Clinical characteristics and role of early cardiac magnetic resonance imaging in patients with suspected ST-elevation myocardial infarction and normal coronary arteries

A variety of conditions other than acute myocardial infarction may cause ST-elevation. Our objective was to evaluate the impact of cardiac magnetic resonance (CMR) on differential diagnosis from a prospective series of patients with suspected ST-elevation myocardial infarction (STEMI) and completely normal coronary arteries. Among 1,145 patients with suspected STEMI, 49 patients had completely normal coronary arteries and entered a prospective registry. CMR was done within 24 h, if possible, and included function analyses, T2-weighted imaging (T2 ratio), T1-weighted imaging before and after gadolineum administration (global relative enhancement; gRE), and late gadolineum enhancement (LGE). All patients were asked for a follow-up CMR after approximately 3 months. The incidence of patients with suspected STEMI and normal coronary arteries was 4.3% and mean age was 45 ± 14 years (STEMI group 64 ± 13 years; P < 0.001). 55% had a recent history of infection. Cardiac biomarkers showed a moderate elevation on admission. There was a significant change from baseline to follow-up for LV end-diastolic volumes (EDV) (P < 0.001), LV mass (P < 0.05), mean T2 ratio (P < 0.05), and LGE volume (P < 0.05). Major diagnostic groups were myocarditis (29%), pericarditis (27%), and takotsubo cardiomyopathy (10%). 18% were regarded as non-diagnostic. The study showed an incidence of 4.3% of patients with suspected STEMI and completely normal coronary arteries. Early CMR was valuable in the evaluation of the differential diagnoses and to exclude myocardial abnormalities in patients with uncertain aetiology. Further studies are needed for the assessment of long-term outcome.     

Assessment of acute myocarditis by cardiovascular MR: diagnostic performance of shortened protocols

The recommended cardiovascular magnetic resonance (CMR) diagnostic criteria for active myocarditis (“Lake Louise Criteria”) are based on edema-sensitive (T2-weighted) imaging and two different contrast-enhanced techniques, the early gadolinium enhancement ratio (EGEr) and late gadolinium enhancement (LGE). Because fast spin echo sequences used for determining the EGEr and edema-sensitive T2-weighted sequences have inconsistent image quality, these components are often skipped in institutional standard protocols. We aimed to compare the diagnostic performance of the Lake Louise Criteria with and without T2-weighted or early gadolinium-enhanced CMR imaging in a clinical setting. We investigated 35 patients with suspected acute myocarditis (27 males; Age 39.8 ± 16.6) and 10 healthy controls (5 males; age 33.8 ± 10.4). CMR sequences investigated included an edema-sensitive short-T1 triple inversion recovery, T1-weighted turbo spin echo imaging before and within 4 min after gadolinium injection (EGEr), and a phase sensitive inversion-recovery gradient echo sequence 5–10 min after gadolinium injection (LGE). Quantitative and qualitative image analyses, respectively, were performed for EGEr and areas with increased signal in LGE and edema-sensitive images. EGEr, T2, and LGE burden were significantly higher in patients than in controls (EGEr: 5.8 ± 3.0 vs. 2.5 ± 1.7; p = 0.002, T2: 24 vs. 0; p < 0.001, LGE: 27 vs. 4; p < 0.05). The sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic accuracy were as follows: EGEr: 66, 90, 96, 43, and 72 %; T2: 69, 100, 100, 53, and 76 %; LGE: 77, 60, 87, 43 and 73 %; T2 and/or LGE: 91, 60, 89, 67, 84 % Lake Louise Criteria, “two out of three”: 80, 90, 96, 53, and 82 %. The sensitivity of “T2 and/or LGE” was significantly higher than the Lake Louise Criteria (p < 0.05), while the overall diagnostic accuracy was not statistically different. The overall diagnostic accuracy “T2 and/or LGE” was significantly better than that of LGE alone. The positive likelihood ratio was higher for the Lake Louise Criteria (7.7) than for EGE alone (6.3), T2 and/or LGE (2.3) or LGE alone (1.9). In patients with clinical evidence for relevant active myocarditis, skipping T2-weighted imaging or early GD enhancement is associated with a significantly lower positive likelihood ratio, while the removal of Early Gd Enhancement imaging does not change diagnostic overall accuracy, while reducing sensitivity. Thus, in patients where a high positive likelihood ratio is needed, the full Lake Louise Criteria including Early Gd enhancement and edema-sensitive T2-weighted imaging should be used until alternative approaches are developed.     

Myocardial edema in acute myocarditis: relationship of T2 relaxometry and late enhancement burden by using dual-contrast turbo spin-echo MRI

To quantify myocardial edema by using a T2 relaxometry approach with a dual-contrast turbo spin-echo (dcTSE) sequence in patients with acute myocarditis regarding focal late gadolinium enhancement (LGE) burden. CMR T2 relaxometry was performed in 39 patients (age 41?±?19 years; 36% women) with LGE in a typical myocarditis pattern and in ten healthy volunteers (age 46?±?12; 60% woman). dcTSE sequence (echo time 29 and 75 ms, respectively) was used for T2 mapping, analysis were performed on the basis of region of interest (ROI). Myocardial T2 relaxation times (T2 RT) in patients-ROI with focal LGE were significantly (p?<?0.001) higher than T2 RT in patients—ROI without apparent LGE pattern (65 ms (IQR 36–95) vs. 60 ms (IQR 26–88), respectively). T2 RT in healthy volunteers [55 ms (IQR 35–71)] were significantly lower than in patients ROI with or without focal LGE-pattern (p?<?0.001, respectively). T2 RT assessed by dcTSE are significantly higher in patients segments with and without focal LGE compared to normal controls, supporting a global myocardial inflammatory process in acute myocarditis. Furthermore, this quantitative T2-mapping approach highlights the potential to identify patients with diffuse myocarditis.     

Incremental value of cardiac deformation analysis in acute myocarditis: a cardiovascular magnetic resonance imaging study

The aim of this study was to assess cardiac deformation patterns in myocarditis applying feature tracking imaging (FTI) to cardiovascular magnetic resonance (CMR) images. Thirty-six patients (31 males) with acute myocarditis and 36 age- and gender-matched healthy volunteers were studied. CMR examinations were performed in a 1.5 T MR-scanner including late gadolinium enhancement (LGE). FTI was applied to standard cine images of long and short axis views. Global peak circumferential, longitudinal and radial systolic strains as well as long axis strain (LAS) were measured. Patients showed significantly impaired global peak circumferential (?24.4?±?4.2?% vs. ?28.8?±?3.8?%, p?<?0.0001), longitudinal (?17.6?±?4.4?% vs. ?23.8?±?3.1?%, p?<?0.0001) and radial (26.1?±?5.4?% vs. 37.9?±?7.6?%, p?<?0.0001) systolic strains. Even patients with a preserved ejection fraction (pEF, ≥55?%) had significantly reduced longitudinal (?20.0?±?4.8?% vs. ?23.8?±?3.1?%, p?<?0.01) and radial (27.7?±?5.5?% vs. 37.9?±?7.6?%, p?<?0.0001) strains. The extent of LGE in patients did not correlate to their respective strains. Regarding the differentiation between patients and controls, the addition of global peak systolic strains to ejection fraction led to a significant improvement of the logistic regression model (χ² 48.7 vs. 71.5; p?<?0.001) resulting in a high AUC of 0.98. Applying previously published reference values, 75?% or 31?% of patients with pEF showed at least one strain value or a LAS, which fell below the limit of 1 or respectively 2 standard deviations from the reference mean value. Cardiac strains measured by CMR–FTI are significantly impaired in patients with acute myocarditis even in those with pEF. Therefore, strain assessment may improve the diagnostic accuracy of CMR for myocarditis.     

Relation between cardiac dimensions and peak oxygen uptake

Background

In the situation of acute coronary occlusion, the myocardium supplied by the occluded vessel is subject to ischemia and is referred to as the myocardium at risk (MaR). Single photon emission computed tomography has previously been used for quantitative assessment of the MaR. It is, however, associated with considerable logistic challenges for employment in clinical routine. Recently, T2-weighted cardiovascular magnetic resonance (CMR) has been introduced as a new method for assessing MaR several days after the acute event. Furthermore, it has been suggested that the endocardial extent of infarction as assessed by late gadolinium enhanced (LGE) CMR can also be used to quantify the MaR. Hence, we sought to assess the ability of endocardial extent of infarction by LGE CMR to predict MaR as compared to T2-weighted imaging.

Methods

Thirty-seven patients with early reperfused first-time ST-segment elevation myocardial infarction underwent CMR imaging within the first week after percutaneous coronary intervention. The ability of endocardial extent of infarction by LGE CMR to assess MaR was evaluated using T2-weighted imaging as the reference method.

Results

MaR determined with T2-weighted imaging (34 ± 10%) was significantly higher (p < 0.001) compared to the MaR determined with endocardial extent of infarction (23 ± 12%). There was a weak correlation between the two methods (r² = 0.17, p = 0.002) with a bias of -11 ± 12%. Myocardial salvage determined with T2-weighted imaging (58 ± 22%) was significantly higher (p < 0.001) compared to myocardial salvage determined with endocardial extent of infarction (45 ± 23%). No MaR could be determined by endocardial extent of infarction in two patients with aborted myocardial infarction.

Conclusions

This study demonstrated that the endocardial extent of infarction as assessed by LGE CMR underestimates MaR in comparison to T2-weighted imaging, especially in patients with early reperfusion and aborted myocardial infarction.     

Myocardial area at risk after ST-elevation myocardial infarction measured with the late gadolinium enhancement after scar remodeling and T2-weighted cardiac magnetic resonance imaging

To evaluate the myocardial area at risk (AAR) measured by the endocardial surface area (ESA) method on late gadolinium enhancement (LGE) cardiovascular magnetic resonance (CMR) when applied after scar remodeling (3 months after index infarction) compared to T2-weighted CMR imaging. One hundred and sixty nine patients with ST-elevation myocardial infarction, treated with primary percutaneous coronary intervention, underwent one CMR within 1 week after index treatment to determine the AAR with T2-weighted imaging and a second scan 3 months after to measure AAR with the ESA method. There was a moderate correlation between the two methods (r = 0.86; P < 0.001). The AAR was significantly higher measured with T2-weighted imaging than with the ESA methods (32 ± 11% of left ventricle (LV) vs. 26 ± 10%LV; P < 0.001). The mean difference was 6 ± 6%LV. Furthermore, the mean difference between the two methods was statistical higher in the patients with myocardial salvage index ≥0.90 than in the remaining patients (9 ± 8%LV vs. 6 ± 5%LV; P = 0.02). The ESA method performed after scar remodeling (3 months following STEMI) yields significantly lower AAR′s and myocardial salvage indices compared to the T2-weighted method. Therefore, T2-weighted CMR plus LGE is the method of choice to assess AAR and myocardial salvage index using CMR. However, the ESA method is an easy and valid method for determining AAR, which can be used in settings where T2-weighted imaging has not been obtained in the acute phase.     

Native T1-mapping detects the location,extent and patterns of acute myocarditis without the need for gadolinium contrast agents

Background

Acute myocarditis can be diagnosed on cardiovascular magnetic resonance (CMR) using multiple techniques, including late gadolinium enhancement (LGE) imaging, which requires contrast administration. Native T1-mapping is significantly more sensitive than LGE and conventional T2-weighted (T2W) imaging in detecting myocarditis. The aims of this study were to demonstrate how to display the non-ischemic patterns of injury and to quantify myocardial involvement in acute myocarditis without the need for contrast agents, using topographic T1-maps and incremental T1 thresholds.

Methods

We studied 60 patients with suspected acute myocarditis (median 3 days from presentation) and 50 controls using CMR (1.5 T), including: (1) dark-blood T2W imaging; >(2) native T1-mapping (ShMOLLI); (3) LGE. Analysis included: (1) global myocardial T2 signal intensity (SI) ratio compared to skeletal muscle; (2) myocardial T1 times; (3) areas of injury by T2W, T1-mapping and LGE.

Results

Compared to controls, patients had more edema (global myocardial T2 SI ratio 1.71 ± 0.27 vs.1.56 ± 0.15), higher mean myocardial T1 (1011 ± 64 ms vs. 946 ± 23 ms) and more areas of injury as detected by T2W (median 5% vs. 0%), T1 (median 32% vs. 0.7%) and LGE (median 11% vs. 0%); all p < 0.001. A threshold of T1 > 990 ms (sensitivity 90%, specificity 88%) detected significantly larger areas of involvement than T2W and LGE imaging in patients, and additional areas of injury when T2W and LGE were negative. T1-mapping significantly improved the diagnostic confidence in an additional 30% of cases when at least one of the conventional methods (T2W, LGE) failed to identify any areas of abnormality. Using incremental thresholds, T1-mapping can display the non-ischemic patterns of injury typical of myocarditis.

Conclusion

Native T1-mapping can display the typical non-ischemic patterns in acute myocarditis, similar to LGE imaging but without the need for contrast agents. In addition, T1-mapping offers significant incremental diagnostic value, detecting additional areas of myocardial involvement beyond T2W and LGE imaging and identified extra cases when these conventional methods failed to identify abnormalities. In the future, it may be possible to perform gadolinium-free CMR using cine and T1-mapping for tissue characterization and may be particularly useful for patients in whom gadolinium contrast is contraindicated.     

A fast and effective method to assess myocardial hyperemia in acute myocarditis by magnetic resonance

Current cardiac magnetic resonance (CMR) quantitative signs for the diagnosis of myocarditis include myocardial edema, fibrosis and myocardial hyperemia (Hyp). Methods for the assessment of Hyp are actually complex and time-consuming. To test a simple and fast method to assess Hyp, using contrast enhancement steady state free precession (ceSSFP) technique. CMR imaging at 1.5T was performed on 39 patients with diagnosis of acute myocarditis and in 20 healthy controls. Hyp was evaluated in systolic and diastolic frames (Hyp-SYS and Hyp-DIA) as areas of myocardial hyperintensity in ceSSFP images early after gadolinium injection. Myocardial edema was evaluated using T2-STIR images. Myocardial fibrosis was assessed in conventional late gadolinium enhancement (LGE) images. A value of ≤12.1 g of Hyp-DIA was obtained as cut-off of normality in healthy controls. Using this threshold, Hyp was detected in 30 patients (77 %) with myocarditis. LGE was detected in 36 patients (92 %), and myocardial edema in 38 (97 %) patients with myocarditis A linear relation was found between Hyp-DIA and the extent of myocardial edema (R² 0.48, 95 % CI 0.47–0.85, p < 0.001) and the extent of LGE (R² 0.41, 95 % CI 0.31–0.61, p < 0.001). Patients with hyperemia had higher levels of C-reactive protein (p < 0.001), a higher extent of LGE (p < 0.05) and a larger left atrial area (p < 0.05). ceSSFP sequence at CMR is a novel and fast method to assess myocardial hyperemia in patient with acute myocarditis. Compared with non-Hyp subjects, patients with Hyp had more signs of inflammation and myocardial damage.     

Early gadolinium enhancement in hypertrophic cardiomyopathy: a potential premature marker of myocardial damage

Early gadolinium enhancement (EGE), one CMR diagnostic criteria in acute myocarditis, has been related with hyperemia and capillary leakage. The value of EGE in hypertrophic cardiomyopathy (HCM) remains unknown. Our aim was to determine the prevalence of EGE in patients with HCM, and its relation with late gadolinium enhancement (LGE). The association of EGE with morphological and clinical parameters was also evaluated. Sixty consecutive patients with HCM and CMR from our center were included. All the clinical and complementary test information was collected prospectively in our HCM clinic. Left ventricular (LV) measurements were calculated from cine sequences. EGE and LGE were quantified with a dedicated software. Clinical events were collected from medical records. A slow wash-out pattern on EGE was detected in up to 68?% of the patients, being an isolated finding without LGE in 10 (16?%). This cohort showed a greater maximal LV wall thickness (20.1?±?4 vs. 18.1?±?3.5 mm, p?=?0.010) and asymmetry ratio (1.86?±?0.42 vs. 1.62?±?0.46; p?=?0.039). The percentage of EGE/slice and the difference with the percentage LGE/slice demonstrated a significant positive correlation with the maximal LV wall thickness (Rho 0.450 and 0.386 respectively). EGE also correlated with number of segments with LVH (LV hypertrophy) and the asymmetry ratio. Neither EGE nor LGE were associated with classical risk factors, the risk score for sudden cardiac death, or with major clinical events. EGE was a frequent finding in HCM, even in absence of LGE. This phenomenon showed a positive correlation with morphological markers of disease burden.     

Late gadolinium enhancement magnetic resonance imaging for the assessment of myocardial infarction: comparison of image quality between single and double doses of contrast agents

To compare the image quality of late gadolinium enhancement (LGE) cardiac magnetic resonance imaging (CMR) using a single dose of gadolinium contrast agent versus the conventional double dose for assessing myocardial infarction. This retrospective study examined 37 patients with chronic myocardial infarction who underwent LGE CMR using both inversion recovery (IR)-turbo fast low-angle shot magnitude-reconstructed and phase-sensitive images with two different dosages of gadolinium contrast agent: a single dose of 0.1 mmol/kg gadolinium-DTPA in 17 patients and a double dose of 0.2 mmol/kg in 20 patients. The contrast-to-noise ratio (CNR) and visual conspicuity between infarct and normal myocardium (CNR_{infarct-normal}, conspicuity_{infarct-normal}) and between infarct and left ventricular cavity (CNR_infarct-LVC, conspicuity_infarct-LVC) were compared. Interobserver agreement for the maximal transmural extent of infarction was also evaluated. CNR_{infarct-normal} was significantly higher with double-dose gadolinium contrast agent (15.5 ± 20.7 vs. 40.4 ± 16.1 in magnitude images and 9.5 ± 2.8 vs. 11.2 ± 2.7 in phase-sensitive images, P < 0.001) while conspicuity_{infarct-normal} showed no significant difference between the two groups (P > 0.05). Both CNR_infarct-LVC (7.7 ± 10.7 vs. ?6.6 ± 19.0 in magnitude images and 4.1 ± 2.3 vs. ?0.4 ± 4.1 in phase-sensitive images, P < 0.05) and conspicuity_infarct-LVC were significantly better with single-dose gadolinium contrast. Interobserver agreement for assessing the transmural extent of infarction was moderate in both groups: 0.591 for single-dose and 0.472 for double-dose. LGE CMR using a single dose of gadolinium contrast agent showed significantly better contrast between infarcted myocardium and left ventricular cavity lumen without a significant decrease in visual contrast between infarcted myocardium and normal myocardium, compared to a double dose.     

Late Gadolinium Enhancement of the Esophagus is Common on Cardiac MR Several Months after Pulmonary Vein Isolation: Preliminary Observations

Background: Pulmonary vein isolation (PVI) as a treatment for atrial fibrillation (AF) is commonly performed. This procedure can damage the esophagus. Late gadolinium enhancement (LGE) cardiovascular magnetic resonance imaging (CMR) offers noninvasive assessment of scar. We sought to examine the prevalence of esophageal hyperenhancement on LGE‐CMR prior to and following PVI. Methods: Seventy‐four patients underwent LGE‐CMR prior to and 1.7 ± 1.9 months post PVI for AF. Transmural esophageal hyperenhancement was visually assessed. The pre‐ and post PVI esophageal position was measured, relative to the vertebral body. Results: Prior to PVI, 3% (2/74) of patients had esophageal LGE on CMR. At post‐PVI follow‐up, 30% (23/74) of the studies demonstrated new esophageal hyperenhancement adjacent to an ablation site. Most (74%, 17/27) positive esophageal LGE studies were performed >30 days after PVI, while no (0/9) studies performed >2 months post PVI were positive for esophageal hyperenhancement. The presence of post‐procedural esophageal hyperenhancement was not associated with longer ablation time (P = 0.42), use of an irrigated catheter (74% with LGE vs 47% without, P = 0.16), right‐sided esophageal location (56% with LGE vs 39% without, P = 0.17), size of left atrium cavity (58 ± 8 mm with LGE vs 61 ± 10 mm without, P = 0.15), or the timing of the LGE‐CMR study after PVI (36 ± 10 days with LGE vs 60 ± 66 days without, P = 0.09). Conclusion: Though rare before PVI, new esophageal LGE is seen in almost one‐third of patients after PVI. The clinical implications to remain to be explored, but clinicians should be aware of this frequent imaging finding. (PACE 2010; 33:661–666)     

Myocardial scar extent evaluated by cardiac magnetic resonance imaging in ICD patients: relationship to spontaneous VT during long-term follow-up

Patients with ischemic cardiomyopathy have an increased risk for ventricular arrhythmia, since myocardial infarction can be the substrate for re-entrant arrhythmias. Contrast-enhanced cardiac magnetic resonance imaging (CMR) has proven to reliably quantify myocardial infarction. Aim of our study was to evaluate correlations between functional and contrast-enhanced CMR findings and spontaneous ventricular tachy-arrhythmias in patients with ischemic cardiomyopathy who underwent implantable cardioverter-defibrillator (ICD) therapy. Forty-one patients with ischemic cardiomyopathy and indication for ICD therapy underwent cine and late gadolinium enhancement CMR for quantification of left ventricular volumes, function and scar tissue before subsequent implantation of ICD device. During a follow-up period of 1184 ± 442 days 68 monomorphic and 14 polymorphic types of ventricular tachycardia (VT) could be observed in 12 patients. Patients with monomorphic VT had larger scar volumes (25.3 ± 11.3 vs. 11.8 ± 7.5% of myocardial mass, P < 0.05) than patients with polymorphic VT. Moreover myocardial infarction involved more segments in the LAD perfusion territory (86 vs. 20%, P < 0.05) than in patients with polymorphic VT. Patients with spontaneous monomorphic VT during the long-term follow-up period had more infarcted tissue, which was more often present in the LAD perfusion territory than patients with polymorphic events. These data strengthen the diagnostic benefit of CMR in patients with ischemic cardiomyopathy. CMR may be used for better risk stratification in patients with ischemic cardiomyopathy undergoing ICD therapy.     

Late gadolinium enhancement gray zone in patients with hypertrophic cardiomyopathy. Comparison of different gray zone definitions

To quantify heterogeneous tissue at the periphery of areas of fibrosis (gray zone) in patients with hypertrophic cardiomyopathy (HCM) with the use of two different techniques. Cardiac magnetic resonance with late gadolinium enhancement analysis was performed in 33 patients with HCM. Gray zone was evaluated with the use of two different techniques previously described in patients after myocardial infarction. LGE was present in 25 (78%) patients. There was no significant difference in total LGE mass at two different cut-off values [53.8 g (interquartile range, IQR 43.5–77.8 g) vs. 53.8 g (IQR 37.8–64.5 g), respectively, P = 0.49]. Significant difference in gray zone mass assessed with the use of two techniques was demonstrated (19.1 ± 7.3 g vs. 50.8 ± 47.8 g; P = 0.003). There was a strong correlation between total LGE and gray zone mass (r = 0.789, P = 0.0001 for first method and r = 0.951, P < 0.0001 for the second one, respectively). However, significant variability of gray zone mass (and extent expressed as % of left ventricular mass) in patients with similar LGE size/extent was observed. Moreover, LGE mass varied greatly in patients with similar gray zone size. Neither left ventricular mass, nor with maximal wall thickness correlated with extent of gray zone assessed with both methods. The studied techniques provided similar results with regard to total LGE but significant differences were observed in gray zone mass. Two patients may have similar extent (or absolute mass) of LGE, but strikingly discrepant gray zone size.     

Prognostic value of combined magnetic resonance myocardial perfusion imaging and late gadolinium enhancement

Late gadolinium enhancement (LGE) and myocardial perfusion study by cardiac magnetic resonance (CMR) have a diagnostic and prognostic value in patients with suspected coronary artery disease (CAD). The purpose of this study was to determine the prognostic value of combined myocardial perfusion CMR and LGE in patients with known or suspected CAD. We studied patients with known or suspected CAD. All patients underwent CMR for functional study, myocardial perfusion and LGE. Myocardial ischemia by CMR was defined as a perfusion defect in patients without LGE or a perfusion defect beyond the LGE area. Patients were followed up for cardiovascular outcomes including hard cardiac events (cardiac death or non-fatal myocardial infarction) and major adverse cardiac events (MACE) which included cardiac death, non-fatal myocardial infarction, hospitalization for unstable angina, and heart failure. There were a total of 587 men and 645 women. Average age was 64.6 ± 11.1 years. LGE was detected in 326 patients (26.5%). Myocardial ischemia by CMR was detected in 423 patients (34.3%). Average follow-up duration was 34.9 ± 15.6 months. Univariate analysis showed that age, diabetes, use of beta blocker, left ventricular ejection fraction, left ventricular mass, wall motion abnormality, LGE, and myocardial ischemia are predictors for hard cardiac events and MACE. Multivariable analysis revealed that myocardial ischemia was the strongest predictor for hard cardiac events and MACE. Other independent predictors were age, use of beta blocker, and left ventricular mass. Myocardial ischemia by CMR has an incremental prognostic value for cardiac events in patients with known or suspected CAD.     

Performance of native and contrast-enhanced T1 mapping to detect myocardial damage in patients with suspected myocarditis: a head-to-head comparison of different cardiovascular magnetic resonance techniques

Myocardial T1 mapping is a novel technique that has proven to be superior to standard imaging for differentiation between healthy individuals in acute myocarditis. Aim of this study was comparison of T1 mapping with a clinical biomarker. We retrospectively investigated 171 patients undergoing cardiovascular magnetic resonance (CMR) examination with suspected myocarditis by performing native and contrast enhanced T1-mapping. Additionally, T2w and T1w images and late gadolinium enhancement sequences (LGE) were utilized for myocardial evaluation; Lake Louise Criteria comprise T1w, T2w and LGE imaging in a score. Reference for positive myocarditis diagnosis was a ten-fold increase of troponin level above normal (0.14 ng/ml). Native T1 and extracellular volume (ECV) showed good association with relevant troponin elevations. Area under the curve (AUC) was 81% (p?=?0.0001) for native T1 with an optimal threshold of 979 ms and 86% (p?<?0.0001) for ECV with an optimal cutoff of 32.4%. AUC for T2w imaging (T2-signal intensity ratio to skeletal muscle) was 77% (p?=?0.0003). AUC for T2w imaging (T2-signal intensity compared to remote myocardium) was 69% (p?=?0.012). Additionally, we found positive correlation for native T1 and ECV with the Lake Louise Criteria (r?=?0.44, p?=?0.0001 for native T1 and r?=?0.45, p?=?0.0001 for ECV). Correlated to troponin as biomarker, ECV and native T1 mapping perform at least equally well in comparison to established CMR-techniques LGE, T2w imaging and the combined Lake Louise Criteria in detecting acute myocardial damage. Normal ECV values rule out myocardial damage with very high certainty. T1 mapping qualifies for further prospective evaluations to evolve as a separate biomarker.     

Cardiovascular magnetic resonance of the myocardium at risk in acute reperfused myocardial infarction: comparison of T2-weighted imaging versus the circumferential endocardial extent of late gadolinium enhancement with transmural projection

Background

In the situation of acute coronary occlusion, the myocardium supplied by the occluded vessel is subject to ischemia and is referred to as the myocardium at risk (MaR). Single photon emission computed tomography has previously been used for quantitative assessment of the MaR. It is, however, associated with considerable logistic challenges for employment in clinical routine. Recently, T2-weighted cardiovascular magnetic resonance (CMR) has been introduced as a new method for assessing MaR several days after the acute event. Furthermore, it has been suggested that the endocardial extent of infarction as assessed by late gadolinium enhanced (LGE) CMR can also be used to quantify the MaR. Hence, we sought to assess the ability of endocardial extent of infarction by LGE CMR to predict MaR as compared to T2-weighted imaging.

Methods

Thirty-seven patients with early reperfused first-time ST-segment elevation myocardial infarction underwent CMR imaging within the first week after percutaneous coronary intervention. The ability of endocardial extent of infarction by LGE CMR to assess MaR was evaluated using T2-weighted imaging as the reference method.

Results

MaR determined with T2-weighted imaging (34 ± 10%) was significantly higher (p < 0.001) compared to the MaR determined with endocardial extent of infarction (23 ± 12%). There was a weak correlation between the two methods (r² = 0.17, p = 0.002) with a bias of -11 ± 12%. Myocardial salvage determined with T2-weighted imaging (58 ± 22%) was significantly higher (p < 0.001) compared to myocardial salvage determined with endocardial extent of infarction (45 ± 23%). No MaR could be determined by endocardial extent of infarction in two patients with aborted myocardial infarction.

Conclusions

This study demonstrated that the endocardial extent of infarction as assessed by LGE CMR underestimates MaR in comparison to T2-weighted imaging, especially in patients with early reperfusion and aborted myocardial infarction.     

Is contrast-enhanced cardiac magnetic resonance imaging at 3 T superior to 1.5 T for detection of coronary artery disease?

The aim is to compare a compiled clinical routine cardiac magnetic resonance (CMR) imaging protocol performed at both 1.5 and 3 T in patients with suspected coronary artery disease (CAD) undergoing coronary X-ray angiography. CMR including adenosine perfusion and late gadolinium enhancement (LGE) at 1.5 T has been established for noninvasive detection of relevant CAD. However, little is known about the potential advantages of 3 T to detect CAD. Fifty-two evaluable patients (62.3 ± 10.2 years) were included into the study. All patients were scanned at both 1.5 and 3 T including adenosine stress and rest perfusion, and LGE imaging. CMR images were analyzed by two blinded readers in consensus. X-Ray angiography served as the reference method. A significant CAD was diagnosed by quantitative coronary analysis. Diagnostic accuracy of the combined analysis of perfusion and LGE imaging yielded better values at 1.5 and 3 T than the analysis of perfusion images alone. Specificity and sensitivity at 3 T was superior to 1.5 T in detecting coronary stenoses ≥50 % (90 vs. 75 % and 84.4 vs. 75 %) and ≥70 % (88 vs. 80 % and 96.3 vs. 88.9 %). This study showed that CMR at 3 T in a routine clinical setting is superior to 1.5 T in detection of significant CAD. 3 T might become the preferred CMR field strength for evaluation of CAD in clinical practice.     

Correspondence between gated SPECT and cardiac magnetic resonance quantified myocardial wall thickening

Left ventricular (LV) wall thickening (WT) assessed from myocardial perfusion (MP) gated SPECT data has been reported to be a marker of functional recovery following myocardial damage. However, the accuracy of WT measurements obtained in the clinical setting rarely has been validated against an independent quantitative reference standard. The purpose of this investigation was to assess the degree to which quantified MP WT agrees with cardiac magnetic resonance (CMR) WT measurements, and to determine whether quantitation is as accurate as visual analysis in detecting abnormal regional WT. MP and ECG-gated True-FISP CMR data were analyzed for 20 patients evaluated after myocardial infarction (age 60 ± 11 years; 95% males). An experienced observer visually graded MP WT on a 5-point scale while viewing MP cines. MP WT was quantified using “Emory Cardiac Toolbox” (ECTb) algorithms. MP algorithms isolated myocardial counts and generated polar maps of WT. CMR data were analyzed by Medis “MASS” software. Manually drawn endocardial and epicardial contours were used to compute WT on CMR. CMR data also were processed for 10 age-matched normal volunteers to define the CMR WT threshold of abnormality. All computations were sampled into conventional 17 ACC/AHA LV wall segments. Receiver operating characteristics (ROC) curve analysis provided discrimination thresholds for optimal accuracy, which subsequently were used to dichotomize the MP methods. WT abnormalities also were assessed for the 3 major arterial territories, and for total numbers of abnormal segments per patient. 25% of all segments had abnormally low WT by CMR. While MP quantitation underestimated CMR WT values for segments with normal WT (26 ± 13% vs. 56 ± 28%, P < 0.0001), measurements were similar for segments with abnormal WT (4 ± 12% vs. 5 ± 9%, P = 0.45). On a segment-by-segment basis, detection of abnormal WT was more accurate by quantitative than visual analysis both for continuous variables (ROC area = 88 ± 2% vs. 80 ± 3%, P < 0.0001) and for dichotomized methods (83% vs. 76%, P = 0.04). Agreement of MP versus CMR for discriminating segments with normal from abnormal WT was significantly better for quantitative than visual analysis (κ = 0.59 vs. 0.40, P < 0.0001), with strongest agreement for left anterior descending artery territories (κ = 0.72). Total numbers of segments with abnormal WT per patient demonstrated significant correlation with CMR (r = 0.83, P < 0.0001). MP quantified LV ejection fractions and volumes also correlated well with CMR (r = 0.87 and 0.90, respectively). Quantified MP WT measurements correlated significantly with CMR values, and discriminated segments with abnormal WT from segments with normal WT more accurately than visual analysis. Therefore, quantification should be performed when analyzing regional WT by scintigraphy.     

Effect of iron overload on exercise capacity in thalassemic patients with heart failure

In b-thalassemia, myocardial iron overload contributes to heart failure, despite chelation treatment. We hypothesized that myocardial T2*, an index of iron overload, influences patients’ physical activity. We assessed a thalassemic population by both cardiovascular magnetic resonance imaging (CMR) and ergospirometry test. Sixty-six thalassemic patients aged 27 (19–40) years, 30 without (NHF) and 36 with heart failure (HF), were studied. Cardiac T2* and left ventricular ejection fraction (LVEF) were evaluated using a 1.5 T system. VO_2max, AT, Mets and duration of exercise by ergospirometry were also assessed. Myocardial T2* was lower in HF compared to NHF patients (14.7 ± 6.6 vs. 39 ± 2 ms, P < 0.001). LVEDV and LVESV were higher in HF group compared to NHF patients (139.9 ± 16.3 vs. 124.6 ± 20.86 ml, P < 0.01 and 94.9 ± 24 vs. 38.3 ± 10.1 ml, P < 0.001, respectively). Additionally, LVEF in HF was lower compared to NHF patients (21.3 ± 6.1% vs. 69.6 ± 3.7, P < 0.001, respectively). All exercise parameters were lower in HF compared to NHF patients (P < 0.001). Patients within the HF group were additionally analyzed according to T2* values (<10 ms). HF patients with T2* < 10 ms (n = 13) were considered as high iron overloaded (HF-H) and the rest of them (n = 23) as (HF-L). Although LVEDV, LVESV, LVEF were similar in the two subgroups, the exercise parameters were significantly lower in the HF-H group (P < 0.001). Heart T2* correlated with all exercise parameters (P < 0.001). HF thalassemic patients have reduced exercise indexes compared to non HF. Myocardial iron overload, expressed as T2*, has a direct influence on exercise capacity, independent of LV ejection fraction and functional class.