Short-echo time proton MR spectroscopy in the presence of gadolinium

Purpose: The purpose of this work was to quantify the impact of contrast agents on short-TE single-voxel H-1 MR spectroscopy (MRS) diagnosis of recurrent brain tumors. Method: Short-TE H-1 MRS was pet-formed in 49 patients with biopsy-proven brain tumors and 14 control subjects. Eight patients (nine paired exams) were examined before and after administration of Gd-DTPA (interval approximately 5-7 min). Results: Tumor spectra showed increased choline/creatine ratio (Cho/Cr; p < 0.009) and Cho concentrations (p < 0.02). Receiver operator characteristic for Cho/Cr = 0.93 differentiated 100% of tumors from control in the absence or presence of contrast agent. Repeated H-1 MRS varied <3%. Cho T2 was significantly longer than Cr T2 (p < 0.02). Conclusion: Proton MRS with TE of 30 ms may safely be used in combined contrast-enhanced MRI/MRS protocols. Further study is required with long-TE MRS because of the prolonged T2 of Cho.