Cardiovascular magnetic resonance deformation imaging: method comparison and considerations regarding reproducibility

Funding Acknowledgements

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): German Centre for Cardiovascular Research

Purpose

Myocardial Feature-Tracking (FT) deformation imaging is superior for risk-stratification compared to volumetric approaches. Since there is no clear recommendation regarding FT post-processing, we compared different FT-strain analyses with reference standard techniques, including tagging and strain encoded (SENC) magnetic resonance imaging.

Methods

FT software from 4 different vendors (TomTec/Medis/Circle(CVI)/Neosoft), tagging (Segment), and fastSENC (MyoStrain) were used to determine left ventricular global circumferential and longitudinal strains (GCS/GLS) in 12 healthy volunteers and 12 heart failure patients. Variability and agreements were assessed using intraclass correlation coefficients for absolute agreement (ICCa) and consistency (ICCc) as well as pearson correlation coefficients.

Results

For FT-GCS, consistency was excellent comparing different FT-vendors (ICCc = 0.84-0.97, r = 0.86-0.95) and compared to fSENC (ICCc = 0.78-0.89, r = 0.73-0.81). FT-GCS consistency was excellent compared to tagging (ICCc = 0.79-0.85, r = 0.74-0.77) except for TomTec (ICCc = 0.68, r = 0.72). Absolute FT-GCS agreements between FT-vendors were highest for CVI and Medis (ICCa = 0.96) and lowest for TomTec and Neosoft (ICCa = 0.32). Similarly, absolute FT-GCS agreements were excellent for CVI and Medis compared to both tagging and fSENC (ICCa = 0.84-0.88), good to excellent for Neosoft (ICCa = 0.77 and 0.64) and lowest for TomTec (ICCa = 0.41 and 0.47).

For FT-GLS, consistency was excellent (ICCc≥0.86, r≥0.76). Absolute agreements between FT-vendors were excellent (ICCa = 0.91-0.93) or good to excellent for TomTec (ICCa = 0.69-0.85). Absolute agreements (ICCa) were good (CVI 0.70, Medis 0.60) and fair (TomTec 0.41, Neosoft 0.59) compared to tagging but excellent compared to fSENC (ICCa = 0.77-0.90).

Conclusion

Although absolute agreements differ depending on deformation assessment approaches, consistency and correlation are consistently high irrespective of the method chosen, thus indicating reliable strain assessment. Further standardisation and introduction of uniform references is warranted for routine clinical implementation.

Fully automated artificial intelligence-based myocardial scar quantification for diagnostic and prognostic stratification in patients following acute myocardial infarction

Funding Acknowledgements

Type of funding sources: None.

Background Myocardial infarct size (IS) remains one of the strongest predictors of adverse cardiac events following acute myocardial infarction (AMI). Late gadolinium enhancement (LGE) cardiac magnetic resonance (CMR) can precisely quantify the extent of injury but requires manual post-processing. Whether novel user-independent artificial intelligence (AI) based fully-automated analyses may facilitate clinical workflow and deliver similar information for risk stratification is unknown.

Methods 913 AMI patients from two multi-center trials (AIDA-STEMI n = 704 with ST-elevation myocardial infarction [STEMI] and TATORT-NSTEMI n = 245 with non-ST-elevation-infarction [NSTEMI]) were included in this sub-study. IS was quantified manually using conventional software (Medis, Leiden Netherlands) and fully automated AI-based software (NeoSoft). All automatically detected IS were evaluated visually and corrected if necessary. Analyzed data were tested for agreement and prediction of major adverse clinical events (MACE) within one year after AMI.

Results Automated and manual IS were similarly associated with outcome in cox regression analyses (HR 1.05 [95% CI 1-02-1.07] p < 0.001 for automated IS and HR 1.04 [95% CI 1.02-1.06]; p < 0.001 for manual IS). Comparison of C-statistics derived area under the curve (AUC) resulted in equivalent MACE prediction (AUC 0.65 for automated vs. AUC 0.66 for manual, p = 0.53). Manual correction of the automated scar detection did not lead to an improved risk prediction of MACE (AUC 0.65 to 0.66, p = 0.43). There was good agreement of automated and manually derived IS (intraclass correlation coefficient [ICC] 0.75 [0.07-0.89]) which was further improved after manual correction of the underlying contours (ICC 0.98 [0.97-0.98]).

Conclusion AI-based software enables automated scar quantification with similar prognostic value compared to conventional methods in patients following AMI.

Fully automated cardiac assessment for diagnostic and prognostic stratification following myocardial infarction

Funding Acknowledgements

Type of funding sources: None.

Background

Cardiovascular magnetic resonance (CMR) imaging is considered the reference methodology for cardiac morphology and function but requires manual post-processing. Whether novel artificial intelligence (AI) -based automated analyses deliver similar information for risk stratification is unknown. Therefore, this study aimed to investigate feasibility and prognostic implications of AI-based analyses.

Methods

CMR data (n = 1017 patients) from two myocardial infarction multi-center trials were included. Analyses of biventricular parameters including ejection fraction (EF) were manually and automatically assessed using conventional and AI-based software. Obtained parameters entered regression analyses for prediction of major adverse clinical events (MACE) defined as death, reinfarction or congestive heart failure within one-year after the acute event.

Results

Both manual and uncorrected automated volumetric assessments showed similar impact on outcome on univariate (LVEF HR 0.93, [95% CI 0.91-0.95]; p < 0.001 for manual and HR 0.94 [0.92-0.96]; p < 0.001 for automated) and multivariable analyses (LVEF HR 0.95, [0.92-0.98]; p = 0.001 for manual and HR 0.95 [CI 0.92-0.98]; p = 0.001 for automated). Manual correction of the automated contours did not lead to improved risk prediction (LVEF AUC 0.67 automated vs. 0.68 automated corrected, p = 0.49). There was acceptable agreement (bias: 2.6%, 95% limits of agreement [LOA] -9.1-14.2%, intraclass correlation coefficient [ICC] 0.88 [0.77-0.93] for LVEF) of manual and automated volumetric assessments.

Conclusions

User independent volumetric analyses performed by fully automated software are feasible and results are equally predictive of MACE compared with conventional analyses in patients following myocardial infarction.

CMR feature tracking remote myocardial strain analyses for optimized risk prediction following acute myocardial infarction

Funding Acknowledgements

Type of funding sources: None.

Background

Cardiac magnetic resonance myocardial feature tracking (CMR-FT) derived global strain assessments provide incremental prognostic information in patients following acute myocardial infarction (AMI). Functional analyses of the remote myocardium (RM) are scarce and whether they provide an additional prognostic value in these patients is unknown.

Methods

1052 patients following acute myocardial infarction were included. CMR imaging and strain analyses as well as scar size quantification were performed after reperfusion by primary percutaneous coronary intervention. The occurrence of major adverse cardiac events (MACE) within 12 months after the index event was defined as primary clinical endpoint.

Results

Patients with MACE had significantly lower RM circumferential strain (CS) compared to those without MACE. A cut-off value for RM CS of -25.8% best identified high-risk patients (p < 0.001 on log-rank testing) and impaired RM CS was a strong predictor of MACE (HR 1.05, 95% CI 1.07-1.14, p = 0.003). RM CS provided further risk stratification amongst patients considered at risk according to established CMR parameters for 1.) patients with reduced left ventricular ejection fraction (LVEF) ≤ 35 % (p = 0.002 on log-rank testing), 2.) patients with reduced global circumferential strain (GCS) > -18,3 % (p = 0.015 on log-rank testing), and 3.) patients with large microvascular obstruction ≥ 1.46 % (p = 0.038 on log-rank testing).

Conclusion

CMR-FT derived RM CS is a useful parameter to characterize the response of RM and allows improved stratification following AMI beyond commonly used parameters, especially of high-risk patients.

564 Cardiac magnetic resonance myocardial feature tracking for optimized risk assessment after acute myocardial infarction in patients with type 2 diabetes

Objective

Type 2 diabetes mellitus (T2DM) associates with worse cardiovascular outcome following acute myocardial infarction (AMI) as compared to non-diabetic patients. Since the mechanisms behind these observations are not fully understood we aimed to quantify the underlying pathophysiology on ventricular and atrial levels and study their prognostic implications using cardiovascular magnetic resonance (CMR) quantitative feature-tracking (FT) and tissue characterization.

Research Design and Methods:

A total of 1147 consecutive patients with AMI (n = 265 with diabetes; n = 882 without diabetes) undergoing cardiac magnetic resonance (CMR) imaging in median 3 days after AMI were included in this multicenter study. Left ventricular (LV) function and volumetry included LV ejection fraction (LV-EF), global longitudinal (GLS), radial (GRS) and circumferential strain (GCS) as well as left atrial (LA) strain and strain rate parameters of LA reservoir, conduit and booster pump function. LV damage assessment included infarct size (IS), edema and microvascular obstruction (MO). The clinical study endpoint was the rate of major adverse cardiovascular events (MACE) at 12 months.

Results

T2DM patients had impaired LA reservoir (19.8 vs. 21.2%, p < 0.01) and conduit strains 7.6 vs. 9.0%, p < 0.01) but no differences in ventricular function or myocardial damage. They were at higher risk of MACE than non-diabetic patients (10.2% vs. 5.8%, p < 0.01) with the majority of MACE occurring in patients with LVEF ≥ 35%. Whilst LVEF was an independent predictor of adverse events in non-diabetic patients (p = 0.04 on multivariable analysis), LV GLS as well as LA strain emerged as independent predictors of poor prognosis in patients with diabetes (p < 0.02 on multivariable analysis). Considering patients with diabetes and LVEF ≥35% (n = 237), GLS and LA reservoir strain below median were significantly associated with higher 12-month event rates.

Conclusions

In patients with diabetes, LA and LV longitudinal strain permit optimized risk assessment early after reperfused AMI with incremental prognostic value over and above LVEF.

565 Impact of right atrial physiology on heart failure and adverse events after myocardial infarction

Background

Right ventricular (RV) function is a known predictor of adverse events in heart failure and following acute myocardial infarction (AMI). While right atrial (RA) involvement is well characterized in pulmonary arterial hypertension, its relative contributions to adverse events following AMI especially in patients with heart failure and congestion needs further evaluation.

Methods

1235 MI patients underwent CMR after primary percutaneous coronary intervention (PCI) in 15 centers across Germany (n = 795 with ST-elevation MI and 440 with non ST-elevation MI). Right atrial (RA) performance was evaluated using cardiac magnetic resonance myocardial feature tracking (CMR-FT) for the assessment of RA reservoir (total strain εs), conduit (passive strain εe), booster pump function (active strain εa) and associated strain rates (SR) in a blinded core-laboratory. The primary clinical endpoint was the occurrence of major adverse cardiac events (MACE) 12 months post MI.

Results

RA reservoir (εs p = 0.061, SRs p = 0.049) and conduit functions (εe p = 0.006, SRe p = 0.030) were impaired in patients with MACE as opposed to RA booster pump (εa p = 0.579, SRa p = 0.118) and RA volume index (p = 0.866). RA conduit function was associated with clinical onset of heart failure and MACE independently of RV systolic function (multi-variable analysis HR 0.95, 95% CI 0.91-0.99, p = 0.006) while RV systolic function was no independent prognosticator (HR 0.98, 95% CI 0.96-1.00, p = 0.055). Furthermore, RA conduit strain identified low- and high-risk groups within patients with relatively preserved and reduced RV and LV systolic functions (p < 0.019 on log rank testing).

Conclusions

Right atrial impairment is a distinct feature and independent risk factor in patients following AMI and can be easily assessed using CMR-FT derived quantification of RA strain.

P1838 Defining the Optimal Temporal and Spatial Resolution for Cardiovascular Magnetic Resonance Imaging Feature Tracking

Background

Myocardial deformation analyses using cardiovascular magnetic resonance feature tracking (CMR-FT) have incremental value in the assessment of cardiac function beyond volumetric analyses. Since guidelines do not recommend specific imaging parameters, we aimed to define optimal spatial and temporal resolutions for CMR cine images to enable reliable post-processing.

Methods

Intra- and inter-observer reproducibility was assessed in 12 healthy volunteers. Cine images were acquired with differing temporal (20, 30, 40 and 50 frames/cardiac cycle) and spatial resolutions (high in-plane 1.5x1.5mm through-plane 5mm, standard 1.8x1.8x8mm and low 3.0x3.0x10mm). CMR-FT analyses comprised left ventricular (LV) global longitudinal strain (GLS) and systolic strain rate (SRs) as well as LV circumferential and radial strains (GCS and GRS) and right ventricular (RV) GLS. Intra- and inter-observer reproducibility was assessed in all subjects.

Results

Temporal but not spatial resolution did impact absolute strain and SR. Maximum absolute changes between lowest and highest temporal resolution were as follows: 2.3% LV GLS, 2.2%

GCS, 7.2% GRS, 1.7% RV GLS and 0.32s-1 SRs. Changes of time-integrated (strain) values occurred predominantly comparing 20 and 30 frames/cardiac cycle including LV GLS, GCS and GRS (p = 0.034, p = 0.008 and p = 0.034) in highest spatial resolution settings. In contrast, time-derivatives values (SRs) changed significantly from lower temporal resolutions to 40 frames/cardiac cycle and beyond (20 to 30 p = 0.002; 30 to 40 p = 0.018; 40 to 50 frames/cardiac cycle p = 0.075) in highest spatial resolution settings. Strain reproducibility was not affected by either temporal or spatial resolution. SRs variability as assessed by coefficient of variation decreased with higher temporal resolutions.

Conclusion

Temporal but not spatial resolutions significantly affect strain and SR in CMR-FT deformation analyses. Clinical CMR-FT strain and SR analyses require minimum temporal resolutions of 30 and 40frames/cardiac cycle, respectively to ensure precise quantification of myocardial function.

567 Interplay of infarct territory related myocardial mechanics and prognostic implications following acute myocardial infarction

Background

Prognosis in acute myocardial infarction (AMI) depends on the amount of infarct related artery (IRA) subtended myocardium and associated damage but has not been described in great detail. Consequently, we sought to describe IRA associated pathophysiological consequences using cardiac magnetic resonance (CMR).

Methods

1235 AMI patients (n = 795 ST-elevation (STEMI) and 440 non-STEMI) underwent CMR following percutaneous coronary intervention. Blinded core-laboratory data were compared according to left anterior descending (LAD), left circumflex (LCx) and right coronary artery (RCA) regarding major adverse clinical events (MACE) within 12 months. Left ventricular (LV) global longitudinal/circumferential/radial (GLS/GCS/GRS) as well as left atrial (LA) total (εs), passive (εe) and active (εa) strains were determined using CMR-feature tracking. Tissue characterisation included infarct size (IS) and microvascular obstruction.

Results

LAD and LCx were associated with higher mortality compared to RCA lesions (4.6% and 4.4% vs 1.6%). LAD lesions showed largest IS (16.8%), largest ventricular (LV ejection fraction (EF) 47.4%, GLS -13.2%, GCS -20.8%) and atrial (εs 20.2%) impairment. There was less impairment in LCx (IS 11.8%, LVEF 50.8%, GLS -17.4%, GCS -25.0%, εs 20.7%) followed by RCA lesions (IS 11.3%, LVEF 50.8%, GLS -19.1%, GCS -26.6%, εs 21.7%). In AUC analyses εs (LAD, RCA) and GLS (LCx) best predicted MACE (AUC > 0.69). Multivariate analyses identified εs (p = 0.017) in LAD and GLS (p = 0.034) in LCx infarcts as independent predictors of MACE.

Conclusions

CMR allows IRA specific phenotyping and characterisation of morphologic and functional changes. These alterations carry infarct specific prognostic implications and may represent novel diagnostic and therapeutic targets following AMI.

566 Myocardial left ventricular mechanical uniformity and adverse cardiac events following myocardial infarction

Background

Despite limitations as a standalone parameter, left ventricular ejection fraction (LVEF) is the preferred measure of myocardial function and marker for post-infarction risk stratification. LV myocardial uniformity may provide superior prognostic information after acute myocardial infarction (AMI), which was subject of this study.

Methods and Results:

Consecutive patients with AMI (n = 1082; median age 63 years; 75% male) undergoing cardiac magnetic resonance (CMR) in median 3 days after infarction were included in this multicenter, observational study. Circumferential and radial uniformity ratio estimates (CURE and RURE) were derived from CMR feature-tracking as markers of mechanical uniformity (values between 0 and 1 with 1 reflecting perfect uniformity). The clinical endpoint was the 12-month rate of major adverse cardiac events (MACE), consisting of all-cause death, re-infarction, and new congestive heart failure.

Patients with MACE (n = 73) had significantly impaired CURE [0.76 (IQR 0.67-0.86) versus 0.84 (IQR 0.76-0.89); p < 0.001] and RURE [0.69 (IQR 0.60-0.79) versus 0.76 (IQR 0.67-0.83); p < 0.001] compared to patients without events. While uniformity estimates did not provide independent prognostic information in the overall cohort, CURE below the median of 0.84 emerged as an independent predictor of outcome in post-infarction patients with LVEF >35% (n = 959) even after adjustment for established prognostic markers (hazard ratio 1.99; 95% confidence interval 1.06-3.74; p = 0.033 in stepwise multivariable Cox regression analysis). In contrast, LVEF was not associated with adverse events in this subgroup of AMI patients.

Conclusions

CMR-derived estimates of mechanical uniformity are novel markers for risk assessment after AMI and CURE provides independent prognostic information in patients with preserved or only moderately reduced LVEF.

P5284Fully automated quantification of biventricular volumes and function in cardiovascular magnetic resonance: applicability to clinical routine settings

Background

Cardiovascular magnetic resonance (CMR) represents the clinical gold standard for the assessment of biventricular morphology and function. Since manual post-processing is time-consuming and prone to observer variability, efforts have been directed towards automated volumetric quantification. In this study, we sought to validate the accuracy of a novel approach providing fully automated quantification of biventricular volumes and function in a “real-world” clinical setting.

Methods

Three-hundred CMR examinations were randomly selected from the local data base. Fully automatic quantification of left ventricular (LV) mass, LV and right ventricular (RV) end-diastolic and systolic volumes (EDV/ESV), stroke volume (SV) and ejection fraction (EF) were performed overnight using commercially available software. Parameters were compared to manual assessments. Sub-group analyses were further performed according to image quality, scanner field strength, the presence of implanted aortic valves and repaired Tetralogy of Fallot (ToF).

Results

Biventricular automatic segmentation was feasible in all 300 cases. Overall agreement between fully automated and manually derived LV parameters was good (LV-EF: intra-class correlation coefficient [ICC] 0.95; bias −2.5% [SD 5.9%]), whilst RV agreement was lower (RV-EF: ICC 0.72; bias 5.8% [SD 9.6%]). Lowest agreement was observed in case of severely altered anatomy, e.g. marked RV dilation but normal LV dimensions in repaired ToF (LV parameters ICC 0.73–0.91; RV parameters ICC 0.41–0.94) and/or reduced image quality (LV parameters ICC 0.86–0.95; RV parameters ICC 0.56–0.91), which was more common on 3.0T than on 1.5T.

Conclusions

Fully automated assessment of biventricular morphology and function is robust and accurate in a clinical routine setting with good image quality and can be performed without any user interaction. However, in case of demanding anatomy (e.g. repaired ToF, severe LV hypertrophy) or reduced image quality, quality check and manual re-contouring is still required.

Acknowledgement/Funding

DZHK - German Centre for Cardiovascular Research

P5255Culprit vessel related myocardial mechanics and prognostic implications following acute myocardial infarction

Background

Prognosis in acute myocardial infarction (AMI) depends on the amount of infarct related artery (IRA) subtended myocardium and associated damage but has not been described in great detail. Consequently, we sought to describe IRA associated pathophysiological consequences using cardiac magnetic resonance (CMR).

Methods

1235 AMI patients (n=795 ST-elevation (STEMI) and 440 non-STEMI) underwent CMR following percutaneous coronary intervention. Blinded core-laboratory data were compared according to left anterior descending (LAD), left circumflex (LCx) and right coronary artery (RCA) regarding major adverse clinical events (MACE) within 12 months. Left ventricular (LV) global longitudinal/circumferential/radial (GLS/GCS/GRS) as well as left atrial (LA) total (εs), passive (εe) and active (εa) strains were determined using CMR-feature tracking. Tissue characterisation included infarct size (IS) and microvascular obstruction.

Results

LAD and LCx were associated with higher mortality compared to RCA lesions (4.6% and 4.4% vs 1.6%). LAD lesions showed largest IS (16.8%), largest ventricular (LV ejection fraction (EF) 47.4%, GLS −13.2%, GCS −20.8%) and atrial (εs 20.2%) impairment. There was less impairment in LCx (IS 11.8%, LVEF 50.8%, GLS −17.4%, GCS −25.0%, εs 20.7%) followed by RCA lesions (IS 11.3%, LVEF 50.8%, GLS −19.1%, GCS −26.6%, εs 21.7%). In AUC analyses εs (LAD, RCA) and GLS (LCx) best predicted MACE (AUC>0.69). Multivariate analyses identified εs (p=0.017) in LAD and GLS (p=0.034) in LCx infarcts as independent predictors of MACE.

Conclusions

CMR allows IRA specific phenotyping and characterisation of morphologic and functional changes. These alterations carry infarct specific prognostic implications and may represent novel diagnostic and therapeutic targets following AMI.

Acknowledgement/Funding

DZHK - German Centre for Cardiovascular Research

P3097Atrioventricular mechanical coupling and major adverse cardiac events in female patients following acute ST elevation myocardial infarction

Background

Data on sex-specific outcomes following myocardial infarction (MI) are inconclusive with some evidence suggesting association of female sex and increased major adverse clinical events (MACE). Since underlying mechanisms remain elusive, we aimed to quantify the underlying phenotype using cardiovascular magnetic resonance (CMR) quantitative deformation imaging and tissue characterisation.

Methods

Amongst 8 centres across Germany, 795 ST-elevation MI (STEMI) patients underwent post-interventional CMR imaging. CMR feature-tracking (FT) was performed in a blinded core-laboratory. Left ventricular function was quantified using ejection fraction (LVEF) and global longitudinal/circumferential/radial strains (GLS/GCS/GRS). Left atrial function was assessed by reservoir (εs), conduit (εe) and booster pump function (εa). Tissue characterisation included infarct size (IS), microvascular obstruction (MO), area at risk and myocardial salvage index (MSI). Primary endpoint was the occurrence of major adverse clinical events (MACE) within 1 year.

Results

Female sex was associated with increased MACE (HR 1.96, 95% CI 1.13–3.42, p=0.017) but not independently of baseline confounders (p=0.526) with women being older, more often diabetic and hypertensive (p<0.001) and of higher Killip-class (p=0.010). Tissue characterisation was similar between sexes. Women showed impaired atrial (εs p=0.011, εe p<0.001) but increased systolic ventricular mechanics (GLS p=0.001, LVEF p=0.048). Ventricular strain was associated with MACE irrespective of all univariate significant baseline characteristics (GLS HR 1.08, 95% CI 1.01–1.16, p=0.036 and GCS HR 1.07, 95% CI 1.00–1.14, p=0.040).

Conclusion

Atrial function is reduced in women following STEMI, while ventricular systolic function is increased. This may reflect ventricular diastolic failure with systolic compensation, which is independently associated with MACE and may add to sex-specific prognosis evaluation.

Acknowledgement/Funding

DZHK - German Centre for Cardiovascular Research

Cardiovascular magnetic resonance feature-tracking assessment of myocardial mechanics: Intervendor agreement and considerations regarding reproducibility

Aim

To assess intervendor agreement of cardiovascular magnetic resonance feature tracking (CMR-FT) and to study the impact of repeated measures on reproducibility.

Materials and methods

Ten healthy volunteers underwent cine imaging in short-axis orientation at rest and with dobutamine stimulation (10 and 20 μg/kg/min). All images were analysed three times using two types of software (TomTec, Unterschleissheim, Germany and Circle, cvi⁴², Calgary, Canada) to assess global left ventricular circumferential (Ecc) and radial (Err) strains and torsion. Differences in intra- and interobserver variability within and between software types were assessed based on single and averaged measurements (two and three repetitions with subsequent averaging of results, respectively) as determined by Bland–Altman analysis, intraclass correlation coefficients (ICC), and coefficient of variation (CoV).

Results

Myocardial strains and torsion significantly increased on dobutamine stimulation with both types of software (p<0.05). Resting Ecc and torsion as well as Ecc values during dobutamine stimulation were lower measured with Circle (p<0.05). Intra- and interobserver variability between software types was lowest for Ecc (ICC 0.81 [0.63–0.91], 0.87 [0.72–0.94] and CoV 12.47% and 14.3%, respectively) irrespective of the number of analysis repetitions. Err and torsion showed higher variability that markedly improved for torsion with repeated analyses and to a lesser extent for Err. On an intravendor level TomTec showed better reproducibility for Ecc and torsion and Circle for Err.

Conclusions

CMR-FT strain and torsion measurements are subject to considerable intervendor variability, which can be reduced using three analysis repetitions. For both vendors, Ecc qualifies as the most robust parameter with the best agreement, albeit lower Ecc values obtained using Circle, and warrants further investigation of incremental clinical merit.

•

This is the first comparison of two types of CMR-FT software resulting in clinically valuable inter-vendor agreement data.

•

Assessment of myocardial strain and torsion is feasible with both types of software at rest and with dobutamine stimulation.

•

For both vendors, Ecc qualifies as the most robust parameter with the lowest variability.

Real-time phase-contrast flow MRI of the ascending aorta and superior vena cava as a function of intrathoracic pressure (Valsalva manoeuvre)

OBJECTIVE

Real-time phase-contrast flow MRI at high spatiotemporal resolution was applied to simultaneously evaluate haemodynamic functions in the ascending aorta (AA) and superior vena cava (SVC) during elevated intrathoracic pressure (Valsalva manoeuvre).

METHODS

Real-time phase-contrast flow MRI at 3 T was based on highly undersampled radial gradient-echo acquisitions and phase-sensitive image reconstructions by regularized non-linear inversion. Dynamic alterations of flow parameters were obtained for 19 subjects at 40-ms temporal resolution, 1.33-mm in-plane resolution and 6-mm section thickness. Real-time measurements were performed during normal breathing (10 s), increased intrathoracic pressure (10 s) and recovery (20 s).

RESULTS

Real-time measurements were technically successful in all volunteers. During the Valsalva manoeuvre (late strain) and relative to values during normal breathing, the mean peak flow velocity and flow volume decreased significantly in both vessels (p < 0.001) followed by a return to normal parameters within the first 10 s of recovery in the AA. By contrast, flow in the SVC presented with a brief (1-2 heartbeats) but strong overshoot of both the peak velocity and blood volume immediately after pressure release followed by rapid normalization.

CONCLUSION

Real-time phase-contrast flow MRI may assess cardiac haemodynamics non-invasively, in multiple vessels, across the entire luminal area and at high temporal and spatial resolution.

ADVANCES IN KNOWLEDGE

Future clinical applications of this technique promise new insights into haemodynamic alterations associated with pre-clinical congestive heart failure or diastolic dysfunction, especially in cases where echocardiography is technically compromised.

Real-time phase-contrast flow MRI of haemodynamic changes in the ascending aorta and superior vena cava during Mueller manoeuvre

AIM

To evaluate the potential of real-time phase-contrast flow magnetic resonance imaging (MRI) at 40 ms resolution for the simultaneous determination of blood flow in the ascending aorta (AA) and superior vena cava (SVC) in response to reduced intrathoracic pressure (Mueller manoeuvre).

MATERIALS AND METHODS

Through-plane flow was assessed in 20 healthy young subjects using real-time phase-contrast MRI based on highly undersampled radial fast low-angle shot (FLASH) with image reconstruction by regularized non-linear inversion. Haemodynamic alterations (three repetitions per subject = 60 events) were evaluated during normal breathing (10 s), inhalation with nearly closed epiglottis (10 s), and recovery (20 s).

RESULTS

Relative to normal breathing and despite interindividual differences, reduced intrathoracic pressure by at least 30 mmHg significantly decreased the initial peak mean velocity (averaged across the lumen) in the AA by -24 ± 9% and increased the velocity in the SVC by +28 ± 25% (p < 0.0001, n = 23 successful events). Respective changes in flow volume per heartbeat were -25 ± 9% in the AA and +49 ± 44% in the SVC (p < 0.0001, n = 23). Flow parameters returned to baseline during sustained pressure reduction, while the heart rate was elevated by 10% (p < 0.0001) after the start (n = 24) and end (n = 17) of the manoeuvre.

CONCLUSIONS

Real-time flow MRI during low intrathoracic pressure non-invasively revealed quantitative haemodynamic adjustments in both the AA and SVC.

Current role of cardiac and extra-cardiac pathologies in clinically indicated cardiac computed tomography with emphasis on status before pulmonary vein isolation

PURPOSE

The aim of this study was to assess the incidence of cardiac and significant extra-cardiac findings in clinical computed tomography of the heart in patients with atrial fibrillation before pulmonary vein isolation (PVI).

MATERIALS AND METHODS

224 patients (64 ± 10 years; male 63 %) with atrial fibrillation were examined by cardiac 64-slice multidetector CT before PVI. Extra-cardiac findings were classified as "significant" if they were recommended to additional diagnostics or therapy, and otherwise as "non-significant". Additionally, cardiac findings were documented in detail.

RESULTS

A total of 724 cardiac findings were identified in 203 patients (91 % of patients). Additionally, a total of 619 extra-cardiac findings were identified in 179 patients (80 % of patients). Among these extra-cardiac findings 196 (32 %) were "significant", and 423 (68 %) were "non-significant". In 2 patients (1 %) a previously unknown malignancy was detected (esophageal cancer and lung cancer, local stage, no metastasis). 203 additional imaging diagnostics followed to clarify the "significant" findings (124 additional CT, costs 38 314.69 US dollars). Overall, there were 3.2 cardiac and 2.8 extra-cardiac findings per patient. Extra-cardiac findings appear significantly more frequently in patients over 60 years old, in smokers and in patients with a history of cardiac findings (p <0.05).

CONCLUSION

Cardiac CT scans before PVI should be screened for extracardiac incidental findings that could have important clinical implications for each patient.