胰腺MRI:2D与3D FS-FLASH增强扫描序列的对比研究

目的:通过2D与3D增强扫描序列的对比研究,确定胰腺MRI最佳增强扫描序列。方法:40例胰外疾病患者随机分为2D组和3D组(每组各20例)。常规MRI平扫后行胰腺多时相动态增强扫描。测量平扫T1WI像及增强各期胰腺的信号强度,计算信噪比(SNR)及对比信噪比(CNR),并对图像质量进行评价。结果:平扫T1WI像:3D组胰腺SNR、胰腺-胰周脂肪CNR均明显低于2D组(19.2 vs 22.7,8.7 vs 15.2,P<0.05)。增强后扫描:3D组各期图像的胰腺SNR均高于同期扫描的2D组(37.8 vs 29.4;31.6 vs 28.8;29.6 vs 28.0),尤以胰腺实质期为明显(P<0.05),同时胰腺-胰周脂肪CNR及图像质量亦高于2D组(P<0.05)。结论:3D FLASH序列是胰腺MRI最优增强扫描序列,能更好地显示胰腺的解剖细节和血液动力学特征,有助于胰腺疾病的诊断及可切除性评价。

MR imaging of the pancreas: comparison between two-dimensional and three-dimensional gradient-echo sequence

Objective: Comparison of two-dimensional with three-dimensional sequence MRI, to determine the optimum dynamic enhancement sequence for the pancreas. Materials and Methods: Forty patients without any pancreatic disease were randomly assigned to 2D, 3D groups according to scanning sequences(2D and 3D FLASH). After plain scan, the two groups were made multi-phase dynamic enhancement scanning of the pancreas. Mean signal intensities of pancreas of plain scanning and multi-phase dynamic enhancement scanning were measured, the signal to noise(SNR) and contrast to noise (CNR) were calculated, and image quality were assessed. Results: Plain scanning: the SNR of the pancreas in 3D group was 19.2 which was evidently lower than that of the 2D group(22.7, P<0.05)) dynamic enhanced scanning: the SNR or CNR of the pancreas in 3D group were high than that of the 2D group, especially high in the first scanning(P<0.05), the best images of pancreas were obtained in this phase. Conclusion: 3D FLASH is the best dynamic enhanced sequence for pancreas. It offers the better confidence for a more specific and accurate diagnosis and provides more details of the segmental and vascular anatomy to facilitate surgical operation planning.