Invasive validation of a new oscillometric device (Arteriograph) for measuring augmentation index, central blood pressure and aortic pulse wave velocity

Background The importance of measuring aortic pulse wave velocity (PWVao), aortic augmentation index (Aix) and central systolic blood pressure (SBPao) has been shown under different clinical conditions; however, information on these parameters is hard to obtain. The aim of this study was to evaluate the accuracy of a new, easily applicable oscillometric device (Arteriograph), determining these parameters simultaneously, against invasive measurements. Methods Aortic Aix, SBPao and PWVao were measured invasively during cardiac catheterization in 16, 55 and 22 cases, respectively, and compared with the values measured by the Arteriograph. Results We found strong correlation between the invasively measured aortic Aix and the oscillometrically measured brachial Aix on either beat-to-beat or mean value per patient basis (r=0.9, P<0.001; r=0.94, P<0.001), which allowed the noninvasive calculation of the aortic Aix without using generalized transfer function. Similarly strong correlation (r=0.95, P<0.001) was found between the invasively measured and the noninvasively calculated central SBPao; furthermore, the BHS assessment of the paired differences fulfilled the 'B' grading. The PWVao values measured invasively and by Arteriograph were 9.41 +/- 1.8 m/s and 9.46 +/- 1.8 m/s, respectively (mean +/- SD); furthermore, the Pearson's correlation was 0.91 (P<0.001). The limits of agreement were 11.4% for aortic Aix and 1.59 m/s for PWVao. Conclusion Aix, SBPao and PWVao, measured oscillometrically, showed strong correlation with the invasively obtained values. The observed limits of agreement are encouragingly low for accepting the method for clinical use. Our results suggest that the PWVao values, measured by Arteriograph, are close to the true aortic PWV, determined invasively. J Hypertens 28: 2068-2075 (C) 2010 Wolters Kluwer Health vertical bar Lippincott Williams & Wilkins

In Vitro Longitudinal Relaxivity Profile of Gd(ABE-DTTA), an Investigational Magnetic Resonance Imaging Contrast Agent.

MRI contrast agents (CA) whose contrast enhancement remains relatively high even at the higher end of the magnetic field strength range would be desirable. The purpose of this work was to demonstrate such a desired magnetic field dependency of the longitudinal relaxivity for an experimental MRI CA, Gd(ABE-DTTA).The relaxivity of 0.5mM and 1mM Gd(ABE-DTTA) was measured by Nuclear Magnetic Relaxation Dispersion (NMRD) in the range of 0.0002 to 1T. Two MRI and five NMR instruments were used to cover the range between 1.5 to 20T. Parallel measurement of a Gd-DTPA sample was performed throughout as reference. All measurements were carried out at 37°C and pH 7.4.The relaxivity values of 0.5mM and 1mM Gd(ABE-DTTA) measured at 1.5, 3, and 7T, within the presently clinically relevant magnetic field range, were 15.3, 11.8, 12.4 s-1mM-1 and 18.1, 16.7, and 13.5 s-1mM-1, respectively. The control 4 mM Gd-DTPA relaxivities at the same magnetic fields were 3.6, 3.3, and 3.0 s-1mM-1, respectively.The longitudinal relaxivity of Gd(ABE-DTTA) measured within the presently clinically relevant field range is three to five times higher than that of most commercially available agents. Thus, Gd(ABE-DTTA) could be a practical choice at any field strength currently used in clinical imaging including those at the higher end

List of the MRI and NMR equipment used in our studies.

<p>List of the MRI and NMR equipment used in our studies.</p

<i>In Vitro</i> Longitudinal Relaxivity Profile of Gd(ABE-DTTA), an Investigational Magnetic Resonance Imaging Contrast Agent

<div><p>Purpose</p><p>MRI contrast agents (CA) whose contrast enhancement remains relatively high even at the higher end of the magnetic field strength range would be desirable. The purpose of this work was to demonstrate such a desired magnetic field dependency of the longitudinal relaxivity for an experimental MRI CA, Gd(ABE-DTTA).</p><p>Materials and Methods</p><p>The relaxivity of 0.5mM and 1mM Gd(ABE-DTTA) was measured by Nuclear Magnetic Relaxation Dispersion (NMRD) in the range of 0.0002 to 1T. Two MRI and five NMR instruments were used to cover the range between 1.5 to 20T. Parallel measurement of a Gd-DTPA sample was performed throughout as reference. All measurements were carried out at 37°C and pH 7.4.</p><p>Results</p><p>The relaxivity values of 0.5mM and 1mM Gd(ABE-DTTA) measured at 1.5, 3, and 7T, within the presently clinically relevant magnetic field range, were 15.3, 11.8, 12.4 s^-1mM^-1 and 18.1, 16.7, and 13.5 s^-1mM^-1, respectively. The control 4 mM Gd-DTPA relaxivities at the same magnetic fields were 3.6, 3.3, and 3.0 s^-1mM^-1, respectively.</p><p>Conclusions</p><p>The longitudinal relaxivity of Gd(ABE-DTTA) measured within the presently clinically relevant field range is three to five times higher than that of most commercially available agents. Thus, Gd(ABE-DTTA) could be a practical choice at any field strength currently used in clinical imaging including those at the higher end.</p></div