Munenobu Motoyasu

Evaluation of Left Ventricular Volumes and Ejection Fraction Using Fast Steady-State Cine MR Imaging: Comparison with Left Ventricular Angiography

Previous studies demonstrated that magnetic resonance (MR) imaging consistently underestimated angiographic measurements of left ventricular (LV) volumes. The purpose of this study was to determine whether MR imaging with steady-state free precession acquisition (SSFP) can provide improved accuracy and reproducibility in measuring cardiac function in comparison with fast spoiled gradient echo cine MR imaging (SPGR). Twenty patients with cardiovascular diseases who underwent breath-hold cine MR imaging within one week of LV angiography were studied. Two sets of breath-hold cine MR images were obtained, one with SSFP and another with SPGR. The LV volumes determined by two breath-hold cine MR sequences were compared with the results by LV angiography. SPGR cine MR imaging consistently underestimated angiographic LV volumes. The mean difference of LV end-diastolic volume was -22.5 +/- 14.8 ml (p < 0.001) for short-axis planes and -27.7 +/- 21.5 ml (p < 0.001) for long-axis planes. In contrast, LV volumes measured by the SSFP imaging showed a good agreement with the results by angiography. The mean difference of LV end-diastolic volume was -2.5 +/- 14.3 ml (p = N.S.) for short-axis planes and -10.9 +/- 15.1 ml (p < 0.01) for long-axis planes. Standard error of the estimation in measuring LV end-diastolic volume with the SSFP imaging was 3.9% for short-axis images and 4.9% for long-axis images. These values were 7.2% and 8.7% with the SPGR imaging. In conclusion, the SSFP acquisition can provide accurate and noninvasive assessments of LV volumes and ejection fraction within a reduced imaging time.

Prediction of regional functional recovery after acute myocardial infarction with low dose dobutamine stress cine MR imaging and contrast enhanced MR imaging

PURPOSE Previous studies demonstrated that low-dose dobutamine stress cine magnetic resonance imaging (MRI) and delayed contrast-enhanced MRI can provide assessments of myocardial viability. The purpose of this study was to evaluate the comparative diagnostic values of dobutamine cine MRI and delayed contrast-enhanced MRI for predicting functional recovery of myocardial contraction in patients with acute reperfused myocardial infarction. METHODS Twenty-three patients with myocardial infarction after percutaneous coronary interventions were studied. All patients underwent steady-state cine MRI covering the entire left ventricle at rest and during low-dose dobutamine stress (10 micrograms/kg/min). Delayed contrast-enhanced MR images were acquired to determine transmural extent of hyperenhancement. Second cine MR images in the resting state were obtained 3 to 11 months after revascularization. RESULTS On the first cine MR images in the resting state, 278 (20%) of 1380 segments demonstrated abnormal, regional contraction (systolic wall thickening < 40%). Of the 175 segments showing functional recovery on the following cine MRI, 156 (89%) segments were recognized as reversible by dobutamine cine MRI and 146 (83%) segments by delayed contrast-enhanced MRI. The sensitivity, specificity, and accuracy of dobutamine stress cine MRI was 89%, 80%, and 86%, respectively. These values of contrast-enhanced MRI were 83%, 72%, and 79%, respectively. The area under the receiver operating curve (ROC) was 0.87 by dobutamine cine MRI and 0.78 by delayed contrast-enhanced MRI (p < 0.05). CONCLUSIONS The current results using quantitative segmental analysis indicated that low-dose dobutamine stress cine MRI can predict recovery of myocardial contractility with significantly higher diagnostic performance in comparison with contrast-enhanced MRI in patients with myocardial infarction who underwent revascularization.

Effects of therapeutic doses of human atrial natriuretic peptide on load and myocardial performance in patients with congestive heart failure.

The benefits of atrial natriuretic peptide (ANP) in patients with congestive heart failure (CHF) have been demonstrated. However, the myocardial actions of ANP remain unclear. Using relatively load-insensitive left ventricular pressure-volume analysis, the myocardial and load-altering actions of ANP in patients with moderate CHF were studied. After obtaining steady-state data using micromanometers and conductance catheters, ANP was infused in 9 patients with CHF at 0.01 and 0.1 microg/kg/min for 30 minutes, respectively. Hemodynamic variables, plasma ANP, and cyclic guanosine monophosphate (cGMP) levels were determined before and 30 minutes after each ANP infusion. ANP at 0.01 microg/kg/min increased plasma ANP and cGMP levels from 73 +/- 34 to 139 +/- 34 pg/ml and from 4 +/- 1 to 8 +/- 2 pmol/ml, respectively. ANP infusion caused a significant decrease in end-systolic pressure without any changes in heart rate. End-diastolic pressure was significantly decreased but there was no significant change in left ventricular end-diastolic volume. The time constant for isovolumetric relaxation was decreased. ANP infusion at 0.1microg/kg/min caused further decreases in end-systolic pressure, end-diastolic pressure and volume, and the time constant for isovolumetric relaxation (p <0.05) without any changes in heart rate. The slope of the end-systolic pressure-volume relation was increased from 1.3 +/- 0.2 to 1.6 +/- 0.3 mm Hg/ml (p <0.05), indicating increased contractility. Plasma ANP and cGMP levels were increased to 422 +/- 44 pg/ml and 16 +/- 3 pmol/ml, respectively. Thus, ANP infusion increased cGMP generation, decreased afterload and preload, and improved left ventricular systolic and diastolic function.

A case of inverted left atrial appendage mimicking a tumor.

We report a rare case of an inverted left atrial appendage without prior cardiac surgery. A left atrial mass was incidentally found during routine echocardiography in a 19-year-old man with mitral valve prolapse. Echocardiography revealed a hyperechoic mass in the left atrium, and a neoplastic lesion could not be excluded. On magnetic resonance imaging (MRI), this mass consisted of fat tissue that showed continuation to epicardial fat, indicating an inverted left atrial appendage mimicking a tumor in the left atrium. When a mass in the left atrium is observed on echocardiography, there are several differential diagnoses, including thrombus, vegetation, and intra-atrial neoplasms such as myxomas. Recently, several studies reported cases with inverted left atrial appendages mimicking tumors in patients after cardiac operations. We present a case of inverted left atrial appendage without any prior cardiac surgery. Cardiac MRI was highly useful to obtain the final diagnosis of inverted left atrial appendage.

Thallium-201 SPECT and Low-Dose Dobutamine Stress Cine MRI for Predicting Functional Recovery of Regional Myocardial Contraction in Patients with Myocardial Infarction

OBJECTIVES The purpose of this study was to compare the diagnostic performances of Tl-201 single photon emission computed tomography (SPECT) and dobutamine stress cine magnetic resonance imaging (MRI) for predicting functional recovery of regional myocardial contraction in patients after myocardial infarction. METHODS Twenty patients underwent Tl-201 SPECT and MRI 3-4 weeks after onset of myocardial infarction. Cine MR images were acquired in the resting state and during dobutamine stress. Tl-201 uptake and systolic wall thickening (SWT) on cine MRI were analyzed on short-axis images by using a 14-segment model. Follow-up cine MR images were obtained 187.1+/-33.5 days after onset. RESULTS The averaged Tl-201 uptake in 54 segments with impaired SWT was 47%+/-20%, being significantly lower than that in 226 segments with preserved SWT (75%+/-18%; p<0.0001). The sensitivity, specificity, and accuracy of dobutamine MRI and Tl-201 SPECT for predicting preserved SWT after 6 months were 89% vs. 80%, not significant (NS); 89% vs. 72%, p<0.01; and 89% vs. 79%, NS, respectively. In the anterior wall and apex, the sensitivity and specificity of SPECT were not significantly different from those of MRI. In the inferior wall and posterolateral wall, however, the specificity of SPECT was substantially lower than that of MRI (53% vs. 88%, p<0.001), resulting in significantly lower accuracy (75% vs. 90%, p<0.01). CONCLUSIONS Both SPECT and dobutamine MRI showed excellent sensitivity for predicting myocardial viability in all left ventricular segments. Decreased specificity of SPECT in the inferior and posterolateral segments resulted in lower overall specificity in comparison with dobutamine MRI.

855-3 Correlation between hyperenhancement on delayed contrast enhanced magnetic resonance imaging (MRI) and diastolic function assessed by steady state cine MRI in hypertrophic cardiomyopathy

No ni nv as iv e Im ag in g vidual data was analyzed across the entire Q range of 0.1 to 5.0 ml/min/g, as well as in different narrow Q ranges to obtain PS dependence on Q. Results: Table I demonstrates that PS for TL is significantly higher than MIBI for all the STs. The correlation between mean ST flow and mean PS suggests PS dependence on Q. Additional estimates of PS in narrow Q bands shows similar influence of Q on PS under each of the three STs. Conclusion: PS appears different under the various STs. However, these differences can be mainly attributed to differences in Q. The results suggest that PS, and hence rolloff effects, are present at substantially lower flows than predicted by constant PS theory. .