A Call for the Structured Physicist Report

Introduction: The field of diagnostic radiology continues to struggle with the clinical adoption of the structured interpretive report, with many radiologists preferring a semistructured, free-text dictation style to a more rigid, highly structured approach that some professional leaders have promoted [1]. Although structured reporting compliance in the radiologist community has been difficult to achieve, diagnostic radiologists have been thinking about and discussing this important issue for many years; it is also a part of the ACR’s Imaging 3.0_ campaign [2]. In the breast imaging community, the well-established BI-RADS_ recommendations produce a very structured report, with a discussion of interpretive findings culminating in a numeric BI-RADS score ranging from 0 to 6 [3]. Unlike some interpretive radiology reports, which can be ambiguous in terms of the next course of action, the BI-RADS scale is not only a diagnostic scale but also prescriptive of what the necessary follow-up should be

Generalization of Artificial Intelligence Models in Medical Imaging: A Case-Based Review

The discussions around Artificial Intelligence (AI) and medical imaging are centered around the success of deep learning algorithms. As new algorithms enter the market, it is important for practicing radiologists to understand the pitfalls of various AI algorithms. This entails having a basic understanding of how algorithms are developed, the kind of data they are trained on, and the settings in which they will be deployed. As with all new technologies, use of AI should be preceded by a fundamental understanding of the risks and benefits to those it is intended to help. This case-based review is intended to point out specific factors practicing radiologists who intend to use AI should consider

Adaptive Statistical Iterative Reconstruction-V for Lung Nodule Analysis

Introduction: Low-dose CT in lung cancer screening has demonstrated benefits in select patients. As the traditional filtered back projection (FBP) technique is limited by poor image quality, adaptive statistical iterative reconstruction-V (ASIR-V) algorithm has been developed to achieve higher image quality with processing efficiency. Objective: To investigate the impact of various CT scan parameters on the semi-automated measurement of lung nodules using a Computer Aided Detection (CAD) program. Methods: This IRB-exempt phantom experiment was conducted with a CT scanner capable of ASIR-V algorithm. Eight lung nodules sized 5-12 mm, of solid or ground glass type, were placed inside a multipurpose chest phantom with or without fat slabs. Voltage (kV), current (mA), and ASIR-V levels were varied, and series of CT images were produced. A CAD program semiautomatically analyzed the series and produced nodule diameters and volumes. Nodule measurement variance and the significance of variables were analyzed by one-way ANOVA and univariate regression. Results: Nodule diameter and type contributed to error in both diameter and volume measurements. Current also impacted diameter measurement error. ASIR-V, kV, and fat slabs did not contribute to nodule measurement systematic error. On regression analysis, error is negatively related to mA and solid nodules, but is positively related to nodule diameter or volume. Discussion: These results reinforce that nodule size, type, and mA have the highest influence on CAD software performance nodule quantification accuracy. ASIR-V and kV do not significantly alter the measurement error but, instead, maintain the accuracy of nodule evaluation while minimizing radiation dose

The Evolution of Cloud Cores and the Formation of Stars

For a number of starless cores, self-absorbed molecular line and column density observations have implied the presence of large-amplitude oscillations. We examine the consequences of these oscillations on the evolution of the cores and the interpretation of their observations. We find that the pulsation energy helps support the cores and that the dissipation of this energy can lead toward instability and star formation. In this picture, the core lifetimes are limited by the pulsation decay timescales, dominated by non-linear mode-mode coupling, and on the order of ~few x 10^5--10^6 yr. Notably, this is similar to what is required to explain the relatively low rate of conversion of cores into stars. For cores with large-amplitude oscillations, dust continuum observations may appear asymmetric or irregular. As a consequence, some of the cores that would be classified as supercritical may be dynamically stable when oscillations are taken into account. Thus, our investigation motivates a simple hydrodynamic picture, capable of reproducing many of the features of the progenitors of stars without the inclusion of additional physical processes, such as large-scale magnetic fields.Comment: 12 pages, 7 figures, submitted to Ap

Double Core Evolution X. Through the Envelope Ejection Phase

The evolution of binary systems consisting of an asymptotic giant branch star of mass equal to 3 M_sun or 5 M_sun, and a main sequence star of mass equal to 0.4 M_sun or 0.6 M_sun with orbital periods > 200 days has been followed from the onset through the late stages of the common envelope phase. Using a nested grid technique, the three-dimensional hydrodynamical simulations of an asymptotic giant branch star with radii approximately 1 A.U. indicate that a significant fraction of the envelope gas is unbound (about 31% and 23% for binaries of 3 M_sun and 0.4 M_sun, and 5 M_sun and 0.6 M_sun respectively) by the ends of the simulations, and that the efficiency of the mass ejection process is about 40%. While the original volume of the giant is virtually evacuated in the late stages, most of the envelope gas remains marginally bound on the grid. At the ends of our simulations, when the orbital decay timescale exceeds about 5 years, the giant core and companion orbit one another with a period of about 1 day (2.4 days for a binary involving a more evolved giant), although this is an upper limit to the final orbital period. For a binary of 5 M_sun and 0.4 M_sun, the common envelope may not be completely ejected.Comment: 34 pages, 16 figures, accepted to Ap