涎腺导管癌CT及MRI影像特征分析

目的观察涎腺导管癌(salivary duct carcinoma, SDC)患者的CT、MRI表现,探讨其影像学特征。方法回顾性分析经手术组织病理证实的32例SDC患者的影像学、临床及病理资料,观察其部位、大小、形态、边界、与周围组织关系、密度、信号、强化方式、钙化、囊变及转移情况等。结果 32例SDC患者中,31例病灶为单发,17例位于腮腺,8例位于颌下腺,2例位于鼻窦,2例位于眼眶内,1例位于郏部,1例位于舌下腺;1例病灶为多发,位于腮腺。肿瘤最大直径1.5~7.2 cm,中位直径3.0 cm;肿瘤呈弥漫性生长11例,局灶性生长21例;24例边界清楚,8例边界不清;病灶可侵犯咽旁间隙、软腭、面神经、听神经、皮肤、周围肌肉及骨质;有淋巴结转移者15例(47%),肺转移1例。MRI显示肿瘤实性部分T1WI以等、低信号为主,T2WI呈混杂高信号影,囊变坏死区呈T1WI低信号、T2WI高信号影。CT显示肿瘤密度不均,呈等、低密度为主者15例,呈高密度者4例,7例可见钙化。增强扫描显示实性部分呈中度-明显强化。结论 SDC多为单发,易发生囊变坏死及钙化,侵袭性强,淋巴结转移多见,了解其影像学表现有助于提高术前诊断的准确率。     

自适应统计迭代重建在儿童颞骨低剂量CT扫描中的应用研究

目的 对比宝石高分辨CT及64排容积CT扫描的辐射剂量,评价自适应统计迭代重建技术（ASiR）对儿童颞骨低剂量扫描的价值。方法 将60例因先天性耳聋的患儿按照性别、年龄及就诊顺序分为A组和B组,每组30例。A组采用Discovery HD CT 750行低剂量颞骨CT扫描,预设噪声指数（NI）为12,使用自适应流计迭代重建（ASiR）对原始图像进行后处理重建,ASiR权重值设为40％。B组采用Lightspeed VCT 64进行扫描,NI为8,使用滤波反向投影（FBP）对图像进行重建。分别记录各组CT扫描的最大电流、最小电流及容积CT剂量指数（CTDI_vol）,测量并记录有效剂量及临近颞骨密度相对较均匀的脑组织客观噪声,同时评价和记录图像的主观图像质量。使用SPSS 18.0统计软件对各组数据进行统计学分析。结果 A组的平均管电流和CTDI_vol值分别为（110.40±21.72） mA和（26.43±3.48） mGy,B组分别为（168.56±24.36） mA 和（39.66±4.17） mGy,两组比较差异有统计学意义（t=-9.76、-13.31, P < 0.05）。两组患儿临近颞骨密度相对较均匀的脑组织NI分别为：A组（33.13±2.68）、B组 （33.79±2.93）,两组间差异无统计学意义（P > 0.05）。A、B两组图像主观评分分别为 （4.06±0.03）和（4.05±0.03）;两组比较差异无统计学意义（P > 0.05）。 结论 在获得同样质量图像的前提下,与GE Lightspeed VCT 64的FBP方法相比,GE Discovery HD CT 750采用40％ASiR方法并提高4个单位NI值的扫描方案可有效减低儿童颞骨CT扫描的辐射剂量。     

Quantitative assessment of optic nerve in patients with Leber’s hereditary optic neuropathy using reduced field-of-view diffusion tensor imaging

PurposeTo quantitatively analyze the optic nerve alterations in chronic Leber’s hereditary optic neuropathy (LHON) using reduced field-of-view diffusion tensor imaging (rFOV-DTI) and evaluate the correlation of diffusion parameters with visual functional and peripapillary retinal nerve fiber layer (RNFL) thickness.MethodsTwenty-five patients (50 affected optic nerves) with chronic LHON and 28 healthy controls (56 normal optic nerves) were enrolled. The rFOV-DTI was performed in the bilateral optic nerves for all the subjects. The fractional anisotropy (FA), mean diffusivity (MD), principal eigenvalue (λ//), and orthogonal eigenvalue (λ⊥) were calculated for quantitative analysis. Visual field (VF) and visual acuity (VA) were measured in all subjects. The peripapillary RNFL thickness was assessed using optical coherence tomography (OCT). The correlation of DTI diffusion parameters with visual function and peripapillary RNFL thickness was evaluated.ResultsCompared with optic nerves in the control group, the mean FA was significant decreased (P < 0.005), and the mean MD, λ//and λ⊥ significant increased (P < 0.005). The average and temporal peripapillary RNFL thickness were significantly thinned in LHON patients. There was a significant correlation between optic nerve FA and VA, mean deviation of visual field (MD_VF) (P < 0.005). Also, optic nerve FA correlated significantly with average RNFL thickness (P < 0.05) but not with MD, λ//and λ⊥ (P > 0.05). However, none of the DTI parameters correlated with age and disease duration (P > 0.05).ConclusionsOur study has demonstrated that rFOV-DTI could provide information of optic nerve damage in chronic LHON, and can serve as technique for detecting and evaluating pathological changes in the optic nerve in LHON.