Objective: Quantitative \(T_1\rho\) imaging has potential for assessment of biochemical alterations of liver pathologies. Deep learning methods have been employed to accelerate quantitative ...\(T_1\rho\) imaging. To employ artificial intelligence-based quantitative imaging methods in complicated clinical environment, it is valuable to estimate the uncertainty of the predicated \(T_1\rho\) values to provide the confidence level of the quantification results. The uncertainty should also be utilized to aid the post-hoc quantitative analysis and model learning tasks. Approach: To address this need, we propose a parametric map refinement approach for learning-based \(T_1\rho\) mapping and train the model in a probabilistic way to model the uncertainty. We also propose to utilize the uncertainty map to spatially weight the training of an improved \(T_1\rho\) mapping network to further improve the mapping performance and to remove pixels with unreliable \(T_1\rho\) values in the region of interest. The framework was tested on a dataset of 51 patients with different liver fibrosis stages. Main results: Our results indicate that the learning-based map refinement method leads to a relative mapping error of less than 3% and provides uncertainty estimation simultaneously. The estimated uncertainty reflects the actual error level, and it can be used to further reduce relative \(T_1\rho\) mapping error to 2.60% as well as removing unreliable pixels in the region of interest effectively. Significance: Our studies demonstrate the proposed approach has potential to provide a learning-based quantitative MRI system for trustworthy \(T_1\rho\) mapping of the liver.
In contrast to chronic hepatitis C (CHC), few studies had been performed in assessing non-invasive models for predicting significant fibrosis or cirrhosis in chronic hepatitis B (CHB) patients. We ...aimed to evaluate non-invasive markers for diagnosing significant fibrosis-cirrhosis in patients with CHB, and to evaluate accuracy of models from CHC in CHB patients. Patients and methods: Liver biopsies from consecutive treatment-naive CHB patients were evaluated histologically by a pathologist blindly, using the Ishak score. Patients were divided randomly into a training (65%) and a validation sets (35%). Markers of fibrosis were evaluated by univariate followed by multivariate analysis in the training set. Area under receiver operating characteristics curve (AUROC) was assessed and validated in the training set. AUROC of aspartate aminotransferase (AST), AST-alanine aminotransferase (ALT) ratio, and AST-platelets ratio index (APRI) (derived from studies from CHC) in diagnosing significant fibrosis-cirrhosis were also assessed. Results: Two-hundred and eighteen CHB patients were evaluated: 83% male, 86% Chinese, 47% having significant fibrosis, 19% having cirrhosis. Platelets were the only factor significantly associated with significant fibrosis and cirrhosis at multivariate analysis but the AUROC was only modest at 0.63 and 0.73, respectively. Models derived from studies from CHC were even less accurate. Conclusion: Models with non-invasive markers in predicting histology from CHC patients were unsuitable for CHB patients. No variables consisting of simple and readily available markers were able to predict cirrhosis accurately in patients with CHB.
To assess the development of white matter and cerebral metabolite changes during and after treatment in children with acute lymphoblastic leukemia.
Twenty-three children (10 boys, mean age of 6.3 ...years; 13 girls, mean age of 6.6 years) with acute lymphoblastic leukemia were examined prospectively with magnetic resonance (MR) imaging and MR spectroscopy at 0, 8, and 20 weeks and 1, 2, and 3 years after diagnosis. White matter changes were diagnosed on the basis of hyperintense abnormalities on T2-weighted MR images. Single-voxel hydrogen 1 MR spectroscopy results from the right frontoparietal region of 21 children who received intravenous high-dose methotrexate were analyzed for cerebral metabolite changes. Multilevel models were used to assess the change in metabolites from baseline levels at subsequent follow-up.
At 20 weeks, MR spectroscopy showed a significant reduction (P <.05) of mean N-acetylaspartate to choline ratio and increase in mean choline to creatine ratio (P <.05) in the children given high-dose methotrexate. This decline in N-acetylaspartate to choline ratio subsequently reversed and increased, possibly because of normal age-related brain maturation. Seventeen of 21 (81%) children showed metabolite changes at MR spectroscopy, while five of 22 (23%) showed white matter changes at MR imaging at 20 weeks. One more child developed white matter changes at 32 weeks. The associated changes resolved or reduced with time.
MR spectroscopy demonstrated metabolite changes in the brain after high-dose methotrexate treatment in the absence of structural white matter abnormalities at MR imaging. MR spectroscopy might thus be a more sensitive method of monitoring the effects of high-dose methotrexate in the brain.
Since the Chinese were officially plugged into the virtual community in 1994, the usage of the internet in the country has developed at an incredible rate. By the end of 2008, there were ...approximately 298 million netizens in China, a number which surpasses that of the U.S. and ranks China the highest user in the world. The rapid development of the online Chinese community has not only boosted the information flow among citizens across the territory, but has also created a new form of social interaction between the state, the media, various professionals and intellectuals, as well as China's ordinary citizens. Although the subject of this book is online Chinese nationalism, which to a certain extent is seen as a pro-regime phenomenon, the emergence of an online civil society in China intrinsically provides some form of supervision of state power-perhaps even a check on it. The fact that the party-state has made use of this social interaction, while at the same time remaining worried about the negative impact of the same netizens, is a fundamental characteristic of the nature of the relationship between the state and the internet community. Many questions arise when considering the internet and Chinese nationalism. Which are the most important internet sites carrying online discussion of nationalism related to the author's particular area of study? What are the differences between online nationalism and the conventional form of nationalism, and why do these differences exist? Has nationalist online expression influenced actual foreign policy making? Has nationalist online expression influenced discourse in the mainstream mass media in China? Have there been any counter reactions towards online nationalism? Where do they come from? Online Chinese Nationalism and China's Bilateral Relations seeks to address these questions.
Although the ideal of companionate marriage has gradually been established in Hong Kong, demographic trends from the 1980s reflect greater marital and family instability. In the years to come, adult ...fulfilment is likely to be found in various ways: throug
Papillary carcinoma of the breast is a rare breast carcinoma. It can be classified into invasive and noninvasive types. It can also be classified into intracystic and intraductal papillary carcinoma. ...Different radiological features are found to be associated with different histological types. Pitfalls are found to be associated with fine needle aspiration and core biopsy in the evaluation of papillary lesions. It is therefore important for radiologists to diagnose papillary carcinoma for proper management of the patients.
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