Purchase this article with an account.
Anthony Sherbondy, Robert Dougherty, Brian Wandell; Identification of optic radiation in-vivo using diffusion tensor imaging and fiber tractography. Journal of Vision 2008;8(6):958. doi: 10.1167/8.6.958.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Purpose. Measuring the properties of the white matter pathways from retina to cortex in the living human brain will have many uses for understanding visual performance and disabilities. We use diffusion-weighted magnetic resonance imaging (DWI) and a novel fiber tractography method, ConTrack, to identify the optic radiation (OR) in the living human brain. We illustrate the use of this method for an important clinical application: identifying the Meyer's loop portion of the optic radiation prior to temporal lobe resection for intractable epilepsy.
Methods. DWI data was acquired using a single-shot echo-planar sequence and two b-values, b = 0 and b = 800 s/mm2 along 6 diffusion weighted directions, in a 1.5T GE Signa LX scanner. In eight subjects ConTrack was used to identify the most likely pathway between a sub-volume covering the entire lateral geniculate nucleus (LGN) and a sagittal plane lateral and adjacent to V1.
Results. The most anterior position of the OR pathways was located with respect to multiple landmarks (Figure 1). The location of the anterior tip of the OR and other parameters match the range estimated from dissection results (Table 1); these dissections are used as the gold-standard (Ebeling, 1988).
Discussion. The incidence of visual field defects caused by anterior temporal lobectomies is reported to be from 50% to 100% of those postoperatively assessed with kinetic perimetry (Krolak-Salmon, 2000). The high percentage of vision loss in these procedures is attributed to large individual variability in the course of the anterior projections or Meyer's loop. Previous DTI-FT estimates of the OR miss major portions of the Meyer's loop and underestimate the most anterior position of this visual pathway (Yamamoto, 2005; Miller, 2005). The ConTrack DTI-FT algorithm locates the OR at a distribution of positions that match the estimates obtained using dissection method.
This PDF is available to Subscribers Only