Application of diffusion tensor tractography in pediatric optic pathway glioma.
OBJECTIVE
Magnetic resonance imaging is commonly used in diagnosis and surveillance for optic pathway glioma (OPG). The authors investigated the role of diffusion tensor (DT) tractography in assessing the location of visual pathway fibers in the presence of tumor.


METHODS
Data in 10 children with OPG were acquired using a 3T MRI generalized autocalibrating parallel acquisitions DT-echo planar imaging sequence (25 isotropic directions with a b value of 1000 seconds/mm(2), slice thickness 3 mm). Fiber tractography was performed, with seed regions placed within the optic chiasm and bilateral nerves on the coronal plane, including the tumor and surrounding normal-appearing tissue. Tracking was performed with a curvature threshold of 30°.


RESULTS
For prechiasmatic lesions, fibers either stopped abruptly at the tumor or traversed abnormally dilated nerve segments. Similar findings were seen with chiasmatic lesions, with an additional arrangement in which fibers diverged around the tumor. For each patient, DT tractography provided additional information about visual fiber arrangement in relation to the tumor that was not evident by using conventional MRI methods. Retrospective reconstruction of visual fibers in 1 patient with new postoperative hemianopia revealed an unexpected superior displacement of the optic tract that might have been helpful information had it been applied to preoperative planning or surgical navigation.


CONCLUSIONS
Optic pathway DT tractography is feasible in patients with OPG and provides new information about the arrangement of visual fibers in relation to tumors that could be incorporated into surgical navigation for tumor biopsy or debulking procedures.
Departments of Neurosurger, Division of Pediatric NeurosurgeryStanford University School of Medicine, Stanford, California 94305-5327, USA. roblober@stanford.edu
Robert M
RM
Lober
Raphael
R
Guzman
Samuel H
SH
Cheshier
Douglas R
DR
Fredrick
Michael S B
MS
Edwards
Kristen W
KW
Yeom
D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D015986:Confounding Factors, Epidemiologic; D003937:Diagnosis, Differential; D056324:Diffusion Tensor Imaging; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D007223:Infant; D008279:Magnetic Resonance Imaging; D008297:Male; D019635:Neurosurgical Procedures / Q000379:methods; D009897:Optic Chiasm / Q000473:pathology / Q000601:surgery; D020339:Optic Nerve Glioma / Q000150:complications / Q000175:diagnosis* / Q000473:pathology / Q000503:physiopathology / Q000601:surgery*; D019574:Optic Nerve Neoplasms / Q000150:complications / Q000175:diagnosis* / Q000473:pathology / Q000503:physiopathology / Q000601:surgery*; D012107:Research Design; D012189:Retrospective Studies; D014786:Vision Disorders / Q000209:etiology; D014792:Visual Acuity; D014795:Visual Pathways / Q000473:pathology; D055815:Young Adult