Vasanthakumar Venugopal MD, Presenter: Nothing to Disclose

Ekram Ullah MD, Abstract Co-Author: Nothing to Disclose

Ibne Ahmad MD, Abstract Co-Author: Nothing to Disclose

Sandeep Kumar MD, Abstract Co-Author: Nothing to Disclose

Alex Daniel Prabhu MD, Abstract Co-Author: Nothing to Disclose

Proton magnetic spectroscopy (MRS) and Hippocampal T2 relaxation time (HT2) measurements have been extensively used in the evaluation of hippocampal sclerosis in recent times. However comparative studies between these modalities have rarely been documented. The purpose of our study was to compare the lateralizing ability of these two modalities in hippocampal sclerosis.

The study was done in 23 patients with intractable epilepsy, who were diagnosed as having unilateral hippocampal sclerosis. All these patients were screened for metabolic abnormalities bilaterally using single voxel proton spectroscopy. Lateralization was done using metabolite ratios of NAA/Cho and NAA/Cr calculated from the relative peak height measurements. An NAA/Cho ratio of 0.8 or less and an NAA/Cr ratio of 1.0 or less were regarded as abnormal. T2 relaxometry study was done by acquiring images on a 1.5 T MR scan using a dual echo sequence with contiguous oblique coronal slices. Fitting a single exponential decay equation to the imaging data generated T2 maps. Averages of six slices containing the head, body, and tail of the hippocampus were used to calculate hippocampal T2 relaxation times (HT2). The MRS results were compared with those of MR imaging and HT2 to compare the ability to lateralize the epileptogenic focus.

The concordance rate of MRS and HT2 with conventional MR was 82% and 87% respectively in lateralization of the ipsilateral lesion side. False-lateralization rates for MRS and HT2 were 4 % each. Bilateral positivity on MRS was observed in 22% cases. The concordance rate of MRS and PET was 78%, when comparing the results of the ipsilateral lesion side.

Thus HT2 was found to be more sensitive than MRS in lateralization of seizure focus in hippocampal sclerosis. Possibility of quantitative estimation of abnormality and higher percentage of bilateral positivity on MRS also leaves us with a conclusion that HT2 has a better lateralization potential.

HT2 was found to be more sensitive than MRS in lateralization of seizure focus in hippocampal sclerosis

Venugopal, V, Ullah, E, Ahmad, I, Kumar, S, Prabhu, A, Hippocampal T2 Relaxometry vs 1H MR Spectroscopy: Comparison of Lateralising Ability in Temporal Lobe Sclerosis.  Radiological Society of North America 2010 Scientific Assembly and Annual Meeting, November 28 - December 3, 2010 ,Chicago IL. http://archive.rsna.org/2010/9016157.html