Effect of T1 shortening on T2-weighted MRI sequences: comparison of hepatic mass conspicuity on images acquired before and after gadolinium enhancement.

摘要

OBJECTIVE: The purpose of this study was to compare the conspicuity of hepatic lesions on T2-weighted fast-recovery fast spin-echo MR images obtained before and after administration of gadolinium. MATERIALS AND METHODS: We reviewed T2-weighted fast-recovery fast spin-echo images before and after gadolinium enhancement for 84 patients with 118 focal liver lesions. Solid lesions (22 hepatomas, seven ablated hepatomas, 12 metastatic lesions, six cases of focal nodular hyperplasia, five dysplastic nodules, one adenoma) were proved pathologically or with multiple follow-up studies. Nonsolid lesions were diagnosed as hemangiomas (n = 33) or cysts (n = 32) on the basis of imaging features. Two blinded radiologists interpreted the images independently, reading unenhanced images first and gadolinium-enhanced images at least 2 weeks later. Lesion conspicuity was ranked as follows: 1, poor; 2, moderate; 3, good; 4, excellent. The sign test was used for qualitative scoring of imaging pairs (unenhanced and gadolinium enhanced). The Fisher's exact test was used for subgroup analysis of solid and nonsolid lesions. RESULTS: On gadolinium-enhanced T2-weighted images, 21 (17.8%) of 118 of the lesions had improved conspicuity, 86 (72.9%) had no difference in conspicuity, and 11 (9.3%) appeared worse. No statistically significant difference was found between unenhanced and enhanced images (p = 0.11), but a trend toward improved conspicuity with gadolinium enhancement was observed. Subgroup analysis showed that on gadolinium-enhanced T2-weighted images, visualization of solid hepatic lesions (28.3%) was significantly better than that of nonsolid lesions (9.2%) (p = 0.01). CONCLUSION: Compared with unenhanced T2-weighted images, gadolinium-enhanced T2-weighted images had a trend toward improved conspicuity of focal liver lesions. Subgroup analysis showed that visualization of solid lesions benefited significantly more from use of gadolinium-enhanced T2-weighted sequences than did visualization of nonsolid lesions.