Clinical feasibility study for detection of myocardial oedema by a cine SSFP sequence in comparison to a conventional T2-weighted sequence

Radiomics-based detection of acute myocardial infarction on noncontrast enhanced midventricular short-axis cine CMR images

Cardiac magnetic resonance cine images are primarily used to evaluate functional consequences, whereas limited information is extracted from the noncontrast pixel-wise myocardial signal intensity pattern. In this study we want to assess whether characterizing this inherent contrast pattern of noncontrast-enhanced short axis (SAX) cine images via radiomics is sufficient to distinguish subjects with acute myocardial infarction (AMI) from controls. Cine balanced steady-state free-precession images acquired at 1.5 T from 99 AMI and 49 control patients were included. First, radiomic feature extraction of the left ventricular myocardium of end-diastolic (ED) and end-systolic (ES) frames was performed based on automated (AUTO) or manually corrected (MAN) segmentations. Next, top features were selected based on optimal classification results using a support vector machine (SVM) approach. The classification performances of the four radiomics models (using AUTO or MAN segmented ED or ES images), were measured by AUC, classification accuracy (CA), F1-score, sensitivity and specificity. The most accurate model was found when combining the features RunLengthNonUniformity, ClusterShade and Median obtained from the manually segmented ES images (CA = 0.846, F1 score = 0.847). ED analysis performed worse than ES, with lower CA and F1 scores (0.769 and 0.770, respectively). Manual correction of automated contours resulted in similar model features as the automated segmentations and did not improve classification results. A radiomics analysis can capture the inherent contrast in noncontrast mid-ventricular SAX cine images to distinguishing AMI from healthy subjects. The ES radiomics model was more accurate than the ED model. Manual correction of the autosegmentation did not provide significant classification improvements.

Signal decay mapping of myocardial edema using dual-contrast fast spin-echo MRI

PURPOSE

To introduce a dual-contrast fast spin-echo (dcFSE) sequence for signal decay mapping of myocardial edema.

MATERIALS AND METHODS

After consultation with the Institutional Review Board, 22 acute myocardial infarction (MI) patients were examined with magnetic resonance imaging (MRI) at 1.5T 2 days after revascularization. Edema was evaluated in 16 myocardial segments with an exponential fit for signal decay time (SDT) in dcFSE mapping and T2 signal intensity ratio for single-contrast FSE. Myocardial viability was evaluated in late gadolinium enhancement (LGE). A control group of 10 volunteers was examined for edema imaging. SDT was compared in segment groups: 1) with LGE in MI, 2) penumbra, 3) remote from LGE, 4) controls. Groups 1/3 and 3/4 were tested on difference. Three phantoms providing similar T2 but different T1 relaxation times (low, intermediate, high) were examined with dcFSE and multicontrast spin echo sequence as a reference.

RESULTS

The SDT/T2 ratio for segment groups was 1) 82msec/1.7 in segments with LGE; 2) 65msec/1.6 for penumbra, 3) 62msec/1.7 for remote segments, and 4) 50msec/1.6 in controls. In dcFSE group 1/3 (P < 0.0001) and in group 3/4 (P = 0.0002) SDT was significantly different. In single-contrast FSE the T2 ratio was not significantly different for both tests: 1/3 P = 0.1889; 3/4 P = 0.8879. T2 -overestimation of dcFSE was 23% in low, 29% in intermediate, and 35% in highly T1 contaminated phantoms.

CONCLUSION

dcFSE signal decay edema mapping is feasible in volunteers and patients. DcFSE SDT is superior to T2 ratio for detection of high-grade and diffuse myocardial edema. J. Magn. Reson. Imaging 2016;44:186-193.

Cardiac magnetic resonance assessment of takotsubo cardiomyopathy

Takotsubo cardiomyopathy is an important condition that can be difficult to differentiate from acute coronary syndrome on the basis of clinical, electrocardiogram, and cardiac enzyme assessment alone. Although coronary angiography remains important in the acute assessment of patients with suspected takotsubo cardiomyopathy, cardiac magnetic resonance (CMR) has emerged over the last decade as an important non-invasive imaging tool in the diagnosis and follow-up of this condition. We present a review highlighting the CMR features of takotsubo cardiomyopathy and its complications with particular focus on differentiating this condition from acute myocardial infarction and myocarditis.

Mapping the future of cardiac MR imaging: case-based review of T1 and T2 mapping techniques

Cardiac magnetic resonance (MR) imaging has grown over the past several decades into a validated, noninvasive diagnostic imaging tool with a pivotal role in cardiac morphologic and functional assessment and tissue characterization. With traditional cardiac MR imaging sequences, assessment of various pathologic conditions ranging from ischemic and nonischemic cardiomyopathy to cardiac involvement in systemic diseases (eg, amyloidosis and sarcoidosis) is possible; however, these sequences are most useful in focal myocardial disease, and image interpretation relies on subjective qualitative analysis of signal intensity. Newer T1 and T2 myocardial mapping techniques offer a quantitative assessment of the myocardium (by using T1 and T2 relaxation times), which can be helpful in focal disease, and demonstrate special utility in the evaluation of diffuse myocardial disease (eg, edema and fibrosis). Altered T1 and T2 relaxation times in disease states can be compared with published ranges of normal relaxation times in healthy patients. In conjunction with traditional cardiac MR imaging sequences, T1 and T2 mapping can limit the interpatient and interstudy variability that are common with qualitative analysis and may provide clinical markers for long-term follow-up.

Assessing myocardial recovery following ST-segment elevation myocardial infarction: short- and long-term perspectives using cardiovascular magnetic resonance

Myocardial recovery after revascularization for ST-segment elevation myocardial infarction (STEMI) remains a significant diagnostic and, despite novel treatment strategies, a therapeutic challenge. Cardiovascular magnetic resonance (CMR) has emerged as a valuable clinical and research tool after acute STEMI. It represents the gold standard for functional and morphological evaluation of the left ventricle. Gadolinium-based perfusion and late-enhancement viability imaging has expanded our knowledge about the underlying pathologies of inadequate myocardial recovery. T2-weighted imaging of myocardial salvage after early reperfusion of the infarct-related artery underlines the effectiveness of current invasive treatment for STEMI. In the last decade, the number of publications on CMR after acute STEMI continued to rise, with no plateau in sight. Currently, CMR research is gathering robust prognostic data on standardized CMR protocols with the aim to substantially improve patient care and prognosis. Beyond established CMR protocols, more specific methods such as magnetic resonance relaxometry, myocardial tagging, 4D phase-contrast imaging and novel superparamagnetic contrast agents are emerging. This review will discuss the currently available data on the use of CMR after acute STEMI and take a brief look at developing new methods currently under investigation.

Electrocardiographic findings and myocardial damage in acute myocarditis detected by cardiac magnetic resonance

Delayed-contrast-enhancement (DCE) magnetic resonance imaging (MRI) can identify areas of myocardial damage in patients with acute myocarditis (AM). The aim of this study was to assess the electrocardiographic findings in AM diagnosed by DCE-MRI. Eighty-one patients (72 men, 35 ± 13 years) with AM were prospectively enrolled. All of them underwent MRI and 12-lead-ECG recordings. In the admission electrocardiogram (ECG 1), as well as in that obtained 48 h later (ECG 2), the following parameters were analyzed: rhythm, PR, QRS, and QTc-intervals, intraventricular conduction, abnormal Q waves, ST segment elevation, and T wave inversion. On admission, 77 patients (95%) were in sinus rhythm, while four patients (6%) manifested severe arrhythmias. No difference between ECG 1 and ECG 2 was observed regarding abnormal Q waves, PR, QRS, and QTc-intervals. Electrocardiogram 1 was normal in 26 patients (32%, normal ECG group), and abnormal in 55 patients (68%, abnormal ECG group). ST elevation was found in 46 patients (57%), inverted T wave in seven patients (9%) and left bundle branch block (LBBB) in two patients (3%). Areas of DCE suggesting AM were found in each patient. No relationship concerning the location of the involved region (s) was found between ECG (leads with ST/T abnormalities) and MRI (areas showing DCE). The ECG in AM can either be normal or reflect abnormalities including arrhythmias, LBBB, ST segment elevation, and T wave inversion. The location of myocardial involvement deduced on the basis of ECG leads showing ST/T changes is not in close relationship with the areas of ventricular damage detected by MRI.

Electrocardiographic findings and myocardial damage in acute myocarditis detected by cardiac magnetic resonance

Delayed-contrast-enhancement (DCE) magnetic resonance imaging (MRI) can identify areas of myocardial damage in patients with acute myocarditis (AM). The aim of this study was to assess the electrocardiographic findings in AM diagnosed by DCE-MRI. Eighty-one patients (72 men, 35 ± 13 years) with AM were prospectively enrolled. All of them underwent MRI and 12-lead-ECG recordings. In the admission electrocardiogram (ECG 1), as well as in that obtained 48 h later (ECG 2), the following parameters were analyzed: rhythm, PR, QRS, and QTc-intervals, intraventricular conduction, abnormal Q waves, ST segment elevation, and T wave inversion. On admission, 77 patients (95%) were in sinus rhythm, while four patients (6%) manifested severe arrhythmias. No difference between ECG 1 and ECG 2 was observed regarding abnormal Q waves, PR, QRS, and QTc-intervals. Electrocardiogram 1 was normal in 26 patients (32%, normal ECG group), and abnormal in 55 patients (68%, abnormal ECG group). ST elevation was found in 46 patients (57%), inverted T wave in seven patients (9%) and left bundle branch block (LBBB) in two patients (3%). Areas of DCE suggesting AM were found in each patient. No relationship concerning the location of the involved region (s) was found between ECG (leads with ST/T abnormalities) and MRI (areas showing DCE). The ECG in AM can either be normal or reflect abnormalities including arrhythmias, LBBB, ST segment elevation, and T wave inversion. The location of myocardial involvement deduced on the basis of ECG leads showing ST/T changes is not in close relationship with the areas of ventricular damage detected by MRI.