DOES DIFFUSION WEIGHTED IMAGING PROVIDE LATERALIZING INFORMATION IN TEMPORAL LOBE EPILEPSY?
Abstract number :
1.130
Submission category :
Year :
2005
Submission ID :
5182
Source :
www.aesnet.org
Presentation date :
12/3/2005 12:00:00 AM
Published date :
Dec 2, 2005, 06:00 AM
Authors :
1Tim Wehner, 2Eric LaPresto, 1Ping Liu, 1,2William Bingaman, 1Richard Prayson, 1Jean Tkach, 1Paul Ruggieri, and 1Beate Diehl
In a high percentage of patients with intractable temporal lobe epilepsy (TLE), MRI reveals hippocampal atrophy and increased T2 signal consistent with hippocampal sclerosis (HS). However, a subgroup of TLE patients remains non-lesional on standard temporal lobe protocol MRI. We investigated whether diffusion weighted imaging adds lateralizing information in lesional and non-lesional TLE. 22 patients (9 right, 13 left TLE) who had undergone temporal lobectomy and 18 controls were studied. Using in house developed software, we measured hippocampal volumes (HV, values in cm3) on high-resolution T1-weighted scans. The apparent diffusion coefficients (ADCs, values in 10-5mm2s-1) for the entire hippocampus and three arbitrarily defined rectangular areas of interest within the hippocampal head, body and tail were measured from the co-registered ADC map. Pathology was reviewed and correlated with imaging findings. 14 out of 22 patients had hippocampal atrophy on MRI (defined as volume asymmetry greater than two standard deviations compared to asymmetry in the control group). Overall, resected hippocampi (n=22) were significantly smaller compared to contralateral hippocampi as well as ipsilateral hippocampi in controls (Right TLE: right HV 2.60[plusmn]0.44, left HV 3.19[plusmn]0.55, right control HV 3.82[plusmn]0.57; Left TLE: left HV 3.15[plusmn]0.67, right HV 3.67[plusmn]0.49, left control HV3.81[plusmn]0.54).
ADCs were significantly higher in removed hippocampi compared to contralateral hippocampi as well as ipsilateral hippocampi in controls (Right TLE: ADC right 124.18[plusmn]15.29, ADC left 110.07[plusmn]9.2, ADC control 102.11[plusmn]9.42; Left TLE: ADC left 113.75[plusmn]7.07, ADC right 108.04[plusmn]8.06, ADC control 99.77[plusmn]7.68). These differences were also observed within the three areas of interest.
There was a significant negative correlation between hippocampal volume and the hippocampal body ADC in diseased hippocampi (r=-0.504, p[lt]0.02).
ADCs in the hippocampi contralateral to the epileptogenic zone (n=22) were also higher compared to ipsilateral hippocampi in controls (108.87[plusmn]8.39 vs 100.94[plusmn]8.55).
In the subgroup of 8 patients with non-lateralizing conventional MRIs, ADCs of resected hippocampi were not significantly different compared to the contralateral site (110.03[plusmn]6.66 vs 109.29[plusmn]10.46). Pathology in these patients revealed gliosis only without significant neuronal cell loss. ADCs confirm lateralization in patients with hippocampal atrophy on standard temporal lobe protocol MRI. However, they do not provide lateralizing information in patients with non-lesional conventional MRIs.