原发性慢性闭角型青光眼视神经MR扩散张量成像的研究

目的 探讨视神经MR DTI在研究原发性慢性闭角型青光眼所致视神经改变的临床应用价值.方法 对25例原发性慢性闭角型青光眼患者(病变组,4例为单眼发病,其余为双眼发病,共46只眼,其中右眼24只,左眼22只)和20名正常人(对照组)分别行3.0T视神经MRI和DTI检查,对比两组间各向异性(FA)、平行扩散率(λ∥)、垂直扩散率(λ⊥)、平均扩散率(MD)值差别.病变组与对照组同侧视神经比较、病变组内左与右侧视神经间比较,分别采用两独立样本t检验和配对t检验.结果 病变组6例患者8条视神经MRI表现为轻微变细,视神经鞘膜腔轻微增宽.病变组24条右眼视神经DTI的FA、λ∥、λ⊥、MD值分别为(0.27 ±0.09)×10-3、(2.30 ±0.26) ×10-3、(1.55 ±0.35)×10-3、(1.80±0.31) ×10-3mm2/s,22条左眼视神经分别为(0.24 ±0.09)×10-3、(2.25 ±0.41) ×10-3、(1.61 ±0.46) ×10-3、(1.82±0.47)×10-3 mm2/s；对照组20条右眼视神经DTI的FA、λ∥、λ⊥、MD值分别为(0.57±0.04) ×10-3、(1.78 ±0.24) ×10-3、(0.68±0.11) ×10-3、(1.01 ±0.08)×10 -3mm2/s,20条左眼视神经分别为(0.59 ±0.03) ×10-3、(1.76 ±0.13)×10-3、(0.63 ±0.07)×10-3、( 1.04±0.15)×10-3 mm2/s.与对照组比较,病变组FA值降低、λ∥、λ⊥、MD值升高,差异均有统计学意义(P值均＜0.05)；病变组内左、右侧视神经相互比较,差异无统计学意义(P＞0.05).结论 DTI可以发现原发性慢性闭角型青光眼视神经扩散异常,并可定量推测视神经病理变化.

MR diffusion tensor imaging of optic nerve in patients with primary chronic angle-closure glaucoma

Objective To investigate the value of MR diffusion tensor imaging (DTI) of optic nerve in the estimation of optic nerve changes of primary chronic angle-closure glaucoma (PCACG).Methods Twenty-five patients with PCACG including monocular involvement in 4 patients and binocular involvement in 21 patients and involving 46 eyes in which 24 right eyes and 22 1eft eyes,and 20 normal volunteers were enrolled.Conventional MRI and DTI were performed on all subjects using Magnetom Tim 3.0 T MRI.Fractional anisotropy( FA),mean diffusivity ( MD),axial diffusivities ( λ ∥ ) and radial diffusivities ( λ ⊥ )were measured and then compared between patients group and control group and between left eyes and right eyes.Two independent samples t-test and paired t-test were used.Results On conventional MRI,thinner optic nerve with vaginal cavity widened slightly was found in 8 optic nerves of 6 patients.The value of FA,λ∥,λ⊥ and MD of 24 right optic nerves in patient group was(0.27 ± 0.09) × 10-3,(2.30 ±0.26) × 10 - 3,( 1.55 ± 0.35 ) × 10 - 3,and ( 1.80 ± 0.31 ) × 10 - 3 mm2/s respectively and that of 22 left optic nerves was (0.24 ± 0.09) × 10-3,(2.25 ± 0.41) × 10-3,(1.61 ± 0.46) × 10-3,and (1.82 ±0.47) × 10-3mm2/s respectively.The FA of optic nerve in patient group was lower than that of control group (P ＜0.05 ),while the meanλ∥,λ ⊥ and MD values was obviously higher than control group (P ＜ 0.05).There was no significant difference between right and left optic nerves in patient gro up ( P ＞0.05).Conclusions DTI could detect abnormality and provide information about the pathological process of optic nerve in patients with PCACG.