Changes in brain function and anatomical structure following treatment of hyperbaric oxygen for visual pathway abnormalities in 16 cases Evaluation of functional magnetic resonance imaging combined with diffusion tensor imaging

BACKGROUND： There is a growing research focus on the combination of blood oxygenation level dependent functional magnetic resonance imaging （BOLD-fMRI） and diffusion tensor imaging （DTI） to evaluate visual cortical function and structural changes in the cerebrum, as well as morphological changes to the white matter fiber tracks, after visual pathway lesions. However, the combined application of BOLD-fMRI and DTI in treating of visual pathway abnormalities still requires further studies. OBJECTIVE： To observe and evaluate the effects of hyperbaric oxygen on visual pathway abnormalities, and to evaluate the characteristics of cerebral function and anatomic structural changes by using BOLD-fMRI combined with DTI technique. DESIGN： Case contrast observation. SETTING： Fuzhou General Hospital of Nanjing Military Area Command of Chinese PLA. PARTICIPANTS： Sixteen patients （9 males and 7 females, 15-77 years old） with lateral or bilateral visual disorder induced by visual pathway lesions were selected from the Department of Neurology, Fuzhou General Hospital of Nanjing Military Area Command of Chinese PLA from January 2006 to May 2007. These patients comprised the lesion group. Measures of interventional therapy： hyperbaric oxygen of two normal atmospheres for three courses （10 d/course） and routine internal medicine treatment. In addition, 12 healthy subjects of similar sex and age to the lesion group were regarded as the control group. The control group underwent routine ophthalmological and ocular fundus examinations; diagnostic results were normal. The experiment received confirmed consent from the local ethic committee, and all patients provided informed consent. METHODS： BOLD-fMRI and DTI manifestations in the lesion group were observed before and after hyperbaric oxygen intervention, and the results were compared with the control group. The subjects were positioned on their back, and BOLD-fMRI images were collected with the following GRE EPI sequence： TR = 2 000 ms, TE = 40 ms, layer thickness = 5 mm, and 20-layer successive scanning to cover the whole brain. While, DTI images were collected with SE EPI sequence of single excitation： TR=10 000 ms, TE = 112 ms, layer thickness = 4 mm, layer spacing = 0.5 mm, and a 30-layer successive scanning, matrix = 128×128. A diffusion gradient was applied at 13 directions, and one layer without diffusion weighted imaging was collected at b =1 000 s/mm^2. Numbers of activated voxels in cortical-activated regions, and fractional anisotropy in bilateral cerebral optical radiation regions, were calculated. Displacement, continuity, and destruction of fibrous tracts were analyzed. MAIN OUTCOME MEASURES： Results of BOLD-fMRI and DTI examinations. RESULTS： All 16 patients and 12 controls were included in the final analysis. ① Numbers of activated voxels through the use of BOLD-fMRI： prior to hyperbaric oxygen therapy, the number of activated voxels in the bilateral cortex of occipital lobe were significantly less in the lesion group than in the control group （t =3.23, P 〈 0.01）. In addition, the number of activated voxels significantly increased after treatment compared to before treatment （t = 2.46, P 〈 0.05）. ② Fractional anisotropy in optical radiation regions of bilateral cerebrum： fractional anisotropy in the lesion group was significantly less than the control group （t =2.89, P 〈 0.05）. In addition, fractional anisotropy after treatment was significantly higher than before treatment （t = 2.48, P 〈 0.05）. Moreover, fractional anisotropy of optical neuropathy was significantly higher in 6 patients in the lesion group than the occipital lobe optical central lesion （t = 2.35, P 〈 0.05）. CONCLUSION： BOLD-fMRI combined with DTI can indicate the occurrence, development, and therapeutic course of action for optical pathway lesions. The results acquired from these methods can provide information for function and structure, which can provide reliable verification in the treatment of cerebral function.

Characters of MR diffusion tensor imaging in cerebral ischemic corticospinal tract injury

BACKGROUND： Diffusion tensor imaging （DTI） is one of the noninvasive methods to study the morphological structure of brain white matter fibrous bands in vivo, and it has been applied primarily in clinic. DTI is acknowledged as the more effective imaging method to diagnose ultra-acute and/or acute cerebral infarction.OB_3ECTIVE： To observe the anisotropic characters of cerebral white matter fibrous bands in patients with ischemic stroke by using DTI, and investigate the correlation between the damage of corticospinal tract and muscle strength in patients with ischemic stroke at acute period.DESIGN： A case-control observationSEFIING： Department of Medical Imaging, Fuzhou General Hospital of Nanjing Military Area Command of Chinese PLA.PARTICIPANTS： Nine inpatients with injury of motor function induced by acute ischemic stroke （patient group） at 6 hours to 2 weeks after the attack were selected from the Department of Neurology, Fuzhou General Hospital of Nanjing Military Area Command of Chinese PLA from September 2005 to March 2006, and they all accorded with the present diagnostic standard for cerebrovascular disease in China. There were 5 males and 4 females, aged 16-87 years. At the same time, nine healthy right-handed physical examinees matched by age and sex with the patients were taken as the control group, and they all had no nervous disease, mental diseases, cerebrovascular abnormalities and injury history, etc. All the subjects were informed with the detected items and agreed to participate in the study.METHODS： All the 9 patients with ischemic stroke at acute period and 9 healthy subjects were examined with MRI, T1 weighted imaging, T2 weighted imaging and DTI. And the data were processed offline with dTV.II software, the images of fractional anisotropy and directional encoded color （DEC） were obtained, and the three-dimensional fibrous band images of bilateral corticospinal tracts were reconstructed. In the control group, the values of fractional anisotropy of main white matter fibrous bands were measured in the region of interest （ROI） of the anterior limb, knee and posterior limb of internal capsule. In the patient group, the values of fractional anisotropy of white matter were measured in the infarcted sites and corresponding contralateral sites of the patients. The ROI was set in bilateral cerebral peduncles to reconstruct three-dimensionally the bilateral corticospinal tracts. The muscle strength of the affected hand was assessed with Brunnstorm standard in the stroke patients.MAIN OUTCOME MEASURES ： The characters of DTI and images of the value of fractional anisotropy, and the manifestations of three-dimensional corticospinal tracts were observed in the two groups.RESULTS： All the data from the 9 patients and 9 healthy volunteers were involved in the analysis of results. In the control group, the white matter and gray matter could be distinguished clearly in the image of fractional anisotropic values, the fibers of different directions were shown by different colors in DEC picture, which clearly demonstrated the normal anatomic structure and direction of white matter fibers. In the patient group, the infarctions occurred in the gray matter or white matter could be distinguished in the images of fractional anisotropic values, DEC picture could clearly show the direct influence of the infarcted site on the white matter fibers. The fractional anisotropic values in different white matter structure of the same side were significantly different in the control group （t=-3.12, P 〈 0.05）, and the reconstructed images fractional anisotropic values and DEC picture could show most of the main white matter fibrous bands. The fractional anisotropic values of the infarcted sites were significantly lower than the contralateral ones in the patient group （t=-5.570, P 〈 0.01）. ② The reconstructed bilateral corticospinal tracts showed that the anatomic forms of the contralateral corticospinal tract of the patients were almost identical to those of normal people, it started from precentral gyrus, downward to the nternal capsule, and extended to pontine and medulla oblongata, each fibrous band was continuous, and the form had good consistency. Because of the involvement of infarction of different severity, the ipsilateral corticospinal tract manifested as continuous interruption and the loss of consistent anatomic structural form. The involved severity of corticospinal tract had significant correlation with that of muscle strength of the ipsilateral hand （r=-1.30, P 〈 0.01）.CONCLUSION： ① DTI can display the direction and distribution of cerebral white matter fibrous bands.② DTI images of fractional anisotropic values and DEC can show the directions and anisotropic degree of white matter fibers in the infarcted sites of stroke patients. ③ The three-dimensional images of fibrous bands can show the conditions of pyramidal tracts more directly. ④ The damaged severity of corticospinal tracts is correlated with that of muscle strength.

Observation of activation status of motor-related cortex of patients with acute ischemic stroke through functional magnetic resonance imaging

BACKGROUND： About more than three fourth of patients with stroke have motor dysfunction at different degrees, especially hand motor dysfunction. Functional magnetic resonance imaging （fMRI） provides very reliable visible evidence for studying central mechanism of motor dysfunction after stroke, and has guiding and applicable value for clinical therapy. OBJECTIVE： To observe the activation of motor-related cortex of patients with acute ischemic stroke with functional magnetic resonance imaging, and analyze the relationship between brain function reconstruction and motor restoration after stroke. DESIGN ： A contrast observation SETTING： Medical Imaging Center, Fuzhou General Hospital of Nanjing Military Area Command of Chinese PLA. PARTICIPANTS ： Nine patients with acute ischemic stroke who suffered from motor dysfunction and received the treatment in the Fuzhou General Hospital of Nanjing Military Area Command of Chinese PLA between August and December 2005 were recruited, serving as experimental group. The involved patients including 5 male and 4 female, aged 16 to 87 years, all met the diagnostic criteria of cerebrovascular disease revised by The Fourth National Conference on Cerebrovascular Disease, mainly presenting paralysis in clinic, and underwent fMRI. Another 9 right handed persons matched in age and gender who simultaneously received healthy body examination were recruited, serving as control group. All the subjects were informed of the detected items. METHODS ： ①Muscular strength of patients of the experimental group was evaluated according to Brunnstrom grading muscular strength （Grade Ⅰ -Ⅳ）. ②Passive finger to finger motion was used as the mission （alternate style of quiescence, left hand motion and quiescence, nght hand motion was repeated 3 times, serving as 1 sequence, 20 s per block and 20 s time interval. The whole process of scanning was 260 s）, and subjects of 2 groups were given Bold-fMRI examination with GEl .5T double gradient 16-channel magnetic resonance imaging system. All the data were given off-line management, and fMRI was treated with SPM2 softwere. The activation of passive finger-to-finger motion-related cortex of subjects in 2 groups was observed. ③ Results of fMRI of subjects in 2 groups were compared. The size of activation region of brain and signal intensity were measured and unilateral index was calculated. The data of activation region of cerebral hemisphere of different sides at finger motion were given statistical analysis of unilateral index. Differences among unilateral indexes at hand motion were compared between intact and affected hands of patients in experimental group. The relationship between unilateral index and muscular strength of affected hands at affected hand motion in patients of the experimental group was performed Spearman correlation analysis. MAIN OUTCOME MEASURES： ① The activation of motion-related cortex passive finger-to-finger motion between handedness and non-handedness was detected with functional magnetic resonance imaging of subjects in 2 groups. ②Relationship between unilateral index and muscular strength of subjects of experimental group at affected hand motion. RESULTS： Nine patients with ischemic stroke and 9 controls all participated in the final result analysis. ① Passive fMRI detection results between handedness and non-handedness of controls： Right-handed finger-to-finger motion of subjects of control group mainly activated contralateral sensonmotor cortex, and left-handed finger-to-finger motion not only activated above-mentioned brain region, but also activated supplementary motor area （SMA） of contralateral brain region; ②In the experimental group, sensorimotor cortex of contralateral hemisphere was activated at affected hand motion, and homolateral posterior parietal cortex （PPC）was also obviously activated. Bilateral sensonmotor cortex was activated at affected hand motion in 2 patients, and homolateral activation area was larger than contralateral one. At intact hand motion, contralateral sensorimotor cortex was activated, but no obvious homolateral activation area was found. ③ Correlation of unilateral index with muscular strength： Passive finger-to-finger fMRI （ between affected and intact hands of subjects of experimental group： Unilateral index at passive single finger motion of affected and intact hand of subjects of experimental group was -0.018±0.01 and 0.319±0.187, respectively, with significant difference （t=4.059, P 〈 0.01 ）. Unilateral index was significantly positively correlated with the muscular strength of affected hand at affected hand motion（r=0.834, P 〈 0.05）.CONCLUSION ： ①fMRI can objectively shows different activation states of motor cortex between patients with ischemic stroke and healthy controls, and brain functional compensation and recombination exist. Both primary sensorimotor cortex and SMA of bilateral hemispheres participant in affected hand motion, at the same time, parietal lobe and cortex of intact side also obviously participant in the affected hand motion. ②Correlation analysis of unilateral index and muscular strength of affected hand performed through fMRI can be used as an effective means to investigate the relationship between motion rehabilitation and brain functional recombination after stroke.

Evaluating ischemic stroke with diffusion tensor imaging

Objective:In recent years,diffusion tensor imaging (DTI) has emerged as a promising tool to study ischemic stroke. The aim of this study is to evaluate the anisotropic changes of cerebral white matter tracks in patients with ischemic stroke using DTI,and investigate the correlation between corticospinal tract damage and muscle strength in such patients during acute ischemia.Method:9 patients with acute ischemic stroke and 9 healthy subjects were examined with T1 weighted magnetic resonance imaging (MRI),T2 weighted MRI and DTI. Fractional anisotropy (FA) was measured and the three-dimensional fibrous band images of bilateral corticospinal tracts were reconstructed. The muscle strength of the affected hand was assessed by Brunnstorm standard[1],which is an internationally recognized measure of movement in hemiplegic patients.Results:①In the control group,there was no significant difference in FA between the bilateral corticospinal tracts,but FA in different white matter structure of the same side was significantly different (t=3.12,P < 0.05). FA of posterior limb of internal capsule was higher than that of knee and anterior limb of internal capsule,FA of anterior limb of internal capsule was the lowest. while in the patient group,FA of the infarcted sites was significantly lower than the contralateral ones (t=5.570,P < 0.01). ②The ipsilateral corticospinal tract demonstrated continuous interruption and the loss of consistent anatomic structure. The involved severity of corticospinal tract had significant correlation with that of muscle strength of the ipsilateral hand (r=0.83,P < 0.01).Conclusion:This study shows that DTI can be used to investigate ischemic stroke and assess ischemic stroke-induced damage. The damaged severity of corticospinal tracts is correlated with that of muscle strength.