Effects of contrast material on single-volume proton MR spectroscopy.

BACKGROUND AND PURPOSE Administration of contrast material before proton MR spectroscopy may allow more accurate placement of the volume of interest, particularly in tumors; yet, some data have suggested that contrast material may alter the results of MR spectroscopy. To determine the validity of this contention, we performed pre- and postcontrast MR spectroscopy in patients with brain tumors and compared the results with those obtained from a phantom. METHODS Ten patients with astrocytomas were examined with single-volume MR spectroscopy before and after administration of contrast material. Voxel placement was identical for all studies. Peak area, peak height, and width at half maximum were measured for N-acetyl aspartate (NAA), creatine (Cr), and choline (Cho) in all studies. A phantom containing a 10 mmol concentration of NAA, Cr, and Cho was prepared in phosphate-buffered saline and mixed with contrast concentrations varying from 0.1 to 1.0 mmol. The phantom was studied by MR spectroscopy with the same parameters as used for the clinical studies. RESULTS No significant differences were found between the pre- and postcontrast MR spectroscopy studies for the three parameters measured. In phantom studies, there was a significant decline in the Cho peak area and height and an increase in the width at half maximum as the concentration of contrast material increased from 0.1 to 1.0 mmol. NAA and Cr peaks showed no significant changes in peak height or area. CONCLUSION Contrast material may be administered before clinical MR spectroscopy without affecting its interpretation.