Diagnostic accuracy and performance of artificial intelligence in measuring left atrial volumes and function on multiphasic CT in patients with atrial fibrillation.

OBJECTIVES: To evaluate the effectiveness of a novel artificial intelligence (AI) algorithm for fully automated measurement of left atrial (LA) volumes and function using cardiac CT in patients with atrial fibrillation. METHODS: We included 79 patients (mean age 63 ± 12 years; 35 with atrial fibrillation (AF) and 44 controls) between 2017 and 2020 in this retrospective study. Images were analyzed by a trained AI algorithm and an expert radiologist. Left atrial volumes were obtained at cardiac end-systole, end-diastole, and pre-atrial contraction, which were then used to obtain LA function indices. Intraclass correlation coefficient (ICC) analysis of the LA volumes and function parameters was performed and receiver operating characteristic (ROC) curve analysis was used to compare the ability to detect AF patients. RESULTS: The AI was significantly faster than manual measurement of LA volumes (4 s vs 10.8 min, respectively). Agreement between the manual and automated methods was good to excellent overall, and there was stronger agreement in AF patients (all ICCs ≥ 0.877; p < 0.001) than controls (all ICCs ≥ 0.799; p < 0.001). The AI comparably estimated LA volumes in AF patients (all within 1.3 mL of the manual measurement), but overestimated volumes by clinically negligible amounts in controls (all by ≤ 4.2 mL). The AI's ability to distinguish AF patients from controls using the LA volume index was similar to the expert's (AUC 0.81 vs 0.82, respectively; p = 0.62). CONCLUSION: The novel AI algorithm efficiently performed fully automated multiphasic CT-based quantification of left atrial volume and function with similar accuracy as compared to manual quantification. Novel CT-based AI algorithm efficiently quantifies left atrial volumes and function with similar accuracy as manual quantification in controls and atrial fibrillation patients. KEY POINTS: • There was good-to-excellent agreement between manual and automated methods for left atrial volume quantification. • The AI comparably estimated LA volumes in AF patients, but overestimated volumes by clinically negligible amounts in controls. • The AI's ability to distinguish AF patients from controls was similar to the manual methods.

Optimization of contrast material administration for coronary CT angiography using a software-based test-bolus evaluation algorithm.

OBJECTIVES: To evaluate the benefit of a prototype circulation time-based test bolus evaluation algorithm for the individualized optimal timing of contrast media (CM) delivery in patients undergoing coronary CT angiography (CCTA). METHODS: Thirty-two patients (62 ± 16 years) underwent CCTA using a prototype bolus evaluation tool to determine the optimal time-delay for CM administration. Contrast attenuation, signal-to-noise ratio (SNR), objective, and subjective image quality were evaluated by two independent radiologists. Results were compared to a control cohort (matched for age, sex, body mass index, and tube voltage) of patients who underwent CCTA using the generic test bolus peak attenuation +4 s protocol as scan delay. RESULTS: In the study group, the mean time delay to CCTA acquisition was significantly longer (26.0 ± 2.9 s) compared to the control group (23.1 ± 3.5 s; p < 0.01). In the study group, SNR improvement was seen in the right coronary artery (17.5 vs 13; p = 0.028), the left main (15.3 vs 12.3; p = 0.027), and the left anterior descending artery (18.5 vs 14.1; p = 0.048). Subjective image quality was rated higher in the study group (4.75 ± 0.7 vs 3.64 ± 0.5; p < 0.001). CONCLUSIONS: The prototype test bolus evaluation algorithm provided a reliable patient-specific scan delay for CCTA that ensured homogenous vascular attenuation, improvement in objective and subjective image quality, and avoidance of beam hardening artifacts. ADVANCES IN KNOWLEDGE: The prototype contrast bolus evaluation and optimization tool estimated circulation time-based time-delay improves the overall quality of CCTA.

Efficacy and safety of coronary computed tomography angiography in patients with a high clinical likelihood of obstructive coronary artery disease.

BACKGROUND: The CAT-CAD trial showed that coronary computed tomography angiography (CTA) in patients with a high prevalence of coronary artery disease (CAD) and indications for invasive coronary angiography (ICA) reduces the number of patients undergoing ICA by two-thirds and nearly eradicates non-actionable ICAs. However, the long-term benefits of this non-invasive strategy remain unknown. AIMS: To evaluate the long-term efficacy and safety of a non-invasive strategy employing coronary CTA vs. ICA as the first-line imaging test in stable patients with a high clinical likelihood of obstruc-tive CAD. METHODS: The long-term outcomes were evaluated for 36 months following randomization and included the efficacy outcome (analyzed as the composite of major adverse cardiovascular events (MACE): all-cause death, acute coronary syndrome, unplanned coronary revascularization, urgent hospitalization for a cardiovascular reason, a stroke) and the safety outcome (analyzed as a cumulative incidence of serious adverse events). RESULTS: One hundred and twenty participants at a mean age of 60.6 (7.9) years (female, 35.0%) were randomized with an allocation ratio of 1:1 to coronary CTA and direct ICA as the first-line anatomical test for suspected obstructive CAD. There were no significant differences between both diagnostic strategies neither in terms of the long-term efficacy (MACE occurrence: 15.5% in coronary CTA group vs. 16.7% in ICA group; log-rank P = 0.89) nor the long-term safety (cumulative number of serious adverse events: 36 vs. 38; P = 0.79, respectively). CONCLUSIONS: Long-term follow-up of the randomized CAT-CAD trial confirms that the strategy employing coronary CTA is an effective and safe, non-invasive, outpatient-based alternative to ICA for patients with a high clinical likelihood of obstructive CAD.

Prevalence and Associated Risk Factors of Pulmonary Embolism in Children and Young Adults With Nephrotic Syndrome: A Chinese Large Cohort Study.

PURPOSE: Nephrotic syndrome (NS) is highly associated with an increased risk of pulmonary embolism (PE) in children and young adults. However, few studies have specified the risk factors of PE in children and young adults with NS. We sought to determine the prevalence and associated factors of PE confirmed with computed tomography pulmonary angiography in Chinese children and young adults with NS. METHODS: Data from 444 children and young adults with NS who had computed tomography pulmonary angiography from December 2010 to October 2018 were retrospectively analyzed. The prevalence of PE was estimated for different age, sex, and histopathologic types of NS. Multivariable logistic regression was used to identify independent risk factors of PE in children and young adults with NS. Models incorporating the independent risk factors were evaluated using receiver operation characteristic curves. Area under the curve was used to determine the best-performing prognosticators for predicting PE. RESULTS: There were 444 patients in the study cohort (310 male patients, 134 female patients; mean age 19±3 y; range: 6 to 25 y). PE was present in 24.8% of the participants (110 of 444, 18.2% female). Children and young adult NS patients with PE tend to be older, male, to have a previous thromboembolism history and smoking, and have a higher level of proteinuria, D-dimer, and serum albumin (P<0.05 for all). Children and young adults with membranous nephropathy are likely to have a higher incidence of PE than those with other types of nephropathy. Membranous nephropathy and proteinuria were significant predictors of PE in children and young adults with NS (P<0.05 for all). The area under the curves of each model for the presence of PE in children and young adults with NS based on biochemical parameters and clinical information (model 1), adjusted for proteinuria (model 2), and adjusted for membranous nephropathy (model 3) were 0.578, 0.657, and 0.709, respectively. Compared with model 1, model 2, and model 3 showed statistically significant differences (model 1 vs. model 2, P=0.0336; model 1 vs. model 3, P=0.0268). There was no statistically significant difference between model 2 and model 3 (P=0.2947). CONCLUSION: This study identified membranous nephropathy and proteinuria as independent associated factors of PE in children and young adults with NS, which can be noted as a risk factor to guide clinician management in this population.

Feasibility and prognostic role of machine learning-based FFRCT in patients with stent implantation.

OBJECTIVES: To investigate the feasibility and prognostic implications of coronary CT angiography (CCTA) derived fractional flow reserve (FFRCT) in patients who have undergone stents implantation. METHODS: Firstly, the feasibility of FFRCT in stented vessels was validated. The diagnostic performance of FFRCT in identifying hemodynamically in-stent restenosis (ISR) in 33 patients with invasive FFR ≤ 0.88 as reference standard, intra-group correlation coefficient (ICC) between FFRCT and FFR was calculated. Secondly, prognostic value was assessed with 115 patients with serial CCTA scans after PCI. Stent characteristics (location, diameter, length, etc.), CCTA measurements (minimum lumen diameter [MLD], minimum lumen area [MLA], ISR), and FFRCT measurements (FFRCT, ΔFFRCT, ΔFFRCT/stent length) both at baseline and follow-up were recorded. Longitudinal analysis included changes of MLD, MLA, ISR, and FFRCT. The primary endpoint was major adverse cardiovascular events (MACE). RESULTS: Per-patient accuracy of FFRCT was 0.85 in identifying hemodynamically ISR. FFRCT had a good correlation with FFR (ICC = 0.84). 15.7% (18/115) developed MACE during 25 months since follow-up CCTA. Lasso regression identified age and follow-up ΔFFRCT/length as candidate variables. In the Cox proportional hazards model, age (hazard ratio [HR], 1.102 [95% CI, 1.032-1.177]; p = 0.004) and follow-up ΔFFRCT/length (HR, 1.014 [95% CI, 1.006-1.023]; p = 0.001) were independently associated with MACE (c-index = 0.856). Time-dependent ROC analysis showed AUC was 0.787 (95% CI, 0.594-0.980) at 25 months to predict adverse outcome. After bootstrap validation with 1000 resamplings, the bias-corrected c-index was 0.846. CONCLUSIONS: Noninvasive ML-based FFRCT is feasible in patients following stents implantation and shows prognostic value in predicting adverse events after stents implantation in low-moderate risk patients. KEY POINTS: • Machine-learning-based FFRCT is feasible to evaluate the functional significance of in-stent restenosis in patients with stent implantation. • Follow-up △FFRCT along with the stent length might have prognostic implication in patients with stent implantation and low-to-moderate risk after 2 years follow-up. The prognostic role of FFRCT in patients with moderate-to-high or high risk needs to be further studied. • FFRCT might refine the clinical pathway of patients with stent implantation to invasive catheterization.

Coronary Computed Tomography Angiography-Derived Fractional Flow Reserve in Patients with Anomalous Origin of the Right Coronary Artery from the Left Coronary Sinus.

OBJECTIVE: To examine the fractional flow reserve derived from computed tomographic angiography (CT-FFR) in patients with anomalous origin of the right coronary artery from the left coronary sinus (R-ACAOS) with an interarterial course, assess the relationship of CT-FFR with the anatomical features of interarterial R-ACAOS on coronary computed tomographic angiography (CCTA), and determine its clinical relevance. MATERIALS AND METHODS: Ninety-four patients with interarterial R-ACAOS undergoing CCTA were retrospectively included. Anatomic features (proximal vessel morphology [oval or slit-like], take-off angle, take-off level [below or above the pulmonary valve], take-off type, intramural course, % proximal narrowing area, length of narrowing, minimum luminal area [MLA] at systole and diastole, and vessel compression index) on CCTA associated with CT-FFR ≤ 0.80 were analyzed. Receiver operating characteristic analysis was performed to describe the diagnostic performance of CT-FFR ≤ 0.80 in detecting interarterial R-ACAOS. RESULTS: Significant differences were found in proximal vessel morphology, take-off level, intramural course, % proximal narrowing area, and MLA at diastole (all p < 0.05) between the normal and abnormal CT-FFR groups. Take-off level, intramural course, and slit-like ostium (all p < 0.05) predicted hemodynamic abnormality (CT-FFR ≤ 0.80) with accuracies of 0.69, 0.71, and 0.81, respectively. Patients with CT-FFR ≤ 0.80 had a higher prevalence of typical angina (29.4% vs. 7.8%, p = 0.025) and atypical angina (29.4% vs. 6.5%, p = 0.016). CONCLUSION: Take-off level, intramural course, and slit-like ostium were the main predictors of abnormal CT-FFR values. Importantly, patients with abnormal CT-FFR values showed a higher prevalence of typical angina and atypical angina, indicating that CT-FFR is a potential tool to gauge the clinical relevance in patients with interarterial R-ACAOS.

Feasibility of a Single Contrast Bolus High-Pitch Pulmonary CT Angiography Protocol Followed by Low-Dose Retrospectively ECG-Gated Cardiac CT in Patients with Suspected Pulmonary Embolism.

INTRODUCTION: To prospectively evaluate the feasibility of single contrast bolus high-pitch CT pulmonary angiography (CTPA) subsequently followed by low-dose retrospectively ECG-gated cardiac CT (4D-cCT) in patients with suspected pulmonary embolism (PE) to accurately evaluate right ventricular (RV) function. MATERIALS AND METHODS: 62 patients (33 female, age 65.1 ±â€Š17.5 years) underwent high-pitch CTPA examination with 80cc of iodinated contrast material. 5 s after the end of the high-pitch CTPA study, a low-dose retrospectively ECG-gated cardiac CT examination was automatically started. The volume CT dose index (CTDI vol) and dose length product (DLP) were recorded in all patients and the effective dose was calculated. For the assessment of image quality, attenuation was measured as Hounsfield units (HUs) within various regions of interest (ROIs). These ROIs were used to calculate the signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR). Subjective image quality was assessed using a five-point Likert scale. On 4D-cCT, the ejection fraction of both ventricles (RVEF, LVEF) as well as the ratio of RVEF and LVEF (RVEF/LVEF) was assessed. The statistical difference of all parameters between the PE and non-PE group was calculated. RESULTS: The mean effective radiation dose was 4.22 ± 2.05 mSv. Attenuation measurements on CTPA showed the highest attenuation values in the main pulmonary artery (442.01 ±â€Š187.64). On 4D-cCT attenuation values were highest in the descending aorta (560.59 ±â€Š208.81). The CNR and SNR values on CTPA were highest within the main pulmonary artery (CNR = 12.43 ±â€Š4.57; SNR = 15.14 ±â€Š4.90). On 4D-cCT images, the highest SNR and CNR could be measured in the descending aorta (CNR = 10.26 ±â€Š5.57; SNR = 10.86 ±â€Š5.17). The mean LVEF was 60.73 %±â€Š14.65 %, and the mean RVEF was 44.90 %±â€Š9.54 %. The mean RVEF/LVEF was 0.79 ±â€Š0.29. There was no significant difference between the PE and non-PE group for either of the parameters. CONCLUSION: The investigated combined CTPA and 4D-cCT protocol is feasible using a single contrast bolus and allows the evaluation of RV function in patients with suspected PE. Further studies have to evaluate the additional value of this protocol regarding risk stratification in patients with PE. KEY POINTS: · High-pitch CTPA is fast enough to leave sufficient contrast material within the heart that can be used for an additional low-dose functional cardiac CT examination.. · The tube current of the evaluated 4D-cCT is reduced over the entire cardiac cycle without any full dose peak.. · Low-dose cardiac CT subsequently performed after high-pitch CTPA allows for detailed analysis of RV function.. CITATION FORMAT: · Schäfer JC, Haubenreisser H, Meyer M et al. Feasibility of a Single Contrast Bolus High-Pitch Pulmonary CT Angiography Protocol Followed by Low-Dose Retrospectively ECG-Gated Cardiac CT in Patients with Suspected Pulmonary Embolism. Fortschr Röntgenstr 2018; 190: 542 - 550.

A Novel Source of Chest Pain in the Emergency Department.

This is a case report of a patient with an unusual presentation of an inferior vena cava (IVC) filter migration with a delayed presentation, and without electrical or valvular abnormalities. We discuss considerations and potential complications from IVC filter placement from the emergency physician perspective.

ACR Appropriateness Criteria® chronic chest pain--high probability of coronary artery disease.

Imaging is valuable in determining the presence, extent, and severity of myocardial ischemia and the severity of obstructive coronary lesions in patients with chronic chest pain in the setting of high probability of coronary artery disease. Imaging is critical for defining patients best suited for medical therapy or intervention, and findings can be used to predict long-term prognosis and the likely benefit from various therapeutic options. Chest radiography, radionuclide single photon-emission CT, radionuclide ventriculography, and conventional coronary angiography are the imaging modalities historically used in evaluating suspected chronic myocardial ischemia. Stress echocardiography, PET, cardiac MRI, and multidetector cardiac CT have all been more recently shown to be valuable in the evaluation of ischemic heart disease. Other imaging techniques may be helpful in those patients who do not present with signs classic for angina pectoris or in those patients who do not respond as expected to standard management. The ACR Appropriateness Criteria(®) are evidence-based guidelines for specific clinical conditions that are reviewed every 2 years by a multidisciplinary expert panel. The guideline development and review include an extensive analysis of current medical literature from peer-reviewed journals and the application of a well-established consensus methodology (modified Delphi) to rate the appropriateness of imaging and treatment procedures by the panel. In those instances in which evidence is lacking or not definitive, expert opinion may be used to recommend imaging or treatment.

Image findings of patients with H1N1 virus pneumonia and acute respiratory failure.

RATIONALE AND OBJECTIVES: The aim of this study was to assess the findings of chest radiography and high-resolution computed tomography in patients requiring intensive care unit treatment for severe H1N1 virus pneumonia. MATERIALS AND METHODS: In 2009, 10 patients required treatment in an intensive care unit for confirmed H1N1 pneumonia. All patients underwent chest radiography and high-resolution computed tomography. All 10 patients required mechanical ventilation because of respiratory failure. Nine patients presented with severe acute respiratory distress syndrome, and one patient died. Four patients underwent extracorporeal membrane oxygenation (ECMO) therapy. The results of chest radiography and high-resolution computed tomographic scans of these patients were systematically analyzed. RESULTS: The mean age of all patients was 44.1 +/- 12.3 years. All 10 patients showed abnormal results on chest radiography. The radiographic abnormalities were bilateral and multifocal in 10 patients. The predominant radiographic findings were consolidations (n = 9), ground-glass opacities (n = 8), and reticular opacities (n = 2). The most frequent computed tomographic findings at presentation consisted of bilateral ground-glass opacities (n = 9), pleural effusion (n = 9), areas of consolidation (n = 8), interstitial marking (n = 8), and crazy paving (n = 4). All patients undergoing ECMO therapy showed extensive bilateral ground-glass opacities, multifocal areas of consolidation, and crazy paving. Pleural effusion was present in three of four patients undergoing ECMO therapy. CONCLUSION: Patients requiring treatment in an intensive care unit for severe H1N1 pneumonia are at high risk for developing acute respiratory distress syndrome and frequently require ECMO therapy.

Extra-cardiac findings at cardiac CT: experience with 1,764 patients.

To investigate incidental extra-cardiac findings (ECF) at cardiac CT based on indication and impact on patient management. We retrospectively reviewed the reports of 1,764 patients who underwent a cardiac CT study between January 1, 2004 and December 31, 2006, including 463 calcium scorings (CS), 737 coronary CT angiograms (CTA), 341 pulmonary vein stenoses (PVS), and 223 bypass grafts (CABG). ECFs were categorized by type of examination, anatomical location and clinical significance. Comparisons were made between examination types to determine if incidental findings varied by indication. There were 507 ECFs with at least one ECF in 441 patients (25.0%). By examination, there was at least 1 ECF in 79/463 CS studies (17.1%), 196/737 CTAs (26.6%), 80/341 PVSs (23.4%) and 86/223 CABGs (38.6%). In 325 patients (18.4%), the findings were considered clinically important and occurred in 60/463 (12.9%) CSs, 149/737 (20.2%) CTAs, 56/341 (16.4%) PVSs and 60/223 (26.9%) CABGs. Differences between CABG and other indications and CTA vs. CS for incidental and clinically important findings were statistically significant (p < 0.05). Extra-cardiac findings requiring follow-up occur in 18% of patients and are significantly more frequent in coronary artery CTA and coronary artery bypass studies than in calcium scoring studies.

ACR practice guideline for the performance and interpretation of cardiac computed tomography (CT).

Cardiac computed tomography (CT) is an evolving modality that includes a variety of examinations to assess the anatomy and pathology of the cardiac chambers, valves, myocardium, coronary arteries and veins, pericardium, aortic root, and central great vessels. The development of multidetector CT scanners with increasing numbers of detector rows, narrow section thicknesses, increasing scanner speeds, the ability for electrocardiographic gating, and radiation dose modulation allows the performance of CT coronary arteriography. Computed tomography coronary arteriography enables the assessment of multiple types of cardiac pathology, including intraluminal coronary arterial plaque formation, coronary artery stenosis, congenital anomalies, coronary artery aneurysms, sequelae of cardiac ischemia, and the assessment of prior vascular interventions, while providing information about cardiac and valvular function. Noncardiac structures included in cardiac CT examinations must also be evaluated. This guideline attempts to maximize the probability of detecting cardiac abnormalities with cardiac CT. American College of Radiology requirements for physicians and personnel performing examinations are also addressed and will become applicable by July 1, 2008.