胰岛素瘤的MRI诊断

目的：探讨胰岛素瘤的MRI表现及最佳检查序列。资料与方法：分析经手术、病理证实6例胰岛素瘤的MRI表现,检查序列包括SE T1WI、FSE T2WI、预饱和脂肪抑制T1WI,常规增强和动态增强检查。其中4例行CT平扫和双期增强检查。比较增强前后MRI不同序列胰岛素瘤的检出率,并与CT检查进行对照。结果：MRI检出了所有6例胰岛素瘤,其中预饱和脂肪抑制T1WI的检出率最高（6／6）,其次是常规SE T1WI（5／6）,而FSE T2WI（2／6）、常规增强T1WI（2／5）和动态增强检查（2／3）的显示率较低,但增强检查尤其是动态增强检查有助于显示肿瘤的富血供特征。CT对胰岛素瘤的检出率（平扫1／4,双期增强2／3）要低于MRI。结论：对于胰岛素瘤,MRI是一种较佳无创性检查方法,能够检出双期增强CT检查漏诊的肿瘤。MR预饱和脂肪抑制T1WI是最佳检查序列,增强尤其是动态增强则能反映肿瘤的富血供特征。

MRI Diagnosis of Insulinomas

Objective To discuss MRI features of insulinomas and to explore the optimal MRI scanning sequence.Materials and Methods MRI findings in 6 patients with surgically and pathologically proved insulinomas were analyzed. The scanning sequences used in this study included SE T 1WI, FSE T 2WI, presaturation fat suppressed T 1WI, and both conventional and dynamic contrast enhanced scanning. Additional plain and dual phase contrast enhanced CT scanning was done in 4 cases. The detecting rates of the tumor on the pre and post contrast MRI of different sequences were analyzed, and the results were compared with that of CT scans.Results All the 6 insulinomas were demonstrated on MRI. For presaturation fat suppressed T 1WI the detecting rate was the highest (6/6), for the other sequences the detecting rate was SE T 1WI (5/6), FSE T 2WI (2/6), conventional enhanced T 1WI (2/5) and dynamic enhanced T 1WI (2/3). Contrast enhanced, especially dynamic, scanning well displayed the features of hypervascularity of the tumor. The sensitivity of CT was lower than that of MRI.Conclusion MRI is an optimal, noninvasive technique for the detection of insulinoma, it can even reveal the lesions failed to be demonstrated on dual phase enhanced CT scans. Presaturation fat suppressed T 1WI is the best scanning sequence, while the dynamic enhanced scan can show the hypervascularity of the tumor.