MR-IMAGING CONTRAST ENHANCEMENT BASED ON INTERMOLECULAR ZERO-QUANTUM COHERENCES

A new method for magnetic resonance imaging (MRI) based on the detecti on of relatively strong signal from intermolecular zero-quantum cohere nces (iZQCs) is reported. Such a signal would not be observable in the conventional framework of magnetic resonance; it originates in Long-r ange dipolar couplings (10 micrometers to 1 millimeter) that are tradi tionally ignored. Unlike conventional MRI, where image contrast is bas ed on variations in spin density and relaxation times (often with inje cted contrast agents), contrast with iZQC images comes from variations in the susceptibility over a distance dictated by gradient strength. phantom and in vivo (rat brain) data confirm that iZQC images give con trast enhancement. This contrast might be useful in the detection of s mall tumors, in that susceptibility correlates with oxygen concentrati on and in functional MRI.