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A R Fuisz

Publications and source records attributed to A R Fuisz.

11 recordsLinked to original sources
PubMed2001

Real-time 3-dimensional echocardiographic evaluation of left ventricular volume: correlation with magnetic resonance imaging--a validation study.

BACKGROUND: The purpose of our study was to validate the ability of real-time 3-dimensional echocardiography (RT3D) to measure cardiac volume. METHODS: We studied 25 patients with various cardiac disorders who had a regular heart rhythm and a good precordial echocardiographic window. Each patient underwent complete transthoracic echocardiography (TTE), RT3D, and magnetic resonance imaging (MRI) studies. Left ventricular dimension was calculated from slices of the whole left ventricle obtained by 7 different equidistant azimuth tilts. Planimetry of the endocardial (for volume data) and epicardium (for mass data) surface was performed for each azimuth tilt. The left ventricular end-diastolic volume (LVEDV) and the left ventricular end-systolic volume (LVESV) were calculated. The cardiac mass data were derived with the formula (Epicardial volume - LVEDV) x 1.055. The parameters of LVEDV, LVESV, stroke volume, ejection fraction, and cardiac mass were compared with those derived from MRI. RESULTS: No statistically significant differences were found between the data from RT3D and MRI (P > or =.05). Good correlations were found between these two methods for left ventricle volume and mass measurements (r from 0.92 to 0.99). However, a weaker correlation was found with larger chamber sizes because extrapolation was necessary for the volume of myocardial segments that were not covered by the small sector angle. CONCLUSIONS: For data acquisition, RT3D is faster than either TTE or MRI. It is also better than MRI for measuring cardiac volume and mass. To improve results with larger cardiac chamber sizes, enlargement of the sector angle will be necessary.

Adult↗
PubMed2001

Validation of rapid velocity encoded cine imaging of a dynamically complex flow field using turbo block regional interpolation scheme for k space.

Block regional interpolation scheme for k space (BRISK) is a sparse sampling approach to allow rapid magnetic resonance imaging of dynamic events. Rapid velocity encoded cine (VEC) imaging with Turbo BRISK is potentially an important clinical diagnostic technique for cardiovascular diseases. Previously we applied BRISK and Turbo BRISK to imaging pulsatile flow in a straight tube. To evaluate the capabilities of Turbo BRISK imaging in more complex dynamic flow fields such as might exist in the human vasculature, an in vitro curved tube model, similar in geometry to the aortic arch, was fabricated and imaged under pulsatile flow conditions. Velocity maps were obtained using conventional VEC and Turbo BRISK (turbo factors 1 through 5). Comparison of the flow fields obtained with each higher order turbo factor showed excellent agreement with conventional VEC with minimal loss of information. Similarly, flow maps showed good agreement with the profiles from a laser Doppler velocimetry model. Turbo-5 BRISK, for example, allowed a 94% savings in imaging time, reducing the conventional imaging time from over 8 min to a near breath-hold imaging period of 31 s. Turbo BRISK shows excellent promise toward the development of a clinical tool to evaluate complex dynamic intravascular flow fields.

Biomedical Engineering↗
PubMed2000

Sensitivity and specificity of transesophageal echocardiography for determination of aortic valve morphology.

BACKGROUND: Preoperative recognition of the presence of bicuspid aortic valve can be important in the planning of procedures. Multiplane transesophageal echocardiography may allow more accurate detection of valvular morphology than does biplane transesophageal echocardiography. METHODS AND RESULTS: The studies of 710 patients who subsequently underwent valvular or aortic surgery were reviewed in a blinded fashion. The inclusion criteria were adequate short-axis view and operative note confirmation of aortic valve morphology. Six hundred eight patients were submitted to further analysis. Four hundred three patients had aortic stenosis as the primary diagnosis. Three hundred sixty patients had biplane examinations and 248 had multiplane examinations. The sensitivity and specificity of the multiplane technique in assessing aortic valve morphology (bicuspid vs tricuspid valve) was 87% and 91%, respectively. The sensitivity and specificity of the biplane technique was 66% and 56%, respectively. Whether valves were calcified or not did not result in major changes in sensitivity and specificity for either technique. CONCLUSIONS: Multiplane transesophageal echocardiography provides a more accurate assessment of preoperative aortic valve morphology than does the biplane approach in the majority of patients.

Adolescent↗
PubMed2000

Hemodynamic evaluation with TURBO BRISK--a rapid phase contrast angiography technique.

Hemodynamic imaging by phase contrast angiography was significantly accelerated by selective interpolation and segmentation in k-space using TURBO BRISK. The method was tested in vitro on three independent flowfields, representative of human blood rheology: a straight tube simulating the descending aorta, a curved tube simulating the aortic arch and a two-chamber orifice flow model simulating valvular regurgitation. The results were compared to data obtained by Laser Doppler Velocimetry (LDV) and showed good agreement. For the straight tube, the flow velocity obtained by five TURBO BRISK methods with increasing segmentation factors and corresponding time savings showed good agreement with LDV. For the curved tube, the velocity showed good general agreement with some differences in the decelerating part of the cycle, and in the low-velocity secondary flow structures. The orifice flow evaluation, the most time consuming case, was performed by the control volume method. It showed good agreement with actual flows through the orifice. Data acquisitions for TURBO-4 BRISK could be performed in 20s for each velocity component. The method shows promise for breath-hold acquisitions in clinical applications, including calculation of blood flow volumes through diseased arteries, measurement of blood backflow volumes through dysfunctional heart valves to time valve replacement operations, and evaluation of arterial wall shear stress, an important factor in the genesis of atherosclerosis.

Aorta, Thoracic↗
PubMed1999

Coronary flow velocity response to adenosine characterizes coronary microvascular function in women with chest pain and no obstructive coronary disease. Results from the pilot phase of the Women's Ischemia Syndrome Evaluation (WISE) study.

OBJECTIVES: We sought to develop and validate a definition of coronary microvascular dysfunction in women with chest pain and no significant epicardial obstruction based on adenosine-induced changes in coronary flow velocity (i.e., coronary velocity reserve). BACKGROUND: Chest pain is frequently not caused by fixed obstructive coronary artery disease (CAD) of large vessels in women. Coronary microvascular dysfunction is an alternative mechanism of chest pain that is more prevalent in women and is associated with attenuated coronary volumetric flow augmentation in response to hyperemic stimuli (i.e., abnormal coronary flow reserve). However, traditional assessment of coronary volumetric flow reserve is time-consuming and not uniformly available. METHODS: As part of the Women's Ischemia Syndrome Evaluation (WISE) study, 48 women with chest pain and normal coronary arteries or minimal coronary luminal irregularities (mean stenosis = 7%) underwent assessment of coronary blood flow reserve and coronary flow velocity reserve. Blood flow responses to intracoronary adenosine were measured using intracoronary Doppler ultrasonography and quantitative angiography. RESULTS: Coronary volumetric flow reserve correlated with coronary velocity reserve (Pearson correlation = 0.87, p < 0.001). In 29 (60%) women with abnormal coronary microcirculation (mean coronary flow reserve = 1.84), adenosine increased coronary velocity by 89% (p < 0.001) but did not change coronary cross-sectional area. In 19 (40%) women with normal microcirculation (mean flow reserve = 3.24), adenosine increased coronary velocity and area by 179% (p < 0.001) and 17% (p < 0.001), respectively. A coronary velocity reserve threshold of 2.24 provided the best balance between sensitivity and specificity (90% and 89%, respectively) for the diagnosis of microvascular dysfunction. In addition, failure of the epicardial coronary to dilate at least 9% was found to be a sensitive (79%) and specific (79%) surrogate marker of microvascular dysfunction. CONCLUSIONS: Coronary flow velocity response to intracoronary adenosine characterizes coronary microvascular function in women with chest pain in the absence of obstructive CAD. Attenuated epicardial coronary dilation response to adenosine may be a surrogate marker of microvascular dysfunction in women with chest pain and no obstructive CAD.

Adenosine↗
PubMed1999

Syncope and inducible ventricular fibrillation in a woman with hemochromatosis.

BACKGROUND: Hemochromatosis has been associated with atrial tachyarrhythmias and congestive heart failure as a consequence of dilated or restrictive cardiomyopathy. Inducible ventricular fibrillation has not been previously described. METHODS AND RESULTS: An electrophysiologic study was conducted in a woman after two episodes of syncope. Polymorphic ventricular tachycardia (PMVT) and ventricular fibrillation (VF) were induced with ventricular programmed stimulation. Magnetic resonance imaging demonstrated signal loss in the liver consistent with hemochromatosis, but normal cardiac size and function. Hematologic studies supported a diagnosis of hemochromatosis. CONCLUSION: Cardiac hemochromatosis may be associated with serious ventricular arrhythmias.

Echocardiography↗
PubMed1999

Rapid velocity-encoded cine imaging with turbo-BRISK.

Velocity-encoded cine (VEC) imaging is potentially an important clinical diagnostic technique for cardiovascular diseases. Advances in gradient technology combined with segmentation approaches have made possible breathhold VEC imaging, allowing data to be obtained free of respiratory artifacts. However, when using conventional segmentation approaches, spatial and temporal resolutions are typically compromised to accommodate short breathhold times. Here we apply a sparse sampling technique, turbo-BRISK (i.e., segmented block regional interpolation scheme for k-space) to VEC imaging, allowing increased spatial and temporal resolution to be obtained in a short breathhold period. BRISK is a sparse sampling technique with interpolation used to generate unsampled data. BRISK was implemented to reduce the scan time by 70% compared with a conventional scan. Further, turbo-BRISK scans, using segmentation factors up to 5, reduce the scan time by up to 94%. Phantom and in vivo results are presented that demonstrate the accuracy of turbo-BRISK VEC imaging. In vitro validation is performed using conventional magnetic resonance VEC. Pulsatile centerline flow velocity measurements obtained with turbo-BRISK acquisitions were correlated with conventional magnetic resonance imaging measurements and achieved r values of 0.99 +/- 0.004 (mean +/- SD) with stroke volumes agreeing to within 4%. A potential limitation of BRISK is reduced accuracy for rapidly varying velocity profiles. We present low- and high-resolution data sets to illustrate the resolution dependence of this phenomenon and demonstrate that at conventional resolutions, turbo-BRISK can accurately represent rapid velocity changes. In vivo results indicate that centerline velocity waveforms in the descending aorta correlate well with conventional measurements with an average r value of 0.98 +/- 0.01.

Blood Flow Velocity↗
PubMed1998

Imaging cardiac structure and pump function.

This article describes magnetic resonance imaging approaches for assessing cardiac structure and myocardial pump function. The article is divided into cardiac structure and ventricular function. Throughout, representative images are included. There are numerous applications of magnetic resonance imaging for assessing cardiac structure and function, and magnetic resonance imaging compared favorably to other imaging modalities.

Heart↗
PubMed1998

Magnetic resonance angiography.

Since the emergence of magnetic resonance (MR) imaging, its clinical applications have seen a logarithmic growth. The advantage of MR imaging is that it offers a vast amount of important clinical information with minimal risk to the patient, and promises to reduce the need for angiographic studies with their attendant morbidity and mortality. We review the applications and recent advances of MR imaging to include coronary imaging of native, bypassed and stented vessels, carotid arteries, peripheral arteries, and the aorta. In addition, we discuss issues of patient preferences and the future directions of MR imaging. We predict that the clinical utility of MR angiography will grow with refinements that will improve speed, resolution, and even the use of spectroscopy to characterize plaque.

Aorta↗