Mirja Neizel-Wittke

Myocardial T2 mapping reveals age- and sex-related differences in volunteers

BackgroundT2 mapping indicates to be a sensitive method for detection of tissue oedema hidden beyond the detection limits of T2-weighted Cardiovascular Magnetic Resonance (CMR). However, due to variability of baseline T2 values in volunteers, reference values need to be defined. Therefore, the aim of the study was to investigate the effects of age and sex on quantitative T2 mapping with a turbo gradient-spin-echo (GRASE) sequence at 1.5 T. For that reason, we studied sensitivity issues as well as technical and biological effects on GRASE-derived myocardial T2 maps. Furthermore, intra- and interobserver variability were calculated using data from a large volunteer group.MethodsGRASE-derived multiecho images were analysed using dedicated software. After sequence optimization, validation and sensitivity measurements were performed in muscle phantoms ex vivo and in vivo. The optimized parameters were used to analyse CMR images of 74 volunteers of mixed sex and a wide range of age with typical prevalence of hypertension and diabetes. Myocardial T2 values were analysed globally and according to the 17 segment model. Strain-encoded (SENC) imaging was additionally performed to investigate possible effects of myocardial strain on global or segmental T2 values.ResultsEx vivo studies in muscle phantoms showed, that GRASE-derived T2 values were comparable to those acquired by a standard multiecho spinecho sequence but faster by a factor of 6. Besides that, T2 values reflected tissue water content. The in vivo measurements in volunteers revealed intra- and interobserver correlations with R2=0.91 and R2=0.94 as well as a coefficients of variation of 2.4% and 2.2%, respectively. While global T2 time significantly decreased towards the heart basis, female volunteers had significant higher T2 time irrespective of myocardial region. We found no correlation of segmental T2 values with maximal systolic, diastolic strain or heart rate. Interestingly, volunteers´ age was significantly correlated to T2 time while that was not the case for other coincident cardiovascular risk factors.ConclusionGRASE-derived T2 maps are highly reproducible. However, female sex and aging with typical prevalence of hypertension and diabetes were accompanied by increased myocardial T2 values. Thus, sex and age must be considered as influence factors when using GRASE in a diagnostic manner.

Myocardial T2 Mapping Increases Noninvasive Diagnostic Accuracy for Biopsy-Proven Myocarditis

Detection of myocardial inflammation in patients with clinically suspected acute myocarditis (sAMC) is of prognostic importance but remains a challenge in routine clinical practice [(1)][1]. Compared with endomyocardial biopsy (EMB), the diagnostic gold standard, cardiovascular magnetic resonance (

T2-Mapping CMR increases the diagnostic sensitivity for detection of myocardial inflammation in patients with possible myocarditis - a prospective endomyocardial biopsy-controlled study

Myocarditis has been reported in up to 20% of sudden cardiac death in young adults and is a frequent precursor of dilated cardiomyopathy. Unfortunately, the diagnostic tools for detection of myocarditis are still imperfect: Sensitivity of endomyocardial biopsy (EMB) is reduced largely due to the inherent sampling error. Cardiac magnetic resonance (CMR) offers the advantage of analysing the whole myocardium, but contrast-enhanced as well as T2weighted CMR exhibit inadequate sensitivity, especially during early stages of inflammation. Our hypothesis was that quantitative T2 relaxation mapping increases diagnostic sensitivity in CMR-based diagnosis of myocarditis. Methods We carried out a prospective observational study in patients with probable acute myocarditis characterized by clinical presentation, new global or regional wall abnormalities or arrhythmias or hsTNT-elevation. Of the 55 patients screened, two patients did not undergo CMR (1 pacemaker, 1 ECLS-support) and 16 patients refused EMB. The remaining 37 patients underwent EMB and CMR examination (1.5 T, Archieva, Philips) within 36h. Histological evaluation was performed by two independent pathologists (hematoxylin eosin staining, picrosirius red, IH CD68, CD45R0 and CD3) and by molecular analysis for viral replication/genome. CMR data were analysed blinded with respect to ventricular volumes and ejection fraction as well as T2, LGE and Strain Encoded (SENC)Imaging. A GRASE sequence (15 Echoes separated by 10ms, res: 2x2x10 mm2, 3 short axis slices) was used for localized T2 mapping. Age-matched volunteers (37) served as controls for ROC curve analysis in terms of quantitative T2-mapping. Results were compared by two-sided t-Test; p<0.05 was considered significant. Results

MR-guided renal denervation: first experience in pigs

Background Renal nerve ablation under fluoroscopy has emerged as a promising therapy in patients non-responding to oral anti-hypertensive medications. However, a considerable drawback of this technique is the lack of exact and immediate therapy control. CMR has the advantage of simultaneously combining functional imaging, anatomic and intraprocedural guidance in one examination without radiation and ionidied contrast agents.

CMR-guidance of passively tracked endomyocardial biopsy in an in vivo porcine model

Endomyocardial biopsy (EMB) is considered to be the diagnostic gold-standard in detection of myocardial-inflammation. EMB is usually conducted under fluoroscopy without any specific target information. Specific target-information provided by cardiovascular magnetic resonance (CMR) may improve specificity of EMB. The aim was to investigate feasibility and safety of CMR-guided and targeted EMB in a preclinical-model using passively-tracked devices. Procedures were performed on a MRI-System equipped with an Interventional Software-Platform for real-time imaging. Ex vivo experiments were conducted to optimize visibility of the guide-sheath. In vivo experiments were conducted in 2 pigs for technical feasibility assessment and in 4 pigs after acute myocardial infarction to test feasibility of guided and lesion targeted EMB. For anatomical real-time imaging a single-shot-balanced-SSFP-sequence was applied. Myocardial targets were identified under real-time imaging (single-shot-T2 (sshT2) and single-shot Late-Gadolinium-Enhancement (sshLGE) sequences). Ex vivo experiments demonstrated best visibility of continuously labelled guide-sheath. CMR-guided EMB was feasible in all cases without major complications. Likewise, lesion-targeting endomyocardial biopsy was feasible in two cases. Biopsies exhibited appropriate sizes and qualities. Real-time lesion sequences revealed comparable CNR values to clinical-protocols. Real-time imaging of lesions showed following signal- and contrast-to-noise ratios (SNR/CNR): SNR of sshT2- and sshLGE was 124 ± 35 and 67 ± 51 respectively, whereas CNR was 81 ± 30 and 57 ± 44. This study demonstrates feasibility and safety of CMR-guided and basically targeted EMB with passively-tracked devices. Signal-to-noise ratios of real-time sequences is non-inferior to standard sequences for lesion detection. CMR-guidance may improve diagnostic accuracy of EMB since CMR can detect myocardial-targets under real-time-imaging.

Acute regadenoson stress prefusion testing using cardiac MRI is a valuable test of high predictive value for risk stratification of COPD-patients with NSTEM

Background The diagnostic dilemma of patients suffering from chronic obstructive pulmonary disease (COPD) presenting with symptoms equivalent to an acute coronary syndrome (ACS) and slightly elevated high sensitive troponine in the observational range (hsTnT 14-53 ng/l) is complex. Prognostic impact of elevated hsTnT demand further investigation. Comorbidities of COPD and coronary artery disease are frequent, risk factors congruent. The acute setting demands a safe and easily conductible test to identify coronary problems reliably. Echocardiographic imaging quality is often low due to emphysema. Adenosine is contraindicated due to its bronchospasmic effect. The new vasodilatator regadenoson does not bear this limitation. This study aims to evaluate feasibility and prognostic power of regadenoson stress cMRI in the above described population.

Role of myocardial scar on 30day outcome after TAVI

Background Transcatheter aortic valve implantation (TAVI) offers a minimal invasive option for treatment of patients with severe aortic stenosis at high risk for conventional surgery. The objective of this study was to investigate whether presence of late gadolinium enhancement (LGE) patterns detected by cardiac magnetic resonance imaging (cMRI) is a risk factor for major adverse cardiac events (MACE) after TAVI within the first 30 days.

Feasibility and results of acute cardiac stress MRI with regadenoson for risk stratification of COPD-patients with NSTEMI

Background Patients with chronic obstructive pulmonary disease (COPD) often present with symptoms equivalent to an acute coronary syndrome (ACS) and slightly elevated high sensitive troponine in the observational range (hsTnT 14-53 ng/l). While this cannot differentiate between coronary or pulmonary origin of myocardial damage it necessitates further investigation since it has prognostic impact. Comorbidity of COPD and coronary heart disease is frequent and risk factors are also congruent. In this acute setting, a safe, and reliable test to identify coronary problems is of great value. Non-invasive assessment of these patients is hampered by low echocardiographic imaging quality due to pulmonary emphysema and by the bronchospasmic effect of adenosine. With the new vasodilatator regadenoson, stress-MRI is possible in patients with COPD. The aim of this study was to evaluate the value of regadenoson stress MRI in patients with known COPD and low troponine values.

Detection of myocardial scar using T2* in a clinical setting

Background Detection of late gadolinium enhancement (LGE) is the method of choice for imaging myocardial scar. However, patients who suffer from cardiovascular disease often are afflicted with renal impairment. As a GFR <30 ml/min bears the risk of nephrogenic systemic fibrosis it would be beneficial to develop alternative cardiac imaging methods without contrast agent. De Jong et al have already used UTE (ultra short echo time) to detect myocardial scar with a fast T2* signal decay in a rat infarct model. The aim of the study was to validate UTE imaging to detect myocardial scar without contrast agent in patients with coronary artery disease.