Cardiac Computed Tomography Data Research Articles

Left ventricular longitudinal strain analysis using cardiac computed tomography for the diagnosis of cardiac amyloidosis

Abstract Introduction Cardiac amyloidosis (CA) results in a restrictive cardiomyopathy caused by extracellular deposition of proteins in the myocardium, demanding early identification for effective management. Left ventricular (LV) strain, mainly evaluated by echocardiography or cardiac magnetic resonance, provides sensitive and specific indicators for detecting CA, particularly apical sparing. It represents a pattern where the longitudinal strain (LS) in the basal and middle segments of LV is more impaired compared to the apical segments.¹ Cardiac computed tomography (CT) is useful not only for coronary artery evaluation but also for myocardial assessment, including LV ejection fraction (LVEF). Advanced software made it possible to analyse LS on cardiac CT (Figures A,B). Hypothesis: LS analysis using four-dimensional cardiac CT is helpful for the differential diagnosis of LV hypertrophied myocardial diseases and for detecting CA. Methods We analyzed 60 patients with LV hypertrophied myocardial diseases who underwent cardiac CT using 256-detector row or 320-detector row CT since 2009. Twenty patients of them were diagnosed with CA ( 70 ± 10 years, 14 males), the other 20 patients were diagnosed with hypertrophic cardiomyopathy (HCM) ( 60 ± 14 years, 12 males), and the rest of the 20 patients were diagnosed with severe aortic valve stenosis (AS) ( 86 ± 6 years, nine males). We analyzed LV global LS (GLS) and segmental LS using specific software and four-dimensional CT data. We evaluated relative apical LS as the value dividing the average LS of apical segments by the sum of the average LS of basal segments and mid-ventricular segments (Figure C). If the value was ≥ 1, apical sparing was defined as present. We compared the LS data and the percentage of apical sparing among those three myocardial diseases. Results There was no significant difference in LVEF among the three groups (52 ± 14%, 55 ± 27%, and 50 ± 18%, respectively; P = 0.15). There was no significant difference in GLS among the three groups (-10.6 ± 3.6%, -10.2 ± 5.2%, and -11.6 ± 3.8%, respectively; P = 0.87). Apical sparing was observed in 13 cases (65%) of CA, which was significantly higher than 3 cases (15%) of HCM or 4 cases(20%) of AS (P = 0.0002). Conclusions LV strain analysis using cardiac CT is helpful for detecting apical sparing. Advanced image analysis software has enabled LV strain analysis by cardiac CT, which is useful for the differential diagnosis of CA among LV hypertrophied diseases.Figure A,B,C

Bolus tracking from pulsed x-ray projections: A feasibility study using a five-dimensional cardiac CT contrast dynamics model.

Cardiac computed tomography (CT) exams are some of the most complex CT exams due to the need to carefully time the scan when the heart chambers are near the peak contrast concentration. With current "bolus tracking" and "timing bolus" techniques, after contrast medium is injected, a target vessel or chamber is scanned periodically, and images are reconstructed to monitor the opacification. Both techniques have opportunities for improvement, such as reducing the contrast medium volume, the exam time, the number of manual steps, and improving the robustness of correctly timing the peak opacification. The objective of our study is to (1) develop a novel autonomous cardiac CT clinical workflow to track contrast bolus dynamics directly from pulsed x-ray projections, (2) develop a new five-dimensional virtual cardiac CT data generation tool with programmable cardiac profiles and bolus dynamics, and (3) demonstrate the feasibility of projection-domain prospective bolus tracking using a neural network trained and tested with the virtual data to find the contrast peak. In our proposed workflow, pulsed mode projections (PMPs) are acquired with a wide-open collimator under sparse view conditions (monitoring phase). Each time a new PMP is acquired, the neural network is used to estimate the contrast enhancement inside the target chambers. To train such a network, we introduce a new approach to generate clinically realistic virtual scan data based on a five-dimensional cardiac model, by synthesizing user-defined contrast bolus dynamics and patient electrocardiogram profiles. In this study, we investigated a scenario with one single PMP per rotation. To find the optimal PMP view angle, 20 angles were explored. For each angle, 300 virtual exams were generated from 115 human subject datasets and divided into training, validation, and testing groups. Twenty neural networks were trained and evaluated in total to find the optimal network. Finally, a simple bolus peak time estimation algorithm was developed and evaluated by comparing to the ground truth bolus peak time. To evaluate the accuracy of a bolus time-intensity curve estimated by the network, the cosine similarity between the estimation and the ground truth was computed. The cosine similarity was larger than 0.97 for all projection angles. A view angle corresponding to the x-ray tube at 30 degrees from vertical (left-anterior of subject) showed the lowest errors. The amplitude of the estimated bolus curves (in Hounsfield Units) was not always correctly predicted, but the shape was accurately predicted. This resulted in an RMSE of 1.23s for the left chambers and 0.78s for the right chambers in the contrast peak time estimation. In this study, we proposed an innovative real-time way to predict the contrast bolus peak in cardiac CT as well as an innovative approach to train a neural network using virtual but clinically realistic data. Our trained network successfully estimated the shape of the time-intensity curve for the target chambers, which led to accurate bolus peak time estimation. This technique could be used for autonomous diagnostic cardiac CT to trigger a diagnostic scan for optimal contrast enhancement.

CAR and CSTR Cardiac Computed Tomography (CT) Practice Guidelines: Part 1 Coronary CT Angiography (CCTA).

Imaging the heart is one of the most technically challenging applications of Computed Tomography (CT) due to the presence of cardiac motion limiting optimal visualization of small structures such as the coronary arteries. Electrocardiographic gating during CT data acquisition facilitates motion free imaging of the coronary arteries. Since publishing the first version of the Canadian Association of Radiologists (CAR) cardiac CT guidelines, many technological advances in CT hardware and software have emerged necessitating an update. The goal of these cardiac CT practice guidelines is to present an overview of the current evidence supporting the use of cardiac CT in various clinical scenarios and to outline standards of practice for patient safety and quality of care when establishing a cardiac CT program in Canada.

Left atrial appendage filling defect in exclusive early-phase scanning of dual-phase cardiac computed tomography: An indicator for elevated thromboembolic risk.

Dual-phase cardiac computed tomography (CCT) has been applied to detect left atrial appendage (LAA) thrombosis, which is characterized as the presence of left atrial appendage filling defects (LAADF) in both early- and delayed-phase scanning. However, the clinical implication of LAAFD in exclusive early-phase scanning (LAAFD-EEpS) of CCT in patients with atrial fibrillation (AF) is unclear. The baseline clinical data and dual-phase CCT findings in 1183 AF patients (62.1 ± 11.6 years, 59.9% male) was collected and analyzed. A further analysis of CCT and transesophageal echocardiography (TEE) data (within 5 days) in a subgroup of 687 patients was performed. LAAFD-EEpS was defined as LAAFD present in early-phase and absent in delayed-phase scanning of dual-phase CCT. A total of 133 (11.2%) patients were detected with LAAFD-EEpS. Patients with LAAFD-EEpS had a higher prevalence of ischemic stroke or transient ischemic attack (TIA) (p < 0.001) and a higher predefined thromboembolic risk (p < 0.001). In multivariate analysis, a history of ischemic stroke or TIA was independently associated with LAAFD-EEpS (odds ratio [OR] 11.412, 95% confidence interval [CI] 6.561-19.851, p < 0.001). When spontaneous echo contrast in TEE was used as the reference standard, the sensitivity, specificity, positive predictive value, and negative predictive value of LAAFD-EEpS was 77.0% (95% CI 66.5-87.6%), 89.0% (95% CI 86.5-91.4%), 40.5% (95% CI 31.6-49.5%), 97.5% (96.3-98.8%), respectively. In AF patients, LAAFD-EEpS is not an uncommon finding in dual-phase CCT scanning, and is associated with elevated thromboembolic risk.

Abstract 16540: Left Ventricular Longitudinal Strain Analysis Using Four-Dimensional Computed Tomography for the Detection of Apical Sparing in Cardiac Amyloidosis

Introduction: Cardiac computed tomography (CT) not only allows for coronary artery evaluation but also enables myocardial assessment, including left ventricular (LV) ejection fraction (LVEF) and extracellular volume fraction. Advanced software makes it possible to analyze LV longitudinal strain (LS) on CT (Figures A and B). Hypothesis: LS analysis using four-dimensional cardiac CT is helpful for the differential diagnosis of LV hypertrophied myocardial diseases and detect cardiac amyloidosis (CA). Methods: We analyzed 45 patients with LV hypertrophied myocardial diseases who underwent cardiac CT using 256-detector row or 320-detector row CT in our institutions since 2009. Fifteen patients of them were diagnosed with CA (69 ± 9 years, 12 males), the other 15 patients were diagnosed with hypertrophic cardiomyopathy (HCM) (63 ± 16 years, nine males), and the rest of the 15 patients were diagnosed with aortic valve stenosis (AS) (83 ± 8 years, seven males). We analyzed LV global LS (GLS) and segmental LS using specific software and four-dimensional CT data. We evaluated relative apical LS as the value dividing the average LS of apical segments by the sum of the average LS of basal segments and mid-ventricular segments (Figure C). If the value was ≥ 1, apical sparing was defined as present. We compared the LS data and the percentage of apical sparing among those three myocardial diseases. Results: There was no significant difference in LVEF among the three groups (54 ± 12%, 58 ± 13%, and 50 ± 18%, respectively; P = 0.39). There was no significant difference in LV global LS among the three groups (-12.2 ± 3.2%, -11.2 ± 5.0%, and -11.0 ± 5.4%, respectively; P = 0.75). Apical sparing was observed in 6 cases (40%) of CA, which was significantly higher than in one case (7%) of HCM or AS (P = 0.02). Conclusions: Advanced image analysis software has made LVLS analysis by cardiac CT possible. It is considered helpful in detecting apical sparing, specifically in CA.

Evaluation of automatic pericardial segmentation methods in computed tomography images

Abstract Funding Acknowledgements Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Fundação para a Ciência e Tecnologia - FCT. Pericardial fat has been associated with the development of many cardiovascular diseases. Non-invasive pericardial fat assessment may be performed through cardiac computed tomography (CCT), with a first step being the segmentation of the pericardial layers, followed by the application of a threshold based on HU values. Given that manual pericardium segmentation is expensive, time-consuming and subject to inter-observer variability, automatic tools have been proposed. The purpose of this study is to compare automatic pericardial segmentation methods to manual segmentation by experts. Two automatic methods are compared: a commercial solution by Siemens and a deep learning based solution. A subset of 190 patients were randomly selected from the EPICHEART (The influence of EPICardial adipose tissue in HEART diseases) study (ClinicalTrials.gov: NCT03280433). All data was anonymized prior to analysis for the purposes of this study. All CCT scans were acquired on a Siemens Somatom Sensation 64 with a slice thickness of 3 mm. Manual pericardial segmentation was performed using 3D Slicer [1] by one of the authors (CS). Segmentation was repeated in a subset of 20 cases by CS and by a second observer (FN) to assess inter- and intra-observer variability. Automatic pericardial segmentation was performed using the Cardiac Risk Assessment tool provided within the Syngo.via software by Siemens Healthcare. A deep learning based segmentation tool was also developed. Publicly available CCT data with available pericardial segmentation was gathered: the CardiacFat dataset [2] which includes 20 patients acquired on two different scanners (Phillips and Siemens); and the OSIC-Konya dataset [3] which includes 87 pulmonary fibrosis patients. The data was used to train a U-Net architecture [4] for pericardial segmentation in 2D (512x512 pixels). The network was trained with a batch size of 2 and a learning rate of 0.0001 using the Dice loss. Excellent intra- and interobserver agreement was obtained with a Dice of 0.908 and 0.873 respectively and a mean absolute distance (MAD) between contours of 2.23 and 3.18mm respectively. The automatic Siemens and U-Net methods obtained however significantly lower performance with a Dice of 0.776 and 0.773 respectively and an MAD of 6.47 and 6.72mm respectively. In conclusion, both automatic solutions showed significantly lower performance in an external dataset when compared to manual pericardium segmentation, which could hinder their applicability in clinical studies to assess pericardial fat. Particularly for deep learning methods, generalization to external datasets is known to be challenging. The use of publicly available data and a vanilla architecture means that this approach can be replicated by any researcher, however, training with additional data and using more advanced architectures could yield improved results and enable the use of automatic deep learning methods in large clinical studies.

Computational fluid dynamics simulations of mitral paravalvular leaks in the human heart

Abstract Funding Acknowledgements Type of funding sources: Public Institution(s). Main funding source(s): Warsaw University of Technology - BIOTECHMED-3 project under the program Excellence Initiative: Research University. Background Presence of paravalvular leaks (PVL) can lead to hemolysis and high shear stress that affects erythrocytes passing through PVL channels may be the main reason behind this pathology. In vitro, shear stress forces above 300 Pa cause erythrocyte destruction. Distribution of shear stress can currently be precisely determined with computational fluid dynamics (CFD). CFD is a numerical modelling method based on solving equations of differential balance of mass, momentum and energy for a small section of fluid known as a computational cell. Purpose To investigate the magnitude of shear stress forces that affect erythrocytes in PVL channels and define properties of PVL channels that increase the likelihood of hemolysis. Methods Models of left-sided heart chambers with artificial mitral valves and PVLs were created based on cardiac computed tomography data from subjects with PVLs. Computational fluid dynamics principles were applied to create patterns of blood flow through PVL channels. 4 channels with cross-sectional areas (CSA) of 26.2 mm2 (model I), 15.7 mm2 (model 2), 20.4 mm2 (model 3) and 32 mm2 (model 4) were examined. Length of PVL channels was 6.5, 9.5, 7.3 and 3.25 mm respectively. In models I,III and IV the PVL channel was located anteriorly around the mitral annulus, whereas in model II a posterior location was described. Blood flow was simulated using a commercial CFD software (ANSYS Fluent 2020R1). Simulations were performed for heart rate of 60 beats per minute. The following variables were examined regarding blood flow through PVL channels: wall shear stress, shear stress in fluid, volume of PVL channels in which shear stress exceeded 300 Pa and duration of exposure of red blood cells to shear stress above 300 Pa. Obtained values were compared with lactate dehydrogenase (LDH) activities in subjects whose cardiac CTs were used to create PVL models. One of the models of the left ventricle is presented in picture 1. Studied PVL channels are presented in picture 2. Results In all models shear stress value of 300 Pa was exceeded. Maximal wall shear stress and maximal shear stress in fluid values were not related to CSA of the PVL channel. Lowest values of all examined variables were obtained for model 2, which had the longest PVL channel and a posterior location. The lowest LDH activity was noted in model with the lowest volume of the PVL channel with shear stress above 300 Pa (model 2) and the highest LDH activity in model with both the highest volume of the PVL channel with shear stress above 300 Pa and longest exposure to shear stress exceeding 300 Pa (model III). Conclusions Presence of PVLs is always accompanied by some degree of hemolysis. Shear stress values in PVL channels are not related to CSA of these channels. Volume of PVL channels in which shear stress exceeds 300 Pa and duration of exposure of erythrocytes to shear stress above 300 Pa may influence the severity of hemolysis.

PO-04-137 SCAR TRANSMURALITY IN VENTRICULAR ENDOCARDIAL UNIPOLAR ELECTROGRAMS IS RELATED TO POWER OF PATIENT-SPECIFIC FREQUENCY BANDS

Characteristic endocardial electrogram (EGM) features such as fractionation and late potentials have been associated with ventricular tachycardia (VT) substrate. Our prior analyses show that EGM frequency content allows for more accurate identification of mid-myocardial fibrosis within a given patient, compared to traditional bipolar or unipolar voltage thresholds. A relationship between frequency information and endocardial scar transmurality has not been described. To explore the relationship of frequency spectra to ventricular scar transmurality in patients undergoing VT catheter ablation. Thirteen patients with non-ischemic cardiomyopathy (NICM) undergoing VT ablation with pre-procedural tissue characterization using cardiac computed tomography (CCT) imaging with late-iodine enhancement were assessed. From the CCT data, scar transmurality was calculated for every EGM recording location. With multitaper spectral estimation, average normalized frequency content was calculated for regions with different levels of scar transmurality and compared to average frequency content from tissue locations with no scar. K-nearest neighbors classifiers were trained within patients to predict scar transmurality, assuming presence of scar is known. Frequency content of regions without scar is similar among patients. A comparison of the average normalized frequency spectra of the non-fibrotic endocardial tissue for each patient is presented. Differences in scar transmurality led to changes in strength of certain frequency bands, which varied between patients. Observed responses included a peak at 10-15 Hz whose magnitude increased with scar transmurality (panel B) and a peak at 35-40 Hz in regions with higher scar transmurality. Normalized frequency content predicted transmural scar above chance with at least p < .05 for all 13 patients. Frequency content of endocardial unipolar EGMs is related to scar transmurality in those regions. This relationship changes patient to patient, potentially due to differences in morphology of fibrotic tissue. Deviation from the consistent spectra seen in non-fibrotic tissue may be a strategy to identify fibrosis and these insights can inform development of physiological models of VT. Because of low EGM sample sizes in higher scar transmurality regions, more data should be collected to further support this claim.

Abstract 14337: Cardiac Computed Tomography for Preoperative Assessment of Valve Morphology in Aortic Valve Repair

Introduction: A pre-operative assessment of aortic valve anatomy is important in valve repair for aortic regurgitation (AR). Although echocardiogram provides precise information, clear visualization of entire aortic valve and accurate quantification of valve geometry are limited even with 3D transesophageal echocardiography. In this study, usefulness of cardiac computed tomography (CT) in the evaluation of aortic valve pathology was investigated. Methods: A total of 119 patients who underwent surgical treatment for severe AR from May 2016 to July 2021 and had preoperative CT were studied. From the CT data set, volume rendering movie image was reconstructed to visualize valve anatomy. Effective height (EH) and geometric height (GH) were measured by CT in diastole and compared to intraoperative measurements. Results: The quality of CT image was satisfactory in 100 patients (84%), acceptable in 17 patients (14%) and suboptimal in 2 patients (2%). CT could visualize such detailed anatomy as shown in the Figure. EH in 41 patients and GH in 67 were measured by both CT and surgery. The measurements showed a correlation in EH (r=0.79, p&lt;0.0001) and in GH (r=0.74, p&lt;0.0001) with minimal bias of -1.6 mm in EH and 0.4 mm in GH and narrow limits of agreement from -5.9 to2.6 mm in EH and from -3.7 to 4.6 mm in GH. Inter- observer variabilities in CT measurement of EH and GH were 3.8±2.9% and 2.6±1.8%, with interclass correlation coefficients of 0.997 and 0.980, respectively. Conclusions: Reproducibility of CT measurement was excellent, while there was a little discrepancy between CT and surgical measurement. Not all cases underwent intraoperative measurement, and cases with structurally complexity tended to have surgical measurement. Some errors may be included in also intraoperative measurements. CT feasibly visualized aortic valve en-face view with showing the etiology of AR, which gave useful information to surgeons who perform aortic valve repair.

Parameters of Flow through Paravalvular Leak Channels from Computational Fluid Dynamics Simulations—Data from Real-Life Cases and Comparison with a Simplified Model

Background: Shear forces affecting erythrocytes in PVL channels can be calculated with computational fluid dynamics (CFD). The presence of PVLs is always associated with some degree of hemolysis in a simplified model of the left ventricle (LV); however, data from real-life examples is lacking. Methods: Blood flow through PVL channels was assessed in two variants. Firstly, a PVL channel, extracted from cardiac computed tomography (CCT), was placed in a simplified model of the LV. Secondly, a real-life model of the LV was created based on CCT data from a subject with a PVL. The following variables were assessed: wall shear stress (τw) shear stress in fluid (τ), volume of PVL channel with wall shear stress above 300 Pa (V300), duration of exposure of erythrocytes to shear stress above 300 Pa (Vt300) and compared with lactate dehydrogenase (LDH) activity levels. Results: τw and τ were higher in the simplified model. V300 and Vt300 were almost identical in both models. Conclusions: Parameters that describe blood flow through PVL channels can be reliably assessed in a simplified model. LDH levels in subjects with PVLs may be related to V300 and Vt300. Length and location of PVL channels may contribute to a risk of hemolysis in mitral PVLs.

Comparison Between Echocardiography and Cardiac Computed Tomography in the Evaluation of Diastolic Dysfunction and Prediction of Heart Failure

Recent data indicate that left atrial (LA) function assessment by cardiac computed tomography (CT) is closely related to diastolic dysfunction (DD). Therefore, we aimed to perform a direct comparison between CT and echocardiography for diagnosis of advanced DD and prediction of future heart failure or cardiovascular death. We identified 340 patients who had both spiral cardiac CT and a proximate echocardiogram. LA total emptying fraction (LATEF), a measure of global LA function, was automatically calculated from CT data, as a surrogate for diastolic function and was compared with echocardiographic grades of diastolic function. The area under the receiver operating characteristic curve for LATEF to differentiate between advanced DD (grades 2 and 3) and all other grades was 0.84 (0.79 to 0.88). Over a median of 4 years, 69 events (admissions for heart failure and cardiovascular deaths) occurred. By multivariate Cox analysis, LATEF &lt;40% provided incremental prognostic information after adjustments for advanced DD by echocardiography (hazard ratio 2.15, 95% confidence interval 1.13 to 3.94). There was a significant interaction (p=0.03) between LATEF and echocardiography-based diastolic grades. Stratified analyses within the diastolic function groups revealed that LATEF &lt;40% was equivalent to echocardiography in predicting events in the subgroup with advanced DD by echocardiography (p=0.20) but was associated with a significantly higher event rates in patients with normal filling pressures (p=0.0001) or indeterminate diastolic function (p=0.04) by echocardiography. In conclusion, LA function derived from CT can accurately detect advanced DD diagnosed by echocardiography and has additive value to echocardiography-derived DD.

Computed tomography reference dimensions for identification of stented surgical mitral bioprostheses valve size

BackgroundSelection of the transcatheter heart valve size for a mitral valve-in-valve procedure is based on the type and manufacturer’s labelled size. However, accurate information of surgical heart valve (SHV) size may not be available in the patient’s medical record. The purpose of this study is to establish reference data for computed tomography (CT) dimensions of commonly used mitral SHV in order to determine the manufacturer’s labelled size from a cardiac CT data set. MethodsCT datasets of 105 patients with surgical mitral bioprosthesis and available manufacturer labeled datasets were included in the analysis. CT derived valve dimensions were assessed by two observers using multiplanar reformats aligned with the basal sewing ring. A circular region of interest was used in a standardized fashion to minimize influence of image acquisition and reconstruction parameters. Interobserver variability was assessed by Bland-Altman analysis. ResultsThe CT-derived dimensions were stratified by valve size and type, and SHV properties were demonstrated for 5 common valve types. Variability of measurements was small and inter-observer limits of agreement were narrow. Stratified by SHV type, no overlap was noted for CT-derived dimensions among different SHV sizes . A reference table of CT characteristics of surgical mitral bioprosthesis types was created. ConclusionThe study provides reference CT data for determining the manufacturers’ labeled SHV size across a range of commonly used mitral SHVs. The findings will be important to help identify types of surgical mitral bioprosthesis utilizing CT characteristics for patients without SHV size documentation.

Computed tomography-derived characterisation of pericoronary,epicardial and paracardial adipose tissue and its association with myocardial ischemia as assessed by computed and invasive fractional flow

Abstract Introduction Increased pericoronary adipose tissue (PCAT) computed tomography (CT) attenuation derived from coronary CT angiography (CTA) around the right coronary artery (RCA) reflects coronary inflammation and relates to cardiac mortality. Purpose We aimed to investigate the yet unclear association between CT-derived characterisation of different cardiac adipose tissue compartments and the presence of myocardial ischemia as assessed by fractional flow reserve (FFR). Methods 133 stable individuals (64 years, 74% male) with coronary artery disease (CAD) underwent CTA including computed FFR (FFR-CT) measurement followed by invasive angiography with FFR (invasive FFR) assessment. The CT attenuation (HU) and volume (mm3) of PCAT were quantified around the RCA (10 to 50 mm from RCA ostium), the proximal 40 mm of the left anterior descending artery (LAD) and the circumflex artery (LCX) with the help of semi-automated software. The per patient PCAT CT attenuation was calculated as followed: (PCAT CT attenuation of RCA+LAD+LCX)/3. Quantification of epicardial adipose tissue (EAT) and paracardial adipose tissue (PAT; all intrathoracic adipose tissue outside the pericardium) were performed in non-contrast cardiac CT data sets using a fully automated deep-learning based algorithm. Results Median FFR-CT was 0.86 [0.79, 0.91] and median invasive FFR was 0.87 [0.81, 0.93]. Patients with presence of myocardial ischemia (n=26) defined by a FFR-CT threshold of ≤0.75 showed a significant higher PCAT CT attenuation of RCA (−75.1 HU vs. −81.1 HU, p=0.011) and per patient (−74.5 HU vs. −77.7 HU, p=0.045) than individuals without myocardial ischemia (n=107). In multivariable analysis adjusted for age, BMI, gender and traditional risk factors, both RCA and per patient PCAT CT attenuation were significant predictors of myocardial ischemia as assessed by FFRCT ≤0.75. Between individuals with myocardial ischemia compared to individuals without myocardial ischemia there was no significant difference neither in the volume and CT attenuation of EAT and PAT nor in the PCAT volume of RCA, LAD, LCX and per patient PCAT volume. Conclusions Our observations suggest that PCAT CT attenuation instead of PCAT volume, EAT and PAT measures might be associated with the presence of myocardial ischemia as assessed by FFR. Funding Acknowledgement Type of funding sources: Foundation. Main funding source(s): German Heart Foundation e.V.

Live integration of comprehensive cardiac CT for myocardial fibrosis and coronary anatomy with electroanatomical mapping in patients with refractory ventricular tachycardia: a pilot study

Abstract Funding Acknowledgements Type of funding sources: None. Aim of the study was to verify the feasibility and accuracy of live integration of myocardial fibrosis evaluated at CCT with EAM. The present is the first report of live integration of cardiac computed tomography (CCT) data for myocardial fibrosis and coronary anatomy with electroanatomical mapping (EAM). We prospectively enrolled all patients admitted with a clinical indication to endocardial and epicardial EAM before radiofrequency catheter ablation (RFCA) of refractory ventricular tachycardia (VT) and an absolute contraindication to cardiac magnetic resonance. All patients underwent per protocol CCT for myocardial fibrosis and coronary anatomy evaluation, before RFCA procedures. Sensitivity, specificity, negative predictive value, positive predictive value and diagnostic accuracy were assessed for myocardial fibrosis evaluation with CCT vs EAM on a per segment-basis taking into consideration both any type of fibrosis and ischemic vs non ischemic subtypes. Live integration feasibility of CCT vs EAM was evaluated for every patients. Live integration feasibility and diagnostic performance of CCT vs EAM for myocardial fibrosis identification was evaluated for every patients. EAM adverse events were recorded as well. In all patients CCT data were successfully integrated with EAM during RFCA procedure. All patients had myocardial fibrosis correctly identified at CCT vs EAM on a per-patients basis. A diagnostic accuracy of 94.1% for detection of any type of myocardial fibrosis at CCT vs EAM was recorded. No pericardial tamponade and/or pericardial effusion were recorded. CCT identification of myocardial fibrosis is feasible and accurate vs EAM in a very selected high risk patients with clinical indication to RFCA of VT and contraindication to CMR. CCT images integration during EAM is feasible and enable to provide electrophysiologist useful information regarding myocardial fibrosis and coronary arteries location, possibly avoiding invasive coronary angiography.

Roles of Cardiac Computed Tomography in Guiding Transcatheter Tricuspid Valve Interventions.

The field of transcatheter tricuspid valve interventions (TTVI) is rapidly evolving to meet a well-defined but unmet clinical need. Severe tricuspid regurgitation is common and is associated with significant morbidity and mortality. Surgical options are limited and of high risk. The success of TTVI depends on careful procedural planning, and cardiac computed tomography (CCT) plays an emerging key role. TTVI technologies have various targets, including the leaflets, annulus, and venae cavae, along with valve replacement. Based on the planned procedure, CCT allows for device sizing, careful assessment of the access route, and comprehensive analysis of relevant adjacent anatomic structures to enhance procedural safety. It can also evaluate right-sided heart function, and its data can be for fusion imaging and 3D printing. Procedural planning is key to TTVI's success and is highly dependent on high-quality CCT data. This review details the comprehensive roles of CCT, specifics of the dedicated TTVI protocol, and its limitations.

Cardiac computed tomography for therapy targeting in surgical repair of anteroapical left ventricular aneurysms: assessment of aneurysm volume and of anticipated residual left ventricular volume

Abstract Funding Acknowledgements Type of funding sources: None. Background Surgical ventricular repair (SVR) is an established treatment option in patients with heart failure (HF) due to left ventricular (LV) aneurysms, whereby LV volume reduction is the principal therapeutic target. Precise planning therefore is essential for postoperative improvement of HF symptoms. Purpose In this study we evaluated the potential of cardiac computed tomography (CCT) to estimate the aneurysm volume and to predict the achievable residual LV volume. Methods 205 patients (11/2005-01/2016, m:w = 151:54, median 63.4 years; mean NYHA class 3.03) with anteroapical LV aneurysm underwent SVR combined with coronary artery bypass grafting (77%), mitral valve repair/replacement (19%), and LV thrombectomy (19%). CCT was performed before and 7 days after surgery. Volumetric assessment was made using dedicated software (syngo.via Cardiac Function, Siemens AG). Preoperative CCT data of 48 consecutive patients were analyzed and then matched with effectively achieved postoperative volumes. To separate the aneurysm volume in the systole and diastole a plane determined by three landmarks on borders of scared to intact LV myocardium (antero-septal, lateral and inferior) was used. In this way ensued the retrospective estimation of the aneurysm volume (AnV/AnVI) and anticipated LV end diastolic and end systolic volume (LVEDVI, LVESVI). Results Mean diastolic and systolic estimated AnV were 92 ± 56.6 ml and 83.5 ± 61.6 ml respectively. Relation of AnV to LVEDV and to LVESV was 29.2% and 38.2%, correspondingly. There was significant correlation between anticipated and effectively achieved LVEDV and LVESV (r = 0.87 and r = 0.88, respectively, p &amp;lt; 0.0001), and their indexed values (r = 0.83 and r = 0.83, respectively, p &amp;lt; 0.0001). Anticipated LVEDVI was only 10.3 ± 22.5 ml/m2 greater than achieved LVEDVI (p = 0.003), and anticipated LVESVI was only 2.4 ± 20.3 ml/m2 greater than achieved LVESVI (p = 0.433). Conclusions Estimation of aneurysm volume and anticipated postoperative LV volume allows to predict if the therapeutic targets can be successfully achieved in individual patients. Based on the CCT assessment we propose an approach for surgical planning in anterior LV aneurysms.

Multi-institution assessment of the use and risk of cardiovascular computed tomography in pediatric patients with congenital heart disease

BackgroundCardiac computed tomography (CT) is increasingly used in pediatric patients with congenital heart disease (CHD). Variability of practice and of comprehensive diagnostic risk across institutions is not known. MethodsFour centers prospectively enrolled consecutive pediatric CHD patients <18 years of age undergoing cardiac CT from January 6, 2017 to 1/30/2020. Patient characteristics, cardiac CT data and comprehensive diagnostic risk were compared by age and institutions. Risk categories included sedation and anesthesia use, vascular access, contrast exposure, cardiovascular medication, adverse events (AEs), and estimated radiation dose. ResultsCardiac CT was performed in 1045 pediatric patients at a median (interquartile range, IQR) age of 1.7 years (0.3, 11.0). The most common indications were arterial abnormalities, suspected coronary artery anomalies, functionally single ventricle heart disease, and tetralogy of Fallot/pulmonary atresia. Sedation was used in 8% and anesthesia in 11% of patients. Peripheral vascular access was utilized for 93%. Median contrast volume was 2 ​ml/kg. Beta blockers were administered in 11% of cases and nitroglycerin in 2% of cases. The median (IQR) total procedural dose length product (DLP) was 20 ​mGy∗cm (10, 50). Sedation, vascular access, contrast exposure, use of cardiovascular medications and radiation dose estimates varied significantly by institution and age (p ​< ​0.001). Seven minor adverse events (0.7%) and no major adverse events were reported. ConclusionCardiac CT for CHD is safe in pediatric patients when appropriate CT technology and expertise are available. Scans can be acquired at relatively low radiation exposure with few minor adverse events.

Improved Visualisation of Patient-Specific Heart Structure Using Three-Dimensional Printing Coupled with Image-Processing Techniques Inspired by Astrophysical Methods

The aim of this study is to use image-processing techniques developed in the field of astrophysics as inspiration for a novel approach to the three-dimensional (3D) imaging of periprocedural medical data, with the intention of providing improved visualisation of patient-specific heart structure and thereby allowing for an improved quality of procedural planning with regards to individualized cardiovascular healthcare. Using anonymized patient DICOM data for a cardiac computed tomography (CT) angiography, two-dimensional slices of the patient's heart were processed using a series of software packages in order to produce an accurate 3D representation of the patient's heart tissue as a computer-generated stereolithography (STL) file, followed by the creation of a tactile 3D printout. We find that the models produced provide clear definition of heart structure, in particular in the left atrium, left ventricle and aorta. This level of clarity also allows for the aortic valve to be observed and 3D printed. This study provides a step-by-step blueprint of how this can be achieved using open source software, specifically Slicer 4.8.1, MeshLab and AutoDesk Netfabb. In addition, the implementation of astrophysical image-processing techniques shows an improvement in modelling of the heart based on the CT data, in particular in the case of small-scale features where echocardiography has previously been required for more reliable results.

Left Atrium Wall-mapping Application for Wall Thickness Visualisation

The measurement method for the LA wall thickness (WT) using cardiac computed tomography (CT) is observer dependent and cannot provide a rapid and comprehensive visualisation of the global LA WT. We aim to develop a LA wall-mapping application to display the global LA WT on a coplanar plane. The accuracy, intra-observer, and inter-observer reproducibility of the application were validated using digital/physical phantoms, and CT images of eight patients. This application on CT-based LA WT measures were further validated by testing six pig cardiac specimens. To evaluate its accuracy, the expanded maps of the physical phantom and pig LA were generated from the CT images and compared with the expanded map of the digital phantom and LA wall of pig heart. No significant differences (p > 0.05) were found between physical phantom and digital phantom as well as pig heart specimen and CT images using our application. Moreover, the analysis was based on the LA physical phantom or images of clinical patients; the results consistently demonstrated high intra-observer reproducibility (ICC > 0.9) and inter-observer reproducibility (ICC > 0.8) and showed good correlation between measures of pig heart specimen and CT data (r = 0.96, p < 0.001). The application can process and analyse the LA architecture for further visualisation and quantification.

3D Modelling and Printing Technology to Produce Patient-Specific 3D Models

A comprehensive knowledge of mitral valve (MV) anatomy is crucial in the assessment of MV disease. While the use of three-dimensional (3D) modelling and printing in MV assessment has undergone early clinical evaluation, the precision and usefulness of this technology requires further investigation. This study aimed to assess and validate 3D modelling and printing technology to produce patient-specific 3D MV models. A prototype method for MV 3D modelling and printing was developed from computed tomography (CT) scans of a plastinated human heart. Mitral valve models were printed using four 3D printing methods and validated to assess precision. Cardiac CT and 3D echocardiography imaging data of four MV disease patients was used to produce patient-specific 3D printed models, and 40 cardiac health professionals (CHPs) were surveyed on the perceived value and potential uses of 3D models in a clinical setting. The prototype method demonstrated submillimetre precision for all four 3D printing methods used, and statistical analysis showed a significant difference (p<0.05) in precision between these methods. Patient-specific 3D printed models, particularly using multiple print materials, were considered useful by CHPs for preoperative planning, as well as other applications such as teaching and training. This study suggests that, with further advances in 3D modelling and printing technology, patient-specific 3D MV models could serve as a useful clinical tool. The findings also highlight the potential of this technology to be applied in a variety of medical areas within both clinical and educational settings.