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Network Analysis of the Default Mode Network Using Functional Connectivity MRI in Temporal Lobe Epilepsy
Published on: August 5, 2014
T2-weighted and T2 relaxometry images in patients with medial temporal lobe epilepsy
Ana Carolina Coan1, Leonardo Bonilha, Paul S Morgan
1Neuroimaging Laboratory, Department of Neurology, State University of Campinas, 13083-970 Campinas, SP, Brazil.
Purpose:
Quantification of increased T2-weighted MRI signal that is associated with hippocampal sclerosis (HS) can be performed through (1) mean of hippocampal signal in single-echo T2 MRI and (2) hippocampal T2 relaxometry. It is not clear whether these two techniques are equivalent. In this study, we compare the hippocampal signal, detected by single-echo T2 quantification and by T2 relaxometry, in patients with medial temporal lobe epilepsy (MTLE).
Methods:
We studied magnetic resonance images from 50 MTLE patients and 15 healthy subjects. We compared the quantification of a T2 signal from single echo images to T2 relaxometry, both obtained from a manually traced region of interest (ROI) in coronal slices involving the whole hippocampus. Repeated measures ANOVA was used to evaluate the differences in the distribution of the Z-scores from single-echo T2 quantification and T2 relaxometry within subjects.
Results:
We observed a significant difference between the measurements obtained from single-echo T2 quantification and T2 relaxometry (P < .001). Measurements from head, body, and tail of the hippocampus were different (P=.04), with a significant interaction between anatomic location and type of measurement used (P= .008). Post hoc paired comparisons revealed that T2 relaxometry yielded greater Z-scores for the body (P= .002) and tail (P < .0001).
Conclusions:
For each subject with MTLE, T2 relaxometry was able to detect a higher signal in the body and tail of the hippocampus compared to single-echo T2. This is a possible indicator that T2 relaxometry is more sensitive in detecting T2 abnormalities within the body and tail of the hippocampus in patients with MTLE.
Insights
T2 relaxometry is more sensitive than single-echo T2 quantification for detecting hippocampal abnormalities in medial temporal lobe epilepsy (MTLE) patients, particularly in the hippocampus body and tail.
Area of Science:
- Neuroimaging
- Epilepsy Research
- Magnetic Resonance Imaging (MRI)
Background:
- Hippocampal sclerosis (HS) is a common cause of medial temporal lobe epilepsy (MTLE).
- Increased T2-weighted MRI signal in the hippocampus is associated with HS.
- Two methods for quantifying this signal are single-echo T2 quantification and T2 relaxometry.
Purpose of the Study:
- To compare the sensitivity of single-echo T2 quantification and T2 relaxometry in detecting hippocampal signal abnormalities in MTLE patients.
- To determine if these two MRI quantification techniques are equivalent for assessing HS in MTLE.
Main Methods:
- Magnetic resonance images from 50 MTLE patients and 15 healthy subjects were analyzed.
- Hippocampal T2 signal was quantified using both single-echo T2 MRI and T2 relaxometry within manually traced regions of interest.
- Repeated measures ANOVA was used to compare Z-scores from both quantification methods.
Main Results:
- A significant difference was observed between single-echo T2 quantification and T2 relaxometry (P < .001).
- T2 relaxometry yielded significantly higher Z-scores in the hippocampus body (P = .002) and tail (P < .0001) compared to single-echo T2.
- Significant interactions between anatomical location and measurement type were found (P = .008).
Conclusions:
- T2 relaxometry is more sensitive than single-echo T2 quantification in detecting T2 signal abnormalities in the hippocampus body and tail of MTLE patients.
- These findings suggest T2 relaxometry may be a more effective tool for diagnosing HS in MTLE.
