Rapid measurement of Gd-DTPA extraction fraction in a dialysis system using echo-planar imaging

• Published in: Medical physics (Lancaster) 1997-12, Vol.24 (12), p.1907-1913
• Main Authors: Niendorf, Eric R., Grist, Thomas M., Frayne, Richard, Brazy, Peter C., Santyr, Giles E.
• Format: Article
• Language: English
• Subjects: 87.58.06; 87.58.10; artificial organs; biomedical measurement; biomedical NMR; Data acquisition; Dialysis; Echo-Planar Imaging - methods; Filtration; Flow visualization; gadolinium; Gadolinium DTPA - pharmacokinetics; Humans; kidney; Kidney - anatomy & histology; Kidney - physiology; Magnetic resonance imaging; Medical imaging; Models, Theoretical; Physicists
• ISSN: 0094-2405; 2473-4209
• DOI: 10.1118/1.598104

Gd-DTPA (Magnevist, Berlex, Wayne, NJ) extraction fractions (EF) have been measured for three dialysis filter types using an echo-planar imaging (EPI) Look-Locker T 1 measurement technique under conditions of fast and slow flow. The mean EF measured in Fresenius (Bad Homburg, Germany) F3, F6, and F8 dialysis filters were 0.015±0.005, 0.053±0.004, and 0.084±0.003, respectively, under conditions of fast flow which provided complete refreshment of spins in the intervals between read-out pulse samples of the T 1 relaxation recovery. Data acquisition and post-processing techniques were developed to extend the accuracy of the LL technique to systems with slow flow which did not provide complete refreshment of spins between samples of the T 1 recovery. A multi-shot EPI LL interleaved acquisition of relaxation recovery space (IRRS) provided T 1 measurement accuracy comparable to the refreshed system, ± 10, but at the expense of increased scan times (factor of 2 or 3). Discarding the first few non-equilibrium relaxation recovery samples from the T 1 fit allowed accurate T 1 estimation (± 10) with a single-shot EPI LL method under conditions of slow flow. These EPI LL EF measurement methods may provide useful techniques for evaluating renal function in vivo.