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PET/MRI and PET/MRI/SISCOM coregistration in the presurgical evaluation of refractory focal epilepsy
S Fernández1, A Donaire2, E Serès3
1Epilepsy Unit, Hospital Clinic de Barcelona, Barcelona, Spain; Neurology Unit, Medical Division, Hospital Plató, Barcelona, Spain.
Abstract:
We aimed to investigate the usefulness of coregistration of positron emission tomography (PET) and magnetic resonance imaging (MRI) findings (PET/MRI) and of coregistration of PET/MRI with subtraction ictal single-photon emission computed tomography (SPECT) coregistered to MRI (SISCOM) (PET/MRI/SISCOM) in localizing the potential epileptogenic zone in patients with drug-resistant epilepsy. We prospectively included 35 consecutive patients with refractory focal epilepsy whose presurgical evaluation included a PET study. Separately acquired PET and structural MRI images were coregistered for each patient. When possible, ictal SPECT and SISCOM were obtained and coregistered with PET/MRI. The potential location of the epileptogenic zone determined by neuroimaging was compared with the seizure onset zone determined by long-term video-EEG monitoring and with invasive EEG studies in patients who were implanted. Structural MRI showed no lesions in 15 patients. In these patients, PET/MRI coregistration showed a hypometabolic area in 12 (80%) patients that was concordant with seizure onset zone on EEG in 9. In 7 patients without MRI lesions, PET/MRI detected a hypometabolism that was undetected on PET alone. SISCOM, obtained in 25 patients, showed an area of hyperperfusion concordant with the seizure onset zone on EEG in 7 (58%) of the 12 of these patients who had normal MRI findings. SISCOM hyperperfusion was less extensive than PET hypometabolism. A total of 19 patients underwent surgery; 11 of these underwent invasive-EEG monitoring and the seizure onset zone was concordant with PET/MRI in all cases. PET/MRI/SISCOM coregistration, performed in 4 of these patients, was concordant in 3 (75%). After epilepsy surgery, 13 (68%) patients are seizure-free after a mean follow-up of 4.5 years. PET/MRI and PET/MRI/SISCOM coregistration are useful for determining the potential epileptogenic zone and thus for planning invasive EEG studies and surgery more precisely, especially in patients without lesions on MRI.
Insights
Coregistering positron emission tomography/magnetic resonance imaging (PET/MRI) and subtraction ictal SPECT-CT (SISCOM) aids in precisely locating the epileptogenic zone in drug-resistant epilepsy patients, improving surgical outcomes.
Area of Science:
- Neuroimaging
- Epilepsy Surgery
- Medical Diagnostics
Background:
- Accurate localization of the epileptogenic zone is crucial for successful epilepsy surgery in drug-resistant cases.
- Conventional neuroimaging may not always identify subtle abnormalities in patients with refractory focal epilepsy.
- Advanced imaging techniques are needed to improve presurgical evaluation and surgical planning.
Purpose of the Study:
- To evaluate the utility of coregistered positron emission tomography/magnetic resonance imaging (PET/MRI) for identifying the epileptogenic zone.
- To assess the added value of combining PET/MRI with subtraction ictal SPECT-CT coregistered to MRI (PET/MRI/SISCOM).
- To compare neuroimaging findings with long-term video-EEG and invasive EEG monitoring in localizing seizure onset.
Main Methods:
- Prospective study of 35 consecutive patients with refractory focal epilepsy undergoing PET imaging.
- Coregistration of separately acquired PET and structural MRI (PET/MRI).
- When feasible, ictal SPECT and SISCOM were obtained and coregistered with PET/MRI (PET/MRI/SISCOM).
Main Results:
- In patients without MRI lesions (n=15), PET/MRI identified hypometabolism concordant with EEG in 12 (80%) patients.
- PET/MRI detected hypometabolism missed by PET alone in 7 patients with normal MRI.
- SISCOM (n=25) showed hyperperfusion concordant with EEG in 7 of 12 patients with normal MRI; PET/MRI was concordant in all 19 surgically treated patients.
Conclusions:
- PET/MRI and PET/MRI/SISCOM coregistration are valuable tools for precisely localizing the epileptogenic zone.
- These advanced imaging methods are particularly beneficial for patients with normal MRI findings.
- Improved localization facilitates more accurate planning of invasive EEG studies and epilepsy surgery, leading to better seizure control.
