同相位与反相位梯度回波T_1WI在肝脏的应用价值

目的　评估同相位与反相位梯度回波T1WI在肝脏应用的价值 ,尤其是评估其对肝内脂肪变的检测能力。方法　 76例病人采用屏气同相位与反相位T1W梯度回波序列对肝脏扫描。将76例病人分成 3组分析 :(1)肝内无占位病变组 ,8例 ;(2 )肝癌组 ,34例 ;(3)血管瘤或囊肿组 ,共 34例。对 2种序列的图像进行了定量分析。结果　 76例中发现 14例肝脂肪变 ,6 2例无脂肪变。在 14例肝脂肪变中 ,反相位MRI还显示了 4例低信号肿块周边环状高信号带 ,其中 3例肝癌 ,1例血管瘤。在肝脂肪变的反相位上显示肝与脾和病灶信噪比或对比信噪比值较同相位低 ,但肝与脾和病灶间信噪比 (SNR)或对比信噪比 (CNR)在同相位与反相位上均无显著性差异 (P >0 .0 5 )。结论　同相位与反相位对显示肝脏病变和对脂肪成分的诊断是有价值的。两者互补 ,缺一不可。为避免肝脏病变在T1WI上的误诊或漏诊 ,建议常规行同相位与反相位T1W扫描

Evaluation on the value of in phase and opposed phase T_1 weighted breath hold FLASH sequences for hepatic imaging

Objective To evaluate the value of the combined in phase (IP) and opposed phase (OP) T 1 weighted breath hold FLASH sequences for hepatic imaging, particularly for fat content. Methods Non contrast enhanced IP and OP T 1 W GRE breath hold images were obtained in 76 patients refereed for liver MRI study at 1 5 T. Seventy six patients were analyzed in three groups : (1) no liver mass ( n =8); (2) liver with hepatoma ( n =34); (3) liver with haemangioma or cyst ( n =34). Liver/spleen and liver/lesion signal to noise (SNR) and contrast to noise ratio (CNR) were assessed for lesion detectability. Images between IP and OP sequences were compared quantitatively. Results There was no statistically significant difference when comparing IP and OP sequences for liver/spleen and liver/lesion SNR. In patients with fatty infiltration, the OP sequences yielded substantially lower values for liver/spleen and liver/lesion SNR than the IP sequences. Furthermore, OP imaging detected fatty infiltration in 14 cases and demonstrated hyperintense peritumorous rim in 4 cases. Also, in several cases with fatty infiltration, many more lesions were identified using IP images. Conclusion The use of IP and OP GRE sequences provides complementary diagnostic information. Focal liver lesions may be obscured in the presence of fatty infiltration if only OP sequences are employed. A complete assessment of the liver with MR should include both IP and OP imaging.