Wen-Bin Li

Dynamics of Rabbit Brain Edema in Focal Lesion and Perilesion Area after Traumatic Brain Injury: A MRI Study

To understand the dynamics of brain edema in different areas after traumatic brain injury (TBI) in rabbit, we used dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) and diffusion-weighted imaging (DWI) to monitor blood-brain barrier (BBB) permeability and cytotoxic brain edema after weight drop-induced TBI in rabbit. The dynamics of BBB permeability and brain edema were quantified using K(trans) and apparent diffusion coefficient (ADC) in the focal and perifocal lesion areas, as well as the area contralateral to the lesion. In the focal lesion area, K(trans) began to increase at 3 h post-TBI, peaked at 3 days, and decreased gradually while remaining higher than sham injury animals at 7 and 30 days. ADC was more variable, increased slightly at 3 h, decreased to its lowest value at 7 days, then increased to a peak at 30 days. In the perifocal lesion area, K(trans) began to increase at 1 day, peaked at 3-7 days, and returned to control level by 30 days. ADC showed a trend to increase at 1 day, followed by a continuous increase thereafter. In the contralateral area, no changes in K(trans) and ADC were observed at any time-point. These data demonstrate that different types of brain edema predominate in the focal and perifocal lesion areas. Specifically cytotoxic edema was predominant in the focal lesion area while vasogenic edema predominated in the perifocal area in acute phase. Furthermore, secondary opening of the BBB after TBI may appear if secondary injury is not controlled. BBB damage may be a driving force for cytotoxic brain edema and could be a new target for TBI intervention.

The value of diffusion tensor imaging in the differential diagnosis of subcortical ischemic vascular dementia and Alzheimer's disease in patients with only mild white matter alterations on T2-weighted images.

Background Diffusion tensor imaging (DTI) is a form of functional magnetic resonance imaging (MRI) that allows examination of the microstructural integrity of white matter in the brain. Dementia is a neurodegenerative disease, and DTI can provide indirect insights of the microstructural characteristics of brains in individuals with different forms of dementia. Purpose To evaluate the value of DTI in the diagnosis and differential diagnosis of patients with subcortical ischemic vascular dementia (SIVD) and Alzheimers disease (AD). Material and Methods The study included 40 patients (20 AD patients and 20 SIVD patients) and 20 normal controls (NC). After routine MRI and DTI, fractional anisotropy (FA) and apparent diffusion coefficient (ADC) values were measured and compared in regions of interest (ROI). Results Compared to NC and AD patients, SIVD patients had lower FA values and higher ADC values in the inferior-fronto-occipital fascicles (IFOF), genu of the corpus callosum (GCC), splenium of the corpus callosum (SCC), and superior longitudinal fasciculus (SLF). Compared to controls and SIVD patients, AD patients had lower FA values in the anterior frontal lobe, temporal lobe, hippocampus, IFOF, GCC, and CF; and higher ADC values in the temporal lobe and hippocampus. Conclusion DTI can be used to estimate the white matter impairment in dementia patients. There were significant regional reductions of FA values and heightened ADC values in multiple regions in SIVD patients compared to AD patients. When compared with conventional MRI, DTI may provide a more objective method for the differential diagnosis of SIVD and AD disease patients who have only mild white matter alterations on T2-weighted imaging.

An Investigation of Age-Related Iron Deposition Using Susceptibility Weighted Imaging

Aim To quantify age-dependent iron deposition changes in healthy subjects using Susceptibility Weighted Imaging (SWI). Materials and Methods In total, 143 healthy volunteers were enrolled. All underwent conventional MR and SWI sequences. Subjects were divided into eight groups according to age. Using phase images to quantify iron deposition in the head of the caudate nucleus and the lenticular nucleus, the angle radian value was calculated and compared between groups. ANOVA/Pearson correlation coefficient linear regression analysis and polynomial fitting were performed to analyze the relationship between iron deposition in the head of the caudate nucleus and lenticular nucleus with age. Results Iron deposition in the lenticular nucleus increased in individuals aged up to 40 years, but did not change in those aged over 40 years once a peak had been reached. In the head of the caudate nucleus, iron deposition peaked at 60 years (p<0.05). The correlation coefficients for iron deposition in the L-head of the caudate nucleus, R-head of the caudate nucleus, L-lenticular nucleus and R-lenticular nucleus with age were 0.67691, 0.48585, 0.5228 and 0.5228 (p<0.001, respectively). Linear regression analyses showed a significant correlation between iron deposition levels in with age groups. Conclusions Iron deposition in the lenticular nucleus was found to increase with age, reaching a plateau at 40 years. Iron deposition in the head of the caudate nucleus also increased with age, reaching a plateau at 60 years.

A useful tool for the initial assessment of blood-brain barrier permeability after traumatic brain injury in rabbits: dynamic contrast-enhanced magnetic resonance imaging.

OBJECTIVE The aim of this study was to evaluate the role of dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) and its quantitative coefficient (K(trans)) in the assessment of the extent of traumatic brain injury (TBI) in a rabbit model. METHODS A weight-drop device (height, 20 cm) was used with varying impact force, 30-, 60-, or 90-g weight, to induce mild, moderate, or severe TBI, respectively. DCE-MRI and T2-weighted MRI was used to examine the injured groups and a sham group 1 day after TBI. We analyzed the relationship between K(trans) and the lesion volume on the basis of T2-weighted images in each group. RESULTS The lesion volumes in both the severe and the moderate injury groups were greater than those observed in the mild injury group (p < 0.01). Furthermore, the lesion volumes in the severe injury group tended to be greater than those seen in the moderate injury group (p = 0.053). The K(trans) values in all injury groups were greater than those observed in the sham group (p < 0.01). In addition, the K(trans) values in the severe and moderate injury groups were greater than those of the mild injury group (p < 0.01), and the values seen in the severe injury group tended to be greater than those of the moderate injury group (p = 0.08). Moreover, we observed a correlation between the K(trans) value and lesion volume in all injury groups (mild injury group: r = 0.766, p = 0.01; moderate injury group: r = 0.731, p = 0.04; and severe injury group: r = 0.886, p = 0.019). CONCLUSIONS DCE-MRI and its quantitative coefficient, K(trans), have the potential to accurately assess the blood-brain barrier and the extent of injury in an in vivo model of TBI.

Use of Diffusion Tensor Imaging for Evaluating Changes in the Microstructural Integrity of White Matter Over 3 Years in Patients with Amnesic-Type Mild Cognitive Impairment Converting to Alzheimer's Disease

Patients with amnestic mild cognitive impairment (aMCI) are at risk of developing Alzheimers disease (AD). It is therefore important to identify biomarkers of conversion to AD. This study examined whether the integrity of white matter can predict this conversion.

Detection of brain lesions at the skull base using diffusion-weighted imaging with readout-segmented echo-planar imaging and generalized autocalibrating partially parallel acquisitions

OBJECTIVE To analyze the value of readout-segmented echo-planar imaging (rs-EPI) with parallel imaging and a two-dimensional (2D) navigator-based reacquisition technique in the detection of brain lesions at the skull base. MATERIALS AND METHODS A total of 54 patients (male 37, female 17) with suspected skull-base intracranial lesions underwent magnetic resonance imaging (MRI), including pre-T1 weighted imaging, T2-weighted imaging, Fluid Attenuated Inversion Recovery (FLAIR), standard single shot echo-planar imaging diffusion weighted imaging (ss-EPI DWI) and rs-EPI DWI, post-contrast T1-weighted. The total number of lesions and the number of lesions at different sites on all MRI sequences were used as reference measures. Then differences in detecting lesions and image quality between standard ss-EPI DWI and rs-EPI DWI were analyzed. RESULTS There was a significant difference in the total number of lesions detected by rs-EPI DWI and standard ss-EPI DWI (P = 0.01). But this difference was mainly due to an improved ability of rs-EPI DWI to detect lesions located in the anterior cranial fossa, compared to ss-EPI DWI (P=0.02); the ability of ss-EPI and rs-EPI DWI to detect lesions in the middle cranial fossa and posterior cranial fossa was not significantly different (P = 0.471, P = 0.486, respectively). For image quality, rs-EPI images were significantly better than standard ss-EPI DWI images (P<0.001). CONCLUSION The rs-EPI DWI technique is a useful tool for the detection and evaluation of lesions located at the skull base.

Using susceptibility-weighted images to quantify iron deposition differences in amnestic mild cognitive impairment and Alzheimer's disease

AIM To quantify iron deposition in Alzheimers disease (AD), amnestic mild cognitive impairment (aMCI), and control individuals using susceptibility weighted imaging (SWI). MATERIALS AND METHODS Sixty participants (22 aMCI, 20 AD, 18 normal controls) underwent conventional magnetic resonance imaging (MRI) and SWI using axial/oblique coronal sequences. Phase images were used to calculate bilateral iron deposition in 18 regions of interest (ROI). The radian angle value was calculated and compared between the three participant groups. RESULTS The difference in radian angle value was significant between the aMCI and control groups in the left (L)-hippocampus, L-head of the caudate nucleus, R-lenticular nucleus, L-lenticular nucleus (P =0.02239, <0. 001, 0.03571, 0.00943, respectively). The difference in radian angle value was significant between the AD and aMCI groups in the R-cerebellar hemisphere, L-cerebellar hemisphere, R-hippocampus, L-hippocampus, R-red nucleus, R-thalamus, L-thalamus, and splenium of corpus callosum (P =0.02754, 0.01839, 0.00934, 0.04316, 0.02472, 0.00152, <0.001, 0.01448, respectively). Pearson correlation coefficients of the Mini-Mental State Examination score were all significant for the bilateral cerebellar hemisphere, hippocampus, red nucleus, lenticular nucleus, thalamus, R-head of the caudate nucleus, and splenium of corpus callosum. CONCLUSION Iron deposition in the hippocampus, head of the caudate nucleuslenticular nucleus, and thalamus are significantly different between individuals with aMCI, AD, and controls. The thalamus is a particularly sensitive area. Using SWI to quantify the iron deposition is a useful tool in detecting aMCI and AD.

Comparison of diffusion tensor image study in association fiber tracts among normal, amnestic mild cognitive impairment, and Alzheimer's patients.

AIM To compare diffusion tensor image (DTI) study in association fiber tracts among normal control (NC), amnestic mild cognitive impairment (aMCI) and Alzheimers disease (AD) subjects. To assess diagnostic value of DTI in aMCI and differential diagnosis of DTI study between aMCI and AD. MATERIAL AND METHODS DTI was used to assess changes in cerebral association fiber tracts in NC, aMCI, and AD subjects (n = 20/group). Regions of interest included the inferior fronto-occipital fascicles (IFOF), superior longitudinal fascicles and cingulum tract, genu of corpus callosum (Gcc) was set right, splenium of corpus callosum was set left. Bilateral fractional anisotropy (FA) and apparent diffusion coefficient values were compared in three groups. RESULTS Relative to NC, aMCI subjects had significantly different FA values for the IFOF and cingulum tract, while AD subjects had significantly different FA values of IFOF, Gcc, and cingulum tract. Relative to aMCI, AD subjects had significantly different FA values of cingulum tract. CONCLUSION Based on the results, DTI could be used as a diagnostic method for aMCI with abnormal changes in IFOF and cingulum tract. DTI could also be used for differential diagnosis of aMCI and AD by comparing FA values of the cingulum tract. Abnormal FA values of IFOF, Gcc, and cingulum tract in AD patients may help to elucidate the pathological processes in this disease.

Iron Deposition Is Positively Related to Cognitive Impairment in Patients with Chronic Mild Traumatic Brain Injury: Assessment with Susceptibility Weighted Imaging.

Background. This study aimed to evaluate the usability of SWI in assessment of brain iron to detect cognitive dysfunction in patients with chronic mild traumatic brain injury (mTBI). Methods. 39 patients with mTBI and 37 normal controls were given the Mini-Mental State Examination (MMSE) and underwent SWI scanning at least 6 months after injury. Angle radian values were calculated with phase images. The angle radian values were compared between groups using analysis of covariance, and their association with MMSE scores was analyzed using Spearman correlations. Results. Significantly higher angle radian values (p < 0.05) were found in the head of the caudate nucleus, the lenticular nucleus, the hippocampus, the thalamus, the right substantia nigra, the red nucleus, and the splenium of the corpus callosum (SCC) in the mTBI group, compared to the control group. MMSE scores were negatively correlated with angle radian values in the right substantia nigra (r = −0.685, p < 0.001). Conclusions. Patients with chronic mTBI might have abnormally high accumulations of iron, and their MMSE scores are negatively associated with angle radian values in the right substantia nigra, suggesting a role of SWI in the assessment of cognitive impairments of these patients.

Enhanced CT and CT virtual endoscopy in diagnosis of heterotopic pancreas.

AIM To improve the diagnosis of heterotopic pancreas by the use of contrast-enhanced computed tomography (CT) imaging and CT virtual endoscopy (CTVE). METHODS A total of six patients with heterotopic pancreas, as confirmed by clinical pathology and immunohistochemistry in the Sixth Affiliated Peoples Hospital of Shanghai Jiao Tong University, Shanghai, China, were included. Non-enhanced CT and enhanced CT scanning were performed, and the resulting images were reviewed and analyzed using three-dimensional post-processing software, including CTVE. RESULTS Four males and two females were enrolled. Several heterotopic pancreas sites were involved; three occurred in the stomach, including the gastric antrum (n = 2) and lesser curvature (n = 1), and two were in the duodenal bulb. Only one case of heterotopic pancreas lesion occurred in the mesentery. Four cases had a solid yet soft tissue density that had a homogeneous pattern when viewed by enhanced CT. Additionally, their CT values were similar to that of the pancreas. The ducts of the heterotopic pancreas tissue, one of the characteristic CT features of heterotopic pancreas tissue, were detected in the CT images of two patients. CTVE images showed normal mucosa around the tissue, which is also an important indicator of a heterotopic pancreas. However, none of the CTVE images showed the typical signs of central dimpling or umbilication. CONCLUSION CT, enhanced CT and CTVE techniques provide useful information about the location, growth pattern, vascularity, and condition of the gastrointestinal wall around heterotopic pancreatic tissue.