Hybrid Imaging During Transcatheter Structural Heart Interventions

Multi-modality cardiac image computing: A survey

Multi-modality cardiac imaging plays a key role in the management of patients with cardiovascular diseases. It allows a combination of complementary anatomical, morphological and functional information, increases diagnosis accuracy, and improves the efficacy of cardiovascular interventions and clinical outcomes. Fully-automated processing and quantitative analysis of multi-modality cardiac images could have a direct impact on clinical research and evidence-based patient management. However, these require overcoming significant challenges including inter-modality misalignment and finding optimal methods to integrate information from different modalities. This paper aims to provide a comprehensive review of multi-modality imaging in cardiology, the computing methods, the validation strategies, the related clinical workflows and future perspectives. For the computing methodologies, we have a favored focus on the three tasks, i.e., registration, fusion and segmentation, which generally involve multi-modality imaging data, either combining information from different modalities or transferring information across modalities. The review highlights that multi-modality cardiac imaging data has the potential of wide applicability in the clinic, such as trans-aortic valve implantation guidance, myocardial viability assessment, and catheter ablation therapy and its patient selection. Nevertheless, many challenges remain unsolved, such as missing modality, modality selection, combination of imaging and non-imaging data, and uniform analysis and representation of different modalities. There is also work to do in defining how the well-developed techniques fit in clinical workflows and how much additional and relevant information they introduce. These problems are likely to continue to be an active field of research and the questions to be answered in the future.

Coronary Obstruction during Valve-in-Valve Transcatheter Aortic Valve Replacement: Pre-Procedural Risk Evaluation, Intra-Procedural Monitoring, and Follow-Up

Valve-in-valve (ViV) transcatheter aortic valve replacement (TAVR) is emerging as an effective treatment for patients with symptomatically failing bioprosthetic valves and a high prohibitive surgical risk; a longer life expectancy has led to a higher demand for these valve reinterventions due to the increased possibilities of outliving the bioprosthetic valve's durability. Coronary obstruction is the most feared complication of valve-in-valve (ViV) TAVR; it is a rare but life-threatening complication and occurs most frequently at the left coronary artery ostium. Accurate pre-procedural planning, mainly based on cardiac computed tomography, is crucial to determining the feasibility of a ViV TAVR and to assessing the anticipated risk of a coronary obstruction and the eventual need for coronary protection measures. Intraprocedurally, the aortic root and a selective coronary angiography are useful for evaluating the anatomic relationship between the aortic valve and coronary ostia; transesophageal echocardiographic real-time monitoring of the coronary flow with a color Doppler and pulsed-wave Doppler is a valuable tool that allows for a determination of real-time coronary patency and the detection of asymptomatic coronary obstructions. Because of the risk of developing a delayed coronary obstruction, the close postprocedural monitoring of patients at a high risk of developing coronary obstructions is advisable. CT simulations of ViV TAVR, 3D printing models, and fusion imaging represent the future directions that may help provide a personalized lifetime strategy and tailored approach for each patient, potentially minimizing complications and improving outcomes.

Computed tomography angiography/magnetic resonance imaging-based preprocedural planning and guidance in the interventional treatment of structural heart disease

Preprocedural planning and periprocedural guidance based on image fusion are widely established techniques supporting the interventional treatment of structural heart disease. However, these two techniques are typically used independently. Previous works have already demonstrated the benefits of integrating planning details into image fusion but are limited to a few applications and the availability of the proprietary tools used. We propose a vendor-independent approach to integrate planning details into periprocedural image fusion facilitating guidance during interventional treatment. In this work, we demonstrate the feasibility of integrating planning details derived from computer tomography and magnetic resonance imaging into periprocedural image fusion with open-source and commercially established tools. The integration of preprocedural planning details into periprocedural image fusion has the potential to support safe and efficient interventional treatment of structural heart disease.

CT in Transcatheter-delivered Treatment of Valvular Heart Disease

Minimally invasive strategies to treat valvular heart disease have emerged over the past 2 decades. The use of transcatheter aortic valve replacement in the treatment of severe aortic stenosis, for example, has recently expanded from high- to low-risk patients and became an alternative treatment for those with prohibitive surgical risk. With the increase in transcatheter strategies, multimodality imaging, including echocardiography, CT, fluoroscopy, and cardiac MRI, are used. Strategies for preprocedural imaging strategies vary depending on the targeted valve. Herein, an overview of preprocedural imaging strategies and their postprocessing approaches is provided, with a focus on CT. Transcatheter aortic valve replacement is reviewed, as well as less established minimally invasive treatments of the mitral and tricuspid valves. In addition, device-specific details and the goals of CT imaging are discussed. Future imaging developments, such as peri-procedural fusion imaging, machine learning for image processing, and mixed reality applications, are presented.

Three-Dimensional Virtual and Printed Prototypes in Complex Congenital and Pediatric Cardiac Surgery-A Multidisciplinary Team-Learning Experience

Three-dimensional (3D) virtual modeling and printing advances individualized medicine and surgery. In congenital cardiac surgery, 3D virtual models and printed prototypes offer advantages of better understanding of complex anatomy, hands-on preoperative surgical planning and emulation, and improved communication within the multidisciplinary team and to patients. We report our single center team-learning experience about the realization and validation of possible clinical benefits of 3D-printed models in surgical planning of complex congenital cardiac surgery. CT-angiography raw data were segmented into 3D-virtual models of the heart-great vessels. Prototypes were 3D-printed as rigid “blood-volume” and flexible “hollow”. The accuracy of the models was evaluated intraoperatively. Production steps were realized in the framework of a clinical/research partnership. We produced 3D prototypes of the heart-great vessels for 15 case scenarios (nine males, median age: 11 months) undergoing complex intracardiac repairs. Parity between 3D models and intraoperative structures was within 1 mm range. Models refined diagnostics in 13/15, provided new anatomic information in 9/15. As a team-learning experience, all complex staged redo-operations (13/15; Aristotle-score mean: 10.64 ± 1.95) were rehearsed on the 3D models preoperatively. 3D-printed prototypes significantly contributed to an improved/alternative operative plan on the surgical approach, modification of intracardiac repair in 13/15. No operative morbidity/mortality occurred. Our clinical/research partnership provided coverage for the extra time/labor and material/machinery not financed by insurance. 3D-printed models provided a team-learning experience and contributed to the safety of complex congenital cardiac surgeries. A clinical/research partnership may open avenues for bioprinting of patient-specific implants.

Real-time echocardiography-fluoroscopy fusion imaging for left atrial appendage closure: prime time for fusion imaging?

BACKGROUND

Real-time echocardiography-fluoroscopy fusion imaging (FI) merges real-time echocardiographic imaging with fluoroscopic images allowing intuitive anatomical spatial orientation during structural heart disease interventions. We aimed to assess the safety and efficacy of FI during percutaneous left atrial appendage closure (LAAC).

METHODS

34 consecutive patients before (-FI) and 121 patients after (+FI) the introduction of FI for LAAC were included in a single-centre study. In-hospital safety parameters were analysed according to adverse event (AE) definition of the Munich consensus document and procedure-related parameters were assessed for efficacy. An ANCOVA was performed to investigate the influence of a learning curve.

RESULTS

Time until successful transseptal puncture was significantly reduced as well as total procedure time and the amount of contrast agent used (+FI/-FI:17 ± 6.35 min vs. 22 ± 8.33 min, p = 0.001; +FI/-FI: 50 min IQR 43 min - 60 min vs. 57 min IQR 45 min -70 min; p = 0.013; +FI/-FI: 70 mL, IQR 55 ml-90 mL vs. 152 mL, IQR 107 mL - 205 mL; p < 0.001). However, fluoroscopy time and dose-area product did not differ between both groups. There was no significant difference in the occurrence of in-hospital adverse events (+FI/-FI: 2.5% vs. 0%; p = 0.596). The ANCOVA revealed that the learning curve does not affect procedural efficacy parameters such as procedure time, time to transseptal puncture, amount of contrast agent and dose-area product.

CONCLUSIONS

FI for LAAC reduces the total procedure time, the time to successful transseptal puncture and periprocedural amount of contrast agent.

Image fusion of integrating fluoroscopy into 3D computed tomography in guidance of left atrial appendage closure

AIMS

We evaluated the feasibility of left atrial appendage (LAA) closure guided by the image fusion of integrating fluoroscopy into 3D computed tomography (CT).

METHODS AND RESULTS

A total of 117 consecutive patients who underwent LAA closure with or without the image fusion were matched (1:2). Each LAA closure step of the Image fusion group was guided by the preprocedure CT and image fusion, especially in the plan of LAA measurement and transseptal puncture. All patients were successfully implanted with a WATCHMAN closure device. Comparing the two groups, the mean number of recapture times and the number of devices per patient of the Image fusion group were significantly lower (0.4 ± 0.5 vs. 0.7 ± 0.8, P = 0.031 and 1.0 ± 0.2 vs. 1.1 ± 0.3, P = 0.027, respectively). The one-time successful deployment rate by the support of the image fusion was higher than in the control group (66.7% vs. 44.9%, P = 0.026). Each case of the Image fusion group was completely occluded with one transseptal puncture, while five of the Non-image fusion group required redo transseptal punctures. During the 45-day follow-up, both group cases presented occlusion efficiency and no major adverse cardiac events were observed.

CONCLUSION

Image fusion technique integrating fluoroscopy into the 3D CT is safe and feasible which can be easily incorporated into the procedural work-flow of percutaneous LAA closure. The fusion image can play an important alternative role in the plan of LAA measurement and transseptal puncture site for improving the LAA closure procedure.

Comparison of skin dose calculated by the dose tracking system (DTS) with a beam angular correction factor and that calculated by Monte-Carlo

Skin dose is dependent on the incident beam angle and corrections are needed for accurate estimation of the risk of deterministic effects of the skin. Angular-correction factors (ACF) were calculated and incorporated into our skin-dose-tracking system (DTS) and the results compared to Monte-Carlo simulations for a neuro-interventional procedure. To obtain the ACF's, EGSnrc Monte-Carlo (MC) software was used to calculate the dose averaged over 0.5, 1, 2, 3, 4 and 5 mm depth into the entrance surface of a water phantom at the center of the field as a function of incident beam to skin angle from 90-10 degrees for beam field sizes from 5-15 cm and for beam energies from 60-120 kVp. These values were normalized to the incident primary dose to obtain the ACF. The angle of incidence at each mesh vertex in the beam on the surface of the DTS patient graphic was calculated as the complement of the angle between the normal vector and the vector of the intersecting ray from the tube focal spot; skin dose at that vertex was calculated using the corresponding ACF. The skin-dose values with angular correction were compared to those calculated using MC with a matching voxelized phantom. The results show the ACF decreases with decreasing incident angle and skin thickness, and increases with increasing field size and kVp. Good agreement was obtained between the skin dose calculated by the angular-corrected DTS and MC, while use of the ACF allows the real-time performance of the DTS to be maintained.

Systematic Fluoroscopic-Echocardiographic Fusion Imaging Protocol for Transcatheter Edge-to-Edge Mitral Valve Repair Intraprocedural Monitoring

BACKGROUND

Whether fluoroscopic-echocardiographic fusion imaging (FI) might offer added value for intraprocedural guidance during transcatheter edge-to-edge mitral valve repair is yet unknown, and few data exist regarding the safety and feasibility of this novel technology.

METHODS

The aim of this single-center study was to test and validate a FI protocol for intraprocedural monitoring of transcatheter edge-to-edge mitral valve repair and assess its clinical usefulness. Eighty patients underwent MitraClip implantation using FI guidance (FI+) for either degenerative (35%) or functional (65%) mitral regurgitation and were compared with the last 80 patients before FI introduction, treated using conventional echocardiography and fluoroscopic monitoring (FI-).

RESULTS

The number of patients treated for functional and degenerative mitral regurgitation was similar between the FI+ and FI- groups, as well as the number of devices implanted (1.51 ± 0.5 vs 1.58 ± 0.6, P = .46). The prevalence of complex mitral anatomy for percutaneous repair was high (32.5%, up to 39.2% in the hybrid arm). Fluoroscopy time was significantly lower in FI+ patients (37.3 ± 14.6 vs 48.3 ± 28.3 min, P = .003), but not kerma area product (91.5 ± 74.1 vs 108.8 ± 105.0 Gy · cm², P = .23) or procedural time (92.2 ± 36.1 vs 103.1 ± 42.7 min, P = .086). After adjusting for confounding factors (MitraClip XT device and complex anatomy), FI reduced fluoroscopy time (coefficient = -10.4 min; 95% CI, -18.03 to -2.82; P = .007) and improved procedural success at the end of the procedure (odds ratio, 2.87; 95% CI, 1.00 to 8.24; P = .049) and discharge (odds ratio, 2.24; 95% CI, 1.04 to 4.80; P = .039). Rates of periprocedural complications were similar in both groups (8.9% vs 13.0%, P = .40).

CONCLUSIONS

The authors describe the systematic use of an FI protocol for intraprocedural guidance during transcatheter edge-to-edge mitral valve repair, demonstrating a reduction in fluoroscopy time and an improvement in procedural success in a population with a high prevalence of challenging mitral anatomy for percutaneous repair.

A guide for pre-procedural imaging for transcatheter aortic valve replacement patients

Safe and accurate pre-procedural assessment of cardiovascular anatomy, physiology, and pathophysiology prior to TAVR procedures can mean the difference between success and catastrophic failure. It is imperative that clinical care team members share a basic understanding of the preprocedural imaging technologies available for optimizing the care of TAVR patients. Herein, we review current imaging technology for assessing the anatomy, physiology, and pathophysiology of the aortic valvular complex, ventricular function, and peripheral vasculature, including echocardiography, cardiac catheterization, cardiac computed tomography, and cardiac magnetic resonance prior to a TAVR procedure. The authorship includes cardiac-trained anesthesiologists, anesthesiologists with expertise in pre-procedural cardiac assessment and optimization, and interventional cardiologists with expertise in cardiovascular imaging prior to TAVRs. Improving the understanding of all team members will undoubtedly translate into safer, more coordinated patient care.

Fusion imaging in interventional cardiology

The number and complexity of percutaneous interventions for the treatment of structural heart disease has increased in clinical practice in parallel with the development of new imaging technologies, in order to render these interventions safer and more accurate. Complementary imaging modalities are commonly used, but they require additional mental reconstruction and effort by the interventional team. The concept of fusion imaging, where two different modalities are fused in real time and on a single monitor, aims to solve these limitations. This is an important tool to guide percutaneous interventions, enabling a good visualization of catheters, guidewires and devices employed, with enhanced spatial resolution and anatomical definition. It also allows the marking of anatomical reference points of interest for the procedure. Some studies show decreased procedural time and total radiation dose with fusion imaging; however, there is a need to obtain data with more robust scientific methodology to assess the impact of this technology in clinical practice. The aim of this review is to describe the concept and basic principles of fusion imaging, its main clinical applications and some considerations about the promising future of this imaging technology.

TAVR-related echocardiographic assessment - status quo, challenges and perspectives

Transcatheter aortic valve replacement (TAVR) is an emerging and a well-established procedure for high-risk and inoperable patients worldwide. Recent studies revealed furthermore that TAVR is equal or even superior to surgical valve replacement in intermediate risk patients. Therefore, a successful procedure is not only dependent on precise preprocedural patient selection but also on careful intraprocedural multimodal imaging guidance and adequate postprocedural follow-up. Up to date, 2D/3D transthoracic and/or transoesophageal echocardiography is an easy and goal-oriented tool for periprocedural TAVR-assessment regarding annulus measurements, cardiac function and concomitant valve diseases. Further procedural success is directly related to prevention of severe early and late complications. Thus, a careful intra- and postprocedural echocardiographic guidance is crucial to evaluate prosthetic function, position and its haemodynamic implication and changes in the integrity of the left ventricle during intra- and postprocedural management. We explored the role of echocardiography for pre-, intra- and postprocedural TAVR-assessment, illustrated by cases and possible algorithms, in a comprehensive literature review. Furthermore, we describe the role of fusion imaging, that is, real-time fusion of transoesophageal echocardiography and fluoroscopy (EchoNavigator Release System^® I and II) during TAVR.

Transesophageal echocardiography complications associated with interventional cardiology procedures

BACKGROUND

Although there have been several reports documenting complications related with transesophageal echocardiography (TEE) manipulation following cardiac surgery, there is a paucity of data regarding the safety of TEE used to guide catheter-based interventions. The aim of this study was to determine the prevalence, types and risk factors of complications associated with procedures requiring active TEE guidance.

METHODS

This study included 1249 consecutive patients undergoing either transcatheter aortic valve implantation (TAVI), Mitraclip, left atrial appendage occlusion (LAAO) or paravalvular leak closure (PVLC). Patients were divided into 2 cohorts based on the degree of probe manipulation required to guide the procedure and the risk of developing a TEE-related complication: low-risk (TAVI, n = 1037) and high-risk (Mitraclip, LAAO and PVLC, n = 212). Patients were further analyzed according to the occurrence of major and minor TEE-related complications.

RESULTS

The overall incidence of TEE-related complications was 0.9% in the TAVI group and 6.1% in the rest of the cohort (P < .001). Patients in the high-risk cohort had also a higher incidence of major-complications (2.8% vs 0.6%, P = .008), and factors associated with an increased risk were being underweight, having a prior history of gastrointestinal bleeding and the use of chronic steroids/immunosuppressive medications. Procedural time under TEE-manipulation was longer in patients exhibiting complications and was an independent predictor of major complications (OR = 1.13, 95% CI 1.01-1.25, for each 10 minutes increments in imaging time). Patients with major complications undergoing Mitraclip had the longest median time under TEE-manipulation (297 minutes) and a risk of developing a major-complication that was 10.64 times higher than the rest of the cohort (95% CI 3.30-34.29, P < .001).

CONCLUSION

The prevalence of TEE-related complications associated with interventional procedures is higher than previously reported. Undergoing a prolonged procedure, particularly in the setting of Mitraclip, was the main factor linked to TEE-related complications.

EDUCATIONAL SERIES IN CONGENITAL HEART DISEASE: Three-dimensional echocardiography in congenital heart disease

Three-dimensional echocardiography is a valuable tool for the assessment of cardiac function where it permits calculation of chamber volume and function. The anatomy of valvar and septal structures can be presented in unique and intuitive ways to enhance surgical planning. Guidance of interventional procedures using the technique has now become established in many clinical settings. Enhancements of image processing to include intracavity flow, image fusion and true 3D displays look set to further improve the contribution of this modality to care of the patient with congenital heart disease.

Virtual museum of congenital heart defects: digitization and establishment of a database for cardiac specimens

Education and training of morphology for medical students, and professionals specializing in pediatric cardiology and surgery has traditionally been based on hands-on encounter with congenitally malformed cardiac specimens. Large international archives are no longer widely available due to stricter data protection rules, a reduced number of autopsies, attrition rate of existing specimens, and most importantly due to a higher survival rate of patients. Our Cardiac Archive houses about 400 cardiac specimens with congenital heart disease. The collection spans almost 60 years and thus goes back to pre-surgical era. Unfortunately, attrition rate due to desiccation has led to an increased natural decay in recent years. The present multi-institutional project focuses on saving the collection by digitization. Specimens are scanned by high-resolution micro-CT/MRI. Virtual 3D-models are segmented and a comprehensive database is built. We now report an initial feasibility study with six test specimens that provided promising results, however, adequate presentation of the intracardiac anatomy, including septa and cardiac valves requires further refinements. Computer assisted design methods are necessary to overcome consequences of pathological examination, shrinkage and/or distortion of the specimens. For a next step, we anticipate an expandable web-based virtual museum with interactive reference and training tools. Web access for professional third parties will be provided by registration/subscription. In a future phase, segmental wall motion data could be added to virtual models. 3D-printed models may replace actual specimens and serve as hands-on surgical training to elucidate complex morphologies, promote surgical emulation, and extract more accurate procedural knowledge based on such a collection.

Preprocedural planning of transcatheter mitral valve interventions by multidetector CT: What the radiologist needs to know

Mitral regurgitation is the most common valve disorder in the Western world, and although surgery is the established therapeutic gold standard, percutaneous transcatheter mitral interventions are gaining acceptance in selected patients who are inoperable or at an exceedingly high surgical risk. For such patients, multidetector computed tomography (MDCT) can provide a wealth of valuable morphological and functional information in the preoperative setting. Our aim is to give an overview of the MDCT image acquisition protocols, post-processing techniques, and imaging findings with which radiologists should be familiar to convey all relevant information to the Heart Team for successful treatment planning.

Three-dimensional modelling and three-dimensional printing in pediatric and congenital cardiac surgery

Three-dimensional (3D) modelling and printing methods greatly support advances in individualized medicine and surgery. In pediatric and congenital cardiac surgery, personalized imaging and 3D modelling presents with a range of advantages, e.g., better understanding of complex anatomy, interactivity and hands-on approach, possibility for preoperative surgical planning and virtual surgery, ability to assess expected results, and improved communication within the multidisciplinary team and with patients. 3D virtual and printed models often add important new anatomical findings and prompt alternative operative scenarios. For the lack of critical mass of evidence, controlled randomized trials, however, most of these general benefits remain anecdotal. For an individual surgical case-scenario, prior knowledge, preparedness and possibility of emulation are indispensable in raising patient-safety. It is advocated that added value of 3D printing in healthcare could be raised by establishment of a multidisciplinary centre of excellence (COE). Policymakers, research scientists, clinicians, as well as health care financers and local entrepreneurs should cooperate and communicate along a legal framework and established scientific guidelines for the clinical benefit of patients, and towards financial sustainability. It is expected that besides the proven utility of 3D printed patient-specific anatomical models, 3D printing will have a major role in pediatric and congenital cardiac surgery by providing individually customized implants and prostheses, especially in combination with evolving techniques of bioprinting.

An MR-Based Model for Cardio-Respiratory Motion Compensation of Overlays in X-Ray Fluoroscopy

In X-ray fluoroscopy, static overlays are used to visualize soft tissue. We propose a system for cardiac and respiratory motion compensation of these overlays. It consists of a 3-D motion model created from real-time magnetic resonance (MR) imaging. Multiple sagittal slices are acquired and retrospectively stacked to consistent 3-D volumes. Slice stacking considers cardiac information derived from the ECG and respiratory information extracted from the images. Additionally, temporal smoothness of the stacking is enhanced. Motion is estimated from the MR volumes using deformable 3-D/3-D registration. The motion model itself is a linear direct correspondence model using the same surrogate signals as slice stacking. In X-ray fluoroscopy, only the surrogate signals need to be extracted to apply the motion model and animate the overlay in real time. For evaluation, points are manually annotated in oblique MR slices and in contrast-enhanced X-ray images. The 2-D Euclidean distance of these points is reduced from 3.85 to 2.75 mm in MR and from 3.0 to 1.8 mm in X-ray compared with the static baseline. Furthermore, the motion-compensated overlays are shown qualitatively as images and videos.

Interventional dual-energy imaging-Feasibility of rapid kV-switching on a C-arm CT system

PURPOSE

In the last years, dual-energy CT imaging has shown clinical value, thanks to its ability to differentiate materials based on their atomic number and to exploit different properties of images acquired at two different energies. C-arm CT systems are used to guide procedures in the interventional suite. Until now, there are no commercially available systems that employ dual-energy material decomposition. This paper explores the feasibility of implementing a fast kV-switching technique on a clinically available angiographic system for acquiring dual-energy C-arm CT images.

METHODS

As an initial proof of concept, a fast kV-switching approach was implemented on an angiographic C-arm system and the peak tube voltage during 3D rotational scans was measured. The tube voltage measurements during fast kV-switching scans were compared to corresponding measurements on kV-constant scans. Additionally, to prove stability of the requested exposure parameters, the accuracy of the delivered tube current and pulse width were also recorded and compared. In a first phantom experiment, the voxel intensity values of the individual tube voltage components of the fast kV-switching scans were compared to their corresponding kV-constant scans. The same phantom was used for a simple material decomposition between different iodine concentrations and pure water using a fast kV-switching protocol of 81 and 125 kV. In the last experiment, the same kV-switching protocol as in the phantom scan was used in an in vivo pig study to demonstrate the clinical feasibility.

RESULTS

During rapid kV-switching acquisitions, the measured tube voltage of the x-ray tube during fast switching scans has an absolute deviation of 0.23 ± 0.13 kV compared to the measured tube voltage produced during kV-constant acquisitions. The stability of the peak tube voltage over different scan requests was about 0.10 kV for the low and 0.46 for the high energy kV-switching scans and less than 0.1 kV for kV-constant scans, indicating slightly lower stability for kV-switching scans. The tube current resulted in a relative deviation of -1.6% for the low and 6.6% overestimation for the high tube voltage of the kV-switching scans compared to the kV-constant scans. The pulse width showed no deviation for the longer pulse width and only minor deviations (0.02 ± 0.02 ms) for the shorter pulse widths compared to the kV-constant scans. The phantom experiment using different iodine concentrations showed an accurate correlation (R² > 0.99) between the extracted intensity values in the kV-switching and kV-constant reconstructed volumes, and allows for an automatic differentiation between contrast concentration down to 10% (350 mg/ml iodine) and pure water under low-noise conditions. Preliminary results of iodine and soft tissue separation showed also promising results in the first in vivo pig study.

CONCLUSIONS

The feasibility of dual-energy imaging using a fast kV-switching method on an angiographic C-arm CT system was investigated. Direct measurements of beam quality in the x-ray field demonstrate the stability of the kV-switching method. Phantom and in vivo experiments showed that images did not deviate from those of corresponding kV-constant scans. All performed experiments confirmed the capability of performing fast kV-switching scans on a clinically available C-arm CT system. More complex material decomposition tasks and postprocessing steps will be part of future investigations.

Safety and efficacy of transseptal puncture guided by real-time fusion of echocardiography and fluoroscopy

Aims

Visual guidance through echocardiography and fluoroscopy is crucial for a successful transseptal puncture (TSP) in a prespecified region of the fossa ovalis. The novel EchoNavigator system Release II (EchoNav II, Philips Healthcare, Andover, Massachusetts, USA) enables the real-time fusion of fluoroscopic and echocardiographic images. We evaluated this new imaging method in respect to safety and efficacy of TSP during MitraClip implantation and left atrial appendage closure.

Methods

Forty-four patients before (−EchoNav) and 44 patients after (+EchoNav) the introduction of real-time fusion were included in our retrospective, single-centre study. The primary endpoint was the occurrence of adverse events due to TSP. Secondary endpoints were successful puncture at the prespecified region and time until TSP (min).

Results

In both groups TSP was performed successfully in the prespecified region and no adverse events occurred during or due to the accomplishment of TSP. Time until TSP was significantly reduced in the +EchoNav group in comparison with the EchoNav group (18.48 ± 5.62 min vs. 23.20 ± 9.61 min, p = 0.006).

Conclusions

Real-time fusion of echocardiography and fluoroscopy proved to be as safe and successful as standard best practice for TSP. Moreover, efficacy was improved through significant reduction of time until TSP.

Percutaneous Closure of Paravalvular Leaks: A Systematic Review

Paravalvular leak (PVL) is an uncommon yet serious complication associated with the implantation of mechanical or bioprosthetic surgical valves and more recently recognized with transcatheter aortic valves implantation (TAVI). A significant number of patients will present with symptoms of congestive heart failure or haemolytic anaemia due to PVL and need further surgical or percutaneous treatment. Until recently, surgery has been the only available therapy for the treatment of clinically significant PVLs despite the significant morbidity and mortality associated with re-operation. Percutaneous treatment of PVLs has emerged as a safe and less invasive alternative, with low complication rates and high technical and clinical success rates. However, it is a complex procedure, which needs to be performed by an experienced team of interventional cardiologists and echocardiographers. This review discusses the current understanding of PVLs, including the utility of imaging techniques in PVL diagnosis and treatment, and the principles, outcomes and complications of transcatheter therapy of PVLs.

Feasibility and Safety of Using a Fused Echocardiography/Fluoroscopy Imaging System in Patients with Congenital Heart Disease

BACKGROUND

Fused real-time three-dimensional transesophageal echocardiography and fluoroscopy has been used in adult patients during percutaneous mitral valve and aortic valve procedures. The use of fused echocardiographic/x-ray fluoroscopic imaging (FEX) in pediatric patients undergoing congenital heart disease catheterization has not been evaluated for feasibility and safety. The aims of this study were to assess the feasibility and safety of FEX for interventional guidance and to perform a comparison of atrial septal defect (ASD) device closure using this technology with traditional guidance methods.

METHODS

Prospective evaluation of FEX in congenital cardiac interventions was conducted. A subset of patients with ASD closures were compared with patients with historical ASD closures with and without FEX. The interventionalist and echocardiographer rated the anatomic quality of the fusion imaging as (1) excellent, (2) good, or (3) poor. In addition, the utility of FEX procedural guidance was graded as (1) superior, (2) no added benefit, or (3) inferior to that of standard guidance by fluoroscopy and transesophageal echocardiography.

RESULTS

FEX was successfully used in 26 procedures on 25 patients with congenital heart disease from January 2013 to February 2015. The median age was 9 years (range, 3-26 years), and the median weight was 29 kg (range, 16-77 kg). Twenty-six procedures were performed, including ASD closure, Fontan fenestration closure, and transcatheter valve placement in the tricuspid valve position. There was reduced fluoroscopy time and radiation dose in patients with ASDs who underwent imaging using this new technology (P < .001 and P < .03, respectively). There were no statistically significant differences in procedural times between the two groups. Anatomic definition was rated as excellent in 20 of 26 procedures, with the remaining six rated was good. Twenty-one of 26 procedures were graded as superior (81%), and five of 26 (19%) were graded as providing no added benefit. There were no complications in any of the procedures.

CONCLUSIONS

In this early experience, FEX is feasible and safe in patients undergoing congenital heart disease catheterization and provides useful guidance in the majority of interventional procedures. There were relative reductions in fluoroscopy time and radiation dose with the use of FEX for ASD closure.

Hybrid Imaging in the Catheter Laboratory: Real-time Fusion of Echocardiography and Fluoroscopy During Percutaneous Structural Heart Disease Interventions

Percutaneous catheter-based techniques for the treatment of structural heart disease are becoming more complex, and current imaging techniques have limitations: while fluoroscopy gives poor visualisation of cardiac anatomical structures, echocardiography is limited in its ability to detect the position of catheters and devices. The EchoNavigator® (Philips) live image guidance tool is a novel system that integrates real-time echocardiography with fluoroscopic X-ray imaging, optimising the guidance and positioning of devices. Use of the EchoNavigator system facilitates improved understanding of anatomical structures while showing enhanced visualisation of catheter and device movements. Early clinical experience suggests that the technology is feasible and safe, and provides enhanced understanding of the relationship between soft tissue anatomy and catheter devices in structural heart disease. The use of the EchoNavigator system can improve the confidence of interventional cardiologists in the targeting and positioning of devices in percutaneous interventions in structural heart disease, and has the potential to reduce procedural time, reduce the dosage of contrast and radiation and increase safety in the performance of procedural steps.