Hyuk-Jae Chang

Accelerated Cardiac Diffusion Tensor Imaging Using Joint Low-Rank and Sparsity Constraints

Objective: The purpose of this paper is to accelerate cardiac diffusion tensor imaging (CDTI) by integrating low-rankness and compressed sensing. Methods: Diffusion-weighted images exhibit both transform sparsity and low-rankness. These properties can jointly be exploited to accelerate CDTI, especially when a phase map is applied to correct for the phase inconsistency across diffusion directions, thereby enhancing low-rankness. The proposed method is evaluated both ex vivo and in vivo, and is compared to methods using either a low-rank or sparsity constraint alone. Results: Compared to using a low-rank or sparsity constraint alone, the proposed method preserves more accurate helix angle features, the transmural continuum across the myocardium wall, and mean diffusivity at higher acceleration, while yielding significantly lower bias and higher intraclass correlation coefficient. Conclusion: Low-rankness and compressed sensing together facilitate acceleration for both ex vivo and in vivo CDTI, improving reconstruction accuracy compared to employing either constraint alone. Significance: Compared to previous methods for accelerating CDTI, the proposed method has the potential to reach higher acceleration while preserving myofiber architecture features, which may allow more spatial coverage, higher spatial resolution, and shorter temporal footprint in the future.

Assessment of multidirectional movements of the common carotid artery in atherothrombotic stroke using dimensional speckle tracking carotid ultrasonography: A prospective, controlled cohort study

We aimed to explore the relevance of multidirectional movements of the common carotid artery in atherothrombotic stroke.

Quantification of Coronary Atherosclerosis in the Assessment of Coronary Artery Disease

Background: Diagnosis of coronary artery disease and management strategies have relied solely on the presence of diameter stenosis ≥50%. We assessed whether direct quantification of plaque burden (PB) and plaque characteristics assessed by coronary computed tomography angiography could provide additional value in terms of predicting rapid plaque progression. Methods and Results: From a 13-center, 7-country prospective observational registry, 1345 patients (60.4±9.4 years old; 57.1% male) who underwent repeated coronary computed tomography angiography >2 years apart were enrolled. For conventional angiographic analysis, the presence of stenosis ≥50%, number of vessel involved, segment involvement score, and the presence of high-risk plaque feature were determined. For quantitative analyses, PB and annual change in PB (△PB/y) in the entire coronary tree were assessed. Clinical outcomes (cardiac death, nonfatal myocardial infarction, and coronary revascularization) were recorded. Rapid progressors, defined as a patient with ≥median value of △PB/y (0.33%/y), were older, more frequently male, and had more clinical risk factors than nonrapid progressors (all P<0.05). After risk adjustment, addition of baseline PB improved prediction of rapid progression to each angiographic assessment of coronary artery disease, and the presence of high-risk plaque further improved the predictive performance (all P<0.001). For prediction of adverse outcomes, adding both baseline PB and △PB/y showed best predictive performance (C statistics, 0.763; P<0.001). Conclusions: Direct quantification of atherosclerotic PB in addition to conventional angiographic assessment of coronary artery disease might be beneficial for improving risk stratification of coronary artery disease. Clinical Trial Registration: URL: https://www.clinicaltrials.gov. Unique identifier: NCT02803411.

Generation of Triangular Mesh of Coronary Artery Using Mesh Merging

Generating a 3D surface model from coronary artery segmentation helps to not only improve the rendering efficiency but also the diagnostic accuracy by providing physiological informations such as fractional flow reserve using computational fluid dynamics (CFD). This paper proposes a method to generate a triangular surface mesh using vessel structure information acquired with coronary artery segmentation. The marching cube algorithm is a typical method for generating a triangular surface mesh from a segmentation result as bit mask. But it is difficult for methods based on marching cube algorithm to express the lumen of thin, small and winding vessels because the algorithm only works in a three-dimensional (3D) discrete space. The proposed method generates a more accurate triangular surface mesh for each singular vessel using vessel centerlines, normal vectors and lumen diameters estimated during the process of coronary artery segmentation as the input. Then, the meshes that are overlapped due to branching are processed by mesh merging and merged into a coronary mesh.

CHARACTERIZING CHRONIC MYOCARDIAL INFARCTIONS IN PATIENTS USING NATIVE T1-BASED CARDIOVASCULAR MAGNETIC RESONANCE

Late Gadolinium Enhancement (LGE) Cardiovascular Magnetic Resonance (CMR) is the gold standard for characterizing chronic myocardial infarctions (CMIs), but it is contraindicated in patients with end-stage chronic kidney disease. We investigated whether native T1 mapping at 3T can reliably

PROGNOSTIC UTILITY OF CORONARY ATHEROSCLEROSIS IN THE ABSENCE OF STENOSIS: A PROSPECTIVE MULTICENTER INTERNATIONAL STUDY OF 6,656 PATIENTS UNDERGOING CORONARY COMPUTED TOMOGRAPHIC ANGIOGRAPHY

Coronary atherosclerosis can exist in the absence of concurrent stenosis due to positive arterial remodeling, but whether these lesions are related to future adverse prognosis is unknown. We explored the prevalence and prognosis for stable patients who exhibited atherosclerotic plaque without

DIFFERENTIAL IMPACT OF TRADITIONAL RISK FACTORS FOR PREDICTING THE PROBABILITY OF OBSTRUCTIVE CORONARY ARTERY DISEASE IN MEN AND WOMEN WITH CHEST PAIN: RESULTS FROM THE MULTINATIONAL CONFIRM REGISTRY

Whether certain traditional risk factors (RFs) provide greater predictive strength for obstructive coronary artery disease (≥50p diameter stenosis, “OCAD”) in patients with chest pain is unknown. From 8106 consecutive patients (mean age 58 years, 3999 men) without CAD history