Faculty Bibliography

Patients with left bundle branch block (LBBB) can exhibit mechanical dyssynchrony which may contribute to heart failure; such patients may benefit from cardiac resynchronization treatment (CRT). While cardiac magnetic resonance imaging (CMR) has become a common part of heart failure work-up, CMR features of mechanical dyssynchrony in patients with LBBB have not been well characterized. This study aims to investigate the potential of CMR to characterize mechanical features of LBBB. CMR examinations from 43 patients with LBBB on their electrocardiogram, but without significant focal structural abnormalities, and from 43 age- and gender-matched normal controls were retrospectively reviewed. The following mechanical features of LBBB were evaluated: septal flash (SF), apical rocking (AR), delayed aortic valve opening measured relative to both end-diastole (AVOED) and pulmonic valve opening (AVOPVO), delayed left-ventricular (LV) free-wall contraction, and curvatures of the septum and LV free-wall. Septal displacement curves were also generated, using feature-tracking techniques. The echocardiographic findings of LBBB were also reviewed in those subjects for whom they were available. LBBB was significantly associated with the presence of SF and AR; within the LBBB group, 79 % had SF and 65 % had AR. Delayed AVOED, AVOPVO, and delayed LV free-wall contraction were significantly associated with LBBB. AVOED and AVOPVO positively correlated with QRS duration and negatively correlated with ejection fraction. Hearts with electrocardiographic evidence of LBBB showed lower septal-to-LV free-wall curvature ratios at end-diastole compared to normal controls. CMR can be used to identify and evaluate mechanical dyssynchrony in patients with LBBB. None of the normal controls showed the mechanical features associated with LBBB. Moreover, not all patients with LBBB showed the same degree of mechanical dyssynchrony, which could have implications for CRT.

Heart disease is a worldwide public health problem; assessment of cardiac function is an important part of the diagnosis and management of heart disease. Magnetic resonance imaging (MRI) of the heart can provide clinically useful information on cardiac function, although it is still not routinely used in clinical practice, in part because of limited imaging speed. New accelerated methods for performing cardiovascular MRI (CMR) have the potential to provide both increased imaging speed and robustness to CMR, as well as access to increased functional information. In this review, we will briefly discuss the main methods currently employed to accelerate CMR methods, such as parallel imaging, k-t undersampling and compressed sensing, as well as new approaches that extend the idea of compressed sensing and exploit sparsity to provide richer information of potential use in clinical practice.

Online imaging requires that the reconstruction of current frame only depends on the previous frames, and real time imaging is the desired case. In this work, we propose a novel scheme for real time dynamic magnetic resonance imaging (dMRI) reconstruction. Different from previous methods, the reconstructions of the second frame to the last frame are independent in our scheme, which only require the first frame as the reference image. Therefore, this scheme can be naturally implemented in parallel. After the first frame is reconstructed, all the later frames can be processed as soon as the k-space data are acquired. As an extension of the conventional spatial total variation, a new online model called dynamic total variation is used to exploit the sparsity on both spatial and temporal domains in dMRI. In real time dMRI, each frame is required to be reconstructed very fast. We then design a novel reweighted least squares algorithm to solve the challenging problem. Motivated by the special structure of partial Fourier transform in sparse MRI, this algorithm is accelerated by the preconditioned conjugate gradient descent method. The proposed method is compared with 4 state-of-the-art online and offline methods on two in-vivo cardiac dMRI datasets. The experimental results show that our method significantly outperforms previous online methods, and is comparable to the offline methods in terms of reconstruction accuracy.

Mitral valve abnormalities were not part of modern pathological and clinical descriptions of hypertrophic cardiomyopathy in the 1950s, which focused on left ventricular (LV) hypertrophy and myocyte fiber disarray. Although systolic anterior motion (SAM) of the mitral valve was discovered as the cause of LV outflow tract obstruction in the M-mode echocardiography era, in the 1990s structural abnormalities of the mitral valve became appreciated as contributing to SAM pathophysiology. Hypertrophic cardiomyopathy mitral malformations have been identified at all levels. They occur in the leaflets, usually elongating them, and also in the submitral apparatus, with a wide array of malformations of the papillary muscles and chordae, that can be detected by transthoracic and transesophageal echocardiography and by cardiac magnetic resonance. Because they participate fundamentally in the predisposition to SAM, they have increasingly been repaired surgically. This review critically assesses imaging and measurement of mitral abnormalities and discusses their surgical relief.

BACKGROUND/AIMS: To assess the usefulness of magnetization-tagged magnetic resonance imaging (MRI) in quantifying cardiac-induced liver motion and deformation in order to predict liver fibrosis. METHODS: This retrospective study included 85 patients who underwent liver MRI including magnetization-tagged sequences from April 2010 to August 2010. Tagged images were acquired in three coronal and three sagittal planes encompassing both the liver and heart. A Gabor filter bank was used to measure the maximum value of displacement (MaxDisp) and the maximum and minimum values of principal strains (MaxP1 and MinP2, respectively). Patients were divided into three groups (no fibrosis, mild-to-moderate fibrosis, and significant fibrosis) based on their aspartate-aminotransferase-to-platelet ratio index (APRI) score. Group comparisons were made using ANOVA tests. RESULTS: The patients were divided into three groups according to APRI scores: no fibrosis (1.5; n=21). The values of MaxDisp were 2.9+/-0.9 (mean+/-SD), 2.3+/-0.7, and 2.1+/-0.6 in the no fibrosis, moderate fibrosis, and significant fibrosis groups, respectively (P<0.001); the corresponding values of MaxP1 were 0.05+/-0.2, 0.04+/-0.02, and 0.03+/-0.01, respectively (P=0.002), while those of MinP2 were -0.07+/-0.02, -0.05+/-0.02, and -0.04+/-0.01, respectively (P<0.001). CONCLUSIONS: Tagged MRI to quantify cardiac-induced liver motion can be easily incorporated in routine liver MRI and may represent a helpful complementary tool in the diagnosis of early liver fibrosis.

PURPOSE: To develop a novel framework for free-breathing MRI called XD-GRASP, which sorts dynamic data into extra motion-state dimensions using the self-navigation properties of radial imaging and reconstructs the multidimensional dataset using compressed sensing. METHODS: Radial k-space data are continuously acquired using the golden-angle sampling scheme and sorted into multiple motion-states based on respiratory and/or cardiac motion signals derived directly from the data. The resulting undersampled multidimensional dataset is reconstructed using a compressed sensing approach that exploits sparsity along the new dynamic dimensions. The performance of XD-GRASP is demonstrated for free-breathing three-dimensional (3D) abdominal imaging, two-dimensional (2D) cardiac cine imaging and 3D dynamic contrast-enhanced (DCE) MRI of the liver, comparing against reconstructions without motion sorting in both healthy volunteers and patients. RESULTS: XD-GRASP separates respiratory motion from cardiac motion in cardiac imaging, and respiratory motion from contrast enhancement in liver DCE-MRI, which improves image quality and reduces motion-blurring artifacts. CONCLUSION: XD-GRASP represents a new use of sparsity for motion compensation and a novel way to handle motions in the context of a continuous acquisition paradigm. Instead of removing or correcting motion, extra motion-state dimensions are reconstructed, which improves image quality and also offers new physiological information of potential clinical value. Magn Reson Med, 2015. (c) 2015 Wiley Periodicals, Inc.

Undifferentiated pleomorphic sarcoma (UPS), previously known as malignant fibrous histiocytoma, is a neoplasm that occurs most often in the extremities, trunk, and retroperitoneum. Rarely, UPS can occur in the cardiac chambers and great vessels. The diagnosis of UPS is difficult to establish with noninvasive imaging techniques, and these tumors may be mistaken for benign neoplasms preoperatively. Surgical excision is the standard therapy, although the extent and location of the tumor may limit the ability to perform a complete resection. Adjuvant chemotherapy and/or radiation are often used for incomplete resections. We report the case of a 57-year-old woman with a large right ventricular UPS who presented with signs of right-sided heart failure. Preoperative imaging was suggestive of a myxoma; however, histopathologic evaluation of the specimen confirmed a diagnosis of UPS. Microscopic margins of the specimen were positive, and adjuvant chemotherapy was given. We discuss diagnostic and treatment considerations for this unusual cardiac tumor. <Learning objective: The diagnosis and treatment of primary cardiac tumors are challenging. Noninvasive imaging often lacks the sensitivity and specificity to differentiate between benign and malignant neoplasms. In addition, the extent and location of tumor involvement may limit the ability to perform a complete resection. The diagnosis and treatment of right ventricular undifferentiated pleomorphic sarcoma are discussed.>.

Echocardiography is the preferred initial imaging method for assessment of cardiac masses. Cardiac magnetic resonance (CMR) imaging, with its excellent tissue characterization and wide field of view, may provide additional unique information. We evaluated the predictive value of echocardiography and CMR imaging parameters to identify tumors and malignancy and to provide histopathologic diagnosis of cardiac masses. Fifty patients who underwent CMR evaluation of a cardiac mass with subsequent histopathologic diagnosis were identified. Echocardiography was available in 44 of 50 cases (88%). Echocardiographic and CMR characteristics were evaluated for predictive value in distinguishing tumor versus nontumor and malignant versus nonmalignant lesions using histopathology as the gold standard. The Wilcoxon rank-sum test was used to compare the 2 imaging methods' ability to provide the correct histopathologic diagnosis. Parameters associated with tumor included location outside the right atrium, T2 hyperintensity, and contrast enhancement. Parameters associated with malignancy included location outside the cardiac chambers, nonmobility, pericardial effusion, myocardial invasion, and contrast enhancement. CMR identified 6 masses missed on transthoracic echocardiography (4 of which were outside the heart) and provided significantly more correct histopathologic diagnoses compared to echocardiography (77% vs 43%, p <0.0001). In conclusion, CMR offers the advantage of identifying paracardiac masses and providing crucial information on histopathology of cardiac masses.

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)