This study aimed to investigate the potential contribution of morphometric MRI analysis in comparison to other modalities, such as MEG, SPECT and PET, in identifying the epileptogenic focus in patients with cryptogenic epilepsy.
Patients and methods
Study inclusion was limited to epilepsy patients with a monolobar focus hypothesis, as concluded from EEG/seizure semiology and the best individual concordance rate. Feature maps, generated by the MATLAB® “morphometric analysis program” (MAP), were evaluated by a neuroradiologist blinded to conventional MRI and the focus hypothesis (MAP1). In addition, the feature maps were also interpreted by simultaneous matching conventional MRI but, again, with the reader having no knowledge of the focus hypothesis (MAP2).
In 12 out of 51 patients, true-positive findings were achieved (MAP1: sensitivity 24%; specificity 96%). The sensitivity of the MAP1 results was superior extratemporally. After matching conventional MRI, FCD was traced in six of the 12 patients (MAP2: sensitivity 12%; specificity 100%). MEG sensitivity was 62%. Sensitivity of interictal and ictal SPECT was 20% and 50%, respectively. PET was not as sensitive extratemporally (19%) as temporally (82%). The greatest correspondence with the best individual concordance rate was noted with PET (14/16; 88%) and MEG (8/10; 80%), followed by interictal (5/8; 63%) and ictal (9/15; 60%) SPECT. Results for MAP1 were 53% (10/19), and 100% for MAP2 (6/6).
Although MAP sensitivity and specificity results are lower in comparison to other modalities, implementation of the technique should be considered first, before arranging any further investigations. The present study results offer guidelines for the implementation, interpretation and concordance of diagnostic procedures.Le texte complet de cet article est disponible en PDF.
Keywords : Epilepsy, Cryptogenic, MRI, Morphometric analysis, MAP, VBM, MEG, SPECT, PET