Parkinson disease (PD) is a chronic progressive neurodegenerative disorder characterized pathologically by early loss of neuromelanin (NM) in the substantia nigra pars compacta (SNpc) and increased iron deposition in the substantia nigra (SN). Degeneration of the SN presents as a 50 to 70% loss of pigmented neurons in the ventral lateral tier of the SNpc at the onset of symptoms. Also, using magnetic resonance imaging (MRI), iron deposition and volume changes of the red nucleus (RN), and subthalamic nucleus (STN) have been reported to be associated with disease status and rate of progression. Further, the STN serves as an important target for deep brain stimulation treatment in advanced PD patients. Therefore, an accurate in-vivo delineation of the SN, its subregions and other midbrain structures such as the RN and STN could be useful to better study iron and NM changes in PD. Our goal was to use an MRI template to create an automatic midbrain deep gray matter nuclei segmentation approach based on iron and NM contrast derived from a single, multiecho magnetization transfer contrast gradient echo (MTC-GRE) imaging sequence. The short echo TE = 7.5 ms data from a 3D MTC-GRE sequence was used to find the NM-rich region, while the second echo TE = 15 ms was used to calculate the quantitative susceptibility map for 87 healthy subjects (mean age ± SD: 63.4 ± 6.2 years old, range: 45-81 years). From these data, we created both NM and iron templates and calculated the boundaries of each midbrain nucleus in template space, mapped these boundaries back to the original space and then fine-tuned the boundaries in the original space using a dynamic programming algorithm to match the details of each individual's NM and iron features. A dual mapping approach was used to improve the performance of the morphological mapping of the midbrain of any given individual to the template space. A threshold approach was used in the NM-rich region and susceptibility maps to optimize the DICE similarity coefficients and the volume ratios. The results for the NM of the SN as well as the iron containing SN, STN, and RN all indicate a strong agreement with manually drawn structures. The DICE similarity coefficients and volume ratios for these structures were 0.85, 0.87, 0.75, and 0.92 and 0.93, 0.95, 0.89, 1.05, respectively, before applying any threshold on the data. Using this fully automatic template-based deep gray matter mapping approach, it is possible to accurately measure the tissue properties such as volumes, iron content, and NM content of the midbrain nuclei.

目的:使用体模评价两种CT机型两组管电压下的图像质量.方法:采用西门子SOMATOM Force CT和飞利浦IQon Spectral CT分别扫描Catphan500图像质量控制体模的CTP528和CTP515组件.对比研究两台机器4组图像,分别为Force120kVp,Force140kVp,IQon120kvp以及IQon140kvp图像;4组图像均为20mGy剂量.评价指标包括高对比度分辨率[CTP528最佳线对(1～21p/cm)]、低对比度分辨率[CTP515 1％浓度下最小孔径(直径2～15mm)]、图像噪声、对比噪声比(CNR)和信噪比(SNR).结果:Force120kVp和IQon120kvp两组图像的高对比度分辨率最高(均为61p/cm).4组图像低对比度分辨率相同(最小孔径均为5mm).Force120kVp 图像噪声最小(2.500±0.000),且 SNR 最高(30.806±1.398);噪声和 SNR 在 4 组图像间差异具有统计学意义.IQon140kvp图像的CNR最高(3.325±0.300),各组图像间差异无统计学意义.结论:不同机型不同管电压下的图像质量存在差异;两台机器120kVp图像的对比度分辨率略好于140kVp图像;Force CT的120kVp图像相比140kVp图像的图像噪声更小,而IQon Spectral CT的两组图像噪声参数无显著差别.

目的:对比研究国内外不同品牌及型号医用磁共振成像(MRI)设备在颈椎磁共振常规序列的图像质量.方法:回顾性分析全国25家医疗机构及中心,基于7种国内外品牌9种机型的医用MRI设备所采集的447例患者颈椎MRI扫描有效图像资料.按照所使用设备的不同,将扫描图像分为0.3～0.5 T、1.5 T及3.0 T组,相同场强组中以设备品牌为亚组.基于美国放射学会(ACR)指南内容,采用李克特五级量表评分法对各序列图像进行临床图像质量评价,并进行组间对比.结果:3.0 T的MRI图像质量各项指标4个必需序列的15个评价指标评分最优,1.5 T次之,其差异有统计学意义.在相同场强MRI设备样本中,国产设备与国外进口品牌MRI设备颈椎MRI图像质量组间对比,部分指标差异无统计学意义,部分指标优于国外进口品牌,差异有统计学意义.结论:3.0 T的MRI设备颈椎MRI成像临床图像质量明显优于1.5 T及其以下的低场设备.在相同场强下,国产MRI设备部分临床图像质量指标与国外进口品牌相近.

目的:探讨基于可变形图像配准(deformableregistration algorithms,DRA)算法的心肌形变分析在肥厚型心肌病(hypertrophic cardiomyopathy,HCM)中的诊断及预后预测价值.方法:回顾性收集本院确诊的HCM患者23例,另招募23名年龄性别匹配的健康志愿者(对照组),均行心脏MRI扫描.HCM组按有无心肌延迟强化(late gadoli-nium enhancement,LGE)分为LGE(+)组和LGE(-)组.采用基于DRA算法的TrufiStrain软件进行心肌形变分析,测量整体径向应变峰值(global peak radial strain,GPRS)、整体环向应变峰值(global peak circumferential strain,GPCS)和整体纵向应变峰值(global peak longitudinal strain,GPLS)以及心尖部、中部和基底部的径向应变峰值(peak radial strain,PRS)、环向应变峰值(peak circumferential strain,PCS)和纵向应变峰值(peak longitudinal strain,PLS),探讨心肌形变参数在HCM中的诊断效能及其与心室壁厚度、LGE间的关系.结果:除心尖部PCS外,HCM组的GPRS、GPCS、GPLS及基底部和中部PRS、PCS、PLS,以及心尖部的PRS、PLS均明显低于对照组(P<0.05),而HCM组的整体及各部分3个方向(环向、纵向、径向)的应变率比值均明显小于对照组(P<0.05),且LGE(-)组及对照组各部分的PRS、PCS、PLS及3个方向的舒张早期和晚期应变率比值[径向应变率比值(ratio of radial strain rate during early and late diastole,REL),环向应变率比值(ratio of circumferential strain rate during early and late diastole,CEL)和纵向应变率比值(ratio of longitudinal strain rate during early and late diastole,LEL)]均大于LGE(+)组(P<0.05).GPRS、GPCS、GPLS、REL、CEL、LEL均与左心室心肌最大厚度明显相关(P<0.05).GPRS、GPCS、GPLS、REL、CEL及LEL诊断HCM的曲线下面积分别为0.686、0.905、0.921、0.972、0.974及0.917,GPRS、GPCS、GPLS、REL、CEL及LEL预测HCM患者是否有LGE的曲线下面积均大于0.871.结论:基于DRA的心肌形变分析在诊断HCM、预测HCM患者发生LGE中具有重要价值,且与心肌厚度密切相关.

颗粒随机堆积问题是物理和工程领域的热门问题.椭球颗粒随机堆积体系作为球形体系的拓展,增加了旋转自由度,从而表现出更复杂的性质,由于椭球颗粒比球形颗粒更类似于自然界中普遍存在的非规则颗粒,因此其研究其有重要的实用价值.研究三维颗粒堆积结构问题一般需要CT成像技术,本文介绍了如何利用医用CT对三维椭球随机堆积体系进行成像研究的技术细节,包括如何通过图像处理的方法获取椭球颗粒的空问位置、取阳和体积,如何利用接触数标度函数拟合的方法得到近邻颗粒问的接触信息等.本文的研究内容和方法为利用各种X射线CT成像方法研究三维颗粒体系提供了技术参考.

A total of 100 Parkinson’s disease (PD) patients and 100 age- and sex-matched healthy controls (HCs) were scanned using a single 3D gradient echo magnetization transfer sequence. We developed an automatic substantia nigra (SN) subregions segmentation approach to get neuromelanin (NM) and iron measurements in the SN. These measures along with their overlap region volume and the nigrosome-1 (N1) sign showed reliable results indicative of promising diagnostic biomarkers to differentiate PD patients from HCs.