Towards measuring the effect of flow in blood T-1 assessed in a flow phantom and in vivo

Journal Article (2020)
Author(s)

I. Hermann (University Heidelberg, Universitatsmedizin Mannheim, TU Delft - ImPhys/Computational Imaging)

Tanja Uhrig (University Heidelberg, Universitatsmedizin Mannheim)

Jorge Chacon-Caldera (University Heidelberg, Universitatsmedizin Mannheim)

Mehmet Akçakaya (University of Minnesota)

Lothar R. Schad (University Heidelberg, Universitatsmedizin Mannheim)

S.D. Weingärtner (TU Delft - ImPhys/Medical Imaging, TU Delft - ImPhys/Computational Imaging)

Research Group
ImPhys/Computational Imaging
Copyright
© 2020 I. Hermann, Tanja Uhrig, Jorge Chacon-Caldera, Mehmet Akcakaya, Lothar R. Schad, S.D. Weingärtner
DOI related publication
https://doi.org/10.1088/1361-6560/ab7ef1
More Info
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Publication Year
2020
Language
English
Copyright
© 2020 I. Hermann, Tanja Uhrig, Jorge Chacon-Caldera, Mehmet Akcakaya, Lothar R. Schad, S.D. Weingärtner
Research Group
ImPhys/Computational Imaging
Issue number
9
Volume number
65
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Abstract

Measurement of the bloodT1time using conventional myocardialT1mapping methods hasgained clinical significance in the context of extracellular volume (ECV) mapping and synthetichematocrit (Hct). However, its accuracy is potentially compromised by in-flow ofnon-inverted/non-saturated spins and in-flow of spins which are not partially saturated fromprevious imaging pulses.Bloch simulations were used to analyze various flow effects separately.T1measurements ofgadolinium doped water were performed using a flow phantom with adjustable flow velocities at3 T. Additionally,in vivobloodT1measurements were performed in 6 healthy subjects (26±5years, 2 female). To study theT1time as a function of the instantaneous flow velocity,T1timeswere evaluated in an axial imaging slice of the descending aorta. Velocity encoded cinemeasurements were performed to quantify the flow velocity throughout the cardiac cycle.Simulation results show more than 30% loss in accuracy for 10% non-prepared in-flowingspins. However, in- and out-flow to the imaging plane only demonstrated minor impact on theT1time. PhantomT1times were decreased by up to 200 ms in the flow phantom, due to in-flow ofnon-preparedspins.Highflowvelocitiescausein-flowofspinsthatlackpartialsaturationfromtheimaging pulses but only lead to negligibleT1time deviation (less than 30 ms).In vivomeasurements confirm a substantial variation of theT1time depending on the flow velocity. Thehighest aorticT1times are observed at the time point of minimal flow with increased flow velocityleading to reduction of the measuredT1time by up to130±49 ms at peak velocity.In this work we attempt to dissect the effects of flow onT1times, by using simulations,well-controlled, simplified phantom setup and the linear flow pattern in the descending aortain vivo.