Irene K Mikkelsen

Publications (2)5.93 Total impact

• Article: Analysis of partial volume effects on arterial input functions using gradient echo: a simulation study.

  Birgitte F Kjølby, Irene K Mikkelsen, Michael Pedersen, Leif Østergaard, Valerij G Kiselev
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  ABSTRACT: Absolute blood flow and blood volume measurements using perfusion weighted MRI require an accurately measured arterial input function (AIF). Because of limited spatial resolution of MR images, AIF voxels cannot be placed completely within a feeding artery. We present a two-compartment model of an AIF voxel including the relaxation properties of blood and tissue. Artery orientations parallel and perpendicular to the main magnetic field were investigated and AIF voxels were modeled to either include or be situated close to a large artery. The impact of partial volume effects on quantitative perfusion metrics was investigated for the gradient echo pulse sequence at 1.5 T and 3.0 T. It is shown that the tissue contribution broadens and introduces fluctuations in the AIF. Furthermore, partial volume effects bias perfusion metrics in a nonlinear fashion, compromising quantitative perfusion estimates and profoundly effecting local AIF selection.
  Magnetic Resonance in Medicine 05/2009; 61(6):1300-9. · 2.96 Impact Factor
• Article: Absolute quantification of cerebral blood flow in neurologically normal volunteers: dynamic-susceptibility contrast MRI-perfusion compared with computed tomography (CT)-perfusion.

  Doerthe Ziegelitz, Göran Starck, Irene K Mikkelsen, Mats Tullberg, Mikael Edsbagge, Carsten Wikkelsö, Eva Forssell-Aronson, Stig Holtås, Linda Knutsson
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  ABSTRACT: To improve the reproducibility of arterial input function (AIF) registration and absolute cerebral blood flow (CBF) quantification in dynamic-susceptibility MRI-perfusion (MRP) at 1.5T, we rescaled the AIF by use of a venous output function (VOF). We compared CBF estimates of 20 healthy, elderly volunteers, obtained by computed tomography (CT)-perfusion (CTP) and MRP on two consecutive days. MRP, calculated without the AIF correction, did not result in any significant correlation with CTP. The rescaled MRP showed fair to moderate correlation with CTP for the central gray matter (GM) and the whole brain. Our results indicate that the method used for correction of partial volume effects (PVEs) improves MRP experiments by reducing AIF-introduced variance at 1.5T.
  Magnetic Resonance in Medicine 03/2009; 62(1):56-65. · 2.96 Impact Factor