We developed a deep learning–based super-resolution model for prostate MRI. 2D T2-weighted turbo spin echo (T2w-TSE) images are the core anatomical sequences in a multiparametric MRI (mpMRI) protocol. These images have coarse through-plane resolution, are non-isotropic, and have long acquisition times (approximately 10–15 min). The model we developed aims to preserve high-frequency details that are normally lost after 3D reconstruction. We propose a novel framework for generating isotropic volumes using generative adversarial networks (GAN) from anisotropic 2D T2w-TSE and single-shot fast spin echo (ssFSE) images. The CycleGAN model used in this study allows the unpaired dataset mapping to reconstruct super-resolution (SR) volumes. Fivefold cross-validation was performed. The improvements from patch-to-volume reconstruction (PVR) to SR are 80.17%, 63.77%, and 186% for perceptual index (PI), RMSE, and SSIM, respectively; the improvements from slice-to-volume reconstruction (SVR) to SR are 72.41%, 17.44%, and 7.5% for PI, RMSE, and SSIM, respectively. Five ssFSE cases were used to test for generalizability; the perceptual quality of SR images surpasses the in-plane ssFSE images by 37.5%, with 3.26% improvement in SSIM and a higher RMSE by 7.92%. SR images were quantitatively assessed with radiologist Likert scores. Our isotropic SR volumes are able to reproduce high-frequency detail, maintaining comparable image quality to in-plane TSE images in all planes without sacrificing perceptual accuracy. The SR reconstruction networks were also successfully applied to the ssFSE images, demonstrating that high-quality isotropic volume achieved from ultra-fast acquisition is feasible.
AIM: To determine the proliferative potential and the maintenance of stem cell activity in stored human limbal tissues, and correlate this with the preservation time, cell viability and the expression of stem cell markers.METHODS: Thirty limbal rims were split into 4 parts and stored in corneal preservation medium at 4℃ for 0, 1, 4, or 7 days. The limbal stem cell and mitotic markers P63, CK19, proliferating cell nuclear antigen (PCNA), and Ki67 were determined by immunohistochemical staining. The proliferative potential of limbal epithelial cells was assessed by cell viability, the ability of generating stratified epithelium, and colony forming assay.RESULTS: The stored tissues maintained limbal stratified structure to 7 days and exhibited comparable expression level of stem cell and mitotic markers. The proportion of viable cells decreased with the prolonged preservation time, while colony forming efficiency decreased from the 1st day and disappeared at the 4th day. When inoculated on amniotic membrane, the cells preserved for 1 day formed a stratified epithelium, while the cells from 4 days’ preservation formed a discontinuous layer.CONCLUSION: The colony forming efficiency of limbal epithelial stem/progenitor cells decreased rapidly with the increasing preservation time, while the expression level of markers and capacity of forming epithelial monolayer on amniotic membrane decreased gradually. The limbal epithelial stem cells lost their function earlier than the lost expression level of stem cell markers. This may help us to better choose the appropriate preservation grafts for future limbal stem cell transplantation. 相似文献
Recently, a variety of 4-substituted Hantzsch esters (XRH) with different structures have been widely researched as alkylation reagents in chemical reactions, and the key step of the chemical process is the elementary step of XRH˙+ releasing R˙. The purpose of this work is to investigate the essential factors which determine whether or not an XRH is a great alkylation reagent using density functional theory (DFT). This study shows that the ability of an XRH acting as an alkylation reagent can be reasonably estimated by its ΔG≠RD(XRH˙+) value, which can be conveniently obtained through DFT computations. Moreover, the data also show that ΔG≠RD(XRH˙+) has no simple correlation with the structural features of XRH, including the electronegativity of the R substituent group and the magnitude of steric resistance; therefore, it is difficult to judge whether an XRH can provide R˙ solely by experience. Thus, these results are helpful for chemists to design 4-substituted Hantzsch esters (XRH) with novel structures and to guide the application of XRH as a free radical precursor in organic synthesis.This work presents a convenient computation method to estimate whether a 4-substituted Hantzsch ester can be a good alkyl radical donor.相似文献
The goal was to develop models for predicting long-term quality of life (QOL) after breast cancer surgery.
Methods
Data were obtained from 203 breast cancer patients who completed the SF-36 health survey before and 2 years after surgery. Two of the models used to predict QOL after surgery were artificial neural networks (ANNs), which included one multilayer perceptron (MLP) network and one radial basis function (RBF) network. The third model was a multiple regression (MR) model. The criteria for evaluating the accuracy of the system models were mean square error (MSE) and mean absolute percentage error (MAPE).
Results
Compared to the MR model, the ANN-based models generally had smaller MSE values and smaller MAPE values in the test data set. One exception was the second year MSE for the test value. Most MAPE values for the ANN models ranged from 10 to 20 %. The one exception was the 6-month physical component summary score (PCS), which ranged from 23.19 to 26.86 %. Comparison of criteria for evaluating system performance showed that the ANN-based systems outperformed the MR system in terms of prediction accuracy. In both the MLP and RBF networks, surgical procedure type was the most sensitive parameter affecting PCS, and preoperative functional status was the most sensitive parameter affecting mental component summary score.
Conclusion
The three systems can be combined to obtain a conservative prediction, and a combined approach is a potential supplemental tool for predicting long-term QOL after surgical treatment for breast cancer.
Relevance
Patients should also be advised that their postoperative QOL might depend not only on the success of their operations but also on their preoperative functional status. 相似文献