A data-driven framework for identifying patient subgroups on which an AI/machine learning model may underperform.

A fundamental goal of evaluating the performance of a clinical model is to ensure it performs well across a diverse intended patient population. A primary challenge is that the data used in model development and testing often consist of many overlapping, heterogeneous patient subgroups that may not be explicitly defined or labeled. While a model's average performance on a dataset may be high, the model can have significantly lower performance for certain subgroups, which may be hard to detect.

Real-World Performance of Large Vessel Occlusion Artificial Intelligence-Based Computer-Aided Triage and Notification Algorithms-What the Stroke Team Needs to Know.

Purpose: To evaluate the real-world performance of two FDA-approved artificial intelligence (AI)-based computer-aided triage and notification (CADt) detection devices and compare them with the manufacturer-reported performance testing in the instructions for use.

Materials And Methods: Clinical performance of two FDA-cleared CADt large-vessel occlusion (LVO) devices was retrospectively evaluated at two separate stroke centers. Consecutive "code stroke" CT angiography examinations were included and assessed for patient demographics, scanner manufacturer, presence or absence of CADt result, CADt result, and LVO in the internal carotid artery (ICA), horizontal middle cerebral artery (MCA) segment (M1), Sylvian MCA segments after the bifurcation (M2), precommunicating part of cerebral artery, postcommunicating part of the cerebral artery, vertebral artery, basilar artery vessel segments.

Kaposiform lymphangiomatosis presenting with a Group A pericardial effusion.

A 4-year-old child was transferred to the paediatric intensive care unit with acute respiratory failure following 4 days of fever, nausea and vomiting. Chest X-ray on admission had an enlarged cardiac silhouette and transthoracic echo confirmed a large pericardial effusion. An emergent pericardiocentesis was performed at bedside which drained nearly 1000 mL of purulent fluid.

Does aging have an impact on hemoglobin? Study in elderly population at rural teaching hospital.

Background: The prevalence of anemia increases with age. Some serious underlying conditions may lead to anemia in the old age. The present study was undertaken to detect and do morphological typing of anemia and further delineate etiological factors in elderly patients.

Wearable technologies for active living and rehabilitation: Current research challenges and future opportunities.

This paper presents some recent developments in the field of wearable sensors and systems that are relevant to rehabilitation and provides examples of systems with evidence supporting their effectiveness for rehabilitation. A discussion of current challenges and future developments for selected systems is followed by suggestions for future directions needed to advance towards wider deployment of wearable sensors and systems for rehabilitation.

Developing international open science collaborations: Funder reflections on the Open Science Prize.

The Open Science Prize was established with the following objectives: first, to encourage the crowdsourcing of open data to make breakthroughs that are of biomedical significance; second, to illustrate that funders can indeed work together when scientific interests are aligned; and finally, to encourage international collaboration between investigators with the intent of achieving important innovations that would not be possible otherwise. The process for running the competition and the successes and challenges that arose are presented.

The National Institutes of Health Affordable Cancer Technologies Program: Improving Access to Resource-Appropriate Technologies for Cancer Detection, Diagnosis, Monitoring, and Treatment in Low- and Middle-Income Countries.

Point-of-care (POC) technologies have proved valuable in cancer detection, diagnosis, monitoring, and treatment in the developed world, and have shown promise in low-and-middle-income countries (LMIC) as well. Despite this promise, the unique design constraints presented in low-resource settings, coupled with the variety of country-specific regulatory and institutional dynamics, have made it difficult for investigators to translate successful POC cancer interventions to the LMIC markets. In response to this need, the National Cancer Institute has partnered with the National Institute of Biomedical Imaging and Bioengineering to create the National Institutes of Health Affordable Cancer Technologies (ACTs) program.

Workshop on using natural language processing applications for enhancing clinical decision making: an executive summary.

In April 2012, the National Institutes of Health organized a two-day workshop entitled 'Natural Language Processing: State of the Art, Future Directions and Applications for Enhancing Clinical Decision-Making' (NLP-CDS). This report is a summary of the discussions during the second day of the workshop. Collectively, the workshop presenters and participants emphasized the need for unstructured clinical notes to be included in the decision making workflow and the need for individualized longitudinal data tracking.

Assessment of cardiac motion effects on the fiber architecture of the human heart in vivo.

The use of diffusion tensor imaging (DTI) for studying the human heart in vivo is very challenging due to cardiac motion. This paper assesses the effects of cardiac motion on the human myocardial fiber architecture. To this end, a model for analyzing the effects of cardiac motion on signal intensity is presented.

In vivo cardiac diffusion-weighted magnetic resonance imaging: quantification of normal perfusion and diffusion coefficients with intravoxel incoherent motion imaging.

Objectives: Diffusion-weighted imaging (DWI) and the introduction of the intravoxel incoherent motion (IVIM) model have provided a unique method for evaluating perfusion and diffusion within a tissue without the need for a contrast agent. Despite its relevance, cardiac DWI has thus far been limited by low b values because of signal loss induced by physiological motion. The goal of this study was to develop a methodology for estimating IVIM parameters of in vivo cardiac magnetic resonance imaging using an efficient DWI acquisition framework.

Coronary artery wall imaging in mice using osmium tetroxide and micro-computed tomography (micro-CT).

The high spatial resolution of micro-computed tomography (micro-CT) is ideal for 3D imaging of coronary arteries in intact mouse heart specimens. Previously, micro-CT of mouse heart specimens utilized intravascular contrast agents that hardened within the vessel lumen and allowed a vascular cast to be made. However, for mouse coronary artery disease models, it is highly desirable to image coronary artery walls and highlight plaques.

3 Tesla turbo-FLASH magnetic resonance imaging of deglutition.

Objectives/hypothesis: In this article we describe a methodology for obtaining high-quality dynamic magnetic resonance imaging (MRI) sequences of the swallow sequence in healthy volunteers. The study includes comparison to previous work done in our lab using a 1.5 Tesla (T) magnet.

Interpretation of dark-field contrast and particle-size selectivity in grating interferometers.

In grating-based x-ray phase sensitive imaging, dark-field contrast refers to the extinction of the interference fringes due to small-angle scattering. For configurations where the sample is placed before the beamsplitter grating, the dark-field contrast has been quantified with theoretical wave propagation models. Yet when the grating is placed before the sample, the dark-field contrast has only been modeled in the geometric optics regime.

Low b-value diffusion-weighted cardiac magnetic resonance imaging: initial results in humans using an optimal time-window imaging approach.

Objectives: Diffusion-weighted imaging (DWI) using low b-values permits imaging of intravoxel incoherent motion in tissues. However, low b-value DWI of the human heart has been considered too challenging because of additional signal loss due to physiological motion, which reduces both signal intensity and the signal-to-noise ratio (SNR). We address these signal loss concerns by analyzing cardiac motion during a heartbeat to determine the time-window during which cardiac bulk motion is minimal.

Atropine-induced polymorphic ventricular tachycardia: a rare and bygone occurrence revisited.

Atropine is commonly a used pre anesthetic medication. A 22-year-old female with history of unexplained recurrent syncope during electrophysiology developed inducible ventricular arrhythmias when 0.5 mg of atropine was injected intravenously to improve this Wenckebach.

Real-time myocardial segmentation using coupled active geometric functions.

Myocardial segmentation is essential for quantitative evaluation of cardiac functional images. As imaging techniques advance, 3D and 4D image data have become available. These data can provide clinically important cardiac dynamic information at high spatial or temporal resolution.

Extrinsic multiecho phase-contrast SSFP: evaluation on cardiac output measurements.

Multiecho phase-contrast steady-state free precession (PC-SSFP) is a recently introduced sequence for flow quantification. In this multiecho approach, a phase reference and a velocity-encoded readout were acquired at different echo times after a single excitation. In this study, the sequence is validated in vitro for stationary flow.

A rare and unusual cause of PSA (prostate-specific antigen) elevation: sarcoidosis of the prostate.

Sarcoidosis and prostate cancer are 2 separate conditions that are more prevalent among the African American population. However, sarcoidosis of the prostate is a very rare clinical entity. Its association with prostate cancer is described in clinical case series.

Theory, technique, and practice of magnetic resonance angiography.

Magnetic resonance angiography (MRA) is now a widely accepted technique used to characterize vascular pathology such as stenosis, dissection, fistula, and aneurysms. Magnetic resonance techniques are increasingly driving clinical decision making by vascular physicians. The physics behind MRA can contribute to the general understanding and interpretation of the anatomic images.

Phase contrast using multiecho steady-state free precession.

Conventional phase-contrast (PC) MRI is limited in the temporal resolution (typically 50 ms) that can be achieved, due to the need to implement bipolar velocity encoding gradients. PC using steady-state free precession (SSFP) has recently been developed to acquire PC data at higher rates without sacrificing contrast-to-noise ratio (CNR). This work presents two multiecho SSFP PC implementations that can be used to increase the time efficiency of PCSSFP.

Advances in MRI tagging techniques for determining regional myocardial strain.

MRI of the heart with magnetization tagging provides a potentially useful new way to assess cardiac mechanical function, through revealing the local motion of otherwise indistinguishable portions of the heart wall. Although still an evolving area, tagged cardiac MRI is already able to provide novel quantitative information on cardiac function. Exploiting this potential requires developing tailored methods for both imaging and image analysis.

High-resolution imaging reveals a limit in spatial resolution of blood flow measurements by microspheres.

Density of 15-microm microspheres after left atrial application is the standard measure of regional perfusion. In the heart, substantial differences in microsphere density are seen at spatial resolutions <5 ml, implying perfusion heterogeneity. Microsphere deposition imaging permits a superior evaluation of the distribution pattern.