Dependency of R 2 and R 2 relaxation on Gd-DTPA concentration in arterial blood: Influence of hematocrit and magnetic field strength

Dynamic susceptibility contrast (DSC) MRI is clinically used to measure brain perfusion by monitoring the dynamic passage of a bolus of contrast agent through the brain. For quantitative analysis of the DSC images, the arterial input function is required. It is known that the original assumption of...

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Bibliographic Details
Published in:NMR in biomedicine 2022-05, Vol.35 (5), p.e4653
Main Authors: van Dorth, Daniëlle, Venugopal, Krishnapriya, Poot, Dirk H J, Hirschler, Lydiane, de Bresser, Jeroen, Smits, Marion, Hernandez-Tamames, Juan A, Debacker, Clément S, van Osch, Matthias J P
Format: Article
Language:English
Subjects:
Contrast Media
Gadolinium DTPA
Hematocrit
Humans
Magnetic Fields
Magnetic Resonance Imaging - methods
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Summary:Dynamic susceptibility contrast (DSC) MRI is clinically used to measure brain perfusion by monitoring the dynamic passage of a bolus of contrast agent through the brain. For quantitative analysis of the DSC images, the arterial input function is required. It is known that the original assumption of a linear relation between the R relaxation and the arterial contrast agent concentration is invalid, although the exact relation is as of yet unknown. Studying this relation in vitro is time-consuming, because of the widespread variations in field strengths, MRI sequences, contrast agents, and physiological conditions. This study aims to simulate the R versus contrast concentration relation under varying physiological and technical conditions using an adapted version of an open-source simulation tool. The approach was validated with previously acquired data in human whole blood at 1.5 T by means of a gradient-echo sequence (proof-of-concept). Subsequently, the impact of hematocrit, field strength, and oxygen saturation on this relation was studied for both gradient-echo and spin-echo sequences. The results show that for both gradient-echo and spin-echo sequences, the relaxivity increases with hematocrit and field strength, while the hematocrit dependency was nonlinear for both types of MRI sequences. By contrast, oxygen saturation has only a minor effect. In conclusion, the simulation setup has proven to be an efficient method to rapidly calibrate and estimate the relation between R and gadolinium concentration in whole blood. This knowledge will be useful in future clinical work to more accurately retrieve quantitative information on brain perfusion.
ISSN:0952-3480
1099-1492
DOI:10.1002/nbm.4653