[Show abstract][Hide abstract] ABSTRACT: Images obtained through ultra-high field 7.0T MRI with track-density imaging (TDI) provide clear and high resolution tractograms that have been hitherto unavailable, especially in deep brain areas such as the limbic and thalamic regions. Using this recently developed technique, we have identified four fiber tracts that have not previously been directly visualized in-vivo: the septum pellucidum tract (SPT), the anterior thalamic radiation (ATR), the superolateral medial forebrain bundle (slMFB), and the inferomedial forebrain bundle (imMFB). This is a largely pictorial description based on the new track density images we have obtained through 7.0T MRI with DWI-TDI. To identify the fiber tracts we selected three sets of tractograms and performed inter-axis correlation between them. These tractograms offer an opportunity for readers to extract new information, especially in the thalamo-limbic areas, which have previously been difficult to examine using either in-vivo or in-vitro human brain tractography. We present the high resolution images as a tool for researchers and clinicians working with neurodegenerative and psychiatric diseases such as Parkinson's Disease, Alzheimer's Disease, and depression, in which the accurate positioning of deep brain stimulation (DBS) is essential for precise targeting of nuclei and fiber tracts.
[Show abstract][Hide abstract] ABSTRACT: Background: Diffusion tensor imaging (DTI) reflects the maturation of the brain microstructure. Although preterm infants are at significant risk for altered brain microstructure, it remains unclear whether this is affected by prematurity itself or other clinical factors. Objectives: To investigate DTI parameters in preterm infants at a term-equivalent age (TEA) compared with healthy term infants and to assess the associations between DTI parameters and clinical factors that may affect brain development. Methods: We studied 34 preterm infants without apparent brain lesions and 12 healthy term infants using tract-based spatial statistics. Region-of-interest analysis was performed in the posterior and anterior limbs of the internal capsule (PLIC and ALIC), corpus callosum (CC), optic radiation, and cerebral peduncle. Results: Preterm infants had significantly decreased fractional anisotropy (FA) in nearly the entire white matter (WM) compared with term infants (p < 0.01). Multiple regression analysis showed that FA in the PLIC, ALIC, optic radiation, and cerebral peduncle were positively associated with postmenstrual age (PMA) at imaging and that the apparent diffusion coefficient was negatively associated with PMA. Only FA in the CC was positively correlated with gestational age. Chronic lung disease (CLD) and postnatal infection were associated with decreased FA in the CC and PLIC, respectively. Conclusions: Preterm infants at TEA showed an altered microstructure of the WM compared with healthy term infants. The altered microstructure of the measured WM except the CC was independent of the degree of prematurity. Chronic lung disease and postnatal infection are related to localized WM alterations.
[Show abstract][Hide abstract] ABSTRACT: To investigate anatomical changes in the substantia nigra (SN) of Parkinson disease (PD) patients with age-matched controls by using ultra-high field magnetic resonance imaging (MRI).
We performed 7T MRI in 10 PD and 10 age-matched control subjects. Magnetic resonance images of the SN were obtained from a 3-dimensional (3D) T(2)*-weighted gradient echo sequence. Region of interest-based 3D shape analysis was performed to quantitatively compare images from the 2 groups.
The boundary between the SN and crus cerebri was not smooth in PD subjects. Undulation in the lateral surface of the SN appeared more intense in the side contralateral to that with the more severe symptoms, and more prominent at the rostral level of the SN than at the intermediate or caudal levels. In addition to the lateral surface, there was a striking difference in the dorsomedial aspects of the SN between PD and control subjects. In control subjects, a brighter signal region was observed along the dorsomedial surface of the lateral portion of SN, whereas in PD subjects, this region was observed as a dark region containing a hypointense signal in T(2)*-weighted images. The measurement of SN volumes, normalized to the intracranial volumes, showed higher values in PD subjects than in control subjects.
This study demonstrates that 3D 7T MRI can definitively visualize anatomical alterations occurring in the SN of PD subjects. Further pathological studies are required to elucidate the nature of these anatomical alterations.
Annals of Neurology 02/2012; 71(2):267-77. · 11.91 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Autism has been hypothesized to reflect neuronal disconnection. Several recent reports implicate the key thalamic relay nuclei and cortico-thalamic connectivity in the pathophysiology of autism. Accordingly, we aimed to focus on evaluating the integrity of the thalamic radiation and sought to replicate prior white matter findings in Korean boys with high-functioning autism spectrum disorders (ASD) using Diffusion Tensor Imaging (DTI).
We compared fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD) and radial diffusivity (RD) in 17 boys with ASD and 17 typically developing controls in the anterior thalamic radiation (ATR), superior thalamic radiation (STR), posterior thalamic radiation (PTR), corpus callosum (CC), uncinate fasciculus (UF) and inferior longitudinal fasciculus (ILF).
The two groups were group-matched on age, IQ, handedness and head circumference. In whole-brain voxel-wise analyses, FA was significantly reduced and MD was significantly increased in the right ATR, CC, and left UF in subjects with ASD (p<0.05, corrected). We found significantly lower FA in right and left ATR, CC, left UF and right and left ILF and significantly higher MD values of the CC in the ASD group in region of interest-based analyses. We also observed significantly higher RD values of right and left ATR, CC, left UF, left ILF in subjects with ASD compared to typically developing boys and significantly lower AD values of both ILF. Right ATR and right UF FA was significantly negatively correlated with total SRS score within the ASD group (r=-.56, p=.02).
Our preliminary findings support evidence implicating disturbances in the thalamo-frontal connections in autism. These findings highlight the role of hypoconnectivity between the frontal cortex and thalamus in ASD.
Brain research 08/2011; 1417:77-86. · 2.83 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Parkinson's disease (PD) is a neurodegenerative disorder resulting from progressive loss of dopaminergic neurons in the substantia nigra (SN) pars compacta. Therefore, imaging of the SN has been regarded to hold greatest potential for use in the diagnosis of PD. At the 7.0T magnetic resonance imaging (MRI), it is now possible to delineate clearly the shapes and boundaries of the SN. We scanned eight early and two advanced PD patients, along with nine age-matched control subjects, using a 7.0T MRI in an attempt to directly visualize the SN and quantify the differences in shape and boundaries of SN between PD subjects in comparison with the normal control subjects. In the normal controls, the boundaries between the SN and crus cerebri appear smooth, and clean "arch" shapes that stretch ventrally from posterior to anterior. In contrast, these smooth and clean arch-like boundaries were lost in PD subjects. The measured correlation analyses show that, in PD patients, there is age-dependent correlation and substantially stronger UPDRS motor score-dependent correlation. These results suggest that, by using 7.0T MRI, it appears possible to use these visible and distinctive changes in morphology as a diagnostic marker of PD.
Movement Disorders 03/2011; 26(4):713-8. · 5.63 Impact Factor