Diffusivity and quantitative T1 profile of human visual white matter tracts after retinal ganglion cell damage

Abstract

In patients with retinal ganglion cell diseases, recent diffusion tensor imaging (DTI) studies have revealed structural abnormalities in visual white matter tracts such as the optic tract, and optic radiation. However, the microstructural origin of these diffusivity changes is unknown as DTI metrics involve multiple biological factors and do not correlate directly with specific microstructural properties. In contrast, recent quantitative T1 (qT1) mapping methods provide tissue property measurements relatively specific to myelin volume fractions in white matter. This study aims to improve our understanding of microstructural changes in visual white matter tracts following retinal ganglion cell damage in Leber's hereditary optic neuropathy (LHON) patients by combining DTI and qT1 measurements. We collected these measurements from seven LHON patients and twenty age-matched control subjects. For all individuals, we identified the optic tract and the optic radiation using probabilistic tractography, and evaluated diffusivity and qT1 profiles along them. Both diffusivity and qT1 measurements in the optic tract differed significantly between LHON patients and controls. In the optic radiation, these changes were observed in diffusivity but were not evident in qT1 measurements. This suggests that myelin loss may not explain trans-synaptic diffusivity changes in the optic radiation as a consequence of retinal ganglion cell disease.

Predicting Neural Response Latency of the Human Early Visual Cortex from MRI-Based Tissue Measurements of the Optic Radiation

“…We note that many parts of MRI data analysis pipeline are common to those used in our previous works (Oishi et al, 2018;Takemura et al, 2019;Minami et al, 2020).…”

“…2017). First, we estimated the approximate location of the LGN by manual inspection of a T1-weighted MRI data and deterministic tractography from the optic chiasm (Ogawa et al, 2014;Takemura et al, 2019). We then placed an 8mm radius sphere that covered the whole LGN endpoints of streamlines from the optic chiasm.…”

“…We then merged the streamlines identified from the two dMRI sessions (Oishi et al, 2018). Further details on the methods used to identify the optic radiation with ConTrack are described in previous papers (Sherbondy et al, 2008b;Levin et al, 2010;Duan et al, 2015;Malania et al, 2017;Takemura et al, 2019).…”

“…We evaluated the tissue properties of white matter tracts (the optic radiation and the corticospinal tract) based on previously reported methods (Levin et al, 2010;Yeatman et al, 2012;Duan et al, 2015;Takemura et al, 2019;Minami et al, 2020). Briefly, we resampled individual streamlines which belong to white matter tracts to 100 equidistant nodes.…”

Comparison of multiple tractography methods for reconstruction of the retinogeniculate visual pathway using diffusion MRI

“…OT (Dasenbrock et al, 2011;Jin et al, 2019;Schmidt et al, 2018;M. Y. Takemura et al, 2017) ON and OT (de Blank et al, 2013) RGVP (Altıntaş et al, 2017;Hofer et al, 2010) DTI (probabilistic) ON (Zolal et al, 2017) OT (Backner et al, 2018;Frezzotti et al, 2016;Glick-Shames et al, 2019;Hoffmann et al, 2012;Levin et al, 2010;Malania et al, 2017;Maleki et al, 2012;Ogawa et al, 2014;Noa Raz et al, 2015;Noa Raz & Levin, 2014;H. Takemura et al, 2019) ON and OT (Wu et al, 2019) RGVP (Ather et al, 2019) CSD (deterministic) OT (Hofstetter et al, 2019) CSD (probabilistic) ON (Attyé et al, 2018;Miller et al, 2019) OC (Puzniak et al, 2019) OT (Haykal et al, 2019;Kammen et al, 2016;Rutland et al, 2019) ON and OT (Allen et al, 2018;Hales et al, 2018) ON and OC GQI (deterministic) ON (Ho et al, 2019) OT (Burton et al, 2018;Jin et al, 2019;Matsuo et al, 2018) RGVP (Panesar et al, 2019;Yoshino et al, 2016) Abbreviations: ON -optic nerve, OC -optic chiasm, OT -optic tract.…”