Voxel-based morphometric magnetic resonance imaging (MRI) postprocessing in MRI-negative epilepsies

• Published in: Annals of neurology Vol. 77; no. 6; pp. 1060 - 1075
• Main Authors: Wang, Z. Irene, Jones, Stephen E., Jaisani, Zeenat, Najm, Imad M., Prayson, Richard A., Burgess, Richard C., Krishnan, Balu, Ristic, Aleksandar, Wong, Chong H., Bingaman, William, Gonzalez-Martinez, Jorge A., Alexopoulos, Andreas V.
• Format: Journal Article
• Language: English
• Published: United States Blackwell Publishing Ltd 01.06.2015; Wiley Subscription Services, Inc
• Subjects: Adult; Aged; Epilepsies, Partial - pathology; Epilepsies, Partial - physiopathology; Epilepsies, Partial - surgery; Female; Humans; Image Processing, Computer-Assisted - methods; Magnetic Resonance Imaging - methods; Male; Medical research; Middle Aged; NMR; Nuclear magnetic resonance; Outcome Assessment (Health Care); Retrospective Studies; Sensitivity and Specificity; Surgical outcomes; Young Adult
• ISSN: 0364-5134; 1531-8249
• DOI: 10.1002/ana.24407

Objective In the presurgical workup of magnetic resonance imaging (MRI)‐negative (MRI− or “nonlesional”) pharmacoresistant focal epilepsy (PFE) patients, discovering a previously undetected lesion can drastically change the evaluation and likely improve surgical outcome. Our study utilizes a voxel‐based MRI postprocessing technique, implemented in a morphometric analysis program (MAP), to facilitate detection of subtle abnormalities in a consecutive cohort of MRI− surgical candidates. Methods Included in this retrospective study was a consecutive cohort of 150 MRI− surgical patients. MAP was performed on T1‐weighted MRI, with comparison to a scanner‐specific normal database. Review and analysis of MAP were performed blinded to patients' clinical information. The pertinence of MAP+ areas was confirmed by surgical outcome and pathology. Results MAP showed a 43% positive rate, sensitivity of 0.9, and specificity of 0.67. Overall, patients with the MAP+ region completely resected had the best seizure outcomes, followed by the MAP− patients, and patients who had no/partial resection of the MAP+ region had the worst outcome (p < 0.001). Subgroup analysis revealed that visually identified subtle findings are more likely correct if also MAP+. False‐positive rate in 52 normal controls was 2%. Surgical pathology of the resected MAP+ areas contained mainly non–balloon‐cell focal cortical dysplasia (FCD). Multiple MAP+ regions were present in 7% of patients. Interpretation MAP can be a practical and valuable tool to: (1) guide the search for subtle MRI abnormalities and (2) confirm visually identified questionable abnormalities in patients with PFE due to suspected FCD. A MAP+ region, when concordant with the patient's electroclinical presentation, should provide a legitimate target for surgical exploration. Ann Neurol 2015;77:1060–1075