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MRI-derived quantification of hepatic vessel-to-volume ratios in chronic liver disease using a deep learning approach

arXiv.org Artificial Intelligence

Computational Imaging Research Lab, Department of Biomedical Imaging and Image - guided Therapy, Medical University of Vienna, Austria . Abstract (2 50 words) Background We aimed to quantify hepatic vessel volumes across chronic liver disease stages and healthy controls using deep learning - based magnetic resonance imaging ( MRI) analysis, and assess correlations with biomarkers for liver (dys)function and fibrosis/portal hypertension. Methods We assessed retrospectively healthy controls, non - advanced and advanced chronic liver disease (ACLD) patients using a 3D U - Net model for hepatic vessel segmentation on portal venous phase gadoxetic acid - enhanced 3 - T MRI. Total (TVVR), hepatic (HVVR), and intrahepatic portal vein - to - volume ratios (PVVR) were compared between groups and c orrelat ed with: a lbumin - b ilirubin [ ALBI ] and "m odel for e nd - s tage l iver d isease - s odium " [ MELD - Na ] s core) and fibrosis/portal hypertension (Fibrosis - 4 [ FIB - 4 ] Score, liver stiffness measurement [ LSM ], hepatic venous pressure gradient [ HVPG ], platelet count [ PLT ], and spleen volume. Results We included 197 subjects, aged 54.9 13.8 years (mean standard deviation), 111 males ( 56 .3 TVVR and HVVR were highest in controls (3.9; 2.1), intermediate in non - ACLD (2.8; 1.7), and lowest in ACLD patients (2.3; 1.0) ( p 0. 001) . PVVR was reduced in both non - ACLD and ACLD patients (both 1.2) compared to controls (1.7) ( p 0. 001), but showed no difference between CLD groups ( p = 0.999) . TVVR and PVVR showed similar but weaker correlations. Conclusion s Deep learning - based hepatic vessel volumetry demonstrate d differences between healthy liver and chronic liver disease stages and shows correlations with established markers of disease severity. Relevance s tatement Hepatic vessel volumetry demonstrates differences between healthy liver and chronic liver disease stages, potentially serving as a non - invasive imaging biomarker.


Tighter Value-Function Approximations for POMDPs

arXiv.org Artificial Intelligence

Solving partially observable Markov decision processes (POMDPs) typically requires reasoning about the values of exponentially many state beliefs. Towards practical performance, state-of-the-art solvers use value bounds to guide this reasoning. However, sound upper value bounds are often computationally expensive to compute, and there is a tradeoff between the tightness of such bounds and their computational cost. This paper introduces new and provably tighter upper value bounds than the commonly used fast informed bound. Our empirical evaluation shows that, despite their additional computational overhead, the new upper bounds accelerate state-of-the-art POMDP solvers on a wide range of benchmarks.


Large Language Models are Few-Shot Health Learners

arXiv.org Artificial Intelligence

Large language models (LLMs) can capture rich representations of concepts that are useful for real-world tasks. However, language alone is limited. While existing LLMs excel at text-based inferences, health applications require that models be grounded in numerical data (e.g., vital signs, laboratory values in clinical domains; steps, movement in the wellness domain) that is not easily or readily expressed as text in existing training corpus. We demonstrate that with only few-shot tuning, a large language model is capable of grounding various physiological and behavioral time-series data and making meaningful inferences on numerous health tasks for both clinical and wellness contexts. Using data from wearable and medical sensor recordings, we evaluate these capabilities on the tasks of cardiac signal analysis, physical activity recognition, metabolic calculation (e.g., calories burned), and estimation of stress reports and mental health screeners.


Implementing Dynamic Programming in Computability Logic Web

arXiv.org Artificial Intelligence

We present a novel definition of an algorithm and its corresponding algorithm language called CoLweb. The merit of CoLweb [1] is that it makes algorithm design so versatile. That is, it forces us to a high-level, proof-carrying, distributed-style approach to algorithm design for both non-distributed computing and distributed one. We argue that this approach simplifies algorithm design. In addition, it unifies other approaches including recursive logical/functional algorithms, imperative algorithms, object-oriented imperative algorithms, neural-nets, interaction nets, proof-carrying code, etc. As an application, we refine Horn clause definitions into two kinds: blind-univerally-quantified (BUQ) ones and parallel-universally-quantified (PUQ) ones. BUQ definitions corresponds to the traditional ones such as those in Prolog where knowledgebase is $not$ expanding and its proof procedure is based on the backward chaining. On the other hand, in PUQ definitions, knowledgebase is $expanding$ and its proof procedure leads to forward chaining and {\it automatic memoization}.


A category theoretical argument for causal inference

arXiv.org Artificial Intelligence

The goal of this paper is to design a causal inference method accounting for complex interactions between causal factors. The proposed method relies on a category theoretical reformulation of the definitions of dependent variables, independent variables and latent variables in terms of products and arrows in the category of unlabeled partitions. Throughout the paper, we demonstrate how the proposed method accounts for possible hidden variables, such as environmental variables or noise, and how it can be interpreted statistically in terms of $p$-values. This interpretation, from category theory to statistics, is implemented through a collection of propositions highlighting the functorial properties of ANOVA. We use these properties in combination with our category theoretical framework to provide solutions to causal inference problems with both sound algebraic and statistical properties. As an application, we show how the proposed method can be used to design a combinatorial genome-wide association algorithm for the field of genetics.


Grid Pathfinding on the 2 k Neighborhoods

AAAI Conferences

Grid pathfinding, an old AI problem, is central for the development of navigation systems for autonomous agents. A surprising fact about the vast literature on this problem is that very limited neighborhoods have been studied. Indeed, only the 4- and 8-neighborhoods are usually considered, and rarely the 16-neighborhood. This paper describes three contributions that enable the construction of effective grid path planners for extended 2 k -neighborhoods. First, we provide a simple recursive definition of the 2 k -neighborhood in terms of the 2 k –1 -neighborhood. Second, we derive distance functions, for any k >1, which allow us to propose admissible heurisitics which are perfect for obstacle-free grids. Third, we describe a canonical ordering which allows us to implement a version of A* whose performance scales well when increasing k . Our empirical evaluation shows that the heuristics we propose are superior to the Euclidean distance (ED) when regular A* is used. For grids beyond 64 the overhead of computing the heuristic yields decreased time performance compared to the ED. We found also that a configuration of our A*-based implementation, without canonical orders, is competitive with the "any-angle" path planner Theta$^*$ both in terms of solution quality and runtime.