Voxel Research Articles

Pseudo-CT Generation from Magnetic Resonance Imaging by fuzzy look up table algorithm

Introduction: Despite growing interest in the use of magnetic resonance imaging (MRI) in the external radiotherapy design process (RT), Computer Tomography (CT) remains a gold standard and is regarded as a basic imaging modality in radiotherapy. MRI shows the high contrast in soft tissues without any radiation exposure to patients. As a result, MRI is used in functional tissue structures with registration on the CT images. Unfortunately, this causes systematic errors during the registration of MRI and CT images. The purpose of this study is to investigate the possibility of removing the CT simulator images and replacing it with pseudo-CT images (which created by MRI images) for the electron density calculation in radiotherapy treatment planning. Materials and Methods: The pseudo-CT images were generated for 10 randomly chosen patients with brain disease. Data consisted of image voxels chosen within the segmented area of the brain in both MRI and CT images. The relation between MRI intensity and electron density was derived from HU converted model by fuzzy look up table algorithm. Results: It was found that the MRI intensity value is related to the HU value within different parts such as skull bone, sinus, and brain. The mean prediction errors of the conversion model are -0.53, -0.082, 0.0145HU in brain, skull and air regions respectively. The mean absolute errors are 19.40 , 50.53,1.22 Conclusion: The proposed method enables generation of pseudo-CT data for the different segmented part of the brain from MRI series with appropriate mean prediction errors.

Quantification and construction of the effective point calculation model of ionization chamber in Monacao treatment planning system

Objective Because of statistical noise in Monte Carlo dose calculations, the effective point doses may not be accurately calculated. A user-defined sphere volume was adopted to substitute the effective point to take sphere sampling around the effective point, which minimize the random errors and improve the accuracy of statistical dose. Methods Direct dose measurements were performed at 0°and 90°using a 0.125 cm3 Semiflex ionization chamber (IC) 31010 isocentrically placed in the center of a homogeneous Cylindric sliced RW3 phantom (PTW, Germany). In the scanned CT phantom series, the sensitive volume length of the IC (6.5 mm) was delineated and the isocenter was defined as the simulated effective point. All beams were simulated in the treatment planning system (TPS) in accordance to the measured model. The grid spacing was calculated by 2 mm voxels and the relative standard deviation should be ≤0.5%.The statistical and measured doses were statistically compared among three IC models with different electron densities (ED; esophageal lumen ED=0.210 g/cm3 for model A, air ED=0.001 g/cm3 for model B and the default CT scanned ED for model C) at different sampling sphere radius (2.5, 2.0, 1.5 and 1.0 mm) to evaluate the effect of Monte Carlo.calculation uncertainty upon the dose accuracy. Results In the Monaco TPS, the statistical value was in the highest accordance with the measured value with an absolute average deviation of 0.49% when the IC was set as esophageal lumen ED=0.210 g/cm3 and the sampling sphere radius was 1.5 mm. When the IC was set as air ED=0.001 g/cm3 and default CT scanned ED, and, the recommended statistical sampling sphere radius was 2.5 mm, the absolute average deviations were 0.61% and 0.70%. Conclusion In the Monaco TPS, the calculation model with an ED of 0.210 g/cm3 and a sampling radius of 1.5 mm is recommended for the ionization chamber 31010 to substitute the effective point dose measurement to decrease the random stochastic errors of Monte Carlo. Key words: Monte Carlo; Ionization chamber model; Treatment planning system; Sphere sampling

Correction to: Precise and economic FIB/SEM for CLEM: with 2nm voxels through mitosis.

Unfortunately, part of the legend to Fig.6 has been incorrectly published.

Volumetric FDG PET analysis of global lung inflammation: new tool for precision medicine in pulmonary sarcoidosis?

Currently FDG PET/CT is used as a tool for detection of active sites of sarcoidosis. Routine clinical practice relies on qualitative assessment with visual interpretation. When semi quantitatively expressed, e.g. for scientific purposes, this often leads to dichotomous "positive" or "negative" results. Metabolic activity in the lungs or mediastinum can also be expressed by SUVmax, but this measure is based only on the intensity of a single voxel. Likely for this reason these parameters show poor correlation with variables such as serum biomarkers and suboptimally predict clinical response to treatment. The current study focusses on new volumetric quantification methods for FDG PET/CT. Specifically the percentage of lung volume with increased metabolic activity, "%SUV-high", and the average metabolic activity in the lung "SUVmean", shows significantly better correlation with conventional biomarkers for disease activity than PET dichotomous and SUVmax. Our proposed quantification method needs subsequent and larger studies, however it may open new possibilities for future quantitative research in lung inflammation, and improve precision medicine in sarcoidosis. (Sarcoidosis Vasc Diffuse Lung Dis 2018; 35: 44-54).

Reliability of functional connectivity in resting-state functional MRI

Functional MRI is a noninvasive method in brain imaging. Localization, classification, prediction and connectivity are the most common issues. Functional connectivity is a branch of fMRI that focuses on connectivity between voxels and ROIs. There are several methods for investigating functional connectivity such as correlation analysis. In any field, it is very important that results of any research have reliability according to the experiment. Any methods and measurement instruments need to be reliable. Without reliability, results are meaningless and our research is not trustworthy. Brain imaging can be used as a valuable tool for pre-surgical planning, so the results should be highly reproducible. Test-retest reliability can be explored using the intra-class correlation coefficient (ICC). I2C2 is an extent of ICC to verify the reliability in high-dimensional data as imaging studies. 13 subjects of test-retest resting-state fMRI are used to investigate reliability. I2C2 of four ROIs are also computed (Caudate, Cingulate, Cuneus and Precentral regions). Functional connectivity is found to have moderate reliability ranging 0.6244 to 0.6941. 95% confidence interval of I2C2 is calculated by nonparametric bootstrap in which CI of Caudate region I2C2 has the shortest length.

Apolipoprotein E polymorphism affects brain functional connectivity density in healthy young adults: a resting-state functional MRI

Objective To explore the aberrance of brain activity in healthy young adults with apolipoprotein E (APOE) e2, e3 and e4 allele by the method of functional connectivity density (FCD) . Method Two hundred and thirteen young healthy adults underwent the 3 T resting-state functional MRI, the neuropsychological tests and genotype testing for e2, e3 and e4 allele. Age -and gender-matched individuals, including 14 subjects with APOE e2, 31 subjects with APOE e4 and 31 subjects with APOE e3 were enrolled for final analysis. FCD mapping was used to compare the brain functional connective networks among the three groups. All results were corrected with a Gaussian random field (GRF) (voxel-level of P<0.01 and joint cluster-level of P<0.05) . Correlation analysis was performed between abnormal short -and long-range FCD values and neuropsychological scores. Results Compared with APOE e3 carriers, the short -and long-range FCD values of APOE e2 carriers were increased in the frontal lobe, particularly in the medial prefrontal lobe (37 voxels, t=3.54) , anterior cingulate cortex (36 voxels, t=3.19) and orbital frontal cortex (41 voxels, t=3.72) , while APOE e4 carriers showed decreased short-range FCD in the bilateral cuneus (38 voxels, t=-3.68) . Moreover, the long-range FCD values of APOE e4 group were decreased in right orbital frontal cortex (46 voxels, t=-4.56) and increased in the right inferior parietal lobe (31 voxels, t=3.49) compared with that of APOE e2 group. No significant correlation was detected with Bonferroni correction. Conclusions The opposite FCD alteration in cuneus and inferior parietal lobe might be the early existence of inhibitory and compensatory mechanism modulated by the e4 allele in the young age, while the increased FCD in frontal lobe might be the underlying protective mechanism of delaying the onset of Alzheimer's disease. Key words: APOE polymorphism; Functional connectivity density; Alzheimer disease

In Vivo 1H Magnetic Resonance Spectroscopy.

In vivo Magnetic Resonance Spectroscopy (MRS) allows the non-invasive detection and quantification of a number of metabolites from localized volumes within a living organism. MRS localization techniques can be divided into two main groups, single voxel and multi-voxel. Single voxel techniques provide the metabolic profile from a specific small volume, whereas multi-voxel techniques are used to obtain the spatial distribution of metabolites throughout a large volume subdivided into small contiguous voxels. This chapter describes standard protocols for the acquisition and processing of in vivo single voxel1H MRS data from the rodent brain.

改进的体素生长算法在心脏局部血管提取中的应用

改进的体素生长算法在心脏局部血管提取中的应用

Application of arterial spin labeling in pediatric brain diseases

Arterial spin labeling (ASL), unlike dynamic magnetic susceptibility contrast enhanced perfusion imaging, does not require contrast agents and it is a reusable and noninvasive imaging approach.This technique reverses the marker flow to the arterial blood protons of the brain and then uses its tracer to evaluate brain perfusion.If all labeled blood arrive at the imaging voxel at the time of image acquisition, the signal difference between the marker image and the control image will be proportional to the cerebral blood flow.In recent years, with the development of ASL technology, pediatric brain diseases such as ischemia and hypoxic encephalopathy, pediatric epilepsy, pediatric encephalitis and other diagnosis has made new progress. Key words: Arterial spin labeling; Hypoxic-ischemic encephalopathy; Epilepsy; Encephalitis; Child; Magne-tic resonance imaging

A resting-state functional MRI study on brain control of bladder storage function

Objective In order to observe central responses during naturally occurring urinary bladder storage in healthy subjects, we examined brain areas that control strong bladder sensation by resting-state functional magnetic resonance imaging (rs-fMRI). Methods 44 healthy subjects (19 men and 25 women, between 22 and 50 years of age) were screened in the study from October 2014 to October 2016. All subjects were right-handed and scanned twice under the following two conditions: empty bladder(bladder volume <10 ml)and full bladder ('strong desire to void’, bladder volume between 200 and 400 ml) without the use of filling with a catheter. Brain imaging softwares (SPM8, DPABI, REST) were adopted to analyze the difference in brain-blood perfusion between these two conditions. Voxel-based analysis of the regional homogeneity (ReHo) was performed to analyze rs-fMRI data including the main excitatory regions and inhibitory areas, peak value (X-axis, Y-axis, Z-axis), clusters size(active volume unit: number of voxel), T value (the excitatory and inhibitory extent of brain active regions). Results The rs-fMRI scans of 44 healthy subjects were analyzed. Nine subjects were excluded because of excessive head movements of more than 1.5 mm and 1.5° in rotation. Data sets were obtained from 35 subjects in two states of bladder, empty bladder and strong desires to void. Increased activity during strong desire to void was observed in the prefrontal cortex (PFC), anterior cingulate cortex (ACC), hypothalamus, temporal lobes and left caudate nucleus. Conclusions There are significant changes in the brain’s ReHo during the strong sensation to void. The results suggest that the PFC, the ACC, hypothalamus, temporal lobes and left caudate nucleus play a role in the cerebral control of bladder storage without artificial bladder filling in healthy people. Key words: Urinary bladder; Brain control; Urge; Storage function; Resting-state functional MRI

Role of magnetic resonance diffusion tensor imaging on prognostic evaluation of term neonates with asphyxia

Objective To discuss the prognostic evaluation of magnetic resonance diffusion tensor imaging (DTI)in term neonates with mild and severe asphyxia. Methods Eleven neonates with mild asphyxia, 14 neonates with severe asphyxia and 10 control neonates were studied.All the neonates were examined by conventional magnetic resonance imaging(MRI) and DTI.Fraction anisotropy (FA) values, apparent diffusion coefficient (ADC) values, voxel numbers and fiber numbers were calculated in seven regions of interest(ROI) and compared among the 3 groups.The correlation between FA values and neonatal behavioral neurological assessment(NBNA)scores were analyzed. Results (1) FA values in the left and the right thalamus were 0.54±0.08 and 0.56±0.15 in control group, 0.45±0.03 and 0.44±0.10 in mild group, and 0.21±0.11 and 0.25±0.13, respectively in severe group .FA values in posterior limbs of internal capsule were 0.49±0.09 and 0.48±0.08 in control group, 0.37±0.08 and 0.38±0.03 in mild group, and 0.20±0.04, 0.19±0.13 in severe group; FA values in thalamus and posterior limbs of internal capsule had statistical differences among the 3 groups(F=9.12, 9.11, 8.18, 8.55, all P<0.05). Voxel numbers in the left and the right superior longitudinal fasciculus were 1 094±112 and 1 123±113 in control group, 986±111 and 1 009±144 in mild group, 450±116 and 671±126 in severe group.Voxel numbers in anterior limbs of internal capsule were 947±104 and 1 237±184 in control group, 854±118 and 799±114 in mild group, 324±110 and 311±126 in severe group.Voxel numbers in posterior limbs of internal capsule were 2 047±129 and 2 137±238 in control group, 1 843±233 and 1 753±247 in mild group, 867±118 and 999±167 in severe group.Voxel numbers in superior longitudinal fasciculus, anterior and posterior limbs of internal capsule had statistical differences among the 3 groups(F=10.11, 9.45, 7.33, 8.45, 12.65, 11.23, all P<0.05); Fiber numbers in the left and the right cingulate gyrus were 245±72 and 405±94 in control group, 225±52 and 365±114 in mild group, 145±62 and 185±84 in severe group.Fiber numbers in inferior front-occipital fasciculus were 56±19 and 212±33 in control group, 49±22 and 197±33 in mild group , 33±12 and 156±39 in severe group.Fiber numbers in posterior limbs of internal capsule were 284±112 and 988±233 in control group, 234±67 and 678±234 in mild group, 114±67 and 188±84 in severe group.Fiber numbers in cingulate gyrus, inferior front-occipital fasciculus and posterior limbs of internal capsule had statistical differences among the 3 groups (F=3.11, 3.45, 9.88, 9.12, 7.45, 8.88, all P<0.05). (2)The correlation between FA value and NBNA scores was analyzed: the correlation coefficient in posterior limbs of internal capsule was 0.666 which was higher than those of the other areas.The area under the ROC curve of FA values in anterior limbs of internal capsule was 0.816 (P=0.005), used NBNA scores≥35 as a good outcome.FA values (≥0.375) in the posterior limbs of the internal capsules predicted a good outcome and the corresponding sensitivity and specificity was 73.1% and 77.8%, respectively. Conclusion In some ROIs, FA values, voxel numbers, and fiber numbers can quantitatively reflect the degree of white matter injury in neonates with asphyxia.Furthermore, the FA values in the posterior limbs of the internal capsules are closely correlated with NBNA scores, so it has more important clinical significance, and can accurately and objectively assess the prognosis in neonates with asphyxia. Key words: Infant, newborn; Asphyxia; Diffusion tensor imaging; Fraction anisotropy; White matter fiber tractography

The absolute quantitative analysis of cingulate cortex metabolites in preschool children with autism spectrum disorder using proton MR spectroscopy

Objective To investigate the metabolite changes in the preschool children with autism spectrum disorder (ASD) using MR spectroscopy (MRS) and explore the associations between image findings and clinical variables, which may provide a noninvasive brain biochemical method for the early diagnosis and prevention of autism. Methods Twenty one cases of preschool ASD children (3-6 years old) and age-and sex-matched 20 preschool healthy controls underwent single voxel short (SVS) short TE (TE=30 ms) MRS. The absolute metabolite concentrations in the anterior cingulate cortex (ACC), anterior middle anterior cingulate cortex (aMCC) and posterior cingulate (PCC) were quantitatively analyzed using LCModel software. Two independent sample t tests were used for analysis. The relationships between metabolite concentrations and diagnostic and statistical manual of mental disorders (DSM-IV), childhood autism rating scale (CARS) and autism behavior checklist (ABC) were analyzed by Pearson correlation analysis. Results Compared to control subjects, ASD patients had significantly lower N-acetylaspartate (NAA) values (4.35±0.80, 6.34±0.82, 8.04±0.97 mmol/L respectively) in ACC, aMCC and PCC (t=2.640, P=0.012; t=2.182, P=0.035; t=3.343, P=0.002), had significantly lower choline (Cho) 1.32±0.22 mmol/L (t=2.905, P=0.006) and glutamine and glutamate complex (Glx) 10.02±0.88 mmol/L (t=2.090, P=0.043) in PCC. Cho, total creatine (tCr), myo-Inositol (MI) and Glx levels did not differ between groups in other aforementioned regions (P>0.05). Negative correlations between the NAA ualues in the PCC and CARS (r=-0.504, P=0.020) were detected, and no significant correlation among DSM-IV, CARS, ABC and other metabolite values (P>0.05). Conclusions The biochemical changes in the preschool children with ASD in cingulate reflect the neuronal loss, structural or functional damage and cell membrane enzyme metabolic dysfunctions, may reveal the pathological basis of ASD. These results may provide noninvasive and quantitative methods for the diagnosis and prognosis evaluation of ASD child. Key words: Autism spectrum disorder; Magnetic resonance spectroscopy; Cingulate cortex; Child

Increasing the power of tumour control and normal tissue complication probability modelling in radiotherapy: recent trends and current issues

The release of a homogeneous high dose to the tumour region has been one of the cornerstones of radiotherapy (RT) treatment since its early days. According to the organ type and to the cancer histology, different doses are required in order to inactivate malignant cells, thus stopping proliferation. However, radiation-induced cell killing is a stochastic process. Tumour control probability (TCP) models have been developed in order to assign a success rate to a given RT treatment. At the same time, there is the need to keep the risks of normal tissue toxicity at an acceptable level. Normal tissue complication probability (NTCP) models provide a means of doing this. Traditionally, TCP and NTCP models combine clinical outcomes with dosimetric information in terms of dose-volume histograms (DVH). Model parameters are derived by mathematical fits to clinical observations and are subsequently used to estimate the risk of tumour relapse or toxicity. In both types of models, all of the patient dosimetric information is condensed into the DVHs, which represents a potential limitation on their descriptive and predictive power. This choice, related to historical and practical reasons, does not allow the full complexity of the 3D dose distribution in the patient to be taken into account. Neglecting these aspects might be relevant in a modern RT setting, which often includes the presence of high dose gradient regions. This has motivated research on ‘advanced’ TCP and NTCP models, able to tackle the problem by looking at a different scale, e.g. in tumour sub-regions or at the single voxel level. This is relevant not only from the purely dosimetric point of view. Increasing evidence is reported on the heterogeneity of cancer tissues, suggesting that non-uniform dose distributions could result in improved survival, for instance if targeted to take into account sub volumes with high clonogen density or hypoxic radioresistant regions. Similarly, radiation-induced side effects are part of a complex biological response, which depends not only on cell killing, but also on the inflammatory response and in some cases on the interplay among different organs. Obviously, conventional NTCP models cannot describe this scenario, and the development of more advanced mathematical tools is needed. This review will be focused on the discussion of recent studies showing possible directions for moving the field of TCP and NTCP modelling forward. Without diminishing the role and usefulness of available models, the aim is to shed light on the benefits that might be achieved by ‘enhanced’ modelling. This could represent an important step in the gradual transition of radiation therapy towards a form of precision medicine.

Characteristics of cerebral glucose metabolism on 18F-FDG PET imaging in patients with Parkinson′s disease

Objective To validate the reproducibility of abnormal cerebral metabolic characteristics in PD patients from different medical centers using 18F-FDG PET imaging. Methods A total of 108 subjects who were referred for resting-state brain 18F-FDG PET imaging were retrospectively reviewed. Thirty-three PD patients (15 males, 18 females, age: 38-79 years) and 33 age-matched healthy controls (15 males, 18 females, age: 40-77 years) underwent evaluation at Shanghai Huashan Hospital Affiliated to Fudan University. Seventeen PD patients (10 males, 7 females, age: 44-74 years) and 17 age-matched healthy controls (6 males, 11 females, age: 42-67 years) underwent evaluation at the First Affiliated Hospital of Sun Yat-sen University. SPM was used to investigate the cerebral metabolic characteristics of the patients with two-sample t test. Statistically significant voxels were obtained by using familywise error rate (FWE; P<0.05). Two sets of PD patients with abnormal glucose metabolism of brain regions were obtained and the cerebral metabolic characteristics were compared. Results Regarding the PD patients from Shanghai Huashan Hospital, the features of cerebral glucose metabolism by SPM analysis were demonstrated as follows: increased metabolism was found in the region of pons, cerebellum, thalamus, putamen and pallidum, while decreased metabolism was displayed in the region of parietal lobe and occipital lobe. The increased regions referred to 8 110 voxels and decreased regions referred to 2 810 voxels (P<0.05). The similar metabolic pattern was found in PD patients from the First Affiliated Hospital of Sun Yat-sen University. The increased metabolism was shown in the regions of pons, cerebellum, thalamus, putamen and pallidum, and referred to 15 573 voxels. The metabolism-decreased regions included parietal lobe, occipital lobe and frontal lobe, and referred to 3 945 voxels (P<0.05). Conclusions 18F-FDG PET/CT imaging results demonstrate similar metabolic pattern in PD patients from different medical centers, in whom the metabolism-increased regions are found in the pons, cerebellum, thalamus and pallidum and decreased regions were demonstrated in the parietal lobe and occipital lobe. The reproducibility from 18F-FDG PET/CT imaging provides reliable evidence for the multi-center study in the differential diagnosis of PD. Key words: Parkinson disease; Brain; Metabolism; Positron-emission tomography; Deoxyglucose

Voxel-based morphometry-diffeomorphic anatomical registration through exponentiated lie algebra algorithm evaluation of brain structural of recent-onset pediatric post-traumatic stress disorder patients

Objective To compare brain structure differences between recent-onset pediatric posttraumatic stress disorder (PTSD) patients and trauma-exposed controls without PTSD (TEC) using voxel-based morphometry (VBM)-diffeomorphic anatomical registration through exponentiated lie algebra (DARTEL) algorithm, and evaluate the relationship between volume of altered brain areas and symptom severity. Methods High-resolution 3-dimensional T1WI images were obtained from 28 first-episode treatment-naive pediatric PTSD patients group and 26 age and gender-matched TEC group within 7-15 months after a major earthquake. With the General Linear Model (GLM), gray matter volume (GMV) was compared between the two groups using VBM-DARTEL algorithm of SPM8 software running in MatLab 2012b. The statistical map cluster level had a threshold of P 113). In regions with significant group differences, the relationships between volumes of altered structures and clinician-administered PTSD scale (CAPS) and PTSD checklist (PCL) scores in patients were evaluated with age as covariates. Results Compared to TEC, pediatric PTSD patients showed GMV reduction in the left inferior frontal gyrus (IFG), precuneus, supplementary motor area (SMA), and bilateral cerebellum (voxel size=230, 118, 134, 298, 325, P<0.005). Correlation analyses showed that GMV of the left precuneus and SMA were positively correlated with CAPS scores in PTSD patients group, respectively (r=0.402, P=0.037; r=0.41, P=0.034). In addition, gray matter volume of the left SMA was positively correlated with PCL scores in PTSD group (r=0.383, P=0.049). Conclusions The characteristics of brain in recent-onset pediatric PTSD patients are mainly atrophy in some gray matter regions compared with TEC. Gray matter reduction in cerebellum may be the unique structural feature in pediatric PTSD. Key words: Stress disorders, post-traumatic; Magnetic resonance imaging; Brain

The anatomical and functional changes in the primary olfactory cortex of Alzheimer disease and mild cognitive impairment patients

Objective To determine the volume reduction of the primary olfactory cortex (POC) in patients with Alzheimer disease (AD) and investigate the potential relationship of functional olfactory activation and anatomical atrophy changes. Methods Twelve patients with AD, eight patients with mild cognitive impairment (MCI) and twenty normal controls (NC) underwent standardized UPSIT (University of Pennsylvania smell identification test) behavior smell test and neuropsychological tests. Then all of the subjects underwent the high resolution MRI and an olfactory fMRI scan on a 3T system. Volumetric measurement of the POC was conducted and the areas were also saved as a ROI which would be used during the processing of fMRI data to get the activation voxels in local region. The Kruskal-Wallis rank test was used to examine the significance of POC volume and activation in three groups, If P-value was less than 0.05,Bonferroni method was used for multiple comparisons. The correlation between the anatomical volume and functional activation was analyzed with partial correlation adjusted for age. Results The POC volume of NC, MCI and AD groups were 3024--4734, 1409--4553 and 1561--3759 mm~3, and the medians were 3749, 2752 and 2156 mm~3. The activation voxels of each group were 0--2360, 0--2160 and 0--100 mm~3, while the medians were 430, 40 and 0 mm~3. There were significant differences of both POC volume atrophy and activation between the three groups, with a trend of reduction from NC to MCI to AD group (H is 14.942 and 16.587, both P<0.05). The volume of olfactory activation at POC was highly correlated with the volume of POC (r=0.364, P=0.023). Conclusions In this study, we explored the morphological and functional changes in the POC. It is revealed that POC suffers prominent local atrophy and dysfunction as well as hippocampus in AD. These results can provide neuropathological and neurofunctional bases for olfactory deficit in Alzheimer Disease. Key words: Entorhinal cortex; Magnetic resonance imaging; Alzheimer disease; Cognition disorders

In-vivo anatomical reconstruction of the optic radiations in the human brain

The optic radiations are major white matter pathways funneling visual information from the lateral geniculate nuclei to the visual cortex in the occipital lobe. Given their relevance in visual processing and in several brain disorders, the optic radiations have been extensively investigated by using magnetic resonance imaging and diffusion tensor imaging tractography [1]. Herein, we use a powerful diffusion signal modeling, namely Constrained Spherical Deconvolution, in order to provide an exhaustive connectivity profile of the connections between the lateral geniculate nucleus and the visual cortex in the healthy brain, as well as pulvinar connectivity with visual-related structures. In addition, taking into account that visual deficits may precede motor symptoms’ onset in Parkinson’s Disease [2], we assessed whether the intracranial visual system can be involved at the early stage of the disease. Our connectivity analysis revealed that the optic radiations are mainly distributed in V1 and V2. Furthermore, we found significant alterations of optic radiations connectivity distribution in Parkinson’s Disease patients, with decreased lateral geniculate nucleus-V2 density as well as significant increase of optic radiations’ mean diffusivity. Voxel Based Morphometry analysis also showed significant reduction of visual cortical volumes and of the optic radiation in the patients group. In conclusion, our findings provide a reliable connectivity profile of the optic radiations, suggesting extrastriate-lateral geniculate nucleus connections in human brain. Finally, we showed that visual system alterations can be detected at early stages of Parkinson’s Disease.

Development of lymphatic nodes in the Chinese reference adult male voxel model (CRAM) with applications to radionuclide therapy

Development of lymphatic nodes in the Chinese reference adult male voxel model (CRAM) with applications to radionuclide therapy

Medical Applications of the PHITS Code (3): User Assistance Program for Medical Physics Computation.

DICOM2PHITS and PSFC4PHITS are user assistance programs for medical physics PHITS applications. DICOM2PHITS is a program to construct the voxel PHITS simulation geometry from patient CT DICOM image data by using a conversion table from CT number to material composition. PSFC4PHITS is a program to convert the IAEA phase-space file data to PHITS format to be used as a simulation source of PHITS. Both of the programs are useful for users who want to apply PHITS simulation to verification of the treatment planning of radiation therapy. We are now developing a program to convert dose distribution obtained by PHITS to DICOM RT-dose format. We also want to develop a program which is able to implement treatment information included in other DICOM files (RT-plan and RT-structure) as a future plan.

Regional homogeneity in internet addiction adolescents: a resting-state functional MRI

Objective To investigate the regional homogeneity (ReHo) changes of internet addiction (IA) adolescents using resting-state fMRI. Methods Twelve internet addiction adolescents and 12 healthy volunteers matched with age, gender and education level were collected from capital institute of pediatrics from October 2014 to August 2015. Mini-mental state examination was done for all subjects. Regional homogeneity of rs-fMRI were evaluated and compared between the two groups by using independent sample t-test. The correlation between ReHo values in different brain regions and hours spent online per week of the IA group was analyzed. Results Compared with normal controls, the adolescents with IA showed significant increased hours online per week (P<0.01). They also showed significant decreased ReHo in the left postcentral gyrus (129 voxels, t=4.45), left inferior parietal lobule (156 voxels, t= 5.02) and left inferior frontal gyrus (117 voxels, t=4.14). No increased ReHo region was found in the whole brain. The correlation analysis showed negative correlation between the hours spent online per week and the ReHo values of the left postcentral gyrus(r= -0.874, P<0.05), left inferior parietal lobule(r= -0.746, P< 0.05), and left inferior frontal gyrus(r= -0.695, P<0.05). Conclusion Adolescents with internet addiction have great ReHo alterations in many brain regions, which were linked to the degree of internet dependency. Key words: Behavior, addictive; Magnetic resonance imaging; Child