Measurement of transcranial Doppler insonation angles from three-dimensional reconstructions of CT angiography scans.

Blood velocities measured by Transcranial Doppler (TCD) are dependent on the angle between the incident ultrasound beam and the direction of blood flow (known as the Doppler angle). However, when TCD examinations are performed without imaging the Doppler angle for each vessel segment is not known. We have measured Doppler angles in the basal cerebral arteries examined with TCD using three-dimensional (3D) vessel models generated from computed tomography angiography (CTA) scans.

Numerical Modeling of Flow in the Cerebral Vasculature: Understanding Changes in Collateral Flow Directions in the Circle of Willis for a Cohort of Vasospasm Patients Through Image-Based Computational Fluid Dynamics.

The Circle of Willis (CoW) is a ring-like network of blood vessels that perfuses the brain. Flow in the collateral pathways that connect major arterial inputs in the CoW change dynamically in response to vessel narrowing or occlusion. Vasospasm is an involuntary constriction of blood vessels following subarachnoid hemorrhage (SAH), which can lead to stroke.

A Novel Patient-Specific Computational Fluid Dynamics Study of the Activation of Primary Collateral Pathways in the Circle of Willis During Vasospasm.

The Circle of Willis (CoW) is a redundant network of blood vessels that perfuses the brain. The ringlike anatomy mitigates the negative effects of stroke by activating collateral pathways that help maintain physiological perfusion. Previous studies have investigated the activation of these pathways during embolic stroke and internal carotid artery occlusion.

Transesophageal echocardiography simulation: A review of current technology.

Transesophageal echocardiography (TEE) has experienced tremendous increase in interest and demand alongside the rapid growth of transcatheter structural cardiac interventions. TEE instruction prolongs the procedure, increasing the risk of probe malfunction from overheating and patient complications from prolonged sedation. Echocardiographic simulation programs have been developed to hone the procedural skills of novice operators in a time-unrestricted, low-pressure environment before they perform TEEs on real patients.

Focused cardiac ultrasound training in medical students: Using an independent, simulator-based curriculum to objectively measure skill acquisition and learning curve.

Background: Using simulators built and validated at the University of Washington (UW), the study sought to test whether medical students can learn the basic skills of focused cardiac ultrasound (FoCUS) from an individually paced, simulator-based curriculum, how skills improve, and the rate at which these skills are acquired.

Methods: The curriculum presented didactic material interspersed with hands-on practice. Psychomotor skill was measured by the angle error of the acquired image view plane relative to the correct image view plane.

Analysis of Factors Influencing Accuracy of Volume Flow Measurement in Dialysis Access Fistulas Based on Duplex Ultrasound Simulation.

Objective: We developed a duplex ultrasound simulator and used it to assess accuracy of volume flow measurements in dialysis access fistula (DAF) models.

Methods: The simulator consists of a mannequin, computer, and mock transducer. Each case is built from a patient's B-mode images that are used to create a 3-dimensional surface model of the DAF.

Formative Assessment of Performance in Diagnostic Ultrasound Using Simulation and Quantitative and Objective Metrics.

Background: We developed simulator-based tools for assessing provider competence in transthoracic echocardiography (TTE) and vascular duplex scanning.

Methods: Psychomotor (technical) skill in TTE image acquisition was calculated from the deviation angle of an acquired image from the anatomically correct view. We applied this metric for formative assessment to give feedback to learners and evaluate curricula.

Integrating Scaffolding and Deliberate Practice Into Focused Cardiac Ultrasound Training: A Simulator Curriculum.

Introduction: Focused cardiac ultrasound (FoCUS) is widely used for the point-of-care evaluation of basic cardiac pathology, and there is a need for efficient and consistent training in this modality. We designed a simulator-based FoCUS curriculum that integrates instructional scaffolding and deliberate practice to create a directed, self-regulated learning experience for novices. The goal of this strategy was to guide the novice's learning efforts more efficiently and moderate cognitive load while retaining the benefits of independent learning.

Test of simulator-based assessment of psychomotor skill in transthoracic echo.

Background: We developed a transthoracic echo simulator that measures technical skill in image acquisition in terms of the deviation angle between an acquired image and the anatomically correct plane for that view. We studied whether this metric reflects the clinical experience of providers.

Methods: Attendees at an echo course or at the annual meeting of the Swedish Heart Association were invited to test themselves on the simulator by scanning a mannequin and acquiring four views in 15 min: parasternal long axis (pLAX) in patient 1, apical four chamber and apical long axis (aLAX) in patient 2 and pLAX in patient 3.

Simulation for competency assessment in vascular and cardiac ultrasound.

Healthcare providers who use peripheral vascular and cardiac ultrasound require specialized training to develop the technical and interpretive skills necessary to perform accurate diagnostic tests. Assessment of competence is a critical component of training that documents a learner's progress and is a requirement for competency-based medical education (CBME) as well as specialty certification or credentialing. The use of simulation for CBME in diagnostic ultrasound is particularly appealing since it incorporates both the psychomotor and cognitive domains while eliminating dependency on the availability of live patients with a range of pathology.

Comparison of systemic right ventricular function in transposition of the great arteries after atrial switch and congenitally corrected transposition of the great arteries.

In patients with transposition of the great arteries corrected by interatrial baffle (TGA) and those with congenitally corrected transposition of the great arteries (ccTGA) the right ventricle (RV) is subjected to systemic pressure and fails prematurely. Previous studies have demonstrated RV dysfunction may be more pronounced in patients with TGA. The present study sought to compare patients with TGA and ccTGA using three-dimensional (3D) techniques to comprehensively analyze the shape, volume, global and regional function in the systemic RV.

Quantitative Feedback Facilitates Acquisition of Skills in Focused Cardiac Ultrasound.

Introduction: With the development of portable, affordable ultrasound machines with good image quality, many physicians have adopted focused cardiac ultrasound (FoCUS). To facilitate acquisition of these skills, we developed a simulator-based, self-taught curriculum for FoCUS that provides immediate feedback for rapid performance improvement.

Methods: Twenty-two first-year residents participated in the study.

The shape and function of the left ventricle in Ebstein's anomaly.

Background: Left ventricular (LV) failure is common in Ebstein's anomaly, though remains poorly understood. We investigated whether shape deformity impacts LV function.

Methods: Three-dimensional models of the right ventricle (RV) and LV from 29 adult Ebstein's patients and nine normal subjects were generated from cardiac magnetic resonance image tracings.

The Transaxial Orientation Is Superior to Both the Short Axis and Horizontal Long Axis Orientations for Determining Right Ventricular Volume and Ejection Fraction Using Simpson's Method with Cardiac Magnetic Resonance.

We sought to determine which of the three orientations is the most reliable and accurate for quantifying right ventricular (RV) volume and ejection fraction (EF) by cardiac magnetic resonance using Simpson's method. We studied 20 patients using short axis (SA), transaxial (TA), and horizontal long axis (HLA) orientations. Three readers independently traced RV endocardial contours at end-diastole and end-systole for each orientation.

Echo simulator with novel training and competency testing tools.

We developed and validated an echo simulator with three novel tools that facilitate training and enable quantitative and objective measurement of psychomotor as well as cognitive skill. First, the trainee can see original patient images - not synthetic or simulated images - that morph in real time as the mock transducer is manipulated on the mannequin. Second, augmented reality is used for Visual Guidance, a tool that assists the trainee in scanning by displaying the target organ in 3-dimensions (3D) together with the location of the current view plane and the plane of the anatomically correct view.

Regional right ventricular wall motion in tetralogy of fallot: a three dimensional analysis.

We observed an abnormal contraction pattern in the right ventricle (RV) in postoperative tetralogy of Fallot (TOF) patients when measuring the regional contribution to global stroke volume (rSV) of 20 RV slices from apex to base. We compared the rSV method's performance with the centersurface method which offers greater flexibility in defining regions of interest. We reconstructed the RV in 3D from manually traced borders in 20 repaired TOF patients and nine normal subjects from cardiac magnetic resonance images.

Three-dimensional analysis of right ventricular shape and function in pulmonary hypertension.

Right ventricular (RV) failure is a key determinant of morbidity and mortality in pulmonary hypertension (PH). The present study aims to add to existing descriptions of RV structural and functional changes in PH through a comprehensive three-dimensional (3D) shape analysis. We performed 3D echocardiography on 53 subjects with PH and 19 normal subjects.

The shape and function of the right ventricle in Ebstein's anomaly.

Background: Ebstein's anomaly involves both the right ventricle (RV) and tricuspid valve.

Methods: The functional RV and tricuspid orifice were traced from magnetic resonance images in 29 adult Ebstein patients and 9 normal subjects and reconstructed for visualization and measurement of regional RV size, function, and shape at 20 cross sections, and inlet and outflow tract ejection fractions (EFs).

Results: The RV in Ebstein's had RV dilation (end diastolic volume index 179 ± 69 vs.

Comparison of Simpson's method and three-dimensional reconstruction for measurement of right ventricular volume in patients with complete or corrected transposition of the great arteries.

The right ventricular (RV) volume is commonly measured from magnetic resonance images using Simpson's method from the stack of short-axis images acquired for analysis of the left ventricle. We compared the RV volume measured using Simpson's method to the RV volume measured using 3-dimensional reconstruction and the piecewise smooth subdivision surface (PSSS) method. We studied 6 normal subjects and 18 patients whose right ventricles carried a systemic pressure load, 1/2 with dexto-transposition of the great arteries repaired with an atrial baffle and 1/2 with levo-transposition of the great arteries.

Significance of mechanical alterations in single ventricle patients on twisting and circumferential strain as determined by analysis of strain from gradient cine magnetic resonance imaging sequences.

Preliminary speckle-tracking echocardiographic studies show that patients with single ventricles (SVs) have significantly decreased twisting and dyssynchrony of twisting. This could be related to abnormal cardiac looping, which leads to hearts that lack helical fiber patterns. The aim of this study was to analyze gradient cine magnetic resonance imaging (MRI) using Velocity Vector Imaging to assess cardiac mechanics.

Accuracy of knowledge-based reconstruction for measurement of right ventricular volume and function in patients with tetralogy of Fallot.

We tested the accuracy and reproducibility of knowledge-based reconstruction (KBR) for measuring right ventricular (RV) volume and function. KBR enables rapid assessment of the right ventricle from sparse user input by referencing a database. KBR generates a 3-dimensional surface to fit points that the user enters at anatomic landmarks.

Expert visual guidance of ultrasound for telemedicine.

Expert visual guidance (EVG) is computer assistance that displays to the examiner how the image plane moves towards (or away from) a desired anatomical location as the ultrasound probe is manipulated over the patient's body. We tested whether EVG by a remote expert could assist inexperienced examiners in acquiring abdominal ultrasound images. The inexperienced examiners were 20 medical students, who were randomly assigned to verbal instruction alone (Group 1) or to EVG (Group 2).

Determination of right ventricular end systole by cardiovascular magnetic resonance imaging: a standard method of selection.

For reproducible measurements of right ventricular (RV) volume and function, it may be important to use a consistent method to identify end systole (ES). We determined whether a significant difference exists between RV volumes measured using varying criteria from previous studies to define the timing of ES. In three normal subjects and nine patients with congenital heart disease, we measured RV volume from 3D reconstructions generated from 12 short and long axis magnetic resonance images (MRI).