Modeling the residue function in DSC-MRI simulations: analytical approximation to in vivo data.
OBJECTIVE
An exponential residue function is commonly used in numerical simulations to assess the accuracy of perfusion quantification using dynamic susceptibility contrast (DSC) MRI. Although this might be a reasonable assumption for normal tissue, microvascular hemodynamics are likely to be significantly altered in pathology. Thus the exponential function may no longer be appropriate and the estimated accuracy of DSC-MRI quantification might be inappropriate. The purpose of this study was to characterize in vivo residue function variations in normal and infarcted tissue in a chronic atherosclerotic disease cohort, and to find the most appropriate model for use in DSC simulations.


METHODS
Residue functions were measured in vivo in patients with atherosclerotic disease using a nonparametric Control Point Interpolation method, which has been shown to provide a robust characterization of the shape of the residue function. The observed residue functions were approximated with five commonly used analytical expressions: exponential, bi-exponential, Lorentzian, and Fermi functions, and a previously proposed Vascular Model.


RESULTS
The lowest error was found with the bi-exponential function approximations to the in vivo residue functions from both normal and infarcted tissue.


CONCLUSIONS
A bi-exponential model should therefore be used in future numerical simulations of DSC-MRI instead of the exponential function.
Institute of Biomedical Engineering, University of Oxford, United Kingdom.
Amit
A
Mehndiratta
Fernando
F
Calamante
Bradley J
BJ
MacIntosh
David E
DE
Crane
Stephen J
SJ
Payne
Michael A
MA
Chappell
D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D003198:Computer Simulation; D003287:Contrast Media; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D017352:Echo-Planar Imaging; D005260:Female; D019786:Gadolinium DTPA; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D002537:Intracranial Arteriosclerosis / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D059629:Signal-To-Noise Ratio
D003287:Contrast Media; D019786:Gadolinium DTPA
DSC simulation; deconvolution; perfusion digital phantom; residue function