Purpose
Free‐water elimination DTI (FWE‐DTI) has been used widely to distinguish increases of free‐water partial‐volume effects from tissue’s diffusion in healthy aging and degenerative diseases. ...Because the FWE‐DTI fitting is only well‐posed for multishell acquisitions, a regularized gradient descent (RGD) method was proposed to enable application to single‐shell data, more common in the clinic. However, the validity of the RGD method has been poorly assessed. This study aims to quantify the specificity of FWE‐DTI procedures on single‐shell and multishell data.
Methods
Different FWE‐DTI fitting procedures were tested on an open‐source in vivo diffusion data set and single‐shell and multishell synthetic signals, including the RGD and standard nonlinear least‐squares methods. Single‐voxel simulations were carried out to compare initialization approaches. A multivoxel phantom simulation was performed to evaluate the effect of spatial regularization when comparing between methods. To test the algorithms’ specificity, phantoms with two different types of lesions were simulated: with altered mean diffusivity or with modified free water.
Results
Plausible parameter maps were obtained with RGD from single‐shell in vivo data. The plausibility of these maps was shown to be determined by the initialization. Tests with simulated lesions inserted into the in vivo data revealed that the RGD approach cannot distinguish free water from tissue mean‐diffusivity alterations, contrarily to the nonlinear least‐squares algorithm.
Conclusion
The RGD FWE‐DTI method has limited specificity; thus, its results from single‐shell data should be carefully interpreted. When possible, multishell acquisitions and the nonlinear least‐squares approach should be preferred instead.
ABSTRACT
Background and Purpose
Assessment of the essential white matter fibers of arcuate fasciculus and corticospinal tract (CST), required for preoperative planning in brain tumor patients, relies ...on the reliability of diffusion tensor imaging (DTI). The recent development of multiband DTI (mb‐DTI) based on simultaneous multislice excitation could maintain the overall quality of tractography while not exceeding standard clinical care time. To address this potential, we performed quantitative analyses to evaluate tractography results of arcuate fasciculus and CST acquired by mb‐DTI in brain tumor patients.
Methods
We retrospectively analyzed 44 patients with brain lesions who underwent presurgical single‐shot DTI (s‐DTI) and mb‐DTI. We measured DTI parameters: fractional anisotropy (FA) and mean diffusivity (MD mm2 s–1) in whole brain and tumor regions; and the tractography parameters: fiber FA, MD (mm2 s–1), volume (mm3), and length (mm) in the whole brain, arcuate fasciculus, and CST. Additionally, three neuroradiologists performed a blinded visual assessment comparing s‐DTI with mb‐DTI.
Results
The mb‐DTI showed higher mean FA and lower MD (r > .95, p < .002) in whole brain and tumor regions of interest; slightly higher fiber FA, volume, and length; and slightly lower fiber MD in whole brain, arcuate fasciculus, and CST than in s‐DTI. These differences were significant for fiber FA in all tracts; length (mm) in arcuate fasciculus; and fiber MD (mm2 s–1) and volume (mm3) in all patients with tumor involved in the arcuate fasciculus, CST, and whole brain tracts (p = .001). Visual assessment demonstrated that both techniques produced visually similar tracts.
Conclusions
This study demonstrated the clinical potential and significant advantages of preoperative mb‐DTI in brain tumor patients.
Abstract
The task of predicting the interactions between drugs and targets plays a key role in the process of drug discovery. There is a need to develop novel and efficient prediction approaches in ...order to avoid costly and laborious yet not-always-deterministic experiments to determine drug–target interactions (DTIs) by experiments alone. These approaches should be capable of identifying the potential DTIs in a timely manner. In this article, we describe the data required for the task of DTI prediction followed by a comprehensive catalog consisting of machine learning methods and databases, which have been proposed and utilized to predict DTIs. The advantages and disadvantages of each set of methods are also briefly discussed. Lastly, the challenges one may face in prediction of DTI using machine learning approaches are highlighted and we conclude by shedding some lights on important future research directions.
Schizophrenia is associated with chronic subclinical inflammation and decreased integrity of the corpus callosum (CC). Our previous study showed associations between peripheral IL-6 levels and the ...integrity of the CC. Epigenetic studies show associations between methylation of the genes related to immunological processes and integrity of the CC.
To investigate correlations between methylation status of IL-6 promotor and peripheral IL-6 levels and the integrity of the CC in schizophrenia.
The participants were 29 chronic schizophrenia patients (SCH) and 29 controls. Decreased integrity of the CC was understood as increased mean diffusivity (MD) and/or decreased fractional anisotropy (FA) in diffusion tensor imaging. Peripheral IL-6 concentrations were measured in serum samples and IL-6 promoter methylation status of 6 CpG sites was analyzed in peripheral leukocytes by pyrosequencing.
Moderate positive correlations were found between CpG1 methylation and the MD of proximal regions of the CC (CCR1–CCR3) and between CpGmean and MD of CCR1 in SCH. Weaker positive correlations were found for CpGmean with CCR2 and CCR3 and negative correlations were found for CpG1 and FA of CCR3 in SCH. Multivariate regression showed that methylation of CpG1, type of antipsychotic treatment, and their interaction were significant independent predictors of MD of CCR1 in SCH. Methylation of CpG2 was negatively correlated with serum IL-6 in SCH.
The methylation level of the IL-6 promotor region in peripheral leukocytes is associated with the integrity of the CC in schizophrenia and this association may depend on the type of antipsychotic treatment. Further studies are necessary to explain the mechanisms of the observed associations.
Introduction: The subpectoral direct-to-implant (SP-DTI) surgical technique is the standard and most common for breast reconstruction which could reduce implant visibility and palpability, and it ...manipulates the pectoralis major muscle with some post-operative complications such as muscle spasm, animation deformities, and pain while the prepectoral direct-to-implant (PP-DTI) approach leaves the muscle intact. Therefore, we conducted this meta-analysis to assess the efficacy and safety of the PP-DTI procedure after mastectomies compared to the standard breast reconstruction. Methods: We performed a comprehensive search for the following databases: PubMed, Cochrane (Medline), Web of Science, and Scopus. All studies published in English till February 2022 were included. These include randomized and non-randomized clinical trials comparing Operation Time, Duration of Hospitalization (DOH), Breast Animation Deformity (BAD), Implant loss, Wound infection and dehiscence, seroma as well as post-operative pain. The study’s quality will be assessed according to the Cochrane risk-of-bias tool for randomized trials (RoB2) and the ROBINS-I risk of bias tool to assess non-randomized studies of interventions. Results: There were 28 comparative studies including 3851 patients carried out breast reconstruction surgeries. Post-operative complications were comparable between the two groups as follows: implant loss (OR 1.17, 95% CI 0.71-1.94), wound dehiscence (OR 0.76, 95% CI 0.43-1.32), wound infection (OR 1.09, 95% CI 0.78-1.53), and seroma (OR 0.78, 95% CI 0.56-1.09). The PP-DTI group was significantly less likely to develop BAD compared to SP-DTI group (OR 0.02, 95% CI 0.00-0.12). Patients undergoing PP-DTI reconstruction had significantly reduced postoperative pain (SMD -0.55, 95% CI -0.78 - -0.32). Operation time and DOH were significantly lower among PP-DTI group ((SMD -0.35, 95% CI -0.61 - -0.08), (SMD -0.89, 95% CI -1.48 - -0.30, respectively)). Conclusion Following mastectomy, PP-DTI breast reconstruction significantly reduced post-operative pain, BAD, DOH, intra-operative time compared with SP-DTI reconstruction, although there was no significant difference in complication rate. A PP-DTI is a simple and safe alternative to the subpectoral technique allowing early discharge and improving patient's quality of life. Future well-designed multicenter randomized controlled trials that compare two approaches and discuss the cost-effectiveness are needed. Keywords: PP-DTI, SP-DTI, Meta-analysis, cosmetics.
Purpose
To develop a deep learning–based reconstruction framework for ultrafast and robust diffusion tensor imaging and fiber tractography.
Methods
SuperDTI was developed to learn the nonlinear ...relationship between DWIs and the corresponding diffusion tensor parameter maps. It bypasses the tensor fitting procedure, which is highly susceptible to noises and motions in DWIs. The network was trained and tested using data sets from the Human Connectome Project and patients with ischemic stroke. Results from SuperDTI were compared against widely used methods for tensor parameter estimation and fiber tracking.
Results
Using training and testing data acquired using the same protocol and scanner, SuperDTI was shown to generate fractional anisotropy and mean diffusivity maps, as well as fiber tractography, from as few as six raw DWIs, with a quantification error of less than 5% in all white‐matter and gray‐matter regions of interest. It was robust to noises and motions in the testing data. Furthermore, the network trained using healthy volunteer data showed no apparent reduction in lesion detectability when directly applied to stroke patient data.
Conclusions
Our results demonstrate the feasibility of superfast DTI and fiber tractography using deep learning with as few as six DWIs directly, bypassing tensor fitting. Such a significant reduction in scan time may allow the inclusion of DTI into the clinical routine for many potential applications.
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