Cosima Jahnke

Prognostic Value of Cardiac Magnetic Resonance Stress Tests Adenosine Stress Perfusion and Dobutamine Stress Wall Motion Imaging

Background— Adenosine stress magnetic resonance perfusion (MRP) and dobutamine stress magnetic resonance (DSMR) wall motion analyses are highly accurate for the detection of myocardial ischemia. However, knowledge about the prognostic value of stress MR examinations is limited. We sought to determine the value of MRP and DSMR, as assessed during a single-session examination, in predicting the outcome of patients with known or suspected coronary artery disease. Methods and Results— In 513 patients (with known or suspected coronary disease, prior coronary artery bypass graft, or percutaneous coronary intervention), a combined single-session magnetic resonance stress examination (MRP and DSMR) was performed at 1.5 T. For first-pass perfusion imaging, the standard adenosine stress imaging protocol (140 &mgr;g · kg−1 · min−1 for 6 minutes, 3-slice turbo field echo-echo-planar imaging or steady-state free precession sequence, 0.05 mmol/kg Gd-DTPA) was applied, and for DSMR, the standard high-dose dobutamine/atropine protocol (steady-state free-precession cine sequence) was applied. Stress testing was classified as pathological if at MRP ≥1 segment showed an inducible perfusion deficit >25% transmurality or if at DSMR ≥1 segment showed an inducible wall motion abnormality. During a median follow-up of 2.3 years (range, 0.06 to 4.55 years), 19 cardiac events occurred (4.1%; 9 cardiac deaths, 10 nonfatal myocardial infarctions). The 3-year event-free survival was 99.2% for patients with normal MRP and DSMR and 83.5% for those with abnormal MRP and DSMR. Univariate analysis showed ischemia identified by MRP and DSMR to be predictive of cardiac events (hazard ratio, 12.51; 95% confidence interval, 3.64 to 43.03; and hazard ratio, 5.42; 95% confidence interval, 2.18 to 13.50; P<0.001, respectively); other predictors were diabetes mellitus, known coronary artery disease, and the presence of resting wall motion abnormality. By multivariate analysis, ischemia on magnetic resonance stress testing (MRP or DSMR) was an independent predictor of cardiac events. In a stepwise multivariate model (Cox regression), an abnormal magnetic resonance stress test result had significant incremental value over clinical risk factors and resting wall motion abnormality (P<0.001). Conclusions— In patients with known or suspected coronary artery disease, myocardial ischemia detected by MRP and DSMR can be used to identify patients at high risk for subsequent cardiac death or nonfatal myocardial infarction. For patients with normal MRP and DSMR, the 3-year event-free survival was 99.2%. MR stress testing provides important incremental information over clinical risk factors and resting wall motion abnormalities.

Comparison of Dobutamine Stress Magnetic Resonance, Adenosine Stress Magnetic Resonance, and Adenosine Stress Magnetic Resonance Perfusion

Background—Dobutamine stress MR (DSMR) is highly accurate for the detection of inducible wall motion abnormalities (IWMAs). Adenosine has a more favorable safety profile and is well established for the assessment of myocardial perfusion. We evaluated the diagnostic value of IWMAs during dobutamine and adenosine stress MR and adenosine MR perfusion compared with invasive coronary angiography. Methods and Results—Seventy-nine consecutive patients (suspected or known coronary disease, no history of prior myocardial infarction) scheduled for cardiac catheterization underwent cardiac MR (1.5 T). After 4 minutes of adenosine infusion (140 &mgr;g · kg−1 · min−1 for 6 minutes), wall motion was assessed (steady-state free precession), and subsequently perfusion scans (3-slice turbo field echo-echo planar imaging; 0.05 mmol/kg Gd-BOPTA) were performed. After a 15-minute break, rest perfusion was imaged, followed by standard DSMR/atropine stress MR. Wall motion was classified as pathological if ≥1 segment showed IWMAs. The transmural extent of inducible perfusion deficits (<25%, 25% to 50%, 51% to 75%, and >75%) was used to grade segmental perfusion. Quantitative coronary angiography was performed with significant stenosis defined as >50% diameter stenosis. Fifty-three patients (67%) had coronary artery stenoses >50%; sensitivity and specificity for detection by dobutamine and adenosine stress and adenosine perfusion were 89% and 80%, 40% and 96%, and 91% and 62%, respectively. Adenosine IWMAs were seen only in segments with >75% transmural perfusion deficit. Conclusions—DSMR is superior to adenosine stress for the induction of IWMAs in patients with significant coronary artery disease. Visual assessment of adenosine stress perfusion is sensitive with a low specificity, whereas adenosine stress MR wall motion is highly specific because it identifies only patients with high-grade perfusion deficits. Thus, DSMR is the method of choice for current state-of-the-art treatment regimens to detect ischemia in patients with suspected or known coronary artery disease but no history of prior myocardial infarction.

Whole-heart dynamic three-dimensional magnetic resonance perfusion imaging for the detection of coronary artery disease defined by fractional flow reserve: determination of volumetric myocardial ischaemic burden and coronary lesion location

AIMS Dynamic three-dimensional-cardiac magnetic resonance (3D-CMR) perfusion proved highly diagnostic for the detection of angiographically defined coronary artery disease (CAD) and has been used to assess the efficacy of coronary stenting procedures. The present study aimed to relate significant coronary lesions as assessed by fractional flow reserve (FFR) to the volume of myocardial hypoenhancement on 3D-CMR adenosine stress perfusion imaging and to define the inter-study reproducibility of stress inducible 3D-CMR hypoperfusion. METHODS AND RESULTS A total of 120 patients with known or suspected CAD were examined in two CMR centres using 1.5 T systems. The protocol included cine imaging, 3D-CMR perfusion during adenosine infusion, and at rest followed by delayed enhancement (DE) imaging. Fractional flow reserve was recorded in epicardial coronary arteries and side branches with ≥2 mm luminal diameter and >40% severity stenosis (pathologic FFR < 0.75). Twenty-five patients underwent an identical repeat CMR examination for the determination of inter-study reproducibility of 3D-CMR perfusion deficits induced by adenosine. Three-dimensional CMR perfusion scans were visually classified as pathologic if one or more segments showed an inducible perfusion deficit in the absence of DE. Myocardial ischaemic burden (MIB) was measured by segmentation of the area of inducible hypoenhancement and normalized to left ventricular myocardial volume (MIB, %). Three-dimensional CMR perfusion resulted in a sensitivity, specificity, and diagnostic accuracy of 90, 82, and 87%, respectively. Substantial concordance was found for inter-study reproducibility [Lins correlation coefficient: 0.98 (95% confidence interval: 0.96-0.99)]. CONCLUSION Three-dimensional CMR stress perfusion provided high diagnostic accuracy for the detection of functionally significant CAD. Myocardial ischaemic burden measurements were highly reproducible and allowed the assessment of CAD severity.

Diagnostic Performance of Myocardial Perfusion MR at 3 T in Patients with Coronary Artery Disease

PURPOSE To prospectively determine the diagnostic performance of myocardial perfusion magnetic resonance (MR) imaging at 3 T for helping depict clinically relevant coronary artery stenosis (> or =50% diameter) in patients with suspected or known coronary artery disease (CAD), with coronary angiography as the reference standard. MATERIALS AND METHODS The study was approved by the local ethics committee; written informed consent was obtained. Vasodilator stress perfusion imaging by using a turbo field-echo sequence was obtained in 101 patients (71 men, 30 women; mean age, 62 years +/- 7.7 [standard deviation]) scheduled for coronary angiography. Myocardial ischemia was defined as stress-inducible perfusion deficit in arterial territories without delayed enhancement (DE) or additional stress-inducible perfusion deficit in territories with nontransmural DE. Images were evaluated in consensus by two blinded readers. Diagnostic performance was determined on per-patient and per-coronary artery territory bases. The number of dark rim artifacts in patients without DE was determined in a second read. Interobserver variability was assessed in 40 randomly selected patients. RESULTS One hundred one patients underwent MR examinations. Coronary angiography depicted relevant stenosis in 70 (69%) patients. Patient-based sensitivity and specificity were 90% and 71%, respectively. Sensitivity, specificity, and diagnostic accuracy for the detection of coronary stenosis in a specific territory were 76%, 89%, and 86%, respectively. In 24% of patients without DE, dark rim artifacts were detected, mostly in the left anterior descending artery territory (56%). In 40 randomly selected patients, there was agreement in the determination of myocardial perfusion deficits in 37 (93%, kappa = 0.79) patients. CONCLUSION Myocardial perfusion MR imaging by using saturation-recovery spoiled gradient-echo imaging at 3 T has an accuracy of 84% for depicting hemodynamically relevant coronary artery stenosis in patients with suspected and known CAD.

Dynamic 3-Dimensional Stress Cardiac Magnetic Resonance Perfusion Imaging Detection of Coronary Artery Disease and Volumetry of Myocardial Hypoenhancement Before and After Coronary Stenting

OBJECTIVES The aim of this study was to establish a new, dynamic 3-dimensional cardiac magnetic resonance (3D-CMR) perfusion scan technique exploiting data correlation in k-space and time with sensitivity-encoding and to determine its value for the detection of coronary artery disease (CAD) and volumetry of myocardial hypoenhancement (VOLUME(hypo)) before and after percutaneous coronary stenting. BACKGROUND Dynamic 3D-CMR perfusion imaging might improve detection of myocardial perfusion deficits and could facilitate direct volumetry of myocardial hypoenhancement. METHODS In 146 patients with known or suspected CAD, a 3.0-T CMR examination was performed including cine imaging, 3D-CMR perfusion under adenosine stress and at rest followed by delayed enhancement imaging. Quantitative invasive coronary angiography defined significant CAD (≥ 50% luminal narrowing). Forty-eight patients underwent an identical repeat CMR examination after percutaneous stenting of at least 1 coronary lesion. The 3D-CMR perfusion scans were visually classified as pathologic if ≥ 1 segment showed an inducible perfusion deficit in the absence of delayed enhancement. The VOLUME(hypo) was measured by segmentation of the area of inducible hypoenhancement and normalized to left-ventricular myocardial volume (%VOLUME(hypo)). RESULTS The 3D-CMR perfusion resulted in a sensitivity, specificity, and diagnostic accuracy of 91.7%, 74.3%, and 82.9%, respectively. Before and after coronary stenting, %VOLUME(hypo) averaged to 14.2 ± 9.5% and 3.2 ± 5.2%, respectively, with a relative VOLUME(hypo) reduction of 79.4 ± 25.4%. Intrareader and inter-reader reproducibility of VOLUME(hypo) measurements was high (Lins concordance correlation coefficient, 0.96 and 0.96, respectively). CONCLUSIONS The 3D-CMR stress perfusion provided high image quality and high diagnostic accuracy for the detection of significant CAD. The VOLUME(hypo) measurements were highly reproducible and allowed for the assessment of the treatment effect achievable by percutaneous coronary stenting.

Additional Value of Myocardial Perfusion Imaging During Dobutamine Stress Magnetic Resonance for the Assessment of Coronary Artery Disease

Background—Dobutamine stress magnetic resonance (DSMR) imaging has emerged as a valuable tool for the detection of inducible wall motion abnormalities. The role of perfusion imaging during DSMR is not well defined. We examined whether the addition of myocardial perfusion imaging during DSMR provides incremental benefit for the evaluation of coronary artery disease. Methods and Results—DSMR was combined with perfusion imaging in 455 consecutive patients who were scheduled for clinically indicated invasive coronary angiography. Perfusion images were acquired in 3 standard short-views at rest and during maximum dobutamine-atropine stress. Wall motion and perfusion images were interpreted sequentially, blinded to other data. Significant (≥70%) stenoses were present in 285 patients on invasive coronary angiography. The use of DSMR combined with perfusion imaging versus DSMR increased sensitivity (91% versus 85%, P=0.001), but not specificity (70% versus 82%, P=0.001), resulting in identical overall diagnostic accuracy (84% versus 84%, P=NS; Youden index 0.61 versus 0.67). DSMR combined with perfusion imaging enabled the correct diagnosis of coronary artery disease in an additional 13% of DSMR-negative patients at the cost of 11% more false-positive cases. Conclusion—The addition of perfusion imaging during DSMR improves sensitivity for the diagnosis of coronary artery disease but does not enhance overall diagnostic accuracy because of a concomitant decrease in specificity.

Long-Term Prognostic Value of Dobutamine Stress CMR

OBJECTIVES The aim of this study was to assess the long-term value of high-dose dobutamine cardiac magnetic resonance (DCMR) for the prediction of cardiac events in a large cohort of patients with known or suspected coronary artery disease. BACKGROUND High-dose DCMR has been shown to be a useful technique for diagnosis and intermediate-term prognostic stratification. METHODS Clinical data and DCMR results were analyzed in 1,463 consecutive patients undergoing DCMR between 2000 and 2004. Ninety-four patients were lost to follow-up. The remaining 1,369 patients were followed up for a mean of 44 ± 24 months. Cardiac events, defined as cardiac death and nonfatal myocardial infarction, were related to clinical and DCMR results. RESULTS Three-hundred fifty-two patients underwent early revascularization (≤ 3 months of DCMR) and were excluded from analysis. Of the remaining 1,017 patients, 301 patients (29.6%) experienced inducible wall motion abnormalities (WMA). Forty-six cardiac events were reported. In those with and without inducible WMA, the proportion of patients with cardiac events was 8.0% versus 3.1%, respectively, p = 0.001 (hazard ratio: 3.3; 95% confidence interval: 1.8 to 5.9 for the presence of inducible WMA; p < 0.001). A DCMR without inducible WMA carried an excellent prognosis, with a 6-year cardiac event-free survival of 96.8%. In all 1,369 patients in the patient group with stress-inducible WMA, those patients with medical therapy demonstrated a trend to a higher cardiac event rate (8.0%) than those with early revascularization (5.4%) (p = 0.234). Patients with normal DCMR and medical therapy or early revascularization demonstrated similar cumulative cardiac event rates (3.1% vs. 3.2%, p = 0.964). CONCLUSIONS In a large cohort of patients, DCMR has an added value for predicting cardiac events during long-term follow-up, improving the differentiation between high-risk and low-risk patients. Patients with inducible WMA and following early revascularization, demonstrate lower cardiac event rates than patients with medical therapy alone.

Four-dimensional single breathhold magnetic resonance imaging using kt-BLAST enables reliable assessment of left- and right-ventricular volumes and mass

To prospectively determine the accuracy of four‐dimensional (4D) kt‐broad‐use linear acquisition speed‐up technique (BLAST) accelerated MRI (kt‐BLAST) for the assessment of left‐ventricular (LV) volumes and mass as well as right‐ventricular (RV) volumes in comparison to standard multiple breathhold cine imaging.

A New Approach for Rapid Assessment of the Cardiac Rest Period for Coronary MRA

BACKGROUND Effective suppression of cardiac motion is crucial for MR coronary angiography (MRCA). Thus, we evaluated a new technique for rapid and automatic detection of the cardiac rest period in comparison to the conventional visual assessment of the coronary artery rest periods. METHODS One hundred and thirty-five consecutive cardiac patients were examined (Philips Intera CV 1.5 T, Best, The Netherlands). Visual assessment of the left and right coronary rest periods was done using a cine-SSFP scan with a transversal slice orientation (retrospective gating, 40 phases/cardiac cycle); the coronary rest period was defined as the duration of the coronary artery being completely within a region of interest placed on the outer edge of the cross-section of the vessel. Common coronary rest period as determined from visual assessment was defined as the intersection of both coronary artery rest periods. For comparison, an automatic technique was applied: using the position of the shim volume to define a correlation kernel, the cross-correlations of consecutive cine images were registered and displayed in a graph. Based on these cross-correlation values, the cardiac rest period was detected. The correlation between the visual and automated analysis was assessed. RESULTS A high correlation between the automatically and visually determined starting points for the coronary artery rest periods and the cardiac rest period was found. The automatically assessed cardiac rest period was significantly shorter in comparison to the visually assessed left and right coronary artery rest period (103 +/- 46 ms vs. 158 +/- 72 ms and 117 +/- 52 ms, respectively; p < 0.001). However, the common coronary rest period demonstrated excellent agreement with the cardiac rest period (r = 0.93, p < 0.001) without a significant difference in duration (109 +/- 52 ms vs. 103 +/- 46 ms). CONCLUSIONS Automated analysis of the cardiac rest period yielded similar results compared to the visual analysis. This rapid assessment of a cardiac acquisition window may be most helpful for MRCA, especially when aiming at 3-dimensional coverage of the whole coronary arterial tree during a single scan.

Detection of coronary stenoses with contrast enhanced, three-dimensional free breathing coronary MR angiography using the gadolinium-based intravascular contrast agent gadocoletic acid (B-22956)

PURPOSE To determine the diagnostic value of the intravascular contrast agent gadocoletic acid (B-22956) in three-dimensional, free breathing coronary magnetic resonance angiography (MRA) for stenosis detection in patients with suspected or known coronary artery disease. METHODS Eighteen patients underwent three-dimensional, free breathing coronary MRA of the left and right coronary system before and after intravenous application of a single dose of gadocoletic acid (B-22956) using three different dose regimens (group A 0.050 mmol/kg; group B 0.075 mmol/kg; group C 0.100 mmol/kg). Precontrast scanning followed a coronary MRA standard non-contrast T2 preparation/turbo-gradient echo sequence (T2Prep); for postcontrast scanning an inversion-recovery gradient echo sequence was used (real-time navigator correction for both scans). In pre- and postcontrast scans quantitative analysis of coronary MRA data was performed to determine the number of visible side branches, vessel length and vessel sharpness of each of the three coronary arteries (LAD, LCX, RCA). The number of assessable coronary artery segments was determined to calculate sensitivity and specificity for detection of stenosis > or = 50% on a segment-to-segment basis (16-segment-model) in pre- and postcontrast scans with x-ray coronary angiography as the standard of reference. RESULTS Dose group B (0.075 mmol/kg) was preferable with regard to improvement of MR angiographic parameters: in postcontrast scans all MR angiographic parameters increased significantly except for the number of visible side branches of the left circumflex artery. In addition, assessability of coronary artery segments significantly improved postcontrast in this dose group (67 versus 88%, p < 0.01). Diagnostic performance (sensitivity, specificity, accuracy) was 83, 77 and 78% for precontrast and 86, 95 and 94% for postcontrast scans. CONCLUSIONS The use of gadocoletic acid (B-22956) results in an improvement of MR angiographic parameters, asssessability of coronary segments and detection of coronary stenoses > or = 50%.