Andre Rudolph

Noninvasive Detection of Fibrosis Applying Contrast-Enhanced Cardiac Magnetic Resonance in Different Forms of Left Ventricular Hypertrophy: Relation to Remodeling

OBJECTIVES We aimed to evaluate the incidence and patterns of late gadolinium enhancement (LGE) in different forms of left ventricular hypertrophy (LVH) and to determine their relation to severity of left ventricular (LV) remodeling. BACKGROUND Left ventricular hypertrophy is an independent predictor of cardiac mortality. The relationship between LVH and myocardial fibrosis as defined by LGE cardiovascular magnetic resonance (CMR) is not well understood. METHODS A total of 440 patients with aortic stenosis (AS), arterial hypertension (AH), or hypertrophic cardiomyopathy (HCM) fulfilling echo criteria of LVH underwent CMR with assessment of LV size, weight, function, and LGE. Patients with increased left ventricular mass index (LVMI) resulting in global LVH in CMR were included in the study. RESULTS Criteria were fulfilled by 83 patients (56 men, age 57 +/- 14 years; AS, n = 21; AH, n = 26; HCM, n = 36). Late gadolinium enhancement was present in all forms of LVH (AS: 62%, AH: 50%; HCM: 72%, p = NS) and was correlated with LVMI (r = 0.237, p = 0.045). There was no significant relationship between morphological obstruction and LGE. The AS subjects with LGE showed higher LV end-diastolic volumes than those without (1.0 +/- 0.2 ml/cm vs. 0.8 +/- 0.2 ml/cm, p < 0.015). Typical patterns of LGE were observed in HCM but not in AS and AH. CONCLUSIONS Fibrosis as detected by CMR is a frequent feature of LVH, regardless of its cause, and depends on the severity of LV remodeling. As LGE emerges as a useful tool for risk stratification also in nonischemic heart diseases, our findings have the potential to individualize treatment strategies.

Cardiac magnetic resonance monitors reversible and irreversible myocardial injury in myocarditis

OBJECTIVES We sought to assess the value of cardiac magnetic resonance (CMR) to monitor the spectrum of myocarditis-related injuries over the course of the disease. BACKGROUND Myocarditis is associated with a wide range of myocardial tissue injuries, both reversible and irreversible. Differentiating these types of injuries is a clinical demand. METHODS We studied 36 patients (31 males, age 33 +/- 14 years) hospitalized with myocarditis during the acute phase and 18 +/- 10 months thereafter. CMR was performed on 2 1.5T scanners and included the following techniques: steady-state free precession (to assess left ventricular function and volumes), T2-weighted (myocardial edema), early (global relative enhancement [gRE], reflecting increased capillary leakage) and late T1-weighted after gadolinium-DTPA injection (late gadolinium enhancement [LGE], reflecting irreversible injury). RESULTS In the acute phase, T2 ratio was elevated in 86%, gRE in 80%, and LGE was present in 63%. At follow-up, ejection fraction increased from 56 +/- 8% to 62 +/- 7% (p < 0.0001) while both T2 ratio (2.4 +/- 0.5 to 1.9 +/- 0.2; p < 0.0001) and gRE (7.6 +/- 8 to 4.4 +/- 4; p = 0.018) significantly decreased. LGE persisted in all but 1 patient in whom LGE completely resolved. No patient had simultaneous elevation of T2 and gRE during the convalescent phase, resulting in a negative predictive value of 100% to differentiate the 2 phases of the disease. The acute phase T2 ratio correlated significantly with the change of end-diastolic volume over time (beta = 0.47; p = 0.008). This relation remained significant in a stepwise regression analysis model including T2 ratio, gRE, LGE extent, baseline ejection fraction, age, and creatine kinase, in which only T2 emerged as an independent predictor of the change in end-diastolic volume. CONCLUSIONS A comprehensive CMR approach is a useful tool to monitor the reversible and irreversible myocardial tissue injuries over the course of myocarditis and to differentiate acute from healed myocarditis in patients with still-preserved ejection fraction.

An open-source software tool for the generation of relaxation time maps in magnetic resonance imaging

BackgroundIn magnetic resonance (MR) imaging, T1, T2 and T2* relaxation times represent characteristic tissue properties that can be quantified with the help of specific imaging strategies. While there are basic software tools for specific pulse sequences, until now there is no universal software program available to automate pixel-wise mapping of relaxation times from various types of images or MR systems. Such a software program would allow researchers to test and compare new imaging strategies and thus would significantly facilitate research in the area of quantitative tissue characterization.ResultsAfter defining requirements for a universal MR mapping tool, a software program named MRmap was created using a high-level graphics language. Additional features include a manual registration tool for source images with motion artifacts and a tabular DICOM viewer to examine pulse sequence parameters. MRmap was successfully tested on three different computer platforms with image data from three different MR system manufacturers and five different sorts of pulse sequences: multi-image inversion recovery T1; Look-Locker/TOMROP T1; modified Look-Locker (MOLLI) T1; single-echo T2/T2*; and multi-echo T2/T2*. Computing times varied between 2 and 113 seconds. Estimates of relaxation times compared favorably to those obtained from non-automated curve fitting. Completed maps were exported in DICOM format and could be read in standard software packages used for analysis of clinical and research MR data.ConclusionsMRmap is a flexible cross-platform research tool that enables accurate mapping of relaxation times from various pulse sequences. The software allows researchers to optimize quantitative MR strategies in a manufacturer-independent fashion. The program and its source code were made available as open-source software on the internet.

Feasibility of cardiovascular magnetic resonance to assess the orifice area of aortic bioprostheses.

Background—Prosthetic orifice area, usually calculated by transthoracic echocardiography (TTE) or transesophageal echocardiography (TEE), provides important information regarding the hemodynamic performance of aortic bioprostheses. However, both TTE and TEE have limitations; therefore accurate and reproducible determination of the orifice area often remains a challenge. The present study aimed to investigate the feasibility of cardiovascular magnetic resonance (CMR) to assess the orifice areas of aortic bioprostheses. Methods and Results—CMR planimetry of the orifice area was performed in 65 patients (43/22 stented/stentless prostheses; mean time since implantation, 3.1±2.8 years; mean orifice area [TTE], 1.70±0.43 cm2; 62 normally functioning prostheses, 2 severe stenoses, and 1 severe regurgitation) in an imaging plane perpendicular to the transprosthetic flow using steady-state free-precession cine imaging under breath-hold conditions on a 1.5-T MR system. CMR results were compared with TTE (continuity equation, n=65) and TEE (planimetry, n=31). CMR planimetry was readily feasible in 80.0%; feasible with limitation in 15.4% because of stent, flow, and sternal wire artifacts; and impossible in 4.6% because of flow artifacts. Correlations of the orifice areas by CMR with TTE (r=0.82) and CMR with TEE (r=0.92) were significant. The average difference between the methods was −0.02±0.24 cm2 (TTE) and 0.05±0.15 cm2 (TEE). Agreement was present for stented and stentless devices and independent of orifice size. Intraobserver and interobserver variabilities of CMR planimetry were 6.7±5.4% and 11.5±7.8%. Conclusions—The assessment of aortic bioprostheses with normal orifice areas by CMR is technically feasible and provides orifice areas with a close correlation to echocardiography and low observer dependency.

Gender-specific differences in left ventricular remodelling and fibrosis in hypertrophic cardiomyopathy: insights from cardiovascular magnetic resonance.

Gender is an independent risk factor for heart failure mortality in hypertrophic cardiomyopathy (HCM).

Assessment of mitral bioprostheses using cardiovascular magnetic resonance

BackgroundThe orifice area of mitral bioprostheses provides important information regarding their hemodynamic performance. It is usually calculated by transthoracic echocardiography (TTE), however, accurate and reproducible determination may be challenging. Cardiovascular magnetic resonance (CMR) has been proven as an accurate alternative for assessing aortic bioprostheses. However, whether CMR can be similarly applied for bioprostheses in the mitral position, particularly in the presence of frequently coincident arrhythmias, is unclear. The aim of the study is to test the feasibility of CMR to evaluate the orifice area of mitral bioprostheses.MethodsCMR planimetry was performed in 18 consecutive patients with mitral bioprostheses (n = 13 Hancock®, n = 4 Labcore®, n = 1 Perimount®; mean time since implantation 4.5 ± 3.9 years) in an imaging plane perpendicular to the transprosthetic flow using steady-state free-precession cine imaging under breath-hold conditions on a 1.5T MR system. CMR results were compared with pressure half-time derived orifice areas obtained by TTE.ResultsSix subjects were in sinus rhythm, 11 in atrial fibrillation, and 1 exhibited frequent ventricular extrasystoles. CMR image quality was rated as good in 10, moderate in 6, and significantly impaired in 2 subjects. In one prosthetic type (Perimount®), strong stent artifacts occurred. Orifice areas by CMR (mean 2.1 ± 0.3 cm2) and TTE (mean 2.1 ± 0.3 cm2) correlated significantly (r = 0.94; p < 0.001). Bland-Altman analysis showed a 95% confidence interval from -0.16 to 0.28 cm2 (mean difference 0.06 ± 0.11 cm2; range -0.1 to 0.3 cm2). Intra- and inter-observer variabilities of CMR planimetry were 4.5 ± 2.9% and 7.9 ± 5.2%.ConclusionsThe assessment of mitral bioprostheses using CMR is feasible even in those with arrhythmias, providing orifice areas with close agreement to echocardiography and low observer dependency. Larger samples with a greater variety of prosthetic types and more cases of prosthetic dysfunction are required to confirm these preliminary results.

Heritability of left ventricular and papillary muscle heart size: a twin study with cardiac magnetic resonance imaging

AIMS Earlier studies in monozygotic (MZ) and dizygotic (DZ) twins showed genetic variance on echocardiographically determined heart size. However, cardiovascular magnetic resonance (CMR) is more precise and reproducible. We performed a twin study relying on CMR, focusing on left ventricular (LV) mass and papillary muscle, since there are no genetic reports on this structure. METHODS AND RESULTS We measured left heart dimensions of 25 healthy twin pairs with a 1.5T MR scanner, analysed with the mass, Medis Software. We performed heritability analysis and tests for genetic influences shared between cardiac structures. We found that CMR-based heritability estimates (h(2) = 84%) substantially exceeded estimates based on echocardiography. We also found significant genetic influence on papillary muscle mass (h(2) = 82%). Bivariate analysis of papillary and LV muscle mass revealed significant genetic influences shared by both phenotypes (genetic correlation 0.59) and suggested an additional genetic component specific to papillary muscle. We observed correlations between body mass index, surface area, and systolic blood pressure with cardiac dimensions, even in this small study. Environmental influences were relevant as well, indicating reciprocal influences on papillary vs. LV muscle mass. CONCLUSION Cardiovascular magnetic resonance, even with few subjects, allows a genetic assessment of cardiac structures that cannot be attained with echocardiography. Hitherto fore unappreciated relationships can be uncovered by this method.

Detection and monitoring of acute myocarditis applying quantitative cardiovascular magnetic resonance

Background— Cardiovascular magnetic resonance based on the Lake Louise Criteria is used to make the diagnosis of acute myocarditis. Novel quantitative parametric mapping techniques promise to overcome some of its limitations. We aimed to evaluate quantitative cardiovascular magnetic resonance to detect and monitor acute myocarditis. Methods and Results— Eighteen patients with clinical diagnosis of acute myocarditis (25 years [23–38 years]; 78% males) were prospectively enrolled and repeatedly underwent cardiovascular magnetic resonance at 1.5 T seven days (5–10 days) after symptom onset (FU0), after 5 weeks (FU1), and after 6 months (FU2). Eighteen age- and sex-matched healthy subjects served as controls. Cardiovascular magnetic resonance included imaging of edema, hyperemia, necrosis, and fibrosis using semiquantitative T2-weighted spin echo, T2 mapping, and T1 mapping before and 3 and 10 minutes after gadobutrol administration. Extracellular volume for diffuse and late gadolinium enhancement for focal fibrosis were assessed. Compared with controls, patients had significantly higher global T2 times at FU0 (55.1 ms [53.3–57.2 ms] versus 50.2 ms [49.2–52.0 ms]; P<0.001) and at FU1 (52.0 ms [52.0–53.2 ms]; P=0.007), which normalized at FU2 (50.9 ms [49.6–53.3 ms]; P=0.323). Global native T1 times in patients were elevated acutely (1004 ms [988–1048 ms] versus 975 ms [957–1004 ms]; P=0.002) and remained elevated throughout the follow-up (FU1: 998 ms [990–1027 ms]; P=0.014; FU2: 1000 ms [972–1027 ms]; P=0.044). Global extracellular volume fraction was statistically not different between patients and controls (P=0.057). 77.8% (14/18) of patients had focal late gadolinium enhancement. T2 ratio was significantly elevated in patients with myocarditis at FU0 (2.2 [2.0–2.3] versus 1.6 [1.5–1.7]; P<0.001). The difference decreased during follow-up (FU1: 1.9 [1.7–1.9]; P=0.001 and FU2: 1.7 [1.7–1.8]; P=0.053). The diagnostic accuracy to discriminate between patients with acute myocarditis and healthy controls was 86% for T2>52 ms, 78% for native T1>981 ms, 74% for extracellular volume fraction >0.24, and 100% for T2 ratio >1.9. Conclusions— Although both T2 and T1 mapping reliably detected acute myocarditis, only T2 mapping discriminated between acute and healed stages, underlining the incremental value of T2 mapping.

Differentiation of acute and chronic myocardial infarction using T2-weighted imaging, late enhancement and T1 and T2 mapping - a pilot study at 3T

Background Qualitative assessment of myocardial T2-weighted and late enhancement (LGE) images has been demonstrated to differentiate acute from chronic myocardial infarction (AMI, CMI). Parametric mapping could help to overcome challenges in image quality and could contribute to making contrast media application obsolete. The aim of this pilot study was to analyze, whether T2and T1maps are useful to discriminate AMI from CMI.

Equivalence of conventional and fast late gadolinium enhancement (LGE) techniques for quantitative evaluation of fibrosis in ischemic and non-ischemic cardiac disease - Save the Time!

Methods Patients with myocardial infarction (n = 45), myocarditis (n = 25) or hypertrophic cardiomyopathy (HCM) (n = 15) were prospectively enrolled. After administration of gadolinium contrast agent, LGE images were acquired ECG-gated in short axis slices (slice thickness 7 mm, no gap) using 4 different LGE sequences: (1) conventional segmented 2D phase-sensitive inversion recovery in single-slice/single-breath-hold technique (2D-PSIR; gold standard; TR 744 ms, TE 5,17 ms, voxel size 1.4 × 1.4 × 7.0 mm), (2) single-breath-hold 3D-IR sequence (3D-IR bh; TR 924 ms, TE 1.06 ms, voxel size 1.9 × 1.9 × 7.0 mm), (3) single breath-hold 3D-SSFP sequence (3DSSFP; TE 700 ms, TE 1.05 ms, voxel size 1.9 × 1.9 × 7.0 mm) and (4) non-breath-hold technique (3D-IR nbh). (Figure 1) For all techniques, inversion time was individually adjusted to null the remote myocardium. Myocardial fibrosis was quantitatively assessed using a semiautomated threshold method; positive LGE was defined as signal intensity 6 standard deviations (SD) above signal intensity of remote myocardium for myocardial infarction and 3 SD for myocarditis / HCM. Detection rates were determined as number of matching myocardial AHA segments with detected LGE in gold standard and each fast technique.