Diagnostic accuracy of quantitative cardiac MRI evaluation compared to stress single-photon-emission computed tomography.

BACKGROUND: Cardiac MRI (cMRI) perfusion is a promising non-invasive tool to assess myocardial ischemia. The accuracy of quantitative cMRI perfusion has been recently demonstrated, but to date no previous study has compared this technique with stress single-photon-emission computed tomography (SPECT). The aim of this study was to evaluate the diagnostic accuracy of myocardial perfusion reserve (MPR) based on cMRI compared with SPECT. METHODS: We examined 24 patients who underwent coronary angiography, stress SPECT and cMRI perfusion. Qualitative assessment of both SPECT and cMRI images, quantification of cMRI perfusion, and quantitative coronary angiography (QCA) were independently performed. MPR was calculated using Fermi deconvolution technique. Accuracy of quantitative and qualitative data was examined to detect > 50% diameter stenosis (DS) by QCA. RESULTS: Qualitative analysis was obtained in 198 segments and quantitative analysis was performed in 171 segments. Significant coronary artery disease (CAD) was present in 81.8% of patients. Visual cMRI assessment yielded sensitivity of 74.4% and specificity of 79.4% to predict > 50%DS, while SPECT showed sensitivity of 67.4% and specificity of 81.3%. The sensitivity for SPECT in the right coronary artery territory and apex was low compared to cMRI. Sensitivity and specificity for detection of significant CAD were 89.5% and 46.6% for MPR (cutoff 1.92). Area under the curve was 0.75 for MPR (P < 0.01). CONCLUSIONS: The diagnostic accuracy of qualitative examination of perfusion cardiac MRI and stress SPECT were comparable. The high sensitivity and low operator dependency of quantitative cMRI makes it an attractive tool to evaluate myocardial perfusion.

Quantitative magnetic resonance perfusion imaging detects anatomic and physiologic coronary artery disease as measured by coronary angiography and fractional flow reserve.

OBJECTIVES: 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. BACKGROUND: 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. METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.

BACKGROUND: 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). METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.

Magnetic resonance quantitative myocardial perfusion reserve demonstrates improved myocardial blood flow after angiogenic implant therapy.

PURPOSE: The purpose of this study is to follow myocardial angiogenesis temporally using quantitative magnetic resonance first pass perfusion imaging and compare this with the "gold standard" of radioactive microspheres in a random subset of animals. MATERIALS AND METHODS: Ameriod constrictors were placed around the left circumflex in 15 pigs to induce an ischemic area. Two groups were randomized to receive either a sham operation or treatment with angiogenic implants inserted into myocardium in the distribution of the left circumflex artery (LCX). These implants are designed to induce myocardial angiogenesis. Magnetic resonance first pass perfusion imaging was performed at baseline and also after treatment with either sham or implant therapy by using first pass perfusion imaging with a TurboFLASH sequence. Absolute myocardial blood flow was derived by applying a quantitative Fermi function model. Radioactive microspheres were also injected into a random subset of animals to measure myocardial blood flow. RESULTS: Angiogenic implant therapy increased absolute myocardial blood flow in the left circumflex territory relative to baseline and sham treated groups during adenosine infusion. Myocardial blood flows measured with radioactive microspheres was increased significantly in both the LCX and LAD territories during stress. Myocardial Perfusion reserve was also significantly increased in both the LCX and left anterior descending territories relative to baseline. Ejection Fraction during stress with dobutamine infusion increased significantly in the implant therapy group while that in the sham group was not affected. CONCLUSION: Quantitative MR myocardial first pass perfusion imaging can be used to track the development of angiogenesis as corroborated by radioactive microspheres. Angiogenic implant therapy is a new device based therapy that has potential to protect an ischemic region by accelerating angiogenesis although further research is necessary with this device.

Magnetic resonance first pass perfusion imaging for detecting coronary artery disease.

Magnetic resonance first pass perfusion imaging can be used to detect abnormalities in myocardial blood flow. This technique involves imaging the first pass of gadolinium based contrast through the myocardium. Images are initially read qualitatively for areas of reduced signal intensity. Additionally, at our institution a quantitative method is applied that can aid both detection and diagnosis of perfusion defects. This method involves fitting the myocardial signal intensity curves and then calculates absolute myocardial blood flow. Our approach to first pass perfusion imaging will be reviewed. Magnetic resonance first pass perfusion imaging has a complimentary role with coronary angiography either non-invasively using CT or with catheterization. Perfusion imaging defines the physiology and angiography in the anatomy of coronary artery disease.