Bitte wählen Sie ihr Lieferland und ihre Kundengruppe
Objective was artifact examination of Ti(49.8)Ni(50.2) medical grade wire in MRI. 3 mm diameter Nitinol wire was annealed at 1000 degC for 30 minutes, centerless ground and electro-polished (EP). Sections were oxidized in air at 400-1.000 degC in 100 degC increments for up to 100 minutes. Magnetic attraction of samples was determined. MR examination performed in a 0.3 T Hitachi and 1.0 T/1.5 T Philips. Samples were placed in a water filled test container, parallel and perpendicular to main field. Spin (TR/TE=300/30 ms) and gradient (TR/TE=100/6 ms, FA=40 %) echo was obtained using a head coil. Oxide thickness was proportional to oxidation temperature. Magnetic force on sample 1000 degC 0.48 mN; for sample 800 deg C 0.05 mN, no attraction with others. Artifact size was proportional to field strength and oxide thickness. GE was more sensitive than SE. From low-field (0.3 T) to high- field MRI (1.5 T) artifact size changed from 25x to 47x the original size for 1000 degC. No differentiation between samples up to 700 degC.