Consistency of left ventricular ejection fraction measurements in the early time course of STEMI

BACKGROUND

Early after ST-segment elevation myocardial infarction (STEMI), initial LV reshaping and hypokinesia may affect analysis of LV function. Concomitant microvascular dysfunction may affect LV function.

OBJECTIVE

To perform a comparative evaluation of left ventricular ejection fraction (LVEF) and stroke volume (SV) by different imaging modalities to assess LV function early after STEMI.

METHODS

LVEF and SV were assessed using serial imaging within 24 h and 5 days after STEMI using cineventriculography (CVG), 2-dimensional echocardiography (2DE), 2D/3D cardiovascular magnetic resonance (CMR) (2D/3D) in 82 patients.

RESULTS

2D analyses of LVEF using CVG, 2DE and 2D CMR yielded uniform results within 24 h and 5 days of STEMI. SV assessment between CVG and 2DE was comparable, whereas values for SV were higher using 2D CMR (p <  0.01 all). This was due to higher LVEDV measurements. LVEF by 2D versus 3D CMR was comparable, 3D CMR yielded higher volumetric values. This was not influenced by infarct location or infarct size.

CONCLUSIONS

2D analysis of LVEF yielded robust results across all imaging techniques implying that CVG, 2DE, and 2D CMR can be used interchangeably early after STEMI. SV measurements differed substantially between imaging techniques due to higher intermodality-differences of absolute volumetric measurements.

Diffuse myocardial fibrosis precedes subclinical functional myocardial impairment and provides prognostic information in systemic sclerosis

AIMS

Myocardial involvement is common in patients with systemic sclerosis (SSc) and causes myocardial fibrosis and subtle ventricular dysfunction. However, the temporal onset of myocardial involvement during the progression of the disease and its prognostic value are yet unknown. We used cardiovascular magnetic resonance (CMR) to investigate subclinical functional impairment and diffuse myocardial fibrosis in patients with very early diagnosis of SSc (VEDOSS) and established SSc and examined whether this was associated with mortality.

METHODS AND RESULTS

One hundred and ten SSc patients (86 established SSc, 24 VEDOSS) and 15 healthy controls were prospectively recruited. The patients were followed-up for a median duration of 7.0 years (interquartile range 6.0-7.3 years). Study subjects underwent CMR including assessment of myocardial fibrosis [native T1 and extracellular volume (ECV)] and measurement of global longitudinal (GLS) and circumferential (GCS) myocardial strain. Native T1 values and ECV were elevated in VEDOSS and SSc patients compared with controls (P < 0.001). GLS was similar in VEDOSS and controls but significantly impaired in patients with established SSc (P < 0.001). GCS was similar over all groups (P = 0.88). There were 12 deaths during follow-up. Elevated native T1 [hazard ratio (HR) 5.8, 95% confidence interval (CI): 1.7-20.4; P = 0.006] and reduced GLS (HR 6.1, 95% CI: 1.3-29.9; P = 0.038) identified subjects with increased risk of death. Only native T1 was predictive for cardiovascular mortality (P < 0.001).

CONCLUSION

Subclinical myocardial involvement first manifests as diffuse myocardial fibrosis identified by the expansion of ECV and increased native T1 in VEDOSS patients while subtle functional impairment only occurs in established SSc. Native T1 and GLS have prognostic value for all-cause mortality in SSc patients.

Parametric mapping CMR for the measurement of inflammatory reactions of the pericardium

Objectives

Although cardiovascular magnetic resonance (CMR) is increasingly used to diagnose pericardial inflammation, imaging can still be challenging using conventional CMR techniques. Parametric mapping (T1/T2 mapping) techniques have emerged as novel methods to quantify focal and global changes of the myocardium without contrast agent. The aim of the present study was to implement parametric mapping to facilitate diagnostic decision-making in pericardial inflammation.

Methods

Twenty patients with pericardial inflammation underwent CMR (1.5T system) including T1-weighted/T2-weighted imaging, T1/T2 mapping and late gadolinium enhancement. T1/T2 mapping was performed in end-diastole covering three short-axis slices. Diagnosis of pericardial inflammation was made according to recent guidelines. T1/T2 measurements were pursued by manually drawing regions of interest (ROIs) in the thickened, diseased pericardium carefully avoiding contamination by other cardiac structures. Parametric values were correlated to further markers of pericardial inflammation, such as pericardial thickening and inflammatory parameters.

Results

On average, the pericardium displayed a thickness of 4.8±1.0 mm. Mean T1 value was 1363.0±227.1 ms and T2 value was 123.3±52.6 ms, which were above patient’s myocardial values (myocardial T1: 998.7±81.0 ms, p<0.001, median 1014.46 ms; T2: 68.0±28.9 m, p<0.001) and the values of a group of four patients with chronic pericarditis (T1: 953.0±16.7 ms; T2: 63.2±10.1 ms). T1 and T2 showed a correlation to the extent of the thickened pericardium (R=0.64, p=0.002 for T1, R=0.72, p=0.005 for T2). There was no correlation of pericardial T1/T2 to blood markers of inflammation, myocardial injury (C reactive protein, troponin, creatine kinase) or further CMR parameters.

Conclusions

In patients with pericardial inflammation, parametric mapping showed elevated T1 and T2 values. Parametric mapping may help to facilitate diagnosis of pericardial inflammation if conventional parameters such as pericardial hyperintensity in T1-weighted or T2-weighted imaging or contrast agent uptake are heterogeneous.

Regional analysis of inflammation and contractile function in reperfused acute myocardial infarction by in vivo 19F cardiovascular magnetic resonance in pigs

Inflammatory cell infiltration is central to healing after acute myocardial infarction (AMI). The relation of regional inflammation to edema, infarct size (IS), microvascular obstruction (MVO), intramyocardial hemorrhage (IMH), and regional and global LV function is not clear. Here we noninvasively characterized regional inflammation and contractile function in reperfused AMI in pigs using fluorine (¹⁹F) cardiovascular magnetic resonance (CMR). Adult anesthetized pigs underwent left anterior descending coronary artery instrumentation with either 90 min occlusion (n = 17) or without occlusion (sham, n = 5). After 3 days, in surviving animals a perfluorooctyl bromide nanoemulsion was infused intravenously to label monocytes/macrophages. At day 6, in vivo ¹H-CMR was performed with cine, T2 and T2* weighted imaging, T2 and T1 mapping, perfusion and late gadolinium enhancement followed by ¹⁹F-CMR. Pigs were sacrificed for subsequent ex vivo scans and histology. Edema extent was 35 ± 8% and IS was 22 ± 6% of LV mass. Six of ten surviving AMI animals displayed both MVO and IMH (3.3 ± 1.6% and 1.9 ± 0.8% of LV mass). The ¹⁹F signal, reflecting the presence and density of monocytes/macrophages, was consistently smaller than edema volume or IS and not apparent in remote areas. The ¹⁹F signal-to-noise ratio (SNR) > 8 in the infarct border zone was associated with impaired remote systolic wall thickening. A whole heart value of ¹⁹F integral (¹⁹F SNR × milliliter) > 200 was related to initial LV remodeling independently of edema, IS, MVO, and IMH. Thus, ¹⁹F-CMR quantitatively characterizes regional inflammation after AMI and its relation to edema, IS, MVO, IMH and regional and global LV function and remodeling.

Diffuse myocardial fibrosis precedes impairment of myocardial strain in patients with systemic sclerosis

Funding Acknowledgements

Type of funding sources: None.

Background - Myocardial involvement is common in patients with systemic sclerosis (SSc) and causes myocardial fibrosis and subtle ventricular dysfunction. However, the temporal onset of myocardial involvement during the progression of the disease is yet unknown.

Purpose - To investigated the presence of subclinical functional impairment and diffuse myocardial fibrosis in patients with very early diagnosis of SSc (VEDOSS) and to compared the findings to patients with established SSc and healthy controls.

Methods - 110 SSc patients (86 with established SSc and 24 with VEDOSS) and 15 healthy controls were prospectively recruited. The study subjects underwent cardiovascular magnetic resonance on a clinical 1.5T system. Pre- and post-contrast T1 mapping was performed using a MOLLI (Modified Look-Locker Inversion Recovery) sequence. For extracellular volume (ECV) measurements, a single bolus protocol with image acquisition 15-20 min. post-contrast injection was used. For the assessment of subtle functional impairment, global longitudinal (GLS) and circumferential (GCS) myocardial strain were evaluated.

Results - Native T1 values and ECV were elevated in VEDOSS and in patients with established SSc compared to controls (p &lt; 0.001; Figure 1 A & B). GLS was similar in VEDOSS and controls but significantly reduced in patients with established SSc (p &lt; 0.001; Figure 1 C). GCS was similar over all groups (p = 0.88). Patients with clinical evidence of pulmonary or gastrointestinal involvement had higher ECV or T1 values, respectively. Patients with clinical signs of cardiac involvement had lower absolute GLS. SSc subtype, classification or disease duration were not associated with the extent of myocardial fibrosis or impaired strain.

Conclusion - Subclinical myocardial involvement first manifests as diffuse myocardial fibrosis identified by expansion of ECV and increased native T1 in VEDOSS patients while subtle functional impairment as measured by GLS only occurs in established SSc. No single clinical feature of SSc shows a strong association with subtle myocardial involvement.

Myocardial fibrosis quantification methods by cardiovascular magnetic resonance imaging with contrast-enhancement in patients with Fabry disease

Funding Acknowledgements

Type of funding sources: Public grant(s) – EU funding. Main funding source(s): National Agency for Academic Exchange (NAWA).

Background. Presence and extent of late gadolinium enhancement (LGE) in patients with Fabry disease (FD) is a predictor of adverse cardiac events. However there is no gold standard method to quantify the amount of myocardial fibrosis in cardiac magnetic resonance imaging (CMR).

Purpose. The aim of this study was to establish the most reliable and reproducible technique for quantifying LGE in patients with FD.

Methods. 68 patients with FD (40% male, 40 ± 16 years old) treated in our outpatient clinic, who underwent CMR with administration of 0.2 mmol of gadobutrol per kilogram of body weight between December 2012 and March 2019 were enrolled into the study. Presence of LGE was described in 25 patients (37%). Twenty patients underwent CMR with the same LGE sequence (Philips 1.5 Tesla, two-dimensional multi-breath-hold inversion recovery sequence) and were enrolled into further analysis. LGE quantifications were performed using gray-scale thresholds with 2, 3, 4, 5 and 6 standard deviations (SD) above the mean signal intensity for the remote myocardial tissue, full width at half maximum method (FWHM), visual assessment with threshold (VAT) and fully manual method (MM; Philips IntelliSpace Portal 10). LGE quantifications were done twice by the same observer in different time periods and once by another observer. Intraclass correlation coefficient (ICC), Bland- Altman analysis and coefficient of variation (CV) were used to assess intra- and interobserver reliability and reproducibility.

Results. The mean quantity of fibrosis mass  (in gram) in all studied patients was: 35.5 ± 18.7 at 2SD, 21.0 ± 12.8 at 3SD, 12.7 ± 8.5 at 4SD, 8.0 ± 5.7 at 5SD, 5.3 ± 4.1 at 6SD, 1.9 ± 1.8 at FWHM, 8.6 ± 7.4 at VAT and 9.1 ± 6.1 at MM. Intra-observer reliability of almost all studied LGE quantification methods was excellent, with a range of ICCs from 0.90 for 6SD to 0.95 for VAT, with one exception for FWHM, which had good intraobserver reliability (ICC 0.84; all P &lt; 0.05). Interobserver reliability was excellent for VAT (ICC 0.94) and good for all other LGE quantifications methods (range of ICCs from 0.76 for MM to 0.87 for 5SD, all P &lt; 0.05). 5SD had the lowest CV (6%) for intraobserver reproducibility and 2SD and VAT for interobserver reproducibility (35% and 38%). FWHM had the highest CV for both intra- and interobserver reproducibility (63% and 94%, accordingly).

Conclusions

1. All studied methods of LGE quantification in patients with FD and presence of myocardial fibrosis have good to excellent intra- and interobserver reliability.

2. The total amount of LGE differs in studied LGE quantifications methods. Therefore in clinical practice it is important to report which technique of LGE quantification was used and choose the same for CMR-follow up.

3. FWHM might be avoided for LGE quantification in patients with FD due to the highest intra- and interobserver variability in comparison to other available techniques.

Cardiac magnetic resonance T2 mapping and feature tracking in athlete's heart and HCM

Objectives

Distinguishing hypertrophic cardiomyopathy (HCM) from left ventricular hypertrophy (LVH) due to systematic training (athlete’s heart, AH) from morphologic assessment remains challenging. The purpose of this study was to examine the role of T2 mapping and deformation imaging obtained by cardiovascular magnetic resonance (CMR) to discriminate AH from HCM with (HOCM) or without outflow tract obstruction (HNCM).

Methods

Thirty-three patients with HOCM, 9 with HNCM, 13 strength-trained athletes as well as individual age- and gender-matched controls received CMR. For T2 mapping, GRASE-derived multi-echo images were obtained and analyzed using dedicated software. Besides T2 mapping analyses, left ventricular (LV) dimensional and functional parameters were obtained including LV mass per body surface area (LVMi), interventricular septum thickness (IVS), and global longitudinal strain (GLS).

Results

While LVMi was not significantly different, IVS was thickened in HOCM patients compared to athlete’s. Absolute values of GLS were significantly increased in patients with HOCM/HNCM compared to AH. Median T2 values were elevated compared to controls except in athlete’s heart. ROC analysis revealed T2 values (AUC 0.78) and GLS (AUC 0.91) as good parameters to discriminate AH from overall HNCM/HOCM.

Conclusion

Discrimination of pathologic from non-pathologic LVH has implications for risk assessment of competitive sports in athletes. Multiparametric CMR with parametric T2 mapping and deformation imaging may add information to distinguish AH from LVH due to HCM.

Key Points

• Structural analyses using T2 mapping cardiovascular magnetic resonance imaging (CMR) may help to further distinguish myocardial diseases.

• To differentiate pathologic from non-pathologic left ventricular hypertrophy, CMR including T2 mapping was obtained in patients with hypertrophic obstructive/non-obstructive cardiomyopathy (HOCM/HNCM) as well as in strength-trained athletes.

• Elevated median T2 values in HOCM/HNCM compared with athlete’s may add information to distinguish athlete’s heart from pathologic left ventricular hypertrophy.

Cardiovascular magnetic resonance T2* mapping for the assessment of cardiovascular events in hypertrophic cardiomyopathy

Background

Hypertrophic cardiomyopathy (HCM) is associated with an increased risk of adverse cardiac events. Beyond classic risk factors, relative myocardial ischaemia and succeeding myocardial alterations, which can be detected using either contrast agents or parametric mapping in cardiovascular magnetic resonance (CMR) imaging, have shown an impact on outcome in HCM. CMR may help to risk stratify using parametric T2* mapping. Therefore, the aim of the present study was to evaluate the association of T2* values or fibrosis with cardiovascular events in HCM.

Methods

The relationship between T2* with supraventricular, ventricular arrhythmia or heart failure was retrospectively assessed in 91 patients with HCM referred for CMR on a 1.5T MR imaging system. Fibrosis as a reference was added to the model. Patients were subdivided into groups according to T2* value quartiles.

Results

47 patients experienced an event of ventricular arrhythmia, 25 of atrial fibrillation/flutter and 17 of heart failure. T2*≤28.7 ms yielded no association with ventricular events in the whole HCM cohort. T2* of non-obstructive HCM showed a significant association with ventricular events in univariate analysis, but not in multivariate analysis. For the combined endpoint of arrhythmic events, there was already an association for the whole HCM cohort, but again only in univariate analyses. Fibrosis stayed the strongest predictor in all analyses. There was no association for T2* and fibrosis with heart failure.

Conclusions

Decreased T2* values by CMR only provide a small association with arrhythmic events in HCM, especially in non-obstructive HCM. No information is added for heart failure.

Unipolar MR elastography: Theory, numerical analysis and implementation

In MR elastography (MRE), zeroth moment balanced motion-encoding gradients (MEGs) are incorporated into MRI sequences to induce a phase shift proportional to the local displacement caused by external actuation. To maximize the signal-to-noise ratio (SNR), fractional encoding is employed, i.e., the MEG duration is reduced below the wave period. Here, gradients encode primarily the velocity of the motion-reducing encoding efficiency. Thus, in GRE-MRE, T₂ * decay and motion sensitivity have to be balanced, imposing a lower limit on repetition times (TRs). We propose to use a single trapezoidal gradient, a "unipolar gradient", to directly encode spin displacement. Such gradients cannot be used in conventional sequences as they exhibit a large zeroth moment and dephase magnetization. By time-reversing a spoiled SSFP sequence, the spoiling gradient becomes an efficient unipolar MEG. The proposed "unipolar MRE" technique benefits from this approach in three ways: first, displacement encoding is split over multiple TRs increasing motion sensitivity; second, spoiler and MEG coincide, allowing a reduction in TR; third, motion sensitivity of a typical unipolar lobe is of an order of magnitude higher than a bipolar MEG of equal duration. In this work, motion encoding using unipolar MRE is analyzed using the extended phase graph (EPG) formalism with a periodic motion propagator. As an approximation, the two-transverse TR approximation for diffusion-weighted SSFP is extended to incorporate cyclic motion. A complex encoding efficiency metric is introduced to compare the displacement fields of unipolar and conventional GRE-MRE sequences in both magnitude and phase. The derived theoretical encoding equations are used to characterize the proposed sequence using an extensive parameter study. Unipolar MRE is validated against conventional GRE-MRE in a phantom study showing excellent agreement between measured displacement fields. In addition, unipolar MRE yields significantly increased octahedral shear strain-SNR relative to conventional GRE-MRE and allows for the recovery of high stiffness inclusions, where conventional GRE-MRE fails.

P5257Prediction of 12-month cardiovascular event-free survival with regadenoson perfusion cardiovascular magnetic resonance

Background

To identify and stratify coronary artery disease (CAD) non-invasively, cardiovascular magnetic resonance (CMR) derived perfusion imaging holds a class Ia recommendation.

As Gold standard, hyperemia is induced by an intravenous application of adenosine in a body weight adapted dosage over a constant time. However, adenosin has two disadvantages: 1.) efficacy of adenosine to induce maximal hyperemia via peripheral line is imperfect and 2.) additional adenosine specific effects exclude patients having comorbidities (e.g. AV-blocks and obstructive lung disease). Fortunately, regadenoson as aselective A2A-receptor agonist has the main advantages of being easier to handle (bolus application) and to be not restricted to patients without specific comorbidities. However, there is a lack of comprehensive data on the prognostic value of regadenoson perfusion CMR to predict clinical endpoints. To assess the predictive value of regadenoson perfusion CMR, our hypothesis was, that a “negative” ischemia test result by regadenoson-CMR predicted freedom from MACE at 12 month.

Methods

676 patients, with known or suspected CAD with intermediate risk were retrospectively analyzed from May 2015 till December 2016. Cardiovascular risk factors (CVRF) like age, sex, arterial hypertension, dis-/hyperlipidemia, cigarette smoking status and diabetes were documented. All included patients received perfusion CMR (Philips 1.5 Tesla) with regadenoson (0.4 mg) and a positive ischemia test was defined as perfusion defects in ≥1,5 cardiac segments (using the 17-segment model). Major cardiovascular events (MACE) were defined as cardiovascular death, rehospitalisation due to myocardial infarction and rehospitalisation due to revascularization. The follow-up time was 12 month.

Results

80,3% (n=543) of all analyzed patients showed negative ischemia testing in CMR and were thus followed up for 12 month. From these patients, 284 (52,3%) had a pre-existing coronary artery disease. The mean age regarding only the patients with negative ischemia was 66 years (65% male and 35% female) with 1,35±1,03 CVRF. The primary endpoint (MACE) occurred in 6 patients (1,1%): 3 (0,6%) died due to cardiovascular events, 1 (0,2%) suffered from a myocardial infarction and 2 (0,4%) received coronary revascularization. Consequently, an event-free survival was correctly predicted in 98,9% of all patients. No undesirable adverse reactions have appeared.

Conclusion

Regadenoson-CMR predicts a very low MACE-rate and an event-free survival in 98,9% in over 500 patients. In our study, Regadenoson was well tolerated and no side effects were reported.

Characterizing cardiac involvement in amyloidosis using cardiovascular magnetic resonance diffusion tensor imaging

BACKGROUND

In-vivo cardiovascular magnetic resonance (CMR) diffusion tensor imaging (DTI) allows imaging of alterations of cardiac fiber architecture in diseased hearts. Cardiac amyloidosis (CA) causes myocardial infiltration of misfolded proteins with unknown consequences for myocardial microstructure. This study applied CMR DTI in CA to assess microstructural alterations and their consequences for myocardial function compared to healthy controls.

METHODS

Ten patients with CA (8 AL, 2 ATTR) and ten healthy controls were studied using a diffusion-weighed second-order motion-compensated spin-echo sequence at 1.5 T. Additionally, left ventricular morphology, ejection fraction, strain and native T1 values were obtained in all subjects. In CA patients, T1 mapping was repeated after the administration of gadolinium for extracellular volume fraction (ECV) calculation. CMR DTI analysis was performed to yield the scalar diffusion metrics mean diffusivity (MD) and fractional anisotropy (FA) as well as the characteristics of myofiber orientation including helix, transverse and E2A sheet angle (HA, TA, E2A).

RESULTS

MD and FA were found to be significantly different between CA patients and healthy controls (MD 1.77 ± 0.17 10- 3 vs 1.41 ± 0.07 10- 3 mm2/s, p <  0.001; FA 0.25 ± 0.04 vs 0.35 ± 0.03, p <  0.001). MD demonstrated an excellent correlation with native T1 (r = 0.908, p <  0.001) while FA showed a significant correlation with ECV in the CA population (r = - 0.851, p <  0.002). HA exhibited a more circumferential orientation of myofibers in CA patients, in conjunction with a higher TA standard deviation and a higher absolute E2A sheet angle. The transmural HA slope was found to be strongly correlated with the global longitudinal strain (r = 0.921, p < 0.001).

CONCLUSION

CMR DTI reveals significant alterations of scalar diffusion metrics in CA patients versus healthy controls. Elevated MD and lower FA values indicate myocardial disarray with higher diffusion in CA that correlates well with native T1 and ECV measures. In CA patients, CMR DTI showed pronounced circumferential orientation of the myofibers, which may provide the rationale for the reduction of global longitudinal strain that occurs in amyloidosis patients. Accordingly, CMR DTI captures specific features of amyloid infiltration, which provides a deeper understanding of the microstructural consequences of CA.

Navigator-free metabolite-cycled proton spectroscopy of the heart

PURPOSE

Respiratory gating in cardiac water-suppressed (WS) proton spectroscopy leads to long and unpredictable scan times. Metabolite cycling allows to perform frequency and phase correction on the water signal and, hence, offers an approach to navigator-free cardiac spectroscopy with fixed scan time. The objective of the present study was to develop and implement navigator-free metabolite-cycled cardiac proton spectroscopy (MC nonav) and compare it with standard navigator-gated WS (WS nav) and navigator-free WS (WS nonav) measurements for the assessment of triglyceride-to-water ratios (TG/W) and creatine-to-water ratios (CR/W) in the intraventricular septum of the in vivo heart.

METHODS

Navigator-free metabolite-cycled spectroscopy was implemented on a clinical 1.5T system. In vivo measurements were performed on 10 young and 5 older healthy volunteers to assess signal-to-noise ratio efficiency as well as TG/W and CR/W and the relative Cramér-Rao lower bounds for CR. The performance of the metabolite-cycled sequence was verified using simulations.

RESULTS

On average, scan times of MC nonav were 3.4 times shorter compared with WS nav, while no significant bias for TG/W was observed (coefficient of variation = 14.0%). signal-to-noise ratio efficiency of both TG and CR increased for MC nonav compared with WS nav. Relative Cramér-Rao lower bounds of CR decreased for MC nonav. Overall spectral quality was found comparable between MC nonav and WS nav, while it was inferior for WS nonav.

CONCLUSION

Navigator-free metabolite-cycled cardiac proton spectroscopy offers 3.4-fold accelerated assessment of TG/W and CR/W in the heart with preserved spectral quality when compared with navigator-gated WS scans.

Retrospective phase-based gating for cardiac proton spectroscopy with fixed scan time

BACKGROUND

Respiratory motion is a major limiting factor for spectral quality and duration of in vivo proton MR spectroscopy of the heart. Prospective navigator gating is frequently applied to minimize the effects of respiratory motion, but scan durations are subject-dependent and hence difficult to predict.

PURPOSE

To implement cardiac proton MRS with fixed scan time by employing retrospective phase-based gating and to compare the proposed method to conventional navigator-gated MRS.

STUDY TYPE

Prospective.

SUBJECTS

Eighteen healthy volunteers (29.7 ± 7.8 years).

FIELD STRENGTH/SEQUENCE

1.5, navigator-gated (16 averages without, 96 with water suppression [WS]) data acquisition as reference and navigator-free data acquisition with a fixed scan time (48 without WS, 304 with WS), cardiac-triggered point-resolved spectroscopy (PRESS).

ASSESSMENT

Navigator-free data acquisition with retrospective phase-based gating was compared with prospective navigator-gating. Navigator-free acquisition was repeated in 10 subjects to assess reproducibility. Scan time was assessed for prospective and retrospective gating. Retrospective phase-based gating was performed using a threshold based on the standard deviation (SD) of individual water (W) and triglyceride (TG) phases.

STATISTICAL TESTS

T-tests and Bland-Altman analysis.

RESULTS

The duration of the prospective navigator-gated scans ranged from 6:09 minutes to 21:50 minutes (mean 10:05 ± 3:46 min, gating efficiency 40.4 ± 10.5%), while data acquisition for retrospective phase-based gating had a fixed scan time of 11:44 minutes. Retrospective phase-based gating using a threshold of 1 × SD yielded a gating efficiency of 72.7 ± 4.3% and a coefficient of variation (CoV) of triglyceride-to-water ratios of 9.8% compared with the navigated reference. The intrasubject reproducibility of retrospective gating revealed a CoV of 9.5%.

DATA CONCLUSION

Cardiac proton MRS employing retrospective phase-based gating is feasible and provides reproducible assessment of TG/W in a fixed scan time. Since scan time is independent of respiratory motion, retrospective phase-based gating offers an approach to motion compensation with predictable exam time for proton MRS of the heart.

LEVEL OF EVIDENCE

2 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2019;50:1973-1981.

Cardiovascular magnetic resonance T2* mapping for structural alterations in hypertrophic cardiomyopathy

•

HCM patients exhibited significantly decreased T2* values compared to controls.

•

Within HCM patients, those with myocardial fibrosis presented with decreased T2* values.

•

T2* provided good diagnostic accuracy to diagnose HCM with fibrosis.

•

T2* may add information for identifying a higher risk sub-group of HCM patients.

Purpose

Hypertrophic cardiomyopathy (HCM) is characterized by a heterogeneous morphology and variable prognosis. A mismatch between left ventricular mass (LVM) and microvascular circulation with corresponding relative ischemia has been implicated to cause myocardial replacement fibrosis that deteriorates prognosis. Besides parametric T1 mapping, Cardiovascular Magnetic Resonance (CMR) T2* mapping is able to identify ischemia as well as fibrosis in cardiac and extracardiac diseases. Therefore, we aimed to investigate the value of T2* mapping to characterize structural alterations in patients with HCM.

Methods

CMR was performed on a 1.5 T MR imaging system (Achieva, Philips, Best, Netherlands) using a 5-channel coil in patients with HCM (n = 103, 50.6 ± 16.4 years) and in age- and gender-matched controls (n = 20, 44.8 ± 16.9 years). T2* mapping (1 midventricular short axis slice) was acquired in addition to late gadolinium enhancement (LGE). T2* values were compared between patients with HCM and controls as well as between HCM patients with- and without fibrosis.

Results

HCM patients showed significantly decreased T2* values compared to controls (26.2 ± 4.6 vs. 31.3 ± 4.3 ms, p < 0.001). Especially patients with myocardial fibrosis presented with decreased T2* values in comparison to those without fibrosis (25.2 ± 4.0 vs. 28.7 ± 5.3 ms, p = 0.003). A regression model including maximum wall thickness, LVM and T2* values provided good overall diagnostic accuracy of 80% to diagnose HCM with and without fibrosis.

Conclusion

In this study, parametric mapping identified lower T2* values in HCM patients compared to controls, especially in a sub-group of patients with myocardial fibrosis. As myocardial fibrosis has been suggested to influence prognosis of patients with HCM, T2* mapping may add information for identifying a higher risk sub-group of HCM patients.

Myocardial triglycerides in cardiac amyloidosis assessed by proton cardiovascular magnetic resonance spectroscopy

BACKGROUND

Cardiac involvement of amyloidosis leads to left-ventricular (LV) wall thickening with progressive heart failure requiring rehospitalization. Cardiovascular magnetic resonance (CMR) is a valuable tool to non-invasively assess myocardial thickening as well as structural changes. Proton CMR spectroscopy (1H-CMRS) additionally allows assessing metabolites including triglycerides (TG) and total creatine (CR). However, opposing results exist regarding utilization of these metabolites in LV hypertrophy or thickening. Therefore, the aim of this study was to measure metabolic alterations using 1H-CMRS in a group of patients with thickened myocardium caused by cardiac amyloidosis.

METHODS

1H-CMRS was performed on a 1.5 T system (Achieva, Philips Healthcare, Best, The Netherlands) using a 5-channel receive coil in 11 patients with cardiac amyloidosis (60.5 ± 11.4 years, 8 males) and 11 age- and gender-matched controls (63.2 ± 8.9 years, 8 males). After cardiac morphology and function assessment, proton spectra from the interventricular septum (IVS) were acquired using a double-triggered PRESS sequence. Post-processing was performed using a customized reconstruction pipeline based on ReconFrame (GyroTools LLC, Zurich, Switzerland). Spectra were fitted in jMRUI/AMARES and the ratios of triglyceride-to-water (TG/W) and total creatine-to-water (CR/W) were calculated.

RESULTS

Besides an increased LV mass and a thickened IVS concomitant to the disease characteristics, patients with cardiac amyloidosis presented with decreased global longitudinal (GLS) and circumferential (GCS) strain. LV ejection fraction was preserved relative to controls (60.0 ± 13.2 vs. 66.1 ± 4.3%, p = 0.17). Myocardial TG/W ratios were significantly decreased compared to controls (0.53 ± 0.23 vs. 0.80 ± 0.26%, p = 0.015). CR/W ratios did not show a difference between both groups, but a higher standard deviation in patients with cardiac amyloidosis was observed. Pearson correlation revealed a negative association between elevated LV mass and TG/W (R = - 0.59, p = 0.004) as well as GCS (R = - 0.48, p = 0.025).

CONCLUSIONS

A decrease in myocardial TG/W can be detected in patients with cardiac amyloidosis alongside impaired cardiac function with an association to the degree of myocardial thickening. Accordingly, 1H-CMRS may provide an additional diagnostic tool to gauge progression of cardiac amyloidosis along with standard imaging sequences.

TRIAL REGISTRATION

EK 2013-0132.

Cardiac- versus diaphragm-based respiratory navigation for proton spectroscopy of the heart

OBJECTIVES

To study inter-individual differences of the relation between diaphragm and heart motion, the objective of the present study was to implement respiratory navigation on the heart and compare it against the established method of navigator gating on the diaphragm for single-voxel cardiac ¹H-MRS.

MATERIALS AND METHODS

¹H-MRS was performed on a 1.5T system in 19 healthy volunteers of mixed age (range 24-75 years). Spectra were recorded in a 6-8 ml voxel in the ventricular septum using a PRESS (point-resolved spectroscopy) sequence and ECG gating. Water-unsuppressed data acquired with pencil beam navigation on the heart were compared to data with navigation on the diaphragm. Water-suppressed data were obtained to assess triglyceride-to-water ratios.

RESULTS

Water phase and amplitude fluctuations for cardiac versus diaphragm navigation did not reveal significant differences. Both navigator positions provided comparable triglyceride-to-water ratios and gating efficiencies (coefficient of variation (CoV) 7.0%). The cardiac navigator showed a good reproducibility (CoV 5.2%).

DISCUSSION

Respiratory navigation on the heart does not convey an advantage over diaphragm-based navigator gating for cardiac ¹H-MRS, but also no disadvantage. Consequently, cardiac and diaphragm respiratory navigation may be used interchangeably.

Funktionalität und nichtinvasive Bildgebung

Nichtinvasive Bildgebung spielt eine zentrale Rolle bei Diagnose, Risikostratifizierung und klinischem Management von Patienten mit stabiler koronarer Herzkrankheit (KHK). Die Entscheidung zu einer anatomischen oder funktionellen Bildgebung wird anhand der Patienteneignung, der Prätestwahrscheinlichkeit sowie der lokalen Methodenverfügbarkeit und Expertise getroffen. Aktuelle große Studien zeigen, dass die anatomische Bildgebung zwar die KHK diagnostiziert, aber im Vergleich zur funktionellen Bildgebung keinen signifikanten Mehrwert für die Vorhersage der Gesamtletalität hat. Neben der Funktion der koronaren Makrostrombahn können funktionale Bildgebungsmodalitäten auch die der Mikrostrombahn mit signifikant besserer Vorhersage der Gesamtletalität erfassen. Die Wertigkeit der Ischämietestung ist vor dem Hintergrund der älter werdenden Patienten mit untypischen Symptomen und damit schwieriger Berechnung der Prätestwahrscheinlichkeit als besonders hoch einzustufen. Aktuelle technische Entwicklungen aller Modalitäten erweitern in unterschiedlicher Geschwindigkeit deren Präzision und diagnostische Genauigkeit. Durch eine Vielzahl an randomisierten, kontrollierten Studien wird die klinische Bedeutung der einzelnen Bildgebungsmodalitäten in Bezug auf Kosten, Entscheidungspfade und Letalität der Patienten kontrovers diskutiert.

Abnormal T2 mapping cardiovascular magnetic resonance correlates with adverse clinical outcome in patients with suspected acute myocarditis

BACKGROUND

While most patients recover from suspected acute myocarditis (sAMC) some develop progressive disease with 5-year mortality up to 20%. Recently, parametric Cardiovascular Magnetic Resonance (CMR) approaches, quantifying native T1 and T2 relaxation time, have demonstrated the ability to increase diagnostic accuracy. However, prognostic implications of T2 values in this cohort are unknown. The purpose of the study was to investigate the prognostic relevance of elevated CMR T2 values in patients with sAMC.

METHODS AND RESULTS

We carried out a prospective study in 46 patients with sAMC defined by current ESC recommendations. A combined endpoint was defined by the occurrence of at least one major adverse cardiac event (MACE) and hospitalisation for heart failure. Event rate was 24% (n = 11) for 1-year-MACE and hospitalisation. A follow-up after 11 ± 7 months was performed in 98% of the patients. Global T2 values were significantly increased at acute stage of disease compared to controls and decreased over time. During acute disease, elevated global T2 time (odds ratio 6.3, p < 0.02) as well as myocardial fraction with T2 time >80 ms (odds ratio 4.9, p < 0.04) predicted occurrence of the combined endpoint. Patients with clinical recovery revealed significantly decreased T2 relaxation times at follow-up examinations; however, T2 values were still elevated compared to healthy controls.

CONCLUSION

Assessment of myocardial T2 relaxation times at initial presentation facilitates CMR-based risk stratification in patients with acute myocarditis. T2 Mapping may emerge as a new tool to monitor inflammatory myocardial injuries during the course of disease.

Multiparametric cardiac magnetic resonance imaging (CMR) for the diagnosis of Loeffler's endocarditis: a case report

BACKGROUND

Endocarditis parietalis fibroplastica Löfflein (EPF) is a rare form of primary restrictive cardiomyopathy with poor prognosis. It is generally caused by hypereosinophilic syndrome with eosinophilic penetration of the heart. This leads to congestive heart failure in three different stages. As a frequent manifestation of neoplastic diseases, cardiac involvement means poor prognosis.

CASE PRESENTATION

The present report deals with a case of EPF caused by non-specified T-cell lymphoma (T-NOS). Besides an elevated Troponin-T enzyme, the electrocardiogram and the transthoracic echocardiography did not show any characteristic results. Due to risk/benefit assessment and low thrombocyte amounts, endomyocardial biopsy and catheterization were discarded. Using cardiovascular magnetic resonance (CMR) with steady-state free precession sequences, T2-mappping, strain analysis and late gadolinium enhancement, we were able to clearly highlight cardiac involvement at different stages. These findings characterized T-NOS as a palliative situation.

CONCLUSION

Multiparametric CMR can not only identify EPF but also characterize the patchy disease state. This provides an individual prognosis assessment. Aside from prognosis estimation, it can also be used for therapy monitoring.

Acute chest pain in a triathlete: rupture of the noncoronary sinus of Valsalva into the right ventricle

Sinus of Valsalva (SoV) aneurysm is a rare cardiac disease which can be congenital or acquired. A ruptured SoV aneurysm presents a clinical emergency and can lead to progressively deteriorating heart failure. Therefore, appropriate treatment requires prompt and accurate diagnosis. Most ruptured or nonruptured SoV aneurysms are diagnosed by the means of echocardiography. However, cardiovascular magnetic resonance (CMR) can provide information on precise anatomy and mechanisms due to its excellent soft tissue contrast and high resolution, and thereby allows for optimized preoperative planning of the repair strategy. In the present case, we demonstrate the benefit of CMR in emergency settings.

Depicting the inner and outer nose: the representation of the nose and the nasal mucosa on the human primary somatosensory cortex (SI)

The nose is important not only for breathing, filtering air, and perceiving olfactory stimuli. Although the face and hands have been mapped, the representation of the internal and external surface of the nose on the primary somatosensory cortex (SI) is still poorly understood. To fill this gap functional magnetic resonance imaging (fMRI) was used to localize the nose and the nasal mucosa in the Brodman areas (BAs) 3b, 1, and 2 of the human postcentral gyrus (PG). Tactile stimulation during fMRI was applied via a customized pneumatically driven device to six stimulation sites: the alar wing of the nose, the lateral nasal mucosa, and the hand (serving as a reference area) on the left and right side of the body. Individual representations could be discriminated for the left and right hand, for the left nasal mucosa and left alar wing of the nose in BA 3b and BA 1 by comparing mean activation maxima and Euclidean distances. Right-sided nasal conditions and conditions in BA 2 could further be separated by different Euclidean distances. Regarding the alar wing of the nose, the results concurred with the classic sensory homunculus proposed by Penfield and colleagues. The nasal mucosa was not only determined an individual and bilateral representation, its position on the somatosensory cortex is also situated closer to the caudal end of the PG compared to that of the alar wing of the nose and the hand. As SI is commonly activated during the perception of odors, these findings underscore the importance of the knowledge of the representation of the nasal mucosa on the primary somatosensory cortex, especially for interpretation of results of functional imaging studies about the sense of smell.