Diffusion Tensor Tractography-based Analysis of the Pyramidal Tract in Patients with Amyotrophic Lateral Sclerosis

To purchase or authenticate to the full-text of this article, please visit this link: http://dx.doi.org/10.1111/j.1552-6569.2007.00153.x Byline: Yoon-Ho Hong (1), Jung-Joon Sung (1), Sung-Min Kim (1), Kyung-Seok Park (1), Kwang-Woo Lee (1), Kee-Hyun Chang (1), In Chan Song (1) Keywords: Amyotrophic lateral sclerosis; diffusion tensor magnetic resonance imaging; diffusion tensor tractography; pyramidal tract Abstract: ABSTRACT BACKGROUND AND PURPOSE We attempted to measure DTI parameters of the brainstem pyramidal tract using two approaches, ie, simple ROI and tract-specific analyses. Results obtained for healthy subjects and ALS patients were compared. METHODS DTI was performed using a single shot SE-EPI with 25 noncollinear diffusion gradient directions (b= 1000 second/mm.sup.2) and with no diffusion gradient on a 3.0-T MR system in 10 ALS patients and in 8 age- and sex-matched normal controls. To delineate the brainstem pyramidal tract, tractography was performed using two ROIs, ie, a seed ROI at the cerebral peduncle (ROI-1) and a target ROI at the lower pons (ROI-2). ROI-1 was subsequently restricted to voxels that contained streamlines in the tract reconstruction, thus creating a sub-ROI. RESULTS Mean fractional anisotropy (FA) and mean diffusivity values were highly reproducible by tract specific analysis, whereas simple ROI analysis yielded larger variabilities between operators. FA values were significantly lower in ALS patients than in normal controls in the tractography-derived sub-ROI (P= .01), but not in the seed or target ROIs. CONCLUSIONS These results suggest, compared with simple ROI analysis, that tract-specific analysis using DTI fiber-tracking is more reliable and sensitive for detecting upper motor neuron pathology in ALS. Author Affiliation: (1)Department of Neurology, Seoul National University Boramae Hospital, Seoul, South Korea (Y-HH); Department of Neurology, Seoul National University, Seoul, South Korea (J-JS, S-MK); Department of Neurology, Seoul National University Bundang Hospital, Seoul, South Korea (K-SP); Seoul National University Hospital, Seoul National University, College of Medicine-Neurology, Seoul, South Korea (K-WL); Seoul National University Hospital, Seoul National University, College of Medicine-Radiology, Seoul, South Korea (K-HC); Department of Radiology, Seoul National University Hospital, Seoul, South Korea (ICS) Article History: Acceptance: Received December 15, 2006, and in revised form January 25, 2007. Accepted for publication March 5, 2007. Article note: Correspondence: Address correspondence to In Chan Song, PhD, Department of Radiology, Seoul National University Hospital, Yongon-Dong 28, Chongno-Gu, Seoul 110-744, South Korea. E-mail: icsong@radcom.snu.ac.kr.