Diffusion tensor imaging of optic nerve and optic radiation in primary chronic angle-closure glaucoma using 3T magnetic resonance imaging

AIM: To evaluate the value of quantitative diffusion tensor imaging (DTI) in assessing the axonal and myelin damage of the optic nerves and optic radiations in patients with chronic primary angle-closure glaucoma (PACG) by using high-field magnetic resonance (MR) imaging (3T).METHODS:Twenty patients with bilateral chronic PACG and twenty age- and sex matched disease-free control subjects were enrolled. Conventional MRI and DTI were performed on all subjects using 3T MR scanner. Mean diffusivity (MD), fractional anisotropy (FA), axial diffusivities (AD) and radial diffusivities (RD) of each optic nerve and each optic radiation were measured by using post-processing software of DTI studio 2.3, and then compared between left eyes and right eyes and between patients group and control group. The paired-sample t- test were used．RESULTS: There was no abnormality in the shape and signal intensity of the optic nerves and optic radiations in patients group and control group on the conventional MRI. No significant differences were observed in the FA, MD, AD and RD between the right and left optic nerves and optic radiations within patients group and control group (P＞0.05). The optic nerves and optic radiations of patients with chronic PACG, as compared with control subjects, had significantly higher MD, AD, RD and significantly lower FA (P<0.05).CONCLUSION:The diffusivity of optic nerves and optic radiations in chronic PACG group showed abnormal and diffusivity parameters could be used markers of axonal and myelin injury in glaucoma.     

Diffusion tensor imaging of visual pathways in patients with acute and chronic optic neuritis

AIM: To investigate diffusion tensor imaging (DTI) evaluations of visual pathways in patients with acute and chronic optic neuritis (ON), and investigate the correlations between visual disability, retinal nerve fiber layer thickness (RNFLT) and diffusion index changes. METHODS: We performed DTI in 26 patients and 13 healthy controls. Patients had acute ON in 17 eyes, chronic ON in 20 eyes and 15 unaffected eyes. In all participants, the visual afferent system was evaluated with neuro-ophthalmological examinations, optical coherence tomography (OCT), visual evoked potential (VEP), orbital and cranial MRI. RESULTS: Fractional anisotropy (FA) in the optic nerves was lower in patients with acute ON and chronic ON than controls (P=0.28). Mean diffusivity (MD) in the optic nerves, was higher in patients with acute and chronic ON than the unaffected eyes of patients and controls (P<0.01). Retinal nerve fiber layer thickness, P100 amplitude and latency and visual acuity (VA) were significantly different between patient and control groups (P<0.01). Optic chiasm MD values were higher in the patient group compared to the control group (P=0.011). FA and MD measured in the optic tracts significantly were different between groups (P=0.032, P=0.013, respectively). In the correlation analysis, fractional anisotropy in the optic nerves was correlated with P100 latency in acute ON (P=0.021). Mean diffusivity was correlated with RNFLT, visual acuity and P100 latency (P<0.05). Fractional anisotropy was correlated with mean diffusivity and visual acuity, and, mean diffusivity was correlated with P100 amplitude and RNLF thickness in chronic ON (P<0.05). Reduction in visual acuity was correlated with increase in mean diffusivity and decrease in fractional anisotropy (P<0.05). CONCLUSION: DTI can demonstrate abnormalities in a tissue that appears normal in orbital MRI. Our results suggested that DTI derived measurements correlate with visual disability and tissue injury and therefore they are important from a clinical point of view and also in understanding the pathological processes.     

急性和慢性视神经炎患者视觉通路的弥散张量成像分析

目的：急性和慢性视神经炎患者视觉通路的弥散张量成像评估以及视力障碍、视网膜神经纤维层厚度与扩散指数变化的相关性研究。

方法：在26例患者和13例健康对照组中进行扩散张量成像术。患者中17眼患有急性视神经炎,20眼患有慢性视神经炎和15例未受感染眼。所有受试者中,采用神经眼科检查、光学相干断层扫描、视觉诱发电位、眶颅 MRI 等方法对视觉传入系统进行评估。

结果：急性和慢性视神经炎患者视神经中各向异性低于对照组(P=0.28)。急性和慢性视神经炎患者视神经平均扩散率高于患者未受感染眼及对照组(P<0.01)。患者与对照组视网膜神经纤维层厚度、P100 振幅、潜伏期及视力差异均有统计学意义(均P<0.01)。相较于对照组,患者组中视交叉平均扩散率较高(P=0.011)。各组间视束各向异性和平均扩散率测量差异均有统计学意义(分别为P=0.032和P=0.013)。在相关性分析中,急性视神经炎 P100 潜伏期与视神经各向异性相关(r=-0.439,P=0.021)。平均扩散率与视网膜神经纤维层厚度、视力和 P100 潜伏期相关(r=-0.464,-0.334,-0.389; P<0.05)。各向异性与平均扩散率和视力有关,差异均有统计学意义(r=-0.393,0.364; P<0.05), 而慢性视神经炎的平均扩散系数与 P100 振幅和 RNLF 厚度相关(r=-0.412,-0.374; P<0.05)。视力下降与平均扩散率增加和各向异性下降有关(P<0.05)。

结论：弥散张量成像能够显示眼眶MRI看似正常的组织中的异常。研究结果表明, 弥散张量成像的测量与视觉缺陷和组织损伤相关。     

不同时期特发性脱髓鞘性视神经炎视神经扩散张量成像研究

目的探讨不同时期特发性脱髓鞘性视神经炎（IDON）患者视神经扩散张量成像（DTI）指标的变化规律。设计前瞻性病例对照研究。研究对象35例IDON患者及与患者性别、年龄相匹配的35例健康志愿者。方法应用GE1．5T磁共振扫描仪对研究对象进行视神经DTI检查,扫描时间约10分钟,利用FMRIB软件对图像进行校正和配准,利用DTIStudio软件进行视神经DTI参数的测量,分析扩散指标变化。主要指标平均扩散率（MD）、各向异性分数（FA）、最大本征值（λ∥）和横向本征值（λ⊥）。结果与对照组相比,首次受累的急性期IDON视神经DTI指标变化以FA值降低（P=0．000）和入上值升高（P=0．000）为主,缓解期IDON视神经DTI指标变化为FA值降低（P=0．000）,MD值（P=0．004）、λ∥值（P=0．005）和入上值升高（舟0．000）。结论磁共振成像DTI技术可敏感地检测特发性脱髓鞘性视神经炎患者视神经内的水弥散异常,并且视神经DTI指标能够反映不同时期组织的病理生理改变特点及其脱髓鞘程度。     

屈光参差性弱视与斜视性弱视患儿视放射发育情况对比研究:基于扩散张量成像检查

目的　利用扩散张量成像（DTI）检查单眼屈光参差性弱视与斜视性弱视患儿视放射发育情况,比较两种弱视患儿视觉损害发生机制的异同。方法　对屈光参差性弱视组12例左眼弱视患儿、斜视性弱视组12例左眼弱视患儿以及正常对照组15名儿童进行DTI程序扫描,采集所有儿童两侧视放射的各向异性分数（FA）、平均扩散率（MD）,对左右侧视放射FA及MD分别行独立样本t检验,对各组儿童不同部位数据行单因素方差分析,比较两种类型弱视患儿视放射的发育情况。结果　正常对照组儿童的FA及MD右侧均略高于左侧,差异均无统计学意义（均为P>0.05）;屈光参差性弱视组患儿右侧FA（0.469±0.012）高于左侧（0.460±0.013）,右侧MD（0.872±0.015）低于左侧（0.888±0.039）,差异均有统计学意义（均为P<0.05）;斜视性弱视组患儿右侧FA（0.475±0.013）低于左侧（0.496±0.015）,右侧MD（0.871±0.012）高于左侧（0.863±0.015）,差异均有统计学意义（均为P<0.05）。与正常对照组儿童相比,屈光参差性弱视组患儿双侧视放射FA降低、MD升高,差异均有统计学意义（均为P<0.05）;与正常对照组相比,斜视性弱视组患儿双侧视放射FA均降低,右侧视放射MD增高,差异均有统计学意义（均为P<0.05）,左侧视放射MD差异无统计学意义（P＞0.05）。两种类型弱视患儿比较:左侧视放射FA、MD差异均有统计学意义（均为P<0.05）,右侧视放射FA、MD差异均无统计学意义（均为P＞0.05）。结论　DTI可以无创地观察弱视患儿视放射微观结构的改变,为弱视发病机制的研究提供了新的思路和工具。     

Diffusion tensor imaging of horizontal extraocular muscles in patients with concomitant and paralytic esotropia

AIM: To assess metrics of diffusion tensor imagining (DTI) in evaluating microstructural abnormalities of horizontal extraocular muscles (EOM) in esotropia. METHODS: Six adult concomitant esotropia patients, 5 unilateral abducent paralysis patients and 2 healthy volunteers were enrolled. Conventional magnetic resonance imaging (MRI) and DTI were performed on all subjects using 3T MR scanner. Fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD), and radial diffusivity (RD) of medial and lateral rectus muscles were measured and compared between patients group and control group. RESULTS: Medial rectus MD and RD within the adducted eye of concomitant patients was significantly greater than that in unilateral abducent paralysis patients (0.259×10-2 mm2/s vs 0.207×10-2 mm2/s, P=0.014; 0.182×10-2 mm2/s vs 0.152×10-2 mm2/s, P=0.017). Both strabismus patients showed a significantly decreased MD and AD than that obtained in normal controls for lateral rectus muscles (P<0.05). Medial rectus MD of the adducted eye in concomitant strabismus patients was significantly decreased than that in healthy controls (0.259×10-2 mm2/s vs 0.266×10-2 mm2/s, P=0.010). Lateral rectus AD of the adducted eye in concomitant strabismus patients was significantly decreased as compared with that in healthy controls (0.515×10-2 mm2/s vs 0.593×10-2 mm2/s, P=0.013). No statistically significant differences were present between the adducted and fixating eyes in concomitant strabismus patients. CONCLUSION: DTI represents a feasible technique to assess tissue characteristics of EOM. The effects of eye position changes on DTI parameters are subtle. Decreased MD and RD could be evidence for remodeling of the medial rectus muscle contracture. Lower medial and lateral recuts MD of concomitant esotropia patients indicates a thinner fibrous structure of the EOM. Lower MD and AD should be general character of esotropia.     

视网膜色素变性磁共振扩散张量成像研究及其与视野相关性分析

目的　使用磁共振扩散张量成像技术（DTI）研究视网膜色素变性（RP）患者的视神经改变及其与视野检查的相关性。方法　46例RP患者（RP组）和46例健康对照志愿者（对照组）进行了前瞻性研究。所有受试者进行3.0T MRI-DTI扫描检测,使用简化的小视野扩散张量成像（rFOV-DTI）序列推导出单个视神经的各向异性（FA）、平均弥散系数 （MD）、平行扩散系数（λ//）、垂直扩散系数（λ⊥）,获得平均分数FA、平均扩散率和特征值图,用于定量分析。进一步分析视野平均偏差（MDVF）与患者的分数FA、平均扩散率、λ//及λ⊥的相关性。结果　RP组与对照组受试者间年龄和体质量等差异均无统计学意义（均为P>0.05）,而两组之间最佳矫正视力和MDVF差异均具有统计学意义（均为P=0.000）。与对照组相比,RP组患者视神经FA降低,MD、λ//、λ⊥升高,两组之间差异有统计学意义（P<0.001）。RP组患者两侧视神经的FA、MD、λ//和λ⊥与MDVF行相关性分析,视神经FA及λ⊥与MDVF有显著相关性（右侧:r=-0.864、0.719,均为P<0.001;左侧:r=-0 .997、r=0.830,均为P<0.001）;MD与MDVF不相关（右侧:r=-0.026,P=0.866;左侧:r=-0.115,P=0.445）。结论　rFOV-DTI测量值可用于RP患者视神经轴突和髓鞘病变的早期诊断。     

Magnetic resonance diffusion tensor imaging and diffusion tensor tractography of human visual pathway

AIM: To investigate the visual pathway in normal subjects and patients with lesion involved by diffusion tensor imaging (DTI) and diffusion tensor tractography (DTT). METHODS: Thirty normal volunteers, 3 subjects with orbital tumors involved the optic nerve (ON) and 33 subjects with occipital lobe tumors involved the optic radiation (OR) (10 gliomas, 6 meningiomas and 17 cerebral metastases) undertook routine cranium magnetic resonance imaging (MRI), DTI and DTT. Visual pathway fibers were analyzed by DTI and DTT images. Test fractional anisotropy (FA) and mean diffusivity (MD) values in different part of the visual pathway. RESULTS: The whole visual pathway but optic chiasm manifested as hyperintensity in FA maps and homogenous green signal in the direction encoded color maps. The optic chiasm did not display clearly. There was no significant difference between the bilateral FA values and MD values of normal visual pathway but optic chiasm, which the FA values tested were much too low(all P＞0.05). The ONs of subjects with orbital tumors were compressed and displaced. Only one subject had lower FA values and higher MD values. OR of 9 gliomas subjects were infiltrated, with displacement in 2 and disruption in 7 subjects. All OR in 6 meniongiomas subjects were displaced. OR in 17 cerebral metastases subjects all developed displacement while 7 of them had disruption also. CONCLUSION: MR-DTI is highly sensitive in manifesting visual pathway. Visual pathway can be analyzed quantitatively in FA and MD values. DTT supplies accurate three dimensional conformations of visual pathway. But optic chiasm’s manifestation still needs to improve.     

弥散张量成像在急性后部缺血性视神经病变诊断中的应用价值

目的　探讨弥散张量成像（DTI）在急性后部缺血性视神经病变(PION)诊断中的应用价值。 方法　选取30例急性PION患者进行双侧视神经的DTI及视觉诱发电位（VEP）检查,分别测量双眼视神经各向异性分数（FA）、表观扩散系数（ADC）及VEP参数P100潜化期和波幅。采用配对样本t检验对患眼及健眼DTI及VEP参数测量结果进行比较,并采用Pearson分析患眼视神经VEP参数与DTI参数之间的相关性。结果　30例急性PION患者患眼视神经的FA及ADC分别为0.383±0.050、(1596.93±144.07)×10^-6 mm²·s^-1,健眼视神经的FA、ADC分别为0.636±0.080、(1197.80±93.09) ×10^-6 mm²·s^-1;与健眼相比,患眼视神经FA明显下降,ADC升高,差异均有统计学意义（t=-14.53、11.54,均为P<0.01）。患眼与健眼VEP参数P100潜伏期分别为（135.38±7.51）ms、(96.76±6.35）ms,波幅分别为（4.79±1.15）μV、 (10.05±1.45）μV;与健眼相比,患眼VEP参数P100潜伏期明显延长、波幅明显降低,差异均有统计学意义（t=21.67、-15.19,均为P<0.01）。患眼视神经DTI参数FA与VEP参数P100潜伏期呈负相关（r=-0.540, P<0.01）,与P100波幅呈明显正相关（r=0.662,P<0.01）;患眼视神经DTI参数ADC与P100波幅呈明显负相关（r=-0.711,P<0.01）,与P100潜伏期无相关性（r=0.234,P＞0.05）。结论　DTI能够早期发现急性PION患者视神经的弥散障碍,能够为其早期诊断提供影像学依据。     

盲眼患者视神经和视放射磁共振扩散张量成像观察

目的 观察盲眼患者视觉传导通路中视神经和视放射磁共振扩散张量(MR-DTI)扫描像特征.方法 对20例盲眼患者(盲眼组)和20名正常健康者(对照组)行视神经和视放射MR-DTI扫描.应用Volume-one 1.72软件进行后处理,获得黑白各向异性(FA)和方向编码彩色(DEC)图.观察视神经和视放射在FA和DEC图中的信号表达.在DEC图上分别测量并对比分析盲眼组和对照组受检者双侧视神经和视放射的FA、平均扩散率(MD),本征矢量λ∥及λ⊥值.结果 对照组双侧视神经在FA和DEC图均呈高信号,盲眼组双侧视神经在FA和DEC图均呈明显低信号.盲眼组视神经FA和λ∥值均较对照组明显降低,差异有统计学意义(t=16.294,14.660;P值均=0.000);MD和λ⊥值均较对照组明显升高,差异也有统计学意义(t=8.096,8.538;P值均=0.000).两组受检者双侧视放射在FA和DEC图均呈高信号.盲眼组与对照组双侧视放射FA和MD值比较,差异均无统计学意义(左侧:t=1.456、1.811,P=0.152、0.076;右侧:t=0.779、0.073,P=0.440、0.942).结论 盲眼患者双侧视神经MR-DTI呈低信号,双侧视放射MR-DTI呈高信号.     

正常成人前视路高分辨率弥散张量成像研究

目的：检测健康成人前视路弥散张量成像（DTI）参数,探讨其分布特点及影响因素。方法：系列病例研究。选择2015年11月至2016年5月福州总医院体检中心参加体检的健康成人38例,应用3.0T MRI高分辨率弥散张量成像技术对其前视路进行扫描,测定前视路（左右侧视神经中点、视交叉正中点、左右侧视束中点）的各向异性分数（FA）、表观扩散系数(ADC)值,并用弥散张量纤维束成像（DTT）技术重建前视路纤维束,观察纤维束形态结构。采用Pearson相关性分析、两样本t检验及单因素方差分析对数据进行统计学分析。结果：DTI序列FA图、FA编码彩图及ADC图可分辨前视路的结构,DTT能追踪出具有3D效果的视交叉白质纤维束结构。视交叉中点FA、ADC值分别为0.491±0.075和（1.267±0.204）×10-3/mm2,两者呈负相关（r=-0.642,P < 0.00l）。前视路FA 、ADC值与性别和年龄均无相关性。前视路各部位FA、ADC值总体差异均有统计学意义（F=11.575,P < 0.001;F=5.024,P < 0.001）,其中,视交叉处FA值最小（P < 0.001）,ADC值最大（P < 0.001）。结论：健康成人前视路高分辨率DTI参数FA和ADC值敏感可靠。运用高分辨率DTI技术可满意显示变形较小的前视路纤维束结构,定量分析时应注意前视路不同位置的影响。     

Correlation of the measurements of optical coherence tomography and diffuse tension imaging of optic pathways in amblyopia

The aim of this study was to investigate whether a correlation exists between optical coherence tomography (OCT) of retina and diffusion tensor imaging (DTI) of the optic pathway measurements. All subjects underwent OCT measurements of optic nerve head, retinal nerve fiber layer, and macula. Fractional anisotropy (FA) and apparent diffusion coefficient (ADC) values of optic pathways were analyzed using DTI. Prechiasmatic FA values were significantly decreased in unilateral amblyopic group in both affected and sound fellow eyes (p = 0.019 and 0.013), but not in bilateral amblyopic group (p = 0.221) when compared with the control group. ADC values were significantly greater in sound eye in unilateral amblyopic group in prechiasmatic and postchiasmatic regions (p = 0.001 and 0.049). ADC values were also significantly greater in bilateral amblyopic group in postchiasmatic region (p = 0.037). There were no significant differences between the affected eye and sound eye side DTI measurements. There was no significant correlation between prechiasmatic DTI and OCT measurements in affected and sound eyes of unilateral amblyopia group. DTI results demonstrated that there is a functional underdevelopment of the anterior and posterior visual pathways in both affected and sound eye of unilateral amblyopic patients. Significantly reduced FA values in prechiasmatic region where OCT values of retina were normal can be explained by possible micro-structural changes.     

正常眼压性青光眼磁共振扩散张量成像技术（DTI）研究及其与临床分期的相关性

目的　使用磁共振扩散张量成像技术（ｄｉｆｆｕｓｉｏｎｔｅｎｓｏｒｉｍａｇｉｎｇ,ＤＴＩ）研究正常眼压性青光眼（ｎｏｒｍａｌｔｅｎｓｉｏｎｇｌａｕｃｏｍａ,ＮＴＧ）患者视路的改变,探讨其与ＮＴＧ临床分期的相关性。方法　对３０例（６０眼）ＮＴＧ患者（ＮＴＧ组）和３０例（６０眼）健康志愿者（对照组）进行了前瞻性研究。ＮＴＧ临床分期使用Ｈｏｄａｐｐ-Ａｎｄｅｒｓｏｎ-ｐａｒｒｉｓｈ（ＨＡＰ）系统进行分类。所有受试者均进行磁共振ＤＴＩ扫描检测,利用软件处理定量获取视神经、视交叉、视束的各向异性分数（ｆｒａｃｔｉｏｎａｌａｎｉｓｏｔｒｏｐｙ,ＦＡ）、平均扩散系数（ａｖｅｒａｇｅｄｉｆｆｕｓｉｏｎｃｏｅｆｆｉｃｉｅｎｔ,ＡＤＣ）,对比分析ＮＴＧ组与对照组视路改变区域,并检验ＮＴＧ组视路改变程度与临床分期的相关性。结果　与对照组相比,ＮＴＧ组视神经、视交叉及视束的ＦＡ值均明显降低,ＡＤＣ值均明显升高（均为Ｐ＜０．００１）;ＮＴＧ组两侧视神经、视交叉、视束的平均ＦＡ值和ＡＤＣ值均与ＮＴＧ临床分期具有相关性,其中视神经的ＦＡ值与ＮＴＧ临床分期相关性最强（ｒ＝０．７５２,Ｐ＜０．００１）,而视束的ＡＤＣ值与ＮＴＧ临床分期相关性最弱（ｒ＝－０．３３１,Ｐ＜０．００１）。结论　ＤＴＩ有望成为临床诊断ＮＴＧ的可能补充手段。     

磁共振扩散张量及3D-OCT对高眼压症患者视路的初步研究

目的：应用磁共振扩散张量成像(DTI)技术及三维光学相干断层成像(3D-OCT)技术研究高眼压症患者(OHT)视路的微观改变。

方法：纳入我院眼科2016-01/2019-10确诊为双眼OHT的患者26例52眼作为病例组,选取同期年龄、性别均与高眼压组相匹配的健康体检者26例52眼作为对照组。所有受检眼均进行最佳矫正视力检测、中央角膜厚度(CCT)测量、非接触性眼压、视盘3D-OCT扫描检测及视神经、视交叉、视束及视放射DTI检测,OHT患者增加房角镜检查,并对比两组的差异。

结果：OHT组CCT值比正常对照组薄,眼压值较正常对照组增高(均P<0.05)。OHT视盘面积较正常对照组变大,视杯面积增大; 平均青光眼视盘旁神经纤维层(CP-RNFL)厚度、鼻侧RNFL厚度比正常对照组变薄(均P<0.05),上方、下方及颞侧RNFL无差异(均P>0.05)。双侧视神经及视放射的FA值较正常对照组下降(均P<0.05)。两组视交叉、双侧视束FA值、双侧视路ADC值无差异(均P>0.05)。

结论：3D-OCT可以获取CP-RNFL厚度值,视盘的参数; DTI可以重建颅内视觉通路,能早期发现视神经、视交叉、视束、视放射的微观变化。联合3D-OCT及新兴的DTI技术可有效了解OHT患者视路的微观改变,为临床研究高眼压症提供新的思路和研究模式。     

DTI parameters of axonal integrity and demyelination of the optic radiation correlate with glaucoma indices

Background

In glaucoma, damage of retinal ganglion cells may continue to the linked optic radiations. This study investigates the correlation of glaucoma severity indicators with parameters of axonal and myelin integrity of the optic radiations.

Methods

In this observational case–control study, 13 patients with normal-tension glaucoma, 13 patients with primary open-angle glaucoma, and seven control subjects (mean age, 57.6?±?12.5 years) were randomly selected for diffusion tensor imaging (DTI) of the optic radiations. The results of the frequency doubling test (FDT) and the HRT-based linear discriminant functions of Burk (BLDF) and Mikelberg (MLDF) were correlated with the mean of the fractional anisotropy (FA), apparent diffusion coefficient (ADC), and radial diffusivity (RD) of the optic radiations. Multiple correlation analysis, corrected for age, stage of cerebral microangiopathy, diagnosis group, and gender was conducted at increasing thresholds of linear anisotropy (C_L) to reduce mismeasurements because of complex fiber situations.

Results

The best correlations were found for BLDF with FA at C_L threshold 0.3 (0.594, p?=?0.001), with ADC at C_L 0.4 (?0.511, p?=?0.005), and with RD at C_L 0.4 (?0.585, p?=?0.001). MLDF correlated with FA at C_L 0.4 (0.393, p?=?0.035). The FDT score correlated with FA at C_L 0 (?0.491, p?=?0.007) and with RD at C_L 0 (?0.375, p?=?0.045).

Conclusions

In glaucoma, DTI-derived parameters of the axonal integrity (FA, ADC) and demyelination (RD) of the optic radiation are linked to HRT-based indices of glaucoma severity and to impairment of the spatial-temporal contrast sensitivity.     

磁共振扩散张量成像在缺血性视神经病变中的应用

目的初步探讨磁共振扩散张量成像（MR-DTI）在缺血性视神经病变的检测价值。方法对18例单侧缺血性视神经病变和20例健康成年人分别行3.0 MR-DTI检测,研究缺血视神经、健侧及对照组视神经的各向异性（FA）、表现扩散系数（ADC）、Trace W、E1、E2、相对各向异性指数（RA）、容积率（VR）值,并进行比较。结果缺血性视神经病变患者FA、ADC、Trace W、E1、E2、RA、VR值分别为0.259±0.057、（1 510±85）×10-6mm2/s、52±10、（1 884±139）×10-6mm2/s、（1 476±302）×10-6mm2/s、0.216±0.049、0.919±0.023。健侧视神经相应DTI参数值分别为0.574±0.018、（1 025±67）×10-6mm2/s、67±8、（1 661±103）×10-6mm2/s、（962±182）×10-6mm2/s、0.548±0.026、0.624±0.030。正常成人视神经相应DTI参数值分别为0.585±0.020、（935±133）×10-6mm2/s、69±15、（1 654±157）×10-6mm2/s、（752±118）×10-6mm2/s、0.561±0.026、0.617±0.048。患侧视神经与健侧、对照组视神经相比,ADC、E2、VR值升高,FA值、RA值均降低,差异有统计学意义（P〈0.01）。患侧视神经平均Trace W值与健侧（P=0.003）、对照组视神经（P=0.005）相比均升高,差异有统计学意义。患侧视神经E1值较健侧、对照组视神经升高,差异均有统计学意义（P=0.001）。结论MR-DTI可以作为缺血性视神经病变敏感、可靠的检测方法。     

Diffusion Tensor Imaging of Visual Pathway Abnormalities in Five Glaucoma Animal Models

PurposeTo characterize the visual pathway integrity of five glaucoma animal models using diffusion tensor imaging (DTI).MethodsTwo experimentally induced and three genetically determined models of glaucoma were evaluated. For inducible models, chronic IOP elevation was achieved via intracameral injection of microbeads or laser photocoagulation of the trabecular meshwork in adult rodent eyes. For genetic models, the DBA/2J mouse model of pigmentary glaucoma, the LTBP2 mutant feline model of congenital glaucoma, and the transgenic TBK1 mouse model of normotensive glaucoma were compared with their respective genetically matched healthy controls. DTI parameters, including fractional anisotropy, axial diffusivity, and radial diffusivity, were evaluated along the optic nerve and optic tract.ResultsSignificantly elevated IOP relative to controls was observed in each animal model except for the transgenic TBK1 mice. Significantly lower fractional anisotropy and higher radial diffusivity were observed along the visual pathways of the microbead- and laser-induced rodent models, the DBA/2J mice, and the LTBP2-mutant cats compared with their respective healthy controls. The DBA/2J mice also exhibited lower axial diffusivity, which was not observed in the other models examined. No apparent DTI change was observed in the transgenic TBK1 mice compared with controls.ConclusionsChronic IOP elevation was accompanied by decreased fractional anisotropy and increased radial diffusivity along the optic nerve or optic tract, suggestive of disrupted microstructural integrity in both inducible and genetic glaucoma animal models. The effects on axial diffusivity differed between models, indicating that this DTI metric may represent different aspects of pathological changes over time and with severity.     

单眼弱视治疗前后视放射的扩散张量成像研究

目的：利用磁共振扩散张量成像(diffusion tensor imaging,DTI)技术研究单眼弱视儿童治疗前后视放射的变化及其神经机制。

方法：选择18例左眼屈光参差性弱视儿童经过为期9mo的弱视治疗,对治疗前后的视放射进行DTI检查,比较分析治疗前后视放射的各向异性分数(fractional anisotropy, FA)值和表观扩散系数(apparent diffusion coefficient, ADC)值的变化。

结果：治疗后两侧视放射的FA 值均高于治疗前(P<0.05),ADC值均低于治疗前(P<0.05)。右侧视放射治疗前后FA 值和ADC值的变化均大于左侧视放射(P<0.05)。

结论：单眼弱视儿童经过有效的弱视治疗后,两侧视放射的神经纤维均得到不同程度的改善。     

高度近视合并青光眼患者视神经纤维层厚度的变化

目的:通过光学相干断层成像(OCT)检测高度近视合并青光眼患者视神经纤维层厚度的变化规律。方法:选取2017-01/12于我院进行治疗的高度近视合并青光眼患者80例160眼作为观察组,并选择同期于我院进行体检的健康志愿者60例120眼作为对照组。采用OCT分析所有受检者视神经纤维层厚度。结果:与对照组受检者相比,观察组患者鼻侧、颞上、鼻下、鼻上、颞下及全周平均视神经纤维层厚度均降低,而颞侧视神经纤维层厚度升高(P<0.05),且观察组中屈光度-10.00^-11.00D的患者鼻侧、颞上、鼻下、鼻上、颞下及全周平均视神经纤维层厚度均显著高于屈光度≥-12.00D的患者(P<0.05)。Spearman相关分析结果显示,观察组患者屈光度的绝对值与鼻侧、颞上、鼻下、颞下及全周平均厚度视神经纤维层厚度呈负相关,与颞侧视神经纤维层厚度呈正相关。结论:高度近视合并青光眼患者除颞侧外各象限视神经纤维层变薄。     

Diameter of the optic nerve in idiopathic optic neuritis and in anterior ischemic optic neuropathy

Purpose: There is considerable overlap in the clinical profile of patients with idiopathic optic neuritis(ON) and anterior ischemic optic neuropathy (AION). We tested the hypothesis that the retrobulbar diameter of the optic nerve may be a criterion for the differential diagnosis between ON and AION. Methods: The diameter of the optic nerve was measured by B-scan ultrasonography with the eye in an abducted position. Only patients with a unilateral optic neuropathy were included, 16 ON patients (mean age 24years, 5 with and 11 without disc swelling) and 9patients with AION (mean age 72 years). As controls for the ON patients 10 young normal subjects (mean age25 years) and as controls for the AION patients 10elderly subjects with eye problems not related to the optic nerve (mean age 76 years) were examined. Results: In the ON patients with disc swelling the diameter of the optic nerve was 5.4 ± 0.5 mm in the affected and 3.0 ± 0.3 mm in the unaffected side. This difference was significant (Wilcoxon-test, p = 0.043). In the ON patients without disc swelling the diameter of the optic nerve was 4.4 ± 0.4 mm in the affected and 3.0 ± 0.3 mm in the unaffected side. This difference was significant (Wilcoxon-test, p = 0.003). In the AION patients the diameter of the optic nerve was 3.0 ± 0.3 mm on the affected and2.8 ± 0.4 mm on the unaffected side. This difference was not significant (Wilcoxon-test, p =0.093). Comparing the optic nerves with ON and AION to those of the controls, the diameter was significantly enlarged in the nerves with ON and normal in the nerves with AION (one factor repeated ANOVA). Conclusion: The diameter of the optic nerve is increased in ON without disc swelling and even more so in ON with disc swelling. The enlargement is probably due to edema of the nerve itself, not the surrounding subarachnoidal space. In AION, the diameter of the optic nerve is normal. Measuring the diameter of the optic nerve by B-scan ultrasonography is particularly useful in the differential diagnosis between ON with disc swelling and AION. This revised version was published online in August 2006 with corrections to the Cover Date.