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      Influence of slice thickness on MR flow quantification in turbulent jets

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      1 , , 2 , 1
      Journal of Cardiovascular Magnetic Resonance
      BioMed Central
      2011 SCMR/Euro CMR Joint Scientific Sessions
      3-6 February 2011

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          Abstract

          Introduction Magnetic Resonance (MR) based flow quantification is of high interest in several cardiac diseases, e.g. valvular stenosis. However, accurate results remain challenging in several conditions. Recently, some contributors could be defined including echo time [1] (TE) and background phase errors [2]. We investigated the influence of slice thickness on flow quantification in turbulent flow. Methods A flow phantom was developed, which disposes of an adjustable pump and a model similar to the shape of a human aorta (Figure 1). To imitate an aortic stenosis, a Perspex plate with a borehole (D=11.5mm; A≈1cm2) was introduced. Retrospectively gated phase contrast cine imaging (in-plane resolution 1.8x1.3mm) was applied to obtain flow data from an Avanto 1.5T MR system (Siemens Healthcare Sector, Erlangen, Germany). Tested sequence settings were a) RF pulse length=1000us, maximum flow encoding gradient strength=10mT/m, TE=3.1ms; b) RF pulse length=400us, maximum flow encoding gradient strength=20mT/m, TE=2.2ms; c) RF pulse length=400us, maximum flow encoding gradient strength=20mT/m, TE=3.1ms. Tested slice thicknesses ranged from 4.5mm to 10mm. Steady but turbulent flow (300ml/s) was measured at 2.5cm behind the stenosis (Figure 1b) with 20 calculated cardiac phases (yielding 20 flow values). Flow quantification was done using CMR42 (Circle CVi, Calgary, Canada). Average flow deviation and its standard deviation were calculated. Figure 1 Slice positioning Results Figure 2 shows the measured flow deviations for the tested settings (a-c) over the different slice thicknesses. The maximum flow deviation was measured in case of an RF pulse of 1000us duration and a maximum flow encoding gradient strength of 20mT/m. Increasing TE did not show additional flow errors. Measurements with slice thicknesses below 6mm were found to be higher than with slice thicknesses above. Figure 2 Flow deviation dependent on the slice thickness with a) TE=3.1ms (red), b) TE=2.2ms (black), c) TE=3.1ms (blue). Maximum flow underestimation was found at a) (-27%, ST=7.5mm), maximum overestimation was found at b) (9%, ST=4.5mm) Conclusion Our results show that slice thickness influences flow quantification in the presence of turbulent flow in certain sequence configurations. Decreasing the time of flow encoding by increasing the flow encoding gradient strength seems sufficient to mitigate flow errors for all slice thicknesses. Further investigations have to be conducted to explain the impact of the slice thickness on flow quantification in-vivo.

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          Author and article information

          Conference
          J Cardiovasc Magn Reson
          Journal of Cardiovascular Magnetic Resonance
          BioMed Central
          1097-6647
          1532-429X
          2011
          2 February 2011
          : 13
          : Suppl 1
          : P363
          Affiliations
          [1 ]Experimental and Clinical Research Center (ECRC), Charite' - University Medicine Campus Berlin Buch, Berlin, Germany
          [2 ]Siemens Healthcare Sector, Erlangen, Germany
          Article
          1532-429X-13-S1-P363
          10.1186/1532-429X-13-S1-P363
          3106606
          103d77fa-bf88-4ad6-81c1-1f7c181e61a4
          Copyright ©2011 Dieringer et al; licensee BioMed Central Ltd.

          This is an open access article distributed under the terms of the Creative Commons Attribution License ( http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

          2011 SCMR/Euro CMR Joint Scientific Sessions
          Nice, France
          3-6 February 2011
          History
          Categories
          Poster Presentation

          Cardiovascular Medicine
          Cardiovascular Medicine

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