Study : Functional Imaging Correlates of Functional Recovery in Children who have Undergone Complete Hemispherectomy
Children who have experienced even extensive unilateral brain injury often show impressive functional recovery, which is presumed to reflect neural reorganization. For instance, children who have undergone cortical hemispherectomy, often show only mild and specific neurocognitive deficit (Devlin et al., 2003). There have been relatively few studies of neural correlates of recovery however, and most of the studies that have been done have included small sample sizes (i.e., case studies). The proposed study aims to determine structural and functional imaging correlates of functional recovery in children who have undergone complete hemispherectomy.
MR image acquisition. MRI scans will be performed using a 3T Signa EXCITE scanner (GE Healthcare, Waukesha, WI) with an 8-channel ASSET head coil. To obtain high-resolution anatomical image volume, we will perform a three-dimensional T1 weighted sequence spoiled gradient echo sequence (SPGR) sequence with echo time TE = 3.66 ms, repetition time TR = 9.12 ms, TI= 400 ms, three averages, and flip angle of 13 degrees. The data will be reconstructed into 120 coronal slices (matrix size 256 x 256, pixel size = 0.94 mm) with 1.2 mm slice thickness and no gap. The total scanning time for this 3D acquisition will be approximately 3 minutes.
Diffusion tensor images will be acquired in axial planes with diffusion sensitization gradients applied in 55 non-collinear directions and a b-value of 1000 [s/mm2]. The same imaging parameters will be used to acquire one T2-weighted image volume (b~0 [s/mm2]). All image volumes will be acquired at TE = 88.7ms, TR = 1250 ms, and number of average = 1. A set of 45 axial slices of 3 mm thickness will be acquired without gap covering the whole brain, including the cerebellum. The other imaging parameters will be as follows: FOV = 24 x 24 cm2, matrix size 128 x 128, thus the voxel size = 1.8 x 1.8 x 3 mm3. The total scanning time for the DTI acquisition will be approximately 11 minutes.
fMRI sequences will be performed using T2*-weighted echo-planer imaging sequence at TR = 2000ms, TE = 35ms, flip angle = 90°, field of view = 240 mm, matrix size = 64x64, slice thickness = 4 mm, and zero gap covering whole brain. The orientation of the axial slice will be set to be parallel to the AC-PC line. The total scanning time for one fMRI study will be about 4~7 minutes depending on the experimental protocol.
Participants will be asked to do several tasks while completing the fMRI portion of the proposed study. In order to assess motor activation, participants will be asked to tap their index finger from each hand separately. This will be compared with a rest condition. Additionally, participants will also do receptive and expressive language tasks. fMRI tasks are described below.
fMR Protocol Descriptions:
1)Motor Right Hand - For this task the patient opens and closes her right hand for 20” alternating with 20” of rest (six cycles). 2)Motor Left Hand - For this task the patient opens and closes her left hand for 20” alternating with 20” of rest (six cycles). 3)Semantic Language Processing – The patient answers questions (yes/no) about colored shapes presented visually. The control condition involves determination (yes/no) about whether two shapes (the first and last in a series) are the same while listening to a series of tones. 4)Expressive Language Processing – The patient determines whether two words or nonwords rhyme; whether two words have the same meaning; rest conditions.
Neuropsychological Evaluation. The specific neurocognitive battery includes evaluation of the following domains: global, verbal and nonverbal intellectual, language processing, verbal and visual memory, executive and motor functioning, and behavioral functioning (internalizing and externalizing). All of the measures in the study have been widely used in research and clinical populations, and have been demonstrated to have good psychometric properties (Kongs, Thompson, Iverson, & Heaton, 2003; Sattler, 2004; Sheslow & Adams, 2003).
All study group participants will receive all of the following components: 1) MRI scan with DTI and SPGR sequences, 2) fMRI imaging 3) a comprehensive neurocognitive and behavioral evaluation.
We can cover gas costs and, if necessary, one night at the International Guest House adjacent to Children’s hospital.