Traditional Posters: Diffusion & Perfusion - ismrm

DSC Perfusion: Processing Methods
Hall B Monday 14:00-16:00
1791. Acuracy and Reliability of Post-Processing Software for DSC MR Perfusion:
Quantitative Analysis by Digital Phantom Data
Kohsuke Kudo 1 , Soren Christensen 2 , Makoto Sasaki 1 , Matus Straka 3 , Shunrou Fujiwara 1 ,
Kinya Ishizaka 4 , Yuri Zaitsu 4 , Noriyuki Fujima 4 , Satoshi Terae 4 , Kuniaki Ogasawara 5 ,
Leif Ostergaard 6
1 Advanced Medical Research Center, Iwate Medical University, Morioka, Iwate, Japan; 2 Departments of
Neurology and Radiology, University of Melbourne, Melbourne, Australia; 3 Department of Radiology, Stanford
University, CA, United States; 4 Department of Radiology, Hokkaido University Hospital, Sapporo, Japan;
5 Department of Neurosurgery, Iwate Medical University, Morioka, Iwate, Japan; 6 Department of
Neuroradiology, Aarhus University Hospital, Aarhus, Denmark
A variety of post-processing programs and algorithms for dynamic susceptibility contrast (DSC) MR perfusion are available; however,
the accuracy and reliability of these programs have not been subject to a standardized quality control. We developed digital phantom
data set, to evaluate the accuracy and characteristics of quantitative values derived from DSC perfusion analysis software. By using
this phantom, we could check tracer-delay dependency for CBF, CBV, MTT, and Tmax, as well as linearity of CBF and MTT against
true values.
1792. Spin Echo Amplitude in Biological Tissue with Implications for Vessel Size Imaging
Valerij G. Kiselev 1
1 Medical Physics, Dpt. of Diagnostic Radiology, University Hospital Freiburg, Freiburg, BW, Germany
Transverse relaxation in living tissue is contributed by the dephasing of spins due to diffusion in mesoscopic magnetic fields induced,
for example, by paramagnetic tracer in the blood pool. The associated correlation time is commensurate with the echo time of typical
measurement sequences. Varying the echo time changes the character of dephasing from reversible for short TE to irreversible for
long TE. This dependence is quantified by calculating the transverse relaxation rate in the capillary network for multiple refocusing
pulses in the static dephasing regime. This yields a modified formula for the mean vessel size in the vessel size imaging.
1793. Equivalence of CBV Measurement Methods 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
Two widely used methods exist for computing cerebral blood volume (CBV) in DSC-MRI perfusion, using measured signals as well
as deconvolved residue function. Some authors claim that these methods do not deliver identical results. We explain that the methods
must deliver equivalent results and any difference in obtained values is just caused by signal post-processing errors and wrong
interpretation of indicator-dilution theory and convolution theorem. Identity of the two methods is shown in time- and frequencydomains
as well as by means of numerical results. Possible sources of the processing errors are discussed and solutions how to avoid
those are proposed.
1794. Design of a Data Driven Deconvolution Filter for DSC Perfusion
Philipp Emerich 1 , Peter Gall 1 , Birgitte Fuglsang Kjølby 2 , Elias Kellner 1 , Irina Mader 3 ,
Valerij Kiselev 1
1 Medical Physics, University Hospital Freiburg, Freiburg, Germany; 2 Dept. of Neuroradiology, Arhus
University Hospital, Arhus, Denmark; 3 Dept. of Neuroradiology, University Hospital Freiburg, Freiburg,
Germany
Bolus tracking perfusion evaluation relies on the deconvolution of a tracer concentration time-courses in an arterial and a tissue voxel
following the tracer kinetic model. The object of this work is to propose a method to design a data driven Tikhonov regularization
filter in the Fourier domain and to compare it to the singular value decomposition (SVD) based approaches using the mathematical
equivalence of Fourier and circular SVD (oSVD).
1795. On the Form of the Residue Function for Brain Tissue
Peter Gall 1 , Valerij Kiselev 1
1 Medical Physics, University Hospital Freiburg, Freiburg, Germany
The residue function, R(t), is fundamental for description of microcirculation. To define this function is one of the aims of DSC
perfusion MRI. It is found by solving an ill-posed problem, the deconvolution, for which one of approaches is to fit a model R(t) to
data. Commonly, phenomenological functional shapes are used to model R(t) respecting only its most general properties. Studies
based on ASL indicate insufficiency of this approach. In this work we present a derivation the residue function from the laws of
laminar flow and a model for the architecture of the vascular tree.