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doi: 10.1023/A:1010611530845pmid: 11587450
The study of atherosclerotic disease during its natural history and after therapeutic intervention may enhance our understanding of the progression and regression of this disease and will aid in selecting the appropriate medical treatments or surgical interventions. Several invasive and non-invasive imaging techniques are available to assess atherosclerotic disease vessels. Most of these techniques are strong in identifying the morphological features of the disease such as lumenal diameter and stenosis or wall thickness, and in some cases provide an assessment of the relative risk associated with the atherosclerotic disease. However, none of these techniques can fully characterize the composition of the atherosclerotic plaque in the vessel wall and therefore are incapable of identifying the vulnerable plaques. High-resolution, multi-contrast, magnetic resonance (MR) can non-invasively image vulnerable plaques and characterize plaques in terms of lipid and fibrous content and identify the presence of thrombus or calcium. Application of MR imaging opens up whole new areas for diagnosis, prevention, and treatment of atherosclerosis.
Shunk, Kendrick; Atalar, Ergin; Lima, Joao
doi: 10.1023/A:1010667617641pmid: 11587451
The thoracic aortic wall is a common site of atherosclerotic plaque in humans. Tools for serial, non-invasive assessment of these plaques are of value for addressing gaps in our basic understanding of the biology of plaque rupture and its relationship to atherosclerotic disease progression as well as for monitoring response to anti-atherosclerotic interventions in therapeutic clinical trials. Common approaches to assessment of the wall of the thoracic aorta in vivo are limited. Here we discuss some of the challenges and limitations encountered by conventional techniques and review a novel approach, transesophageal MRI (TEMRI). Initial experiences in applying the TEMRI approach to assessment of aortic morphology and pathology are discussed.
Worthley, Stephen; Helft, Gérard; Fayad, Zahi; Fuster, Valentin; Rodriguez, Oswaldo; Zaman, Azfar; Badimon, Juan
doi: 10.1023/A:1010688122184pmid: 11587453
Background: High resolution magnetic resonance (MR) imaging of the coronary artery wall in vivo has been limited by the cardiac and respiratory motion, flow artifacts as well as the relatively small size of the coronary arteries. We sought to validate in vivo black blood MR imaging of the coronary artery wall using a double inversion recovery fast spin echo MR imaging sequence with limited breath-holding and cardiac gating for suppression of motion artifacts by comparison with ex vivo MR imaging. Methods: Yorkshire albino swine (n = 6) were used in this study and coronary lesions were induced with balloon angioplasty. Four weeks after balloon injury of the coronary arteries MR imaging of the coronary artery lesions was performed. High resolution in vivo and ex vivo images of the coronary artery wall and lesions were obtained using a double inversion recovery fast spin echo sequence in a 1.5 T MR system. There was a statistically significant agreement (p < 0.0001) between measurements of vessel wall area (r = 0.87, slope = 0.87) and maximal wall thickness (r = 0.84, slope = 0.88) from in vivo and ex vivo MR images of the coronary arteries. The mean differences between in vivo and ex vivo measurements were 0.56 ± 1.98 mm2 for vessel wall area and 0.02 ± 0.36 mm for maximal wall thickness. Conclusions: Using breath-holding and cardiac gating, it is possible to perform high resolution MR imaging of the coronary artery wall in vivo with good suppression of motion artifacts with a double inversion recovery fast spin echo black blood imaging sequence.
Becker, Christoph; Schoepf, U.; Reiser, Maximilian
doi: 10.1023/A:1010652606254pmid: 11587454
Detection of coronary artery calcifications with slice by slice prospective ECG triggering is feasible with electron beam CT as well as with single and multi-row-detector CT (MDCT). The radiation exposure to the patient to obtain comparable image quality is similar for all three modalities utilizing this prospective acquisition technique.
Carr, J.; Danitschek, James; Goff, David; Crouse, John; D'Agostino, Ralph; Chen, Michael; Burke, Gregory
doi: 10.1023/A:1010604724001pmid: 11587455
Current generation Helical Computed Tomography, when coupled with cardiac gating can be used to measure coronary vascular calcium. In this article we review the development of retrospectively gated helical computed tomography on a single slice HCT system and its relation to electron beam CT. The impact of heart rate on selection of helical pitch for the creation of a diastolic image set is detailed, as well as, scanning and post-processing techniques are discussed. The development and initial experience of cardiac gating with multidetector CT systems is presented.
Greenberg, S.; Eshaghpour, Eshagh
doi: 10.1023/A:1010664925818pmid: 11587456
Background: Tetralogy of Fallot repairs invariably result in pulmonary regurgitation with the long term sequelae of ventricular dilatation and dysfunction. Objective: The purpose of this study is to correlate pulmonary flow parameters with right ventricular size and function. Materials and methods: Pulmonary artery velocity was mapped by magnetic resonance flow analysis in seven children with pulmonary regurgitation following tetralogy of Fallot repair. Right and left ventricular volumes were determined by Simpson's rule from double oblique cine gradient echo images of the heart. The ejection fraction was calculated for each ventricle. Right ventricular enlargement was normalized for patient size by calculating the ratios of right ventricle end diastolic and end systolic volumes to the left ventricle end diastolic and end systolic volumes respectively (EDV RV:LV and ESV RV:LV). The maximum pulmonary artery antegrade and retrograde velocities and the ratio of the time for antegrade to regurgitant flow were compared to ventricular function and volume measurements by regression analysis. Results: A significant linear relationship between the maximum regurgitant pulmonary artery velocity and EDV RV:LV was identified (r 2 = 0.82). Conclusion: An elevated maximum pulmonary regurgitant velocity correlated well with the degree of right ventricular enlargement in patients following tetralogy of Fallot repair. If the results are verified by a larger study, the maximum pulmonary regurgitant velocity may be substituted for the more cumbersome direct measurement of right ventricular size.
doi: 10.1023/A:1010669009889pmid: 11587457
Conventional echocardiography and its representation of the heart in a two-dimensional format only provide partial information about cardiac function. Real-time three-dimensional echocardiography is a recently developed technique based on the design of an ultrasound transducer with a matrix array that instantaneously acquires the image contained in a pyramidal volume. The simultaneous display of multiple tomographic images allows the anatomically correct examination of any structure contained within the volumetric image. Software and technologies based on high performance computers designed for graphic handling of three-dimensional images permit the rapid mapping of the volumetric image and provide possibilities beyond those of the echograph. Using this methodology, it is possible to simultaneously visualize multiple superimposed planes in an interactive manner. Real-time three-dimensional echocardiography also allows a quantitative assessment of cardiac volumes, ventricular mass, and myocardium with contraction and/or perfusion abnormalities. This technique thus expands the abilities of non-invasive cardiology and may open new doors for the evaluation of cardiac disease.
Koch, Jens-Albrecht; Poll, Ludger; Godehardt, Erhard; Korbmacher, Bernhard; Jung, Gregor; Mödder, Ulrich
doi: 10.1023/A:1010621126727pmid: 11587458
Purpose: To determine the accuracy of a 1.0 T MR system with a standard gradient system for quantification of left and right ventricular volumes. A porcine heart model in vitro was used. Methods: In eight explanted porcine hearts the atria were removed and the aorta and the pulmonary truncus were cannulated. Defined volumes were injected into the ventricles. Magnetic resonance imaging (MRI): FFE-EPI (Multishot EPI) was used. Papillary muscles and trabeculae were excluded. True volumes and MR measurements were analysed separately for both ventricles and by both investigators. Results: The correlation of the true volumes and MR measurements was > 0.99. MRI was found to be investigator independent in assessing right and left ventricular volumes in vitro. Conclusions: MRI at 1.0 T using standard equipment can be used to quantitate cardiac ventricular volumes in vitro with high accuracy.
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