Intervention for critical aortic stenosis in Hutchinson-Gilford progeria syndrome.

Hutchinson-Gilford Progeria Syndrome (HGPS) is an ultra-rare genetic premature aging disease that is historically fatal in teenage years, secondary to severe accelerated atherosclerosis. The only approved treatment is the farnesyltransferase inhibitor lonafarnib, which improves vascular structure and function, extending average untreated lifespan of 14.5 years by 4.3 years (30%). With this longer lifespan, calcific aortic stenosis (AS) was identified as an emerging critical risk factor for cardiac death in older patients. Intervention to relieve critical AS has the potential for immediate improvement in healthspan and lifespan. However, HGPS patient-device size mismatch, pervasive peripheral arterial disease, skin and bone abnormalities, and lifelong failure to thrive present unique challenges to intervention. An international group of experts in HGPS, pediatric and adult cardiology, cardiac surgery, and pediatric critical care convened to identify strategies for successful treatment. Candidate procedures were evaluated by in-depth examination of 4 cases that typify HGPS clinical pathology. Modified transcatheter aortic valve replacement (TAVR) and left ventricular Apico-Aortic Conduit (AAC) placement were deemed high risk but viable options. Two cases received TAVR and 2 received AAC post-summit. Three were successful and 1 patient died perioperatively due to cardiovascular disease severity, highlighting the importance of intervention timing and comparative risk stratification. These breakthrough interventions for treating critical aortic stenosis in HGPS patients could rewrite the current clinical perspective on disease course by greatly improving late-stage quality of life and increasing lifespan. Expanding worldwide medical and surgical competency for this ultra-rare disease through expert information-sharing could have high impact on treatment success.

Differential Effects of Pharmacologic and Mechanical Support on Right-Left Ventricular Coupling.

BACKGROUND: Percutaneous ventricular assist devices are increasingly relied on to maintain perfusion for cardiogenic shock patients. Optimal medical management strategies however remain uncertain from limited understanding of interventricular effects. This study analyzed the effects of pharmacologic and left-sided mechanical support on right ventricular function. METHODS: A porcine model was developed to assess biventricular function during bolus pharmacologic administration before and after left-sided percutaneous ventricular assist and in cardiogenic shock. RESULTS: The presence of mechanical support increased right ventricular load and stress with respect to the left ventricle. This shifted and exaggerated the relative effects of commonly used vasoactive agents. Furthermore, induction of cardiogenic shock led to differential pulmonary vascular and right ventricular responses. CONCLUSIONS: Left ventricular ischemia and mechanical support altered interventricular coupling. Resulting impacts of pharmacologic agents indicate differential right heart responses and sensitivity to treatments and the need for further study to optimize biventricular function in shock patients.

Steady Flow Left Ventricle Unloading Is Superior to Pulsatile Pressure Augmentation Venting During Venoarterial Extracorporeal Membrane Oxygenation Support.

Venoarterial extracorporeal membrane oxygenation (VA-ECMO) shunts venous blood to the systemic arterial circulation to provide end-organ perfusion while increasing afterload that may impede left ventricle (LV) ejection and impair cardiac recovery. To maintain flow across the aortic valve and reduce risk of lethal clot formation, secondary mechanical circulatory support (MCS) devices are increasingly used despite limited understanding of their effects on cardiac function. This study sought to quantify the effects of VA-ECMO and combined with either intraaortic balloon pump (IABP) or percutaneous ventricular assist device (pVAD) on LV physiologic state and perfusion metrics in a porcine model of acute cardiogenic shock. Shock was induced through serial left anterior descending artery microbead embolization followed by initiation of VA-ECMO support and then placement of either IABP or pVAD. Hemodynamic measurements, LV pressure-volume loops, and carotid artery blood flow were evaluated before and after institution of combined MCS. The IABP decreased LV end-diastolic pressure by a peak of 15% while slightly increasing LV stroke work compared with decreases of more than 60% and 50% with the pVAD, respectively. The pVAD also demonstrated increased coronary perfusion and systemic pressure gradients in comparison to the IABP. Combined support with VA-ECMO and pVAD improves cardiovascular state in comparison to IABP.

Dynamic load modulation predicts right heart tolerance of left ventricular cardiovascular assist in a porcine model of cardiogenic shock.

Ventricular assist devices (VADs) offer mechanical support for patients with cardiogenic shock by unloading the impaired ventricle and increasing cardiac outflow and subsequent tissue perfusion. Their ability to adjust ventricular assistance allows for rapid and safe dynamic changes in cardiac load, which can be used with direct measures of chamber pressures to quantify cardiac pathophysiologic state, predict response to interventions, and unmask vulnerabilities such as limitations of left-sided support efficacy due to intolerance of the right heart. We defined hemodynamic metrics in five pigs with dynamic peripheral transvalvular VAD (pVAD) support to the left ventricle. Metrics were obtained across a spectrum of disease states, including left ventricular ischemia induced by titrated microembolization of a coronary artery and right ventricular strain induced by titrated microembolization of the pulmonary arteries. A sweep of different pVAD speeds confirmed mechanisms of right heart decompensation after left-sided support and revealed intolerance. In contrast to the systemic circulation, pulmonary vascular compliance dominated in the right heart and defined the ability of the right heart to adapt to left-sided pVAD unloading. We developed a clinically accessible metric to measure pulmonary vascular compliance at different pVAD speeds that could predict right heart efficiency and tolerance to left-sided pVAD support. Findings in swine were validated with retrospective hemodynamic data from eight patients on pVAD support. This methodology and metric could be used to track right heart tolerance, predict decompensation before right heart failure, and guide titration of device speed and the need for biventricular support.

A transformer-based pyramid network for coronary calcified plaque segmentation in intravascular optical coherence tomography images.

Characterizing coronary calcified plaque (CCP) provides essential insight into diagnosis and treatment of atherosclerosis. Intravascular optical coherence tomography (OCT) offers significant advantages for detecting CCP and even automated segmentation with recent advances in deep learning techniques. Most of current methods have achieved promising results by adopting existing convolution neural networks (CNNs) in computer vision domain. However, their performance can be detrimentally affected by unseen plaque patterns and artifacts due to inherent limitation of CNNs in contextual reasoning. To overcome this obstacle, we proposed a Transformer-based pyramid network called AFS-TPNet for robust, end-to-end segmentation of CCP from OCT images. Its encoder is built upon CSWin Transformer architecture, allowing for better perceptual understanding of calcified arteries at a higher semantic level. Specifically, an augmented feature split (AFS) module and residual convolutional position encoding (RCPE) mechanism are designed to effectively enhance the capability of Transformer in capturing both fine-grained features and global contexts. Extensive experiments showed that AFS-TPNet trained using Lovasz Loss achieved superior performance in segmentation CCP under various contexts, surpassing prior state-of-the-art CNN and Transformer architectures by more than 6.58% intersection over union (IoU) score. The application of this promising method to extract CCP features is expected to enhance clinical intervention and translational research using OCT.

Single-Cell RNA Sequencing Reveals That Adaptation of Human Aortic Endothelial Cells to Antiproliferative Therapies Is Modulated by Flow-Induced Shear Stress.

BACKGROUND: Endothelial cells (ECs) are capable of quickly responding in a coordinated manner to a wide array of stresses to maintain vascular homeostasis. Loss of EC cellular adaptation may be a potential marker for cardiovascular disease and a predictor of poor response to endovascular pharmacological interventions such as drug-eluting stents. Here, we report single-cell transcriptional profiling of ECs exposed to multiple stimulus classes to evaluate EC adaptation. METHODS: Human aortic ECs were costimulated with both pathophysiological flows mimicking shear stress levels found in the human aorta (laminar and turbulent, ranging from 2.5 to 30 dynes/cm2) and clinically relevant antiproliferative drugs, namely paclitaxel and rapamycin. EC state in response to these stimuli was defined using single-cell RNA sequencing. RESULTS: We identified differentially expressed genes and inferred the TF (transcription factor) landscape modulated by flow shear stress using single-cell RNA sequencing. These flow-sensitive markers differentiated previously identified spatially distinct subpopulations of ECs in the murine aorta. Moreover, distinct transcriptional modules defined flow- and drug-responsive EC adaptation singly and in combination. Flow shear stress was the dominant driver of EC state, altering their response to pharmacological therapies. CONCLUSIONS: We showed that flow shear stress modulates the cellular capacity of ECs to respond to paclitaxel and rapamycin administration, suggesting that while responding to different flow patterns, ECs experience an impairment in their transcriptional adaptation to other stimuli.

CardioVision: A fully automated deep learning package for medical image segmentation and reconstruction generating digital twins for patients with aortic stenosis.

Aortic stenosis (AS) is the most prevalent heart valve disease in western countries that poses a significant public health challenge due to the lack of a medical treatment to prevent valve calcification. Given the aging population demographic, the prevalence of AS is projected to rise, resulting in a progressively significant healthcare and economic burden. While surgical aortic valve replacement (SAVR) has been the gold standard approach, the less invasive transcatheter aortic valve replacement (TAVR) is poised to become the dominant method for high- and medium-risk interventions. Computational simulations using patient-specific models, have opened new research avenues for optimizing emerging devices and predicting clinical outcomes. The traditional techniques of generating digital replicas of patients' aortic root, native valve, and calcification are time-consuming and labor-intensive processes requiring specialized tools and expertise in anatomy. Alternatively, deep learning models, such as the U-Net architecture, have emerged as reliable and fully automated methods for medical image segmentation. Two-dimensional U-Nets have been shown to produce comparable or more accurate results than trained clinicians' manual segmentation while significantly reducing computational costs. In this study, we have developed a fully automatic AI tool capable of reconstructing the digital twin geometry and analyzing the calcification distribution on the aortic valve. The developed automatic segmentation package enables the modeling of patient-specific anatomies, which can then be used to simulate virtual interventional procedures, optimize emerging prosthetic devices, and predict clinical outcomes.

Fully automated construction of three-dimensional finite element simulations from Optical Coherence Tomography.

Despite recent advances in diagnosis and treatment, atherosclerotic coronary artery diseases remain a leading cause of death worldwide. Various imaging modalities and metrics can detect lesions and predict patients at risk; however, identifying unstable lesions is still difficult. Current techniques cannot fully capture the complex morphology-modulated mechanical responses that affect plaque stability, leading to catastrophic failure and mute the benefit of device and drug interventions. Finite Element (FE) simulations utilizing intravascular imaging OCT (Optical Coherence Tomography) are effective in defining physiological stress distributions. However, creating 3D FE simulations of coronary arteries from OCT images is challenging to fully automate given OCT frame sparsity, limited material contrast, and restricted penetration depth. To address such limitations, we developed an algorithmic approach to automatically produce 3D FE-ready digital twins from labeled OCT images. The 3D models are anatomically faithful and recapitulate mechanically relevant tissue lesion components, automatically producing morphologies structurally similar to manually constructed models whilst including more minute details. A mesh convergence study highlighted the ability to reach stress and strain convergence with average errors of just 5.9% and 1.6% respectively in comparison to FE models with approximately twice the number of elements in areas of refinement. Such an automated procedure will enable analysis of large clinical cohorts at a previously unattainable scale and opens the possibility for in-silico methods for patient specific diagnoses and treatment planning for coronary artery disease.

Histological examination of renal nerve distribution, density, and function in humans.

BACKGROUND: Renal denervation is optimised when guided by knowledge of nerve distribution. AIMS: We aimed to assess sympathetic nerve distribution along the renal arteries, especially in post-bifurcation vessel segments. METHODS: Renal arteries and surrounding tissue from 10 body donors were collected and examined histologically. Immunohistochemical staining was used to analyse nerve distribution and to identify afferent and efferent sympathetic nerves. RESULTS: A total of 6,781 nerves surrounding 18 renal arteries were evaluated. The mean lumen-nerve distance of the left renal artery (2.32±1.95 mm) was slightly greater than the right (2.29±2.03 mm; p=0.161); this varied across the arteries' courses: 3.7±2.3 mm in proximal segments, 2.5±2.0 mm in middle segments, 1.9±1.6 mm in distal prebifurcation segments and 1.3±1.0 mm in post-bifurcation segments (p<0.001). The number of nerves per quadrant was highest in the proximal segments (13.7±18.6), followed by the middle (9.7±7.9), distal prebifurcation (8.0±7.6), and distal post-bifurcation (4.3±4.0) segments (p<0.001). Circumferentially, the number of nerves was highest in the superior (7.8±9.4) and the ventral (7.6±13.1) quadrants (p=0.638). The mean tyrosine hydroxylase (TH) to calcitonin gene-related peptide (CGRP) ratio increased from proximal (37.5±33.5) to distal (72.0±7.2 in the post-bifurcation segments; p<0.001). Thirty-eight neuroganglia were identified along 14 (78%) renal arteries. CONCLUSIONS: Nerves converge to the renal arteries' lumen in the distal segments and along branches, resulting in the lowest number of nerves per quadrant and the shortest lumen-nerve distance in the distal post-bifurcation segments. Efferent nerves occur predominantly, and the ratio of efferent to afferent nerves continues to increase in the vessels' course.

Monocyte-endothelial cell interactions in vascular and tissue remodeling.

Monocytes are circulating leukocytes of innate immunity derived from the bone marrow that interact with endothelial cells under physiological or pathophysiological conditions to orchestrate inflammation, angiogenesis, or tissue remodeling. Monocytes are attracted by chemokines and specific receptors to precise areas in vessels or tissues and transdifferentiate into macrophages with tissue damage or infection. Adherent monocytes and infiltrated monocyte-derived macrophages locally release a myriad of cytokines, vasoactive agents, matrix metalloproteinases, and growth factors to induce vascular and tissue remodeling or for propagation of inflammatory responses. Infiltrated macrophages cooperate with tissue-resident macrophages during all the phases of tissue injury, repair, and regeneration. Substances released by infiltrated and resident macrophages serve not only to coordinate vessel and tissue growth but cellular interactions as well by attracting more circulating monocytes (e.g. MCP-1) and stimulating nearby endothelial cells (e.g. TNF-α) to expose monocyte adhesion molecules. Prolonged tissue accumulation and activation of infiltrated monocytes may result in alterations in extracellular matrix turnover, tissue functions, and vascular leakage. In this review, we highlight the link between interactions of infiltrating monocytes and endothelial cells to regulate vascular and tissue remodeling with a special focus on how these interactions contribute to pathophysiological conditions such as cardiovascular and chronic liver diseases.

RNF41 orchestrates macrophage-driven fibrosis resolution and hepatic regeneration.

Hepatic inflammation is a common trigger of chronic liver disease. Macrophage activation is a predictive parameter for survival in patients with cirrhosis. Ring finger protein 41 (RNF41) negatively regulates proinflammatory cytokines and receptors; however, the precise involvement of macrophage RNF41 in liver cirrhosis remains unknown. Here, we sought to understand how RNF41 dictates macrophage fate in hepatic fibrosis and repair within the inflammatory milieu. We found that RNF41 expression is down-regulated in CD11b+ macrophages recruited to mouse fibrotic liver and to patient cirrhotic liver regardless of cirrhosis etiology. Prolonged inflammation with TNF-α progressively reduced macrophage RNF41 expression. We designed a macrophage-selective gene therapy with dendrimer-graphite nanoparticles (DGNPs) to explore the influence of macrophage RNF41 restoration and depletion in liver fibrosis and regeneration. RNF41 expression induced in CD11b+ macrophages by DGNP-conjugated plasmids ameliorated liver fibrosis, reduced liver injury, and stimulated hepatic regeneration in fibrotic mice with or without hepatectomy. This therapeutic effect was mainly mediated by the induction of insulin-like growth factor 1. Conversely, depletion of macrophage RNF41 worsened inflammation, fibrosis, hepatic damage, and survival. Our data reveal implications of macrophage RNF41 in the control of hepatic inflammation, fibrosis, and regeneration and provide a rationale for therapeutic strategies in chronic liver disease and potentially other diseases characterized by inflammation and fibrosis.

The Natural History of Bicuspid Aortic Valve Disease.

The bicuspid aortic valve (BAV) is the most common congenital heart defect with an estimated prevalence of between 0.5% and 2% in the United States, representing up to 6.5 million individuals. Most individuals with BAV will develop valvular and/or aortic complications related to their BAV. How these various complications relate to one another and why they arise remain elusive. Yet, astute observations have yielded relevant classification systems that leverage valvular morphology, aortic shape, and genetic alteration patterns. Emerging evidence supports the existence of BAV phenotypes that may have different patterns of disease presentation, rates of progression, and risk of secondary complications. We review the natural history of BAV in light of known classification systems to illustrate a framework through which future hemodynamic, cell biologic, and other studies can better correlate with clinical endpoints. Consistent utilization of valvular, aortic, and genetic classification systems in the management and study of BAV may facilitate insight into the patterns of the disease, with prognostic and therapeutic significance for individuals who experience this common structural heart disease.

Interventional therapies for pulmonary embolism.

Pulmonary embolism (PE) is the leading cause of in-hospital death and the third most frequent cause of cardiovascular death. The clinical presentation of PE is variable, and choosing the appropriate treatment for individual patients can be challenging. Traditionally, treatment of PE has involved a choice of anticoagulation, thrombolysis or surgery; however, a range of percutaneous interventional technologies have been developed that are under investigation in patients with intermediate-high-risk or high-risk PE. These interventional technologies include catheter-directed thrombolysis (with or without ultrasound assistance), aspiration thrombectomy and combinations of the aforementioned principles. These interventional treatment options might lead to a more rapid improvement in right ventricular function and pulmonary and/or systemic haemodynamics in particular patients. However, evidence from randomized controlled trials on the safety and efficacy of these interventions compared with conservative therapies is lacking. In this Review, we discuss the underlying pathophysiology of PE, provide assistance with decision-making on patient selection and critically appraise the available clinical evidence on interventional, catheter-based approaches for PE treatment. Finally, we discuss future perspectives and unmet needs.

Moderate intensity exercise in pregnant patients with cardiovascular disease: A pilot study.

BACKGROUND: Exercise in pregnancy has proven health benefits, yet the safety of exercise in patients with pre-existing cardiovascular disease (CVD) has not been established. Our aim was to determine the feasibility and safety profile of moderate intensity exercise during pregnancy in patients with CVD, compared with those without CVD. METHODS: This is a prospective single center pilot study of a moderate intensity exercise regimen, with data collection through wearable fitness trackers and personal exercise logs in pregnant patients with and without pre-existing CVD. The primary outcome was Doppler umbilical artery systolic to diastolic (S/D) ratio measured between 32 and 34 weeks' gestation. The secondary outcomes were adverse maternal and fetal events, trends in wearable fitness tracker data, C-reactive protein levels, and weight changes. RESULTS: At baseline, the CVD group (62% congenital heart disease) took part in more prepregnancy walking, less weightlifting, and had a higher body mass index compared to the control group, and on average walked 539 fewer steps per day during pregnancy than the control group. Resting heart rate (HR) was found to increase in both groups up to 30 weeks' gestation. The cardiovascular disease group displayed an overall lower exercise intensity, as measured by the ability to increase HR with exercise over resting heart rate 1 hour prior to exercise at study baseline (45% vs 59% P < .001). Umbilical artery S/D ratio was normal in both groups. No differences were seen in adverse events between groups. CONCLUSIONS: This pilot study of moderate intensity exercise in pregnant individuals with pre-existing CVD demonstrated that patients with CVD were not able to increase their HR during exercise throughout pregnancy compared to those in the control group. Although a small study group, this data supports the hypothesis that exercise interventions during pregnancy for patients with CVD are feasible without evidence abnormal fetal Doppler profiles. Further studies using wearable fitness trackers may provide the opportunity to understand how to safely tailor exercise programs to pregnant individuals with CVD.

Optimization of 3D autologous chondrocyte-seeded polyglycolic acid scaffolds to mimic human ear cartilage.

Auricular reconstruction in children with microtia is one of the more complex procedures in plastic surgery. Obtaining sufficient native material to build an ear requires harvesting large fragments of rib cartilage in children. Herein, we investigated how to optimize autologous chondrocyte isolation, expansion and re-implantation using polyglycolic acid (PGA) scaffolds for generating enough cartilage to recapitulate a whole ear starting from a small ear biopsy. Ear chondrocytes isolated from human microtia subjects grew slower than microtia rib or healthy ear chondrocytes and displayed a phenotypic shift due to the passage number. Rabbit ear chondrocytes co-cultured with mesenchymal stem cells (MSC) at a 50 : 50 ratio recapitulated the cartilage biological properties in vitro. However, PGA scaffolds with different proportions of rabbit chondrocytes and MSC did not grow substantially in two months when subcutaneously implanted in immunosuppressed mice. In contrast, rabbit chondrocyte-seeded PGA scaffolds implanted in immunocompetent rabbits formed a cartilage 10 times larger than the original PGA scaffold. This cartilage mimicked the biofunctional and mechanical properties of an ear cartilage. These results indicate that autologous chondrocyte-seeded PGA scaffolds fabricated following our optimized procedure have immense potential as a solution for obtaining enough cartilage for auricular reconstruction and opens new avenues to redefine autologous cartilage replacement.

A new integrative approach to assess aortic stenosis burden and predict objective functional improvement after TAVR.

Background: A non-negligible rate of patients undergoing transcatheter aortic valve replacement (TAVR) do not report symptomatic improvement or even die in the short-midterm. We sought to assess the degree of objective functional recovery after TAVR and its prognostic implications and to develop a predictive model. Methods: In a cohort of patients undergoing TAVR, a prospective evaluation of clinical, anatomical, and physiological parameters was conducted before and after the procedure. These parameters were derived from echocardiography, non-invasive analysis of arterial pulse waves, and cardiac tomography. Objective functional improvement 6 months after TAVR was assessed using a 6-min walk test and nitro-terminal pro-brain natriuretic peptide (NT-proBNP) levels. The derived predictive model was prospectively validated in a different cohort. A clinical follow-up was conducted at 2 years. Results: Among the 212 patients included, objective functional improvement was observed in 169 patients (80%) and subjective improvement in 187 (88%). Patients with objective functional improvement showed a much lower death rate at 2 years (9% vs. 31% p = 0.0002). Independent predictors of improvement were as follows: mean aortic gradient of ≥40 mmHg, augmentation index75 of ≥45%, the posterior wall thickness of ≤12 mm, and absence of atrial fibrillation. A simple integer-based point score was developed (GAPA score), which showed an area under the curve of 0.81 for the overall cohort and 0.78 for the low-gradient subgroup. In a validation cohort of 216 patients, these values were 0.75 and 0.76, respectively. Conclusion: A total of 80% of patients experienced objective functional improvement after TAVR, showing a significantly lower 2-year mortality rate. A predictive score was built that showed a good discriminative performance in overall and low-gradient populations.

Substratum interactions modulate interplay between endothelial cell, epithelial cell, and fibroblast phenotype and immunomodulatory function.

Endothelial cells (ECs) sense and adapt to their environment, allowing them to display a range of functional phenotypes and promote vascular homeostasis across organ systems. However, many of these cues are lost when cells are cultured in vitro. This work explores how substratum interactions influence cellular phenotype. Culture conditions, specifically 2D culture on tissue culture polystyrene (TCP) versus 3D culture on collagen scaffolds, had a much greater effect on EC phenotype than did in vivo cell source. The 3D ECs responded to hypoxic gradients by inducing the expression of HIF1-a while 2D ECs underwent endothelial-to-mesenchymal transition. In comparing the effect of culture condition on EC phenotype and function to its effect on epithelial cells (EPs) and fibroblasts (FBs), it is evident that ECs are not simply vascular EPs but are unique in their response. For cell types like ECs, which are particularly responsive to their microenvironment, traditional culture on TCP is insufficient for revealing in vivo behavior. Further applying these findings, we found that culture-condition differentially affected the expression of immunomodulatory factors and in an in vivo model of allotransplantation, 3D culture reduced the cytotoxic response of host immune cells to all three cell types compared to 2D culture.

A soft robotic sleeve mimicking the haemodynamics and biomechanics of left ventricular pressure overload and aortic stenosis.

Preclinical models of aortic stenosis can induce left ventricular pressure overload and coarsely control the severity of aortic constriction. However, they do not recapitulate the haemodynamics and flow patterns associated with the disease. Here we report the development of a customizable soft robotic aortic sleeve that can mimic the haemodynamics and biomechanics of aortic stenosis. By allowing for the adjustment of actuation patterns and blood-flow dynamics, the robotic sleeve recapitulates clinically relevant haemodynamics in a porcine model of aortic stenosis, as we show via in vivo echocardiography and catheterization studies, and a combination of in vitro and computational analyses. Using in vivo and in vitro magnetic resonance imaging, we also quantified the four-dimensional blood-flow velocity profiles associated with the disease and with bicommissural and unicommissural defects re-created by the robotic sleeve. The design of the sleeve, which can be adjusted on the basis of computed tomography data, allows for the design of patient-specific devices that may guide clinical decisions and improve the management and treatment of patients with aortic stenosis.

Framework for lumen-based nonrigid tomographic coregistration of intravascular images.

Purpose: Modern medical imaging enables clinicians to effectively diagnose, monitor, and treat diseases. However, clinical decision-making often relies on combined evaluation of either longitudinal or disparate image sets, necessitating coregistration of multiple acquisitions. Promising coregistration techniques have been proposed; however, available methods predominantly rely on time-consuming manual alignments or nontrivial feature extraction with limited clinical applicability. Addressing these issues, we present a fully automated, robust, nonrigid registration method, allowing for coregistering of multimodal tomographic vascular image datasets using luminal annotation as the sole alignment feature. Approach: Registration is carried out by the use of the registration metrics defined exclusively for lumens shapes. The framework is primarily broken down into two sequential parts: longitudinal and rotational registration. Both techniques are inherently nonrigid in nature to compensate for motion and acquisition artifacts in tomographic images. Results: Performance was evaluated across multimodal intravascular datasets, as well as in longitudinal cases assessing pre-/postinterventional coronary images. Low registration error in both datasets highlights method utility, with longitudinal registration errors-evaluated throughout the paired tomographic sequences-of 0.29 ± 0.14 mm ( < 2 longitudinal image frames) and 0.18 ± 0.16 mm ( < 1 frame) for multimodal and interventional datasets, respectively. Angular registration for the interventional dataset rendered errors of 7.7 ° ± 6.7 ° , and 29.1 ° ± 23.2 ° for the multimodal set. Conclusions: Satisfactory results across datasets, along with additional attributes such as the ability to avoid longitudinal over-fitting and correct nonlinear catheter rotation during nonrigid rotational registration, highlight the potential wide-ranging applicability of our presented coregistration method.