[Tissue contrast in MRI owing to intermolecular multiple-quantum coherences (iMQC)].
Dipole-dipole interactions in 1H NMR of liquids permit a new tissue contrast in MR imaging (MRI). For this purpose, the CRAZED (COSY Revamped by Asymmetric Z-gradient Echo Detection) sequence which simply consists of two radiofrequency pulses of delay tau and a magnetic field gradient pulse of strength G, is applied to create intermolecular multiple-quantum coherences of dipolar-coupled ensembles of water protons with spatial distance d = pi/(gammaGtau). As a consequence, the measured signal originates from "sources" that have a tunable dimension. CRAZED was first applied to MR imaging at 1.5 T by Zhong et al. To study the contrast properties and influence of sequence parameters of this technique, we implemented different sequences of this type on a clinical 1.5-T whole-body tomograph. The sequences were optimized in experiments with agar gel phantoms. We obtained images with dipolar contrast from the brain of healthy volunteers. The gradient system enabled correlation distances d in the range of 0.05 mm to 1 mm.
Kirsch
Stefan
S
Medizinische Physik in der Radiologie, Deutsches Krebsforschungszentrum, Heidelberg, FRG.
Bachert
Peter
P
D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging / Q000379:methods*; D011522:Protons; D011789:Quantum Theory; D012680:Sensitivity and Specificity; D014867:Water
D011522:Protons; D014867:Water