T2 hyperintense signal in patients with temporal lobe epilepsy with MRI signs of hippocampal sclerosis and in patients with temporal lobe epilepsy with normal MRI.
BACKGROUND
Increased MRI T2 signal is commonly present not only in the hippocampus but also in other temporal structures of patients with temporal lobe epilepsy (TLE), and it is associated with histological abnormalities related to the epileptogenic lesion.


OBJECTIVE
This study aimed to verify the distribution of T2 increased signal in temporal lobe structures and its correlations with clinical characteristics of TLE patients with (TLE-HS) or without (TLE-NL) MRI signs of hippocampal sclerosis.


METHODS
We selected 203 consecutive patients: 124 with TLE-HS and 79 with TLE-NL. Healthy controls (N=59) were used as a comparison group/comparative group. T2 multiecho images obtained via a 3-T MRI were evaluated with in-house software. T2 signal decays were computed from five original echoes in regions of interest in the hippocampus, amygdala, and white matter of the anterior temporal lobe. Values higher than 2 standard deviations from the mean of controls were considered as abnormal.


RESULTS
T2 signal increase was observed in the hippocampus in 78% of patients with TLE-HS and in 17% of patients with TLE-NL; in the amygdala in 13% of patients with TLE-HS and in 14% of patients with TLE-NL; and in the temporal lobe white matter in 22% of patients with TLE-HS and in 8% of patients with TLE-NL. Group analysis demonstrated a significant difference in the distribution of the T2 relaxation times of the hippocampus (ANOVA, p<0.0001), amygdala (p=0.003), and temporal lobe white matter (p<0.0001) ipsilateral to the epileptogenic zone for patients with TLE-HS compared with controls but only for the amygdala (p=0.029) and temporal lobe white matter (ANOVA, p=0.025) for patients with TLE-NL compared with controls. The average signal from the hippocampus ipsilateral to the epileptogenic zone was significantly higher in patients with no family history of epilepsy (two-sample T-test, p=0.005).


CONCLUSIONS
Increased T2 signal occurs in different temporal structures of patients with TLE-HS and in patients with TLE-NL. The hippocampal hyperintense signal is more pronounced in patients without family history of epilepsy and is influenced by earlier seizure onset. These changes in T2 signal may be associated with structural abnormalities related to the epileptogenic zone or to the nature of the initial precipitating injury in patients with TLE.
Neuroimaging Laboratory, Department of Neurology, University of Campinas, Campinas, SP, Brazil. Electronic address: kubota187@gmail.com.
Bruno Yukio
BY
Kubota
Neuroimaging Laboratory, Department of Neurology, University of Campinas, Campinas, SP, Brazil. Electronic address: accoan@gmail.com.
Ana Carolina
AC
Coan
Neuroimaging Laboratory, Department of Neurology, University of Campinas, Campinas, SP, Brazil. Electronic address: yasuda.clarissa@gmail.com.
Clarissa Lin
CL
Yasuda
Neuroimaging Laboratory, Department of Neurology, University of Campinas, Campinas, SP, Brazil. Electronic address: fcendes@unicamp.br.
Fernando
F
Cendes
D000293:Adolescent; D000328:Adult; D000368:Aged; D004833:Epilepsy, Temporal Lobe / Q000473:pathology*; D005260:Female; D006624:Hippocampus / Q000473:pathology*; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods* / Q000592:standards; D008297:Male; D008875:Middle Aged; D012598:Sclerosis / Q000473:pathology; D012680:Sensitivity and Specificity; D013702:Temporal Lobe / Q000473:pathology; D066127:White Matter / Q000473:pathology*; D055815:Young Adult
Hippocampal sclerosis; MRI-negative epilepsy; Magnetic resonance; T2 relaxometry; Temporal lobe epilepsy