American Journal of Neuroradiology 27:1717-1724, September 2006
© 2006 American Society of Neuroradiology
PEDIATRICS
Diffusion Tensor Imaging in Hydrocephalus: Initial Experience
a The Levie-Edersheim-Gitter Institute for Functional Brain Imaging, Tel Aviv Sourasky Medical Center and Tel Aviv University, Israel
b Department of Neurobiochemistry, Tel Aviv University, Tel Aviv, Tel Aviv, Israel
c Department of Neuroradiology, Tel Aviv-Sourasky Medical Center, Tel Aviv, Israel
d Department of Pediatric Neurosurgery, Dana Children’s Hospital, Tel Aviv Sourasky Medical Center, Tel Aviv, Israel
e Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
f Section on Tissue Biophysics and Biomimetics, Laboratory of Integrative and Medical Biophysics, National Institute of Child Health and Human Development, The National Institutes of Health, Bethesda, Md
Please address correspondence to Yaniv Assaf, MD, Department of Neurobiochemistry, Faculty of Life Sciences, Tel Aviv University, Tel Aviv, 69978, Israel; e-mail: asafyan{at}zahav.net.il
PURPOSE AND BACKGROUND: Diffusion tensor imaging (DTI) is an MR imaging–based technique that provides an in vivo tool for visualization of white matter tracts. In this preliminary study, we used this technique to investigate the diffusion characteristics of white matter tracts in patients with hydrocephalus before and after surgery and compared them with age-matched volunteers.
MATERIALS AND METHODS: Seven patients with different types of acute hydrocephalus (defined by acute clinical signs of increased intracranial pressure and imaging evidence of enlarged ventricles) underwent MR imaging including a DTI protocol before and after surgery for shunt placement/revision or ventriculostomy. Eight age-matched healthy subjects served as a control group. The DTI was acquired in a clinical setting that included 6 gradient directions with a b value of 1000 s/mm2.
RESULTS: Before surgery, in fiber systems lateral to the ventricles (corona radiata), the diffusion parallel to the fibers was increased (+10%) and the diffusion perpendicular to the fibers was decreased (–25%) in all patients, resulting in an overall increase in the fractional diffusion anisotropy (FA, +28%). Following surgery, the FA values approached those of control values in all except 1 patient. In the corpus callosum, the presurgery FA values in patients with hydrocephalus (HCP) were lower than those of control values, and no significant changes were seen following surgery.
CONCLUSIONS: DTI can distinguish the compression characteristics of white matter before and after surgery in patients with HCP. At the acute stage of the disease, DTI characteristics point to white matter compression as a possible cause of the observed changes.