NeuroRehabilitation 23 (2008) 171–174 171 IOS Press Cortical reorganization demonstrated by diffusion tensor tractography analyzed using functional MRI activation Bong Soo Han a , Sang Ho Ahn b and Sung Ho Jang b,* a Department of Radiation Science, Yonsei University College of Health Science, Kangwon-do, Republic of Korea b Department of Physical Medicine and Rehabilitation, College of Medicine, Yeungnam University 317-1, Daemyungdong, Namku, Taegu, Republic of Korea Abstract. The diffusion tensor tractography (DTT) allows the corticospinal tract(CST) to be visualized at the subcortical level and functional MRI (fMRI) is capable of precisely identifying activation sites at the cortex. Therefore, it seems that combined DTT/fMRI would allow more accurate evaluation of the state of the CST. We have attempted to demonstrate cortical reorganization in a patient with cortical hemorrhage using DTT analyzed by fMRI activations. Six normal subjects and a 12-year-old female patient with a hemorrhage in the left fronto-parietal cortex were recruited. fMRI was performed at 1.5-T with timed hand grasp- release movements, and DTT was performed using 1.5-T with a Synergy-L Sensitivity Encoding head coil. Three-dimensional reconstructions of the fiber tracts were obtained using the fMRI activation as the seed region of interest and the CST area of the anterior pons as the target region of interest. The tract of the affected hemisphere originated from the lateral area of the injured precentral knob and descended along the known corticospinal tract pathway. It seems that the motor function of the affected hand was reorganized into the lateral area of the injured precentral knob. Therefore, these combined modalities would be helpful in elucidating the state of the CST. Keywords: Diffusion tensor imaging, functional MRI, corticospinal tract, cerebral infarct 1. Introduction The elucidation of the mechanism of motor function recovery has important implications for stroke rehabil- itation. Suggested motor recovery mechanisms after stroke consist of reorganization into areas adjacent to the injured primary motor cortex, the unmasking of the ipsilateral motor pathway from the unaffected mo- tor cortex to the affected hand, the attribution of sec- ondary motor areas, and the recovery of the damaged contralateral corticospinal tract (CST) [1,2,5,15,19]. * Address for correspondence: Dr. Sung Ho Jang, Department of Physical Medicine and Rehabilitation, College of Medicine, Ye- ungnam University 317-1, Daemyungdong, Namku, Taegu, 705-717, Republic of Korea. Tel.: +82 053 620 3269; Fax: +82 53 620 3269; E-mail: strokerehab@hanmail.net, belado@med.yu.ac.kr. The recent development of diffusion tensor tractog- raphy (DTT) allows the architecture and integrity of white matter tracts, and thus the CST, to be visualized at the subcortical level [1,6,12,14]. In contrast, functional MRI (fMRI) is capable of precisely identifying cortical activation sites due to its excellent spatial resolution at the cortex [13]. Therefore, it seems that combined fM- RI/DTT would allow more accurate evaluation of the state of the CST and cortical reorganization. In recent days, reports of DTT studies for the CST analyzed us- ing fMRI activation as the seed region of interest have begun to surface; however, few studies have reported clinical application of this technique [4,16]. In the current study, we describe a patient with cor- tical hemorrhage, whose hand motor function seemed to be reorganized into the lateral area, as demonstrated by the DTT study analyzed using the fMRI activation results. ISSN 1053-8135/08/$17.00  2008 – IOS Press and the authors. All rights reserved