Intraindividual Comparison of Dose Reduction and Coronary Calcium Scoring Accuracy Using Kilovolt-independent and Tin Filtration CT Protocols.

Purpose To investigate the ability of kilovolt-independent (hereafter, kV-independent) and tin filter spectral shaping to accurately quantify the coronary artery calcium score (CACS) and radiation dose reductions compared with the standard 120-kV CT protocol. Materials and Methods This prospective, blinded reader study included 201 participants (mean age, 60 years ± 9.8 [SD]; 119 female, 82 male) who underwent standard 120-kV CT and additional kV-independent and tin filter research CT scans from October 2020 to July 2021. Scans were reconstructed using a Qr36f kernel for standard scans and an Sa36f kernel for research scans simulating artificial 120-kV images. CACS, risk categorization, and radiation doses were compared by analyzing data with analysis of variance, Kruskal-Wallis test, Mann-Whitney test, Bland-Altman analysis, Pearson correlations, and κ analysis for agreement. Results There was no evidence of differences in CACS across standard 120-kV, kV-independent, and tin filter scans, with median CACS values of 1 (IQR, 0-48), 0.6 (IQR, 0-58), and 0 (IQR, 0-51), respectively (P = .85). Compared with standard 120-kV scans, kV-independent and tin filter scans showed excellent correlation in CACS values (r = 0.993 and r = 0.999, respectively), with high agreement in CACS risk categorization (κ = 0.95 and κ = 0.93, respectively). Standard 120-kV scans had a mean radiation dose of 2.09 mSv ± 0.84, while kV-independent and tin filter scans reduced it to 1.21 mSv ± 0.85 and 0.26 mSv ± 0.11, cutting doses by 42% and 87%, respectively (P < .001). Conclusion The kV-independent and tin filter research CT acquisition techniques showed excellent agreement and high accuracy in CACS estimation compared with standard 120-kV scans, with large reductions in radiation dose. Keywords: CT, Cardiac, Coronary Arteries, Radiation Safety, Coronary Artery Calcium Score, Radiation Dose Reduction, Low-Dose CT Scan, Tin Filter, kV-Independent Supplemental material is available for this article. © RSNA, 2024.

Diagnostic Value of Aortic Valve Calcification Levels in the Assessment of Low-Gradient Aortic Stenosis.

BACKGROUND: In patients with low-gradient aortic stenosis (AS) and low transvalvular flow, dobutamine stress echocardiography (DSE) is recommended to determine AS severity, whereas the degree of aortic valve calcification (AVC) supposedly correlates with AS severity according to current European and American guidelines. OBJECTIVES: The purpose of this study was to assess the relationship between AVC and AS severity as determined using echocardiography and DSE in patients with aortic valve area <1 cm2 and peak aortic valve velocity <4.0 m/s. METHODS: All patients underwent DSE to determine AS severity and multislice computed tomography to quantify AVC. Receiver-operating characteristics curve analysis was used to assess the diagnostic value of AVC for AS severity grading as determined using echocardiography and DSE in men and women. RESULTS: A total of 214 patients were included. Median age was 78 years (25th-75th percentile: 71-84 years) and 25% were women. Left ventricular ejection fraction was reduced (<50%) in 197 (92.1%) patients. Severe AS was diagnosed in 106 patients (49.5%). Moderate AS was diagnosed in 108 patients (50.5%; in 77 based on resting transthoracic echocardiography, in 31 confirmed using DSE). AVC score was high (≥2,000 for men or ≥1,200 for women) in 47 (44.3%) patients with severe AS and in 47 (43.5%) patients with moderate AS. AVC sensitivity was 44.3%, specificity was 56.5%, and positive and negative predictive values for severe AS were 50.0% and 50.8%, respectively. Area under the receiver-operating characteristics curve was 0.508 for men and 0.524 for women. CONCLUSIONS: Multi-slice computed tomography-derived AVC scores showed poor discrimination between grades of AS severity using DSE and cannot replace DSE in the diagnostic work-up of low-gradient severe AS.

Education level and the use of coronary computed tomography, functional testing, coronary angiography, revascularization, and outcomes-a 10-year Danish, nationwide, registry-based follow-up study.

BACKGROUND AND AIMS: Coronary computed tomography angiography (CCTA) can guide downstream preventive treatment and improve patient prognosis, but its use in relation to education level remains unexplored. METHODS: This nationwide register-based cohort study assessed all residents in Denmark between 2008-2018 without coronary artery disease (CAD) and 50-80 years of age (n = 1 469 724). Residents were divided according to four levels of education: low, lower-mid, higher-mid, and high. Outcomes were CCTA, functional testing, invasive coronary angiography (ICA), revascularization, and major adverse cardiovascular and cerebrovascular events (MACCE). RESULTS: Individuals with the lowest education level underwent CCTA (absolute risk [AR] 3.95% individuals aged ≥ 50-59, AR 3.62% individuals aged ≥ 60-69, AR 2.19% individuals aged ≥ 70-80) less often than individuals of lower-mid (AR 4.16%, AR 3.90%, AR 2.41%), higher-mid (AR 4.38%, AR 4.30%, AR 2.45%) and highest education level (AR 3.98%, AR 4.37%, AR 2.30%). Similar differences were observed for functional testing. Conversely, use of ICA, and risks of revascularization and MACCE were more common among individuals of lowest education level. Among patients examined with CCTA (n = 50 234), patients of lowest education level less often underwent functional testing and more likely initiated preventive medication, underwent ICA, revascularization, and experienced MACCE. CONCLUSION: Despite tax-financed healthcare in Denmark, individuals of lowest education level were less likely to undergo CCTA and functional testing than persons of higher education level. ICA utilization, revascularization and MACCE risks were higher for individuals of lowest education level. Among CCTA-examined patients, patients of lowest education level were more likely to initiate preventive medication and had the highest risks of revascularization and MACCE when compared to higher education level groups. These findings suggest that the preventive potential of CCTA is underutilized in individuals of lower education level, a proxy for socioeconomic status. Socioeconomic differences in CAD assessment, care, and outcomes are likely even larger without tax-financed healthcare.

AI-based, automated chamber volumetry from gated, non-contrast CT.

BACKGROUND: Accurate chamber volumetry from gated, non-contrast cardiac CT (NCCT) scans can be useful for potential screening of heart failure. OBJECTIVES: To validate a new, fully automated, AI-based method for cardiac volume and myocardial mass quantification from NCCT scans compared to contrasted CT Angiography (CCTA). METHODS: Of a retrospectively collected cohort of 1051 consecutive patients, 420 patients had both NCCT and CCTA scans at mid-diastolic phase, excluding patients with cardiac devices. Ground truth values were obtained from the CCTA scans. RESULTS: The NCCT volume computation shows good agreement with ground truth values. Volume differences [95% CI ] and correlation coefficients were: -9.6 [-45; 26] mL, r â€‹= â€‹0.98 for LV Total, -5.4 [-24; 13] mL, r â€‹= â€‹0.95 for LA, -8.7 [-45; 28] mL, r â€‹= â€‹0.94 for RV, -5.2 [-27; 17] mL, r â€‹= â€‹0.92 for RA, -3.2 [-42; 36] mL, r â€‹= â€‹0.91 for LV blood pool, and -6.7 [-39; 26] g, r â€‹= â€‹0.94 for LV wall mass, respectively. Mean relative volume errors of less than 7% were obtained for all chambers. CONCLUSIONS: Fully automated assessment of chamber volumes from NCCT scans is feasible and correlates well with volumes obtained from contrast study.

Imaging for implementation of heart failure guidelines.

The classification of heart failure with implications for pharmacological therapeutic interventions rests on defining ejection fraction (EF) which is an imaging parameter. Imaging can provide diagnostic clues as to aetiology of heart failure; it can also guide and help assess response to treatment. Echocardiography, CMR, cardiac computed tomography, positron emission tomography, and Tc 99 m pyrophosphate scanning provide information about the aetiology of heart failure. Further, echocardiography plays the primary role in the evaluation of LV diastolic function and the estimation of left ventricular (LV) filling pressures both at rest and with exercise during diastolic stress testing. Heart failure guidelines recognize four stages (A, B, C, and D) for heart failure. Cardiac imaging along with risk factors and clinical status is needed for identifying these stages. There are joint societal echocardiographic guidelines by American Society of Echocardiography (ASE) of Echocardiography and European Association of Cardiovascular Imaging that are applicable to the imaging of heart failure patients. There are also separate guidelines for the evaluation of patients being considered for LV assist device implantation and for multimodality imaging of patients with heart failure and preserved EF. Cardiac catheterization is needed in patients whose haemodynamic status is uncertain after clinical and echocardiographic evaluation and to evaluate for coronary artery disease. Myocardial biopsy can identify the presence of myocarditis or specific infiltrative diseases when the findings by non-invasive imaging are not conclusive.

When Echocardiography Is Challenging in Localizing Bioprosthetic Aortic Regurgitation: Dye Don't Lie.

Transesophageal echocardiography is the main imaging modality for localizing and quantifying prosthetic aortic regurgitation. We describe a case of bioprosthetic aortic paravalvular leak (PVL) where transesophageal echocardiography was inadequate; aortic root angiography and computed tomography fusion were critical in diagnosing and guiding closure. Multimodality imaging can be pivotal in localizing PVL and guiding transcatheter PVL closure. (Level of Difficulty: Intermediate.).

Role of Multimodality Imaging in Transcatheter Structural Interventions.

Cardiac imaging is the backbone for safe and optimal transcatheter structural interventions. Transthoracic echocardiogram is the initial modality to assess valvular disorders, while transesophageal echocardiogram is best to delineate the mechanism of valvular regurgitation, preprocedural assessment for transcatheter edge-to-edge repair, and for intraprocedural guidance. Cardiac computed tomography is the modality of choice for assessing calcifications, maneuvering multiplaner reconstruction of different cardiac structures, preprocedural planning for various transcatheter valve replacement, and assessing for hypoattenuated leaflet thickening and reduced leaflet motion. Cardiac magnetic resonance imaging is best known for most accurate volumetric assessment of valvular regurgitation and chamber size quantification. Cardiac positron emission tomography is the only modality that could assess active infection through using fluorine 18 fluorodeoxyglucose radiotracer.

Dynamic Imaging of Aortic Pathologies: Review of Clinical Applications and Imaging Protocols.

The past decade has seen significant advances in dynamic imaging of the aorta. Today's vascular surgeons have the opportunity to choose from a wide array of imaging modalities to evaluate different aortic pathologies. While vascular ultrasound and aortography are considered to be the bread and butter imaging modalities, newer dynamic imaging techniques provide time-resolved information in various aortic pathologies. However, despite growing evidence of their advantages in the literature, they have not been routinely adopted. In order to understand the role of these emerging modalities, one must understand their principles, advantages, and limitations in the context of various clinical scenarios. In this review, we provide an overview of dynamic imaging techniques for aortic pathologies and describe various dynamic computed tomography and magnetic resonance imaging protocols, clinical applications, and potential future directions.

Outflow cannula alignment in continuous flow left ventricular devices is associated with stroke.

We sought to evaluate whether differences in left ventricular assist device (LVAD) canula alignment are associated with stroke. There is a paucity of clinical data on contribution of LVAD canulae alignment to strokes. We conducted a retrospective analysis of patients who underwent LVAD implantation at Houston Methodist hospital from 2011 to 2016 and included those who had undergone cardiac computed tomography (CT) with contrast. LVAD graft alignment using X-ray, echocardiography, and cardiac CT was evaluated. The primary outcome was stroke within 1 year of LVAD implantation. Of the 101 patients that underwent LVAD Implantation and cardiac CT scan during the study period, 78 met inclusion criteria. The primary outcome occurred in 12 (15.4%) patients with a median time to stroke of 77 days (interquartile range: 42-132 days). Of these, 10 patients had an ischemic and two had hemorrhagic strokes. The predominant device type was Heart Mate II (94.8%). Patients with LVAD outflow cannula to aortic angle lesser than 37.5° and those with outflow graft diameter of anastomosis less than 1.5 cm (assessed by cardiac CT) had significantly higher stroke risk (p < 0.001 and p = 0.01 respectively). In HMII patients, a lower LVAD speed at the time of CT scan was associated with stroke. Further studies are needed to identify optimal outflow graft configuration to mitigate stroke risk.

Dynamic Computed Tomography Angiography is More Accurate in Diagnosing Endoleaks than Standard Triphasic Computed Tomography Angiography and Enables Targeted Embolization.

BACKGROUND: The primary objective was to compare the accuracy of dynamic computed tomography (CT) angiography (d-CTA) with standardized triphasic contrast enhanced CT angiography (t-CTA) in diagnosing endoleak type after endovascular aortic repair (EVAR) using digital subtraction angiography (DSA) as reference standard. The secondary objective was to study the impact of d-CTA on image fusion-guided endoleak embolization. METHODS: A retrospective review of patients who underwent d-CTA imaging after EVAR between March 2019 and July 2021 was performed. Deidentified images were independently reviewed by two-two blinded readers to document endoleak type and target vessels. An impact of d-CTA-guided embolization was evaluated by a number of planning angiograms, radiation exposure, and accuracy of target vessel overlay. RESULTS: During the study period, 52 patients underwent d-CTA and 19 had all 3 modalities available for analysis. DSA imaging confirmed 4 (21.0%) type-I, 14 (73.7%) type-II, and 1 (5.3%) type-III endoleak. Findings from d-CTA matched with DSA in 19/19 cases (100%), whereas t-CTA matched in 14/19 cases (73.7%). In type-II endoleaks, the number of target vessels identified by d-CTA, t-CTA, and DSA were 23, 17, and 16, respectively. Mean dose-length product from d-CTA and t-CTA was 1,445 ± 551 and 1,612 ± 530 mGy × cm (P = 0.26). Nine patients underwent d-CTA-guided type-II endoleak embolization, using a median of 1 (range: 1-4) planning angiogram before embolization using 21.6 (± 8.7)% of total procedural radiation dose. Target vessel overlay was accurate in 9/9 (100%) cases. CONCLUSIONS: Dynamic, time-resolved CTA is more accurate compared to standardized triphasic contrast enhanced CTA in diagnosing endoleak type after EVAR. In type-II endoleak, d-CTA better identified target vessels and enabled safe, targeted embolization.

Dynamic, Time-Resolved CT Angiography After EVAR: A Quantitative Approach to Accurately Characterize Aortic Endoleak Type and Identify Inflow Vessels.

PURPOSE: Our purpose was to study the accuracy of dynamic computed tomography angiography (d-CTA) in characterizing endoleak type, inflow vessels as compared with digital subtraction angiography (DSA) using qualitative and quantitative analysis. METHODS: Between March 2019 and January 2021, all patients who underwent d-CTA imaging after EVAR were retrospectively reviewed. Two blinded independent reviewers qualitatively reviewed d-CTA and DSA images. Quantitative region of interest (ROI) analysis was performed by measuring time-resolved contrast enhancement within the aorta and endoleak lesion(s) in the aneurysm sac. Differences between time-to-peak enhancement (Δ TTP) across different ROIs were quantified. RESULTS: A total of 48 patients underwent d-CTA during the study period, of whom 24 patients had abdominal EVAR and DSA imaging for comparison. Qualitative review of DSA imaging showed type I (n=4), type II (n=16), and type III (n=2) and no endoleak (n=2). In 23 of 24 patients (95.8%), d-CTA findings correlated with DSA findings for endoleak type. One patient had a type III endoleak that was demonstrated only in d-CTA (arising from defect in polymer sealing ring of Ovation stent graft) imaging. In type II endoleak cases, d-CTA identified more inflow vessels than DSA imaging (33 vs 21 vessels, p=0.010). Quantitative analysis showed mean (±SD) Δ TTP values for type I endoleak as 1.8 (±1.8) seconds, type II as 9.6 (±3.5) seconds, and for type III endoleak as 5.6 (±1.3) seconds. CONCLUSION: Dynamic CTA can accurately characterize aortic endoleak type, inflow vessels as compared with DSA imaging. Quantitative parameters such as Δ TTP enhancement can help better differentiate endoleak types and provide an objective approach to endoleak diagnosis.

Late Transcatheter Aortic Valve Thrombosis Leading to Cardiogenic Shock.

A 67-year-old woman with prior transcatheter aortic valve replacement presented with worsening dyspnea. Imaging revealed transcatheter aortic valve thrombosis and aortic stenosis. Despite oral anticoagulation, she progressively deteriorated and developed cardiogenic shock. We highlight the Heart Team's role in treating this unusual late thrombosis. (Level of Difficulty: Intermediate.).

Sex differences in machine learning computed tomography-derived fractional flow reserve.

Coronary computed tomography angiography (CCTA) derived machine learning fractional flow reserve (ML-FFRCT) can assess the hemodynamic significance of coronary artery stenoses. We aimed to assess sex differences in the association of ML-FFRCT and incident cardiovascular outcomes. We studied a retrospective cohort of consecutive patients who underwent clinically indicated CCTA and single photon emission computed tomography (SPECT). Obstructive stenosis was defined as ≥ 70% stenosis severity in non-left main vessels or ≥ 50% in the left main coronary. ML-FFRCT was computed using a machine learning algorithm with significant stenosis defined as ML-FFRCT < 0.8. The primary outcome was a composite of death or non-fatal myocardial infarction (D/MI). Our study population consisted of 471 patients with mean (SD) age 65 (13) years, 53% men, and multiple comorbidities (78% hypertension, 66% diabetes, 81% dyslipidemia). Compared to men, women were less likely to have obstructive stenosis by CCTA (9% vs. 18%; p = 0.006), less multivessel CAD (4% vs. 6%; p = 0.25), lower prevalence of ML-FFRCT < 0.8 (39% vs. 44%; p = 0.23) and higher median (IQR) ML-FFRCT (0.76 (0.53-0.86) vs. 0.71 (0.47-0.84); p = 0.047). In multivariable adjusted models, there was no significant association between ML-FFRCT < 0.8 and D/MI [Hazard Ratio 0.82, 95% confidence interval (0.30, 2.20); p = 0.25 for interaction with sex.]. In a high-risk cohort of symptomatic patients who underwent CCTA and SPECT testing, ML-FFRCT was higher in women than men. There was no significant association between ML-FFRCT and incident mortality or MI and no evidence that the prognostic value of ML-FFRCT differs by sex.

Time-resolved, Cardiac-gated Computed Tomography After Endovascular Ascending Aortic and Arch Repair.

PURPOSE: Better time-resolved imaging of stent grafts in the ascending aorta and arch accounting for cardiac motion is necessary to understand device-related complications and endoleaks. This report describes dynamic time-resolved computed tomographic angiography (d-CTA) and its combination with electrocardiography gating (d-gated CTA) to image stent grafts in the ascending aorta and to characterize endoleaks more clearly. DESCRIPTION: d-CTA involves multiple scans acquired at different time points along the contrast enhancement curve. d-Gated CTA involves concomitant electrocardiography gating in a predefined cardiac phase minimizing motion-induced artifacts. EVALUATION: This report illustrates the utility of d-CTA and d-gated CTA in 2 clinical cases. d-CTA demonstrated a type 1A endoleak in a patient with an aortic arch aneurysm treated with total arch debranching and a thoracic stent graft. d-gated CTA demonstrated a type 1A endoleak in a patient with an ascending aortic pseudoaneurysm treated with aortic cuff placement. CONCLUSIONS: Dynamic, cardiac-gated CTA enables time-resolved angiographic imaging of the ascending aorta and arch without any cardiac motion-related artifacts. Such advanced imaging techniques help with better characterization of endoleaks after stent graft deployment in the ascending aorta and arch.

Dynamic, Time-Resolved Computed Tomography Angiography Technique to Characterize Aortic Endoleak Type, Inflow and Provide Guidance for Targeted Treatment.

PURPOSE: To illustrate dynamic, time-resolved CTA (d-CTA) imaging technique in characterizing aortic endoleak type/inflow using quantitative parameters and its value in providing image guidance for targeted treatment approach. TECHNIQUE: Dedicated endoleak protocol involved acquiring multiple time-resolved contrast enhanced scans using third-generation CT scanner (Somatom Force®, Siemens Healthineers). Parameters such as scan field of view (FOV), kV, number/timing of scans were customized based on patient's body-mass-index, timing bolus, and prior imaging findings. D-CTA image datasets were evaluated qualitatively and quantitatively using time-attenuation curves (TAC) analysis after motion correction using a dedicated software (syngo.via®, Siemens). D-CTA findings from 4 illustrative cases demonstrating type I, type II (inferior mesenteric and lumbar artery inflow), and type III endoleak were illustrated. TAC analysis with time to peak parameter enabled better characterization of endoleak type and inflow. During endoleak intervention, target vessels from d-CTA images were electronically annotated and overlaid on fluoroscopy using 2D-3D image fusion to provide image guidance for targeted treatment. CONCLUSION: D-CTA imaging with TAC analysis characterizes aortic endoleak type and inflow, in addition to providing image guidance for targeted endoleak treatment. Such dynamic, time-resolved imaging techniques may provide further insights into understanding aortic endoleak that remains an Achilles heel for endovascular aortic aneurysm repair.

Outcomes of patients with moderate-to-severe Ischemia excluded from the ischemia trial.

BACKGROUND: The International Study of Comparative Health Effectiveness with Medical and Invasive Approaches (ISCHEMIA) trial showed no difference in outcomes between medical therapy vs coronary revascularization in the management of patients with stable coronary artery disease. We aimed to determine the percentage of patients with at least moderate ischemia that would have been eligible for enrollment and evaluate the outcomes of those who would not. METHODS: Consecutive patients who underwent cardiac single-photon emission computed tomography (SPECT) between April 2016 and September 2019 were identified and all-cause mortality was determined. RESULTS: There were a total of 1508 patients (mean age 67 ± 11.6 years, 69.5% males) with any perfusion defect on SPECT. Patients had a high prevalence of cardiac risk factors (73.4% with hypertension and 54.4% with diabetes mellitus.) Nearly half (709, 47%) had moderate-to-severe ischemia but over two-thirds (479/709, 66.3%) had at least one ISCHEMIA trial exclusion criteria. Patients meeting ISCHEMIA enrollment criteria had a significantly lower all-cause mortality than those who would have been excluded (3.91% vs. 11.3%, respectively, P < .001). CONCLUSION: Our results show that ISCHEMIA selected a relatively small subset of lower risk patients among the larger higher risk group of patients with moderate-to-severe ischemia typical to most cardiology centers.

Prognostic Value of Computed Tomography-Derived Fractional Flow Reserve Comparison With Myocardial Perfusion Imaging.

OBJECTIVES: The aim of this study was to compare the incremental prognostic value of coronary computed tomography (CT) angiography (CCTA)-derived machine learning fractional flow reserve CT (ML-FFRct) versus that of ischemia detected on single-photon emission-computed tomography (SPECT) myocardial perfusion imaging (MPI) on incident cardiovascular outcomes. BACKGROUND: SPECT MPI and ML-FFRct are noninvasive tools that can assess the hemodynamic significance of coronary atherosclerotic disease. METHODS: We studied a retrospective cohort of consecutive patients who underwent clinically indicated CCTA and SPECT MPI. ML-FFRct was computed using a ML prototype. The primary outcome was all-cause mortality and nonfatal myocardial infarction (D/MI), and the secondary outcome was D/MI and unplanned revascularization, percutaneous coronary intervention (PCI) or coronary artery bypass graft (CABG) occurring more than 90 days postimaging. Multiple nested multivariate cox regression was used to model a scenario wherein an initial anatomical assessment was followed by a functional assessment. RESULTS: A total of 471 patients (mean age: 64 ± 13 year; 53% males) were included. Comorbidities were prevalent (78% hypertension, 66% diabetes, 81% dyslipidemia). ML-FFRct was <0.8 in at least 1 proximal/midsegment was present in 41.6% of patients, and ischemia on MPI was present in 13.8%. After a median follow-up of 18 months, 7% of patients (n = 33) experienced D/MI. On multivariate Cox proportional analysis, the presence of ischemia on MPI but not ML-FFRct significantly predicted D/MI (HR: 2.3; 95% CI: 1.0-5.0; P = 0.047; or HR: 0.7; 95% CI: 0.3-1.4; P = 0.306 respectively) when added to CCTA obstructive stenosis. Furthermore, the model with SPECT ischemia had higher global chi-square result and significantly improved reclassification. Results were similar using the secondary outcome and on several sensitivity analyses. CONCLUSIONS: In a high-risk patient cohort, SPECT MPI but not ML-FFRct adds independent and incremental prognostic information to CCTA-based anatomical assessment and clinical risk factors in predicting incident outcomes.