In vivo proton magnetic resonance spectroscopy of large focal hepatic lesions and metabolite change of hepatocellular carcinoma before and after transcatheter arterial chemoembolization using 3.0-T MR scanner

PURPOSE: To investigate the value of in vivo proton magnetic resonance spectroscopy (MRS) in the assessment of large focal hepatic lesions and to measure the metabolite change of hepatocellular carcinoma (HCC) after transcatheter arterial chemoembolization (TACE) using 3.0-T scanner. MATERIALS AND METHODS: In this prospective study, 43 consecutive patients with large (not less than 3 cm in diameter) hepatic tumors and eight normal volunteer were included. MRS of the lesions in addition to uninvolved liver parenchyma was carried out using a whole-body 3.0-T scanner. Among the patients with proven HCC, eight lesions were evaluated before and two to five days after TACE. The choline-to-lipid (cho/lipid) ratio was measured by dividing the peak area of choline at 3.2 ppm by the peak area of lipid at 1.3 ppm. The sensitivity and specificity profiles of MRS in the diagnosis of malignant hepatic tumors were determined by plotting empirical receiver operating characteristic (ROC) curve. The mean cho/lipid ratios in different groups before and after TACE were also measured. RESULTS: The technical success rate for MRS was 90% (53/59). The ROC curve showed proton MRS has moderate discriminating ability in diagnosing malignant hepatic tumors, although the sensitivity was less than 50% while 1-specificity was less than 20%. The area under the curve was 0.71 (P < 0.05). The mean +/- 1 standard error (SE) of cho/lipid ratios for uninvolved liver (N = 8), benign tumor (N = 8), and malignant tumor (N = 21; 19 HCC, one angiosarcoma, and one lymphoma) were 0.06 +/- 0.02, 0.02 +/- 0.02, and 0.17 +/- 0.05, respectively. A significantly statistical difference (ANOVA planned contrast test, P = 0.01 and Games-Howell procedure, P = 0.03) was achieved in the mean cho/lipid ratio between malignant and benign tumors. The mean cho/lipid ratios were significantly decreased from 0.23 +/- 0.11 before TACE to 0.01 +/- 0.00 after the treatment (t = 2.01, P < 0.05, one-tail paired t-test; z = -2.37, P < 0.05, Wilcoxon Signed Ranks Test). CONCLUSION: In vivo proton MRS is technically feasible for the evaluation of focal hepatic lesions. The technique has potential in the detection of early metabolite change in malignant liver tumors after TACE but limitation still exists in clear differentiation between normal liver and benign and malignant tumor.