OBJECTIVES: We present a new low-dose CT reconstruction method using sub-pixel and anisotropic diffusion. METHODS: The sub-pixel intensity values and their second-order differences were obtained using linear interpolation techniques, and the new gradient information was then embedded into an anisotropic diffusion process, which was introduced into a penalty-weighted least squares model to reduce the noise in low-dose CT projection data. The high-quality CT image was finally reconstructed using the classical filtered back-projection (FBP) algorithm from the estimated data. RESULTS: In the Shepp-Logan phantom experiments, the structural similarity (SSIM) index of the CT image reconstructed by the proposed algorithm, as compared with FBP, PWLS-Gibbs and PWLS-TV algorithms, was increased by 28.13%, 5.49%, and 0.91%, the feature similarity (FSIM) index was increased by 21.08%, 1.78%, and 1.36%, and the root mean square error (RMSE) was reduced by 69.59%, 18.96%, and 3.90%, respectively. In the digital XCAT phantom experiments, the SSIM index of the CT image reconstructed by the proposed algorithm, as compared with FBP, PWLS-Gibbs and PWLS-TV algorithms, was increased by 14.24%, 1.43% and 7.89%, the FSIM index was increased by 9.61%, 1.78% and 5.66%, and the RMSE was reduced by 26.88%, 9.41% and 18.39%, respectively. In clinical experiments, the SSIM index of the image reconstructed using the proposed algorithm was increased by 19.24%, 15.63% and 3.68%, the FSIM index was increased by 4.30%, 2.92% and 0.43%, and the RMSE was reduced by 44.60%, 36.84% and 15.22% in comparison with FBP, PWLS-Gibbs and PWLS-TV algorithms, respectively. CONCLUSIONS The proposed method can effectively reduce the noises and artifacts while maintaining the structural details in low-dose CT images.
Tomography, X-Ray Computed/methods* ; Algorithms ; Phantoms, Imaging ; Anisotropy ; Image Processing, Computer-Assisted/methods* ; Humans ; Radiation Dosage

This study aimed to define the most consistent white matter microarchitecture pattern in Parkinson's disease (PD) reflected by fractional anisotropy (FA), addressing clinical profiles and methodology-related heterogeneity. Web-based publication databases were searched to conduct a meta-analysis of whole-brain diffusion tensor imaging studies comparing PD with healthy controls (HC) using the anisotropic effect size-signed differential mapping. A total of 808 patients with PD and 760 HC coming from 27 databases were finally included. Subgroup analyses were conducted considering heterogeneity with respect to medication status, disease stage, analysis methods, and the number of diffusion directions in acquisition. Compared with HC, patients with PD had decreased FA in the left middle cerebellar peduncle, corpus callosum (CC), left inferior fronto-occipital fasciculus, and right inferior longitudinal fasciculus. Most of the main results remained unchanged in subgroup meta-analyses of medicated patients, early stage patients, voxel-based analysis, and acquisition with 30 diffusion directions. The subgroup meta-analysis of medication-free patients showed FA decrease in the right olfactory cortex. The cerebellum and CC, associated with typical motor impairment, showed the most consistent FA decreases in PD. Medication status, analysis approaches, and the number of diffusion directions have an important impact on the findings, needing careful evaluation in future meta-analyses.
Anisotropy ; Brain/diagnostic imaging* ; Corpus Callosum ; Diffusion Tensor Imaging ; Humans ; Parkinson Disease/diagnostic imaging* ; White Matter/diagnostic imaging*

To compare the differences in apparent diffusion coefficient (ADC) and fractional anisotropy (FA) between brucella spondylitis (BS) groups at different stages before treatment and the normal control group and to evaluate the change trend of ADC value and FA value at different time points before and after treatment. Totally 53 patients suspected of BS by conventional magnetic resonance imaging (MRI) and later confirmed as BS patients by serological tests were enrolled in this study. These patients underwent conventional MRI and diffusion tensor imaging scans,and the ADC value and FA value were measured. Independent sample test was used to compare the ADC value and FA value between the BS group and the control group,the ADC value and FA value between the BS group at each stage. Repeated measurement ANOV was used to compare the ADC values and FA values at different time points before and after treatment. FA imaging showed that the color code of BS was different from that of the normal control group,and the color code of FA imaging showed increased singal. The ADC values of BS in the acute,subacute,and chronic stages [(1.45±0.02)×10 mm /s,(1.35±0.03)×10 mm /s,(1.26±0.05)×10 mm /s,respectively] were significantly higher than those in the control group [(1.06±0.09) ×10 mm /s](=2.538,=0.009;=1.998,=0.032;=1.575,=0.004),and the FA value (0.55±0.02,0.65±0.03,0.71±0.04,respectively) were significantly lower than those of the control group (0.78±0.02) (=2.440,=0.012; =1.847,=0.041;=2.102,=0.003). Repeated measurement analysis showed that there were statistically significant differences in ADC values and FA values at different time points before and after treatment in the acute,subacute,and chronic stages (ADC:=12.100,<0.001;=8.439,=0.005;=9.704,=0.004,respectively;FA:=7.080,=0.002;=6.607;=0.003;=8.868,=0.001,respectively). The ADC values at different time points after treatment were significantly lower than those before treatment or at a previous time point after treatment (=332.14,<0.001),and the FA values were significantly higher than those before treatment or at a previous time point after treatment (=134.26,<0.001). FA color code can intuitively display differences in BS and normal vertebral bodies and show change of color code before and after treatment. Also,the ADC values and FA values can quantitatively reveal differences between BS and normal vertebral body in different time points and quantify BS vertebral lesion changes before and after treatment. In particular,in BS patients who are recovering from treatment,it can quantify microscopic edema. Therefore,diffusion tensor imaging may be useful objective indicator in evaluating the effectiveness of a specific treatment for BS.
Anisotropy ; Brucella ; Brucellosis ; diagnostic imaging ; Diffusion Magnetic Resonance Imaging ; Diffusion Tensor Imaging ; Humans ; Spondylitis ; diagnostic imaging ; microbiology

OBJECTIVE: We aimed to investigate the ability of readout-segmented echo-planar imaging (rs-EPI)-based diffusion tensor imaging (DTI) in assessing the microstructural change of extraocular muscles (EOMs) and optic nerves in patients with thyroid-associated orbitopathy (TAO) as well as in evaluating disease activity.MATERIALS AND METHODS: We enrolled 35 TAO patients and 22 healthy controls (HCs) who underwent pre-treatment rs-EPI-based DTI. Mean, axial, and radial diffusivity (MD, AD, and RD) and fractional anisotropy (FA) of the medial and lateral EOMs and optic nerve for each orbit were calculated and compared between TAO and HC groups and between active and inactive TAO groups. Factors such as age, sex, disease duration, mediation, and smoking history between groups were also compared. Logistic regression analysis was used to evaluate the predictive value of significant variables for disease activity.RESULTS: Disease duration was significantly shorter in active TAOs than in inactive ones (p < 0.001). TAO patients showed significantly lower FA and higher MD, AD, and RD than HCs for both medial and lateral EOMs (p < 0.001), but not the AD value of lateral EOMs (p = 0.619). Active patients had significantly higher FA, MD, and AD than inactive patients for medial EOMs (p < 0.005), whereas only FA differed significantly in the lateral EOMs (p = 0.018). The MD, AD, and RD of optic nerves were significantly lower in TAO patients than HCs (p < 0.05), except for FA (p = 0.129). Multivariate analysis showed that the MD of medial EOMs and disease duration were significant predictors for disease activity. The combination of these two parameters showed optimal diagnostic efficiency for disease activity (area under the curve, 0.855; sensitivity, 68.4%; specificity, 96.9%).CONCLUSION: rs-EPI-based DTI is promising in assessing microstructural changes of EOMs and optic nerves and can help to indicate the disease activity of TAO, especially through the MD of medial EOMs.
Anisotropy ; Diffusion Tensor Imaging ; Diffusion ; Echo-Planar Imaging ; Humans ; Logistic Models ; Multivariate Analysis ; Muscles ; Negotiating ; Optic Nerve ; Orbit ; Sensitivity and Specificity ; Smoke ; Smoking ; Troleandomycin

OBJECTIVE: To study the value of fractional anisotropy (FA) of regions of interest (ROI) on magnetic resonance diffusion tensor imaging (DTI) in bilirubin-induced neurological dysfunction in neonates. METHODS: A total of 91 neonates with hyperbilirubinemia who were hospitalized from January 2017 to January 2018 were enrolled. According to the peak level of total serum bilirubin, they were divided into three groups: mild/moderate increase (n=45), severe increase (n=35), and extremely severe increase (n=11). According to the presence or absence of abnormal neurological manifestations, they were divided into two groups: neurological dysfunction (n=20) and non-neurological dysfunction (n=71). Ten healthy full-term infants were enrolled as the control group. Head DTI was performed for all neonates to measure the FA values of the bilateral globus pallidus, the anterior limb of the internal capsule, the posterior limb of the internal capsule, and the cerebellar dentate nucleus. RESULTS: The extremely severe increase group had significantly lower FA values of the globus pallidus than the control, mild/moderate increase, and severe increase groups (P<0.05). The severe increase group had significantly lower FA values of the globus pallidus than the control group (P<0.05). The extremely severe increase group had significantly lower FA values of the posterior limb of the internal capsule than the control, mild/moderate increase, and severe increase groups (P<0.05). The neurological dysfunction group had significantly lower FA values of the globus pallidus and the posterior limb of the internal capsule than the non-neurological dysfunction group (P<0.05). CONCLUSIONS Serum bilirubin level combined with the changes in the DTI FA values of the globus pallidus and the posterior limb of the internal capsule can be used to predict the injury of cerebral nuclei and white matter fibers.
Anisotropy ; Bilirubin ; Brain ; Diffusion Magnetic Resonance Imaging ; Diffusion Tensor Imaging ; Humans ; Infant, Newborn ; Magnetic Resonance Imaging ; Magnetic Resonance Spectroscopy ; White Matter

BACKGROUND AND PURPOSE: There is accumulating evidence that epilepsy is caused by network dysfunction. We evaluated the hub reorganization of subcortical structures in patients with focal epilepsy using graph theoretical analysis based on diffusion-tensor imaging (DTI). In addition, we investigated differences in the values of diffusion tensors and scalars, fractional anisotropy (FA), and mean diffusivity (MD) of subcortical structures between patients with focal epilepsy and healthy subjects. METHODS: One hundred patients with focal epilepsy and normal magnetic resonance imaging (MRI) findings and 80 age- and sex-matched healthy subjects were recruited prospectively. All subjects underwent DTI to obtain data suitable for graph theoretical analysis. We investigated the differences in the node strength, cluster coefficient, eigenvector centrality, page-rank centrality measures, FA, and MD of subcortical structures between patients with epilepsy and healthy subjects. RESULTS: After performing multiple corrections, the cluster coefficient and the eigenvector centrality of the globus pallidus were higher in patients with epilepsy than in healthy subjects (p=0.006 and p=0.008, respectively). In addition, the strength and the page-rank centrality of the globus pallidus tended to be higher in patients with epilepsy than in healthy subjects (p=0.092 and p=0.032, respectively). The cluster coefficient of the putamen was lower in patients with epilepsy than in healthy subjects (p=0.004). The FA values of the caudate nucleus and thalamus were significantly lower in patients with epilepsy than in healthy subjects (p=0.009 and p=0.007, respectively), whereas the MD value of the thalamus was higher than that in healthy subjects (p=0.005). CONCLUSIONS: We discovered the presence of hub reorganization of subcortical structures in focal epilepsy patients with normal MRI findings, suggesting that subcortical structures play a pivotal role as a hub in the epilepsy network. These findings further reinforce the idea that epilepsy is a network disease.
Anisotropy ; Caudate Nucleus ; Connectome ; Diffusion ; Epilepsies, Partial* ; Epilepsy ; Globus Pallidus ; Healthy Volunteers ; Humans ; Magnetic Resonance Imaging ; Prospective Studies ; Putamen ; Thalamus

BACKGROUND: We utilized diffusion tensor imaging (DTI) to evaluate the cerebral white matter changes that are associated with phantom limb pain in patients with unilateral arm amputation. It was anticipated that this would complement previous research in which we had shown that changes in cerebral blood volume were associated with the cerebral pain network. METHODS: Ten patients with phantom limb pain due to unilateral arm amputation and sixteen healthy age-matched controls were enrolled. The intensity of phantom limb pain was measured by the visual analogue scale (VAS) and depressive mood was assessed by the Hamilton depression rating scale. Diffusion tensor-derived parameters, including fractional anisotropy, mean diffusivity, axial diffusivity (AD), and radial diffusivity (RD), were computed from the DTI. RESULTS: Compared with controls, the cases had alterations in the cerebral white matter as a consequence of phantom limb pain, manifesting a higher AD of white matter in both hemispheres symmetrically after adjusting for individual depressive moods. In addition, there were associations between the RD of white matter and VAS scores primarily in the hemispheres related to the missing hand and in the corpus callosum. CONCLUSIONS: The phantom limb pain after unilateral arm amputation induced plasticity in the white matter. We conclude that loss of white matter integrity, particularly in the hemisphere connected with the missing hand, is significantly correlated with phantom limb pain.
Amputation ; Anisotropy ; Arm ; Blood Volume ; Brain ; Chronic Pain ; Complement System Proteins ; Corpus Callosum ; Depression ; Diffusion ; Diffusion Tensor Imaging ; Hand ; Humans ; Magnetic Resonance Imaging ; Neuronal Plasticity ; Phantom Limb ; Plastics ; White Matter

STUDY DESIGN: Observational comparative study. PURPOSE: To compare fractional anisotropy (FA) maps with T2 values of the nucleus pulposus (NP) and annulus fibrosus (AF) of intervertebral discs in healthy volunteers and patients to develop a predictive disc health scale. OVERVIEW OF LITERATURE: T2-weighted magnetic resonance imaging (MRI) is not sensitive to early morphological changes and provides no quantitative biomarker profile for early degeneration. METHODS: We examined 59 healthy controls and 59 patients with back pain by MRI using T2 relaxometry and diffusion tensor imaging (DTI). Each group was divided into three age subgroups: A (<30 years, n=12); B (30–50 years, n=26); and C (>50 years, n=21). We obtained FA values for AF and NP and T2 values for NP for each intervertebral disc. Furthermore, we calculated the FA (AF/NP) ratios. RESULTS: We categorized 590 intervertebral discs from 118 participants, 566 of which were analyzed with T2 relaxometry and DTI. The T2 values were as follows: subgroup A, 55.8±4.4 ms; B, 48.5±6.9 ms; C, 45.8±8.7 ms (p<0.050). The T2 values for the healthy controls of the subgroups A, B, and C were >120 ms, 90–100 ms, and 70 ms, respectively (p<0.001). Control subgroup A had higher T2 values and AF/NP ratios than subgroups B and C; the AF values were not significantly different. Control subgroup B had higher T2 values and AF/NP ratios than subgroup C but lower FA (NP). CONCLUSIONS: FA maps of the AF/NP ratio and T2 values of NP are potential microstructure biomarkers of normal and degenerating discs and can help detect early degeneration using a predictive disc health score on a continuous scale.
Anisotropy ; Back Pain ; Biomarkers ; Diffusion Tensor Imaging ; Healthy Volunteers ; Humans ; Intervertebral Disc Degeneration ; Intervertebral Disc ; Magnetic Resonance Imaging

BACKGROUND AND PURPOSE: Benign epilepsy with centrotemporal spikes (BECTS) is one of the most common pediatric epilepsies, and it generally has a good prognosis. However, recent research has indicated that the epileptic activity of BECTS can cause cognitive defects such as language, visuospatial, and auditory verbal memory deficits. This study assessed language-delivery deficits in BECTS patients using diffusion-tensor magnetic resonance imaging (DTI). METHODS: T1-weighted MRI, DTI, and language tests were conducted in 16 BECTS patients and 16 age-matched controls. DTI data were analyzed using the TRActs Constrained by Underlying Anatomy tool in FreeSurfer 5.3, and 18 major white-matter tracts were extracted, which included 4 language-related tracts: the inferior longitudinal fasciculus, superior longitudinal fasciculus-parietal terminations, superior longitudinal fasciculus-temporal terminations, and uncinate fasciculus (UNC). Language tests included the Korean version of the Receptive and Expressive Vocabulary Test, Test of Problem-Solving Abilities (TOPS), and the mean length of utterance in words. RESULTS: The BECTS group exhibited decreased mean fractional anisotropy and increased mean radial diffusivity, with significant differences in both the superior longitudinal fasciculus and the left UNC (p<0.05), which are the language-related white-matter tracts in the dual-loop model. The TOPS language test scores were significantly lower in the BECTS group than in the control group (p<0.05). CONCLUSIONS: It appears that BECTS patients can exhibit language deficits. Seizure activities of BECTS could alter DTI scalar values in the language-related white-matter tracts.
Anisotropy ; Child ; Cognition Disorders ; Epilepsy ; Epilepsy, Rolandic ; Humans ; Language Tests ; Magnetic Resonance Imaging ; Memory Disorders ; Prognosis ; Retrospective Studies ; Seizures

OBJECTIVES: To compare the white matter microstructure of dyslexic children with normal children using diffusion tensor imaging. METHODS: Twenty one dyslexic children and 24 normal control children were recruited in the second and third grade of elementary school students. The fractional anisotropy (FA) values of 20 representative white matter tracts were estimated from the diffusion tensor imaging data of each subject using the Johns Hopkins University-white matter tractography atlas to determine the difference in white matter integrity between the dyslexic children and normal children. RESULTS: Compared to the normal control group, the FA values of the left inferior longitudinal fasciculus [F(1,39)=5.908, p<0.05] and temporal part of the right superior longitudinal fasciculus [F(1,39)=7.328, p=0.010] were significantly higher in the dyslexic group and there was no significant difference in the other tracts. CONCLUSION: In dyslexic children, compensatory pathways develop in the left inferior longitudinal fasciculus and in the temporal part of the right superior longitudinal fasciculus.
Anisotropy ; Case-Control Studies ; Child ; Diffusion Tensor Imaging ; Dyslexia ; Humans ; White Matter