Synchrotron x ray induced axonal transections in the brain of rats assessed by high-field diffusion tensor imaging tractography

Serduc, Raphaël; Bouchet, Audrey Michele; Pouyatos, Benoît; Renaud, Luc; Bräuer-Krisch, Elke; Le Duc, Géraldine; Laissue, Jean A.; Bartzsch, Stefan; Coquery, Nicolas; van de Looij, Yohan (2014). Synchrotron x ray induced axonal transections in the brain of rats assessed by high-field diffusion tensor imaging tractography. PLoS ONE, 9(2), e88244. Public Library of Science 10.1371/journal.pone.0088244

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Since approximately two thirds of epileptic patients are non-eligible for surgery, local axonal fiber transections might be of particular interest for them. Micrometer to millimeter wide synchrotron-generated X-ray beamlets produced by spatial fractionation of the main beam could generate such fiber disruptions non-invasively. The aim of this work was to optimize irradiation parameters for the induction of fiber transections in the rat brain white matter by exposure to such beamlets. For this purpose, we irradiated cortex and external capsule of normal rats in the antero-posterior direction with a 4 mm×4 mm array of 25 to 1000 µm wide beamlets and entrance doses of 150 Gy to 500 Gy. Axonal fiber responses were assessed with diffusion tensor imaging and fiber tractography; myelin fibers were examined histopathologically. Our study suggests that high radiation doses (500 Gy) are required to interrupt axons and myelin sheaths. However, a radiation dose of 500 Gy delivered by wide minibeams (1000 µm) induced macroscopic brain damage, depicted by a massive loss of matter in fiber tractography maps. With the same radiation dose, the damage induced by thinner microbeams (50 to 100 µm) was limited to their paths. No macroscopic necrosis was observed in the irradiated target while overt transections of myelin were detected histopathologically. Diffusivity values were found to be significantly reduced. A radiation dose ≤ 500 Gy associated with a beamlet size of < 50 µm did not cause visible transections, neither on diffusion maps nor on sections stained for myelin. We conclude that a peak dose of 500 Gy combined with a microbeam width of 100 µm optimally induced axonal transections in the white matter of the brain.

Item Type:

Journal Article (Original Article)

Division/Institute:

04 Faculty of Medicine > Pre-clinic Human Medicine > Institute of Anatomy
04 Faculty of Medicine > Pre-clinic Human Medicine > Institute of Anatomy > Topographical and Clinical Anatomy
04 Faculty of Medicine > Service Sector > Institute of Pathology

UniBE Contributor:

Bouchet, Audrey Michele

Subjects:

500 Science > 570 Life sciences; biology
600 Technology > 610 Medicine & health

ISSN:

1932-6203

Publisher:

Public Library of Science

Language:

English

Submitter:

Audrey Michele Bouchet

Date Deposited:

11 Sep 2014 11:58

Last Modified:

16 Dec 2014 00:23

Publisher DOI:

10.1371/journal.pone.0088244

PubMed ID:

24505446

BORIS DOI:

10.7892/boris.46905

URI:

https://boris.unibe.ch/id/eprint/46905

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