Myocardial Tagging Techniques Research Articles

A comparison of cardiac motion analysis software packages: application to left ventricular deformation analysis in healthy subjects

Background Feature tracking (FT) software packages measure myocardial wall motion deformation parameters through the cardiac cycle. Myocardial tagging technique is currently considered the gold standard for myocardial deformation measurements. This study compares 2 FT-software packages with a tagging software package and investigates the differences in strain deformation parameters measured in healthy subjects.

In vivo validation of an ultra-high field, high temporal resolution myocardial tagging technique for assessment of diastolic function in mice

Background Heart failure with preserved ejection fraction accounts for approximately half of all heart failure cases and is associated with similar morbidity and mortality. Although abnormalities of diastolic function are felt to play an important role, no specific treatments have been identified for this common condition, primarily because of poor understanding of its pathophysiology. Despite development of several murine models of this disease, accurate non-invasive assessment of diastolic function has been challenging. Echocardiographic measurements have been limited by small heart sizes, rapid ventricular rates and high inter-observer variability. The aim of this study was to assess the ability of ultra-high field, high temporal resolution CMR tagging to assess diastolic function in mice, compared to the gold-standard technique of invasive pressure-volume loop analysis.

Cardiac deformation analysis from orthogonal CSPAMM (OCSPAMM) tagged MRI

Background Magnetic resonance imaging (MRI) is a highly advanced and sophisticated imaging modality for cardiac motion assessment and quantitative analysis. The myocardial tagging techniques have seen wide applications for cardiac deformation analysis (see [1-4] for example). Among different image post-processing techniques, frequency-based methods have played an important role in analysis of heart displacement from tagged MRI images [5,6]. In this abstract, we apply the SinMod technique to data from a new tagging pulse sequence which we have recently developed called Orthogonal CSPAMM (OCSPAMM) [7].

Ventricular Restraint Prevents Infarct Expansion and Improves Borderzone Function After Myocardial Infarction: A Study Using Magnetic Resonance Imaging, Three-Dimensional Surface Modeling, and Myocardial Tagging

Infarct expansion is associated with impaired borderzone function, adverse remodeling, and poor long-term prognosis. We hypothesized that left ventricular restraint early after myocardial infarction limits infarct expansion, preserves borderzone function, and reduces remodeling. We used an ovine model as well as high spatial and temporal resolution cardiac magnetic resonance imaging to quantify total and infarcted left ventricular epicardial surface area at baseline and 1 week and 12 weeks after anterior wall infarction in 10 animals. Five animals were randomly assigned to treatment with left ventricular restraint (Acorn cardiac support device) 1 week after infarction. Five animals were untreated controls. Total left ventricular surface area was measured by importing the end-diastolic magnetic resonance imaging-derived epicardial contours into custom software, which creates a three-dimensional surface from the two-dimensional magnetic resonance imaging contours. Infarct area was calculated from magnetic resonance imaging-detectable titanium markers placed at the infarct border. Borderzone radial and circumferential strains during systole were also assessed using myocardial tagging techniques as a measure of contractile function. The infarct area 1 week after infarction was 1,177 +/- 386 mm(2) in the control group and 1,124 +/- 427 mm(2) in the cardiac support device group. After 12 weeks, infarct area was 3,666 +/- 1,013 mm(2) in the control group and 1,227 +/- 301 mm(2) in the cardiac support device group. Borderzone systolic radial strain decreased from 12.6% +/- 0.77% to 3.6% +/- 0.3% after infarction in the control group and 13.7% +/- 0.87% to 4.7% +/- 0.3% in the cardiac support device group. At 12 weeks after infarction, radial strain was 3.4% +/- 0.5% in the control group and 6.7% +/- 0.4% in the cardiac support device group. Early postinfarction left ventricular restraint limits infarct expansion and improves borderzone contractile function.

Strain and Strain Rate Echocardiography

Myocardial function is eventually determined by the shortening and lengthening of myocardium, i.e., myocardial deformation or strain. The exact and direct measure of myocardial deformation has been dependent on the in vitro analysis of myocardial length. This is not an ideal physiological approach due to the change of the surrounding environment, and the process is rather tedious. Thus, this in vitro approach is primarily a research tool. Thanks to recently developed imaging techniques, regional myocardial deformation can now be measured. Using the myocardial tagging technique, one can measure myocardial strain with high accuracy. Currently, this is used as the clinical standard for the noninvasive evaluation of regional function.1 However, due to cost and long time needed for off-line analysis, myocardial tagging by MRI is not routinely utilized for clinical purposes. In 1998 and then in 2000, Heidelm2 and Urheim,3 et al., reported that based on myocardial velocities by tissue Doppler imaging (TOI), the rate of myocardial deformation (strain rate or myocardial velocity gradient) can be calculated. In validation studies, Doppler-derived strain accurately reflected regional myocardial shortening and lengthening when compared to measurements by sonometric crystals. Since then, strain rate imaging (SRI) has been examined in animal and clinical studies for the assessment of cardiac function.

Diagnosis of coronary artery disease with dobutamine–stress MRI

Dobutamine-stress cardiovascular magnetic resonance (CMR) is a new diagnostic tool for the non-invasive detection of coronary artery disease. Technological advances in CMR have evolved this technique to an adequate alternative to the standard cardiac stress tests. Its high reproducibility and excellent image quality of the anatomical features of the left ventricle and left ventricular function at rest and during stress make it an ideal technique for the comprehensive evaluation of patients with suspected coronary artery disease. Besides its ability to detect myocardial ischemia, CMR has proved to be diagnostic for myocardial viability as well. A recent technical refinement in CMR using myocardial tagging has improved the diagnostic accuracy for myocardial ischemia even further. Dobutamine-stress CMR is used to identify wall motion abnormalities of the left ventricle in patients with proven or suspected coronary artery disease [1-4]. Dobutamine-stress CMR has emerged as a highly accurate and safe diagnostic modality [1-4]. Recently, the use of high-dose dobutamine CMR in combination with the myocardial tagging technique has been reported, with excellent diagnostic results. The use of this new technique and the clinical applications are discussed.

Single breath-hold slice-following CSPAMM myocardial tagging.

Myocardial tagging has shown to be a useful magnetic resonance modality for the assessment and quantification of local myocardial function. Many myocardial tagging techniques suffer from a rapid fading of the tags, restricting their application mainly to systolic phases of the cardiac cycle. However, left ventricular diastolic dysfunction has been increasingly appreciated as a major cause of heart failure. Subtraction based slice-following CSPAMM myocardial tagging has shown to overcome limitations such as fading of the tags. Remaining impediments to this technique, however, are extensive scanning times (approximately 10 min), the requirement of repeated breath-holds using a coached breathing pattern, and the enhanced sensitivity to artifacts related to poor patient compliance or inconsistent depths of end-expiratory breath-holds. We therefore propose a combination of slice-following CSPAMM myocardial tagging with a segmented EPI imaging sequence. Together with an optimized RF excitation scheme, this enables to acquire as many as 20 systolic and diastolic grid-tagged images per cardiac cycle with a high tagging contrast during a short period of sustained respiration.

Single breath-hold slice-following CSPAMM myocardial tagging

Myocardial tagging has shown to be a useful magnetic resonance modality for the assessment and quantification of local myocardial function. Many myocardial tagging techniques suffer from a rapid fading of the tags, restricting their application mainly to systolic phases of the cardiac cycle. However, left ventricular diastolic dysfunction has been increasingly appreciated as a major cause of heart failure. Subtraction based slice-following CSPAMM myocardial tagging has shown to overcome limitations such as fading of the tags. Remaining impediments to this technique, however, are extensive scanning times (∼10 min), the requirement of repeated breath-holds using a coached breathing pattern, and the enhanced sensitivity to artifacts related to poor patient compliance or inconsistent depths of end-expiratory breath-holds. We therefore propose a combination of slice-following CSPAMM myocardial tagging with a segmented EPI imaging sequence. Together with an optimized RF excitation scheme, this enables to acquire as many as 20 systolic and diastolic grid-tagged images per cardiac cycle with a high tagging contrast during a short period of sustained respiration.

Evaluation of cardiac function with magnetic resonance imaging

A large body of evidence has accumulated to substantiate the accuracy of functional MR measurements of both ventricles. Because of good accuracy and superior reproducibility, MR imaging may be considered the gold standard for in vivo quantification of left and right ventricular ejection fraction, myocardial mass, and wall stress. New prospects for functional MR imaging include determination of the end-systolic volume-pressure relation as an index of myocardial contractility. The ability of MR imaging to detect wall motion disturbances may be enhanced further by combining myocardial tagging techniques with finite element analysis. Conventional MR imaging is limited by long examination times, but recent ultrafast modifications of echo-planar imaging allow completion of a functional heart study within seconds. Implementation of ultrafast MR imaging will greatly increase the usefulness of MR imaging for routine evaluation of cardiac function.

True myocardial motion tracking

Myocardial tagging is a powerful tool for the assessment of in-plane cardiac motion. However, for previous myocardial tagging techniques, the imaged slice is fixed with respect to the magnet coordinate system. Thus, images acquired at different heart phases do not always represent the same slice of the myocardium. A new myocardial tagging technique is presented, which takes the through-plane motion into consideration. It involves tagging of the desired myocardial slice and applying a subtraction imaging technique to image just that part of the myocardium. The examination time can be reduced considerably by the acquisition of two one-dimensionally tagged images. To increase the signal-to-noise ratio especially at later heart phases, variable imaging RF excitation flip angles are applied. To reduce motion artifacts a repetitive breathhold scheme was applied. In vivo results demonstrate that the tags can be accurately tracked within the entire heart period with a temporal resolution of 35 ms, even at a top basal level of the heart and right ventricle.

Normal Left Ventricular Wall Motion Measured with Two-Dimensional Myocardial Tagging

Using a myocardial tagging technique, normal left ventricular wall motion was studied in 3 true short axis views and a double oblique 4-chamber view in 14 and 11 volunteers, respectively. Three orthogonal directions of left ventricular motion were observed throughout the systole; a concentric contraction towards the center of the left ventricle, a motion of the base of the heart towards the apex, and a rotation of the left ventricle around its long axis. The direction of left ventricular rotation changed from early systole to late systole. The base and middle levels of the left ventricle rotated counterclockwise (CCW) at early systole and clockwise (CW) at late systole, whereas the apex of the heart rotated CW at early systole and CCW at late systole. The different directions of the rotation of base and apex resulted in a myocardial twisting that changed direction from early to late systole. We conclude that MR imaging with myocardial tagging is a method that can be used to study normal left ventricular wall motion, and that is promising for future use in patient groups.