Ronnie Wirestam1, Emelie Lind2, André Ahlgren2, Freddy Ståhlberg2,3, Linda Knutsson2. 1. Department of Medical Radiation Physics, University Hospital, Lund University, SE-22185, Lund, Sweden. ronnie.wirestam@med.lu.se. 2. Department of Medical Radiation Physics, University Hospital, Lund University, SE-22185, Lund, Sweden. 3. Department of Diagnostic Radiology, University Hospital, Lund University, SE-22185, Lund, Sweden.
Abstract
OBJECTIVES: Contrast agent (CA) relaxivities are generally not well established in vivo, and the relationship between frequency/phase shift and magnetic susceptibility might be a useful alternative for CA quantification. MATERIALS AND METHODS: Twenty volunteers (25-84 years old) were investigated using test-retest pre-bolus dynamic susceptibility-contrast (DSC) magnetic resonance imaging (MRI). The pre-bolus phase-based venous output function (VOF) time integral was used for arterial input function (AIF) rescaling. Resulting cerebral blood flow (CBF) data for grey matter (GM) were compared with pseudo-continuous arterial spin labelling (ASL). During the main bolus CA passage, the apparent spatial shift (pixel shift) of the superior sagittal sinus (seen in single-shot echo-planar imaging (EPI)) was converted to CA concentration and compared with conventional ΔR2*-based data and with a predicted phase-based VOF from the pre-bolus experiment. RESULTS: The phase-based pre-bolus VOF resulted in a reasonable inter-individual GM CBF variability (coefficient of variation 28 %). Comparison with ASL CBF values implied a tissue R2*-relaxivity of 32 mM-1 s-1. Pixel-shift data at low concentrations (data not available at peak concentrations) were in reasonable agreement with the predicted phase-based VOF. CONCLUSION: Susceptibility-induced phase shifts and pixel shifts are potentially useful for large-vein CA quantification. Previous predictions of a higher R2*-relaxivity in tissue than in blood were supported.
OBJECTIVES: Contrast agent (CA) relaxivities are generally not well established in vivo, and the relationship between frequency/phase shift and magnetic susceptibility might be a useful alternative for CA quantification. MATERIALS AND METHODS: Twenty volunteers (25-84 years old) were investigated using test-retest pre-bolus dynamic susceptibility-contrast (DSC) magnetic resonance imaging (MRI). The pre-bolus phase-based venous output function (VOF) time integral was used for arterial input function (AIF) rescaling. Resulting cerebral blood flow (CBF) data for grey matter (GM) were compared with pseudo-continuous arterial spin labelling (ASL). During the main bolus CA passage, the apparent spatial shift (pixel shift) of the superior sagittal sinus (seen in single-shot echo-planar imaging (EPI)) was converted to CA concentration and compared with conventional ΔR2*-based data and with a predicted phase-based VOF from the pre-bolus experiment. RESULTS: The phase-based pre-bolus VOF resulted in a reasonable inter-individual GM CBF variability (coefficient of variation 28 %). Comparison with ASL CBF values implied a tissue R2*-relaxivity of 32 mM-1 s-1. Pixel-shift data at low concentrations (data not available at peak concentrations) were in reasonable agreement with the predicted phase-based VOF. CONCLUSION: Susceptibility-induced phase shifts and pixel shifts are potentially useful for large-vein CA quantification. Previous predictions of a higher R2*-relaxivity in tissue than in blood were supported.
Authors: Emelie Lindgren; Ronnie Wirestam; Karin Markenroth Bloch; André Ahlgren; Matthias J P van Osch; Danielle van Westen; Yulia Surova; Freddy Ståhlberg; Linda Knutsson Journal: MAGMA Date: 2014-02-26 Impact factor: 2.310
Authors: Thomas E Conturo; Erbil Akbudak; Melanie S Kotys; Maison L Chen; Steve J Chun; Raymond M Hsu; Caitlin C Sweeney; Joanne Markham Journal: J Magn Reson Imaging Date: 2005-12 Impact factor: 4.813
Authors: Linda Knutsson; Xiang Xu; Freddy Ståhlberg; Peter B Barker; Emelie Lind; Pia C Sundgren; Peter C M van Zijl; Ronnie Wirestam Journal: Tomography Date: 2017-06