RESUMO
The quantification of choline-containing compounds (Cho) in hepatic tumors by (1)H MR spectroscopy (MRS) is of great interest because such compounds have been linked to malignancy. In this study, a practical external phantom replacement method for the absolute quantification of hepatic metabolites is demonstrated. We performed experiments at 3 T using a body coil, and used an external phantom containing choline chloride for calibration. We first tested the quantification strategy to confirm its suitability in vivo using a phantom of known concentration and normal brain tissue. The results obtained after coil loading and T(1) and T(2) effects were corrected for were consistent with the known concentration and previously published values. To demonstrate its feasibility, we applied the technique to liver studies conducted on five normal volunteers and four patients with hepatocellular carcinoma, and one patient (also in the latter group) who had undergone post-transcatheter arterial chemoembolization (TACE). The Cho concentrations in the four patients were estimated to be 3.4, 6.3, 7.4, and 14.0 mM, respectively. These values are substantially higher than those obtained from the healthy volunteers (1.3 +/- 0.9 mM (mean +/- SD)). The results indicate that the proposed method is accurate and requires fewer tedious procedures for MRS; therefore, it may be a promising technique for evaluating response to treatment in liver cancer.
