Optimizing Fractional Intensity Threshold for FSLBrain Extraction Tool (BET) and Comparing with FreeSurfer on 3D T1W MR Images

Objective: To find out the optimal Brain Extraction Tool (BET) parameter (fractional intensity threshold) for measuring the brain volume compared with the standard manual method in our institute and to compare with those of automated FreeSurfer software Methods: This retrospective study was performed in 10 healthy adult subjects with data of 3D-T1W on 3T MR machine. The manual gold standard brain volume measurements were done by two independent readers. The automated segmentation using BET with varied parameters and FreeSurfer software were also performed. Then, the two automated methods were compared with the manual tracing to make the optimal parameter by seeking the highest intraclass correlation coefficient (ICC) using SPSS software. Results: The fractional intensity threshold for whole brain volume measurement of 0.1- 0.6 showed high ICC with the manual gold standard (ranging from 0.639 to 0.748). The best value was 0.1, showing highest ICC of 0.748 (p < 0.006) with confidence interval of 95% equal to (0.242; 0.932). There were no optimal parameters for right and left hippocampus volume measurement by BET due to very low ICC between BET and the reader (ICC ranging from 0.017 to 0.139 and from 0.012 to 0.110, for the right and left hippocampus volume, respectively). The ICC values of the automated FreeSurfer method with the manual tracing were also very low (0.063, 0.068, and 0.063 for right, left and bilateral hippocampi respectively). Conclusion: The optimal BET parameter (fractional intensity threshold) for automated brain volume measurement in our institute is 0.1 similar to the suggested value by prior study with high agreement (ICC=0.748) to the manual method

The Evaluation of Posterior Cingulate Gyrus by Diffusion Tensor Imaging in Alzheimer’s Disease Patients Compared with Normal Control Subjects

Objective: Posterior cingulate gyrus atrophy is found in early clinical stage of Alzheimer’s disease (AD) patients.1 Diffusion tensor imaging (DTI) can be used for evaluating microstructure change in brain parenchyma.2 Our objective was to compare the microstructural change at posterior cingulate gyrus between AD patients and normal control subjects by using DTI. Methods: The retrospective review of 23 AD patients, diagnosed by NINCDS-ADRDA with available MRI data including DTI, and 19 normal control subjects was performed. The DTI parameters of posterior cingulate gyrus of each group were analyzed and compared. Results: The mean diffusivity (MD), axial diffusivity and radial diffusivity (RD) of posterior cingulate gyrus were significantly increased in AD patients compared with normal control subjects (p value <0.001, <0.001, <0.001, respectively). The fractional anisotropy (FA) was slightly decreased in AD patients compared with normal control subjects but did not reach statistical significance (p value=0.71). Conclusion: Microstructural change at posterior cingulate gyrus demonstrated by DTI parameters including MD, axial diffusivity and RD were significantly different between AD patients and normal control subjects. These results were probably helpful for early diagnosis, evaluation, and follow up of the AD patients as correlate with clinical findings

The Evaluation of Posterior Cingulate Gyrus by Diffusion Tensor Imaging in Alzheimer’s Disease Patients Compared with Normal Control Subjects

Objective: Posterior cingulate gyrus atrophy is found in early clinical stage of Alzheimer’s disease (AD) patients.1 Diffusion tensor imaging (DTI) can be used for evaluating microstructure change in brain parenchyma.2 Our objective was to compare the microstructural change at posterior cingulate gyrus between AD patients and normal control subjects by using DTI. Methods: The retrospective review of 23 AD patients, diagnosed by NINCDS-ADRDA with available MRI data including DTI, and 19 normal control subjects was performed. The DTI parameters of posterior cingulate gyrus of each group were analyzed and compared. Results: The mean diffusivity (MD), axial diffusivity and radial diffusivity (RD) of posterior cingulate gyrus were significantly increased in AD patients compared with normal control subjects (p-value <0.001, <0.001, <0.001, respectively). The fractional anisotropy (FA) was slightly decreased in AD patients compared with normal control subjects but did not reach statistical significance (p value=0.71). Conclusion: Microstructural change at posterior cingulate gyrus demonstrated by DTI parameters including MD, axial diffusivity and RD were significantly different between AD patients and normal control subjects. These results were probably helpful for early diagnosis, evaluation, and follow up of the AD patients as correlate with clinical findings

Clinical improvements in temporospatial gait variables after a spinal tap test in individuals with idiopathic normal pressure hydrocephalus

Background: Idiopathic Normal Pressure Hydrocephalus (iNPH) is a neurological condition that often presents gait disturbance in the early stages of the disease and affects other motor activities. This study investigated changes in temporospatial gait variables after cerebrospinal fluid (CSF) removal using a tap test in individuals with idiopathic normal pressure hydrocephalus (iNPH), and explored if the tap test responders and non-responders could be clinically identified from temporospatial gait variables. Methods: Sixty-two individuals with iNPH were recruited from an outpatient clinic, eleven were excluded, leaving a total of 51 who were included in the analysis. Temporospatial gait variables at self-selected speed were recorded at pre- and 24-hour post-tap tests which were compared using Paired t-tests, Cohen’s d effect size, and percentage change. A previously defined minimal clinical important change (MCIC) for gait speed was used to determine the changes and to classify tap test responders and non-responders. A mixed model ANOVA was used to determine the within-group, between-group, and interaction effects. Results: Comparisons of the data between pre- and post-tap tests showed significant improvements with small to medium effect sizes for left step length, right step time, stride length and time, cadence, and gait speed. Gait speed showed the largest percentage change among temporospatial gait variables. Within-group and interaction effects were found in some variables but no between-group effect was found. Tap test responders showed significant improvements in right step length and time, stride length and time, cadence, and gait speed while non-responders did not. Conclusions: Some individuals with iNPH showed clinically important improvements in temporospatial gait variables after the tap test, particularly in step/stride length and time, cadence, who could be classified by gait speed. However, gait-related balance variables did not change. Therefore, additional treatments should focus on improving such variables

Diffusion Tensor Imaging in Idiopathic Normal Pressure Hydrocephalus: Evaluation Between Shunt Responsive and Shunt Non-Responsive Groups in Siriraj Hospital

Objective: Patient evaluation for the treatment of idiopathic normal pressure hydrocephalus (iNPH) with noninvasive investigation is helpful. Diffusion tensor imaging (DTI) can evaluate the microstructural change in brain parenchyma. The aim of this study was to compare diffusion tensor parameters in the brain before treatment in shunt responsive and shunt non-responsive iNPH patient groups to identify any difference between groups. Methods: Total 16 subjects with iNPH, 13 overall shunt responsive patients, and three overall shunt non-responsive patients were recruited and underwent MRI study (3-Tesla), including DTI with 32 gradient directions. Patients were scanned before cerebrospinal fluid tap test (CSF-TT) and shunt surgery. Fractional anisotropy (FA) and apparent diffusion coefficient (ADC) between 2 groups were assessed by manual region of interest (ROI) method with FA color support. DTI parameters were correlated with the surgical outcome by clinical assessment. Results: No statistically significant difference between overall outcome with FA and ADC in all ROIs was found. However, among the overall shunt responsive group, FA was higher, and ADC was lower than the overall shunt non-responsive group in almost all ROIs, except splenium of the corpus callosum (SPL). The difference was seen predominately at the body of the corpus callosum (CCbo) and genu of corpus callosum (GENU), but less at corticospinal tract pathway (CST), including corona radiata, posterior limb of internal capsule, and corticospinal tract at pons level (CR, PLIC, and Po). Subgroup analysis also showed the same tendency in the gait shunt responsive group, urinary symptom shunt responsive group, and cognitive shunt responsive group. Conclusion: DTI can investigate white matter microstructural change in the iNPH patient. The overall shunt responsive group tends to have higher FA and lower ADC than the overall shunt non-responsive group in almost all ROIs, except SPL. However, no statistically significant difference was found. Further study and comparison between pre and post shunt placement surgery in iNPH patients will be helpful

Comparison between Dynamic Contrast-Enhanced MRI and Dynamic Susceptibility Contrast MRI in Glioma Grading

Objective: To determine the usefulness of the dynamic contrast-enhanced MRI (DCE-MRI) technique for differentiating between low-grade glioma and high-grade glioma and compare with dynamic susceptibility contrast (DSC) MRI. Methods: Conventional MRI, DCE-MRI, and DSC-MRI were performed preoperatively in 17 patients with gliomas. Permeability indices (Ktrans, rKtrans, Ve, and Kep) from DCE-MRI and cerebral blood volume (CBV), rCBV from DSCMRI were quantified. The differences in Ktrans, rKtrans, Ve, Kep, CBV and rCBV between low-grade glioma and high-grade glioma were analyzed and compared. Receiver operating characteristic (ROC) curve analyses were conducted. Results: Ktrans, rKtrans, Ve, CBV and rCBV were significantly different between low grade glioma and high grade glioma (p = 0.001, 0.014, 0.02, 0.025, and 0.034, respectively). The areas under the ROC curve for Ktrans, rKtrans, Ve, rCBV and CBV were 0.986, 0.896, 0.829, 0.852, and 0.833, respectively. Ktrans was the best parameter for differentiating low grade glioma from high grade glioma with cutoff value of 0.0091 min-1 (sensitivity 100%, specificity 80%, PPV 87.5%, NPV 100%, accuracy 94.1%). Conclusion: DCE-MRI could be used to estimate neovascular permeability and for pre-operative grading of glioma. Among the perfusion parameters, Ktrans was the best parameter for differentiating low grade glioma from high grade glioma . DCE-MRI may be promising for better diagnostic performance than DSC-MRI