Patricia Dreessen de Gervai1, Uta N Sboto-Frankenstein2, R Bruce Bolster3, Sunny Thind1, Marco L H Gruwel4, Stephen D Smith3, Boguslaw Tomanek5. 1. National Research Council Institute for Biodiagnostics, Magnetic Resonance Technology, 435 Ellice Avenue, Winnipeg, MB R3B 1Y6, Canada. 2. Alberta Innovates Technology Futures, 435 Ellice Avenue, Winnipeg, MB R3B 1Y6, Canada. Electronic address: UtaFrankenstein@sboto.com. 3. National Research Council Institute for Biodiagnostics, Magnetic Resonance Technology, 435 Ellice Avenue, Winnipeg, MB R3B 1Y6, Canada; Biopsychology Program, Department of Psychology, University of Winnipeg, 515 Portage Avenue, Winnipeg, MB R3B 2E9, Canada. 4. National Research Council Aquatic and Crop Resource Development, 435 Ellice Avenue, Winnipeg, MB R3B 1Y6, Canada. 5. Alberta Innovates Technology Futures, 435 Ellice Avenue, Winnipeg, MB R3B 1Y6, Canada; Multimodal and Functional Imaging Group, Central Europe Institute of Technology, Kamenice 753, Brno CZ-62500, Czech Republic.
Abstract
PURPOSE: The purpose of the current study was to use diffusion tensor imaging (DTI) to conduct tractography of the optic radiations (OR) and its component bundles and to assess both the degree of hemispheric asymmetry and the inter-subject variability of Meyer's Loop (ML). We hypothesized that there are significant left versus right differences in the anterior extent of ML to the temporal pole (TP) in healthy subjects. MATERIALS AND METHODS: DTI data were acquired on a 3T Siemens MRI system using a single-shot Spin Echo EPI sequence. The dorsal, central and ML bundles of the OR were tracked and visualized in forty hemispheres of twenty healthy volunteers. The uncinate fasciculus (UF) was also tracked in these subjects so that it could be used as a distinct anatomical reference. Measurements were derived for the distance between ML-TP, ML and the temporal horn (ML-TH) and ML and the uncinate fasciculus (ML-UF). Paired difference t-tests were carried out with SPSS 14.0. RESULTS: ML and the UF were successfully tracked and visualized in all 20 volunteers. Significant hemispheric asymmetries were found for all measurements with left distances shorter than the right (P<0.005). In 50% of the subjects the left ML-UF distance was ≤1.9 mm. CONCLUSION: The results support our hypothesis and demonstrate that left ML-TP distances are significantly shorter than right ML-TP distances. These asymmetries are also reflected in shorter left distances between ML-TH and ML-UF. Moreover, these results are of interest to left-sided temporal lobe epilepsy surgery because it is not only more likely to disturb the anterior extent of ML but also renders the often closely located posterior aspect of the left UF more vulnerable to potential surgical impact. Crown
PURPOSE: The purpose of the current study was to use diffusion tensor imaging (DTI) to conduct tractography of the optic radiations (OR) and its component bundles and to assess both the degree of hemispheric asymmetry and the inter-subject variability of Meyer's Loop (ML). We hypothesized that there are significant left versus right differences in the anterior extent of ML to the temporal pole (TP) in healthy subjects. MATERIALS AND METHODS: DTI data were acquired on a 3T Siemens MRI system using a single-shot Spin Echo EPI sequence. The dorsal, central and ML bundles of the OR were tracked and visualized in forty hemispheres of twenty healthy volunteers. The uncinate fasciculus (UF) was also tracked in these subjects so that it could be used as a distinct anatomical reference. Measurements were derived for the distance between ML-TP, ML and the temporal horn (ML-TH) and ML and the uncinate fasciculus (ML-UF). Paired difference t-tests were carried out with SPSS 14.0. RESULTS: ML and the UF were successfully tracked and visualized in all 20 volunteers. Significant hemispheric asymmetries were found for all measurements with left distances shorter than the right (P<0.005). In 50% of the subjects the left ML-UF distance was ≤1.9 mm. CONCLUSION: The results support our hypothesis and demonstrate that left ML-TP distances are significantly shorter than right ML-TP distances. These asymmetries are also reflected in shorter left distances between ML-TH and ML-UF. Moreover, these results are of interest to left-sided temporal lobe epilepsy surgery because it is not only more likely to disturb the anterior extent of ML but also renders the often closely located posterior aspect of the left UF more vulnerable to potential surgical impact. Crown
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Authors: Luís M Lacerda; Jonathan D Clayden; Sian E Handley; Gavin P Winston; Enrico Kaden; Martin Tisdall; J Helen Cross; Alki Liasis; Chris A Clark Journal: Front Neurosci Date: 2020-04-08 Impact factor: 4.677
Authors: Lee B Reid; Eloy Martínez-Heras; Jose V Manjón; Rosalind L Jeffree; Hamish Alexander; Julie Trinder; Elisabeth Solana; Sara Llufriu; Stephen Rose; Marita Prior; Jurgen Fripp Journal: Hum Brain Mapp Date: 2021-09-21 Impact factor: 5.038