Perfusion Cardiac Magnetic Resonance Research Articles

Value of Vasodilator Stress Myocardial Contrast Echocardiography and Magnetic Resonance Imaging for the Differential Diagnosis of Ischemic versus Nonischemic Cardiomyopathy

Noninvasive differentiation of ischemic versus nonischemic cardiomyopathy (CM) remains challenging because of the low specificity of imaging-based tests in these patients. We hypothesized that myocardial contrast echocardiography (MCE) and cardiac magnetic resonance (CMR), combined with vasodilator stress, could provide accurate alternatives for determining the cause of CM. To allow side-by-side comparisons between these techniques with coronary angiography as a reference, we studied 16 patients referred for coronary angiography after abnormal nuclear perfusion studies. Both MCE and CMR images were acquired within 48 hours with infusion of adenosine. MCE included flash-echo imaging during intravenous infusion of echocardiographic contrast solution. CMR included gadolinium injections for first-pass perfusion and delayed enhancement imaging. MCE and CMR images were reviewed by experienced investigators, blinded to the findings of the other modality and angiography. For each technique, each myocardial segment was classified as normal or abnormal. Sensitivity and specificity of each technique were calculated against the angiography reference. These calculations were also performed using a perfusion territory as a unit of analysis. Six of 16 patients had normal coronary arteries, and three patients had stenosis < 50%. By using this threshold for abnormal perfusion, segment-by-segment comparisons with angiography resulted in sensitivity of 0.88, 0.61, and 0.71 and specificity of 0.74, 0.86, and 0.94 for CMR perfusion, delayed enhancement scans, and MCE sequences, respectively. Using stenosis > 70% as a threshold resulted in a small decrease in both sensitivity and specificity (0.02-0.04) for all three techniques. Analysis of the ability of these techniques to detect an abnormality in at least one perfusion territory yielded sensitivity of 1.00, 1.00, and 0.86 and specificity of 0.78, 0.78, and 0.89, correspondingly, which were threshold-independent. Both CMR and MCE perfusion imaging may be used to differentiate between ischemic and nonischemic CM. These emerging diagnostic tools may prove useful in strategizing treatment in these patients and thus avoiding unnecessary invasive procedures.

Added Value of Rest to Stress Study for Recognition of Artifacts in Perfusion Cardiovascular Magnetic Resonance

The objective was to determine whether rest perfusion (RP) adds to stress perfusion (SP) and late gadolinium enhancement (LGE) cardiac magnetic resonance (CMR) for detection of impaired coronary flow reserve. We enrolled patients (n=45) referred for myocardial perfusion SPECT (MPS) for adenosine CMR stress. SP, RP and LGE images were obtained with 99mTc sestamibi injection during a single adenosine infusion. Segmental perfusion and confidence scores were recorded for SP-LGE interpreted with and without RP. CMR agreement with MPS was determined. MPS was normal in 653 and abnormal in 67 segments. SP-LGE CMR interpreted without RP was normal in 407, abnormal in 313 segments, and showed poor agreement with MPS (58%). Two hundred thirty-seven segments were changed to normal using data from RP, improving agreement (87%, p<0.0001). Reader confidence was low in 33 patients with SP-LGE and improved in 26 patients using SP-RP-LGE, where 37/45 were read with high confidence. Artifact was present in 68% of SP CMR and accounted for false positive studies. Agreement between single stress adenosine CMR and MPS is optimized by combining RP, LGE and SP CMR. Addition of RP CMR to SP-LGE CMR improved agreement with MPS and reader confidence. Improved CMR pulse sequences may change the role of rest perfusion data.

Quantitative Magnetic Resonance Perfusion Imaging Detects Anatomic and Physiologic Coronary Artery Disease as Measured by Coronary Angiography and Fractional Flow Reserve

To evaluate the ability of quantitative perfusion cardiac magnetic resonance (CMR) to assess the hemodynamic significance of coronary artery disease (CAD) compared with well-established anatomic and physiologic techniques. Fractional flow reserve (FFR) is considered by many investigators to be a reliable stenosis-specific method to determine hemodynamically significant CAD. Quantitative perfusion CMR is a promising noninvasive approach to detect CAD but has yet to be validated against FFR. This is a prospective study in patients with suspected CAD who underwent coronary angiography, FFR, and CMR assessments. The quantitative myocardial perfusion reserve (MPR) was calculated in 720 myocardial sectors (8 sectors/slice). The MPR was calculated from the ratio between stress and rest myocardial flow based on signal intensity time curves using deconvolution analysis. Stress was simulated with adenosine for both FFR and MPR. The MPR assessments were compared to FFR (n = 44 coronary segments) and quantitative coronary angiography (n = 108 segments) in the corresponding coronary territories. The MPR was 1.54 +/- 0.36 in segments with FFR < or =0.75 (n = 14) and 2.11 +/- 0.68 in those with FFR >0.75 (n = 30; p = 0.0054). An MPR cutoff of 2.04 was 92.9% (95% CI 77.9 to 100.0) sensitive and 56.7% (95% CI 32.8 to 80.6) specific in predicting a coronary segment with FFR < or =0.75. The MPR was 1.54 +/- 0.49 in coronary segments with > or =50% diameter stenosis (DS) (n = 47) and 2.13 +/- 0.80 in segments with <50% DS (n = 61; p < 0.001). An MPR cutoff of 2.04 was 85.1% (95% CI 71.1 to 99.2) sensitive and 49.2% (95% CI 33.6 to 64.8) specific in predicting CAD with > or =50% DS. Quantitative perfusion CMR is a safe noninvasive test that represents a stenosis-specific alternative to determine the hemodynamic significance of CAD.

Evaluation of cardiac magnetic resonance imaging parameters to detect anatomically and hemodynamically significant coronary artery disease

Cardiac magnetic resonance (cMR) perfusion imaging is a promising technique to assess coronary artery disease (CAD). Our objective was to evaluate accuracy of various cMR imaging parameters to detect significant CAD as compared with angiography or fractional flow reserve (FFR). We prospectively enrolled 37 patients who underwent coronary angiography, FFR, and cMR perfusion imaging. Semiquantitative assessments, namely maximum up-slope and peak-intensity indexes, were derived from time-intensity ratios between rest and stress. Myocardial perfusion reserve (MPR), calculated using Fermi deconvolution technique, was the quantitative cMR imaging parameter. Qualitative assessments were visually performed by independent analysts. Accuracy of quantitative, semiquantitative, and qualitative cMR imaging data was compared with quantitative coronary angiography in 108 segments and FFR in 44 segments. Sensitivity and specificity for hemodynamically significant CAD (FFR < or = 0.75) were 92.9% and 56.7%, respectively, for MPR (cutoff, 2.06). Area under the curve to detect FFR < or = 0.75 was 0.78 for MPR (P < .01), 0.63 for up-slope (P = NS), and 0.66 (P = NS) for peak intensity. Sensitivity and specificity for anatomically significant CAD (> 50% diameter stenosis [DS]) were 87.2% and 49.2%, respectively, for MPR (cutoff, 2.06). Area under the curve was 0.75 for MPR, 0.69 for up-slope, and 0.65 for peak intensity to detect > 50% DS (all P < .05). Visual assessment yielded sensitivity of 78.6% and specificity of 65.5% to predict FFR < or = 0.75 and sensitivity of 74.5% and specificity of 67.2% to predict > 50% DS. Myocardial perfusion reserve appears to be the most accurate index to detect anatomical and hemodynamically significant CAD. Standardization of such quantitative methods, with minimal operator dependency, would be useful for clinical and research applications.

Metastatic Extracavitary Cardiac Melanoma

Melanoma is a neoplasm notorious for its dismal prognosis and its propensity for cardiac involvement. Roughly a third of patients diagnosed with primary cutaneous melanoma develop pulmonary, osseous, cerebral or hepatic metastatic disease ante mortem. In contrast, ante mortem cardiac involvement is reported in 2% of cases but in over 50% of patients with metastatic melanoma postmortem.1 Cardiac involvement is usually multifocal, believed to disseminate hematogenously and commonly involves the epicardium, myocardium, pericardium or may present as intracavitary tumors.2 The surgical management of cardiac tumors can be challenging, particularly when they occur in locations that make surgical access and resection technically difficult. Recent refinements in myocardial perfusion imaging, computerized tomography, and cardiac magnetic resonance imaging help provide precise information on anatomic location, vascularity, and tumor extension into adjacent mediastinal structures.3 Early detection of cardiac melanoma has important therapeutic and prognostic …

Safety and diagnostic accuracy of stress cardiac magnetic resonance imaging vs exercise tolerance testing early after acute ST elevation myocardial infarction

Objective:To determine the safety and diagnostic accuracy of adenosine-stress cardiac magnetic resonance (CMR) perfusion imaging early after acute ST elevation myocardial infarction (STEMI) compared with standard exercise tolerance testing (ETT).Design...

Detection of cardiac small vessel disease by adenosine-stress magnetic resonance

Background Patients testing positive for myocardial ischemia but without significant coronary artery (CA) stenosis in coronary angiography (CXA) are characterized as having “small vessel disease” (SVD). The aim of our study was to identify these patients by stress perfusion cardiac magnetic resonance (CMR). Methods 317 patients with suspected myocardial ischemia and clinical indication for CXA were scanned < 72 h before CXA in a whole-body 1.5T scanner. After 3 min of adenosine infusion (140 μg/kg/min), a myocardial first-pass perfusion sequence in 4–5 contiguous short-axis orientations using a Gadolinium-based contrast agent (0.1 mmol/kg) was performed. Images were analyzed qualitatively by two independent and blinded investigators. Results Perfusion deficits were detected in 93% of our patients. In 78% of patients with relevant perfusion delay, perfusion deficits extended to > 1/3 of the wall thickness in ≥ 2 myocardial segments, persisted for > 5 heartbeats and were regarded as relevant coronary macroangiopathy. All of these patients had significant CA stenosis (60% had luminal narrowing > 70% and 18% had 50–70%). 22% of the patients had perfusion deficits affecting ≤ 1/3 of wall thickness with persistence for ≤ 5 heartbeats and were regarded as having SVD. None of these patients had a CA stenosis of > 50% or received CA revascularization. These patients more frequently had hypertension ( p < 0.0001), diabetes ( p < 0.05) and circumferential perfusion deficits ( p < 0.0001) than other patients. Conclusion Stress perfusion CMR allows non-invasive differentiation between patients with significant CA stenosis and patients with SVD caused by hypertension and/or diabetes based on the temporal and spatial extent of perfusion deficits. Patients with SVD more often have diffuse perfusion deficits with shorter persistence than patients with significant CA disease.

Cardiac magnetic resonance perfusion imaging for the functional assessment of coronary artery disease: a comparison with coronary angiography and fractional flow reserve

Cardiac magnetic resonance perfusion imaging (CMRI) is a promising technique for non-invasive measurement of myocardial perfusion reserve. Fractional flow reserve (FFR) is an established invasive method for functional assessment of coronary artery disease (CAD). To prospectively assess the diagnostic value of CMRI for the detection of haemodynamically significant coronary lesions, compared with coronary angiography (CA) and FFR. Forty-three patients with suspected or known CAD underwent CA, CMRI, and FFR measurement. First pass magnetic resonance perfusion examination was performed during hyperaemia (140 microg/kg/min adenosine over 6 min) and at rest. One hundred and twenty-nine perfusion territories were assessed by semi-quantitative evaluation of signal intensity-time curves using the myocardial perfusion reserve index (MPRI) [upslope(stress(corrected))/upslope(rest(corrected))]. Perfusion territories were categorized as normal (coronary stenosis < or = 50%), intermediate (stenosis > 50% and FFR > 0.75), or severe (stenosis > 50% and FFR < or = 0.75 or total occlusion). MPRI values (+/-SD) were significantly different between the three categories [normal, 2.2 +/- 0.5 vs. intermediate, 1.8 +/- 0.5 (P = 0.005) and intermediate vs. severe, 1.2 +/- 0.3 (P < 0.001)]. An MPRI cut-off value of 1.5 (derived from receiver operating characteristics analysis) distinguished haemodynamically relevant (severe) from non-relevant (normal and intermediate) stenoses with a sensitivity of 88% (CI 74-100%) and a specificity of 90% (CI 84-96%). In contrast to earlier studies that compared CMRI with morphological examination (CA) alone, the present study compared CMRI with CA plus a standard invasive functional assessment (FFR) and demonstrated that CMRI is able to distinguish haemodynamically relevant from non-relevant coronary lesions with a high sensitivity and specificity and may therefore contribute to clinical decision-making.

Limited Wegener's granulomatosis presenting with complete heart block

Complete heart block associated with Wegener's granulomatosis (WG) is rare, and has not previously been reported with ‘limited’ WG. The case of a 36‐year‐old man who presented with complete heart block due to ‘limited’ WG [positive cytoplasmic antineutrophil cytoplasmic antibodies (c‐ANCA) on indirect immunofluorescence, positive serum antibodies to proteinase‐3, and inflammatory sinus disease seen on computerized tomography (CT) without renal or pulmonary involvement] is presented. In addition, a gallium‐scan fused with a myocardial perfusion scan and cardiac magnetic resonance imaging (MRI) suggested focal inflammation near the atrioventricular (AV) node.

Hemorheological changes of microvasculature during development ofhypertension and repetitive smoke inhalation ore cholesterol feeding within the same cutaneous microcirculatory system in the rabbit

This study sought to test the hypothesis that transmural perfusion gradients (TPG) on adenosine stress myocardial perfusion cardiac magnetic resonance (CMR) predict hemodynamically significant coronary artery disease (CAD) as defined by fractional flow reserve (FFR).Myocardial ischemia affects the subendocardial layers of the left ventricular myocardium earlier and more severely than the outer layers, and the identification of TPG should be sensitive and specific for the diagnosis of CAD. Previous studies have shown that high spatial resolution myocardial perfusion CMR allows quantitation of TPG between the subendocardium and the subepicardium.Sixty-seven patients (53 men, age 61 ± 9 years) underwent coronary angiography and high-resolution (1.2 × 1.2-mm in-plane) adenosine stress perfusion CMR at 3.0-T. TPG was calculated for 3 coronary territories. Visual analysis was performed to identify myocardial ischemia. FFR was measured in all vessels with ≥50% severity stenosis. FFR <0.8 was considered hemodynamically significant. In a training group of 30 patients, the optimal threshold of TPG to detect significant CAD was determined (Group 1). This threshold was then tested prospectively in the remaining 37 patients (Group 2).In Group 1, a 20% TPG provided the best diagnostic threshold on both per-segment and per-patient analysis. Applied to Group 2, this threshold yielded a sensitivity of 0.78, specificity of 0.94, and area under the curve of 0.86 for the detection of CAD in a per-segment analysis and of 0.89, 0.83, and 0.86 in a per-patient analysis, respectively. TPG had a similar diagnostic accuracy to visual assessment. Linear regression analysis showed a relationship between TPG and FFR values, with r = 0.63 (p < 0.001).The quantitative analysis of transmural perfusion gradients on high-resolution myocardial perfusion CMR accurately predicts hemodynamically significant CAD as defined by FFR. A TPG diagnostic threshold of 20% is as accurate as visual assessment.