PERAN PEMERIKSAAN MRI DTI DAN MT DALAM MENDETEKSI SKLEROSIS HIPOKAMPUS PADA EPILEPSI LOBUS TEMPORALIS MESIAL INTRAKTABEL DENGAN MRI NORMAL

Abstract

Latar belakang : Etiologi Epilepsi Lobus Temporal Mesial (ELTM) intraktabel tersering adalah sklerosis hipokampus. Sekitar 20-30% pasien epilepsi fokal intraktabel menunjukkan MRI standar normal.MRI DTI dan MT, mempunyai kemampuan menunjukkan substrat epileptogenik. Tujuan : Membuktikan pemeriksaan MRI DTI (MD dan FA) serta rasio MT mempunyai kemampuan yang baik dalam mendeteksi sklerosis hipokampus pada ELTM intraktabel dengan MRI normal yang diukur dari derajat neuronal loss, gliosis dan axonal sprouting. Metode : Penelitian menggunakan desain uji diagnostik. Diagnosis ELTM berdasarkan semiology dan EEG ictal, diagnosis sklerosis hipokampus ditentukan dari pemeriksaan MRI standar, dilanjutkan pemeriksaan MRI DTI, dan MT. Pemeriksaan histopatologi sediaan operasi hipokampus dengan pengecatan NeuN, GFAP dan NPY untuk menilai neuronal loss, gliosis dan axonal sprouting. Hasil : Didapatkan 23 subyek ELTM yang dilakukan operasi dan 10 subyek sehat dengan MRI normal. Dari 23 subyek, pemeriksaan histopatologi menunjukkan 11 sklerosis hipokampus, 12 FCD.Sepuluh subyek ELTM dengan MRI normal, 4 dengan sklerosis hipokampus dan 6 dengan FCD. Nilai MD meningkat secara bermakna, nilai FA dan rasio MT dan MT matlab lebih rendah bermakna dibandingkan subyek sehat. FA (0,17) mempunyai nilai diagnostik tertinggi dengan sensitivitas 81,8%, spesifisitas 72,3%, nilai duga positif 64,3%, nilai duga negatif 89,5%, dan kesesuaian lateralisasi dengan EEG 7/10. FA menunjukkan korelasi sedang bermakna dengan derajat neuronal loss, dan gliosis. MD (1,2637x10-3) dan rasio MT (17,85%) mempunyai sensitivitas 81,2%, spesifisitas 68,2%, nilai duga positif 56,2%, nilai duga negatif 88,2%. AUC FA, MD dan rasio MT adalah 0,89; 0,79; 0,74. Kesesuaian MD dan MTR dengan EEG masing-masing 7/10 dan 6/10 pasien.Tidak didapatkan korelasi antara nilai MD, dan rasio MT dengan derajat neuronal loss, gliosis dan axonal sprouting. Kesimpulan: FA (0,17) mempunyai nilai diagnostik terbaik dalam mendeteksi sklerosis hipokampus. FA mempunyai korelasi sedang bermakna dengan derajat neuronal loss, dan gliosis secara bermakna serta kesesuaian dengan EEG 7 dari 10 pasien. Kata kunci: ELTM intraktabel, MRI normal, MRI DTI, fractional anisotropy, mean diffusivity, rasio Magnetization Transfer, sklerosis hipokampus Introduction: Hippocampal sclerosis is the most common pathology found in intractable MTLE. Standardized T2 and FLAIR MR showed normal MR in 20-30% of these cases. The application DTI and MT sequences may show the epileptogenic zone of MTLE Objectives: The main objective of this research is to prove that DTI (MD and FA) quantitative MRI examination as well as MT ratio are reliable in detecting hippocampal sclerosis on intractable MTLE with normal MRI as measured from the degree of neuronal loss, gliosis and axonal sprouting. Method : The research design was diagnostic test. The MTLE diagnosis was based on semiology and ictal EEG, while hippocampal sclerosis was diagnosed using standardized MRI, followed by MRI DTI and MRI MT examinations. Histopathological analysis of hippocampus with NeuN, GFAP and NPY staining were to measure neuronal loss, gliosis and axonal sprouting. Results: Twenty-three MTLE subjects underwent surgery and 10 non MTLE (healthy subjects) were involved. Histopathological analysis of the 23 respondents were as follows: 11 were hippocampal sclerosis, 12 were FCD. Normal MRI was showed in 10 subjects with MTLE, 4 were hippocampal sclerosis and 6 were FCD. MD value significantly increased, whereas the values of FA, MT ratio and matlab MT ratio significantly lower than healthy subjects. FA (0.17) has the highest diagnostic value, showed by 81.8% sensitivity, 72.3% specificity, 64.3% positive predictive value, 89.5% negative predictive value, and lateralization concurring with EEG 7/10. Moreover, FA showed a significant moderate correlation with neuronal loss, and gliosis degrees. MD (1.2637x10- 3) and MTR (17.85%) had 81.2% sensitivity, 68.2% specificity, 56.2% positive predictive value, and 88.2% negative predictive value. AUC of FA, MD and MTR are 0,89; 0,79 and 0,74. The concurrence between MD and MTR, with EEG were 7/10 and 6/10 patients respectively. There was no correlation between MD and MTR values with the degree of neuronal loss, gliosis, and axonal sprouting. Conclusion: FA (0.17) has the best diagnostic value in detecting hippocampal sclerosis. In addition, it shows a moderate correlation with the degrees of neuronal loss, and gliosis, as well as suitability with EEG of 7 out of 10 patients. Keywords: intractable MTLE, normal MRI, MRI DTI, fractional anisotropy, mean diffusivity, magnetization transfer ratio, hippocampal sclerosis.