Abstracts

Rationale: Hippocampal sclerosis (HS) is the most common cause of refractory temporal lobe epilepsy and is characterised by neuron loss and gliosis. HS can be identified on MRI by signal increase on T2 weighted images and volume loss on T1 weighted volume images. The Periodically Rotated Overlapping Parallel Lines with Enhanced Reconstruction (“PROPELLER”) sequence has excellent tissue contrast and compensates for subjects moving during scans. The aim of the current report was to explore PROPELLER image quality of the hippocampus compared to routine sequences. Methods: Routine sequences (T1-volume, T2-weighted, PD and FLAIR images) and PROPELLER images were acquired in four presurgical patients with HS using a GE 3T Excite HD scanner. Resected tissue was stained with LFB, Timms, and for GFAP, NeuN and dynorphin immunohistochemistry. Hippocampal sections were compared with PROPELLER images.Results: PROPELLER images were T2 weighted and had superior tissue contrast compared to routine sequences. PROPELLER images showed the internal hippocampal structures and tissue changes associated with HS, corresponding with histopathology. Myelinated tissue in stratum moleculare, lacunosum and radiatum displayed low PROPELLER signal whereas gliosis in CA1-4 displayed high signal. There was an abrupt transition from normal tissue (subiculum) to atrophy/gliosis (CA1) on both PROPELLER images and histopathological sections.Conclusions: The PROPELLER sequence provided fast imaging with excellent contrast in patients who did not move overtly, negating the inevitable subtle movements during scans. More detailed in vivo studies of the hippocampal formation, investigating subtle abnormalities such as end folium sclerosis, and the neocortex are now possible and may increase the diagnostic yield of MRI.