３．０Ｔ ＭＲ装置による肝臓のＴ２＊ｍａｐ測定シーケンスの検討

Abstract

T2* value measurement of the liver parenchyma with a 3.0T MR scanner may be useful for evaluating focal liver function. Currently, there are 2 sequences for measurement of T2* value of the liver: multi-echo fast field echo (mFFE), and multi-echo planar imaging (EPI). We can correct inhomogeneity of the local magnetic field with the EPI sequence; however, the spatial resolution is poor. On the other hand, mFFE has a relatively high spatial resolution but cannot correct inhomogeneity of the local magnetic field. We investigated the two measurement methods of a T2* map that measured the T2* images obtained with mFFE and EPI sequences by using a 3.0T MR scanner in the phantom and patient studies. In the phantom studies, T2* values measured on images with the mFFE sequence were affected by inhomogeneity of the local magnetic field, but T2* values measured on images with the EPI sequence were showed no difference by corrected inhomogeneity of local magnetic field. However, in the clinical study, we found good agreement in T2* values of the liver measured on images with mFFE and EPI sequences. Therefore, the mFFE sequence can be an alternative to the EPI sequence in the clinical setting. It is occasionally difficult to identify normal or pathological structures on images obtained with the EPI sequence because of its low spatial resolution. The spatial resolution of images obtained with the mFFE sequence is much better than that with the EPI sequence. Based on these discussions, we believe that the mFFE sequence may be appropriate for the measurement of T2* values in the liver in the clinical setting.