ECG-gated CTA Research Articles

Normative computed tomography angiography values of the aortic root, aorta, and aortic arch in children.

Our study reports systolic and diastolic ECG-gated CTA Z-scores along with normative curves in relation to BSA for the aortic root, aorta, and aortic arch in children. • Normative data for intracardiac and extracardiac vascular structures in the pediatric population are available for echocardiography, cardiac MRI and non-ECG gated CTA. • Z-scores with standard deviations are commonly used in children, but SDs are not constant across body sizes due to heteroscedasticity. • Allometric exponent was derived for each parameter and the parameter/body surface area (BSA) was established. • This is the first ECG-gated CTA study to provide normative en face systolic, diastolic diameters and cross-sectional areas along with Z-scores and normative curves for the aortic root, aorta and aortic arch in children.

Dynamic Computed Tomography Angiography for capturing vessel wall motion: A phantom study for optimal image reconstruction.

Reliably capturing sub-millimeter vessel wall motion over time, using dynamic Computed Tomography Angiography (4D CTA), might provide insight in biomechanical properties of these vessels. This may improve diagnosis, prognosis, and treatment decision making in vascular pathologies. The aim of this study is to determine the most suitable image reconstruction method for 4D CTA to accurately assess harmonic diameter changes of vessels. An elastic tube (inner diameter 6 mm, wall thickness 2 mm) was exposed to sinusoidal pressure waves with a frequency of 70 beats-per-minute. Five flow amplitudes were set, resulting in increasing sinusoidal diameter changes of the elastic tube, measured during three simulated pulsation cycles, using ECG-gated 4D CTA on a 320-detector row CT system. Tomographic images were reconstructed using one of the following three reconstruction methods: hybrid iterative (Hybrid-IR), model-based iterative (MBIR) and deep-learning based (DLR) reconstruction. The three reconstruction methods where based on 180 degrees (half reconstruction mode) and 360 degrees (full reconstruction mode) raw data. The diameter change, captured by 4D CTA, was computed based on image registration. As a reference metric for diameter change measurement, a 9 MHz linear ultrasound transducer was used. The sum of relative absolute differences (SRAD) between the ultrasound and 4D CTA measurements was calculated for each reconstruction method. The standard deviation was computed across the three pulsation cycles. MBIR and DLR resulted in a decreased SRAD and standard deviation compared to Hybrid-IR. Full reconstruction mode resulted in a decreased SRAD and standard deviations, compared to half reconstruction mode. 4D CTA can capture a diameter change pattern comparable to the pattern captured by US. DLR and MBIR algorithms show more accurate results than Hybrid-IR. Reconstruction with DLR is >3 times faster, compared to reconstruction with MBIR. Full reconstruction mode is more accurate than half reconstruction mode.

Investigation of factors determining haemodynamic relevance of leaflet thrombosis after transcatheter aortic valve implantation.

To determine the conditions under which early hypoattenuated leaflet thickening (HALT) after transcatheter aortic valve implantation (TAVI) becomes haemodynamically relevant. The study included 100 patients (age: 81.5 ± 5.5 years; female 63%), thereof 50 patients with HALT. After anonymization and randomization, blinded readers measured maximum thrombus thickness per prosthesis (MT_pr) and movement restriction (MR_pr) on electrocardiogram (ECG)-gated whole heart cycle computed tomography angiography. These measurements were compared with echocardiographic mean pressure gradient (mPG), its increase from baseline (ΔmPG), and Doppler velocity index (DVI). Haemodynamic valve deterioration (HVD) was defined as mPG > 20 mmHg. Age, body mass index, valve type, valve size, left ventricular ejection fraction, and atrial fibrillation were considered as influencing factors. Multiple regression analysis revealed that only valve size (P = 0.001) and MT_pr (P = 0.02) had a significant influence on mPG. In an interaction model, valve size moderated the effect of MT_pr on mPG significantly (P = 0.004). Sub-group analysis stratified by valve sizes showed a strong correlation between MT_pr and echocardiographic parameters for 23 mm valves (mPG: r = 0.57, ΔmPG: r = 0.68, DVI: r = 0.55, each with P < 0.001), but neither for 26 nor 29 mm valves (r < 0.2, P > 0.2 for all correlations). Six of seven prostheses with HVD had a 23 mm valve diameter, while one had 29 mm (P = 0.02). Early HALT rarely causes significant mPG increase. Our study shows that valve size is a key factor influencing the haemodynamic impact of HALT. In small valve sizes, mPG is more likely to increase. Our study is the first to offer in vivo evidence supporting previous in vitro findings on this topic.

Reduced Pulmonary Artery Distensibility Predicts Persistent Pulmonary Hypertension and 2-Year Mortality in Patients with Severe Aortic Stenosis Undergoing TAVR

Post-TAVR persistent pulmonary hypertension (PH) is a better predictor of poor outcome than pre-TAVR PH. In this longitudinal study we sought to evaluate whether pulmonary artery (distensibility (DPA) measured on preprocedural ECG-gated CTA is associated with persistent-PH and 2-year mortality after TAVR. Three hundred and thirty-six patients undergoing TAVR between July 2012 and March 2016 were retrospectively included and followed for all-cause mortality until November 2017. All patients underwent retrospectively ECG-gated CTA prior to TAVR. Main pulmonary artery (MPA) area was measured in systole and in diastole. DPA was calculated as: [(area-MPAmax-area-MPAmin)/area-MPAmax]%. ROC analysis was performed to assess the AUC for persistent-PH. Youden Index was used to determine the optimal threshold of DPA for persistent-PH. Two groups were compared based on a DPA threshold of 8% (specificity of 70% for persistent-PH). Kaplan-Meier, Cox proportional-hazard, and logistic regression analyses were performed. The primary clinical endpoint was defined as persistent-PH post-TAVR. The secondary endpoint was defined as all-cause mortality 2 years after TAVR. Median follow-up time was 413 (interquartiles 339-757) days. A total of 183 (54%) had persistent-PH and 68 (20%) patients died within 2-years after TAVR. Patients with DPA<8% had significantly more persistent-PH (67% vs 47%, p<0.001) and 2-year deaths (28% vs 15%, p=0.006), compared to patients with DPA>8%. Adjusted multivariable regression analyses showed that DPA<8% was independently associated with persistent-PH (OR 2.10 [95%-CI 1.3-4.5], p=0.007) and 2-year mortality (HR 2.91 [95%-CI 1.5-5.8], p=0.002). Kaplan-Meier analysis showed that 2-year mortality of patients with DPA<8% was significantly higher compared to patients with DPA≥8% (mortality 28% vs 15%; log-rank p=0.003). DPA on preprocedural CTA is independently associated with persistent-PH and two-year mortality in patients who undergo TAVR.

483 High-pitch Non-ecg-gated Ct Angiography Fortranscatheter Aortic Valvereplacement Planning: A Comparison To A Ecg-gated Cta Protocol And Impact On Clinical Outcome

Introduction: ECG-gated vs high-pitch non-ECG-gated CT angiography (CTA) for trans-catheter aortic valve replacement (TAVR) planning has been controversially discussed, with current recommendations of ECG-gated CTA. However, the impact on clinical outcome, including post-interventional paravalvular leakage (PVL), remains unclear. Thus, the purpose of this study was to compare a retrospectively ECG-gated CTA against a high-pitch non-ECG-gated CTA protocol for TAVR planning and their associated impact on clinical outcome.

Evaluation of electrocardiogram-gated computed tomography angiography to quantify changes in geometry and dynamic behavior of the iliac artery after placement of the Gore Excluder Iliac Branch Endoprosthesis.

The GORE® EXCLUDER® Iliac Branch Endoprosthesis (IBE) is designed to treat iliac aneurysms with preservation of blood flow through the internal iliac artery (IIA). Little is known about the influence of IBE placement on the IIA geometry. This study aimed to provide detailed insights in the dynamic behavior and geometry of the common iliac artery (CIA) and IIA trajectory and how these are influenced after treatment with an IBE. Pre- and postoperative electrocardiogram-gated computed tomography angiography (ECG-gated CTA) scans were acquired in a prospective study design and analyzed with in-house written algorithms designed for aorto-iliac and endoprosthesis deformation evaluation. Cardiac pulsatility-induced motion patterns and pathlengths were computed by tracking predefined locations on the aorto-iliac tract. Centerlines through the CIA-IIA trajectory were used to investigate the static and dynamic geometry, including curvature, torsion, length and Tortuosity Index (TI). Fourteen CIA-IIA trajectories were analyzed before and after IBE placement. Cardiac pulsatility-induced motion and pathlengths increased after IBE placement, especially at mid IIA and the first IIA bifurcation (P≤0.04). After IBE placement, static and dynamic curvature, length and TI decreased significantly (P<0.05). Furthermore, the average dynamic torsion increased significantly (P=0.030). The remaining geometrical outcomes were not statistically significant. The placement of an IBE device stiffens and straightens the CIA-IIA trajectory. Its relation with clinical outcome is yet to be investigated, which can be done thoroughly with the ECG-gated CTA algorithms used in this study.

Abstract 10288: Reduced Pulmonary Artery Distensibility: A Predictor of Persistent Pulmonary Hypertension and 2-Year Mortality Post-Transcatheter Aortic Valve Replacement in High-Risk Patients with Severe Aortic Stenosis

Introduction: Persistent pulmonary hypertension (PH) post-TAVR is a better predictor of poor outcome than pre-TAVR PH, possibly due to longstanding vascular damage involving loss of pulmonary artery (PA) elasticity. In this study we sought to evaluate whether PA distensibility (D PA ) measured on pre-procedural ECG-gated CTA is associated with persistent-PH and 2-year mortality after TAVR. Hypothesis: Reduced D PA is a predictor of persistent-PH and mortality post-TAVR. Methods: 336 patients undergoing TAVR between July 2012 and March 2016 were retrospectively included. All patients underwent retrospectively ECG-gated CTA of the chest, with reconstruction of 10 phases over the cardiac cycle (0%- 90% of the R-R interval) prior to TAVR. Patients were followed for all-cause mortality. Main pulmonary artery (MPA) area was measured at 20% (area-MPA 20 ) and 80% (area-MPA 80 ) of the R-R interval. D PA was calculated as follows: [(area-MPA 20 -area-MPA 80 )/area-MPA 20 ]%. Persistent-PH was defined as pre-TAVR RVSP&gt;35mmHg which persisted &gt;35mmHg in post-TAVR echocardiography. 2 groups were compared based on D PA &lt;8% (specificity of 70% for persistent-PH). Kaplan-Meier, Cox proportional-hazard and logistic regression analyses were performed. Results: Median follow-up time was 413 (interquartiles 339-757) days. A total of 68 (20%) patients died within 2 years after TAVR and 183 (54%) had persistent-PH. Those with D PA &lt;8% had significantly more atrial fibrillation (50% vs 35%, p&lt;0.001), 2-year deaths (28% vs 15%, p=0.006) and persistent-PH (67% vs 47%, p&lt;0.001), compared to those with D PA &gt;8%. Multivariable regression analyses adjusted for age, sex, STS-score, cardiac risk, frailty≥2 and NYHA≥III, showed that D PA &lt;8% was independently associated with two-year mortality (HR 2.91 [95%-CI 1.5-5.8], p=0.002) and persistent-PH (OR 2.10 [95%-CI 1.3-4.5], p=0.007). Kaplan-Meier analysis showed that mortality of patients with D PA &lt;8% was significantly higher compared to patients with D PA ≥8% (mortality 28% vs 15%; log-rank p=0.003). Conclusion: D PA on pre-procedural CTA is independently associated with persistent-PH and two-year mortality in patients who undergo TAVR and could be a valuable parameter for risk stratification of TAVR candidates.

THREE-DIMENSIONAL PRINTING OF CUSTOM SEMIFLEXIBLE AORTIC ROOT MODELS FOR OPERATIVE PLANNING AND SURGICAL PROCTORING OF PERCEVAL VALVE IMPLANTATION

<h3>BACKGROUND</h3> The Perceval Valve (LivaNova, London, United Kingdom) is a rapid-deployment aortic bioprosthesis with a stentless self-expanding design conducive to minimally-invasive approaches. Uptake of this valve may be limited by sizing-related nuances and its unique implantation technique. Three-dimensional modeling and printing of custom patient-specific models can be used for surgical teaching and preoperative planning. Herein, we describe our method for 3D-printing aortic roots using a semi-flexible material and demonstrate their utility for sizing and surgical planning before Perceval Valve Implantation. <h3>METHODS AND RESULTS</h3> Semiflexible models of aortic roots were virtually modelled and 3D-printed from DICOM files containing contrast-enhanced ECG-gated CTA images of the thoracic aorta obtained in patients awaiting surgical aortic valve replacement via right anterior minithoracotomy. Segmentation of the aortic root, annulus and the left ventricular outflow tract was performed using a free, open source, multi-platform software package (http://slicer.org). In Slicer, a three-dimensional shell was generated around the luminogram model and then hollowed out, replicating the interior of the aortic root. After converting the aortic surfaces to standard tessellation language (STL), the models were printed using Thermoplastic Polyurethane (NinjaFlex, NinjaTek, PA,USA) in a direct drive extruder desktop 3D printer (Printrbot Simple Metal, Printrbot, USA). Preliminary model validation was performed in a prospective and blinded manner. Surgeons sized two de-identified aortic roots prior to the patient's operation. Implantation was then performed in the operating room without knowledge of the model sizing. The same size selected in the model corresponded to the size implanted in the operating room. The root models correctly predicted the size of the implanted valve. They also demonstrated the consequences of incorrect sizing (Image). Undersizing resulted in poor leaflet coaptation. Oversizing resulted in pinwheeling or buckling of the Perceval valve, both oversizing-related complications. A prototype holder was developed for simulation of the implantation procedure, including guiding suture placement, traction-countertraction of the sutures and balloon expansion. <h3>CONCLUSION</h3> Custom 3D-printed semiflexible aortic roots allowed for simulation of intraoperative sizing and can reproduce surgically relevant signs of inappropriate sizing, including oversizing (pinwheeling and buckling) and undersizing (suboptimal coaptation). This model will be of use for preoperative planning, sizing and surgical proctoring for the Perceval valve. Custom modeling may accelerate the learning curve associated with this valve and improve uptake for use in minimally invasive aortic valve surgery, combined cases, and patients with small roots.

Utility of ECG-Gated CTA for Detecting and Classifying Coronary Artery Involvement in Patients With Type A Aortic Dissection and Sinus of Valsalva Involvement.

BACKGROUND. Extension of type A aortic dissection (TAAD) from the sinus of Valsalva (SV) into the coronary arteries is associated with a poor prognosis and requires direct coronary repair or coronary artery bypass grafting (CABG) depending on the extent of involvement. OBJECTIVE. The purpose of this study was to assess the diagnostic performance of ECG-gated aortic CTA with surgical findings as the reference for detection and classification of coronary artery involvement in patients with TAAD involving the SV. METHODS. This retrospective study included 112 patients who underwent preoperative ECG-gated aortic CTA that showed TAAD with SV involvement. Two radiologists independently reviewed CTA images for right coronary artery (RCA) and left coronary artery (LCA) involvement. Involvement was classified according to a previously described system as type A (coronary ostial dissection), B (dissection with coronary false channel), or C (complete detachment from aortic root with dissection encircling the coronary artery). The diagnostic performance of CTA was calculated with surgical findings as the reference; interreader agreement was assessed; and surgical interventions were summarized. RESULTS. At surgery, the RCA was uninvolved in 33 patients and had type A involvement in 45, type B involvement in 19, and type C involvement in 15 patients. The LCA was uninvolved in 70 patients and had type A involvement in 34 patients, type B involvement in eight patients, and type C involvement in no patient. For the two readers, sensitivity in making the diagnosis in the RCA was 86.7% and 91.1% for type A, 79.0% and 89.5% for type B, 86.7% and 93.3% for type C, and 97.5% and 98.7% for any involvement. Sensitivity for the LCA was 85.3% and 91.2% for type A, 87.5% and 100% for type B, and 100% for any involvement. Specificity for the RCA was 94.0% and 97.0% for type A, 95.7% and 96.7% for type B, 96.9% and 96.9% for type C, and 93.9% and 97.0% for any involvement. Specificity for the LCA was 96.2% and 98.7% for type A, 96.2% and 97.1% for type B, and 97.1% and 98.6% for any involvement. Interreader agreement for types of involvement ranged from a kappa value of 0.85 to 0.96. The most common interventions were aortic repair for SV involvement alone (55.7-63.6%), coronary artery repair for types A and B involvement (53.3-87.5%), and CABG for type C involvement (86.7%). CONCLUSION. ECG-gated CTA has high diagnostic performance in the detection and classification of coronary involvement in TAAD with SV involvement. CLINICAL IMPACT. CTA findings may help guide presurgical planning for patients with TAAD.

Estimation of Radiation Doses and Lifetime Attributable Risk of Radiation-induced Cancer from A Single Coronary Artery Bypass Graft Computed Tomography Angiography

Introduction: Despite worldwide consensus that coronary artery bypass graft computed tomography angiography (CABG CTA) confers benefit to patients when used for appropriate indications, the increased cancer risk due to radiation dose remains a concern. The aim of this study is the estimation of organ effective dose (ED) and lifetime attributable risk (LAR) of cancer incidence and mortality related to a single CABG CTA procedure. Methods and materials: This retrospective cross-sectional designed study included 102 CABG patients who, from January 2021 to June 2021, underwent a retrospective 64-slice ECG-gated CABG CTA covering the area of the grafts with optimal image quality. The estimation of ED was done using the imPACT CT Dosimetry spreadsheet. LAR of cancer incidence was estimated for CABG CTA using the website X-rayrisk.com. Results: The mean total ED of CABG procedure was 15.35 mSv. The highest organ doses were those to the lungs (5.04 mSv) and breast (4.49 mSv). The cancer risk is higher in female (1 in 1516) than in male patients (1 in 1762). The LAR of cancer is higher for the younger age group in both males and females. The total whole-body ED demonstrated that CABG CTA is equivalent to 154 chest radiographs or 37 screening mammography studies, which in turn correspond to approximately 4.3 or 5-years of natural background radiation, respectively. Conclusions: Despite many benefits of CABG CTA, it is associated with a non-negligible risk of malignancy, so a careful risk/benefit assessment is recommended in justifying CABG CTA procedures, especially for young female patients.

Reduced Pulmonary Artery Distensibility Is Independently Associated With 2-year Mortality In Transcatheter Aortic Valve Replacement Patients: A Retrospective Longitudinal Study

Introduction: Recent studies have shown that pulmonary artery (PA) distensibility on pre-TAVR ECG-gated CTA scans can detect PH due to left heart disease. In this longitudinal study we sought to evaluate whether PA distensibility measured on pre-procedural CTA is associated with 2-year mortality after TAVR.

Bicuspid aortic valve annulus: assessment of geometry and size changes during the cardiac cycle as measured with a standardized method to define the annular plane

PurposeBicuspid aortic valve (BAV) is a complex malformation affecting not merely the aortic valve. However, little is known regarding the dynamic physiology of the aortic annulus in these patients and whether it is similar to tricuspid aortic valves (TAV). Determining the BAV annular plane is more challenging than for TAV. Our aim was to present a standardized methodology to determine BAV annulus and investigate its changes in shape and dimensions during the cardiac cycle.MethodsBAV patients were prospectively included and underwent an ECG-gated cardiac CTA. The annulus plane was manually identified on reconstructions at 5% intervals of the cardiac cycle with a new standardized method for different BAV types. Based on semi-automatically defined contours, maximum and minimum diameter, area, area-derived diameter, perimeter, asymmetry ratio (AR), and relative area were calculated. Differences of dynamic annular parameters were assessed also per BAV type.ResultsOf the 55 patients included (38.4 ± 13.3 years; 58% males), 38 had BAV Sievers type 1, 10 type 0, and 7 type 2. The minimum diameter, perimeter, area, and area-derived diameter were significantly higher in systole than in diastole with a relative change of 13.7%, 4.8%, 13.7%, and 7.2% respectively (all p < 0.001). The AR was ≥ 1.1 in all phases, indicating an elliptic shape, with more pronounced flattening in diastole (p < 0.001). Different BAV types showed comparable dynamic changes.ConclusionsBAV annulus undergo significant changes in shape during the cardiac cycle with a wider area in systole and a more elliptic conformation in diastole regardless of valve type.Key Points• A refined method for the identification of the annulus plane on CT scans of patients with bicuspid aortic valves, tailored for the specific anatomy of each valve type, is proposed.• The annulus of patients with bicuspid aortic valves undergoes significant changes during the cardiac cycle with a wider area and more circular shape in systole regardless of valve type.• As compared to previously published data, the bicuspid aortic valve annulus has physiological dynamics similar to that encountered in tricuspid valves but with overall larger dimensions.

Impact of Cardiac Computed Tomographic Angiography on Diagnostic and Therapeutic Decisions in Patients with Suspected Prosthetic Heart Valve Dysfunction.

IntroductionComputed Tomography (CT) scan is a helpful tool to assess the coronary arteries and the great vessels. However, its routine use in the assessment of patients with suspected prosthetic valve dysfunction (PVD) has not been studied thoroughly.ObjectiveTo determine the impact of routine cardiac computed tomography angiography (CCTA) on diagnostic and therapeutic decisions in patients with suspected PVD.Methods and resultsThis was a prospective cohort study that was conducted on 50 consecutive patients with suspected PVD who underwent both 64-slice ECG-gated CT and transesophageal echocardiography (TEE). The gold standard was the intraoperative findings. Surgery was performed in forty-six patients. ECG-gated CT showed findings that were not detected by TEE in sixteen patients (32%) namely aortic root abscess, aortic pseudoaneurysm, paravalvular leakage (PVL), sclero-calcific disruption of sutures as cause of PVL, mechanical prosthesis occluder malfunction, an underlying thrombus as cause of malfunction and finally presence of aortic dissection. Furthermore, CTA findings dictated treatment changes in fourteen patients (28%).ConclusionThis study demonstrates that ECG-gated CTA has a complementary role to TEE in patients with suspected PVD. CCTA is more accurate in diagnosis of periannular complications (Aortic root abscess and Pseudo-aneurysm) and in delineating their anatomical relation to surrounding cardiac structures. Therefore CCTA can have important role in deciding and planning the method of correction whether surgical or percutaneous and has to be considered after TEE in patients with a high suspicion on PVD.

Assessment of aortic annulus dimensions for transcatheter aortic valve replacement (TAVR) with high-pitch dual-source CT: Comparison of systolic high-pitch vs. multiphasic data acquisition

ObjectivesTo evaluate a systolic ECG-gated high-pitch aortoiliac computed tomography (CT) angiography for planning transcatheter aortic valve implantation (TAVI). MethodsPatients referred for TAVI underwent a combined CT imaging with retrospective, multiphasic ECG-gating of the heart and systolic ECG-gated high-pitch aortoiliac CT angiography. Consecutive patients were retrospectively included in this study group. Heart rate (HR) and heart rate variability (HRV) were assessed during the high-pitch ECG prediction phase. Aortic annulus area (AAA) was planimetrically quantified on both datasets. While only one moment of cardiac cycle was available for measurements in the high-pitch CT, the point of time in the multiphasic CT was chosen, where AAA yielded maximum size. Hypothetical prosthesis sizing was compared between multiphasic vs. high-pitch CT. ResultsAmong 61 patients (44.2 % men, mean age: 83.3 ± 5.5 years) average heart rate and HRV were 71.0 ± 13.4 bpm and 7.3 ± 8.5 bpm. 20 patients (32.7 %) had atrial fibrillation at the time of image acquisition. There was a strong correlation of AAA as derived from multiphasic vs. the high-pitch CT (r = 0.98). The difference in AAA was 10.5 ± 17.1mm2 (455.1 ± 83.0 mm2 for multiphasic vs. 444.5 ± 87.2 mm2 for high-pitch CT) and did not reach statistical significance (p = 0.08). Hypothetical prosthesis sizing showed an agreement in 55 of 61 patients (90.2 %). A sizing based on the high-pitch CT resulted in smaller prosthesis choice in 6 patients, all of them suffering from atrial fibrillation. Mean effective radiation dose was 10.9 ± 6.1 mSv for cardiac CTA and 4.1 ± 1.0 mSv for high-pitch CTA. ConclusionFor patients with sinus rhythm, systolic high-pitch aortoiliac CTA provides adequate prosthesis size selection as compared with multiphasic ECG-gated cardiac CTA and may result in significantly reduced radiation exposition.

Evaluation of ECG-gated and Fast Low-Angle Shot (FLASH) Dual Source Computed Tomography Scanning Protocols for Transcatheter Aortic Valve Replacement

Transcatheter aortic valve replacement (TAVR) procedural success relies heavily on volumetric reconstruction imaging, particularly ECG-gated multi-detector row computed tomography. We postulated that single examination using fast low-angle shot (FLASH) dual source CT scanning (DS-CTA) could provide lower dose than ECG-gated CTA while maintaining the image quality. In this single-centre cohort study, all patients who underwent ECG-gated and FLASH DS-CTA were evaluated. Volumetric reconstructions were performed for both ECG-gated and FLASH DS-CTA to obtain nonsagittal views of the structures. ECG-gated cardiac CT was obtained to evaluate the aortic annular size while FLASH DS-CTA was obtained to examine the aortic and iliac vasculature as part of TAVR imaging protocol. We evaluated measures of aortic annulus, coronaries and sinus of Valsalva using ECG-gated and FLASH DS-CTA scanning protocols. Image quality assessments were performed using aortic root region-of-interest signal-to-noise ratio. A total of 130 patients (mean age 81.5 ± 9.2 years, 46.2% female, and 99.2% white) underwent both ECG-gated CT and FLASH DS-CTA. There were excellent correlations between aortic annular area (R2 = 0.934) and aortic annular perimeter (R2 = 0.923) measured by the two protocols. Only 2 (1.5%) patients had >10% difference between aortic annular measurements by ECG-gated and FLASH DS-CTA, while none of the patients had a >10% difference between aortic annular perimeter measured by ECG-gated and FLASH DS-CT scans. There was no significant difference in signal-to-noise ratio between the two methods (mean difference 13.4; 95% CI -2.1-28.8, p = 0.09). There was significantly lower radiation dose for FLASH DS-CTA than ECG-gated CT scan (mean dose-length product difference 404.38; 95% CI 328.9-479.87, p <0.001). The measurements by the two scans led to the same transcatheter valve size selection in majority of the 128 (98.5%) patients by balloon expandable valve sizing recommendations and 130 (100%) of patients by self-expanding valve sizing recommendations. Overall, FLASH DS-CTA and ECG-gated CT scans provided comparable image quality and aortic annular dimensions for pre-TAVR evaluation. DS-CTA additionally provided the necessary angiographic imaging of the aorta and peripheral access vessels while still maintaining a lower radiation dose. We propose that a single non-ECG gated FLASH DS-CTA could be utilized to provide all the necessary pre-TAVR imaging information without a gated CT scan.

Volume variation may be a relevant metric in the study of aneurysm pulsatility: Results of a pilot study

Purpose Intracranial aneurysms are frequent with a prevalence estimated over 2–5% in the general population. They usually remain silent until rupture occurs with a mortality rate of 35–50% and a high rate of morbidity including long-term disability. However, preventative treatments have their own risk of complication and morbi-mortality rate including stroke and hemorrhage. ECG-gated 4D CTA allows acquisition of time-resolved 3D reconstructions. The aim of our study is to evaluate different intracranial aneurysm metrics over cardiac cycle using ECG-gated 4D-CTA. Materials and methods ECG-gated 4D-CTA datasets were acquired in patients presenting with intracranial aneurysms. Seven aneurysm metrics including height, length, width, ostium area, volume aspect ratio and volume ostium ratio were analyzed for different cardiac phases. An intra-reader agreement, inter-reader agreement and inter-cycles agreement were calculated through intraclass correlation coefficient. Results Twenty one aneurysms from 11 patients were considered for inclusion. The post-processing failed for 3 aneurysms, and eighteen aneurysms were analyzed. There were significant differences between the minimum and the maximum of every metrics during the cardiac cycle (P 0.9). Agreements between three following cardiac cycles were calculated for 6 aneurysms and was especially good for the volume (ICC > 0.9). Conclusions Aneurysm volume changes over cardiac cycle is quantitatively possible and a reproducible measurement. Further studies need to be conducted to evaluate this new parameter for intracranial aneurysm assessment.

Electrocardiography‐gated cardiac CT angiography can differentiate brachycephalic dogs with and without pulmonary valve stenosis and findings differ from transthoracic echocardiography

Pulmonary valve stenosis (PS) is one of the most commonly diagnosed congenital heart defects in dogs. Currently, transthoracic echocardiography (TTE) is the standard modality used to evaluate PS. Image acquisition by TTE can be challenging in some brachycephalic breeds of dogs. The use of echocardiographic-gated CT angiography (ECG-gated CTA) in veterinary medicine is limited. This retrospective method comparison study investigated right and left ventricular outflow diameters by sedated ECG-gated CTA and unsedated TTE in 14 brachycephalic dogs with PS and 12 brachycephalic dogs without PS. Measurements of ventricular outflow structures were made in early systole and end diastole for both modalities and then compared for significance between systolic and diastolic phases, as well as between the two modalities. Ratios of the pulmonary trunk diameter to the aorta at different locations (aortic valve, aortic annulus, and ascending aorta) and in different planes (transverse, sagittal) were compared between dogs with PS and without PS, as well as within dogs, by both TTE and ECG-gated CTA. Transthoracic echocardiography and ECG-gated CTA both detected significantly greater pulmonary trunk to aorta ratios in dogs with PS at all aortic locations (P<0.05). Pulmonary valve to aortic valve ratios were significantly smaller in dogs with PS (P<0.05). Pulmonary trunk to aorta and pulmonary valve to aorta ratios were achieved with good anatomic detail using ECG-gated CTA. Ratios of the pulmonary trunk and pulmonary valve relative to the aorta may be useful to evaluate for PS using a modality that is underutilized for cardiac assessment.

320-row CT transcatheter aortic valve replacement planning with a single reduced contrast media bolus injection.

ObjectiveTo reduce the iodine load required for CT Transcatheter Aortic Valve Replacement (TAVR) planning on a 320-row scanner by acquiring the two CT TAVR steps (ECG-gated aortic root CTA and non-gated aorto-ilio-femoral CTA) within a single contrast media bolus injection.Methods50 consecutive patients (82.6±6.9 years; 56% female) were prospectively enrolled and underwent a TAVR planning using a 320-row CT, with ECG-gated aortic root CTA immediately followed by a non-gated aorto-iliac acquisition, all within a single bolus of 40-70mL of Iohexol 350mgI/mL. The Iodine load, image quality, SNR, CNR and radiation dose were compared using a Mann-Whitney test to that of 24 consecutive patients (84.3±4.8 years, 58% female) previously imaged on a 64-row scanner with a conventional two-step protocol.ResultsIodine load was reduced by 44%. All examinations were of diagnostic quality, with improvement of the aortic root CTA image quality (4.9±0.3 versus 4.6±0.5, p<0.01) and a non-significant decrease of the aorto-iliac CTA image quality (4.7±0.6 versus 4.9±0.3, p = 0.07). SNR and CNR were significantly improved in the aortic root CTA (14.0±5.3 and 10.4±4.5 versus 10.3±4.2 and 6.8±3.3, p<0.01 for both) and non-significantly higher in the aorto-iliac CTA (16.5±8.0 and 14.1±7.9 versus 14.7±5.5 and 12.5±5.0, p = 0.42 and p = 0.66). Total radiation dose was reduced by 32%.Conclusion320-row CT scanner enables a 44% reduction of iodine load in TAVR planning, while maintaining excellent aorto-ilio-femoral arterial enhancement and lowering radiation dose.

Aortic root evaluation prior to transcatheter aortic valve implantation-Correlation of manual and semi-automatic measurements.

BackgroundPre-procedural TAVI planning requires highly sophisticated and time-consuming manual measurements performed by experienced readers. Semi-automatic software may assist with partial automation of assessment of multiple parameters. The aim of this study was to evaluate differences between manual and semi-automatic measurements in terms of agreement and time.MethodsOne hundred and twenty TAVI candidates referred for the retrospectively ECG-gated CTA (2nd and 3rd generation dual source CT) were evaluated. Fully manual and semi-automatic measurements of fourteen aortic root parameters were assessed in the 20% phase of the R-R interval. Reading time was compared using paired samples t-test. Inter-software agreement was calculated using the Intraclass correlation coefficient (ICC) in a 2-way mixed effects model. Differences between manual and semi-automatic measurements were evaluated using Bland-Altman analysis.ResultsThe time needed for evaluation using semi-automatic assessment (3 min 24 s ± 1 min 7 s) was significantly lower (p<0.001) compared to a fully manual approach (6 min 31 sec ± 1 min 1 sec). Excellent inter-software agreement was found (ICC = 0.93 ± 0.0; range:0.90–0.95).The same prosthesis size from manual and semi-automatic measurements was selected in 92% of cases, when sizing was based on annular area. Prosthesis sizing based on annular short diameter and perimeter agreed in 99% and 96% cases, respectively.ConclusionUse of semi-automatic software in pre-TAVI evaluation results in comparable results in respect of measurements and selected valve prosthesis size, while necessary reading time is significantly lower.

Congenital coronary artery anomalies in adult population detected using dual source ECG-gated CTA in a single institution

Congenital anomalies of the coronary arteries (CAs) are rare and are often diagnosed incidentally during a conventional coronary angiography. Recently, the incidence of these congenital defects is on the rise particularly after the introduction of the electrocardiography (ECG) gated coronary computed tomographic angiography (CCTA). This innovative radiological screening modality has led to the most precise mapping of the course of the CAs on computed tomographic scan. The aim of the study is to determine the prevalence and describe the CAs congenital anomalies and their variations in Kuwaiti population at a single institution experience. We analysed the CCTA data obtained consecutively from 842 patients (2013-2014), retrospectively. The inclusion criteria for patients' selection were: atypical chest pain, equivocal ECG, assessment of patency of coronary stents or grafts and pre-operative screening. Information was acquiesced using a dual-source CT scanner with ECG gating. Data analysis revealed that 22 (2.61%) patients were found to have CA anomalies out of the 842 patients who underwent CCTA. Out of these CA anomalies, 13 cases showed more than two ostia, 7 cases showed the ectopic origin of a CA from opposite sinus or non-aortic sinus, 2 cases showed single coronary ostium and 1 case showed coronary artery with pulmonary fistula. Also, myocardial bridging was identified in 78 (9.26%) patients whereas ramus intermedius branch was identified in 160 (19%) patients. The prevalence of CA anomalies in Kuwait was 2.6%, which is relatively higher than previously reported studies from different countries.