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MR Tagging (mr + tagging)
Selected AbstractsStrain-encoded (SENC) magnetic resonance imaging to evaluate regional heterogeneity of myocardial strain in healthy volunteers: Comparison with conventional taggingJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 1 2009Mirja Neizel MD Abstract Purpose To evaluate the ability of strain-encoded (SENC) magnetic resonance imaging (MRI) for regional systolic and diastolic strain analysis of the myocardium in healthy volunteers. Materials and Methods Circumferential and longitudinal peak systolic strain values of 75 healthy volunteers (35 women and 40 men, mean age 44 ± 12 years) were measured using SENC at 1.5T. MR tagging was used as the reference standard for measuring regional function. Diastolic function was assessed in the 10 youngest (24 ± 8 years) and 10 oldest (62 ± 5 years) subjects. Results Peak strain values assessed with SENC were comparable to those obtained by MR tagging, showing narrow limits of agreement (limits of agreement ,5.6% to 8.1%). Regional heterogeneity was observed between different segments of the left ventricle (LV) by both techniques (P < 0.001). Longitudinal strain obtained by SENC was also heterogenous (P < 0.001). Interestingly, no age- or gender-specific differences in peak systolic strain were observed, whereas the peak rate of relaxation of circumferential strain rate was decreased in the older group. Conclusion SENC is a reliable tool for accurate and objective quantification of regional myocardial systolic as well as diastolic function. In agreement with tagged MRI, SENC detected slightly heterogeneous myocardial strain within LV segments. J. Magn. Reson. Imaging 2009;29:99,105. © 2008 Wiley-Liss, Inc. [source] Real-time single-heartbeat fast strain-encoded imaging of right ventricular regional function: Normal versus chronic pulmonary hypertension,MAGNETIC RESONANCE IN MEDICINE, Issue 1 2010Monda L. Shehata Abstract Patients with pulmonary hypertension and suspected right ventricular (RV) dysfunction often have dyspnea at rest, making reliable assessment of RV function using traditional breath-holding methods difficult to perform. Using single-heartbeat fast strain encoding (Fast-SENC) imaging, peak systolic RV circumferential and longitudinal strains were measured in 11 healthy volunteers and 11 pulmonary hypertension patients. Fast-SENC RV longitudinal strain and circumferential strain measurements were compared to conventional SENC and MR tagging, respectively. Fast-SENC circumferential and longitudinal RV shortening correlated closely with SENC measurements (r = 0.86, r = 0.90, P < 0.001 for all). Circumferential strain, by conventional tagging, showed moderate correlation with Fast-SENC in pulmonary hypertension patients only (r = 0.5, P = 0.003). A nonuniform pattern of RV circumferential shortening was depicted in both groups. Peak systolic circumferential strain was significantly reduced at the basal RV in pulmonary hypertension patients (,18.06 ± 3.3 versus ,21.9 ± 1.9, P < 0.01) compared to normal individuals, while peak systolic longitudinal strain was significantly reduced at all levels (P < 0.01 for all). Fast-SENC is a feasible and reliable technique for rapid quantification of RV regional function in a single-heartbeat acquisition. Information derived from Fast-SENC allows characterization of RV regional function in normal individuals and in pulmonary hypertension patients. Magn Reson Med, 2010. © 2010 Wiley-Liss, Inc. [source] Assessment of regional systolic and diastolic dysfunction in familial hypertrophic cardiomyopathy using MR tagging,MAGNETIC RESONANCE IN MEDICINE, Issue 3 2003Daniel B. Ennis Abstract Diastolic and systolic left ventricular (LV) dysfunction often significantly contribute to disabling symptoms in familial hypertrophic cardiomyopathy (FHC). This study compares regional LV function (midwall circumferential strain) during systole and diastole in eight FHC patients and six normal volunteers (NVs) using MR tagging. A prospectively-gated fast gradient-echo sequence with an echo-train readout was modified to support complementary spatial modulation of magnetization (CSPAMM) tagging and full cardiac cycle data acquisition using the cardiac phase to order reconstruction (CAPTOR), thus providing tag persistence and data acquisition during the entire cardiac cycle. Total systolic strains in FHC patients were significantly reduced in septal and inferior regions (both P < 0.01). Early-diastolic strain rates were reduced in all regions of the FHC group (all P < 0.03). The combination of CSPAMM and CAPTOR allows regional indices of myocardial function to be quantified throughout the cardiac cycle. This technique reveals regional differences in systolic and diastolic impairment in FHC patients. Magn Reson Med 50:638,642, 2003. Published 2003 Wiley-Liss, Inc. [source] Pulse-wave velocity measured in one heartbeat using MR taggingMAGNETIC RESONANCE IN MEDICINE, Issue 1 2002Christopher K. Macgowan Abstract A noninvasive method for measuring the aortic pulse-wave velocity (PWV) in a single heartbeat is introduced. The method sinusoidally tags a column of blood within the vessel, and rapidly acquires a series of 1D projections of the tags as they move (in practice, 64 projections at 4-ms intervals). From these projections, the relative motion of blood at different positions along the vessel is measured. The PWV is obtained by fitting a mathematical model of blood flow to the tag trajectories. Tests of this method in a pulsatile flow phantom are presented using latex and polyurethane tubes. The PWV measured in these tubes was (mean ± standard deviation) 4.4 ± 0.5 m/s and 2.3 ± 0.2 m/s, respectively. The distensibility of each tube was calculated from the PWV (latex = (7 ± 2) 10,3 mm Hg,1, poly. = (25 ± 4) 10,3mmHg,1) and found to agree within error with distensibility measurements based on the change of tube area with pressure (latex = (6.3 ± 0.3) 10,3mmHg,1, poly. = (27 ± 1) 10,3 mmHg,1). To test its feasibility, the PWV measurement was applied to four normal volunteers. The measured PWV values were 3.9 ± 0.8 m/s, 3.6 ± 0.9 m/s, 3.9 ± 0.5 m/s, and 5.3 ± 0.8 m/s. By acquiring an independent PWV measurement each heartbeat, errors introduced by arrhythmia and trigger variability appear to be avoided with this method. Magn Reson Med 48:115,121, 2002. © 2002 Wiley-Liss, Inc. [source] Feasibility of complementary spatial modulation of magnetization tagging in the rat heart after manganese injectionNMR IN BIOMEDICINE, Issue 1 2008J.-N. Hyacinthe Abstract It has been shown that manganese-enhanced MRI (MEMRI) can safely depict the myocardial area at risk in models of coronary occlusion,reperfusion for at least 2,h after reperfusion. To achieve this, a solution of MnCl2 is injected during coronary occlusion. In this model, the regional function quantification deficit of the stunning phase cannot be assessed before contrast injection using MR tagging. The relaxation effects of manganese (which remains in normal cardiac myocytes for several hours) may alter the tags by increasing tag fading and hence the quality of strain measurement. Therefore, we evaluated the feasibility of cardiac MR tagging after manganese injection in normal rats. Six normal Sprague,Dawley rats were imaged in vivo using complementary spatial modulation of magnetization (C-SPAMM) at 1.5,T, before and 15,min after intraperitoneal injection of MnCl2 solution (,17.5,µmol,kg,1). The contrast-to-noise ratio of the tag pattern increased significantly (P,<,0.001) after injection and remained comparable to the control scan in spite of the higher myocardial relaxation rate caused by the presence of manganese. The measurements of circumferential strain obtained from harmonic phase imaging analysis of the tagged images after MnCl2 injection did not differ significantly from the measurements before injection in the endocardial, mid-wall, and epicardial regions. In particular, the transmural strain gradient was preserved. Thus, our study suggests that MR tagging could be used in combination with MEMRI to study the acute phase of coronary artery disease. Copyright © 2007 John Wiley & Sons, Ltd. [source] | ||||||||||