Early and Delayed MR and PET Changes after Selective Temporomesial Radiosurgery in Mesial Temporal Lobe Epilepsy
,
Jean Regis
,a,
Franck Semaha,
R. Nick Bryana,
Olivier Levriera,
Marc Reya,
Yves Samsona and
Jean-Claude Peraguta
a From the Departments of Stereotactic and Functional Neurosurgery (J.R., J.C.P.), Neuroradiology (O.L.), and Neurophysiology (M.R.), La Timone Hospital, Marseille, France; Inserm U 334, Service Hospitalier F. Joliot, CEA, Orsay, France (F.S., Y.S.); the Department of Neurology, La Salpêtrière Hospital, Paris, France (F.S., Y.S.); and the Department of Radiology, National Institutes of Health, Baltimore, MD (R.N.B.).

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FIG 1. 25-year-old man with 19-year history of drug-resistant complex partial seizures who underwent selective temporomesial gamma knife radiosurgery.
A, Axial T1- and T2-weighted MR images and FDG-PET scan 10 months after treatment show mild right temporal mass effect with effacement of the right perimesencephalic cistern. There is slightly decreased T1 signal and heterogeneous T2 signal in the swollen hippocampus (target). More extensive abnormalities are reflected by diffusely increased T2 signal in the temporal lobe white matter and anatomically continuous tracts, such as the internal capsule, but not in the contiguous but anatomically separate, brain stem.
B, Axial pre- and postcontrast T1- and T2-weighted images 31 months after treatment show diffuse atrophy, a shrunken hippocampus with decreased T1 and increased T2 signal, and minimal surrounding contrast enhancement. The FDG-PET scan shows a decrease in the extent of temporal lobe hypometabolism, now restricted to the medial and polar portion of the lobe.
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