gms | German Medical Science

57th Annual Meeting of the German Society of Neurosurgery
Joint Meeting with the Japanese Neurosurgical Society

German Society of Neurosurgery (DGNC)

11 - 14 May, Essen

Diffusion tensor imaging in acquired blind humans

Diffusions-Tensor-Bildgebung bei erworbener Blindheit

Meeting Abstract

  • corresponding author U. Bürgel - Department of Neurosurgery, RWTH Aachen University, Aachen
  • F. Schoth - Department of Neuroradiology, RWTH Aachen University, Aachen
  • A. Boström - Department of Neurosurgery, RWTH Aachen University, Aachen
  • P. Reinacher - Department of Neurosurgery, RWTH Aachen University, Aachen
  • T. Krings - Department of Neuroradiology, RWTH Aachen University, Aachen
  • F. Hans - Department of Neurosurgery, RWTH Aachen University, Aachen

Deutsche Gesellschaft für Neurochirurgie. Japanische Gesellschaft für Neurochirurgie. 57. Jahrestagung der Deutschen Gesellschaft für Neurochirurgie e.V. (DGNC), Joint Meeting mit der Japanischen Gesellschaft für Neurochirurgie. Essen, 11.-14.05.2006. Düsseldorf, Köln: German Medical Science; 2006. DocP 04.52

The electronic version of this article is the complete one and can be found online at:

Published: May 8, 2006

© 2006 Bürgel et al.
This is an Open Access article distributed under the terms of the Creative Commons Attribution License ( You are free: to Share – to copy, distribute and transmit the work, provided the original author and source are credited.



Objective: Retinal implants as a future therapy of blindness rely on intact neural transmissions from the retina to the primary visual cortex. Therefore, the microstructural organization of the optic radiation has to be intact. Till now, we do not know if the lack of afferent input in acquired blindness affects the structure of the visual fiber pathways, e.g., resulting in an atrophy of the axons. A structural degeneration of the axons would result in a reduced relative anisotropy. Diffusion tensor MRI (DTI) is sensitive to changes in anisotropy and can, therefore, be used to quantify the relative anisotropy within a fibre tract.

Methods: After giving their written consent, 12 healthy control subjects and 6 acquired blind patients (5x retinitis pigmentosa, 1x meningitis) were investigated at a 1.5 T clinical MR scanner (Philips Intera, Best, The Netherlands) using a standard head coil. For anatomical reference we obtained a high resolution T1-weighted 3-D fast-field gradient echo (FFE) sequence covering the entire head. Corresponding pulse-triggered diffusion weighted multishot spin-echo EPI sequences with two b values (0, 1000 s/mm2) along each of nine different gradient axes were acquired (imaging parameters: TR=1 beat, TE=22msec, FA=90°, FOV=200x200mm, matrix=128x128, slice thickness =2mm, no interslice gap). The DTI images were reoriented to the magnet coordinate system. After computation of the ADC map the eigenvectors and eigenvalues of the tensor were computed in a least squares approach and the tensor with minimal squared errors was chosen. The data were standardized to the MNI (Montreal Neurological Institute) coordinate system using SPM2 (Wellcome Department, London, UK). The relative anisotropy was calculated for every voxel and in order to rule out effects of ageing, the quotient of the anisotropy in the optic radiation and in the pyramidal tract was used. Statistical analysis was performed by applying a single sided two-sampled t-test.

Results: There are no statistically significant differences between the amount of anisotropy in the blind patients versus the control group and in the optic radiation versus the pyramidal tract.

Conclusions: In patients with late onset acquired blindness there is no DTI-detectable evidence for axonal degeneration of the optic radiation. With the optic fibres remaining intact, transmitting electric signals from retinal implants to the visual cortices of the human brain seems to be possible even after decades of acquired blindness.