Linking MRI postprocessing with magnetic source imaging in MRI-negative epilepsy.
OBJECTIVE
MRI-negative (MRI-) pharmacoresistant focal epilepsy (PFE) patients are most challenging for epilepsy surgical management. This study utilizes a voxel-based MRI postprocessing technique, implemented using a morphometric analysis program (MAP), aiming to facilitate detection of subtle focal cortical dysplasia (FCD) in MRI- patients. Furthermore, the study examines the concordance between MAP-identified regions and localization from magnetic source imaging (MSI).


METHODS
Included in this retrospective study were 25 MRI- surgical patients. MAP was performed on T1-weighted MRI, with comparison to a normal database. The pertinence of MAP+ areas was confirmed by MSI, surgical outcome and pathology. Analyses of MAP and MSI were performed blindly from patients' clinical information and independently from each other.


RESULTS
The detection rate of subtle changes by MAP was 48% (12/25). Once MAP+ areas were resected, patients were more likely to be seizure-free (p=0.02). There were no false positives in the 25 age-matched normal controls. Seven patients had a concordant MSI correlate. Patients in whom a concordant area was identified by both MAP and MSI had a significantly higher chance of achieving a seizure-free outcome following complete resection of this area (p=0.008). In the 9 resected MAP+ areas, pathology revealed FCD type IA in 7 and type IIB in 2.


CONCLUSIONS
MAP shows promise in identifying subtle FCD abnormalities and increasing the diagnostic yield of conventional MRI visual analysis in presurgical evaluation of PFE. Concordant MRI postprocessing and MSI analyses may lead to the noninvasive identification of a structurally and electrically abnormal subtle lesion that can be surgically targeted.
Epilepsy Center, Cleveland Clinic, Cleveland, OH.
Zhong I
ZI
Wang
Andreas V
AV
Alexopoulos
Stephen E
SE
Jones
Imad M
IM
Najm
Aleksandar
A
Ristic
Chong
C
Wong
Richard
R
Prayson
Felix
F
Schneider
Yosuke
Y
Kakisaka
Shuang
S
Wang
William
W
Bingaman
Jorge A
JA
Gonzalez-Martinez
Richard C
RC
Burgess
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015331:Cohort Studies; D004569:Electroencephalography / Q000379:methods; D004827:Epilepsy / Q000175:diagnosis* / Q000503:physiopathology / Q000601:surgery*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D016343:Monitoring, Intraoperative / Q000379:methods*; D012189:Retrospective Studies; D016037:Single-Blind Method; D055815:Young Adult
MEG; MRI; MRI-negative epilepsy; MSI; epilepsy; focal cortical dysplasia; image processing; magnetoencephalography; presurgical evaluation; voxel-based morphometric MRI postprocessing