垂体大腺瘤对后视路影响的功能磁共振成像和弥散张量成像联合研究

目的 采用弥散张量成像(DTI)和功能磁共振成像(fMRI)方法对垂体大腺瘤患者后视路的结构和功能进行评价,分析垂体大腺瘤对视放射和视觉皮层的影响.方法 采用1.5T磁共振扫描仪对23例垂体大腺瘤患者(患者组)及18名健康志愿者(对照组)进行组块设计的fMRI和DTI检查.fMRI刺激内容为全视野黑白翻转棋盘格,对照内容为黑色屏幕中心的白色"+",左右眼分别进行试验.采用SPM2进行fMRI数据后处理,通过组间分析方法分别获得左眼及右眼刺激下患者组与对照组间的激活差异图.DTI扫描采用13个弥散敏感梯度,b值为1000 s/mm2.采用Volume-one软件进行后处理,测量两侧视放射的FA值,分析两组间视放射FA值的差异.结果 在严格控制头动和机械噪声等影响因素后,最终各入组12例.患者组与对照组比较,初级视觉皮层激活范围及强度均明显缩小.且以对侧视觉皮层激活下降为主(P<0.05).患者组左侧及右侧视放射FA值均明显小于对照组(左侧:0.52±0.06比0.58±0.04,t=3.45,P<0.01;右侧:0.50±0.05比0.60±0.04,t=5.77,P<0.01).结论 垂体大腺瘤患者可发生后视路的微观结构改变和功能下降,而联合应用DTI和fMRI有助于早期了解这种脑结构与功能变化.

Combination study of functional magnetic resonance imaging and diffusion tensor imaging on post visual pathways in patients with pituitary macroadenoma

Objective To evaluate the anatomy and function of post visual pathways in patients with pituitary macroadenoma by functional magnetic resonance imaging (fMRI) and diffusion tensor imaging (DTI) and analyze the effect of pituitary macroadenoma on optic radiation and visual cortex. Methods Twenty-three patients with pituitary macroadenoma(patients group) and eighteen matched healthy volunteers (control group) were recmited in this study. Block-designed fMRI and DTI were performed with 1.5 T magnetic resonance scanner. During fMRI examination, black and white check board and white "+" in black screen center were used as stimulus and control respectively. Bilateral eyes in two groups received stimulus individually. The fMRI data were processed with SPM2. Different mappings between two groups during bilateral eyes examination were obtained respectively with inter-group analysis. Thirteen diffusion sensitive directions were used during DTI examination with b value 1000 s/mm2. "Volume-one" software was used to process the DTI data, and FA value of bilateral optic radiation was measured. The difference of the FA value of optic radiation between two groups was compared. Results The numbers of patients selected for group analysis in left and right eye examination were both twelve after head motion and mechanical noise effects were ruled out. Compared to control group, activated extent and intensity of primary visual cortex decreased in patients group, especially in contralateral visual cortex (P<0.05). The FA value of bilateral optic radiation in patients group decreased obviously compared with control group(left: 0.52±0.06 vs 0.58±0.04, t=3.45, P<0.01; fight: 0.50 ± 0.05 vs 0.60 ± 0.04, t=5.77, P<0.01). Conclusions The patients with pituitary macroadenoma may present changed microstructure and decreased function of post visual pathways. Combinated application of fMRI and DTI is an effective method for early detecting the changes of cerebral structures and function.