Invasive fractional-flow-reserve prediction by coronary CT angiography using artificial intelligence vs. computational fluid dynamics software in intermediate-grade stenosis.

Coronary computed angiography (CCTA) with non-invasive fractional flow reserve (FFR) calculates lesion-specific ischemia when compared with invasive FFR and can be considered for patients with stable chest pain and intermediate-grade stenoses according to recent guidelines. The objective of this study was to compare a new CCTA-based artificial-intelligence deep-learning model for FFR prediction (FFRAI) to computational fluid dynamics CT-derived FFR (FFRCT) in patients with intermediate-grade coronary stenoses with FFR as reference standard. The FFRAI model was trained with curved multiplanar-reconstruction CCTA images of 500 stenotic vessels in 413 patients, using FFR measurements as the ground truth. We included 37 patients with 39 intermediate-grade stenoses on CCTA and invasive coronary angiography, and with FFRCT and FFR measurements in this retrospective proof of concept study. FFRAI was compared with FFRCT regarding the sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and diagnostic accuracy for predicting FFR ≤ 0.80. Sensitivity, specificity, PPV, NPV, and diagnostic accuracy of FFRAI in predicting FFR ≤ 0.80 were 91% (10/11), 82% (23/28), 67% (10/15), 96% (23/24), and 85% (33/39), respectively. Corresponding values for FFRCT were 82% (9/11), 75% (21/28), 56% (9/16), 91% (21/23), and 77% (30/39), respectively. Diagnostic accuracy did not differ significantly between FFRAI and FFRCT (p = 0.12). FFRAI performed similarly to FFRCT for predicting intermediate-grade coronary stenoses with FFR ≤ 0.80. These findings suggest FFRAI as a potential non-invasive imaging tool for guiding therapeutic management in these stenoses.

Magnetic resonance relaxometry of the liver - a new imaging biomarker to assess right heart failure in pulmonary hypertension.

BACKGROUND: Right heart failure (RHF) in pulmonary hypertension (PH) patients is manifested by increased right atrial (RA) pressure. We hypothesized liver relaxation times measured at cardiovascular magnetic resonance (CMR) can be used to noninvasively assess increased right-sided filling pressure. METHODS: Forty-five consecutive patients, that is, 37 PH patients and 8 chronic thromboembolic pulmonary disease patients without PH underwent right heart catheterization and CMR. CMR findings were compared to 40 control subjects. Native T1, T2, and extracellular volume (ECV) liver values were measured on the cardiac maps. RESULTS: Patients with increased RA pressure (i.e.,≥8 mm Hg)(n = 19, RA+ group) showed higher NT-proBNP and CRP values, lower LVEF, MAPSE values, larger atrial size, and higher native T1 and T2 values of the myocardium than patients with normal RA pressure (RA- group, n = 26). Liver T1, T2 and ECV was significantly higher in RA+ than RA- patients and controls, that is, T1: 684 ± 129 ms vs 563 ± 72 ms and 540 ± 34 ms; T2: 60 ± 10 ms vs 49 ± 6 ms and 46 ± 4 ms; ECV: 36 ± 8% vs 29 ± 4% and 30 ± 3%. A positive correlation was found between liver T1, T2 and ECV and RA pressure, that is, r2 of 0.61, 0.82, and 0.58, respectively (p < 0.001). ROC analysis to depict increased RA pressure showed an AUC of 0.847, 0.904, 0.816, and 0.645 for liver T1, T2, NT-proNBP and gamma-glutamyl transpeptidase, respectively. Excellent intra- and inter-observer agreement was found for assessment of T1/T2/ECV liver values. CONCLUSIONS: Assessment of liver relaxation times as part of a comprehensive CMR exam in PH patients may provide valuable information with regard to the presence of passive liver congestion.

Left ventricular remodelling in mitral valve prolapse patients: implications of apical papillary muscle insertion.

AIMS: Mitral valve prolapse (MVP) causes left ventricular (LV) remodelling even in the absence of significant mitral regurgitation. To evaluate whether apical insertion of the papillary muscle (PM) influences the pattern and severity of MVP-related LV remodelling. METHODS AND RESULTS: All MVP patients who underwent CMR at our institution between December 2008 and December 2019 were included, thoroughly reviewed and grouped according to apical/non-apical PM insertion. Apical PM insertion was found in 53/92 patients (58%) and associated with mitral leaflet thickening (P < 0.01) and a trend towards higher prevalence of mitral annular disjunction (P = 0.05). Whereas no differences in ventricular volumes or ejection fraction were found, patients with apical PM insertion showed more lateral wall remodelling with mid lateral wall thinning [2.1 (1.8-2.5) vs. 4.0 (3.5-5.0) mm, P < 0.01], increased LV eccentricity and a lower GCS at this level (15 ± 3% vs. 20 ± 3%, P < 0.01). In long-axis direction, increased end-diastolic mid lateral wall angulation was found (i.e. angle <155° measured in the thinnest point of the mid lateral wall in four-chamber view) with a higher angle variation during systole (25 ± 11° vs. 17 ± 8°, P < 0.01). Remarkably, PM fibrosis was significantly more frequent in patients with apical PM insertion (i.e. 66% vs. 28%, P < 0.01). Finally, a higher burden of premature ventricular complexes (>5%) and non-sustained ventricular tachyarrhythmias was found in patients with apical PM insertion: 53% vs. 25% (P = 0.04) and 38% vs. 18% (P = 0.04), respectively. CONCLUSION: Apical PM insertion is part of the phenotypic spectrum of MVP, impacts significantly LV remodelling, and potentially may be related to increased ventricular arrhythmogenicity.

Noninvasive assessment of congestive hepatopathy in patients with constrictive pericardial physiology using MR relaxometry.

BACKGROUND: Constrictive pericarditis represents a treatable cause of mainly right heart failure (RHF), characterized by increased filling pressures and congestive hepatopathy. We hypothesized assessment of T1 and T2 liver relaxation times enables to depict liver congestion, and thus to diagnose RHF. METHODS: Cardiovascular magnetic resonance imaging (CMR) was performed in 45 pericarditis patients i.e., 25 with constrictive physiology (CP+), 20 with normal physiology (CP-), and 30 control subjects. CMR included morphologic and functional assessment of the heart and pericardium. Liver relaxation times were measured on T1 and T2 cardiac maps. RESULTS: CP+ and CP- patients were predominantly male, but CP+ patients were on average 13 years older than CP- patients (p = 0.003). T1 and T2 Liver values were significantly higher in CP+ than in CP- patients and controls, i.e. T1: 765 ± 102 ms vs 581 ± 56 ms and 537 ± 30 ms (both p < 0.001); T2: 63 ± 13 ms vs 50 ± 4 ms and 46 ± 4 ms (both p < 0.001). Extracellular volume (ECV) liver values were also increased, i.e. 42 ± 7% CP+ vs 31 ± 3% CP- and 30 ± 3% control (both p < 0.001). Using a cut-off right atrial pressure of >5 mmHg to discriminate between normal and increased pressure, native T1 liver yielded the highest AUC (0.926) at ROC analysis with a sensitivity of 79.3% and specificity of 95.6%. Gamma-glutamyl transpeptidase correlated well withT1 liver (r2 = 0.43) and ECV liver (r2 = 0.30). Excellent intra- and inter-reader agreement was found for T1, T2 and ECV measurement of the liver. CONCLUSIONS: Assessment of liver relaxation times in pericarditis patients provide valuable information on the presence of concomitant congestive hepatopathy, reflecting RHF.

CarDiac magnEtic Resonance for prophylactic Implantable-cardioVerter defibrillAtor ThErapy in Non-Ischaemic dilated CardioMyopathy: an international Registry.

AIMS: The aim of this registry was to evaluate the additional prognostic value of a composite cardiac magnetic resonance (CMR)-based risk score over standard-of-care (SOC) evaluation in a large cohort of consecutive unselected non-ischaemic cardiomyopathy (NICM) patients. METHODS AND RESULTS: In the DERIVATE registry (www.clinicaltrials.gov/registration: RCT#NCT03352648), 1000 (derivation cohort) and 508 (validation cohort) NICM patients with chronic heart failure (HF) and left ventricular ejection fraction <50% were included. All-cause mortality and major adverse arrhythmic cardiac events (MAACE) were the primary and secondary endpoints, respectively. During a median follow-up of 959 days, all-cause mortality and MAACE occurred in 72 (7%) and 93 (9%) patients, respectively. Age and >3 segments with midwall fibrosis on late gadolinium enhancement (LGE) were the only independent predictors of all-cause mortality (HR: 1.036, 95% CI: 1.0117-1.056, P < 0.001 and HR: 2.077, 95% CI: 1.211-3.562, P = 0.008, respectively). For MAACE, the independent predictors were male gender, left ventricular end-diastolic volume index by CMR (CMR-LVEDVi), and >3 segments with midwall fibrosis on LGE (HR: 2.131, 95% CI: 1.231-3.690, P = 0.007; HR: 3.161, 95% CI: 1.750-5.709, P < 0.001; and HR: 1.693, 95% CI: 1.084-2.644, P = 0.021, respectively). A composite clinical and CMR-based risk score provided a net reclassification improvement of 63.7% (P < 0.001) for MAACE occurrence when added to the model based on SOC evaluation. These findings were confirmed in the validation cohort. CONCLUSION: In a large multicentre, multivendor cohort registry reflecting daily clinical practice in NICM work-up, a composite clinical and CMR-based risk score provides incremental prognostic value beyond SOC evaluation, which may have impact on the indication of implantable cardioverter-defibrillator implantation.

Assessment of Right-Sided Heart Failure in Patients with Dilated Cardiomyopathy using Magnetic Resonance Relaxometry of the Liver.

In non-ischemic dilated cardiomyopathy (DC) patients at risk of developing right heart failure (RHF), early depiction of congestive heart failure (CHF) is pivotal to inform about the hemodynamic status and tailor medical therapy. We hypothesized increased liver relaxation times measured at routine cardiovascular magnetic resonance (CMR), reflecting passive hepatic congestion, may be a valuable imaging biomarker to depict congestive heart failure. The study cohort consisted of DC patients with LV dysfunction (i.e., ejection fraction <35%) with (n = 48) and without (n = 46) right ventricular dysfunction (RVD), defined as a right ventricular ejection fraction <35%, and >45%, respectively, and a control group (n = 40). Native T1, T2, and extracellular volume (ECV) liver values were measured on routinely acquired cardiac maps. DC+RVD patients had higher C-reactive protein, troponin I and NT-pro BNP values, and worse LV functional parameters than DC-RVD patients (all p <0.001). T1, T2 and ECV Liver values were significantly higher in DC+RVD compared to DC-RVD patients and controls, that is, T1: 675 ± 88 ms verses 538 ± 39 ms and 540 ± 34 ms; T2: 54± 8 ms versus 45 ± 5 ms and 46 ± 4 ms; ECV: 36 ± 7% versus 29 ± 4% and 30 ± 3% (all p <0.001). Gamma-glutamyltranspeptidase (GGT) correlated moderately but significantly with native T1 (r2 = 0.34), T2 (r2 = 0.27), and ECV liver (r2 = 0.23) (all p <0.001). Using right atrial (RA) pressure, as surrogate measure of RHF (i.e., RA pressure >5 mm Hg), native T1 liver yielded at ROC analysis the highest area under the curve (0.906), significantly higher than ECV liver (0.813), GGT (0.806), T2 liver (0.797), total bilirubin (0.737) and alkaline phosphatase (0.561)(p = 0.04). A T1 value of 617 ms yielded a sensitivity of 79.5% and specificity of 91.0% to depict RHF. Excellent intra-/inter-observer agreement was found for assessment of native T1/T2/ECV liver values. In conclusion, in DC patients, assessment of liver relaxation times acquired on a cardiovascular magnetic resonance exam, may provide valuable information with regard to the presence of RHF.

Assessment of long-term cardiac adaptation in adult patients with type II atrial septal defect : A cardiovascular magnetic resonance (CMR) study.

OBJECTIVES: In type II atrial septal defect (ASD) patients, the left-to-right (LR) shunt causes adaptation of the heart and circulation. The study objective was to evaluate with cardiovascular magnetic resonance imaging (CMR) the impact of LR shunt on left (LV) and right ventricular (RV) volumes, function, and myocardial strain. METHODS: Thirty-five patients (42 ± 17 years, 17 male) were compared to a control group (n = 40). Cine imaging was used to calculate ventricular volumes and ejection fraction (EF), global longitudinal (GLS) and circumferential strain (GCS), and longitudinal free wall (FWS) and interventricular septal (IVS) strain. Phase-contrast imaging was used to calculate pulmonary flow to systemic flow ratio (Qp/Qs). RESULTS: The LR shunt (Qp/Qs 2.2 ± 0.6) resulted in larger RV end-diastolic volume (EDVi) (152 ± 42 vs 82 ± 11 ml/m2), lower LV EDVi (72 ± 16 vs 83 ± 9 ml/m2), and higher RV/LV EDVi ratio (2.2 ± 0.5 vs 1.0 ± 0.1) than controls (all p < 0.001). Functionally, stroke volumes were larger in RV and lower in LV (both p < 0.001) with a strong trend toward lower RV EF in patients (p = 0.08). The LR shunt negatively impacted RV GLS (p = 0.03) but not RV GCS. Longitudinal IVS but not RV FWS were significantly lower in patients, i.e., p < 0.001, of longitudinal IVS. Shunt severity correlated with RV size and stroke volume, right atrial size, and pulmonary trunk diameter (all p < 0.001), but not with functional nor strain parameters. CONCLUSION: Long-term cardiac adaptation in ASD patients, with RV overfilling and LV underfilling, has a negative impact on systolic RV performance, a phenomenon which likely can be attributed to longitudinal dysfunction of the interventricular septum. KEY POINTS: • An LR shunt in type II ASD patients causes cardiac remodeling characterized by RV overfilling and conversely underfilling of the left ventricle. • At the long term, there is evidence of systolic dysfunction of the right ventricle in this group of patients. • Septal dysfunction underlies the observed impairment in RV function.

Feasibility of using point-of-care lung ultrasound for early triage of COVID-19 patients in the emergency room.

PURPOSE: Diagnostic value of point-of-care lung ultrasound (POCUS) in detection of coronavirus disease (COVID-19) in an emergency setting is currently unclear. In this study, we aimed to compare diagnostic performance, in terms of sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy, of POCUS lung, chest CT, and RT-PCR for clinically suspected COVID-19 infections in patients submitting to the emergency room (ER). MATERIAL AND METHODS: This retrospective study enrolled 93 patients with a suspected COVID-19 infection, admitted to the ER between March 28th and April 20th, 2020. Test subjects showed one or more symptoms of an acute respiratory infection, for which consequent COVID-19 testing was achieved using POCUS lung, chest CT, and RT-PCR. CT images were analyzed by 2 radiologists blinded to RT-PCR results. POCUS lung was performed by three emergency medical doctors, and reports were analyzed by the researcher, blinded to clinical information, US imaging, CT, and RT-PCR test results. RESULTS: Compared with RT-PCR, POCUS lung demonstrated outstanding sensitivity and NPV (93.3% and 94.1% respectively) while showing poor values for specificity, PPV, and accuracy (21.3%, 19.2%, and 33.3% respectively). In contrast, similar inquiries using chest CT as index test, excellent sensitivity, specificity, NPV, and accuracy (80.0%, 86.7%, 95.6%, and 85.6%, respectively) were reported, beside a moderate value for PPV (54.5%). CONCLUSION: POCUS may provide early ER triage with a useful, rapid, low-threshold, and safe screening tool in evaluating possible COVID-19 infections. Due to limited specificity, suggestive POCUS lung findings should be confirmed with RT-PCR or chest CT.

Frailty and Mortality in Hospitalized Older Adults With COVID-19: Retrospective Observational Study.

OBJECTIVES: To determine the association between frailty and short-term mortality in older adults hospitalized for coronavirus disease 2019 (COVID-19). DESIGN: Retrospective single-center observational study. SETTING AND PARTICIPANTS: Eighty-one patients with COVID-19 confirmed by reverse-transcriptase polymerase chain reaction (RT-PCR), at the Geriatrics department of a general hospital in Belgium. MEASUREMENTS: Frailty was graded according to the Rockwood Clinical Frailty Scale (CFS). Demographic, biochemical, and radiologic variables, comorbidities, symptoms, and treatment were extracted from electronic medical records. RESULTS: Participants (N = 48 women, 59%) had a median age of 85 years (range 65-97 years) and a median CFS score of 7 (range 2-9); 42 (52%) were long-term care residents. Within 6 weeks, 18 patients died. Mortality was significantly but weakly associated with age (Spearman r = 0.241, P = .03) and CFS score (r = 0.282, P = .011), baseline lactate dehydrogenase (LDH; r = 0.301, P = .009), lymphocyte count (r = -0.262, P = .02), and RT-PCR cycle threshold (Ct, r = -0.285, P = .015). Mortality was not associated with long-term care residence, dementia, delirium, or polypharmacy. In multivariable logistic regression analyses, CFS, LDH, and RT-PCR Ct (but not age) remained independently associated with mortality. Both age and frailty had poor specificity to predict survival. A multivariable model combining age, CFS, LDH, and viral load significantly predicted survival. CONCLUSIONS AND IMPLICATIONS: Although their prognosis is worse, even the oldest and most severely frail patients may benefit from hospitalization for COVID-19, if sufficient resources are available.

Prognostic value of cardiovascular magnetic resonance in patients with biopsy-proven systemic sarcoidosis.

OBJECTIVES: As prognosis in sarcoidosis is determined by cardiac involvement, the objective was to study the added value of cardiovascular magnetic resonance (CMR) in risk stratification. METHODS: In 114 patients (48 ± 12 years/52% male) with biopsy-proven sarcoidosis, we studied the value of clinical and CMR-derived parameters to predict future events, using sustained ventricular tachycardia, ventricular fibrillation, aborted cardiac death, implantable cardioverter-defibrillator (ICD) placement with appropriate shocks, hospitalization for heart failure, and death as composite endpoint. Median follow-up after CMR was 3.1 years (1.1-5.7 years). RESULTS: The ejection fraction (EF) was 58.2 ± 9.1% and 54.7 ± 10.8% for left ventricle (LV) and right ventricle (RV), respectively. LV late gadolinium enhancement (LGE) was present in 40 patients (35%) involving 5.1% of the LV mass (IQR, 3.0-12.0%), with concomitant RV involvement in 12 patients (11%). T2-weighting imaging and/or T2 mapping showed active disease in 14 patients. The composite endpoint was reached in 34 patients, with 7 deaths in the LGE-positive group (17.5%), versus two deaths in the LGE-negative group (2.7%) (p = 0.015). At univariate analysis, RVEF (p = 0.009), pulmonary arterial pressure (p = 0.002), and presence of LGE (p < 0.001) and LGE (% of LV) (p < 0.001) were significant. At multivariate analysis, only presence of LGE and LGE (% of LV) was significant (both p = 0.03). At Kaplan-Meier, presence of LGE and an LGE of 3% predicted event-free survival and patient survival. We found no difference in active versus inactive disease with regard to patient survival. CONCLUSION: Myocardial enhancement at LGE-CMR adds independent prognostic value in risk stratification sarcoidosis patients. In contrast, clinical as well as functional cardiac parameters lack discriminative power. KEY POINTS: • Sarcoidosis often affects the heart. • Comprehensive CMR, including T2 imaging and LGE enhancement CMR, allows to depict both active and inactive myocardial damage. • Patient prognosis in sarcoidosis is determined by the presence and severity of myocardial involvement at LGE CMR.

Accuracy and Reproducibility of Low-Dose Submillisievert Chest CT for the Diagnosis of COVID-19.

PURPOSE: To demonstrate the accuracy and reproducibility of low-dose submillisievert chest CT for the diagnosis of coronavirus disease 2019 (COVID-19) infection in patients in the emergency department. MATERIALS AND METHODS: This was a Health Insurance Portability and Accountability Act-compliant, institutional review board-approved retrospective study. From March 14 to 24, 2020, 192 patients in the emergency department with symptoms suggestive of COVID-19 infection were studied by using low-dose chest CT and real-time reverse transcription polymerase chain reaction (RT-PCR). Image analysis included the likelihood of COVID-19 infection and the semiquantitative extent of lung involvement. CT images were analyzed by two radiologists blinded to the RT-PCR results. Reproducibility was assessed using the McNemar test and intraclass correlation coefficient. Time between CT acquisition and report was measured. RESULTS: When compared with RT-PCR, low-dose submillisievert chest CT demonstrated excellent sensitivity, specificity, positive predictive value, negative predictive value, and accuracy for diagnosis of COVID-19 (86.7%, 93.6%, 91.1%, 90.3%, and 90.2%, respectively), in particular in patients with clinical symptoms for more than 48 hours (95.6%, 93.2%, 91.5%, 96.5%, and 94.4%, respectively). In patients with a positive CT result, the likelihood of disease increased from 43.2% (pretest probability) to 91.1% or 91.4% (posttest probability), while in patients with a negative CT result, the likelihood of disease decreased to 9.6% or 3.7% for all patients or those with clinical symptoms for >48 hours. The prevalence of alternative diagnoses based on chest CT in patients without COVID-19 infection was 17.6%. The mean effective radiation dose was 0.56 mSv ± 0.25 (standard deviation). Median time between CT acquisition and report was 25 minutes (interquartile range: 13-49 minutes). Intra- and interreader reproducibility of CT was excellent (all intraclass correlation coefficients ≥ 0.95) without significant bias in the Bland-Altman analysis. CONCLUSION: Low-dose submillisievert chest CT allows for rapid, accurate, and reproducible assessment of COVID-19 infection in patients in the emergency department, in particular in patients with symptoms lasting longer than 48 hours. Chest CT has the additional advantage of offering alternative diagnoses in a significant subset of patients.© RSNA, 2020.

Prognostic Value and Reproducibility of AI-assisted Analysis of Lung Involvement in COVID-19 on Low-Dose Submillisievert Chest CT: Sample Size Implications for Clinical Trials.

PURPOSE: To compare the prognostic value and reproducibility of visual versus AI-assisted analysis of lung involvement on submillisievert low-dose chest CT in COVID-19 patients. MATERIALS AND METHODS: This was a HIPAA-compliant, institutional review board-approved retrospective study. From March 15 to June 1, 2020, 250 RT-PCR confirmed COVID-19 patients were studied with low-dose chest CT at admission. Visual and AI-assisted analysis of lung involvement was performed by using a semi-quantitative CT score and a quantitative percentage of lung involvement. Adverse outcome was defined as intensive care unit (ICU) admission or death. Cox regression analysis, Kaplan-Meier curves, and cross-validated receiver operating characteristic curve with area under the curve (AUROC) analysis was performed to compare model performance. Intraclass correlation coefficients (ICCs) and Bland- Altman analysis was used to assess intra- and interreader reproducibility. RESULTS: Adverse outcome occurred in 39 patients (11 deaths, 28 ICU admissions). AUC values from AI-assisted analysis were significantly higher than those from visual analysis for both semi-quantitative CT scores and percentages of lung involvement (all P<0.001). Intrareader and interreader agreement rates were significantly higher for AI-assisted analysis than visual analysis (all ICC ≥0.960 versus ≥0.885). AI-assisted variability for quantitative percentage of lung involvement was 17.2% (coefficient of variation) versus 34.7% for visual analysis. The sample size to detect a 5% change in lung involvement with 90% power and an α error of 0.05 was 250 patients with AI-assisted analysis and 1014 patients with visual analysis. CONCLUSION: AI-assisted analysis of lung involvement on submillisievert low-dose chest CT outperformed conventional visual analysis in predicting outcome in COVID-19 patients while reducing CT variability. Lung involvement on chest CT could be used as a reliable metric in future clinical trials.

Early or deferred cardiovascular magnetic resonance after ST-segment-elevation myocardial infarction for effective risk stratification.

AIMS: In ST-segment-elevation myocardial infarction (STEMI), cardiovascular magnetic resonance (CMR) holds the potentiality to improve risk stratification in addition to Thrombolysis in Myocardial Infarction (TIMI) risk score. Nevertheless, the optimal timing for CMR after STEMI remains poorly defined. We aim at comparing the prognostic performance of three stratification strategies according to the timing of CMR after STEMI. METHODS AND RESULTS: The population of this prospective registry-based study included 492 reperfused STEMI patients. All patients underwent post-reperfusion (median: 4 days post-STEMI) and follow-up (median: 4.8 months post-STEMI) CMR. Left ventricular (LV) volumes, function, infarct size, and microvascular obstruction extent were quantified. Primary endpoint was a composite of all-death and heart failure (HF) hospitalization. Baseline-to-follow-up percentage increase of LV end-diastolic (EDV; ΔLV-EDV) ≥20% or end-systolic volumes (ESV; ΔLV-ESV) ≥15% were tested against outcome. Three multivariate models were developed including TIMI risk score plus early post-STEMI (early-CMR) or follow-up CMR (deferred-CMR) or both CMRs parameters along with adverse LV remodelling (paired-CMRs). During a median follow-up of 8.3 years, the primary endpoint occurred in 84 patients (47 deaths; 37 HF hospitalizations). Early-CMR, deferred-CMR, and paired-CMR demonstrated similar predictive value for the primary endpoint (C-statistic: 0.726, 0.728, and 0.738, respectively; P = 0.663). ΔLV-EDV ≥20% or ΔLV-ESV ≥15% were unadjusted outcome predictors (hazard ratio: 2.020 and 2.032, respectively; P = 0.002 for both) but lost their predictive value when corrected for other covariates in paired-CMR model. CONCLUSION: In STEMI patients, early-, deferred-, or paired-CMR were equivalent stratification strategies for outcome prediction. Adverse LV remodelling parameters were not independent prognosticators.

An Optimized Test Bolus Contrast Injection Protocol for Consistent Coronary Artery Luminal Enhancement for Coronary CT Angiography.

OBJECTIVES: Consistent levels of coronary artery enhancement are essential for quantitative analysis of coronary artery plaque. We studied three contrast injection protocols for coronary CT angiography (CCTA) and compared mean attenuation level and consistency of vascular contrast enhancement. We hypothesized that test bolus adjusted protocols will have a superior consistency of coronary attenuation compared to a weight-based protocol. MATERIALS AND METHODS: We prospectively evaluated a standard test bolus injection protocol (protocol 1, 32 subjects) and an optimized test bolus injection protocol (protocol 2, 59 subjects) in comparison to a body weight-based injection protocol (60 subjects). The test bolus was diluted contrast (20%-30% iopamidol 370 mixed with normal saline); peak aortic attenuation was measured and used to calculate a specific water/contrast mixture for the CCTA. The mean attenuation of the coronary lumen was measured on CCTA. Metrics of optimum arterial enhancement included the percentage of patients within a predetermined range for coronary attenuation (325-500 HU) and optimal timing with maximal ascending aortic attenuation. In addition, interpatient variation in coronary enhancement was quantified as percentage standard deviation of the attenuation. RESULTS: The mean attenuation of the coronary arteries was similar in all protocols (362, 364, and 375 HU for the weight-based, test bolus 1 and 2 protocols, respectively). The percentage standard deviations of the weight-based, test bolus 1 and 2 protocols for coronary attenuation were 25.3%, 27.1%, and 10.5%, respectively (p < 0.0001). Test optimized bolus protocol 2 yielded the highest percentage of scans within the preferred coronary attenuation range (88%, p = 0.002). In test bolus protocol 2, the contrast timing was optimal in 73% of cases compared to only 22% of cases in the body mass guided injection protocol (protocol 1, p < 0.0001). CONCLUSION: An optimized test bolus guided injection protocol resulted in a marked reduction in variation in coronary enhancement for CCTA compared to a body weight-based injection protocol.

Inter-vendor reproducibility and accuracy of segmental left ventricular strain measurements using CMR feature tracking.

OBJECTIVES: Our aim was to evaluate the inter-vendor reproducibility of cardiovascular MR feature tracking (CMR-FT) for the measurement of segmental strain (SS) of the left ventricle (LV) as well as to test the accuracy of CMR-FT to detect regional myocardial pathology. METHODS: We selected 45 patients: 15 with normal CMR findings, 15 with dilated cardiomyopathy, and 15 with acute myocardial infarction. Segmental longitudinal, circumferential, and radial strains were assessed with 4 different software. The inter-vendor difference as well as intra- and inter-observer variability was investigated. Furthermore, the accuracy of CMR-FT for the detection of structural (infarcted segments) as well as functional pathology (septal vs. lateral wall strain in left bundle branch block) was tested. RESULTS: Between vendors, there were significant differences in values for all strains (p < 0.001). The software using a non-rigid algorithm for image registration and segmentation demonstrated the best intra- as well as inter-observer variability with interclass correlation coefficient (ICC) > 0.962 and coefficient of variation (CV) < 24%. For infarct location, the same software yielded the highest area under the curve values for radial and circumferential SS (0.872 and 0.859, respectively). One of the other three software using optical flow technology performed best for longitudinal SS (0.799) and showed the largest differences in SS between septum and lateral wall in the dilated cardiomyopathy group. CONCLUSION: SS values obtained by CMR-FT are not interchangeable between vendors, and intra- and inter-observer reproducibility shows substantial variability among vendors. Overall, the different packages score relatively well to depict focal structural or functional LV pathology. KEY POINTS: • Segmental myocardial strain values obtained by CMR feature tracking are not interchangeable between different vendors. • Intra- and inter-observer reproducibility shows substantial variability among vendors. • Segmental myocardial strains measured by CMR feature tracking score relatively well to depict focal structural or functional LV pathology.

CMR and CT of the Patient With Cardiac Devices: Safety, Efficacy, and Optimization Strategies.

Cardiac magnetic resonance (CMR) and cardiac CT (CCT) have evolved into powerful diagnostic tools in the evaluation of patients with cardiovascular diseases. However, the use of these imaging techniques poses potential safety concerns for patients with implanted cardiac devices. These concerns result from the potential for electromagnetic interaction between the device and the CMR field or CCT x-ray radiation, which could lead to device heating, malfunction, or dislocation. Additionally, the presence of cardiac devices may induce significant image artifacts due to local magnetic field inhomogeneities (CMR) or photon starvation/beam hardening (CCT). In this review summarizes the safety issues regarding imaging in patients with cardiac devices. Optimization strategies to mitigate image artifacts and to improve imaging efficacy are discussed.

Coronary artery calcium scoring with photon-counting CT: first in vivo human experience.

To evaluate the performance of photon-counting detector (PCD) computed tomography (CT) for coronary artery calcium (CAC) score imaging at standard and reduced radiation doses compared to conventional energy-integrating detector (EID) CT. A dedicated cardiac CT phantom, ten ex vivo human hearts, and ten asymptomatic volunteers underwent matched EID and PCD CT scans at different dose settings without ECG gating. CAC score, contrast, and contrast-to-noise ratio (CNR) were calculated in the cardiac CT phantom. CAC score accuracy and reproducibility was assessed in the ex vivo hearts. Standard radiation dose (120 kVp, reference mAs = 80) in vivo CAC scans were compared against dose-reduced CAC scans (75% dose reduction; reference mAs = 20) for image quality and CAC score reproducibility. Interstudy agreement was assessed by using intraclass correlation (ICC), linear regression, and Bland-Altman analysis with 95% confidence interval limits of agreement (LOA). Calcium-soft tissue contrast and CNR were significantly higher for the PCD CAC scans in the cardiac CT phantom (all P < 0.01). Ex vivo hearts: CAC score reproducibility was significantly higher for the PCD scans at the lowest dose setting (50 mAs) (P = 0.002); score accuracy was similar for both detector systems at all dose settings. In vivo scans: the agreement between standard dose and low dose CAC score was significantly better for the PCD than for the EID with narrower LOA in Bland-Altman analysis, linear regression slopes closer to 1 (0.96 vs. 0.84), and higher ICC values (0.98 vs. 0.93, respectively). Phantom and in vivo human studies showed PCD may significantly improve CAC score image quality and/or reduce CAC score radiation dose while maintaining diagnostic image quality.

Quarter-millimeter spectral coronary stent imaging with photon-counting CT: Initial experience.

PURPOSE: To evaluate the performance and clinical feasibility of 0.25 mm resolution mode of a dual-energy photon-counting detector (PCD) computed tomography (CT) system for coronary stent imaging and to compare the results to state-of-the-art dual-energy energy-integrating detector (EID) CT. MATERIALS AND METHODS: Coronary stents with different diameters (2.0-4.0 mm) were examined inside a coronary artery phantom consisting of plastic tubes filled with iodine-based and gadolinium-based contrast material diluted to approximate clinical concentrations (n = 18). EID images were acquired using 2nd and 3rd generation dual-source CT systems (SOMATOM Flash and SOMATOM Force, Siemens Healthcare) at 0.60 mm (defined as standard-resolution (SR)) isotropic voxel size. Radiation-dose matched PCD images were acquired using a human prototype PCD system (Siemens Healthcare) at 0.50 mm (SR) and 0.25 mm (HR) imaging modes. Images were reconstructed using optimized convolution kernels. RESULTS: Dual-energy HR PCD images significantly better stent lumen visualization (median: 69.5%, IQR: 61.2-78.9%) over dual-energy EID, and standard-resolution PCD images (median: 53.2-57.4%, all P < 0.01). HR PCD acquisitions reconstructed at SR image voxel size showed 25.3% lower image noise compared to SR PCD acquisitions (P < 0.001). High-resolution iodine and gadolinium maps, as well as virtual monoenergetic images, were calculated from the PCD data and enabled estimation of contrast agent concentration in the lumen without interference from the coronary stent. CONCLUSION: HR spectral PCD imaging significantly improves coronary stent lumen visibility over dual-energy EID. When the PCD-HR data was reconstructed into standard voxel sizes (0.5 mm isotropic) the image noise decreased by 25% compared to SR acquisition of PCD. Both dual-energy systems were consistent in estimating contrast agent concentrations.

Left ventricular global myocardial strain assessment comparing the reproducibility of four commercially available CMR-feature tracking algorithms.

OBJECTIVES: To compare the reproducibility of cardiovascular magnetic resonance feature-tracking (CMR-FT) packages to assess global left ventricular (LV) myocardial strain. METHODS: In 45 subjects (i.e. 15 controls, 15 acute myocardial infarction, 15 dilated cardiomyopathy patients), we determined inter-vendor, inter-observer (two readers) and intra-observer reproducibility of peak systolic global radial, circumferential and longitudinal strain (GRS, GCS and GLS, respectively) comparing four commercially available software packages. Differences between vendors were assessed with analysis of variance (ANOVA), between observers and readings with intraclass correlation coefficient (ICC) and coefficient of variation (CV). RESULTS: The normalised end-diastolic volume was 91, 77 and 119 ml/m2 (median, Q1, Q3) and ejection fraction was 41 ± 14%, range 12-67%. Global longitudinal strain (GLS), global circumferential strain (GCS) and global radial strain (GRS) values were 13.9% ± 5.4% (3.9-23.8%), 12.2% ± 5.8% (1.0-25.1%) and 32.0% ± 14.7 (3.6-67.8%), respectively. ANOVA showed significant differences between vendors for GRS (p < 0.001) and GLS (p = 0.018), not for GCS (p = 0.379). No significant bias was found for both intra- and inter-observer variability. The ICC for inter- and intra-observer reproducibility ranged 0.828-0.991 and 0.902-0.997, respectively. The CV, however, ranged considerably, i.e. 4.0-28.8% and 2.8- 27.7% for inter- and intra-observer reproducibility, respectively. In particular, for GRS differences in CV values between vendors were large, i.e. 5.2-28.8% and 2.8-27.7%, for inter- and intra-observer reproducibility, respectively. CONCLUSIONS: In a cohort of subjects with a wide range of cardiac performances, GRS and GLS values are not interchangeable between vendors. Moreover, although intra- and inter-observer reproducibility amongst vendors is excellent, some vendors encounter problems to reproducibly measure global radial strain. KEY POINTS: • Different software packages are currently available for myocardial strain assessment using routinely acquired cine CMR images. • Global myocardial strain values are not interchangeable between vendors for global longitudinal and global radial strain. • Inter- and intra-observer reproducibility for global strain assessment is excellent. However, some vendors encounter problems to reproducibly measure global radial strain.