Study Of T2 Relaxometry In Evaluation Of Epilepsy In Human

Part I T2 Relaxation Time of Normal Human Brainand it's Change with AgingPurpose: To determine whether the average T2 relaxation time values of brain differ with age, sex and hemisphere, and the effect of aging on T2 relaxation time values, also to establish reference values of the absolute T2 relaxation time for further pathological studies. Material and Methods: Subjects (18 men and 20 women) were chosen from a healthy population; Two age groups were defined as adolescent group(age≤17 years old) and adult group(over 17 years old). All subjects were examined, including routine cranial MRI scan and T2 relaxometry sequence in oblique axial plane which is parallel to the long axis of hippocampus at 3.0 T MR. The data were transferred to the workstation ,analyzed by research T2 mapping software on Functool. Bilateral T2 relaxation time values were determined in 9 regions of interest encompassing the entire brain, including: the amygdala, the hippocampus , the caudate nucleus; the putamen, the thalamus ,frontal, parietal, occipital, temporal white matter. Results: The T2 relaxation time values in different brain regions were as follows: the amygdala 108.32±8.68ms, the hippocampus 114.99±9.16ms, caudate nucleus 98.98±5.67ms, putamen 86.00±7.95ms, the thalamus 86.34±5.47ms, temporal white matter 92.28±5.95ms,occipital white matter 102.95±5.75ms, frontal white matter 96.49±5.62ms; parietal white matter 107.28±6.01ms (P<0.05) . The T2 relaxation time values in gray matter except the putamen and thalamus is higher than that in white matter. No difference was observed between hemispheres, difference between different genders is found. The T2 relaxation time values significantly differ in different age groups in caudate nucleus; the putamen; the thalamus; the amygdala and the hippocampus. The T2 relaxation time values significantly decreased with advancing age in amygdala(r=-0.387, P<0.05), the hippocampus (r=-0.348, P<0.05), caudate nucleus (r=-0.526 P<0.05)and putamen(r=-0.764, P<0.05). Conclusion: Gray matter has a highter T2 relaxation time values than the white matter, the T2 relaxation time values of adult human brain show difference between genders in different regions, but no difference is found between the hemispheres. The T2 relaxation time values significantly decreased with advancing age in the amygdala, the hippocampus, caudate nucleus and putamen ; this change is most obviously in the putamen.Part II T2 Relaxometry in the MRI-negative Epilepsy and its Correlation with Clinical CharacteristicsPurpose: To determine whether the T2 relaxation time values in brain correlate with the clinical characteristic, the onset age and the frequency of seizure. Material and Methods: Subjects including 54 MRI-negative patients; 20 controls from healthy population. Bilateral T2 relaxation time values were determined in 9 regions of interest encompassing the entire brain, including: the amygdala and the hippocampus, the caudate nucleus; the putamen; the thalamus; frontal, parietal, occipital, temporal, white matter;.The clinical characteristics is divided into four groups:the 1^st group,simple partial seizure, the 2^nd group ,complex partial seizure, the 3^rd group ,absence seizures ,the 4^th group generalised tonic-clonic seizure. The patient group is divided into four frequency levels: the 1^st level with frequency more than once a day ;the 2nd level with frequency more than once a week, less than once a day; the 3rd level with frequency more than once a month, less than once a week; the 4^th level with frequency more than once a year, less than once a month. Results: The T2 relaxation time values in amygdala in epilepsy group is higher than the controls (115.92±9.15:110.36±5.4, P=0.001). The T2 relaxation time values in caudate nucleus, the putamen, thalamus ,temporal and occipital white matter in the first epilepsy group were higher than the 3^rd group, with p values as 0.006,0.042,0.020, 0.026,0.044; The T2 relaxation time values in the hippocampus, the caudate nucleus, the putamen, thalamus,temporal white matter were lower than the 4^th group (p value as follows 0.005,0.001,0.003,0.009). The T2 relaxation time values in amygdala, hippocampus, caudate nucleus, thalamus, temporal and occipital white matter in the 2^nd epilepsy group were higher than the 3^rd group(p value as follows 0.007, 0.021, 0.010, 0.000, 0.006). The T2 relaxation time values in amygdala, hippocampus, caudate nucleus, thalamus ,temporal white matter in the 2^nd epilepsy group were higher than the 4^th group(p value as follows 0.001, 0.002, 0.013, 0.001). Difference was found in the different frequency levels, the temporal, occipital, parietal white matter. After excluding the age factors, the onset age in various regions was correlate with the T2 relaxation time, except occipital and parietal regions (amygdala r=-0.419,p=0.000; hippocampus r=-0.320,p=0.001; caudate nucleus r=-0.362 , p=0.000; putamen r=-0.586, p=0.000;r=-0.481, p=0.000; the temporal white matter r=-0.265, p=0.006; the frontal white matter r=-0.212, p=0.028.No statistical significance was found in the correlation of the T2 relaxation time and the interval between the last onset and the examination day. Conclusion: T2 relaxation time in multiple regions in the epilepsy group is higher than the normal control, T2 relaxation time change in amygdala is of statistical significance. T2 relaxation time in the epilepsy group is correlated with the frequency and the duration,and difference is also found in different clinical group.Part III Application of T2 Relaxometry in Secondary Epilepsy withNegative MRIPurpose: To determine compare the T2 relaxation time values in MRI-negative epilepsy patients with induce factor and those without induce factor. Material and Methods: Subjects including: 9 epilepsy patients with induce factor and 54 without any induce factor. The induce factor including injury, HIE, virus encephalitis, and suspected hippocampal sclerosis. The twenty controls came from healthy population. Results: The T2 relaxation time values in various regions in the epilepsy with induce factor were higher than those without induce factor, and controls. The T2 relaxation time values in amygdala and hippocampus in the epilepsy were higher than the controls (amygdala 116.02±8.16 :110.36±5.4ms, and hippocampus 120.30±10.48 :116.42±8.13ms, P value as 0.000, 0.025). The T2 relaxation time values in amygdale(119.07±8.14:110.36±5.4, P=0.001), hippocampus (125.88±8.80:1 16.42±8.13, P=0.001), caudate nucleus, putamen in the epilepsy with induce factor were higher than the normal controls. The amygdala relaxation time in the epilepsy without induce factor was higher than the normal controls (115.92±9.15:110.36±5.4ms, P=0.000). In the injury group the T2 relaxation time in the occipital white matter was higher than others(P value as 0.001, 0.015; 0.005,0.002,0.001), the amygdala and putamen T2 relaxation time in HIE was higher than the controls, the amygdala and caudate nucleus T2 relaxation time in the encephalitis groups were higher than the normal control, T2 relaxation time in caudate nucleus, frontal and parietal white matter were higher than the epilepsy without inducement, the amygdala and putamen T2 relaxation time in suspected hippocamal sclerosis were higher than the epilepsy without induce factor and normal controls. Conclusions: In the epilepsy patients with induce factors the amygdala and hippocampus T2 relaxation higher than epilepsy patients without induce factor and normal controls. T2 relaxation time in different regions is changed with different induce factor. T2 relaxation can show the abnormality which routine image is normal so that we can probe into the epilepsy network in the point of relaxation time.Part IV Application of Diffusion Tensor ImagingCombined with T2 Relaxometry in the EpilepsyPurpose: To explore the diffusion characteristic in the epilepsy, compare whether the diffusion characteristic correlates with T2 relaxation time values in MRI-negative epilepsy. Material and Methods: Twenty-one epilepsy patients including 19 MRI-negtive epilepsy patients, with 15 temporal ,2 frontal epilepsy and another 2 parietal epilepsy; another two epilepsy patients with positive routine MRI,which hints the diagnosis of ectopic gray matter were included. Ten controls came from healthy population. The MD, FA values and T2 relaxation time values in various regions in the epilepsy were evaluated. Results: The T2 relaxation time values in amygdala in the epilepsy were higher than the controls. Increased MD and decreased FA were found in the temporal lobe. There was statistically significant correlation between the amygdale T2 relaxtion time and the FA value in the temporal white matter. Further more, in the MRI positive cases the DTI demostrated the change of related white matter. Conclusions: In the MRI negative epilepsy patients, the increased MD with decreased ADC in the ipislatral temporal regions, there is correlation between the diffusion change and the T2 relaxation time, which demonstrate there maybe occult pathological change in the idiopathic epilepsy.As for the MRI positive epilepsy, DTI gives more information about white matter. Multimodality MRI is helpful in the exploration of the complicated change in the epilepsy brain, and the onset mechanism and network of epilepsy.