Enhancement efficacy of magnetic starch microshperes (MSM) in conventional spin-echo and turbo spin-echo sequences at 0.5 T and 1.5 T.
The efficacy of the superparamagnetic contrast agent magnetic starch microspheres (MSM) was evaluated in vitro by NMR relaxometry and in vivo by MR imaging using T2-weighted spin-echo (SE) and turbo spin-echo (TSE) sequences at 0.5 T and 1.5 T in 60 normal rats who received MSM in doses of 10-50 mu mol/kg. MR imaging was performed using T2-weighted SE and TSE sequences. The relaxation rates 1/T1 and 1/T2 for liver and spleen increased linearly with MSM concentrations up to 30 mu mol/kg body weight, and approached almost constant levels for higher doses. The slopes in the linear part of the 1/T2 diagram were 0.62 Hz +/- 0.03 for the liver and 0.51 Hz +/- 0.06 x kg/mu mol for the spleen. On all T2-weighted sequences at 0.5 T and 1.5 T, liver signal-to-noise ratio (SNR) decreased by a factor of 2-3 already at the lowest dose of 10 mu mol/kg. SNR values of TSE sequences exceeded values for SE sequences by 50-80%. The SNR decrease was not significantly different between SE and TSE sequences. Our results show that MSM is well suited as a T2 contrast agent at both magnetic field strengths when using conventional SE and fast TSE sequences.
Kreft
B
B
Department of Radiology, University of Bonn, Germany.
Block
W
W
Muhlhauser
J
J
Traber
F
F
Oksendal
A
A
Schild
H
H
D000818:Animals; D003287:Contrast Media; D005260:Female; D005290:Ferric Compounds; D008099:Liver / Q000033:anatomy & histology; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008863:Microspheres; D010316:Particle Size; D051381:Rats; D017207:Rats, Sprague-Dawley; D013154:Spleen / Q000033:anatomy & histology; D013213:Starch
D003287:Contrast Media; D005290:Ferric Compounds; C000499:ferric oxide; D013213:Starch