TRADITIONAL POSTER - ismrm

Poster Sessions
DSC Perfusion: Acquisition Methods
Hall B Wednesday 13:30-15:30
1783. Dynamic Susceptibility Contrast Imaging Using a Multi-Echo Spiral Sequence
Nicolas Pannetier 1,2 , Thomas Christen 1,2 , Mohamed Tachrount 1,2 , Benjamin Lemasson 1,3 , Regine Farion 1,2 ,
Sebastien Reyt 1,2 , Nicolas Coquery 1 , Christoph Segebarth 1,2 , Chantal Remy 1,2 , Emmanuel Louis Barbier 1,2
1 Inserm, U836, Grenoble, France; 2 Université Joseph Fourier, Grenoble Institut des Neurosciences, UMR-S836, Grenoble, France;
3 Oncodesign Biotechnology, Dijon, France
To characterize microvasculature, one can perform a DCE-MRI followed by a DSC-MRI experiment. However, estimates from a DSC experiment
performed after a DCE-MRI experiment differ from estimates derived from a single DSC experiment, especially due to different T1. In this study, we
investigate how T1 effect contributes to rCBV estimates in the case of one and two consecutive injections of contrast agent (CA). Thus, we used a multi echo
spiral sequence in a rat glioma model. Results suggest that DSC-MRI performed during a second injection of CA is less sensitive to T1 effects than DSC-
MRI performed during a first injection.
1784. Perfusion Information Obtained by Dynamic Contrast-Enhanced Phase-Shift MRI: Comparison with
Model-Free ASL
Emelie Lindgren 1 , Linda Knutsson 1 , Danielle van Westen 2,3 , Karin Markenroth Bloch 4 , Freddy Ståhlberg 1,3 ,
Ronnie Wirestam 1
1 Department of Medical Radiation Physics, Lund University, Lund, Sweden; 2 Center for Medical Imaging and Physiology, Lund
University Hospital, Lund, Sweden; 3 Department of Diagnostic Radiology, Lund University, Lund, Sweden; 4 Philips Medical
Systems, Lund, Sweden
The phase shift during a contrast-agent bolus passage is assumed to be proportional to the concentration of contrast agent. In this study, phase-shift curves in
tissue and artery were registered and a phase-based perfusion index and grey-matter MTT were calculated. The relationship between the phase-based
perfusion index and ASL CBF estimates showed good linear correlation (r=0.81). The mean grey-matter MTT was 5.4 s, consistent with literature values.
Phase-based absolute quantification of CBF is difficult, but the use of a phase-based perfusion index for rescaling of DSC-MRI results can potentially be of
value to achieve more robust and reproducible DSC-MRI estimates.
1785. T1-Independent Vessel Size Imaging with Multi-Gradient- And Spin-Echo EPI
Heiko Schmiedeskamp 1 , Matus Straka 1 , Diane Jenuleson 2 , Greg Zaharchuk 1 , Roland Bammer 1
1 Lucas Center, Department of Radiology, Stanford University, Stanford, CA, United States; 2 Stanford University Medical Center,
Stanford, CA, United States
Vessel size imaging is a relatively new technique that relates contrast agent-induced changes of transverse relaxation rates, R2 and R2*, to each other to
obtain an index that provides information about the size of vessels within a voxel of interrogation. Ideally, such measurements require the simultaneous
acquisition of multiple gradient-echo (GE) and a spin-echo (SE) signals. However, limiting the acquisition to one GE and SE induces T1-related errors in the
vessel size estimation. This problem can be solved by acquiring multiple GE/SE-signals, from which one can derive T1-independent estimates of R2 and
R2* from before and during contrast-agent passage.
1786. Effects of Blood δR2* Non-Linearity on Absolute Perfusion Quantification Using DSC-MRI:
Comparison with Xe-133 SPECT
Linda Knutsson 1 , Freddy Ståhlberg 1,2 , Ronnie Wirestam 1 , Matthias Johannes Paulus van Osch 3
1 Department of Medical Radiation Physics, Lund University, Lund, Sweden; 2 Department of Diagnostic Radiology, Lund University,
Lund, Sweden; 3 Department of Radiology, Leiden University Medical Center, Leiden, Netherlands
A linear relationship between the δR2* and contrast agent concentration in blood is often assumed, however, calibration measurements in whole blood have
shown that a non-linear relation between δR2* and contrast agent concentration exists. In this evaluation of CBF data, we compared absolute CBF obtained
using DSC-MRI and Xe-133 SPECT, using both a linear relationship and a non-linear relationship when applying a venous output function (VOF) correction
scheme to DSC-MRI data from healthy subjects. The results showed that the observed degrees of correlation were similar when the linear and non-linear
relationships were applied to the AIF and VOF from DSC-MRI.
DSC Perfusion: AIF Detection
Hall B Thursday 13:30-15:30
1787. Robust Arterial Input and Venous Output Function Detection for Automatic Processing in DSC-MRI
Matus Straka 1 , Gregory W. Albers 2 , Roland Bammer 1
1 Radiology, Stanford University, Stanford, CA, United States; 2 Stroke Center, Stanford University Medical Center, Stanford, CA,
United States
Routine acquisition of DSC-MRI PWI datasets highly benefits from full automated post-processing. Selection of arterial input and venous output function is
a key step that ensures robustness and reliability of unsupervised processing. A novel method of AIF and VOF selection is proposed by means of tubular
filtering and simple analysis of mean temporal signals. Weighting factors the favor arterial and venous signals, as well as vessel orientations are derived. As
a result, robustness of AIF and VOF selection was improved.