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Raymond J Kim

Publications and source records attributed to Raymond J Kim.

At least 19 recordsLinked to original sources
PubMed2007

Rapid detection of myocardial infarction by subsecond, free-breathing delayed contrast-enhancement cardiovascular magnetic resonance.

BACKGROUND: An ultrafast, delayed contrast-enhancement cardiovascular magnetic resonance technique that can acquire subsecond, "snapshot" images during free breathing (subsecond) is becoming widely available. This technique provides myocardial infarction (MI) imaging with complete left ventricular coverage in < 30 seconds. However, the accuracy of this technique is unknown. METHODS AND RESULTS: We prospectively compared subsecond imaging with routine breath-hold delayed contrast-enhancement cardiovascular magnetic resonance (standard) in consecutive patients. Two cohorts with unambiguous standards of truth were prespecified: (1) patients with documented prior MI (n=135) and (2) patients without MI and with low likelihood of coronary disease (lowest Framingham risk category; n=103). Scans were scored masked to identity and clinical information. Sensitivity, specificity, and accuracy of subsecond imaging for MI diagnosis were 87%, 96%, and 91%, respectively. Compared with the standard technique (98%, 100%, 99%), the subsecond technique had modestly reduced sensitivity (P=0.0001), but specificity was excellent. Missed infarcts were generally small or subendocardial (87%). Overall, regional transmural extent of infarction scores were highly concordant (2083/2294; 91%); however, 51 of 337 regions (15%) considered predominantly infarcted (> 50% transmural extent of infarction) by the standard technique were considered viable (< or = 25% transmural extent of infarction) by the subsecond technique. Quantitative analysis demonstrated moderately reduced contrast-to-noise ratios for subsecond imaging between infarct and remote myocardium (12.0+/-7.2 versus 20.1+/-6.6; P<0.0001) and infarct and left ventricular cavity (-2.5+/-2.7 versus 3.6+/-3.7; P<0.0001). CONCLUSIONS: MI can be rapidly detected by subsecond delayed contrast-enhancement cardiovascular magnetic resonance during free breathing with high accuracy. This technique could be considered the preferred approach in patients who are more acutely ill or unable to hold their breath. However, compared with standard imaging, sensitivity is mildly reduced, and the transmural extent of infarction may be underestimated.

Adult↗
PubMed2006

ACCF/ACR/SCCT/SCMR/ASNC/NASCI/SCAI/SIR 2006 appropriateness criteria for cardiac computed tomography and cardiac magnetic resonance imaging: a report of the American College of Cardiology Foundation Quality Strategic Directions Committee Appropriateness Criteria Working Group, American College of Radiology, Society of Cardiovascular Computed Tomography, Society for Cardiovascular Magnetic Resonance, American Society of Nuclear Cardiology, North American Society for Cardiac Imaging, Society for Cardiovascular Angiography and Interventions, and Society of Interventional Radiology.

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Cardiovascular Diseases↗
PubMed2006

Diagnostic testing.

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Diagnostic Techniques, Cardiovascular↗
PubMed2006

Effects of time, dose, and inversion time for acute myocardial infarct size measurements based on magnetic resonance imaging-delayed contrast enhancement.

OBJECTIVES: This study sought to investigate the influence of time, dose, and inversion time (TI) and their interactions on myocardial infarct size measurements to establish the foundation for a standardized protocol for multicenter trials. BACKGROUND: There is growing interest in using magnetic resonance imaging (MRI) infarct size measurements as an end point in clinical trials. However, no standardized protocol exists, and there are limited data concerning the effects of time, contrast agent dose, and TI. METHODS: First, we determined the influence of postcontrast imaging time (5 to 40 min), contrast agent dose (0.1 vs. 0.2 mmol/kg), TI, and their interactions in an animal model (n = 14). Second, we tested whether the findings of the animal study apply to patients and are generalizable. Therefore, we retested the diagnostic window in a multicenter study. A total of 48 patients with first acute myocardial infarction (AMI) from three centers were imaged twice (5 and 30 min) after injection of 0.15 mmol/kg gadolinium diethylenetriamine-pentaacetate using an adjusted TI. RESULTS: The animal study showed that the infarct size is independent of time and dose (p = 0.9 and p = 0.16, respectively) using an adjusted TI. Using a fixed TI, however, infarct size is a function of time and dose (p = 0.0001 and p = 0.01, respectively). The multicenter study showed that MRI 1 (16.9 +/- 12% of left ventricle) was not statistically different from MRI 2 (16.4 +/- 12% of left ventricle, p = NS) with no difference between sites (p = NS). CONCLUSIONS: The AMI size can be measured with MRI using a contrast dose between 0.1 and 0.2 mmol/kg and a time window of 5 to 30 min after contrast administration, provided that the TI is adjusted.

Adult↗
PubMed2006

Improved detection of coronary artery disease by stress perfusion cardiovascular magnetic resonance with the use of delayed enhancement infarction imaging.

OBJECTIVES: We tested a pre-defined visual interpretation algorithm that combines cardiovascular magnetic resonance (CMR) data from perfusion and infarction imaging for the diagnosis of coronary artery disease (CAD). BACKGROUND: Cardiovascular magnetic resonance can assess both myocardial perfusion and infarction with independent techniques in a single session. METHODS: We prospectively enrolled 100 consecutive patients with suspected CAD scheduled for X-ray coronary angiography. Patients had comprehensive clinical evaluation, including Rose angina questionnaire, 12-lead electrocardiography, C-reactive protein, and calculation of Framingham risk. Cardiovascular magnetic resonance included cine, adenosine-stress and rest perfusion-CMR, and delayed enhancement-CMR (DE-CMR) for infarction imaging. Matched stress-rest perfusion defects in the absence of infarction by DE-CMR were considered artifactual. All patients underwent X-ray angiography within 24 h of CMR. RESULTS: Ninety-two patients had complete CMR examinations. Significant CAD (> or =70% stenosis) was found in 37 patients (40%). The combination of perfusion and DE-CMR had a sensitivity, specificity, and accuracy of 89%, 87%, and 88%, respectively, for CAD diagnosis, compared with 84%, 58%, and 68%, respectively, for perfusion-CMR alone. The combination had higher specificity and accuracy (p < 0.0001), owing to incorporating the exceptionally high specificity (98%) of DE-CMR. Receiver operating characteristic curve analysis demonstrated the combination provided better performance than cine, perfusion, or DE-CMR alone. The accuracy was high in single-vessel and multivessel disease and independent of CAD location. Multivariable analysis including standard clinical parameters demonstrated the combination was the strongest independent CAD predictor. CONCLUSIONS: A combined perfusion and infarction CMR examination with a visual interpretation algorithm can accurately diagnose CAD in the clinical setting. The combination is superior to perfusion-CMR alone.

Aged↗
PubMed2006

Assessment of no-reflow regions using cardiac MRI.

Ischemic myocardial injury can be broadly characterized as either reversible or irreversible. Within irreversibly injured (infarcted) regions microvascular perfusion can vary from nearly normal to nearly zero, even in the presence of an open infarct-related artery ('no-reflow'). Historically, non-invasive assessment of heterogeneous microvascular perfusion within myocardial infarcts has been problematic. More recently, however, contrast-enhanced MRI has emerged as a promising approach to the examination of these regions in patients with myocardial infarction. In this review we highlight a number of important animal and human studies of no-reflow regions examined using contrast-enhanced MRI. These studies provide evidence that contrast- enhanced MRI can accurately characterize the presence and spatial extent of no-reflow regions, discriminate between areas of necrosis with and without no-reflow, and provide clinically meaningful predictive information regarding left ventricular remodeling and patient outcome.

Animals↗
PubMed2006

Where's the flap?

We present a case of aortic intramural hematoma (IMH) in an elderly woman who presented with sudden onset of mid-scapular pain. The patient underwent a series of multimodality imaging studies before the diagnosis of IMH was evident by cardiovascular magnetic resonance, which is rapidly becoming the gold standard in the evaluation of acute aortic disease due to its high spatial resolution and ability to characterize tissue composition. Early diagnosis and prompt treatment is critical in improving the outcome of patients with IMH.

Aged↗
PubMed2006

Acute myocardial infarction: safety of cardiac MR imaging after percutaneous revascularization with stents.

PURPOSE: To retrospectively determine the safety of cardiac magnetic resonance (MR) imaging performed early (<14 days) after coronary stent implantation in patients with acute myocardial infarction (AMI). MATERIALS AND METHODS: This HIPPA-compliant study was approved by the institutional review board; the informed consent requirement was waived. Consecutive patients with AMI who underwent cardiac MR imaging (study group) shortly after stent implantation (median, 3 days) were compared with control subjects who did not undergo MR imaging and were matched for clinical factors and angiographic extent of coronary disease. A 1.5-T MR imager was used to evaluate cine function, perfusion, and viability. Rates of death, nonfatal myocardial infarction, or revascularization 30 days and 6 months after stent implantation were compared with chi(2) analysis. RESULTS: The study group consisted of 66 patients (median age, 56 years; 17 women) with 97 stents, 38 (39%) of which were drug eluting. The control group included 124 patients (median age, 58 years; 23% women) with 197 stents, 21 (10.7%) of which were drug eluting. There was no significant (P = .13) difference in the combined end point of death, nonfatal myocardial infarction, or revascularization between the study (2.0% [95% confidence interval: 0.0%, 4.5%]) and control (6.5% [95% confidence interval: 1.6%, 11.3%]) groups at 30-day follow-up. The event-free survival rate at 6-month follow-up was 91% in the study group and 83.7% in the control group (P = .18). Considering the end points separately, there was no difference in the event rate at 30-day or 6-month follow-up between groups. No adverse cardiovascular events occurred in patients with drug-eluting stents who underwent MR imaging. CONCLUSION: Cardiac MR imaging performed shortly after AMI and percutaneous revascularization with bare metal or drug-eluting stents appears safe. The risk of adverse cardiovascular events is low and similar to that in patients who do not undergo MR imaging.

Aged↗
PubMed2005

Delayed enhancement cardiovascular magnetic resonance assessment of non-ischaemic cardiomyopathies.

Non-ischaemic cardiomyopathies (NICMs) are chronic, progressive myocardial diseases with distinct patterns of morphological, functional, and electrophysiological changes. In the setting of cardiomyopathy (CM), determining the exact aetiology is important because the aetiology is directly related to treatment and patient survival. Determining the exact aetiology, however, can be difficult using currently available imaging techniques, such as echocardiography, radionuclide imaging or X-ray coronary angiography, since overlap of features between CMs may be encountered. Cardiovascular magnetic resonance (CMR) imaging has recently emerged as a new non-invasive imaging modality capable of providing high-resolution images of the heart in any desired plane. Delayed contrast enhanced CMR (DE-CMR) can be used for non-invasive tissue characterization and may hold promise in differentiating ischaemic from NICMs, as the typical pattern of hyperenhancement can be classified as 'ischaemic-type' or 'non-ischaemic type' on the basis of pathophysiology of ischaemia. This article reviews the potential of DE-CMR to distinguish between ischaemic and NICM as well as to differentiate non-ischaemic aetiologies. Rather than simply describing various hyperenhancement patterns that may occur in different disease states, our goal will be (i) to provide an overall imaging approach for the diagnosis of CM and (ii) to demonstrate how this approach is based on the underlying relationships between contrast enhancement and myocardial pathophysiology.

Cardiomyopathies↗
PubMed2005

Infarct morphology identifies patients with substrate for sustained ventricular tachycardia.

OBJECTIVES: We sought to evaluate whether infarct size characterization by cardiac magnetic resonance imaging (MRI) is a better predictor of inducible ventricular tachycardia (VT) than left ventricular ejection fraction (LVEF). BACKGROUND: Inducibility of VT at electrophysiologic study (EPS) and low LVEF can identify patients with a substrate for VT. Magnetic resonance imaging has been shown to identify, with high precision, areas of myocardial infarction and may therefore be a better tool to evaluate for a substrate for VT. METHODS: We studied 48 patients with known coronary artery disease who were referred for EPS using cine and gadolinium-enhanced MRI. Wall motion and infarct characteristics were determined blindly and compared among patients with no inducible ventricular arrhythmias (n = 21), those with inducible monomorphic VT (MVT, n = 18), and those with either inducible polymorphic VT or ventricular fibrillation (n = 9). RESULTS: Patients with MVT had larger infarcts than patients who did not have inducible arrhythmias (mass: 49 +/- 5 g [SE] vs. 28 +/- 5 g, p < 0.005; surface area: 172 +/- 15 cm(2) vs. 93 +/- 14 cm(2), p < 0.0005). Patients with polymorphic VT/fibrillation had intermediate values (mass: 36 +/- 7 g; surface area: 115 +/- 22 cm(2)). Ejection fraction was inversely related to infarct mass and surface area, with R(2) values ranging from 0.21 to 0.27. Logistic regression and receiver-operating characteristic analysis demonstrated that infarct mass and surface area were better predictors of inducibility of MVT than LVEF. CONCLUSIONS: Infarct surface area and mass, as measured by cardiac MRI, are better identifiers of patients who have a substrate for MVT than LVEF. Further evaluation of infarct size characterization by cardiac MRI as a predictor of sudden cardiac death is warranted.

Female↗
PubMed2005

Noninvasive assessment of blood flow based on magnetic resonance global coherent free precession.

BACKGROUND: Magnetic resonance global coherent free precession (GCFP) is a new technique that produces cine projection angiograms directly analogous to those of x-ray angiography noninvasively and without a contrast agent. In this study, we compared GCFP blood flow with "gold standards" to determine the accuracy of noninvasive GCFP blood flow measurements. METHODS AND RESULTS: The relationship between GCFP blood flow and true blood flow defined by invasive ultrasonic flow probe and by phase contrast velocity encoded MRI (VENC) was studied in anesthetized dogs (n=6). Blood flow was controlled by use of a hydraulic occluder around the left iliac artery. GCFP images were acquired by selectively exciting the abdominal aorta and visualizing temporal blood flow into the iliac arteries. GCFP flow was similar to ultrasonic blood flow at baseline (131.3+/-44.8 versus 114.8+/-34.2 mL/min), during occlusion (10.8+/-5.1 versus 6.5+/-7.2 mL/min), during reactive hyperemia (191.4+/-100.7 versus 260.3+/-138.7 mL/min), during the new resting state (135.5+/-52.4 versus 117.8+/-24.1 mL/min), and during partial occlusion (61.4+/-36.4 versus 49.3+/-13.1 mL/min, P=NS for all). Results comparing GCFP flow with VENC were similar. Statistical analysis revealed that GCFP flow was related to mean blood flow assessed by the flow probe (P<0.0001) and by VENC (P<0.0001). In the control right iliac artery, conversely, GCFP measurements were unaffected throughout all left iliac interventions (P=NS). CONCLUSIONS: GCFP blood flow is linearly related to true blood flow for a straight, cylindrical blood vessel without branches. Although more complex geometries imply a qualitative rather than a quantitative relationship, the data nevertheless suggest that GCFP may serve as the basis for a new form of noninvasive stress testing.

Animals↗
PubMed2005

23Na MRI combined with contrast-enhanced 1H MRI provides in vivo characterization of infarct healing.

Although (23)Na MRI has been shown to delineate acute myocardial infarction (MI), the time course of in vivo (23)Na MRI during infarct healing remains unknown. In this study (23)Na MRI was combined with contrast-enhanced (CE) (1)H MRI to noninvasively characterize infarct healing in vivo. Serial in vivo 3D (23)Na MRI and (1)H MRI were performed for up to 9 weeks postinfarction in 10 dogs. Radioactive microspheres were used to measure myocardial perfusion, and Hematoxylin-Eosin (H&E) and Masson's trichrome (MT) staining were used to assess interstitial cell infiltrate and collagen content. In vivo (23)Na MRI accurately delineated infarct size up to day 5 postinfarction in comparison with (1)H MRI (8.9% +/- 8.1% vs. 8.6% +/- 7.9% on day 1 postinfarction, P = NS; and 6.3% +/- 6.2% vs. 6.2% +/- 6.2% on days 4/5 postinfarction, P = NS). The in vivo (23)Na MRI signal intensity, expressed as the signal intensity ratio of infarcted tissue vs. noninfarcted tissue (MI/R) peaked on day 1 of infarction (2.04 +/- 0.23) but decreased significantly to 1.27 at 9 weeks postinfarction (P < 0.05) due to granulation tissue infiltrate and collagen deposition. To confirm the MI/R decrease during scar formation ex vivo, we performed (23)Na MRI in 12 rats on day 3 post-MI (N = 5) and after 6 weeks (N = 7). H&E and Picrosirius Red staining confirmed granulation tissue infiltrate on day 3 and scar formation after 6 weeks. MI/R decreased significantly from 1.91 +/- 0.45 on day 3 post-MI to 1.3 +/- 0.09 after 6 weeks. Thus, in vivo (23)Na MRI accurately delineates infarct size up to day 5 postinfarction. In vivo (23)Na MRI signal intensity decreases during infarct healing as a result of the underlying infarct healing process.

Analysis of Variance↗
PubMed2005

Use of cardiac magnetic resonance to assess viability.

The accurate differentiation of viable and nonviable myocardium is crucial for therapy planning in patients with coronary artery disease and left ventricular dysfunction. Traditional techniques such as echocardiography, positron emission tomography, single photon emission computed tomography, and dobutamine echocardiography have established roles. Cardiac MRI (CMR) is a rapidly emerging new modality that is used at an increasing number of medical centers in Europe and the United States. This review describes the role of CMR for the assessment of myocardial viability in the setting of acute and chronic ischemic ventricular dysfunction.

Coronary Artery Disease↗