Functional molecular imaging of tumors by chemical exchange saturation transfer MRI of 3-O-Methyl-D-glucose.

To evaluate the feasibility to detect tumors and metastases by the chemical exchange saturation transfer (CEST) MRI technique using 3-O-Methyl-D-glucose (3OMG), a nonmetabolizable derivative of glucose that is taken up rapidly and preferentially by tumors and is entirely excreted by the kidneys. In vivo CEST MRI experiments were performed on a Bruker 7 Tesla Biospec on implanted orthotopic mammary tumors of mice before and following i.p. injection of 3OMG. The CEST images were generated by a series of gradient-echo images collected from a single 1 mm coronal slice after a 1.2 s presaturation pulse, applied at offsets of ±1.2 ppm from the water and at B(1) power of 2.5 µT. Following 3OMG (1.5 g/kg) i.p. injection, an enhanced CEST effect of approximately 20% was visualized at the tumor within a few minutes. The signal slowly declined reaching half of its maximum at approximately 80 min. Due to the large CEST effect of 3OMG and its low toxicity 3OMG-CEST may serve for the detection of tumors and metastases in the clinic.