Zhi Chen's research while affiliated with University of Iowa and other places
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Publications (50)
Accurate segmentation of retinal layers in optical coherence tomography (OCT) images is critical for assessing diseases that affect the optic nerve, but existing automated algorithms often fail when pathology causes irregular layer topology, such as extreme thinning of the ganglion cell-inner plexiform layer (GCIPL). Deep LOGISMOS, a hybrid approac...
Background
There is conflicting evidence on the role of acetylsalicylic acid (ASA) use in the development of cardiac allograft vasculopathy (CAV).
Methods
A nationwide prospective two‐center study investigated changes in the coronary artery vasculature by highly automated 3‐D optical coherence tomography (OCT) analysis at 1 month and 12 months aft...
p>Image segmentation is a fundamental problem in medical image analysis. Deep learning (DL) methods have achieved state-of-the-art (SOTA) results in various medical image segmentation tasks. This success is largely attributable to the use of large annotated datasets for training. However, due to anatomical variations and complexity of medical image...
p>Image segmentation is a fundamental problem in medical image analysis. Deep learning (DL) methods have achieved state-of-the-art (SOTA) results in various medical image segmentation tasks. This success is largely attributable to the use of large annotated datasets for training. However, due to anatomical variations and complexity of medical image...
Background:
The association between genetic polymorphisms and early cardiac allograft vasculopathy (CAV) development is relatively unexplored. Identification of genes involved in the CAV process may offer new insights into pathophysiology and lead to a wider range of therapeutic options.
Methods:
This prospective study of 109 patients investigat...
Optical Coherence Tomography (OCT) is an intravascular imaging modality enabling detailed evaluation of cardiac allograft vasculopathy (CAV) after heart transplantation (HTx). However, its clinical application remains hampered by time-consuming manual quantitative analysis. We aimed to validate a semi-automated quantitative OCT analysis software (I...
Background
Imaging-based characteristics associated with the progression of stable coronary atherosclerotic lesions are poorly defined. Utilizing a combination of optical coherence tomography (OCT) and intravascular ultrasound (IVUS) imaging, we aimed to characterize the lesions prone to progression through clinical validation of a semiautomated OC...
Background
The FiGARO (FFR versus iFR in Assessment of Hemodynamic Lesion Significance, and an Explanation of Their Discrepancies) trial is a prospective registry searching for predictors of fractional flow reserve/instantaneous wave‐free ratio (FFR/iFR) discrepancy.
Methods and Results
FFR/iFR were analyzed using a Verrata wire, and coronary flow...
Objective:
The aim of the study was to test the potential role of breast arterial calcification (BAC) in the prediction of coronary artery disease (CAD) in women. The criterion standard for CAD diagnostics was coronary angiography.
Methods:
This retrospective study enrolled 163 consecutive women, who underwent digital mammography and coronary an...
Automated segmentation of individual calf muscle compartments from 3D magnetic resonance (MR) images is essential for developing quantitative biomarkers for muscular disease progression and its prediction. Achieving clinically acceptable results is a challenging task due to large variations in muscle shape and MR appearance. In this paper, we prese...
Introduction:
Recent studies suggested potential positive correlations between HLA-specific antibodies and development of cardiac allograft vasculopathy (CAV).
Methods:
This prospective two-center study investigated early progression of CAV by coronary optical coherence tomography in 1 month and 12 months after heart transplantation (HTx) in 104...
Automated segmentation of individual calf muscle compartments from 3D magnetic resonance (MR) images is essential for developing quantitative biomarkers for muscular disease progression and its prediction. Achieving clinically acceptable results is a challenging task due to large variations in muscle shape and MR appearance. Although deep convoluti...
The mechanisms of plaque development are still not entirely understood. Intravascular ultrasound (IVUS) is a preferred modality to assess complex plaque structures in coronary arteries. Virtual histology (VH) determines one of four plaque types for each coronary wall location. Serial imaging over multiple time points assesses plaque development in...
Introduction:
Heart rate slowing agents are frequently prescribed to manage heart transplant (HTx) patients with the assumption that higher heart rate is a risk factor in cardiovascular disease.
Patients and methods:
This prospective two-centre study investigated early progression of cardiac allograft vasculopathy (CAV) in 116 HTx patients. Exam...
Purpose:
There is no prevention or treatment for diabetic retinal neurodegeneration (DRN), which is a complication of diabetes that can occur independently of diabetic retinopathy (DR). We hypothesized that an intravitreal fluocinolone acetonide (FAc) implant may affect the rate of DRN when used in patients with diabetic macular edema (DME).
Meth...
Background: We tested whether the level of endothelial dysfunction assessed by digital tonometry, and expressed as reactive hyperemia index (RHI), is related to occurrences of a discrepancy between fractional flow reserve (FFR) and the instantaneous wave free ratio (iFR) (ClinicalTrials.gov identifier: NCT03033810).
Methods: We examined patients wi...
Background:
We studied a novel approach for the evaluation and management of volemia: minimally invasive monitoring of respiratory blood flow variations in the superior vena cava (SVC). We performed an experiment with 10 crossbred (Landrace × large white) female pigs (Sus scrofa domestica).
Methods:
Hypovolemia was induced by bleeding from a fem...
Cardiac allograft vasculopathy (CAV) accounts for about 30% of all heart-transplant (HTx) patient deaths. For patients at high risk for CAV complications after HTx, therapy must be initiated early to be effective. Therefore, new phenotyping approaches are needed to identify such HTx patients at the earliest possible time. Coronary optical coherence...
Background:
Optical coherence tomography (OCT)-based studies of cardiac allograft vasculopathy (CAV) published thus far have focused mainly on frame-based qualitative analysis of the vascular wall. Full capabilities of this inherently 3-dimensional (3D) imaging modality to quantify CAV have not been fully exploited.
Methods:
Coronary OCT imaging...
Background
Coronary atherosclerosis progresses faster in patients with diabetes mellitus (DM) and causes higher morbidity and mortality in such patients compared to non-diabetics ones (non-DM). We quantify changes in plaque volume and plaque phenotype during lipid-lowering therapy in DM versus non-DM patients using advanced intracoronary imaging....
Features of high-risk coronary artery plaques prone to major adverse cardiac events (MACE) were identified by intravascular ultrasound (IVUS) virtual histology (VH). These plaque features are: Thin-cap fibroatheroma (TCFA), plaque burden PB≥70%, or minimal luminal area MLA≤4mm². Identification of arterial locations likely to later develop such high...
Resumen
Introducción y objetivos
Se ha considerado que el engrosamiento intimal patológico (EIP) es un fenotipo de placa benigno. Se presentan los cambios fenotípicos de la placa en un estudio comparativo entre situación basal y seguimiento mediante un estudio de reconstrucción histológica virtual por ecografía intravascular.
Métodos
Se estudió a...
Introduction and objectives:
Pathologic intimal thickening (PIT) has been considered a benign plaque phenotype. We report plaque phenotypic changes in a baseline/follow-up intravascular ultrasound-based virtual histology study.
Methods:
A total of 61 patients with stable coronary artery disease were analyzed from the HEAVEN trial (89 patients ra...
Background and aim:
To study relationships between endothelial dysfunction (ED) and coronary atherosclerosis derived from intravascular ultrasound (IVUS) and virtual histology (VH).
Methods:
ED was examined by EndoPAT system (Itamar Medical) in 56 patients who underwent IVUS and VH (Volcano corp.). Reactive Hyperemia Index (RHI) < 2 was used for...
The accepted definition of virtual histology intravascular ultrasound (IVUS-VH) thin-cap fibroatheroma (TCFA) is only a modest predictor of plaque rupture. We sought to determine the relationship between IVUS-VH findings and culprit lesions with plaque rupture using computational analysis. A total of 80 culprit lesions from 80 patients with stable...
We present a semi-automated approach to comprehensively examine coronary remodeling over the entire length of intravascular ultrasound (IVUS) imaged vessels. Serial measurements at baseline and 12-month follow-up are analyzed rather than static data obtained at a single time point. Every IVUS pullback is segmented automatically, and then reviewed a...
Thin-cap fibroatheroma (TCFA) is particularly prone to rupture, which may result in myocardial infarction and death. Virtual histology intravascular ultrasound (VH-IVUS) provides quantitative information about plaque composition and enables TCFA identification. However, prospective prediction of future development of TCFA has not been previously po...
A novel method is reported for simultaneous registration of location (axial direction) and orientation (circumferential direction) of two intravascular ultrasound (IVUS) pullbacks of the same vessel taken at different times. Monitoring plaque progression or regression (e.g., during lipid treatment) is of high clinical relevance. Our method uses a 3...
A novel method for simultaneous registration of location and orientation of baseline and follow-up intravascular ultrasound (IVUS) pullbacks is reported. The main idea is to represent the registration problem as a 3D graph optimization problem (finding a minimum-cost path) solvable by dynamic programming. Thus, global optimality of the resulting lo...
Spatio-temporal registration of baseline and follow-up intravascular ultrasound (IVUS) pullbacks is of paramount importance in studying the progression/regression of coronary artery disease. Automating these two tasks has the potential to increase productivity when studying large patient populations. Current automated methods are often designed for...
Background: Vascular remodeling is believed to respond to changes in plaque burden and is traditionally classified per vessel as positive (PR) or non-positive (NPR). We introduced a 3rd group to account for segmental variations in coronary remodeling in 32 non-culprit vessels from 32 patients.
Citations
... Potential future work may include extending our layer segmentation approach to simultaneously identify retinal layers and regions with fluid accumulations, including cases with age-related macular degeneration, diabetic retinopathy, and radiation retinopathy. The implemented workflow can also be further enhanced with Just-Enough Interaction (JEI) [39] to allow intuitive and efficient correction of segmentation errors. ...
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... Using our highly automated 3D-OCT analysis, after registering the overlapping baseline and follow-up pullbacks, a total of 40152 registered frame pairs were analysed in 109 patients. This approach is the most detailed quantitative OCT method available for assessing early changes in cardiac vasculature (9,16). During the fi rst post-HTx year, the mean intima thickness signifi cantly increased by 24.0 ± 34.2 μm (p < 0.001). ...
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... Qualitative OCT analysis followed previously established criteria. [8][9][10][11][12] Lipid-rich tissue was defined as a signal-poor region with poorly defined or diffuse borders. Calcifications were defined as signal-poor or heterogeneous regions with sharply delineated border. ...
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... FFR > 0.8 indicates that the lesion is non-significant coronary stenosis and deferred revascularization is recommended. With evidence accumulation, other determinants on prognosis emerged, including the plaque vulnerability and progression [3], the interference of microvascular dysfunction on FFR [4], and other non-coronary factors. A recent meta-analysis containing 4275 patients deferred revascularization following a negative FFR concluded that the cardiovascular events of diabetic patients was 2.08 folds greater than non-diabetic [5]. ...
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... Guo et al. [27] proposed the filterNet which is a variant of the U-Net for segmenting muscle in MRI. The network consists of 3 blocks Fig. 2. Categories of 3D CNN methods for medical images. ...
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... Since OCT can detect small structural changes in coronary arteries, it may be useful for elucidating the pathophysiology of CAV. The association between rejection and OCT findings has been evaluated in several studies [55][56][57]. A retrospective study comparing OCT findings in pediatric and adult HTX recipients suggested age-and time-dependent differences in the prevalence of absolute and relative intimal hyperplasia [58]. ...
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... Consequently, treatment with intravitreal corticosteroids is typically limited to patients with persistent or refractory diabetic macular edema (DME), especially those with pseudophakic eyes [80]. In addition to their ability to counteract the effects of proinflammatory cytokines, corticosteroids have also been found to provide neuroprotection, as demonstrated in both experimental [81] and clinical studies [82]. Furthermore, they possess antiangiogenic properties [83]. ...
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... It improves the boundary detection of the coronary lumen compared to other methods, and identifies the guidewire and plaque shadows in a single step. Furthermore, to the best of our knowledge, only two other studies [23,24] reported on the detection accuracy of intima-media and the media-adventitia boundaries, and only in regions of minimal disease, specifically excluding areas with thickened intima characteristic of atherosclerotic lesions. ...
... The counterpart physics-based methods formulate the segmentation as a diffusion problem [37][38][39]. Despite the success of graphical methods, difficulties arise in low SNR regions with speckle, anatomical anomalies, and external objects, which limit the practical applications of these models and cause a cascade of increasing errors that require follow-up manual corrections done by expert annotators in the post-processing stage [40]. ...
... In the largest observational study, a study to evaluate the effect of rosuvastatin on intravascular ultrasound-derived coronary atheroma burden (ASTEROID), 507 patients treated with a 40 mg dose of rosuvastatin showed a 6.1% reduction in TAV measured by IVUS at the end of 24 months [51] . Another large observational study, Coronary Atherosclerosis Study Measuring Effects of Rosuvastatin Using Intravascular Ultrasound in Japanese Subjects (COSMOS) in 2009, and the Integrated Biomarkers and Imaging Study (IBIS-4) in 2015, also demonstrated similar outcomes using IVUS [52] . ...
