Image-derived mean velocity measurement for prediction of coronary flow reserve in a canonical stenosis phantom using magnetic particle imaging

Abstract

Introduction Aim of this study is to evaluate whether magnetic particle imaging (MPI) is capable of measuring velocities occurring in the coronary arteries and to compute coronary flow reserve (CFR) in a canonical phantom as a preliminary study. Methods For basic velocity measurements, a circulation phantom was designed containing replaceable glass tubes with three varying inner diameters, matching coronary-vessel diameters. Standardised boluses of superparamagnetic-iron-oxide-nanoparticles were injected and visualised by MPI. Two image-based techniques were competitively applied to calibrate the respective glass tube and to compute the mean velocity: full-duration-at-half-maximum (FDHM) and tracer dilution (TD) method. For CFR-calculation, four necessary settings of the circulation model of a virtual vessel with an inner diameter of 4 mm were generated using differently sized glass tubes and a stenosis model. The respective velocities in stenotic glass tubes were computed without recalibration. Results On velocity level, comparison showed a good agreement (rFDHM = 0.869, rTD = 0.796) between techniques, preferably better for 4 mm and 6 mm inner diameter glass tubes. On CFR level MPI-derived CFR-prediction performed considerably inferior with a relative error of 20–44%. Conclusions MPI has the ability to reliably measure coronary blood velocities at rest as well as under hyperaemia and therefore may be suitable for CFR calculation. Calibration-associated accuracy of CFR-measurements has to be improved substantially in further studies.

Magnetic Particle Imaging: From Tracer Design to Biomedical Applications in Vasculature Abnormality

“…The MPI modality was also used to evaluate changes in blood flow velocity. Except for model testing to predict the mean velocity of coronary flow reserve, [ 228 ] a new system adapting Doppler ultrasound and perimag ‐MPI was reported to estimate the flow velocity over a more extensive range. Its detection relying on quantifying the speed of particle distributions (linearly from 0 to 1.5 m s −1 and even 2.0 m s −1 theoretically) and enabled more robust velocity measurement within milliseconds and higher accuracy than the detection method purely based on MPI.…”

Saline bolus for negative contrast perfusion imaging in magnetic particle imaging

“…Graeser et al 2019;Matthias Graeser, Ludewig, et al 2020;Michael Gerhard Kaul et al 2021;Ludewig, Matthias Graeser, et al 2022;Østergaard et al 1996;Østergaard 2005;Cha 2003;Wintermark et al 2005). Other work focused on blood flow velocity (Michael G. Kaul et al 2018), kidney perfusion (Molwitz et al 2019) or blood flow with stenosis (Siepmann et al 2021), using similar methods. Apart from an increase in concentration, perfusion parameters may also be obtained from a concentration decrease, known from Magnetic Resonance Imaging (MRI) as negative contrast (Detre et al 1992;Barbier, Lamalle, and Décorps 2001).…”