PET and ictal SPECT can be helpful for localizing epileptic foci

Abstract

Purpose of reviewFunctional neuroimaging with PET and SPECT is a commonly used tool in presurgical evaluation. The following article reviews the literature of PET and SPECT in presurgical assessment of epilepsies published in the last year.Recent findingsFDG-PET adds concomitant information in temporal and extratemporal lobe epilepsy in adults and children. The pattern of hypometabolism in FDG-PET is a good additional predictor or seizure outcome in TLE with mesial temporal sclerosis or negative MRI. There is growing evidence that diagnostic value of FDG-PET increases with postprocessing. Although several methods were applied in the reviewed literature, all of them seem to outperform the visual analysis. Imaging of the epileptic focus with ictal SPECT is depending on short injection latencies. It is particularly useful in patients with nonlesional MRI and mostly of extratemporal localization. Areas of hyperperfusion remote of SOZ are reflecting the epileptic network. Combining more concordant investigations including PET and SPECT in MRI-negative evaluation adds to better presurgical stratification and therefore, better postsurgical outcome. FET-PET shows increased uptake in status epilepticus.SummaryPET and SPECT are important investigations to localize the epileptic focus in temporal lobe and nonlesional extratemporal epilepsies. Postprocessing for both modalities is important to increase diagnostic value.

Subtraction Ictal SPECT coregistered to MRI (SISCOM) as a guide in localizing childhood epilepsy

“…Therefore, it is used as a complementary rather than alternative technique to SISCOM. [28][29][30][31] In our study, SISCOM could localize the PEZ in 27.8% of the patients with noninformative MRI. In the study by Perissinotti et al, SISCOM was able to localize the PEZ in 57.6% of the patients with noninformative MRI.…”

“…It should be stressed that FDG‐PET does not visualize the seizure onset zone, but the functional deficit zone. Therefore, it is used as a complementary rather than alternative technique to SISCOM …”

Follow-Up of Brain Single-Photon Emission Computed Tomography (SPECT) and Magnetic Resonance Imaging (MRI) in a Case of Seizure Caused by Osmotic Demyelination Syndrome

“…In our case, prominent hyperperfusion in the right cortex was shown on the brain perfusion SPECT, which was done on the day of the seizure ( Figure 1 ). Hyperperfusion in the seizure focus on brain perfusion SPECT on the ictal timing is a well-known feature [ 11 ]. In our case, hyperperfused lesions on brain SPECT were strongly correlated with the lesions shown by MRI changes – T2 hyperintensity with mild diffusion restriction ( Figure 2 ).…”

Application of MRI Post-processing in Presurgical Evaluation of Non-lesional Cingulate Epilepsy

“…demonstrated that rapid spread of epileptic activities could result in widespread hypometabolism, sometimes remote to the EZ. Diffuse regions of hyperperfusion might reflect the epileptic network which includes the epileptic focus as well as the propagation pathways away from the onset, further complicating the task of localization ( 25 ). Although MEG has theoretical advantages including high spatial and temporal resolution in identifying epileptic activities from deep structures compared to scalp EEG ( 26 ), its localization seemed to be limited for CC as shown in our study, perhaps due to the CC producing radially oriented sources difficult to be detected by MEG source localization.…”