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Fast spin-echo MR in hippocampal sclerosis: correlation with pathology and surgery
J H Kim1, R D Tien, G J Felsberg
1Department of Radiology, Duke University Medical Center, Durham, NC 27710, USA.
Purpose:
To identify the extent of hippocampal sclerosis in temporal lobe epilepsy with fast spin-echo MR and correlate it with histopathologic findings and surgical outcome.
Methods:
MR images of 30 patients with temporal lobe epilepsy and pathologically proved hippocampal sclerosis and 30 control subjects were obtained using a fast spin-echo technique with 4000/100/4 (repetition time/echo time/excitations), 16 echo train, 2- to 3-mm section thickness with interleave, 256 x 256 matrix, and 18-cm field of view. Criteria for MR diagnosis of hippocampal sclerosis included hippocampal atrophy diagnosed with MR volumetry and/or T2-weighted signal change. Hippocampal sectional areas were plotted, and T2 signal changes were topographically evaluated to identify the extent of hippocampal sclerosis, which was subsequently correlated with histopathologic findings and surgical outcome.
Results:
Hippocampal sclerosis was diffuse, involving both hippocampal head and body, in 96.7% of patients (29 of 30 patients). One patient had normal MR findings. Focal hippocampal sclerosis was not seen. Histopathologic findings of hippocampal sclerosis were present in all 29 patients who had abnormal MR findings. Eighty-six percent of patients (18 of 21 patients), who were followed for at least 1 year after temporal lobectomy, were seizure free (81%, 17 of 21 patients) or significantly improved (5%, 1 of 21 patients).
Conclusion:
Fast spin-echo MR enables accurate definition of the extent of hippocampal sclerosis in patients with temporal lobe epilepsy. All cases of hippocampal sclerosis identified in this study involved the hippocampus diffusely. However, leaving the posterior portion of the hippocampus during surgery does not seem to be a major factor influencing surgical outcome.
Insights
Fast spin-echo MRI accurately defines the extent of hippocampal sclerosis in temporal lobe epilepsy. This imaging technique correlates well with histopathology and surgical outcomes, with most patients achieving seizure freedom post-operatively.
Area of Science:
- Neuroradiology
- Epilepsy diagnostics
- Magnetic Resonance Imaging (MRI)
Background:
- Temporal lobe epilepsy (TLE) is often associated with hippocampal sclerosis.
- Accurate assessment of hippocampal sclerosis extent is crucial for surgical planning.
- Conventional MRI may not always fully delineate the affected areas.
Purpose of the Study:
- To determine the extent of hippocampal sclerosis in TLE using fast spin-echo MRI.
- To correlate MRI findings with histopathologic results.
- To evaluate the relationship between MRI-defined extent and surgical outcomes.
Main Methods:
- Fast spin-echo MRI was performed on 30 TLE patients and 30 controls.
- MR criteria included hippocampal atrophy and T2-weighted signal changes.
- Hippocampal volumetry and T2 signal topography were analyzed and correlated with pathology and surgery.
Main Results:
- Diffuse hippocampal sclerosis was identified in 96.7% of TLE patients.
- MRI findings correlated perfectly with histopathology in abnormal cases.
- 86% of surgically treated patients experienced seizure freedom or significant improvement.
Conclusions:
- Fast spin-echo MRI is effective in defining the extent of hippocampal sclerosis in TLE.
- Hippocampal sclerosis in this cohort was consistently diffuse.
- Posterior hippocampus preservation during surgery did not negatively impact outcomes.