Hippocampal Profiling with Localised MR T2 Relaxometry for Hippocampal Sclerosis: Early Detection and Localisation

Hippocampal Profiling with Localised MR T2 Relaxometry for Hippocampal Sclerosis

Abstract

Background: Hippocampal sclerosis (HS) is the most common cause of Drug-resistant Temporal lobe epilepsy, radiologically characterized by atrophy and increased T2/FLAIR signal. Its accurate detection is important to guide surgery which is the best treatment option. Quantitative evaluation using MR volumetry and T2 relaxometry can yield higher sensitivity in early detection and localization of HS than visual analysis alone. We emphasize the role of T2 relaxometry in the evaluation of Hippocampal sclerosis in our study. The aims and objectives are to evaluate the role of T2 relaxometry in detection and localization of HS, to describe the advantages and accuracy of relaxometry over conventional MR imaging. Subjects and Methods: Prospective study of 2 years duration conducted on 30 patients of either sex and all age groups who presented with high electro-clinical suspicion of HS. MR imaging was done with standard epilepsy protocol on a 3T MRI. T2 relaxometry was done to assess T2 relaxation time of hippocampus using multi-echo sequence. Results: In our study, left MTS was found in 60% of the patients, right MTS was found in 33.3 % of the cases, and bilateral MTS was found in 6.7 % of the cases. Out of 30 patients, 90.0% (27 cases) showed positive findings and 10 % (3 cases) showed normal findings on MR visual analysis. Out of 27 cases with positive MR findings, 25 cases (92.59%) showed increased T2 relaxometry values and 2 cases (7.41%) showed normal T2 relaxometry values. All three cases with negative findings on MR visual analysis showed increased T2 relaxometry values. The T2 relaxometry values were raised on side of epileptogenic origin and mean values were 126.16 6.49 ms in right MTS and 124.01 11.71 ms in left MTS cases. Overall, T2 relaxometry exhibited a sensitivity of 90%, specificity of 93.3 percent, positive predictive value (PPV) of 93.1 percent, negative predictive value (NPV) of 90.32 percent, and diagnostic accuracy of 91.6 percent. Conclusion: T2 relaxation times were elevated in 93.3% of hippocampal sclerosis cases showing its high sensitivity in evaluation of HS. The conclusion is Hippocampal evaluation with T2 relaxometry has significant role in early detection and localization of HS.