Faculty Bibliography
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211
Proceedings of SPIE (The International Society for Optical Engineering). 2016:9788.DOI: 10.1117/12.2216240
Analysis of cardiac interventricular Septum Motion in different respiratory States [Meeting Abstract]
The interaction between the left and right heart ventricles (LV and RV) depends on load and pressure conditions that are affected by cardiac contraction and respiration cycles. A novel MRI sequence, XD-GRASP, allows the acquisition of multi-dimensional, respiration-sorted and cardiac-synchronized free-breathing image data. In these data, effects of the cardiac and respiratory cycles on the LV/RV interaction can be observed independently. To enable the analysis of such data, we developed a semi-automatic exploration workflow. After tracking a cross-sectional line positioned over the heart, over all motion states, the septum and heart wall border locations are detected by analyzing the grey-value profile under the lines. These data are used to quantify septum motion, both in absolute units and as a fraction of the heart size, to compare values for different subjects. In addition to conventional visualization techniques, we used color maps for intuitive exploration of the variable values for this multi-dimensional data set. We acquired short-axis image data of nine healthy volunteers, to analyze the position and the motion of the interventricular septum in different breathing states and different cardiac cycle phases. The results indicate a consistent range of normal septum motion values, and also suggest that respiratory phase-dependent septum motion is greatest near end-diastolic phases. These new methods are a promising tool to assess LV/RV ventricle interaction and the effects of respiration on this interaction.
ISI:000378223800029
ISSN: 0277-786x
CID: 2228162
Cardiac function analysis with cardiorespiratory-synchronized CMR [Meeting Abstract]
Background: Conventional cine MRI provides data on the variation of cardiac dimensions across the cardiac cycle; cardiac function analysis primarily focuses on the difference between end-diastolic (ED) and endsystolic (ES) dimensions of the left and right ventricles (LV and RV). With cardiorespiratory-synchronized (CRS) CMR, there is an additional effective dimension of information available, related to the effect of the respiratory cycle phase on cardiac dimensions. However, there are currently no established ways to analyze this potentially useful additional physiological data. We have developed a set of tools for the functional analysis of CRS CMR, particularly for the study of the respiratory effects on LV-RV interaction, and derived some initial normative values for the results. Methods: We have developed a set of interactive CMR function analysis programs. Images from CRS CMR are organized in a two-dimensional matrix, sorted by cardiac and respiratory cycle phases. The user can interactively position an analysis line across the ventricles in a representative image; this line can then be automatically tracked across the other cardiac and respiratory phases. The intensity profile along the line is then used to automatically track the corresponding positions of the edges of the LV and RV free walls and the interventricular septum (IVS). A variety of absolute and normalized variables can be derived from these varying positions, including ED and ES dimensions, and displayed as functional images over the cardiac and respiratory cycle dimensions. CRS CMR was performed with a sparsity-based method (XD-GRASP), using continuous acquisition of radial k-space samples with golden-angle increments and retrospective cardiac and respiratory phase sorting in reconstruction. An initial set of CRS CMR data from 9 normal subjects (age 28.33 +/- 5.85) was analyzed, as well as from 3 patients (age 40 +/- 9.66, one with HCM). Results: On visual inspection of the images, it is apparent that there is a clear shift in the relative position of the IVS over the respiratory cycle, to the left in inspiration and to the right in expiration, reflecting the LV-RV interaction; this is much more prominent near ED than ES. For the normal subjects, in midlevel short-axis views, the respiratory-related absolute shift in IVS position was 1.07-3.23 mm at ED and 0.69-2.14 mm at ES; corresponding values normalized to ED dimension were 2.65-7.08 pp and 1.99-5.18 pp. The ED-ES difference for the normalized shift ranges was -1.9-4.35 pp (median 1.35, first quartile 0.68). For the HCM patient, the difference between the shift ranges was 0.79 pp. Linear regression when plotting NCD against NEDD (reflecting the Frank-Starling relationship and giving an estimate of contractility) was 0.68 +/- 0.11 in the normal subjects. Conclusions: Novel physiologic data on LV-RV interaction can be derived from CRS CMR; this seems to show consistent ranges in normal subjects, and may provide useful information on disease-related changes in cardiac function. (Figure Presented)
EMBASE:72183348
ISSN: 1097-6647
CID: 1950592
Diagnostic Accuracy of Cardiac Magnetic Resonance Imaging in the Evaluation of Newly Diagnosed Heart Failure With Reduced Left Ventricular Ejection Fraction
The aim of this study was to determine the diagnostic value of cardiac magnetic resonance (CMR) imaging with late gadolinium enhancement (LGE), cine imaging, and resting first-pass perfusion (FPP) in the evaluation for ischemic (IC) versus nonischemic (NIC) cardiomyopathy in new-onset heart failure with reduced (
PMCID:4567940
PMID: 26251006
ISSN: 1879-1913
CID: 1709282
Clearance systems in the brain-implications for Alzheimer disease
Accumulation of toxic protein aggregates-amyloid-beta (Abeta) plaques and hyperphosphorylated tau tangles-is the pathological hallmark of Alzheimer disease (AD). Abeta accumulation has been hypothesized to result from an imbalance between Abeta production and clearance; indeed, Abeta clearance seems to be impaired in both early and late forms of AD. To develop efficient strategies to slow down or halt AD, it is critical to understand how Abeta is cleared from the brain. Extracellular Abeta deposits can be removed from the brain by various clearance systems, most importantly, transport across the blood-brain barrier. Findings from the past few years suggest that astroglial-mediated interstitial fluid (ISF) bulk flow, known as the glymphatic system, might contribute to a larger portion of extracellular Abeta (eAbeta) clearance than previously thought. The meningeal lymphatic vessels, discovered in 2015, might provide another clearance route. Because these clearance systems act together to drive eAbeta from the brain, any alteration to their function could contribute to AD. An understanding of Abeta clearance might provide strategies to reduce excess Abeta deposits and delay, or even prevent, disease onset. In this Review, we describe the clearance systems of the brain as they relate to proteins implicated in AD pathology, with the main focus on Abeta.
PMCID:4694579
PMID: 26195256
ISSN: 1759-4766
CID: 1683822
Preliminary Assessment of Tricuspid Valve Annular Velocity Parameters by Cardiac Magnetic Resonance Imaging in Adults with a Volume-Overloaded Right Ventricle: Comparison of Unrepaired Atrial Septal Defect and Repaired Tetralogy of Fallot
The aim is to compare tricuspid valve (TV) atrioventricular junction (AVJ) annular motion parameters in unrepaired atrial septal defect (ASD) and repaired Tetralogy of Fallot (TOF) by cardiac magnetic resonance (CMR) imaging. We retrospectively reviewed CMR studies performed between November 2007 and November 2013 in patients 16-45 years of age with unrepaired ASD (with or without partial anomalous pulmonary venous return) and with repaired TOF, who had previous infundibulotomy, but have not undergone pulmonary valve replacement. Longitudinal motion of lateral TV in four-chamber view cine image was tracked through the cardiac cycle with custom software. Twenty TOF patients and 12 ASD patients were included, and values were compared with 80 controls. Right ventricular end-diastolic volume index and right ventricular end-systolic volume index were similar in the ASD and TOF groups and were significantly higher in both groups than in controls. Maximum displacement of the TV in systole, velocity at half-maximal displacement during systole, and velocity at half-maximal displacement during early diastole were all significantly lower in the TOF group than the ASD group [1.39 +/- 0.47 vs. 2.21 +/- 0.46 (cm, p < 0.01), 5.9 +/- 2.1 vs. 10.1 +/- 2.3 (cm/s, p < 0.01), and 7.7 +/- 2.6 vs. 10.9 +/- 3.1 (cm/s, p < 0.05)]. TOF patients have diminished early diastolic TV AVJ velocity compared to patients with an unrepaired ASD, despite similar RV volumes. This observation could suggest diastolic dysfunction or cardiac mechanics unique to the postoperative, volume-overloaded right ventricle in patients with repaired TOF.
PMID: 25835201
ISSN: 1432-1971
CID: 1519622
Prenatal Diagnosis of a Persistent Fifth Aortic Arch, Pulmonary-to-Systemic type: An Unusual Association with Evolving Aortic Coarctation
Persistent fifth arch (PFA) is a rare anomaly that is often underdiagnosed and missed. Different PFA types that have been reported in the literature are systemic-to-systemic type (most common), systemic-to-pulmonary artery (PA), and PA-to-systemic types. The designations of systemic-to-PA or PA-to-systemic are based on if the PFA is a source of PA or systemic blood flow, respectively, in the setting of critical proximal obstruction (pulmonary atresia or aortic atresia). This case describes an unusual PFA, which connects the distal PA to distal ascending aorta; however, it is not associated with critical proximal obstruction, and while it appeared to be an incidental finding in early gestation, progressive serial distal obstruction of the left fourth arch was seen to develop. This case highlights that prenatal diagnosis of PFA is possible and that once a diagnosis is made, serial fetal echocardiograms should be performed to evaluate for evolving lesions.
PMID: 25418608
ISSN: 0742-2822
CID: 1359402
Meshless Deformable Models for 3D Cardiac Motion and Strain Analysis from Tagged MRI
Tagged Meganetic Resonance Image (TMRI) provides a direct and noninvasive way to visualize the in-wall deformation of the myocardium. Due to the through-plane motion, the tracking of 3D trajectories of the material points and the computation of 3D strain field call for the nessicity of building 3D cardiac deformable models. The intersections of three stacks of orthogonal tagging planes are material points in the myocardium. With these intersections as control points, 3D motion can be reconstructed with a novel meshless deformable model. Volumetric meshless deformable models describe an object as point cloud inside the object boundary and the coordinate of each point can be written in parametric functions. A generic heart mesh is registered on the tagged MRI with polar decomposition. A 3D meshless deformable model is generated and deformed with MR image tagging lines. Volumetric meshless deformable models are deformed by calculating the dynamics function and minimizing the local Laplacian coordinates. The similarity transformation of each point is computed by assuming its neighboring points are making the same transformation. The deformation is computed iteratively until the control points match the target positions in the consecutive image frame. The 3D strain field is computed from the 3D displacement field with Moving Least Squares (MLS). We demonstrate that meshless deformable models outperformed the finite element method (FEM) and the spline method with a numerical phantom. Meshless deformable models can track the trajectory of any material point in the myocardium and compute the 3D strain field of any particular area. The experimental results on in vivo healthy and patient heart MRI show that the meshless deformable model can fully recover the myocardium motion in three dimension.
PMCID:4876045
PMID: 25157446
ISSN: 0730-725x
CID: 1162302
Assessment of Septal Motion Abnormalities in Left Bundle Branch Block Patients Using Computer Simulations
New York : Springer Verlag, 2015
pp. 40-47
ISBN: 9783319203089
CID: 1701942
Giant Cell Myocarditis: Not Always a Presentation of Cardiogenic Shock
Giant cell myocarditis is a rare and often fatal disease. The most obvious presentation often described in the literature is one of rapid hemodynamic deterioration due to cardiogenic shock necessitating urgent consideration of mechanical circulatory support and heart transplantation. We present the case of a 60-year-old man whose initial presentation was consistent with myopericarditis but who went on to develop a rapid decline in left ventricular systolic function without overt hemodynamic compromise or dramatic symptomatology. Giant cell myocarditis was confirmed via endomyocardial biopsy. Combined immunosuppression with corticosteroids and calcineurin inhibitor resulted in resolution of symptoms and sustained recovery of left ventricular function one year later. Our case highlights that giant cell myocarditis does not always present with cardiogenic shock and should be considered in the evaluation of new onset cardiomyopathy of uncertain etiology as a timely diagnosis has distinct clinical implications on management and prognosis.
PMCID:4519529
PMID: 26257963
ISSN: 2090-6404
CID: 1720932
Proceedings of SPIE (The International Society for Optical Engineering). 2015:9417.DOI: 10.1117/12.2085033
The rapid imaging renaissance: sparser samples, denser dimensions, and glimmerings of a grand unified tomography [Meeting Abstract]
The task of imaging is to gather spatiotemporal information which can be organized into a coherent map. Tomographic imaging in particular involves the use of multiple projections, or other interactions of a probe (light, sound, etc.) with a body, in order to determine cross-sectional information. Though the probes and the corresponding imaging modalities may vary, and though the methodology of particular imaging approaches is in constant ferment, the conceptual underpinnings of tomographic imaging have in many ways remained fixed for many decades. Recent advances in applied mathematics, however, have begun to roil this intellectual landscape. The advent of compressed sensing, anticipated in various algorithms dating back many years but unleashed in full theoretical force in the last decade, has changed the way imagers have begun to think about data acquisition and image reconstruction. The power of incoherent sampling and sparsity-enforcing reconstruction has been demonstrated in various contexts and, when combined with other modern fast imaging techniques, has enabled unprecedented increases in imaging efficiency. Perhaps more importantly, however, such approaches have spurred a shift in perspective, prompting us to focus less on nominal data sufficiency than on information content. Beginning with examples from MRI, then proceeding through selected other modalities such as CT and PET, as well as multimodality combinations, this paper explores the potential of newly evolving acquisition and reconstruction paradigms to change the way we do imaging in the lab and in the clinic.
ISI:000355665600014
ISSN: 0277-786x
CID: 2061802
