lobe epilepsy; Positron emission tomrgrpahy (PET), Subtraction Ictal SPECT Co-registered to MRI (SISCOM) SCNH, subcortical nodular heterotopia.