Cerebral blood flow in temporal lobe epilepsy: a partial volume correction study

Area of Science:

• Neuroimaging
• Epilepsy Research
• Cerebrovascular Physiology

Background:

• Brain atrophy in temporal lobe epilepsy (TLE) can skew positron emission tomography (PET) measures of brain function.
• Previous studies indicate overestimation of deficits in glucose metabolism (CMR(glu)) and neuroreceptor binding.
• The impact of atrophy on cerebral blood flow (CBF) measurements in TLE remains unclear.

Purpose of the Study:

• To evaluate cerebral blood flow (CBF) deficits in TLE patients before and after partial volume correction (PVC).
• To compare the effects of PVC on CBF versus CMR(glu) in TLE.
• To investigate the relationship between disease duration and functional/perfusion deficits.

Main Methods:

• Quantitative CBF and CMR(glu) measurements were obtained using PET in 21 TLE patients and 9 controls.
• Magnetic resonance imaging-based partial volume correction (PVC) was applied to PET data.
• Asymmetry indices (AIs) for CBF and CMR(glu) were calculated and compared.

Main Results:

• Before PVC, TLE patients showed significantly lower CBF in most regions compared to controls.
• After PVC, significant CBF deficits were confined to fewer regions, including the insula and amygdala.
• CBF asymmetry indices in TLE were smaller than CMR(glu) indices, and disease duration correlated with CMR(glu) AIs, not CBF AIs.

Conclusions:

• Partial volume correction (PVC) is essential for accurate PET-assessed cerebral blood flow (CBF) in TLE.
• Observed reductions in CBF in TLE are primarily attributed to structural brain changes rather than solely metabolic alterations.
• These findings highlight the importance of accounting for atrophy in neuroimaging studies of TLE.