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Published on: July 19, 2019
Is the type and extent of hippocampal sclerosis measurable on high-resolution MRI?
H Urbach1, H J Huppertz, R Schwarzwald
1Dept. of Neuroradiology, Medical Center University of Freiburg, Breisacher Str. 64, 79106, Freiburg, Germany, horst.urbach@uniklinik-freiburg.de.
Introduction:
The purpose of this study is to relate hippocampal volume and FLAIR signal intensity to Wyler grading of hippocampal sclerosis (HS).
Methods:
Of 100 consecutive patients with temporal lobe epilepsy and HS as histopathological diagnosis, 32 had high-resolution 3 Tesla MRI and anatomically well-preserved hippocampi following amygdalo-hippocampectomy. Hippocampal volume on 3D T1-weighted gradient echo and signal intensity on coronal FLAIR sequences were determined using FreeSurfer and SPM tools and related to Wyler grading. Seizure outcome was determined after 1 year.
Results:
Histopathology showed four Wyler II, 19 Wyler III, and 9 Wyler IV HS. Hippocampal volumes were 3.08 ml for Wyler II (Wyler II/contralateral side: p > 0.05), 2.19 ml for Wyler III (p < 0.01), 2.62 ml for Wyler IV (p = 0.01), and 3.08 ml for the contralateral side. Normalized FLAIR signals were 1,354 (p = 0.0004), 1,408 (p < 0.0001), 1,371 (p < 0.04), and 1,296, respectively. Wyler II hippocampi were visually normal. Two of four (50%) Wyler II, 16/19 (84%) Wyler III, and 6/9 (66%) Wyler IV patients achieved Engel I outcome.
Conclusions:
Combined volumetry and quantitative FLAIR signal analysis clearly identifies Wyler III and IV HS. Quantitative FLAIR signal analysis may be helpful to identify Wyler II HS.
Insights
Magnetic Resonance Imaging (MRI) techniques, including hippocampal volume and FLAIR signal intensity, can help grade hippocampal sclerosis (HS) severity. Quantitative FLAIR analysis shows promise for identifying even subtle Wyler II HS.
Area of Science:
- Neuroimaging
- Epilepsy Research
- Quantitative MRI
Background:
- Hippocampal sclerosis (HS) is a common cause of temporal lobe epilepsy.
- Accurate grading of HS severity is crucial for treatment planning and prognosis.
- Current grading relies on histopathology, necessitating invasive procedures.
Purpose of the Study:
- To correlate hippocampal volume and FLAIR signal intensity with Wyler grading of HS.
- To evaluate the utility of non-invasive MRI measures in assessing HS severity.
Main Methods:
- Utilized high-resolution 3 Tesla MRI on 32 epilepsy patients with histopathologically confirmed HS.
- Measured hippocampal volume (3D T1-weighted) and FLAIR signal intensity using FreeSurfer and SPM.
- Correlated quantitative MRI metrics with Wyler grades (II, III, IV) and seizure outcomes.
Main Results:
- Significantly reduced hippocampal volumes were observed in Wyler III and IV HS compared to controls.
- Quantitative FLAIR signal intensity was significantly elevated in Wyler II, III, and IV HS.
- Higher Wyler grades correlated with poorer seizure outcomes, though Wyler II hippocampi appeared visually normal.
Conclusions:
- Combined hippocampal volumetry and quantitative FLAIR analysis effectively differentiate Wyler III and IV HS.
- Quantitative FLAIR signal intensity may serve as a valuable tool for identifying Wyler II HS, which is often visually unremarkable on MRI.
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