The Detection of Progressive Cerebral Damage in Patients with Epilepsy: Preliminary Findings of a Longitudinal Quantitative MRI Study.
Abstract number :
1.203
Submission category :
Year :
2001
Submission ID :
270
Source :
www.aesnet.org
Presentation date :
12/1/2001 12:00:00 AM
Published date :
Dec 1, 2001, 06:00 AM
Authors :
R.S.N. Liu, MRCP, Epilepsy Research Group, Institute of Neurology, London, United Kingdom; L. Lemieux, PhD, Epilepsy Research Group, Institute of Neurology, London, United Kingdom; G.S. Bell, MBBS, Epilepsy Research Group, National Society for Epilepsy, B
RATIONALE: Animal models and human cross-sectional studies suggest that repeated seizures may have a detrimental effect on brain structure and function. Longitudinal studies are needed to determine cause and effect. We are currently performing a community-based serial MRI study in which we aim to rescan 154 patients with chronic active epilepsy, 90 patients with newly diagnosed seizures and 80 age-matched controls after an interval of 3.5 years. We hypothesise that recurrent seizures may lead to secondary damage in the hippocampus, cerebellum and neocortex.
METHODS: Subjects were re-scanned on the same 1.5T GE MRI scanner using identical acquisition sequences as at baseline. Scan pairs were visually compared for qualitative change on T1-, T2-weighted and FLAIR images. Each repeat T1-weighted volume scan was coregistered and intensity matched to the segmented baseline scan, to improve reproducibility and sensitivity to change. Hippocampal (HV) and cerebellar volume (CV) measurements were performed on co-registered scan pairs and matched segmented images respectively. The rater was blinded to the chronological order and clinical status of each image pair. Coregistered image pairs for each subject were displayed side-by-side, and completed traces were displayed for visual reference in the left window whilst the active measurements were performed in the right window. This methodology has been shown to detect HV and CBV changes greater than 3.1% and 3.0% respectively 1. Automatic segmentation was used to provide objective baseline values and measures of change in total brain volume (TBV), intracranial volume (ICV), grey matter (GMV) and white matter volume.
RESULTS: To date, we have rescanned 239 subjects (92 patients with chronic active epilepsy, 63 patients with newly diagnosed seizures, and 85 controls). An interim analysis of the first 53 subjects (24 chronic, 9 new and 20 controls) identified 4 individuals with HV losses outside the normal range, and significant reductions in CBV, TBV and GMV in 2, 3 and 1 subject respectively.
CONCLUSIONS: We present a framework for the objective detection of subtle volumetric change not apparent on visual inspection. This methodology has identified significant volume losses in individual patients with epilepsy. Further analysis on completion of data collection will provide valuable insight into the relationship between seizure activity and brain morphology.
1.Lemieux L et al. Magn.Reson.Imag 2000;18:1027-1033
Support: Wellcome Trust and the National Society for Epilepsy