A Noncontrast CMR Risk Score for Long-Term Risk Stratification in Reperfused ST-Segment Elevation Myocardial Infarction.

OBJECTIVES: This study compared the prognostic value of a noncontrast CMR risk score for the composite of all-cause death, nonfatal myocardial infarction, and new congestive heart failure. BACKGROUND: A cardiovascular magnetic resonance (CMR) risk score including left ventricular ejection fraction (LVEF), myocardial infarct (MI) size, and microvascular obstruction (MVO) was recently proposed to risk-stratify patients with ST-segment elevation myocardial infarction (STEMI). METHODS: The Eitel CMR risk score and GRACE (Global Registry of Acute Coronary Events) score were used as a reference (Score 1: acute MI size ≥19% LV, LVEF ≤47%, MVO >1.4% LV and GRACE score). MVO was replaced by intramyocardial hemorrhage (IMH) in Score 2 (acute MI size ≥19% LV, LVEF ≤47%, IMH, and GRACE score). Score 3 included only LVEF ≤45%, IMH, and GRACE score. RESULTS: There were 370 patients in the derivation cohort and 234 patients in the validation cohort. In the derivation cohort, the 3 scores performed similarly and better than GRACE score to predict the 1-year composite endpoint with C-statistics of 0.83, 0.83, 0.82, and 0.74, respectively. In the validation cohort, there was good discrimination and calibration of score 3, with a C-statistic of 0.87 and P = 0.71 in a Hosmer-Lemeshow test for goodness of fit, on the 1-year composite outcome. Kaplan-Meier curves for 5-year composite outcome showed that those with LVEF ≤45% (high-risk) and LVEF >45% and IMH (intermediate-risk) had significantly higher cumulative events than those with LVEF >45% and no IMH (low-risk), log-rank tests: P = 0.02 and P = 0.03, respectively. The HR for the high-risk group was 2.3 (95% CI: 1.1-4.7) and for the intermediate-risk group was 2.0 (95% CI: 1.0-3.8), and these remained significant after adjusting for the GRACE score. CONCLUSIONS: This noncontrast CMR risk score has performance comparable to an established risk score, and patients with STEMI could be stratified into low risk (LVEF >45% and no IMH), intermediate risk (LVEF >45% and IMH), and high risk (LVEF ≤45%). (A Trial of Low-dose Adjunctive alTeplase During prIMary PCI [T-TIME]; NCT02257294) (Detection and Significance of Heart Injury in ST Elevation Myocardial Infarction [BHF MR-MI]; NCT02072850).

Low-Dose Alteplase During Primary Percutaneous Coronary Intervention According to Ischemic Time.

BACKGROUND: Microvascular obstruction affects one-half of patients with ST-segment elevation myocardial infarction and confers an adverse prognosis. OBJECTIVES: This study aimed to determine whether the efficacy and safety of a therapeutic strategy involving low-dose intracoronary alteplase infused early after coronary reperfusion associates with ischemic time. METHODS: This study was conducted in a prospective, multicenter, parallel group, 1:1:1 randomized, dose-ranging trial in patients undergoing primary percutaneous coronary intervention. Ischemic time, defined as the time from symptom onset to coronary reperfusion, was a pre-specified subgroup of interest. Between March 17, 2016, and December 21, 2017, 440 patients, presenting with ST-segment elevation myocardial infarction within 6 h of symptom onset (<2 h, n = 107; ≥2 h but <4 h, n = 235; ≥4 h to 6 h, n = 98), were enrolled at 11 U.K. hospitals. Participants were randomly assigned to treatment with placebo (n = 151), alteplase 10 mg (n = 144), or alteplase 20 mg (n = 145). The primary outcome was the amount of microvascular obstruction (MVO) (percentage of left ventricular mass) quantified by cardiac magnetic resonance imaging at 2 to 7 days (available for 396 of 440). RESULTS: Overall, there was no association between alteplase dose and the extent of MVO (p for trend = 0.128). However, in patients with an ischemic time ≥4 to 6 h, alteplase increased the mean extent of MVO compared with placebo: 1.14% (placebo) versus 3.11% (10 mg) versus 5.20% (20 mg); p = 0.009 for the trend. The interaction between ischemic time and alteplase dose was statistically significant (p = 0.018). CONCLUSION: In patients presenting with ST-segment elevation myocardial infarction and an ischemic time ≥4 to 6 h, adjunctive treatment with low-dose intracoronary alteplase during primary percutaneous coronary intervention was associated with increased MVO. Intracoronary alteplase may be harmful for this subgroup. (A Trial of Low-Dose Adjunctive Alteplase During Primary PCI [T-TIME]; NCT02257294).

A comparison of cardiovascular magnetic resonance and single photon emission computed tomography (SPECT) perfusion imaging in left main stem or equivalent coronary artery disease: a CE-MARC substudy.

BACKGROUND: Assessment of left main stem (LMS) stenosis has prognostic and therapeutic implications. Data on assessment of LMS disease by cardiovascular magnetic resonance (CMR) and single photon emission computed tomography (SPECT) are limited. CE-MARC is the largest prospective comparison of CMR and SPECT against quantitative invasive coronary angiography (QCA) for detection of coronary artery disease (CAD), and provided the framework for this evaluation. The aims of this study were to compare diagnostic accuracy of visual and quantitative perfusion CMR to SPECT in patients with LMS stable CAD. METHODS: Fifty-four patients from the CE-MARC study were included: 27 (4%) with significant LMS or LMS-equivalent disease on QCA, and 27 age/sex-matched patients with no flow-limiting CAD. All patients underwent multi-parametric CMR, SPECT and QCA. Performance of visual and quantitative perfusion CMR by Fermi-constrained deconvolution to detect LMS disease was compared with SPECT. RESULTS: Of 27 patients in the LMS group, 22 (81%) had abnormal CMR and 16 (59%) had abnormal SPECT. All patients with abnormal CMR had abnormal perfusion by visual analysis. CMR demonstrated significantly higher area under the curve (AUC) for detection of disease (0.95; 0.85-0.99) over SPECT (0.63; 0.49-0.76) (p = 0.0001). Global mean stress myocardial blood flow (MBF) by CMR in LMS patients was significantly lower than controls (1.77 ± 0.72 ml/g/min vs. 3.28 ± 1.20 ml/g/min, p < 0.001). MBF of <2.08 ml/g/min had sensitivity of 78% and specificity of 85% for diagnosis of LMS disease, with an AUC (0.87; 0.75-0.94) not significantly different to visual CMR analysis (p = 0.18), and more accurate than SPECT (p = 0.003). CONCLUSION: Visual stress perfusion CMR had higher diagnostic accuracy than SPECT to detect LMS disease. Quantitative perfusion CMR had similar performance to visual CMR perfusion analysis.

Prognostic Value of Cardiovascular Magnetic Resonance and Single-Photon Emission Computed Tomography in Suspected Coronary Heart Disease: Long-Term Follow-up of a Prospective, Diagnostic Accuracy Cohort Study.

BACKGROUND: There are no prospective, prognostic data comparing cardiovascular magnetic resonance (CMR) and single-photon emission computed tomography (SPECT) in the same population of patients with suspected coronary heart disease (CHD). OBJECTIVE: To establish the ability of CMR and SPECT to predict major adverse cardiovascular events (MACEs). DESIGN: Annual follow-up of the CE-MARC (Clinical Evaluation of MAgnetic Resonance imaging in Coronary heart disease) study for a minimum of 5 years for MACEs (cardiovascular death, acute coronary syndrome, unscheduled revascularization or hospital admission for cardiovascular cause). (Current Controlled Trials registration: ISRCTN77246133). SETTING: Secondary and tertiary care cardiology services. PARTICIPANTS: 752 patients from the CE-MARC study who were being investigated for suspected CHD. MEASUREMENTS: Prediction of time to MACE was assessed by using univariable (log-rank test) and multivariable (Cox proportional hazards regression) analysis. RESULTS: 744 (99%) of the 752 recruited patients had complete follow-up. Of 628 who underwent CMR, SPECT, and the reference standard test of X-ray angiography, 104 (16.6%) had at least 1 MACE. Abnormal findings on CMR (hazard ratio, 2.77 [95% CI, 1.85 to 4.16]; P < 0.001) and SPECT (hazard ratio, 1.62 [CI, 1.11 to 2.38; P = 0.014) were both strong and independent predictors of MACE. Only CMR remained a significant predictor after adjustment for other cardiovascular risk factors, angiography result, or stratification for initial patient treatment. LIMITATION: Data are from a single-center observational study (albeit conducted in a high-volume institution for both CMR and SPECT). CONCLUSION: Five-year follow-up of the CE-MARC study indicates that compared with SPECT, CMR is a stronger predictor of risk for MACEs, independent of cardiovascular risk factors, angiography result, or initial patient treatment. This further supports the role of CMR as an alternative to SPECT for the diagnosis and management of patients with suspected CHD. PRIMARY FUNDING SOURCE: British Heart Foundation.

The incremental impact of cardiac MRI on clinical decision-making.

OBJECTIVE: Despite a significant expansion in the use of cardiac MRI (CMR), there is inadequate evaluation of its incremental impact on clinical decision-making over and above other well-established modalities. We sought to determine the incremental utility of CMR in routine practice. METHODS: 629 consecutive CMR studies referred by 44 clinicians from 9 institutions were evaluated. Pre-defined algorithms were used to determine the incremental influence on diagnostic thinking, influence on clinical management and thus the overall clinical utility. Studies were also subdivided and evaluated according to the indication for CMR. RESULTS: CMR provided incremental information to the clinician in 85% of cases, with incremental influence on diagnostic thinking in 85% of cases and incremental impact on management in 42% of cases. The overall incremental utility of CMR exceeded 90% in 7 out of the 13 indications, whereas in settings such as the evaluation of unexplained ventricular arrhythmia or mild left ventricular systolic dysfunction, this was <50%. CONCLUSION: CMR was frequently able to inform and influence decision-making in routine clinical practice, even with analyses that accepted only incremental clinical information and excluded a redundant duplication of imaging. Significant variations in yield were noted according to the indication for CMR. These data support a wider integration of CMR services into cardiac imaging departments. ADVANCES IN KNOWLEDGE: These data are the first to objectively evaluate the incremental value of a UK CMR service in clinical decision-making. Such data are essential when seeking justification for a CMR service.

Factors associated with false-negative cardiovascular magnetic resonance perfusion studies: A Clinical evaluation of magnetic resonance imaging in coronary artery disease (CE-MARC) substudy.

PURPOSE: To examine factors associated with false-negative cardiovascular magnetic resonance (MR) perfusion studies within the large prospective Clinical Evaluation of MR imaging in Coronary artery disease (CE-MARC) study population. Myocardial perfusion MR has excellent diagnostic accuracy to detect coronary heart disease (CHD). However, causes of false-negative MR perfusion studies are not well understood. MATERIALS AND METHODS: CE-MARC prospectively recruited patients with suspected CHD and mandated MR, myocardial perfusion scintigraphy, and invasive angiography. This subanalysis identified all patients with significant coronary stenosis by quantitative coronary angiography (QCA) and MR perfusion (1.5T, T1 -weighted gradient echo), using the original blinded image read. We explored patient and imaging characteristics related to false-negative or true-positive MR perfusion results, with reference to QCA. Multivariate regression analysis assessed the likelihood of false-negative MR perfusion according to four characteristics: poor image quality, triple-vessel disease, inadequate hemodynamic response to adenosine, and Duke jeopardy score (angiographic myocardium-at-risk score). RESULTS: In all, 265 (39%) patients had significant angiographic disease (mean age 62, 79% male). Thirty-five (5%) had false-negative and 230 (34%) true-positive MR perfusion. Poor MR perfusion image quality, triple-vessel disease, and inadequate hemodynamic response were similar between false-negative and true-positive groups (odds ratio, OR [95% confidence interval, CI]: 4.1 (0.82-21.0), P = 0.09; 1.2 (0.20-7.1), P = 0.85, and 1.6 (0.65-3.8), P = 0.31, respectively). Mean Duke jeopardy score was significantly lower in the false-negative group (2.6 ± 1.7 vs. 5.4 ± 3.0, OR 0.34 (0.21-0.53), P < 0.0001). CONCLUSION: False-negative cardiovascular MR perfusion studies are uncommon, and more common in patients with lower angiographic myocardium-at-risk. In CE-MARC, poor image quality, triple-vessel disease, and inadequate hemodynamic response were not significantly associated with false-negative MR perfusion.

Individual component analysis of the multi-parametric cardiovascular magnetic resonance protocol in the CE-MARC trial.

BACKGROUND: The CE-MARC study assessed the diagnostic performance investigated the use of cardiovascular magnetic resonance (CMR) in patients with suspected coronary artery disease (CAD). The study used a multi-parametric CMR protocol assessing 4 components: i) left ventricular function; ii) myocardial perfusion; iii) viability (late gadolinium enhancement (LGE)) and iv) coronary magnetic resonance angiography (MRA). In this pre-specified CE-MARC sub-study we assessed the diagnostic accuracy of the individual CMR components and their combinations. METHODS: All patients from the CE-MARC population (n = 752) were included using data from the original blinded-read. The four individual core components of the CMR protocol was determined separately and then in paired and triplet combinations. Results were then compared to the full multi-parametric protocol. RESULTS: CMR and X-ray angiography results were available in 676 patients. The maximum sensitivity for the detection of significant CAD by CMR was achieved when all four components were used (86.5%). Specificity of perfusion (91.8%), function (93.7%) and LGE (95.8%) on its own was significantly better than specificity of the multi-parametric protocol (83.4%) (all P < 0.0001) but with the penalty of decreased sensitivity (86.5% vs. 76.9%, 47.4% and 40.8% respectively). The full multi-parametric protocol was the optimum to rule-out significant CAD (Likelihood Ratio negative (LR-) 0.16) and the LGE component alone was the best to rue-in CAD (LR+ 9.81). Overall diagnostic accuracy was similar with the full multi-parametric protocol (85.9%) compared to paired and triplet combinations. The use of coronary MRA within the full multi-parametric protocol had no additional diagnostic benefit compared to the perfusion/function/LGE combination (overall accuracy 84.6% vs. 84.2% (P = 0.5316); LR- 0.16 vs. 0.21; LR+ 5.21 vs. 5.77). CONCLUSIONS: From this pre-specified sub-analysis of the CE-MARC study, the full multi-parametric protocol had the highest sensitivity and was the optimal approach to rule-out significant CAD. The LGE component alone was the optimal rule-in strategy. Finally the inclusion of coronary MRA provided no additional benefit when compared to the combination of perfusion/function/LGE. TRIAL REGISTRATION: Current Controlled Trials ISRCTN77246133.

Assessment of ischaemic burden in angiographic three-vessel coronary artery disease with high-resolution myocardial perfusion cardiovascular magnetic resonance imaging.

AIMS: This study compared the myocardial ischaemic burden (MIB) in patients with angiographic three-vessel coronary artery disease (3VD) using high-resolution and standard-resolution myocardial perfusion cardiovascular magnetic resonance (perfusion CMR) imaging. METHODS AND RESULTS: One hundred and five patients undergoing coronary angiography had two separate stress/rest perfusion CMR studies, one with standard-resolution (2.5 mm in-plane) and another with high-resolution (1.6 mm in-plane). Quantitative coronary angiography was used to define patients with angiographic 3VD. Perfusion CMR images were anonymized, randomly ordered and visually reported by two observers acting in consensus and blinded to all clinical and angiographic data. Perfusion was graded in each segment on a four-point scale and summed to produce a perfusion score and estimate of MIB for each patient. In patients with angiographic 3VD (n = 35), high-resolution acquisition identified more abnormal segments (7.2 ± 3.8 vs. 5.3 ± 4.0; P = 0.004) and territories (2.4 ± 0.9 vs. 1.6 ± 1.1; P = 0.002) and a higher overall perfusion score (20.1 ± 7.7 vs. 11.9 ± 9.4; P < 0.0001) per patient compared with standard-resolution. The number of segments with subendocardial ischaemia was greater with high-resolution acquisition (195 vs. 101; P < 0.0001). Hypoperfusion in all three territories was identified in 57% of 3VD patients by high-resolution compared with only 29% by standard-resolution (P = 0.04). The area-under-the-curve (AUC) for detecting angiographic 3VD using the estimated MIB was significantly greater with high-resolution than standard-resolution acquisition (AUC = 0.90 vs. 0.69; P < 0.0001). CONCLUSION: In patients with angiographic 3VD, the ischaemic burden detected by perfusion CMR is greater with high-resolution acquisition due to better detection of subendocardial ischaemia. High-resolution perfusion CMR may therefore be preferred for risk stratification and management of this high-risk patient group.

Comparison of cardiovascular magnetic resonance and single-photon emission computed tomography in women with suspected coronary artery disease from the Clinical Evaluation of Magnetic Resonance Imaging in Coronary Heart Disease (CE-MARC) Trial.

BACKGROUND: Coronary artery disease is the leading cause of death in women, and underdiagnosis contributes to the high mortality. This study compared the sex-specific diagnostic performance of cardiovascular magnetic resonance (CMR) and single-photon emission computed tomography (SPECT). METHODS AND RESULTS: A total of 235 women and 393 men with suspected angina underwent CMR, SPECT, and x-ray angiography as part of the Clinical Evaluation of Magnetic Resonance Imaging in Coronary Heart Disease (CE-MARC) study. CMR comprised adenosine stress/rest perfusion, cine imaging, late gadolinium enhancement, and magnetic resonance coronary angiography. Gated adenosine stress/rest SPECT was performed with (99m)Tc-tetrofosmin. For CMR, the sensitivity in women and men was similar (88.7% versus 85.6%; P=0.57), as was the specificity (83.5% versus 82.8%; P=0.86). For SPECT, the sensitivity was significantly worse in women than in men (50.9% versus 70.8%; P=0.007), but the specificities were similar (84.1% versus 81.3%; P=0.48). The sensitivity in both the female and male groups was significantly higher with CMR than SPECT (P<0.0001 for both), but the specificity was similar (P=0.77 and P=1.00, respectively). For perfusion-only components, CMR outperformed SPECT in women (area under the curve, 0.90 versus 0.67; P<0.0001) and in men (area under the curve, 0.89 versus 0.74; P<0.0001). Diagnostic accuracy was similar in both sexes with perfusion CMR (P=1.00) but was significantly worse in women with SPECT (P<0.0001). CONCLUSIONS: In both sexes, CMR has greater sensitivity than SPECT. Unlike SPECT, there are no significant sex differences in the diagnostic performance of CMR. These findings, plus an absence of ionizing radiation exposure, mean that CMR should be more widely adopted in women with suspected coronary artery disease. CLINICAL TRIAL REGISTRATION URL: http://www.controlled-trials.com. Unique identifier: ISRCTN77246133.

Reproducibility of first-pass cardiovascular magnetic resonance myocardial perfusion.

PURPOSE: To assess the reproducibility of semiquantitative and quantitative analysis of first-pass myocardial perfusion cardiovascular magnetic resonance (CMR) in healthy volunteers. MATERIALS AND METHODS: Eleven volunteers underwent myocardial perfusion CMR during adenosine stress and rest on 2 separate days. Perfusion data were acquired in a single mid-ventricular section in two cardiac phases to permit cardiac phase reproducibility comparisons. Semiquantitative analysis was performed to derive normalized upslopes of myocardial signal intensity profiles (myocardial perfusion index, MPI). The quantitative analysis estimated absolute myocardial blood flow (MBF) using Fermi-constrained deconvolution. The perfusion reserve index was calculated by dividing stress by rest data. Two observers performed all the measurements independently. One observer repeated all first scan measurements 4 weeks later. RESULTS: The reproducibility of perfusion CMR was highest for semiquantitative analysis with an intraobserver coefficient of variability (CoV) of 3%-7% and interobserver CoV of 4%-10%. Semiquantitative interstudy comparison was less reproducible (CoV of 13%-27%). Quantitative intraobserver CoV of 10%-18%, interobserver CoV of 8%-15% and interstudy CoV of 20%-41%. Reproducibility of systolic and diastolic phases and the endocardial and epicardial myocardial layer showed similar reproducibility on both semiquantitative and quantitative analysis. CONCLUSION: The reproducibility of CMR myocardial perfusion estimates is good, but varies between intraobserver, interobserver, and interstudy comparisons. In this study semiquantitative analysis was more reproducible than quantitative analysis.

High-resolution versus standard-resolution cardiovascular MR myocardial perfusion imaging for the detection of coronary artery disease.

BACKGROUND: Although accelerated high-spatial-resolution cardiovascular MR (CMR) myocardial perfusion imaging has been shown to be clinically feasible, there has not yet been a direct comparison with standard-resolution methods. We hypothesized that higher spatial resolution detects more subendocardial ischemia and leads to greater diagnostic accuracy for the detection coronary artery disease. This study compared the diagnostic accuracy of high-resolution and standard-resolution CMR myocardial perfusion imaging in patients with suspected coronary artery disease. METHODS AND RESULTS: A total of 111 patients were recruited to undergo 2 separate perfusion-CMR studies at 1.5 T, 1 with standard-resolution (2.5×2.5 mm in-plane) and 1 with high-resolution (1.6×1.6 mm in-plane) acquisition. High-resolution acquisition was facilitated by 8-fold k-t broad linear speed-up technique acceleration. Two observers visually graded perfusion in each myocardial segment on a 4-point scale. Segmental scores were summed to produce a perfusion score for each patient. All patients underwent invasive coronary angiography and coronary artery disease was defined as stenosis ≥50% luminal diameter (quantitative coronary angiography). CMR data were successfully obtained in 100 patients. In patients with coronary artery disease (n=70), more segments were determined to have subendocardial ischemia with high-resolution than with standard-resolution acquisition (279 versus 108; P<0.001). High-resolution acquisition had a greater diagnostic accuracy than standard resolution for identifying single-vessel disease (area under the curve, 0.88 versus 0.73; P<0.001) or multivessel disease (area under the curve, 0.98 versus 0.91; P=0.002) and overall (area under the curve, 0.93 versus 0.83; P<0.001). CONCLUSIONS: High-resolution perfusion-CMR has greater overall diagnostic accuracy than standard-resolution acquisition for the detection of coronary artery disease in both single- and multivessel disease and detects more subendocardial ischemia.

Cardiovascular magnetic resonance and single-photon emission computed tomography for diagnosis of coronary heart disease (CE-MARC): a prospective trial.

BACKGROUND: In patients with suspected coronary heart disease, single-photon emission computed tomography (SPECT) is the most widely used test for the assessment of myocardial ischaemia, but its diagnostic accuracy is reported to be variable and it exposes patients to ionising radiation. The aim of this study was to establish the diagnostic accuracy of a multiparametric cardiovascular magnetic resonance (CMR) protocol with x-ray coronary angiography as the reference standard, and to compare CMR with SPECT, in patients with suspected coronary heart disease. METHODS: In this prospective trial patients with suspected angina pectoris and at least one cardiovascular risk factor were scheduled for CMR, SPECT, and invasive x-ray coronary angiography. CMR consisted of rest and adenosine stress perfusion, cine imaging, late gadolinium enhancement, and MR coronary angiography. Gated adenosine stress and rest SPECT used (99m)Tc tetrofosmin. The primary outcome was diagnostic accuracy of CMR. This trial is registered at controlled-trials.com, number ISRCTN77246133. FINDINGS: In the 752 recruited patients, 39% had significant CHD as identified by x-ray angiography. For multiparametric CMR the sensitivity was 86·5% (95% CI 81·8-90·1), specificity 83·4% (79·5-86·7), positive predictive value 77·2%, (72·1-81·6) and negative predictive value 90·5% (87·1-93·0). The sensitivity of SPECT was 66·5% (95% CI 60·4-72·1), specificity 82·6% (78·5-86·1), positive predictive value 71·4% (65·3-76·9), and negative predictive value 79·1% (74·8-82·8). The sensitivity and negative predictive value of CMR and SPECT differed significantly (p<0·0001 for both) but specificity and positive predictive value did not (p=0·916 and p=0·061, respectively). INTERPRETATION: CE-MARC is the largest, prospective, real world evaluation of CMR and has established CMR's high diagnostic accuracy in coronary heart disease and CMR's superiority over SPECT. It should be adopted more widely than at present for the investigation of coronary heart disease. FUNDING: British Heart Foundation.

Endocardial and epicardial myocardial perfusion determined by semi-quantitative and quantitative myocardial perfusion magnetic resonance.

This study aims to quantify subendocardial and subepicardial myocardial blood flow (MBF) from dynamic contrast-enhanced MRI and to compare semi-quantitative and quantitative analysis methods. 17 healthy volunteers (9 males, mean age 34 ± 8) were scanned during adenosine stress and at rest. A "semi-quantitative" myocardial perfusion index (MPI) was calculated based on maximal upslopes of signal intensity-time profiles for a mid-ventricular myocardial slice. In addition, absolute MBF (ml/g/min) was estimated using Fermi-constrained deconvolution. On semi-quantitative analysis, the ratio of subendocardial to subepicardial MPI was 0.98 ± 0.1 at stress and 1.16 ± 0.09 at rest, P < 0.0001. The MPRI (i.e. the ratio of stress over rest MPI) for the subendocardium was 1.54 ± 0.3 versus 1.81 ± 0.35 for the subepicardium, P = 0.03. For quantitative analysis, the ratio of subendocardial to subepicardial MBF was 0.91 ± 0.11 at stress versus 1.17 ± 0.16 at rest, P < 0.0001. The subendocardial MBF reserve was also lower than in the subepicardium (2.6 ± 0.75 vs. 3.32 ± 0.93, P = 0.027). In conclusion, semi-quantitative and quantitative analysis of dynamic contrast-enhanced MRI shows higher subendocardial blood flow at rest and reduced subendocardial perfusion reserve compared to the subepicardium.

3D Echo systematically underestimates right ventricular volumes compared to cardiovascular magnetic resonance in adult congenital heart disease patients with moderate or severe RV dilatation.

BACKGROUND: Three dimensional echo is a relatively new technique which may offer a rapid alternative for the examination of the right heart. However its role in patients with non-standard ventricular size or anatomy is unclear. This study compared volumetric measurements of the right ventricle in 25 patients with adult congenital heart disease using both cardiovascular magnetic resonance (CMR) and three dimensional echocardiography. METHODS: Patients were grouped by diagnosis into those expected to have normal or near-normal RV size (patients with repaired coarctation of the aorta) and patients expected to have moderate or worse RV enlargement (patients with repaired tetralogy of Fallot or transposition of the great arteries). Right ventricular end diastolic volume, end systolic volume and ejection fraction were compared using both methods with CMR regarded as the reference standard RESULTS: Bland-Altman analysis of the 25 patients demonstrated that for both RV EDV and RV ESV, there was a significant and systematic under-estimation of volume by 3D echo compared to CMR. This bias led to a mean underestimation of RV EDV by -34% (95%CI: -91% to + 23%). The degree of underestimation was more marked for RV ESV with a bias of -42% (95%CI: -117% to + 32%). There was also a tendency to overestimate RV EF by 3D echo with a bias of approximately 13% (95% CI -52% to +27%). CONCLUSIONS: Statistically significant and clinically meaningful differences in volumetric measurements were observed between the two techniques. Three dimensional echocardiography does not appear ready for routine clinical use in RV assessment in congenital heart disease patients with more than mild RV dilatation at the current time.

Effect of improving spatial or temporal resolution on image quality and quantitative perfusion assessment with k-t SENSE acceleration in first-pass CMR myocardial perfusion imaging.

k-t Sensitivity-encoded (k-t SENSE) acceleration has been used to improve spatial resolution, temporal resolution, and slice coverage in first-pass cardiac magnetic resonance myocardial perfusion imaging. This study compares the effect of investing the speed-up afforded by k-t SENSE acceleration in spatial or temporal resolution. Ten healthy volunteers underwent adenosine stress myocardial perfusion imaging using four saturation-recovery gradient echo perfusion sequences: a reference sequence accelerated by sensitivity encoding (SENSE), and three k-t SENSE-accelerated sequences with higher spatial resolution ("k-t High"), shorter acquisition window ("k-t Fast"), or a shared increase in both parameters ("k-t Hybrid") relative to the reference. Dark-rim artifacts and image quality were analyzed. Semiquantitative myocardial perfusion reserve index (MPRI) and Fermi-derived quantitative MPR were also calculated. The k-t Hybrid sequence produced highest image quality scores at rest (P = 0.015). Rim artifact thickness and extent were lowest using k-t High and k-t Hybrid sequences (P < 0.001). There were no significant differences in MPRI and MPR values derived by each sequence. Maximizing spatial resolution by k-t SENSE acceleration produces the greatest reduction in dark rim artifact. There is good agreement between k-t SENSE and standard acquisition methods for semiquantitative and fully quantitative myocardial perfusion analysis.

Clinical evaluation of magnetic resonance imaging in coronary heart disease: the CE-MARC study.

BACKGROUND: Several investigations are currently available to establish the diagnosis of coronary heart disease (CHD). Of these, cardiovascular magnetic resonance (CMR) offers the greatest information from a single test, allowing the assessment of myocardial function, perfusion, viability and coronary artery anatomy. However, data from large scale studies that prospectively evaluate the diagnostic accuracy of multi-parametric CMR for the detection of CHD in unselected populations are lacking, and there are few data on the performance of CMR compared with current diagnostic tests, its prognostic value and cost-effectiveness. METHODS/DESIGN: This is a prospective diagnostic accuracy cohort study of 750 patients referred to a cardiologist with suspected CHD. Exercise tolerance testing (ETT) will be preformed if patients are physically able. Recruited patients will then undergo CMR and single photon emission tomography (SPECT) followed in all patients by invasive X-ray coronary angiography. The order of the CMR and SPECT tests will be randomised. The CMR study will comprise rest and adenosine stress perfusion, cine imaging, late gadolinium enhancement and whole-heart MR coronary angiography. SPECT will use a gated stress/rest protocol. The primary objective of the study is to determine the diagnostic accuracy of CMR in detecting significant coronary stenosis, as defined by X-ray coronary angiography. Secondary objectives include an assessment of the prognostic value of CMR imaging, a comparison of its diagnostic accuracy against SPECT and ETT, and an assessment of cost-effectiveness. DISCUSSION: The CE-MARC study is a prospective, diagnostic accuracy cohort study of 750 patients assessing the performance of a multi-parametric CMR study in detecting CHD using invasive X-ray coronary angiography as the reference standard and comparing it with ETT and SPECT. TRIAL REGISTRATION: Current Controlled Trials ISRCTN77246133.