Application of an objective method for localizing bilateral cortical FDG PET abnormalities to guide the resection of epileptic foci.
OBJECTIVE
In order to improve the objective localization of bilateral cortical abnormalities in positron emission tomography (PET) image volumes, we developed a new three-dimensional image processing technique. The accuracy of this approach with respect to invasive subdural electroencephalography (EEG) data was assessed in a group of children with neocortical epilepsy.


METHODS
Glucose PET image volumes were obtained from 12 epileptic children (mean age 5.2 +/- 4.3 years). Bilateral cortical areas of abnormal glucose metabolism were objectively determined using two conditional criteria assessed against a normal database. The normal database was derived from a group of 15 adult controls (mean age 27.6 years). The spatial relationship between seizure onset electrodes and PET abnormalities was assessed using a conventional receiver operating characteristic (ROC) analysis as well as using a newly defined spatial proximity index (SPI), which characterizes the association between adjacent, but not coincident, abnormalities.


RESULTS
ROC analysis at the 2 standard deviation (SD) threshold, revealed an accuracy of 65% to detect seizure onset areas with a sensitivity of 64 +/- 17% and a specificity of 66 +/- 24%. Sensitivity decreased to 46 +/- 24% at the 3-SD threshold with a specificity of 80 +/- 21% (accuracy 75%). The average value for the SPI was determined as 3.82 +/- 1.65 which was 20% lower than the SPI value calculated using a simple in-plane two-dimensional asymmetry between homotopic cortical segments (4.52 +/- 3.82).


CONCLUSIONS
The presented image processing technique improves localization of cortical abnormalities and provides valuable imaging clues for placement of subdural EEG grids prior to surgical resection.
Muzik
Otto
O
Department of Pediatrics and Radiology, Children's Hospital of Michigan, 3901 Beaubien Blvd, Detroit, MI 48201, USA. otto@pet.wayne.edu
Pourabdollah
Siamak
S
Juhasz
Csaba
C
Chugani
Diane C
DC
Janisse
James
J
Draghici
Sorin
S
D000293:Adolescent; D000328:Adult; D000465:Algorithms; D001921:Brain / Q000000981:diagnostic imaging / Q000601:surgery; D002675:Child, Preschool; D004827:Epilepsy / Q000000981:diagnostic imaging* / Q000601:surgery*; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D021621:Imaging, Three-Dimensional / Q000379:methods*; D007223:Infant; D008297:Male; D010363:Pattern Recognition, Automated / Q000379:methods; D049268:Positron-Emission Tomography / Q000379:methods*; D019275:Radiopharmaceuticals; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D025321:Surgery, Computer-Assisted / Q000379:methods*
D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18