Do-Wan Lee

Topographic organization of motor fibre tracts in the human brain: findings in multiple locations using magnetic resonance diffusion tensor tractography

AbstractObjectivesTo identify the hand and foot fibre tracts of the corticospinal tract (CST), and to evaluate the relative locations, angles, and distances of two fibre tracts using diffusion tensor tractography (DTT).MethodsTwelve healthy subjects were enrolled. The regions of interests (ROIs) were drawn in the functional magnetic resonance imaging (fMRI) activation areas and pons in each subject for fibre tracking. We evaluated fibre tract distributions using distances and angles between two fibre tracts starting from the location of a hand fibre tract in multiple brain regions.ResultsThe measured angles and distances were 96.43–150°/2.69–9.93xa0mm (upper CR), 91.86–180°/1.63–7.42xa0mm (lower CR), 54.47–75°/0.75-4.45xa0mm (PLIC), and 3.65–90°/0.11–2.36xa0mm (pons), respectively. The distributions between CR and other sections, such as PLIC and pons, were statistically significant (pu2009<u20090.05). There were no significant differences between the upper and lower CR or between the PLIC and pons.ConclusionsThis study showed that the somatotopic arrangement of the hand fibre tract was located at the anterolateral portion in CR and at the anteromedial portion in PLIC and pons, based on the foot fibre. Our methods and results seem to be helpful in motor control neurological research.Key points• We evaluated somatotopic arrangement of CST at multiple anatomical locations.n • Somatotopic arrangements and fibre tract distributions were evaluated based on hand fibre location.n • Relative angles, locations, and distances between two fibres vary according to their anatomical locations.

Symmetrical Location Characteristics of Corticospinal Tract Associated With Hand Movement in the Human Brain: A Probabilistic Diffusion Tensor Tractography

AbstractThe purpose of this study is to elucidate the symmetrical characteristics of corticospinal tract (CST) related with hand movement in bilateral hemispheres using probabilistic fiber tracking method.Seventeen subjects were participated in this study. Fiber tracking was performed with 2 regions of interest, hand activated functional magnetic resonance imaging (fMRI) results and pontomedullary junction in each cerebral hemisphere. Each subjects extracted fiber tract was normalized with a brain template. To measure the symmetrical distributions of the CST related with hand movement, the laterality and anteriority indices were defined in upper corona radiata (CR), lower CR, and posterior limb of internal capsule.The measured laterality and anteriority indices between the hemispheres in each different brain location showed no significant differences with Pu200a<u200a0.05. There were significant differences in the measured indices among 3 different brain locations in each cerebral hemisphere with Pu200a<u200a0.001. Our results clearly showed that the hand CST had symmetric structures in bilateral hemispheres.The probabilistic fiber tracking with fMRI approach demonstrated that the hand CST can be successfully extracted regardless of crossing fiber problem. Our analytical approaches and results seem to be helpful for providing the database of CST somatotopy to neurologists and clinical researches.

Possibility Study of Scale Invariant Feature Transform (SIFT) Algorithm Application to Spine Magnetic Resonance Imaging.

The purpose of this study is an application of scale invariant feature transform (SIFT) algorithm to stitch the cervical-thoracic-lumbar (C-T-L) spine magnetic resonance (MR) images to provide a view of the entire spine in a single image. All MR images were acquired with fast spin echo (FSE) pulse sequence using two MR scanners (1.5 T and 3.0 T). The stitching procedures for each part of spine MR image were performed and implemented on a graphic user interface (GUI) configuration. Moreover, the stitching process is performed in two categories; manual point-to-point (mPTP) selection that performed by user specified corresponding matching points, and automated point-to-point (aPTP) selection that performed by SIFT algorithm. The stitched images using SIFT algorithm showed fine registered results and quantitatively acquired values also indicated little errors compared with commercially mounted stitching algorithm in MRI systems. Our study presented a preliminary validation of the SIFT algorithm application to MRI spine images, and the results indicated that the proposed approach can be performed well for the improvement of diagnosis. We believe that our approach can be helpful for the clinical application and extension of other medical imaging modalities for image stitching.

Brodmann’s Area Template Based Region of Interest Setting and Probabilistic Pathway Map Generation in Diffusion Tensor Tractography: Application to the Arcuate Fasciculus Fiber Tract in the Human Brain

The purpose of this study is to acquire accurate diffusion tensor tractography (DTT) results for arcuate fasciculus (AF) fiber tract using Brodmann’s area (BA) template for region of interest (ROI) setting. Thirteen healthy subjects were participated in this study. Fractional anisotropy (FA) map of each subject was calculated using diffusion tensor data, and T1w template was co-registered to FA map. The BA template was also co-registered using the transformation matrix. The ROIs were drawn in the co-registered BA template, and AF fiber tract was extracted. To generate the probabilistic pathway map, a binary mask image was generated based on the fiber tract image and co-registered to T1w template image. We also measured relative location of the AF fiber tract. The location of the probabilistic pathway map of each subject’s AF fiber tract was well defined in the brain. By using this probabilistic map, the mediolateral position ratio of AF was measured 18%, and the anteroposterior position ratio of AF was measured 35%, respectively. This study demonstrated that the AF fiber tract can be extracted using BA template for ROI setting and probabilistic pathway of fiber tract. Our results and analytical approaches can helpful for accurate fiber tracking and application of perspective clinical researches.

Simple image intensity compensation SIMIC method prior to application of distortion correction algorithms in brain diffusion Tensor Magnetic Resonance Imaging: Validation test for two cost functions of distortion correction algorithms

The purpose of this study is to design a simple image intensity compensation (SIMIC) method prior to the application of a variety of cost functions for distortion correction in diffusion tensor imaging (DTI). The synthetic dataset consists of each direction of diffusion weighted imaging (DWI) made by multiplication of nondiffusion weighted image (b = 0 image) and tensor matrices. We added the effects of patient motion and eddy current distortion using translation, rotation, scaling and shearing matrices. We calculated the b = 0 image of each direction from original DTI, inversely. A co‐registration method was applied to the extracted b = 0 images of each direction based on the original b = 0 image and then, the transformation matrices were generated and the original DTI were transformed using this transformation matrix. For the DTI distortion correction, two kinds of cost functions, normalized mutual information (NMI) and normalized cross‐correlation (NCC), were used. Visual assessments and quantitative measurements were used to evaluate the results. When using the NMI as a cost function, the quantitative results showed no significant differences between NMI and NMI with SIMIC method. However, there are significant differences compared with using the NCC as a cost function. Our study showed cost function for image distortion correction with SIMIC method improved the results both quantitatively and in terms of qualitative accuracy. This method may be helpful for DTI analysis and helpful for increasing accuracy.

1474PRANDOMIZED PHASE II STUDY OF BELOTECAN OR TOPOTECAN CHEMOTHERAPY AS SECOND-LINE CHEMOTHERAPY AFTER PLATINUM-BASED FIRST-LINE CHEMOTHERAPY FOR SMALL CELL LUNG CANCER

ABSTRACT Aim: Topotecan has been accepted as second-line therapy for small cell lung cancer (SCLC), in addition, belotecan also been reported to have a significant response rate. Based on these results, we designed prospective randomized phase II trial of belotecan as a second-line treatment in patients with SCLC, who experienced disease progression within 6 months after first-line platinum-containing chemotherapy or chemo-radiotherapy. Methods: We randomly assigned patients to belotecan 0.5 mg/m2 (n=61) or topotecan 1.5 mg/m2 (n=55) for 5 days every 21 days, stratified by response to first-line chemotherapy. The primary end point was response rate (RR). The secondary end points were progression-free survival (PFS), overall survival (OS) and safety profiles. Results: From August 2006 to December 2013, a total of 116 patients were enrolled. The median age was 64 years (range, 28-82), and the ratio of males to females was 0.89. In total, 186 cycles of topotecan (median 2, range 1-9) and 180 cycles of belotecan (median 2, range 1-8) were administered. Median follow-up was 5.6 months. RR of belotecan and topotecan was 19.7% (12/61) and 18.2% (10/55), respectively (p=0.92). Median PFS and OS of belotecan and topotecan was 2.1 months (95% CI 1.43-2.72) versus 2.3 months (1.46-3.07) and 11.2 months (10.2-12.1) versus 12.1 months (10.1-14.0), respectively (p=0.167, 0.659). Grade 3/4 hematologic adverse events with belotecan and topotecan were anemia [13.1% versus 14.5% (p=1.000)] thrombocytopenia [3.3% versus 7.3% (p=0.421)], neutropenia [21.3% versus 43.6% (p=0.016)]. Conclusions: Belotecan showed comparable efficacy to that with topotecan and more favorable toxicity profiles for neutropenia. Disclosure: All authors have declared no conflicts of interest.

In Vivo Mapping and Quantification of Creatine Using Chemical Exchange Saturation Transfer Imaging in Rat Models of Epileptic Seizure

PurposeTo evaluate signal changes in the hippocampus of epileptic seizure rat models, based on quantified creatine chemical exchange saturation transfer (CrCEST) signals.ProceduresCEST data and 1H magnetic resonance spectroscopy (1H MRS) data were obtained for the two imaging groups: control (CTRL) and epileptic seizure-induced (ES; via kainic acid [KA] injection) groups. CrCEST signals in the hippocampal regions were quantitatively evaluated; correlations between CrCEST signals and phosphocreatine (PCr) and total creatine (tCr; PCru2009+u2009Cr) concentrations, derived from the analysis of 1H MRS data, were investigated as a function of time changes (before KA injection, 3 and 5xa0h after KA injection).ResultsMeasured CrCEST signals were exhibited significant differences between before and after KA injection in the ES group. At each time point, CrCEST signals showed significant correlations with PCr concentration (all |r|u2009>u20090.59; all Pu2009<u20090.05); no significant correlations were found between CrCEST signals and tCr concentrations (all |r|u2009<u20090.22; all Pu2009>u20090.05).ConclusionsCrCEST can adequately detect changes in the concentration of Cr as a result of energy metabolism, and may serve as a potentially useful tool for diagnosis and assessment of prognosis in epilepsy.

Minimisation of Signal Intensity Differences in Distortion Correction Approaches of Brain Magnetic Resonance Diffusion Tensor Imaging

ObjectivesTo evaluate the effects of signal intensity differences between the b0 image and diffusion tensor imaging (DTI) in the image registration process.MethodsTo correct signal intensity differences between the b0 image and DTI data, a simple image intensity compensation (SIMIC) method, which is a b0 image re-calculation process from DTI data, was applied before the image registration. The re-calculated b0 image (b0ext) from each diffusion direction was registered to the b0 image acquired through the MR scanning (b0nd) with two types of cost functions and their transformation matrices were acquired. These transformation matrices were then used to register the DTI data. For quantifications, the dice similarity coefficient (DSC) values, diffusion scalar matrix, and quantified fibre numbers and lengths were calculated.ResultsThe combined SIMIC method with two cost functions showed the highest DSC value (0.802 ± 0.007). Regarding diffusion scalar values and numbers and lengths of fibres from the corpus callosum, superior longitudinal fasciculus, and cortico-spinal tract, only using normalised cross correlation (NCC) showed a specific tendency toward lower values in the brain regions.ConclusionImage-based distortion correction with SIMIC for DTI data would help in image analysis by accounting for signal intensity differences as one additional option for DTI analysis.Key points• We evaluated the effects of signal intensity differences at DTI registration.• The non-diffusion-weighted image re-calculation process from DTI data was applied.• SIMIC can minimise the signal intensity differences at DTI registration.

Neurochemical Changes Associated with Stress-Induced Sleep Disturbance in Rats: In Vivo and In Vitro Measurements

The goal of this study was to quantitatively assess the changes in the cerebral neurochemical profile and to identify those factors that contribute to the alteration of endogenous biomolecules when rats are subjected to stress-induced sleep disturbance. We exposed Sprague-Dawley rats (controls: n = 9; stress-induced sleep perturbation rats: n = 11) to a psychological stressor (cage exchange method) to achieve stress-induced sleep perturbation. In vivo magnetic resonance imaging assessments were carried out using a high-resolution 9.4 T system. For in vivo neurochemical analysis, a single voxel was localized in the right dorsal hippocampal region, and in vivo spectra were quantified for 17 cerebral neurochemical signals. Rats were sacrificed upon completion of the magnetic resonance spectroscopy protocol, and whole-brain tissue was harvested from twenty subjects. The dopamine and serotonin signals were obtained by performing in vitro liquid chromatography-tandem mass spectrometry on the harvested tissue. In the right dorsal hippocampal region, the gamma-aminobutyric-acid (GABA) and glutamine (Gln) concentrations were significantly higher in the sleep-perturbed rats than in the sham controls. The ratios of Gln/Glu (glutamate), Gln/tCr (total-creatine), and GABA/Glu were also significantly higher in the sleep-perturbed group, while serotonin concentrations were significantly lower in the sleep-perturbed rats. Pearson correlation results among individual rat data indicate that concentrations of dopamine (DA) and serotonin (5-HT) were significantly higher in SSP rats. A larger correlation coefficient was also observed for the SSP rats. Analysis of the correlation between the in vivo and in vitro signals indicated that the concentrations of Gln, 5-HT, and DA exhibited a significant negative correlation in the SSP rat data but not in that of control rats. The authors propose that the altered and correlated GABA, Gln, 5-HT, and DA concentrations/ratios could be considered key markers of neurological function in animal models of stress-induced sleep perturbation.