Contrast-enhanced Cardiovascular Magnetic Resonance Imaging Research Articles

The Complex Pathophysiology of Acute Myocardial Infarction Imaged by Cardiovascular Magnetic Resonance

A 61-year-old man, an ex-smoker with a history of hypercholesterolemia, presented with crushing central chest pain radiating to the left arm, nausea, and cold sweat after consuming up to 2 g of recreational cocaine. ECG revealed Q waves in V1 through V3 with associated marginal ST-segment elevation of <1 mm (Figure 1). His troponin I level was 13.7 μg/L (normal range 0 to 0.04 μg/L). The patient was treated with dual antiplatelet therapy in addition to low-molecular-weight heparin and a calcium antagonist. He was referred for invasive coronary angiography, which demonstrated proximal occlusion of the left anterior descending artery (Figure 2) associated with anterior akinesia on ventriculography. To assess viability in this territory, myocardial perfusion scintigraphy and cardiovascular magnetic resonance (CMR) were requested. The myocardial perfusion scintigraphy images showed extensive full-thickness, anterior myocardial infarction involving the apex and the adjacent septum with evidence of peri-infarct ischemia in the basal anteroseptal segment (Figure 3). Gadolinium contrast-enhanced CMR imaging confirmed the anterior wall and septal akinesia (Movies I and …

Sudden Cardiac Arrest in Hypertrophic Cardiomyopathy in the Absence of Conventional Criteria for High Risk Status

Two patients with hypertrophic cardiomyopathy are reported from the recent experience of the Hypertrophic Cardiomyopathy Center of the Minneapolis Heart Institute Foundation, demonstrating limitations in the risk stratification algorithm currently used for this disease. One patient, an asymptomatic 21-year-old male college student, was prophylactically implanted with a cardioverter-defibrillator. This decision was based largely on the presence of apparent extensive myocardial fibrosis identified by contrast-enhanced cardiovascular magnetic resonance imaging, currently not considered a risk factor in this disease. Fifteen months later, ventricular fibrillation was interrupted by an appropriate defibrillator shock. The other patient, an asymptomatic 15-year-old male subject without any apparent high-risk markers, died suddenly at home. Necropsy examination of the heart identified scarring confined to portions of both left ventricular papillary muscles, possibly representing a substrate for ventricular tachyarrhythmias. In conclusion, these 2 cases demonstrate that present strategies for assessing high-risk status in hypertrophic cardiomyopathy are inadequate to identify all such patients. However, while the anecdotal nature of these observations cannot yet justify altering the general guidelines for implantation of defibrillators for the primary prevention of sudden death related to hypertrophic cardiomyopathy, 1 of our 2 cases suggests a future role for contrast-enhanced cardiovascular magnetic resonance in the risk stratification of this complex disease.

Right Ventricular Dysfunction Assessed by Cardiovascular Magnetic Resonance Imaging Predicts Poor Prognosis Late After Myocardial Infarction

We sought to determine whether right ventricular (RV) function late after myocardial infarction (MI) impacts long-term prognosis. Right ventricular failure predicts early mortality in patients with acute MI. The prognostic impact of RV function late after MI is not well defined. Accordingly, we determined whether RV dysfunction late after MI influences survival beyond traditional risk predictors, including patient age, left ventricular ejection fraction (LVEF), and infarct size. We studied 147 consecutive patients >30 days after MI (mean age of infarct 6.7 +/- 8.2 years) who were referred for contrast-enhanced cardiovascular magnetic resonance imaging. We assessed hazard ratios for death by RV ejection fraction (RVEF). The association of RVEF with mortality adjusted to traditional risk predictors was examined by using multivariable Cox proportional hazards regression models. A total of 26 deaths occurred during a median follow-up of 17 months (range 6 to 53 months). By univariable analysis, RVEF <40% was strongly associated with mortality (unadjusted hazard ratio 4.02; p = 0.0007). By multivariable analysis that adjusted for patient age, left ventricular (LV) infarct size, and LVEF, RVEF <40% remained a significant independent predictor of mortality (adjusted hazard ratio 2.86; p = 0.03). Right ventricular ejection fraction quantified late after MI is an important predictor of prognosis adjusted for patient age, LV infarct size, and LVEF. Accordingly, evaluation of RVEF using cardiovascular magnetic resonance imaging can improve risk-stratification and potentially refine patient management after MI.

Contrast-Enhanced Cardiovascular Magnetic Resonance Imaging of Right Ventricular Infarction

We assessed the role of late enhancement cardiovascular magnetic resonance imaging (LE-CMR) for the diagnosis of right ventricular infarction (RVI). Right ventricular infarction occurs in about one-half of patients with inferior myocardial infarction (MI). It is associated with an unfavorable prognosis, but established methods often lack the diagnostic accuracy to detect it. Late enhancement cardiovascular magnetic resonance imaging accurately detects left ventricular MI. Thirty-seven patients with acute inferior MI were included. To test for RVI, they prospectively underwent a physical examination, an electrocardiogram (ECG) for ST-segment elevation in the V4r right precordial lead, and an echocardiogram. After coronary reperfusion, LE-CMR was performed for assessing presence and extent of late enhancement in the right ventricular (RV) wall. The LE-CMR data were compared with the other results; interobserver variability was assessed. The LE-CMR was repeated after 13 months. Late enhancement cardiovascular magnetic resonance imaging detected RVI in 21 of 37 (57%) patients with acute inferior MI. Interobserver variability was very good (kappa 0.83); physical exam was positive for RVI in 7 of 37 (19%) patients, V4r ECG in 13 of 37 (35%) patients, and echocardiogram in 6 of 37 (16%) patients. The LE-CMR findings for RVI showed only mild agreement with findings for RVI on physical exam (kappa 0.30), V(4)r ECG (kappa 0.38), and echocardiography (kappa 0.32). Irreversible injury of the RV persisted at 13 months (kappa 0.85). In patients with acute inferior MI, RVI is more frequently detected by LE-CMR than by current standard diagnostic techniques. Further CMR studies might allow for analyzing its clinical and prognostic relevance.

Magnetic Resonance Angiography, Function and Viability Evaluation in Patients with Kawasaki Disease

We evaluated the ability of magnetic resonance imaging to perform a noninvasive assessment of coronary arteries, function and viability in one examination in a population with Kawasaki disease. Magnetic resonance angiography (MRA) can identify coronary abnormalities in patients with Kawasaki disease (KD). Contrast enhanced cardiovascular magnetic resonance (CeCMR) is the current gold standard for scar detection. Steady-state, free precession (SSFP) cine is a reliable technique to evaluate myocardial function and wall motion. Twenty patients with KD aged 7-12 yrs, were examined. Coronary MRA was performed using a 1.5 T system with two ECG-triggered pulse sequences. CeCMR images were acquired 15 minutes after the i.v. injection of 0.1 mmol/kg Gd-DTPA using an inversion recovery sequence. SSFP cines were acquired using 6-mm short-axis slices from the atrioventricular ring to the apex. Aneurysms of the coronary arteries were identified in 7 patients and coronary ectasia was present in the remaining 12 patients while 1 patient had both. Transmural anterior-apical scar was detected by ceCMR in two cases, while small inferior necrosis was identified in another 2 cases. Left ventricular function was deteriorated only in the two patients with antero-apical infarction. The presence of myocardial infarction was detected in the territory supplied by the involved coronary artery. In Kawasaki disease MRA, SSFP cine and ceCMR are able to perform noninvasive coronary artery evaluation, function and infarct detection in a single study.

Comparison Between Myocardial Contrast Echocardiography and Single-Photon Emission Computed Tomography for Predicting Transmurality of Acute Myocardial Infarction

Contrast-enhanced cardiovascular magnetic resonance imaging (CMR) has been shown to accurately assess transmural extent of infarction, which is an excellent predictor of long-term improvement in contractile function. We assessed the relative accuracy of myocardial contrast echocardiography (MCE) and single-photon emission computed tomography (SPECT) to predict transmural extent of infarction after acute myocardial infarction. MCE, SPECT, and CMR were performed in 40 patients with acute myocardial infarction 7 to 10 days after thrombolysis. CMR was used to divide the transmural extent of infarction into 5 groups: 0%, 1% to 25%, 26% to 50%, 51% to 75%, and 76% to 100% in dysfunctional segments. MCE and SPECT were compared with assessment grades of transmural extent of infarction. There was a significant relation (p<0.0001) between decreasing contrast intensity as assessed qualitatively by MCE and increasing transmural extent of infarction on CMR as was the case for SPECT. The accuracy of MCE (77%) to predict>50% transmural extent of infarction (nonviable myocardium) was significantly (p=0.02) superior to that of SPECT (70%). Absence of uptake on MCE and SPECT virtually ruled out <or=50% of the transmural extent of infarction (negative predictive values 93% and 89%, respectively). MCE was significantly more sensitive than SPECT in differentiating between <or=25% and>25% transmural extent of infarction (84% vs 76%, p=0.03). MCE and SPECT correlate well with the transmural extent of infarction. However, MCE is significantly more accurate in predicting >50% of the transmural extent of infarction and more sensitive in identifying <or=25% of the transmural extent of infarction than SPECT.

Assessment of reversible myocardial dysfunction in chronic ischaemic heart disease: comparison of contrast-enhanced cardiovascular magnetic resonance and a combined positron emission tomography–single photon emission computed tomography imaging protocol

The aim of the study was to compare, in patients with chronic ischaemic cardiomyopathy, contrast-enhanced cardiovascular magnetic resonance (ce-CMR) imaging and a combined (18)F-fluorodeoxyglucose ((18)F-FDG) positron emission tomography (PET) and (99m)Tc-sestamibi single-photon emission computed tomography (SPECT) protocols for the prediction of functional recovery after revascularization, as assessed by cine CMR. Twenty-nine patients with ischaemic cardiomyopathy (ejection fraction 32 +/- 10%) were investigated with ce-CMR and PET/SPECT. For the assessment of global and regional functions, cine CMR was performed at baseline and at 6 months follow-up. For ce-CMR, the segmental extent of hyperenhancement (SEH) was quantitated, and for PET/SPECT, different viability categories were defined according to a validated quantitative protocol. Functional improvement was related to the SEH by ce-CMR, as well as to the viability categories by PET/SPECT. Sensitivity and specificity for the prediction of functional recovery at follow-up was 97 and 68% for ce-CMR and 87 and 76% for PET/SPECT. The positive predictive value was identical for both techniques (73%). However, ce-CMR achieved a higher negative predictive value (93 vs. 77%, respectively), indicating that ce-CMR may be superior to PET/SPECT for the identification of segments unlikely to recover function after revascularization. Both methods had a similar yield in the prediction of global functional improvement. ce-CMR is comparable with a PET/SPECT imaging protocol for the prediction of regional and global functional improvement after revascularization. However, ce-CMR may be superior to nuclear imaging for the identification of segments that are unlikely to recover function at follow-up.

Concordance of Electrocardiographic Patterns and Healed Myocardial Infarction Location Detected by Cardiovascular Magnetic Resonance

Q-wave myocardial infarction (MI) location is generally based on a pathologic correlation first proposed >50 years ago. Despite the proved reliability of contrast-enhanced cardiovascular magnetic resonance (CE-CMR) imaging to detect and locate infarcted areas, no global study has been conducted with the aim of correlating the electrocardiographic (ECG) patterns of Q-wave MI with infarct location. We studied this correlation in 51 patients with ST-elevation acute coronary syndrome who presented with Q waves or equivalents during MI. Seven preestablished ECG patterns that matched with high specificity to 7 different MI locations as detected by CE-CMR imaging were used to assess its value in clinical practice to locate an infarcted area. There were 4 ECG patterns in the anteroseptal zone (23 patients; septal, apical, and/or anteroseptal, extensive anterior, and limited anterolateral) and 3 ECG patterns in the inferolateral zone (28 patients; lateral, inferior, and inferolateral). In conclusion, (1) the predefined ECG patterns we used matched well (86% global concordance) with their corresponding infarction areas as detected by CE-CMR imaging and have real value in clinical practice, and (2) the RS morphology in lead V(1) is due to lateral MI and the QS morphology in lead aVL is due to mid-anterior and mid-lateral MI. Therefore, the terms posterior and high lateral infarction are incorrect and should be changed to lateral wall and limited anterolateral wall MI.

Is Multislice Computed Tomography of Value for the Imaging of Myocardial infarction?

Evaluation of: Mahnken A, Koos R, Katoh M et al.: Assessment of myocardial viability in reperfused acute myocardial infarction using 16-slice computed tomography in comparison with magnetic resonance imaging. J. Am. Coll. Cardiol. 12, 2042-2047 (2005). Myocardial contrast-enhanced (CE) cardiovascular magnetic resonance (CMR) imaging is a relatively new and well-validated technique for imaging both cell damage and scar resulting from myocardial infarction. Multislice (16-slice) x-ray computed tomography (MSCT) has recently been suggested as a means for imaging acute myocardial infarction. Both CMR and MSCT are becoming increasingly available, are less invasive than catheter-based techniques and have high spatial three-dimensional resolution, allowing interrogation and sizing of acute myocardial infarction. The cell damage in acute myocardial infarction may be distinguished from normal myocardium by either technique. But while both CMR and MSCT show agreement for infarct localization and size determination, MSCT exposes the patient to substantial ionizing radiation and to possible kidney damage associated with the necessary administration of radio-opaque, iodinated, contrast medium. Furthermore MSCT does not demonstrate the presence of pathological consequences of myocardial infarction, myocardial scarring. These points must be considered when choosing the most appropriate approach for the imaging of acute and/or chronic myocardial infarction.

Relation of End-Diastolic Wall Thickness and the Residual Rim of Viable Myocardium by Magnetic Resonance Imaging to Myocardial Viability Assessed by Fluorine-18 Deoxyglucose Positron Emission Tomography

End-diastolic wall thickness (EDWT) and thickness of the residual non-contrast-enhanced myocardial rim have been suggested as markers for the assessment of myocardial viability by cardiovascular magnetic resonance (CMR) imaging. This study compared these parameters as derived from contrast-enhanced CMR images for the prediction of myocardial viability as determined by fluorine-18 deoxyglucose positron emission tomography (FDG-PET). Twenty-two patients with ischemic cardiomyopathy (ejection fraction 31 +/- 11%) were investigated. For contrast-enhanced CMR imaging, a standard inversion-recovery sequence was used. FDG-PET was performed using a hyperinsulinemic-euglycemic clamp. Data were analyzed with a 17-segment model. Of 146 severely dysfunctional segments, 112 were assessed as viable and 34 as nonviable by nuclear imaging. Using receiver-operator characteristic analysis, areas under the curve were 0.95 for unenhanced myocardial rim (95% confidence interval 0.92 to 0.98) and 0.86 for EDWT (95% confidence interval 0.80 to 0.93, p <0.001 vs unenhanced myocardial rim) for the prediction of viability as assessed by FDG-PET. Cutoffs of 5.4 mm for EDWT and 3.0 mm for unenhanced myocardial rim were found to optimally differentiate viability by FDG-PET. In 25 segments with divergent results, 94% of segments with an EDWT < or =5.4 mm and an unenhanced myocardial rim >3.0 mm were scored as viable by FDG-PET, whereas 57% of segments with an EDWT >5.4 mm and an unenhanced myocardial rim < or =3.0 mm were scored nonviable with the reference technique. In conclusion, unenhanced myocardial rim is superior to EDWT for the prediction of myocardial viability as determined by FDG-PET and may be clinically useful for assessment of myocardial viability in patients with ischemic cardiomyopathy and regional wall thinning.

Contrast enhanced-cardiovascular magnetic resonance imaging in patients with pulmonary hypertension

To determine the presence and extent of delayed contrast enhancement (DCE) in patients with pulmonary hypertension (PHT) using contrast enhanced-cardiovascular magnetic resonance imaging (ce-CMR). Twenty-five patients with PHT underwent ce-CMR and right heart catheterization. Right ventricular (RV) and left ventricular (LV) volumes, ejection fraction, mass, and DCE mass were determined with ce-CMR. Mean pulmonary artery pressure (mean PAP) averaged 43 (12) mmHg and cardiac output 4.3 (1.2) L/min. DCE was demonstrated in 23 out of 25 patients. DCE was confined to the RV insertion points (RVIPs) in seven patients and extended into the interventricular septum (IVS) in the remaining 16 patients. In these 16 patients, septal contrast enhancement was associated with IVS bowing. The extent of contrast enhancement correlated positively with RV end-diastolic volume/body surface area, RV mass, mean PAP, and pulmonary vascular resistance and correlated inversely with RV ejection fraction. DCE was present within the RVIPs and IVS of most patients with PHT studied. Extent of DCE correlated with RV function and pulmonary haemodynamics. DCE was associated with IVS bowing and may provide a novel marker for occult septal abnormalities directly relating to the haemodynamic stress experienced by these patients.

How reliable is electrocardiography in differentiating transmural from non-transmural myocardial infarction? A study with contrast magnetic resonance imaging as gold standard

Cardiovascular magnetic resonance (CMR) using contrast enhancement allows exact determination of the site and transmural extent of myocardial infarction (MI). We evaluated whether 12-lead electrocardiography can differentiate transmural from non-transmural MI or determine the site of MI by comparing the findings with those of contrast-enhanced CMR. A total of 27 patients (59.5±12.9 years) with a history of MI (6.4±2.9 months) underwent CMR (Magnetom, Siemens, Erlangen, Germany). Cine images were acquired in the horizontal and vertical long axes and short axis by TrueFISP. Contrast-enhanced CMR images were acquired in the same axes by segmented FLASH 15 min after administration of gadolinium–DTPA (0.15 mmol/kg). This showed the MI to be transmural in 11 patients and non-transmural in 16. An electrocardiogram (ECG) was recorded in all patients before CMR. T-wave alterations, descending ST-depression, pathological Q-waves and absent R waves were more frequent in non-transmural MI than transmural MI, as defined by contrast-enhanced CMR ( p≥0.618). However, none of the differences were statistically significant. R-wave reduction, q waves and horizontal ST-depression were more frequent in transmural than in non-transmural MI ( p≥0.157). Again, the differences were not significant. The sensitivity of the ECG for MI localization was highest in inferior infarctions (85.71%), the specificity was highest in anterior infarctions (100%), the best positive predictive value (80%) was achieved for anterolateral infarctions, and the best negative predictive value for lateral infarctions (95.83%). Transmural and non-transmural MI cannot be differentiated by ECG. The ECG is most accurate in detecting anterolateral MI.

Contrast-enhanced cardiovascular magnetic resonance imaging.

Since its introduction in the early 1990s, contrast-enhanced (CE) cardiac magnetic resonance imaging (MRI) has evolved rapidly for the assessment of cardiac pathologies, including in particular ischemic heart disease and inflammatory conditions. Likewise, CE-magnetic resonance angiography (MRA) is now used routinely to evaluate the thoracic vasculature. This article reviews the current use of extracellular gadolinium-based agents in CE cardiovascular imaging, focusing on ischemic heart disease, inflammatory myocardial conditions, and the use of CE-MRA in imaging of the pulmonary and aortic vasculature. Recent advances in fast and ultrafast MRI combined with the use of extracellular contrast media allow noninvasive measurements of multiple parameters of the cardiovascular system in less than 40 minutes. Beyond the assessment of left ventricular wall motion and morphology, CE cardiac MRI allows depiction of myocardial perfusion and thereby provides information regarding microvascular integrity and myocardial viability. The excellent spatial resolution of MRI, especially for the distinction of nontransmural versus transmural extent of pathology, has been shown to be superior to other modalities that are often nonlocalizing, nonspecific, or more invasive. Additional advantages of CE-MRA, particularly for the thoracic vasculature, include safety, its noninvasive character, large field of view, and the ability to demonstrate complicated three-dimensional relationships without the need for iodinated, nephrotoxic contrast media.

Contrast-enhanced MRI and routine single photon emission computed tomography (SPECT) perfusion imaging for detection of subendocardial myocardial infarcts: an imaging study

Myocardial infarcts are routinely detected by nuclear imaging techniques such as single photon emission computed tomography (SPECT) myocardial perfusion imaging. A newly developed technique for infarct detection based on contrast-enhanced cardiovascular magnetic resonance (CMR) has higher spatial resolution than SPECT. We postulated that this technique would detect infarcts missed by SPECT. We did contrast-enhanced CMR and SPECT examinations in 91 patients with suspected or known coronary artery disease. All CMR and SPECT images were scored, using a 14-segment model, for the presence, location, and spatial extent of infarction. To compare each imaging modality to a gold standard, we also acquired contrast-enhanced CMR and SPECT images in 12 dogs with, and three dogs without, myocardial infarction as defined by histochemical staining. In animals, contrast-enhanced CMR and SPECT detected all segments with nearly transmural infarction (>75% transmural extent of the left-ventricular wall). CMR also identified 100 of the 109 segments (92%) with subendocardial infarction (<50% transmural extent of the left-ventricular wall), whereas SPECT identified only 31 (28%). SPECT and CMR showed high specificity for the detection of infarction (97% and 98%, respectively). In patients, all segments with nearly transmural infarction, as defined by contrast-enhanced CMR, were detected by SPECT. However, of the 181 segments with subendocardial infarction, 85 (47%) were not detected by SPECT. On a per patient basis, six (13%) individuals with subendocardial infarcts visible by CMR had no evidence of infarction by SPECT. SPECT and CMR detect transmural myocardial infarcts at similar rates. However, CMR systematically detects subendocardial infarcts that are missed by SPECT.