Automated Assessment of T2-Weighted MRI to Differentiate Malignant and Benign Primary Solid Liver Lesions in Noncirrhotic Livers Using Radiomics

Rationale and Objectives: Distinguishing malignant from benign liver lesions based on magnetic resonance imaging (MRI) is an important but often challenging task, especially in noncirrhotic livers. We developed and externally validated a radiomics model to quantitatively assess T2-weighted MRI to distinguish the most common malignant and benign primary solid liver lesions in noncirrhotic livers. Materials and Methods: Data sets were retrospectively collected from three tertiary referral centers (A, B, and C) between 2002 and 2018. Patients with malignant (hepatocellular carcinoma and intrahepatic cholangiocarcinoma) and benign (hepatocellular adenoma and focal nodular hyperplasia) lesions were included. A radiomics model based on T2-weighted MRI was developed in data set A using a combination of machine learning approaches. The model was internally evaluated on data set A through cross-validation, externally validated on data sets B and C, and compared to visual scoring of two experienced abdominal radiologists on data set C. Results: The overall data set included 486 patients (A: 187, B: 98, and C: 201). The radiomics model had a mean area under the curve (AUC) of 0.78 upon internal validation on data set A and a similar AUC in external validation (B: 0.74 and C: 0.76). In data set C, the two radiologists showed moderate agreement (Cohen's κ: 0.61) and achieved AUCs of 0.86 and 0.82. Conclusion: Our T2-weighted MRI radiomics model shows potential for distinguishing malignant from benign primary solid liver lesions. External validation indicated that the model is generalizable despite substantial MRI acquisition protocol differences. Pending further optimization and generalization, this model may aid radiologists in improving the diagnostic workup of patients with liver lesions.</p

A modified Lowe-Andersen thermostat for a hard sphere fluid

In order to model the thermal interaction between two hard sphere particles, we propose a small modification of the Lowe-Andersen thermostat, a well-known numerical thermostat that acts on selected pairs of particles. The simulation procedure presented here is local, easy to implement and computationally inexpensive while perturbing the natural dynamics of the system in a minimal fashion

Erratum to: A modified Lowe-Andersen thermostat for a hard sphere fluid

There are two small errors at the beginning of sect. 2 which have been corrected in the present erratum

Advantages of the Rayleigh–Lowe–Andersen thermostat in soft sphere molecular dynamics simulations

The Rayleigh–Lowe–Andersen thermostat is a momentum-conserving, Galilean-invariant analogue of the Andersen thermostat, like the original (Maxwellian) Lowe–Andersen thermostat. However, the Rayleigh–Lowe–Andersen thermostat remains local even if the fluid density becomes low. By using a minimized thermostat interaction radius we show with a molecular dynamics simulation that the Rayleigh–Lowe–Andersen thermostat affects the natural dynamics of a low-density Lennard–Jones fluid in a minimal fashion. We also show that it is no longer necessary to consider a separate simulation just to determine the optimal value of the thermostat interaction radius. Instead, this value is computed directly during the main simulation run. Because the Rayleigh–Lowe–Andersen thermostat can be combined with the velocity Verlet integration scheme, we expect a widespread applicability of the thermal mechanism presented here