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Introduction
Deep learning for computer vision
Current institution
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September 2006 - February 2015
Publications
Publications (112)
Agriculture is an essential component of human sustenance in this world. These days, with a growing population, we must significantly increase agricultural productivity to meet demand. Agriculture moved toward technologies as a result of the demand for higher yields with less resources. Increasing awareness of the significance and influence of agri...
Biomedical image segmentation plays a vital role in diagnosis of diseases across various organs. Deep learning-based object detection methods are commonly used for such segmentation. There exists an extensive research in this topic. However, there is no standard review on this topic. Existing surveys often lack a standardized approach or focus on b...
Background
Machine learning (ML) models have been proposed to predict risk related to transvenous lead extraction (TLE).
Objective
We tested if integrating imaging data into an existing ML model increases its ability to predict major adverse events (MAE: procedure-related major complications and procedure-related deaths) and lengthy procedures (≥1...
The automatic segmentation of coronary arteries in X-Ray angiograms has a significant role in identification and detection of various abnormalities in vessels which can be adequately helpful in computer aided diagnosis (CAD) for supporting in analyzing the coronary heart diseases. Previously many machine learning (ML) algorithms and deep learning (...
In order to improve patient outcomes, brain tumors—which are notorious for their catastrophic effects and short life expectancy, particularly in higher grades—need to be diagnosed accurately and treated with care. Patient survival chances may be hampered by incorrect medical procedures brought on by a brain tumor misdiagnosis. CNNs and computer-aid...
Early detection of diabetic retinopathy, a complication of vision loss in advanced stages of diabetes, is essential to avoid permanent blindness. However, the automatic detection of diabetic retinopathy through medical image processing requires a large number of training data to build a model with good performance. This poses a challenge when worki...
Severe stages of diabetes can eventually lead to an eye condition called diabetic retinopathy. It is one of the leading causes of temporary visual disability and permanent blindness. There is no cure for this disease other than a proper treatment in the early stages. Five stages of diabetic retinopathy are discussed in this paper that need to be de...
The lead extraction procedures are for the patients who already have pacemaker implanted and leads need to be replaced. The procedure is a high-risk procedure and it could lead to major complications or even procedure-related death. Recently, an Electra Registry Outcome Score (EROS) was designed to create a risk assessment tool using the data about...
Human body volume is a useful biometric feature for human identification and an important medical indicator for monitoring body health. Traditional body volume estimation techniques such as underwater weighing and air displacement demand a lot of equipment, and are difficult to be performed under some circumstances, e.g. in clinical environments wh...
The lead extraction procedures are for the patients who already have pacemaker implanted and leads need to be replaced. The procedure is a high-risk procedure and it could lead to major complications or even procedure-related death. Recently, an Electra Registry Outcome Score (EROS) was designed to create a risk assessment tool using the data about...
Severe stages of diabetes can eventually lead to an eye condition called diabetic retinopathy. It is one of the leading causes of temporary visual disability and permanent blindness. There is no cure for this disease other than a proper treatment in the early stages. Five stages of diabetic retinopathy are discussed in this paper that need to be de...
Diabetic retinopathy is the consequence of advanced stages of diabetes, which can ultimately lead to permanent blindness. An early detection of diabetic retinopathy is extremely important to avoid blindness and to recover from it as soon as possible. This chapter discusses the application of recent deep and transfer learning models for medical imag...
Purpose
Reducing X‐ray dose increases safety in cardiac electrophysiology procedures but also increases image noise and artifacts which may affect the discernibility of devices and anatomical cues. Previous denoising methods based on convolutional neural networks (CNNs) have shown improvements in the quality of low‐dose X‐ray fluoroscopy images but...
Objective:
Catheters and wires are used extensively in cardiac catheterization procedures. Detecting their positions in fluoroscopic X-ray images is important for several clinical applications such as motion compensation and co-registration between 2D and 3D imaging modalities. Detecting the complete length of a catheter or wire object as well as...
3D transesophageal echocardiography (TEE) is one of the most significant advances in cardiac imaging. Although TEE provides real-time three-dimensional (3D) visualization of heart tissues and blood vessels and has no ionizing radiation, X-ray fluoroscopy still dominates in guidance of cardiac interventions due to TEE having a limited field of view...
Accurate real-time catheter segmentation is an important pre-requisite for robot-assisted endovascular intervention. Most of the existing learning-based methods for catheter segmentation and tracking are only trained on small-scale datasets or synthetic data due to the difficulties of ground-truth annotation. Furthermore, the temporal continuity in...
Purpose:
Catheters and guidewires are used extensively in cardiac catheterization procedures such as heart arrhythmia treatment (ablation), angioplasty and congenital heart disease treatment. Detecting their positions in fluoroscopic X-ray images is important for several clinical applications, for example, motion compensation, co-registration betw...
Collimators control the field of view (FoV) by using thick blades to block X-rays leaving the source to image the patient. When the blades are adjusted to reduce the FoV, the area of the patient receiving radiation is reduced. Current fluoroscopy systems allow only for manual collimation by the operator. This can be done from the control panel usin...
Guiding catheters and guidewires are used extensively in pediatric cardiac catheterization procedures for congenital heart diseases (CHD). Detecting their positions in fluoroscopic X-ray images is important for several clinical applications, such as visibility enhancement for low dose X-ray images, and co-registration between 2D and 3D imaging moda...
ECG imaging is an emerging technology for the reconstruction of cardiac electric activity from non-invasively measured body surface potential maps. In this case report, we present the first evaluation of transmurally imaged activation times against endocardially reconstructed isochrones for a case of sustained monomorphic ventricular tachycardia (V...
Determination of the cardiorespiratory phase of the heart has numerous
applications during cardiac imaging. In this article we propose a novel
view-angle independent near-real time cardiorespiratory motion gating and
coronary sinus (CS) catheter tracking technique for x-ray fluoroscopy images
that are used to guide cardiac electrophysiology procedu...
Cardiorespiratory phase determination has numerous applications
during cardiac imaging. We propose a novel view-angle independent
prospective cardiorespiratory motion gating technique for X-ray
fluoroscopy images that are used to guide cardiac electrophysiology procedures.
The method is based on learning coronary sinus catheter motion
using princip...
Echocardiography is a potential alternative to X-ray fluoroscopy in cardiac catheterization given its richness in soft tissue information and its lack of ionizing radiation. However, its small field of view and acoustic artifacts make direct automatic segmentation of the catheters very challenging. In this study, a fast catheter segmentation framew...
Purpose:
Image-guided cardiac interventions involve the use of fluoroscopic images to guide the insertion and movement of interventional devices. Cardiorespiratory gating can be useful for 3D reconstruction from multiple x-ray views and for reducing misalignments between 3D anatomical models overlaid onto fluoroscopy.
Methods:
The authors propos...
Surface flattening in medical imaging has seen widespread use in neurology and more recently in cardiology to describe the left ventricle using the bull's-eye plot. The method is particularly useful to standardize the display of functional information derived from medical imaging and catheter-based measurements. We hypothesized that a similar appro...
3D soft tissue information, which X-ray images cannot provide but 3D echocardiographic imaging can, may be required in cardiac catheter-based interventions. In this paper, we propose a real-time catheter tracking strategy in echocardiographic sequences based on catheter segmentation in 2D X-ray images and registration between these two modalities....
Real-time imaging is required to guide minimally invasive catheter-based cardiac interventions. While transesophageal echocardiography allows for high-quality visualization of cardiac anatomy, X-ray fluoroscopy provides excellent visualization of devices. We have developed a novel image fusion system that allows real-time integration of 3-D echocar...
The motion and deformation of catheters that lie inside cardiac structures can provide valuable information about the motion of the heart. In this paper we describe the formation of a novel statistical model of the motion of a coronary sinus (CS) catheter based on principal component analysis of tracked electrode locations from standard mono-plane...
Purpose:
X-ray fluoroscopically guided cardiac electrophysiology (EP) procedures are commonly carried out to treat patients with arrhythmias. X-ray images have poor soft tissue contrast and, for this reason, overlay of a three-dimensional (3D) roadmap derived from preprocedural volumetric images can be used to add anatomical information. It is use...
Image guidance of minimally invasive cardiac interventions can be augmented by registering together different imaging modalities. In this paper, we propose a method to combine three modalities: X-ray fluoroscopy, trans-esophageal ultrasound and pre-procedure MRI or CT. The registration of the pre-procedure image involves a potentially unreliable ma...
Body surface potential mapping (BSPM) can be used to non-invasively measure the electrical activity of the heart using a dense set of thorax electrodes and a CT/MR scan of the thorax to solve the inverse problem of electrophysiology (ECGi). This technique now shows potential clinical value for the assessment and treatment of patients with arrhythmi...
Although X-ray imaging has played a dominant role in cardiac catheter-based interventions, sometimes 3D soft tissue information, which X-ray images cannot provide, may be required. In contrast, 3D echocardiographic imaging is able to visualise soft tissue. In this paper, we propose a real-time catheter tracking strategy in echocardiographic sequenc...
The use of ultrasound imaging for guidance of cardiac interventional procedures is limited by the small field of view of the ultrasound volume. A larger view can be created by image-based registration of several partially overlapping volumes, but automatic registration is likely to fail unless the registration is initialized close to the volumes' c...
Background Cardiac magnetic resonance (CMR) imaging enables characterization of myocardial scar and the ‘grey zone’, an admixture of scar and healthy myocardium, which is an independent predictor of ventricular arrhythmia. We explored the relationship between the grey zone and ventricular tachycardia circuits (VT) in ischaemic cardiomyopathy. Metho...
A 60-year-old man underwent attempted cardiac resynchronization with defibrillator therapy utilizing a left-sided approach. A persistent left-sided superior vena cava (SVC) was identified and a dual-coil defibrillator lead (Sprint Fidelis; Medtronic) and atrial lead were deployed via this route ( Figure 1A ). No left ventricular (LV) branches of …
An electrostatic dry coating process based on a liquid pan coater was developed for enteric coating of tablets with Eudragit(®) L100-55. Two different liquid plasticizers of triethyl citrate (TEC) and PEG400 were used in the coating process. In contrast to TEC, PEG400 produced good powder adhesion and successful coating. DSC results showed that PEG...
Aims:
Left ventricular (LV) lead positioning for cardiac resynchronization therapy (CRT) is largely empirical and operator-dependent. Our aim was to determine whether cardiac magnetic resonance (CMR)-guided CRT may improve the acute and the chronic response.
Methods and results:
CMR-derived anatomical models and dyssynchrony maps were created fo...
Delayed-enhancement magnetic resonance imaging (DE-MRI) is an effective technique for imaging left ventricular (LV) infarct. Existing techniques for LV infarct segmentation are primarily threshold-based making them prone to high user variability. In this work, we propose a segmentation algorithm that can learn from training images and segment based...
This paper presents collated results from the Delayed Enhancement MRI (DE-MRI) segmentation challenge at MICCAI 2012. DE-MRI Images from fifteen patients and fifteen pigs were randomly selected from two different imaging centres. Three independent sets of manual segmentations were obtained for each image and included in this study. A ground truth c...
X-ray fluoroscopic images are widely used for image guidance in cardiac electrophysiology (EP) procedures to diagnose or treat cardiac arrhythmias based on catheter ablation. However, the main disadvantage of fluoroscopic imaging is the lack of soft tissue information and harmful radiation. In contrast, ultrasound (US) has the advantages of low-cos...
Minimally invasive cardiac surgery is made possible by image guidance technology. X-ray fluoroscopy provides high contrast images of catheters and devices, whereas 3D ultrasound is better for visualising cardiac anatomy. We present a system in which the two modalities are combined, with a trans-esophageal echo volume registered to and overlaid on a...
Gating of X-ray fluoroscopy images is required for catheter reconstruction for registration of pre-procedural images with fluoroscopy for guidance and biophysical modelling. We propose a novel and clinically useful retrospective method for automatic image-based cardiac and respiratory motion gating. The technique is based on tracking and statistica...
X-ray fluoroscopically-guided cardiac catheterization procedures are commonly carried out for the treatment of cardiac arrhythmias, such as atrial fibrillation (AF) and cardiac resynchronization therapy (CRT). X-ray images have poor soft tissue contrast and, for this reason, overlay of a 3D roadmap derived from pre-procedure volumetric image data c...
The use of ultrasound imaging for image guidance of cardiac procedures is limited by the small field of view of the ultrasound volume. A larger view can be created by image-based registration of partially overlapping volumes, but automatic registration often fails unless the volume alignment is initialised close to the volumes' correct alignment. I...
Cardiac electrophysiology procedures are routinely used to treat patients with rhythm disorders. The success rates of ablation procedures and cardiac resynchronization therapy are still sub-optimal. Recent advances in medical imaging, image processing and cardiac biophysical modeling have the potential to improve patient outcome. This manuscript pr...
Cardiac resynchronization therapy (CRT) is an effective procedure for patients with heart failure but 30% of patients do not respond. This may be due to sub-optimal placement of the left ventricular (LV) lead. It is hypothesized that the use of cardiac anatomy, myocardial scar distribution and dyssynchrony information, derived from cardiac magnetic...
A novel active and multi-dose dry powder inhaler (DPI) was developed and evaluated to deliver a small quantity (100-500 μg) of pure drug without any excipient. This dry powder inhaler utilized two compressed air flows to dispense and deliver drug powder: the primary flow aerosolizes the drug powder from its pocket and the secondary flow further dis...
It is not clear whether there is a large difference in acute hemodynamic response (AHR) to left ventricle (LV) pacing in different regions of the same coronary sinus (CS) vein. Using the four electrodes available on a Quartet LV lead, we evaluated the AHR to pacing within individual branches of the CS.
An acute hemodynamic study was attempted in 20...
Multi-site left ventricular (LV) pacing may be superior to single-site stimulation in correcting dyssynchrony and avoiding areas of myocardial scar. We sought to characterize myocardial scar using cardiac magnetic resonance imaging (CMR). We aimed to quantify the acute haemodynamic response to single-site and multi-site LV stimulation and to relate...
X-ray fluoroscopically guided cardiac electrophysiological procedures are routinely carried out for diagnosis and treatment of cardiac arrhythmias. X-ray images have poor soft tissue contrast and, for this reason, overlay of static 3-D roadmaps derived from preprocedural volumetric data can be used to add anatomical information. However, the regist...
X-ray fluoroscopically guided cardiac ablation procedures are commonly carried out for the treatment of cardiac arrhythmias,
such as atrial fibrillation (AF). X-ray images have poor soft tissue contrast and, for this reason, overlay of a 3D roadmap
derived from pre-procedural volumetric image data can be used to add anatomical information. It is a...
IntroductionOptimal left ventricular (LV) lead placement via the coronary sinus (CS) is a critical factor in defining response to cardiac resynchronisation therapy (CRT). Using novel semi-automated image acquisition, segmentation, overlay and registration software we set out to guide lead placement by avoiding scar and targeting the region of the L...
IntroductionCardiac resynchronisation therapy (CRT) usually involves placing the left ventricular (LV) pacing lead in the postero-lateral or lateral region of the LV epicardial surface as this is thought likely to re-coordinate myocardial contraction most effectively. The LV lead is standardly placed in a position with the best pacing parameters an...
X-ray fluoroscopically guided cardiac electrophysiological procedures are routinely carried out for diagnosis and treatment of cardiac arrhythmias. Xray images have poor soft tissue contrast and, for this reason, overlay of static 3D roadmaps derived from pre-procedural volumetric data can be used to add anatomical information. However, the registr...
Two-dimensional (2D) X-ray imaging is the dominant imaging modality for cardiac interventions. However, the use of X-ray fluoroscopy alone is inadequate for the guidance of procedures that require soft-tissue information, for example, the treatment of structural heart disease. The recent availability of three-dimensional (3D) trans-esophageal echoc...
Background:
Failure rate for left ventricular (LV) lead implantation in cardiac resynchronization therapy (CRT) is up to 12%. The use of segmentation tools, advanced image registration software, and high-fidelity images from computerized tomography (CT) and cardiac magnetic resonance (CMR) of the coronary sinus (CS) can guide LV lead implantation....
Optimal left ventricular (LV) lead placement via the coronary sinus (CS) is a critical factor in defining response to cardiac
resynchronization therapy (CRT). Using novel MR image acquisition, segmentation, overlay and registration software we set
out to guide lead placement by avoiding scar and targeting the LV region with the latest mechanical ac...
The objectives of this study were to develop an electrostatic dry powder coating process for sustained coating tablets with Eudragit(®) RS/RL and to investigate the effects of various factors and operating conditions on the coating process and drug release profile. A liquid plasticizer (triethyl citrate) was sprayed onto the surface of the tablets...
Cardiac resynchronization therapy (CRT) can be an effective procedure for patients with heart failure but 30% of patients do not respond. This may be partially caused by the sub-optimal placement of the left ventricular lead. We demonstrate how pre-procedural cardiac MR images can be used to assist CRT by integration of anatomical and functional in...
An electrostatic dry powder coating process for pharmaceutical solid dosage forms was developed for the first time by electrostatic dry powder coating in a pan coater system. Two immediate release coating compositions with Opadry® AMB and Eudragit® EPO were successfully applied using this process. A liquid plasticizer was sprayed onto the surface o...
Persistent left superior vena cava can lead to significant technical difficulties when implanting a left ventricular (LV) lead for cardiac resynchronisation therapy. We present two cases in which coronary sinus anatomy was reconstructed with computed tomography and magnetic resonance imaging and fused with live fluoroscopy to facilitate LV lead imp...
Cardiac resynchronization therapy (CRT) can be an effective procedure for patients with heart failure but 30% of patients
do not respond. This may be partially caused by the sub-optimal placement of the left ventricular (LV) lead. Detailed cardiac
anatomy and dyssynchrony information could improve optimal LV lead placement. As a pre-interventional...
X-ray fluoroscopically guided cardiac electrophysiological procedures are routinely carried out for diagnosis and treatment of cardiac arrhythmias. X-ray images have poor soft tissue contrast and, for this reason, overlay of static 3D roadmaps derived from pre-procedural volumetric data can be used to add anatomical information. However, the regist...
We present a feasibility study on hybrid echocardiography (echo) and x-ray image guidance for cardiac catheterization procedures. A self-tracked, remotely operated robotic arm with haptic feedback was developed that attached to a standard x-ray table. This was used to safely manipulate a three-dimensional (3D) trans-thoracic echo probe during simul...
Whole heart segmentation of 3D ultrasound (US), also referred to as echocardiography or simply echo, is useful in cardiac functional analysis to achieve quantitative diagnostic information of the heart. However, characteristics of US imaging such as limited field-of-view, artifacts and inconsistent intensity distribution makes automated approaches...
For many image-guided interventions there exists a need to compute the registration between preprocedure image(s) and the physical space of the intervention. Real-time intraprocedure imaging such as ultrasound (US) can be used to image the region of interest directly and provide valuable anatomical information for computing this registration. Unfor...
A novel method is proposed to compute the minimum distance between two 2D or 3D NURBS curves using control polygons in an efficient and robust way. The first step is to decompose both of NURBS curves into their piecewise Bzier forms. The second step is to use a two level selection process to select a subset of all possible pairs. The first level se...
We present an initial evaluation of a robotic arm for positioning a 3D echo probe during cardiac catheterization procedures. By tracking the robotic arm, X-ray table and X-ray C-arm, we are able to register the 3D echo images with live 2D X-ray images. In addition, we can also use tracking data from the robotic arm combined with system calibrations...
We present a robust method to register three-dimensional echocardiography (echo) images to magnetic resonance images (MRI) based on anatomical features, which is designed to be used in the registration pipeline for overlaying MRI-derived roadmaps onto two-dimensional live x-ray images during cardiac catheterization procedures. The features used in...
3D ultrasound has attracted considerable interest in recent years as a low cost, mobile and real-time imaging modality for interventional cardiac applications. However, the low image quality and small field of view have been two major barriers preventing 3D ultrasound from being widely accepted as a solution to the guidance of cardiac interventions...
We describe a system for respiratory motion correction of MRI-derived roadmaps for use in X-ray guided cardiac catheterisation procedures. The technique uses a subject-specific affine motion model that is quickly constructed from a short pre-procedure MRI scan. We test a dynamic MRI sequence that acquires a small number of high resolution slices, r...
We present a novel method to register three-dimensional echocardiography (echo) images with magnetic resonance images (MRI) based on anatomical features, which could be used in the registration pipeline for overlaying MRI-derived roadmaps onto two-dimensional live X-ray images in electrophysiology (EP) procedures. The features used in image registr...
We present a technique for automatic intensity-based image-to-physical registration of a 3-D segmentation for image-guided interventions. The registration aligns the segmentation with tracked and calibrated 3-D ultrasound (US) images of the target region. The technique uses a probabilistic framework and explicitly incorporates a model of the US ima...
Real-time visualization plays an important role in medical imaging applications such as image-guided surgery, surgical simulation and medical education. For the real-time visualization and the simultaneous overlay of 3D triangulated objects onto live recordings of patient data gathered with fast imaging devices (e.g. from the beating heart) it is e...
Angiogenic sprouts at the leading edge of an expanding vascular plexus are recognised as major regulators of the structure of the developing network. Early in sprout development, a vascular lumen is often evident which communicates with the parent vessel while the distal tip is blind-ended. Here we describe the temporal evolution of blind-ended ves...
Dry coating is a coating technology for solid pharmaceutical dosage forms derived from powder coating of metals. In this technology, powdered coating materials are directly coated onto solid dosage forms without using any solvent, and then heated and cured to form a coat. As a result, this technology can overcome such disadvantages caused by solven...
A hybrid X-ray and magnetic resonance imaging system (XMR) has been proposed as an interventional guidance for cardiovascular catheterisation procedure. However, very few hospitals can benefit from the XMR system because of its limited availability. In this paper we describe a new guidance strategy for cardiovascular catheterisation procedure. In o...
This paper presents the evaluation of the use of multimodality skin markers for the registration of cardiac magnetic resonance (MR) image data to x-ray fluoroscopy data for the guidance of cardiac electrophysiology procedures. The approach was validated using a phantom study and 3 patients undergoing pulmonary vein (PV) isolation for the treatment...
This paper presents a technique for compensating for respiratory motion and deformation in an augmented reality system for cardiac catheterisation procedures. The technique uses a subject-specific affine model of cardiac motion which is quickly constructed from a pre-procedure magnetic resonance imaging (MRI) scan. Respiratory phase information is...
We present a novel method to calibrate a D ultrasound probe which has a 2D transducer array. By optically tracking a calibrated 3D probe we are able to produce extended field of view D ultrasound images. Tracking also enables us to register our ultrasound images to other tracked and calibrated surgical instruments or to other tracked and calibrated...
This paper presents a technique for compensating for respiratory motion and deformation in an augmented reality system for cardiac catheterisation procedures. The technique uses a subject-specific affine model of cardiac motion which is quickly constructed from a pre-procedure magnetic resonance imaging (MRI) scan. Respiratory phase information is...
In this paper we describe a novel 3D subdivision strategy to extract the surface of binary image data. This iterative approach generates a series of surface meshes that capture different levels of detail of the underlying structure. At the highest level of detail, the resulting surface mesh generated by our approach uses only about 10% of the trian...
Visualization plays an important role in image guided surgery. This paper presents a real-time 3D motion visualization method where pre-computed meshes of the beating heart are synchronized with and overlaid onto live X-ray images. This provides the surgeon with a navigational aid in guiding catheters during cardiac catheterization. In order to gen...
Cardiac arrhythmias are increasingly being treated using ablation procedures. Development of fast electrophysiological models
and estimation of parameters related to conduction pathologies can aid in the investigation of better treatment strategies
during Radio-frequency ablations. We present a fast electrophysiological model incorporating anisotro...
Cardiac arrhythmias are increasingly being treated using ablation procedures. Development of fast electrophysiological models and estimation of parameters related to conduction pathologies can aid in the investigation of better treatment strategies during Radio-frequency ablations. We present a fast electrophysiological model incorporating anisotro...
Analyzing dynamic biological systems, such as blood vessel growth in healing wounds or tumour development, requires high spatial and temporal resolution. Intravital fluorescence microscopy allows for longitudinal subcellular imaging, but it requires the use of advanced image analysis tools in order to quantitatively extract the relevant parameters...