A novel transcranial MR Guided focused ultrasound method based on the ultrashort echo time skull acoustic model and phase retrieval techniques.

Transcranial ultrasound stimulation (TUS) has been clinically applied as a neuromodulation tool. Particularly, the phase array ultrasound can be applied in TUS to non-invasively focus on the cortex or deep brain. However, the vital phase distortion of the ultrasound induced by the skull limits its clinical application. In the current study, we aimed to develop a hybrid method that combines the ultrashort echo time (UTE) magnetic resonance imaging (MRI) sequences with the prDeep technique to achieve focusing ventral intermediate thalamic nucleus (VIM). The time-reversal (TR) approach of the UTE numerical acoustic model of the skull combined with the prDeep algorithm was used to reduce the number of iterations. The skull acoustic model simulation therapy process was establish to valid this method's prediction and focus performance, and the classical TR method were considered as the gold standard (GS). Our approach could restore 75% of the GS intensity in 25 iteration steps, with a superior the noise immunity. Our findings demonstrate that the phase aberration caused by the skull can be estimated using phase retrieval techniques to achieve a fast and accurate transcranial focus. The method has excellent adaptability and anti-noise capacity for satisfying complex and changeable scenarios.

Mapping individual structural covariance network in development brain with dynamic time warping.

A conspicuous property of brain development or maturity is coupled with coordinated or synchronized brain structural co-variation. However, there is still a lack of effective approach to map individual structural covariance network. Here, we developed a novel individual structural covariance network method using dynamic time warping algorithm and applied it to delineate developmental trajectories of topological organizations of structural covariance network from childhood to early adulthood with a large sample of 655 individuals from Human Connectome Project-Development dataset. We found that the individual structural covariance network exhibited small-worldness property and the network global topological characteristics including small-worldness, global efficiency, local efficiency, and modularity linearly increase with age while the shortest path length linearly decreases with age. The nodal topological properties including betweenness and degree increased with age in language and emotion regulation related brain areas, while it decreased with age mainly in visual cortex, sensorimotor area, and hippocampus. Moreover, the topological attributes of structural covariance network as features could predict the age of each individual. Taken together, our results demonstrate that dynamic time warping can effectively map individual structural covariance network to uncover the developmental trajectories of network topology, which may facilitate future investigations to establish the links of structural co-variations with respect to cognition and disease vulnerability.

SPatiotemporal-ENcoded acoustic radiation force imaging of focused ultrasound.

Neuromodulation technology has provided novel therapeutic approaches for diseases caused by neural circuit dysfunction. Transcranial focused ultrasound (FU) is an emerging neuromodulation approach that combines noninvasiveness with relatively sharp focus, even in deep brain regions. It has numerous advantages such as high precision and good safety in neuromodulation, allowing for modulation of both peripheral and central nervous systems. To ensure accurate treatment targeting in FU neuromodulation, a magnetic resonance acoustic radiation force imaging (MR-ARFI) sequence is crucial for the visualization of the focal point. Currently, the commonly used 2D Spin Echo ARFI (2D SE-ARFI) sequence suffers from the long acquisition time, while the echo planar imaging ARFI (EPI-ARFI) sequence with a shorter acquisition time is vulnerable to the magnetic field inhomogeneities. To address these problems, we proposed a spatiotemporal-encoded acoustic radiation force imaging sequence (i.e., SE-SPEN-ARFI, shortened to SPEN-ARFI) in this study. The displacement at the focal spot obtained was highly consistent with that of the SE-ARFI sequence. Our research shows that SPEN-ARFI allows for rapid image acquisition and has less image distortions even under great field inhomogeneities. Therefore, a SPEN-ARFI sequence is a practical alternative for the treatment planning in ultrasound neuromodulation.

Effect of regional intrinsic activity following two kinds of theta burst stimulation on precuneus.

Theta burst stimulation (TBS) has been widely used in the treatment of mental disorders, but the cerebral functional difference between intermittent TBS (iTBS) and continuous TBS (cTBS) after one single session of stimulation is not clear. Here we applied resting-state functional magnetic resonance imaging (RS-FMRI) to evaluate the alterations in intrinsic brain activity after iTBS and cTBS in the precuneus. We recruited 32 healthy young adults and performed a single session each of iTBS and cTBS at a 1-week interval. RS-fMRI was collected at baseline before and immediately after the stimulation. Parameters for regional brain activity (ALFF/fALFF/ReHo) and functional connectivity (FC) with the stimulated site of the precuneus after iTBS and cTBS were calculated and compared between each stimulation using a paired t-test. Correlation analysis among those parameters was calculated to explore whether changes in functional connectivity were associated with local spontaneous activity. After iTBS stimulation, fALFF increased in the bilateral precuneus, while fALFF decreased in the bilateral middle temporal gyrus. Reductions in precuneus FC were found in the bilateral cuneus, superior occipital gyrus, superior temporal gyrus, precentral gyrus, and postcentral gyrus, which correlated with regional activity. After cTBS, fALFF decreased in the bilateral insula, and precuneus FC was decreased in the bilateral inferior occipital gyrus and increased in the thalamus. In the current study, we observed that one session of iTBS or cTBS could cause inhibitory effects in remote brain regions, but only iTBS caused significant local activation in the target region.

Efficacy and safety of repetitive transcranial magnetic stimulation in children and adolescents with depression: A systematic review and preliminary meta-analysis.

BACKGROUND: Repetitive transcranial magnetic stimulation (rTMS) benefits adults with depression while its efficacy and safety in children and adolescents with major depressive disorder (MDD) remain unclear. We conducted a preliminary meta-analysis here to objectively appraise rTMS in the youth with MDD to inform future research and clinical practice. METHODS: We searched Pubmed, Embase, Web of Science and the Cochrane Central Register of Controlled Trials from their inception to December 1, 2021. Studies with a control group or self-controlled designs and evaluating the Hamilton Depression Scale (HAM-D) or the Children's Depression Rating Scale-Revised (CDRS-R) at baseline and post-rTMS treatment were included. Two reviewers independently selected eligible studies, retrieved data in a structured fashion and assessed studies' quality. Hedges'g with 95 % confidence intervals and withdrawal rate with 95 % confidential intervals were separately used to evaluate the efficacy and safety of rTMS. RESULTS: Thirteen studies with six datasets (165 patients, 61.8 % female, age range from 10 to 25 years old) were included and our meta-analysis found children and adolescents with MDD benefited from rTMS treatment (Hedges'g 1.37, 95 % CI 0.85 to 1.90, P = 0.001). In addition, 4 % of patients (95 % CI 0.02 to 0.09) withdrew during rTMS treatment for reasons including fear, mood swings, suicide ideation and adverse events. LIMITATIONS: This conclusion is tempered by a small number of studies included and a potentially existing placebo effect. CONCLUSIONS: Our findings suggest rTMS could benefit children and adolescents with MDD in a relatively safe manner, and this result may help guide clinical practice.

Application of graph theory across multiple frequency bands in drug-naïve obsessive-compulsive disorder with no comorbidity.

Recently, graph theoretical analysis based on resting-state functional magnetic resonance imaging has provided a means of investigating the complex brain connectome in obsessive-compulsive disorder (OCD) patients. However, these studies have been restricted to spontaneous blood oxygen level-dependent (BOLD) signals with frequency bands between 0.01 and 0.08 Hz, and the parameters from graph theory across multiple frequency bands have seldom been studied. Here, we calculated global metrics (small-worldness, global efficiency and modularity) and nodal metrics (degree centrality, betweenness centrality, nodal clustering coefficient and shortest path) at four different frequency bands (slow-2 (0.199-0.25 Hz), slow-3 (0.074-0.198 Hz), slow-4 (0.027-0.073 Hz) and slow-5 (0.01-0.027 Hz), from 0.01 to 0.25 Hz) in seventy-three OCD patients and ninety healthy controls. The analyses were also calculated in traditional low-frequency bands (0.01-0.08 Hz) for reference. For the global metrics, the OCD patients showed increased small-worldness and modularity only in the slow-3 band. For the local metrics, we observed a frequency-dependent characteristic, with the main significant differences in regions including the right precentral gyrus, occipital region, right anterior cingulum cortex and fusiform cortex. Our results suggested frequency-specific abnormalities of the brain connectome in OCD and the future studies may need to consider different frequency bands when measuring spontaneous activity in the brain.

Characterizing multiscale modular structures in medication-free obsessive-compulsive disorder patients with no comorbidity.

Brain networks exhibit signatures of modular structure, which maintains a fine trade-off between wiring cost and efficiency of information transmission. Alterations in modular structure have been found in patients with obsessive-compulsive disorder (OCD). However, previous studies were focused on a single scale (i.e., modularity or intra/intermodular connectivity) for investigation. Here, we recruited 92 OCD patients and 90 healthy controls. A comprehensive analysis was performed on modular architecture alterations in the voxelwise functional connectome at the "global" (modularity), "meso" (modular segregation and within- and between-module connections), and "local" (participation coefficients, PC) scales. We also examined the correlation between modular structure metrics and clinical symptoms. The findings revealed that (1) there was no significant group difference in global modularity; (2) both primary modules (visual network, sensorimotor network) and high-order modules (dorsal attention network, frontoparietal network) exhibited lower modular segregation in OCD patients, which was mainly driven by increased numbers of between-module connections; and (3) OCD patients showed higher PC in several connectors including the bilateral middle occipital gyri, left medial orbital frontal gyrus, left superior frontal gyrus, left posterior cingulate gyrus, right superior temporal gyrus and right middle frontal gyrus, and lower PC in the right lingual gyrus. Moreover, these alterations in modular structure were associated with clinical symptoms in patients. Our findings provide further insights into the involvement of different modules in functional network dysfunction in OCD from a connectomic perspective and suggest a synergetic mechanism of module interactions that may be related to the pathophysiology of OCD.

Prolactin mediates the relationship between regional gray matter volume and postpartum depression symptoms.

BACKGROUND: Pospartum Depression (PPD) causes significant adverse effects on mothers and their offspring. The condition is considered to have multiple pathogenic factors. However, the underlying neural basis of these factors keeps unclear. METHODS: A group of 86 patients with PPD and 74 Healthy Postnatal Women (HPW) were enrolled in this structural Magnetic Resonance Imaging (MRI) study. Between-groups differences in regional gray matter volume (rGMV) were measured and association and mediation analyses were performed to investigate the relationship between rGMV, PPD severity and a range of demographic/clinical factors which could contribute to PPD. RESULTS: Relative to HPW, PPD patients had higher scores indicating adverse effects on most questionnaires and higher prolactin levels, as well as increased rGMV in left dorsolateral prefrontal cortex (DLPFC) and right anterior insular (anI). In PPD patients, rGMV in right anI was positively correlated with prolactin level, PPD severity, and the number of children raised, whereas rGMV in left DLPFC was negatively correlated with education and age. Besides, prolactin level was found to mediate the association between rGMV in anI and PPD symptoms. LIMITATIONS: Potentially factors such as fertility or delivery pattern were not studied. CONCLUSION: Our results provide information on the risk and protective factors, and rGMV abnormalities, associated with PPD. The finding that prolactin level mediated the impact of rGMV in right anI on PPD symptoms is a potential mechanism for explaining the association between brain structure and PPD symptoms. Increased understanding of the neuro-pathophysiology of PPD is important for early diagnosis and treatment.

Brain Entropy Study on Obsessive-Compulsive Disorder Using Resting-State fMRI.

Object: Brain entropy is a potential index in the diagnosis of mental diseases, but there are some differences in different brain entropy calculation, which may bring confusion and difficulties to the application of brain entropy. Based on the resting-state function magnetic resonance imaging (fMRI) we analyzed the differences of the three main brain entropy in the statistical significance, including approximate entropy (ApEn), sample entropy (SampEn) and fuzzy entropy (FuzzyEn), and studied the physiological reasons behind the difference through comparing their performance on obsessive-compulsive disorder (OCD) and the healthy control (HC). Method: We set patients with OCD as the experimental group and healthy subjects as the control group. The brain entropy of the OCD group and the HC are calculated, respectively, by voxel and AAL region. And then we analyzed the statistical differences of the three brain entropies between the patients and the control group. To compare the sensitivity and robustness of these three kinds of entropy, we also studied their performance by using certain signal mixed with noise. Result: Compare with the control group, almost the whole brain's ApEn and FuzzyEn of OCD are larger significantly. Besides, there are more brain regions with obvious differences when using ApEn comparing to using FuzzyEn. There was no statistical difference between the SampEn of OCD and HC. Conclusion: Brain entropy is a numerical index related to brain function and can be used as a supplementary biological index to evaluate brain state, which may be used as a reference for the diagnosis of mental illness. According to an analysis of certain signal mixed with noise, we conclude that FuzzyEn is more accurate considering sensitivity, stability and robustness of entropy.

Efficacy and tolerability of repetitive transcranial magnetic stimulation for the treatment of obsessive-compulsive disorder in adults: a systematic review and network meta-analysis.

Repetitive transcranial magnetic stimulation (rTMS) has been widely used as an alternative treatment for obsessive-compulsive disorder (OCD). However, the most effective rTMS parameters, such as the targets and stimulation frequencies, remain controversial. Therefore, we aimed to compare and rank the efficacy and tolerability of different rTMS strategies for OCD treatment. We searched five electronic databases from the date of their inception to March 25, 2020. Pairwise meta-analyses and network meta-analyses were performed to synthesize data. We assessed the quality of evidence using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) framework. Twenty-two eligible randomized controlled trials (RCTs) were included. For efficacy, low-frequency (LF) rTMS over the dorsolateral prefrontal cortex (DLPFC; mean difference (MD) 6.34, 95% credible interval (CrI) 2.12-10.42) and supplementary motor area (MD 4.18, 95% CrI 0.83-7.62), and high-frequency rTMS over the DLPFC (MD 3.75, 95% CrI 1.04-6.81) were more effective than sham rTMS. Regarding tolerability, all rTMS treatment strategies were similar to the sham rTMS. The estimated ranking probabilities of treatments showed that LF-rTMS over the DLPFC might be the most effective intervention among all rTMS strategies. However, the quality of evidence regarding efficacy was evaluated as very low. Current evidence suggested a marginal advantage for LF-rTMS over the DLPFC on OCD treatment. High-quality RCTs with low selection and performance bias are needed to further verify the efficacy of specific rTMS strategies for the OCD treatment.

Simulation and Experimental Study on Doubled-Input Capacitively Coupled Contactless Conductivity Detection of Capillary Electrophoresis.

In this contribution, we optimize the structure of double-input capacitively coupled contactless conductivity detector (DIC4D) that proposed before by our group and successfully applied it in the capillary electrophoresis of inorganic ion analysis. Furthermore, we present the detail theoretical analysis and simulation to exploring the working mechanism of DIC4D. Compared with C4D, under identical experimental conditions and by using the same current-to-voltage converter, both the theoretical and experimental results suggest that the effectiveness and feasibility of DIC4D. The improved DIC4D diminished the baseline drift effects in C4D, provides lower noise, higher sensitivity and notably stable baseline. The LODs of DIC4D are 1.0 µM for K+ and 1.5 µM for Li+ (S/N = 3). DIC4D provides a better linear relationship (R = 0.997 and 0.998 for K+ and Li+, respectively) with the range of 2.0 µM ~ 2.5 mM.

Impact of iterative model reconstruction combined with dose reduction on the image quality of head and neck CTA in children.

This study aimed to evaluate the imaging quality of head and neck computed tomographic angiography (CTA) in pediatric patients at a lowered radiation dose by combining an iterative model reconstruction (IMR) with low voltage scanning. Eighty-three pediatric patients were randomized into two groups as follows: Group A (n = 42), 100 kV/50 ml contrast media (CM), using filtered back projection (FBP); and Group B (n = 41), 80 kV/30 ml CM, using IMR. The enhanced CT value of the arteries, the image noise, the signal-to-noise ratio (SNR)/contrast-to-noise ratio (CNR), the image quality, the effective radiation dose (ED) and the iodine intake were compared between the two groups. The mean ED and iodine intake of group B were reduced by 69.8% and 40.0%, respectively, compared to those of group A. The mean CT values of the arteries in group B were higher than those in group A (p < 0.01), whereas the image noise of group B was lower than that of group A (p < 0.01). Group B exhibited a better image quality and a higher mean CNR/SNR than that of group A (p < 0.01). Compared to FBP, IMR in head and neck CTA enables a significant reduction in the radiation dose while preserving the diagnostic image quality. Thus, IMR, combined with low tube voltage scanning, provided an excellent solution for improving the image quality of craniocervical vessels in children.

[Motion-in-depth Perception and Static Stereopsis of Patients with Strabismics].

OBJECTIVE: To determine the role of motion-in-depth perception and static stereopsis in strabismics, and factors associated with the perception of motion-in-depth. METHODS: A total of 84 strabismic patients (including 57 intermittent exotropes, 12 constant exotropes and 15 esotropes) and 16 normal controls were recruited. Binocular fusion ability, static stereopsis and motion-in-depth perception were tested using the computer-generated stereoscopic stimuli. The correlations between these tests were analyzed. RESULTS: There was a significant correlation between motion-in-depth perception and static stereopsis in strabismics. Only patients with static stereopsis demonstrated the perception of motion-in-depth. A positive correlation was found between motion-in-depth perception thresholds and static stereopsis in intermittent exotropes. All participants in the control group had motion-in-depth perception and static stereopsis. The participants with stereopsis had significantly lower thresholds than those with strabismus (P<0.01). The perception of motion-in-depth varied with the type of strabismus: 87.7% of the intermittent exotropes exhibited motion-in-depth perception, whereas none of the constant strabismics were able to pass the motion-in-depth perception tests. The perception of motion-in-depth was correlated with the presence of binocular fusion. CONCLUSIONS: Motion-in-depth perception is correlated with static stereopsis in strabismics. The perception of motion-in-depth varies with the type of strabismus: only intermittent exotropes have the perception of motion-in-depth.

Investigation of different boundary treatment methods in Monte-Carlo simulations of diffusion NMR.

PURPOSE: To enrich and develop more convenient and effective boundary treatment method in Monte-Carlo simulation of restricted diffusion nuclear magnetic resonance. METHODS: The conventional approach used in treating boundary behaviors of restricted diffusion is the elastic boundary reflection. Because random walk is not dynamic process, other boundary treatments such as inelastic reflection are acceptable and probably simplify the programming of diffusion nuclear magnetic resonance simulation. The present study simulated the pulse gradient spin echo nuclear magnetic resonance by employing three boundary models, i.e., the elastic boundary reflection, the non-elastic boundary reflection, and the equal-step-length random leap. Their effects on precision, convergence, and calculation efficiency were investigated, as well as the effects of non-fixed boundary reflection step-length drawn from a Gaussian distribution in barrier-crossing steps. RESULTS: The results show no obvious difference in convergences and precisions for different methods when the relative step-length is sufficiently small. Compared with the traditional approach, the required computation time of the latter two was reduced in some degree. CONCLUSION: Boundary treatments based on inelastic reflection are a feasible choice in Monte-Carlo simulation of nuclear magnetic resonance, and in comparison with the conventional approach, it not only renders programming more convenience but also possibly lead to higher calculating efficiency.

Proton MR spectroscopy of central neurocytoma using short and long echo time: new proofs for the existence of glycine and glutamate.

RATIONALE AND OBJECTIVES: Central neurocytomas (CNCs) are rare benign tumors typically located in the lateral ventricle of the central nervous system. The authors report five patients with CNCs and review 16 previously published studies that included 52 patients with CNCs to explore the magnetic resonance spectroscopic features of CNCs. MATERIALS AND METHODS: Five patients with CNCs were retrospectively reviewed. They were examined using point-resolved spectroscopic series with short and/or long echo times. The integrals of choline, creatine, and the 3.55-ppm peak were determined using Magnetic Resonance User Interface software, and the metabolite ratios relative to creatine were obtained. In two cases, T2 relaxation times of choline and the metabolite resonance at 3.55 ppm were calculated using data points acquired with different echo times and an exponential decay model. RESULTS: Consistent with previously published studies, all five patients showed highly increased choline and reduced N-acetylaspartate and creatine. Four patients in the present study and 35 in published data demonstrated prominent peaks at 3.55 ppm, which were assigned to glycine because of its relaxation pattern and long T2 relaxation time. In addition, increased in vivo glutamate and glutamine was also confirmed in three patients examined with short echo times. Alanine and lactate peaks were observed in three and two patients, respectively. CONCLUSIONS: The present study shows that the 3.55-ppm peak characteristic of CNC should be assigned to glycine according to its T2 relaxation time. Besides increased glycine and choline, the presence of glutamate or glutamine, which appears on series with short echo times, may further confirm the diagnosis of CNC.

[Analysis on DQA protocol of fMRI].

Our purpose is to introduce and analyze the data quality assurance (DQA) protocol of functional magnetic resonance imaging (fMRI). A water phantom was scanned to get DQA indexes. An fMRI sequence was used to get signal noise ratio (SNR) and Drift, which was calculated from maximum difference ratio of the average signal intensity in the region of interest (ROI) of image serials. The long period application of this method demonstrated that this DQA protocol can reflect imaging performance and the state of stability of the MRI scanner. Some application experience and discussion involved in DQA were also presented here.

[A research on JPEG2000 used in DICOM store service].

In view of the fact that the large quantities of data contained in the medical image do not have a favorable setting for effective storage and transmission in the existing network, we have developed a JPEG2000 DICOM image compression kit using VC++, and we have realized the medical image storage service according to the C-STORE rule of DICOM standard. The results showed that the medical image processed by JPEG2000 compression algorithm not only greatly saved the storage space, but also reduced the band width needed by transmission. In this paper is discussed the DICOM image compressed by JPEG2000 compression algorithm in DICOM strorage service application. The significance of JPEG2000 compression algorithm in the development of picutre archiving and communication systems (PACS) and telemedicine is also explained.

[Study of stress distribution in mandibular first premolar restored by composite resin with root screw of different length in different occlusion].

OBJECTIVE: To investigate stress distribution in mandibular first premolar restored by composite resin with root screw of different length in different occlusion. METHODS: An three dimensional finite element model of mandibular first premolar restored by composite resin with root screw was constructed by using spiral CT image reconstruction technique, Mimics, Pro/Engineer, Pro/Mechanica software. Based on this model, stress distribution in dentin, composite resin and root screw was analyzed in the situation of different screw length and different occlusion. RESULTS: When the occlusion was tripod contact and cusp tip-ovoid fossa contact, the stress of dentin, composite resin and root screw were all much less than their compressive strength. And also in this situation, the stress of bond surface between the composite resin and dentin was less than the bond strength of composite resin. The screw was longer but no more than 8 mm, the dentin stress distributes better. CONCLUSION: In the restoration of large area mandibular first premolar crown defection, tripod contact and cusp tip-ovoid fossa contact with 8 mm root screw is recommended.

[The research and implementation of DICOM interface of medical imaging devices].

PACS (Picture Archiving and Communication Systems) is the hot spot of hospital information construction research and DICOM (Digital Imaging and Communication in Medicine) is the international standard about data compression and translation of medical image and relational information. Supporting DICOM standard is the necessary condition for medical image devices to join into PACS net. In making reforms in the old fashioned medical devices in hospitals, it is necessary to add DICOM interface for medical image devices. In this paper, DICOM information model is introduced and software system is implemented with Visual C + + programming, especially the writing, reading and C-STORE service in communication function are introduced in detail.