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目的探讨在1.5T MR上应用头线圈进行垂体大腺瘤扩散加权成像(DWI)的可行性,并优化序列参数,探索理想的层厚和b值。方法随机选取15名健康志愿者及15例垂体大腺瘤患者,测定b值分别为300、800、1200s/mm2时的信号强度、背景噪声及垂体瘤的表观扩散系数(ADC)值。比较不同b值时正常垂体的信号强度、质量指数及信噪比的差异;同一b值时垂体大腺瘤平均ADC值的差异。结果 (1)正常垂体DWI图像各b值时的信号强度随b值增加而显著降低(P<0.01),而噪声则与b值无关(P>0.05);(2)b=800s/mm2时,垂体大腺瘤的平均ADC值为(1.032±0.059)×10-3mm2/s,正常垂体平均ADC值为(4.025±0.382)×10-3mm2/s,两者差异有统计学意义(P<0.05);(3)b=800s/mm2时,层厚3、4mm对垂体瘤显示评分明显高于2mm(P<0.05),层厚4mm时图像伪影比3mm和2mm明显(P<0.05)。结论 1.5T MR行垂体大腺瘤DWI是可行的。以层厚3mmb值为800s/mm2的图像质量为佳。
Objective To investigate the feasibility of using DWI with a head coil on 1.5T MR and to optimize the sequence parameters and to explore the ideal layer thickness and b value. Methods Fifteen healthy volunteers and 15 patients with pituitary adenoma were randomly selected. The signal intensity, background noise and apparent diffusion coefficient (ADC) of pituitary adenoma were measured at b values of 300, 800 and 1200 s / mm2, respectively. The difference of signal intensity, quality index and signal-to-noise ratio of normal pituitary at different b values were compared. The difference of average ADC value of pituitary adenoma at the same b value was compared. Results (1) The signal intensity of each b value of normal pituitary DWI images was significantly decreased with the increase of b value (P <0.01), while the noise was not related to b value (P> 0.05). (2) When b = 800s / (1.032 ± 0.059) × 10-3mm2 / s in normal pituitary adenomas and (4.025 ± 0.382) × 10-3mm2 / s in normal pituitary adenomas, respectively (P < (P <0.05). (3) When the thickness of 4 mm for b = 800s / mm2, the thickness of the pituitary tumor was significantly higher than 2mm (P <0.05) . Conclusion 1.5T MR pituitary adenoma DWI is feasible. It is better to use a layer thickness of 3 mmb at an image quality of 800 s / mm 2.