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Lesion Explorer: A Video-guided, Standardized Protocol for Accurate and Reliable MRI-derived Volumetrics in Alzheimer's Disease and Normal Elderly
Published on: April 14, 2014
Automated 3D MRI volumetry reveals regional atrophy differences in Rasmussen encephalitis
Jan Wagner1, Jan-Christoph Schoene-Bake, Christian G Bien
1Department of Epileptology, University of Bonn, Bonn, Germany. jan.wagner@ukb.uni-bonn.de
Purpose:
Rasmussen encephalitis is a chronic immune-mediated disease leading to unilateral atrophy on magnetic resonance imaging (MRI) and progressive neurologic deficits. Until now, quantitative parameters describing the course of the disease on MRI require manual intervention and are, therefore, time-consuming and observer-dependent. Furthermore, regional atrophy differences cannot be evaluated with the previously published methods. In this study we present a fully automated volumetric approach applied to serial MRI scans of 12 patients with Rasmussen encephalitis.
Methods:
We retrospectively analyzed 12 patients with Rasmussen encephalitis with a disease onset between 2001 and 2008. All patients underwent a total of 66 serial MRI scans including a three-dimensional T(1) data set. The volumetric analysis was based on standard procedures of the freely available software FMRIB Software Library (FSL) and required about 45 min per scan. Furthermore, planimetric analyses were performed on 51 scans as described previously.
Key Findings:
The relative and absolute volume loss of the affected hemisphere was significantly higher compared to the unaffected hemisphere. Referring to regional atrophy differences our results show that the frontal lobe and the insula were preferentially involved in the atrophic process. The degree of hemispheric, parietal, and occipital atrophy was negatively correlated with the age at disease onset, indicating a more aggressive and outspread disease in young children compared to adolescents. Volumetric hemispheric ratio and planimetric hemispheric ratio correlated significantly, but planimetric hemispheric ratio underestimated the real degree of hemiatrophy, especially in patients with predominant affections outside the frontoinsular region.
Significance:
The volumetric analysis presented here offers a precise assessment of the disease progression in Rasmussen encephalitis in an observer-independent and time-efficient manner and gives an interesting insight into the course of the disease on MRI. The degree of atrophy evaluated with this method correlates with clinical parameters and is comparable to atrophy rates in patients receiving immunotherapy in preceding planimetric MRI studies.
Insights
A new automated MRI analysis accurately measures brain atrophy in Rasmussen encephalitis. This method is faster, observer-independent, and reveals disease progression patterns, aiding clinical assessment.
Area of Science:
- Neurology
- Radiology
- Medical Imaging
Background:
- Rasmussen encephalitis is a chronic, immune-mediated neurological disorder.
- It causes progressive unilateral brain atrophy and neurological deficits.
- Current MRI analysis methods are time-consuming and subjective.
Purpose of the Study:
- To present a fully automated volumetric MRI analysis for Rasmussen encephalitis.
- To enable observer-independent and time-efficient assessment of disease progression.
- To evaluate regional atrophy differences and their correlation with disease onset.
Main Methods:
- Retrospective analysis of 66 serial MRI scans from 12 Rasmussen encephalitis patients.
- Application of automated volumetric analysis using FMRIB Software Library (FSL).
- Comparison with previously used planimetric analysis methods.
Main Results:
- Significantly greater volume loss in the affected hemisphere.
- Preferential atrophy in the frontal lobe and insula.
- Earlier disease onset correlated with more aggressive and widespread atrophy.
Conclusions:
- Automated volumetric MRI analysis provides precise, efficient, and observer-independent assessment of Rasmussen encephalitis.
- The method offers insights into disease progression and correlates with clinical parameters.
- This approach is comparable to existing methods but offers significant advantages.
