Matthias G. Friedrich

Contrast Media–Enhanced Magnetic Resonance Imaging Visualizes Myocardial Changes in the Course of Viral Myocarditis

BACKGROUND The course of tissue changes in acute myocarditis in humans is not well understood. Diagnostic tools currently available are unsatisfactory. We tested the hypothesis that inflammation is reflected by signal changes in contrast-enhanced magnetic resonance imaging (MRI). METHODS AND RESULTS We assessed 44 consecutive patients with symptoms of acute myocarditis. Nineteen patients met the inclusion criteria revealing ECG changes, reduced myocardial function, elevated creatine kinase, positive troponin T, serological evidence for acute viral infection, exclusion of coronary heart disease, and positive antimyosin scintigraphy. We studied these patients on days 2, 7, 14, 28, and 84 after the onset of symptoms. We obtained ECG-triggered, T1-weighted images before and after application of 0.1 mmol/kg gadolinium. We measured the global relative signal enhancement of the left ventricular myocardium related to skeletal muscle and compared it with measurements in 18 volunteers. The global relative enhancement was higher in patients on days 2 (4.8+/-0.3 [mean+/-SE] versus 2.5+/-0.2; P<.0001); 7 (4.7+/-0.5, P<.0001); 14 (4.6+/-0.5, P<.0002); and 28 (3.9+/-0.4, P=.009) but not on day 84 (3.1+/-0.3; P=NS). On day 2, the enhancement was focal, whereas at later time points, the enhancement was diffuse. In patients with evidence of ongoing disease, the values remained elevated. CONCLUSIONS Acute myocarditis evolves from a focal to a disseminated process during the first 2 weeks after onset of symptoms. Contrast media-enhanced MRI visualizes the localization, activity, and extent of inflammation and may serve as a powerful noninvasive diagnostic tool in acute myocarditis.

Delayed Enhancement and T2-Weighted Cardiovascular Magnetic Resonance Imaging Differentiate Acute From Chronic Myocardial Infarction

Background—Delayed enhancement (DE) cardiovascular magnetic resonance (CMR) detects acute and chronic myocardial infarction (MI) by visualizing contrast media accumulation in infarcted segments. T2-weighted CMR depicts infarct-related myocardial edema as a marker of acute but not chronic myocardial injury. We investigated the clinical utility of an approach combining both techniques to differentiate acute from chronic MI. Methods and Results—Seventy-three MI patients were studied in 2 groups. Group A consisted of 15 acute MI patients who were studied twice, on day 1 and 3 months after MI. In group B, 58 patients with acute or chronic MI underwent 1 CMR scan. T2-weighted and DE images of matched slices were acquired on a 1.5-T system. In group A, quantitative segmental and region of interest–based analyses were performed to observe signal changes between the acute and chronic phases. In group B, T2-weighted and DE images were examined visually by 2 blinded observers for the presence or absence of hyperintense areas in corresponding segments. For infarct localization, coronary angiography and/or ECG changes served as the reference standard. In group A, the contrast-to-noise ratio on T2-weighted images dropped in the infarcted segments from 2.7±1.1 on day 1 to 0.1±1.2 after 3 months (P <0.0001). There was no significant change in contrast-to-noise ratio in DE images (1.9±1.5 versus 1.3±1.0; P =NS). The qualitative assessment of T2-weighted and DE images in group B yielded a specificity of 96% to differentiate acute from chronic lesions. Conclusions—An imaging approach combining DE and T2-weighted CMR accurately differentiates acute from chronic MI.

ACCF/ACR/AHA/NASCI/SCMR 2010 Expert Consensus Document on Cardiovascular Magnetic Resonance A Report of the American College of Cardiology Foundation Task Force on Expert Consensus Documents

Robert A. Harrington, MD, FACC, FAHA, Chair Jeffrey L. Anderson, MD, FACC, FAHA[††][1] Eric R. Bates, MD, FACC Charles R. Bridges, MD, MPH, FACC, FAHA Mark J. Eisenberg, MD, MPH, FACC, FAHA Victor A. Ferrari, MD, FACC, FAHA Cindy L. Grines, MD, FACC[††][1] Mark A. Hlatky, MD, FACC,

Randomised, double-blind, placebo-controlled trial of human recombinant growth hormone in patients with chronic heart failure due to dilated cardiomyopathy

BACKGROUND Some studies have suggested that treatment with recombinant human growth hormone (rhGH) increases left-ventricular mass and improves haemodynamic and functional status in patients with heart failure due to dilated cardiomyopathy. We did a double-blind, randomised, placebo-controlled study of rhGH in patients with chronic heart failure due to dilated cardiomyopathy. METHODS 50 patients (43 men) were randomly allocated treatment with subcutaneous rhGH (2 IU daily) or placebo for a minimum of 12 weeks. The primary endpoints were the effects on left-ventricular mass and systolic wall stress. The secondary endpoints were the effects on left-ventricular size and function. Data were analysed by intention to treat. FINDINGS Patients in the rhGH group had an increase in left-ventricular mass compared with those in the placebo group (27%, p=0.0001). There was no significant difference in left-ventricular systolic wall stress, mean blood pressure, or systemic vascular resistance between the two groups. New York Heart Association functional class, left-ventricular ejection fraction, and distance on the 6 min walking test were unchanged. The change in serum insulin-like growth factor (IGF)-I concentrations (rhGH 77 ng/mL; placebo -19 ng/mL, GH vs placebo p=0.0001) was significantly related to the change in left-ventricular mass (r=0.55, p=0.0001). One patient in the rhGH group was withdrawn at 6 weeks because of worsening heart failure. INTERPRETATION There is a significant increase in left-ventricular mass in patients with dilated cardiomyopathy given rhGH but this is not accompanied by an improvement in clinical status. Changes in left-ventricular mass are related to changes in serum IGF-I concentrations. Whether a longer treatment period would provide clinical benefits and decrease mortality is unknown.

T2-weighted cardiovascular magnetic resonance imaging.

Technical advances in T2‐weighted cardiovascular MR (CMR) imaging allow for accurate identification and quantification of tissue injuries that alter myocardial T2 relaxation. Of these, myocardial edema is of special relevance. Increased myocardial water content is an important feature of ischemic as well as nonischemic cardiomyopathies, which are often associated with acute myocardial inflammation. In this article, we review technical considerations and discuss clinical indications of myocardial T2‐weighted imaging. J. Magn. Reson. Imaging 2007;26:452–459.

Detection of Acutely Impaired Microvascular Reperfusion After Infarct Angioplasty With Magnetic Resonance Imaging

Background—Despite the reopening of the infarct-related artery (IRA) with infarct angioplasty, complete microvascular reperfusion does not always ensue. Methods and Results—We performed cardiovascular MRI (CMR) in 20 acute myocardial infarction (AMI) patients within 24 hours of successful infarct angioplasty and 10 control patients without obstructive coronary artery disease on a clinical 1.5-T CMR scanner. Three-month follow-up CMR in AMI patients evaluated the impact of abnormal reperfusion on recovery of function. Infarction was localized by delayed contrast hyperenhancement and impaired systolic thickening. Microvascular perfusion was assessed at rest by first-pass perfusion CMR after a bolus of gadolinium-DTPA by use of the time to 50% maximum myocardial enhancement. Whereas contrast wash-in was homogeneous in control patients, AMI patients exhibited delays in the hypokinetic region subtended by the IRA compared with remote segments in 19 of 20 patients, with a mean contrast delay of 0.9±0.1 seconds (95% CI, 0.6 to 1.2 seconds). At follow-up, the mean recovery of systolic thickening was lower in segments with a contrast delay of 2 seconds or more (10±7% versus 39±4%, P =0.001). A contrast delay ≥2 seconds and infarction >75% transmurally were independent predictors of impaired left ventricular systolic thickening at 3 months (P =0.002 for severe contrast delay, P =0.048 for >75% for transmural infarction). Conclusions—CMR detects impaired microvascular reperfusion in AMI patients despite successful infarct angioplasty, which when severe is associated with a lack of recovery of wall motion.

T1 Mapping in Patients with Acute Myocardial Infarction

Pixel-by-pixel calculation of T1 values (T1 mapping) has been used in different tissues to focus on T1 changes in a quantitative fashion. The aim of this study was to establish T1 mapping of human myocardium on a 1.5 Tesla system and to examine its diagnostic potential in patients with acute myocardial infarction (AMI). 8 patients with reperfused AMI (day 3 +/- 1) underwent multi-breath-hold MRI in a 1.5 Tesla system. Sets of five images with varying T1 weighting were acquired prior to and after the administration of contrast agent to generate images from calculated T1 values (T1 mapping). Prior to the contrast agent administration, all patients showed T1 prolongation in the area of infarction, which was identified in separate measurements using the delayed enhancement approach. Compared to noninfarcted areas, T1 values in the infarcted areas were increased by 18 +/- 7% (SE, p < 0.05). The spatial extent of the area of T1 prolongation was larger than that of the hyper-enhanced areas in conventional contrast-enhanced images. T1 maps obtained after the application of Gadolinium-DTPA revealed a T1 reduction of 27 +/- 4% in infarcted tissue compared to noninfarcted areas (p < 0.05). The areas showing T1 reduction were in agreement with the hyper-enhanced regions in conventional T1-weighted images. T1 mapping visualizes changes in the longitudinal relaxation time induced by AMI. T1 mapping can detect myocardial necrosis without the use of contrast media. Information that can be extracted from a combination of pre- and postcontrast T1 maps exceeds that from conventional contrast studies.

Cardiovascular magnetic resonance of acute myocardial infarction at a very early stage.

OBJECTIVES Very early changes in myocardial tissue composition during acute myocardial infarction (AMI) are difficult to assess in vivo. Cardiovascular magnetic resonance (CMR) imaging provides techniques for visualizing tissue pathology. BACKGROUND The diagnostic role of CMR in very acute stages of myocardial infarction is uncertain. We investigated signal intensity changes beginning within 60 min after acute coronary occlusion in patients undergoing therapeutic septal artery embolization. METHODS We investigated eight patients with hypertrophic obstructive cardiomyopathy undergoing interventional septal artery embolization by applying microparticles to reduce left ventricular outflow tract obstruction. In a clinical 1.5-tesla (T) CMR system, we visualized infarct-related myocardial signal by T(1)-weighted sequences before and 20 min after administration of contrast media (delayed enhancement) and edema-related signal by T(2)-weighted spin-echo sequences before and 58 +/- 14 min after the intervention as well as on days 1, 3, 7, 14, 28, 90, and 180 during follow-up. RESULTS Infarct-related changes as defined by contrast enhancement were observed as early as 1 h after the intervention and during six months of follow-up. In contrast, infarct-related myocardial edema, as visualized by high signal intensity in T(2)-weighted spin-echo sequences, was not consistently detectable 1 h after acute arterial occlusion; this was possible in all subsequent studies until day 28. CONCLUSIONS Contrast-enhanced magnetic resonance imaging detected infarct-related signal changes as early as 1 h after AMI in humans, whereas the sensitivity of edema-related signal changes was not sufficient during this very early stage.

Blood Oxygen Level–Dependent Magnetic Resonance Imaging in Patients with Stress-Induced Angina

Background—Blood oxygen level–dependent (BOLD) MRI reflects tissue oxygenation and may be useful for the detection of myocardial ischemia in patients with suspected coronary artery disease. Methods and Results—We studied 25 patients with stress-induced angina using a T2*-sensitive echo planar imaging sequence before and during adenosine in a single-slice approach. BOLD-MRI results were compared with quantitative angiography and adenosine thallium single-photon emission computed tomography (SPECT). Although image quality was variable because of artifacts, no data were excluded from the analysis. During adenosine, a mean signal intensity decrease was observed for myocardial segments related to coronary stenoses >75%. On average, a nonsignificant increase was observed in the other segments. The angiographically determined stenosis was correlated with BOLD-MRI results. Including all segments and using BOLD-MRI signal intensity increase cutoff value of 1.2%, BOLD-MRI had a sensitivity of 88% and a specificity of 47% to correctly classify severe stenoses. Adenosine thallium SPECT data from distal segments of the same coronary territory were also correlated with BOLD-MRI. However, variability was substantial. Conclusions—In patients with stress-induced angina, adenosine BOLD-MRI detects myocardial ischemia in myocardial segments related to severe coronary stenoses. Its potential will increase with additional improvement of spatial coverage and image quality.

Measurement of left ventricular dimensions and function in patients with dilated cardiomyopathy

Studies on medical therapy in heart failure are focused on changes of left ventricular (LV) dimensions and function. These changes may be small, requiring a large study group. We measured LV parameters (LV volumes, LV ejection fraction (LV‐EF), and left ventricular mass (LVM)) with two‐dimensional echocardiography (2D‐echo) and magnetic resonance imaging (MRI) in 50 patients. Based on the difference between the measurements, we determined the variance of the results and calculated the sample sizes needed to detect changes of baseline values. For the calculated and measured parameters we found significant differences between the two techniques: LV‐EF and LVM were higher in 2D‐echo, and LV dimensions were comparable. The sample size to detect relevant changes from baseline with MRI was significantly (P < 0.01) smaller than in 2D‐echo. We conclude that MRI is superior in clinical studies on left ventricular dimensional and functional changes, since measurements are more reproducible and the required sample size is substantially smaller, thereby reducing costs. J. Magn. Reson. Imaging 2001;13:367–371.