高弥散敏感因子(b)值DWI 及ADC 值对前列腺癌与前列腺炎鉴别诊断的应用对比分析

目的:探讨高弥散敏感因子(b)值扩散加权成像(DWI)及表面扩散系数(ADC)在前列腺癌和前列腺炎鉴别诊断的应用价值。方法:回顾性分析2018年4月—2019年9月经手术、活检病理或随访证实最终诊断的前列腺癌21例(25个病灶)和前列腺炎20例(28个病灶)。所有患者于手术或穿刺前行MRI扩散加权成像,b值选择1000、2000、3000 s/mm^2,观察不同b值的DWI及ADC值对前列腺癌和前列腺炎的定性诊断准确率。比较不同b值的DWI及ADC值在前列腺癌和前列腺炎病变诊断中有无统计学意义,分别计算出不同的b值DWI诊断前列腺癌和前列腺炎的诊断效能。结果:b值选择为1000、2000、3000 s/mm^2 DWI在前列腺癌和前列腺炎病变鉴别诊断中均有统计学意义(P<0.05),b值选择1000、2000、3000 s/mm^2在DWI诊断前列腺癌和前列腺炎的特异性、准确度分别为71.4%、84.9%,92.9%、92.5%,100.0%、96.2%,b值选择2000、3000 s/mm^2 DWI诊断前列腺癌和前列腺炎的特异性、准确度高于b值选择1000 s/mm^2 DWI。b值选择为1000、2000、3000 s/mm^2时,前列腺癌的ADC值均低于前列腺炎,并且b值选择为1000、2000、3000 s/mm^2所测得的ADC值前列腺癌和前列腺炎组间差异有统计学意义(P<0.05)。结论:采用高b值DWI及ADC值可以准确区分前列腺癌和前列腺炎,具有良好的定性诊断价值。     

体素内不相干运动及超高b值扩散峰度成像对前列腺癌的诊断价值研究

目的 探讨体素内不相关运动(IVIM)及超高b值扩散峰度成像(DKI)模型参数对前列腺癌的诊断价值以及对Gleason评分的预测作用。方法 2017年2月至2018年6月,共45例前列腺疾病患者进行多b值MRI检查,仪器采用Prisma MRI 3.0T。采用后期处理软件分析IVIM模型(b=0、50、100、150、200、400、800、1 200),获得纯扩散系数(Dt)、伪扩散系数(Dp)、灌注分数(f);分析DKI模型(b=0、400、800、1 200、2 000、3 000、4 000),获得峰度校正的扩散系数(D)、无量纲度量表观峰度系数(K)。经病理证实前列腺癌26例,良性病变19例,分别计算前列腺癌及良性病变的Dt值、Dp值、f值及D值和K值参数。根据前列腺病理分析所确定的Gleason评分(≥7为高分,7为低分),使用这些参数鉴别病变等级。结果 在前列腺癌中IVIM模型Dt值为0.60±0.15,明显低于良性病变(1.19±0.23)(P0.001);而前列腺癌及良性病变的Dp值和f值差异无统计学意义。在前列腺癌和良性病变中DKI模型D值分别为0.78(0.68～0.88)及1.68(1.44～1.81),K值分别为0.95(0.89～1.00)及0.57(0.53～0.67),差异有统计学意义(P0.001)。另外,DKI中K值可以显著区分在Gleason评分高分(1.03±0.12)及低分(0.61±0.09)前列腺癌病变等级,有助于诊断有临床意义前列腺癌。ROC评估诊断效能发现,Dt、D和K值的诊断效能明显优于Dp和f值。结论 IVIM和超高b值DKI模型可能对前列腺癌有重要的鉴别诊断价值,并对Gleason评分有一定的预测作用。     

全麻手术患者围术期下肢有创血压与无创血压的相关性分析

目的比较全麻手术患者下肢踝部无创血压与同侧足背动脉有创血压的差异。方法选择神经外科择期手术的患者24例,ASAⅠ~Ⅲ级,均行静脉全身麻醉。术中同时监测下肢踝部无创袖带血压和同侧足背动脉置管有创血压。采用Bland-Altman法分析两种血压测量方法的一致性。结果下肢无创SBP、DBP均明显高于有创SBP、DBP(P<0.05)。有创血压值与无创血压值之间具有较好的相关性,SBP与DBP的Pearson相关系数分别为0.833和0.757(P<0.01)。有创SBP与无创SBP的平均偏差-3.8mm Hg,一致性界限为-24.0~16.4mm Hg,有创DBP与无创DBP的平均偏差-5.4mm Hg,一致性界限为-18.1~7.4mm Hg。结论围手术期监测患者下肢血压时应该考虑到无创袖带和动脉内置管两种测压方法所得血压值存在一定的差异。     

弥散张量成像鉴别诊断肾透明细胞癌与肾盂移行细胞癌

目的评价MRI弥散张量成像(DTI)在肾透明细胞癌(ccRCC)与肾盂移行细胞癌(TCC)鉴别诊断中的价值。方法回顾性分析行腹部MR检查、经病理证实为ccRCC及TCC的患者38例(ccRCC 29例,TCC 9例)。患者均行MR T1W脂肪抑制和T2W脂肪抑制序列扫描、LAVA增强扫描、DTI序列扫描(b=0、600s/mm~2)。由2名放射科医师采用AW 4.4工作站采用Functool后处理软件进行图像分析和测量。采用组内相关系数(ICC)检验2名察者所测数据的一致性。ccRCC和TCC ADC值及FA值的比较采用独立样本t检验。采用ROC曲线分析ADC值、FA值对ccRCC与TCC的鉴别诊断效能。结果 2名观察者测量各参数一致性良好(ICC值均0.75)。ccRCC的ADC值[(2.03±0.49)×10~(-3) mm~2/s]高于TCC[(1.57±0.43)×10~(-3 )mm~2/s;P=0.015)],但ccRCC的FA值(0.24±0.10)低于TCC(0.42±0.22);P=0.002)。ADC值曲线下面积0.761(P0.05),敏感度和特异度分别为79.3%、77.8%,阈值为1.59×10~(-3) mm~2/s。FA值曲线下面积为0.762(P0.05),敏感度和特异度分别为66.7%、93.1%,阈值为0.326。结论 MR DTI可有效鉴别ccRCC和肾盂TCC,其中FA值对鉴别两者的特异度较高。     

神经外科手术中桡动脉与足背动脉脉压变异度的一致性分析

目的探讨在神经外科手术中桡动脉与足背动脉的脉压变异度的一致性。方法选择神经外科择期开颅手术患者25例,全麻气管插管后,记录麻醉诱导后20min、去骨瓣即刻、剪开硬膜即刻、上骨瓣时的桡动脉脉压变异度(PPV1)与足背动脉脉压变异度(PPV2)。VT设置为8ml/kg,采用Bland-Altman法分析PPV1与PPV2的一致性。结果 Bland-Altman分析显示:PPV1与PPV2麻醉诱导后20 min平均偏差0.5%(-1.9%~2.8%);去骨瓣即刻平均偏差-0.5%(-3.8%~2.9%);剪开硬膜即刻平均偏差-0.1%(-3.2%~3.0%);上骨瓣时平均偏差0.1%(-2.4%~2.6%)。结论与桡动脉脉压变异度一样,足背动脉脉压变异度对于神经外科开颅手术中的容量监测及容量治疗有指导意义。     

幕上肿瘤患者肿瘤侧和非肿瘤侧额部脑电双频指数的一致性

目的比较神经外科幕上肿瘤切除术中肿瘤侧和非肿瘤侧额部脑电双频指数(bispectral index,BIS)是否具有一致性。方法择期行幕上肿瘤手术患者35例,男16例,女19例,年龄18~65岁,ASAⅡ或Ⅲ级。每位患者肿瘤侧和非肿瘤侧额部同时放置BIS电极。麻醉方法:静脉快速诱导,全凭静脉维持麻醉。记录麻醉手术过程中诱导前期、剪硬膜前、切瘤中、清醒后期四个阶段肿瘤侧和非肿瘤侧的BIS数据行Bland-Altman分析。结果 Bland-Altman分析显示:肿瘤侧与非肿瘤侧额部BIS诱导前平均偏差-0.8(-7.2~5.7);剪硬膜前平均偏差0.6(-8.3~9.5);切瘤期平均偏差1.5(-6.9~9.9);清醒后期平均偏差0.2(-9.3~9.8)。结论肿瘤侧与非肿瘤额部脑电双频指数具有良好的一致性,两者可互换。     

体素内不相干运动扩散加权成像鉴别诊断肝脏实性局灶性病变

目的探讨体素内不相干运动DWI(IVIM-DWI)对常见肝脏实性局灶性病变的鉴别诊断价值。方法回顾分析60例(61个病灶)肝内实性局灶性病变患者资料,其中肝血管瘤17个、肝细胞癌(HCC)31个、肝内胆管细胞癌(ICC)6个和肝转移瘤7个。采用IVIM-DWI测量表观扩散系数(ADC)、真实扩散系数(D)、假性扩散系数(D*)和灌注分数(f),并进行统计学分析。结果肝脏血管瘤与肝内常见恶性病变的ADC值、D值和f值差异有统计学意义(Z=-3.845、-2.727、-2.067,P均0.05),D*值差异无统计学意义(Z=-0.676,P=0.499)。ADC值诊断恶性病变的曲线下面积为0.820(P0.05),阈值1.30×10-3 mm2/s,敏感度和特异度分别为76.47%和79.55%。4种类型肝脏实性局灶性病变的ADC值和D值差异有统计学意义(χ2=18.553、8.569,P均0.05),其中肝血管瘤与HCC的ADC值差异有统计学意义(P0.001),肝血管瘤与HCC和ICC的D值差异有统计学意义(P=0.010、0.014)。结论 IVIM-DWI对常见肝脏实性局灶性病变的鉴别诊断价值有限,ADC值可能具有更高诊断效能。     

IVIM-DWI对早期活动性AS骶髂关节炎的诊断价值

[目的]探讨基于体素内不相干运动(IVIM)模型的磁共振扩散加权成像(IVIM-DWI)序列在早期活动性强直性脊柱炎(AS)中的诊断价值。[方法]收集2017年1月～2017年12月诊断的42例早期活动性强直性脊柱炎患者和40例健康志愿者的临床及影像资料。根据MRI常规序列上是否有明确骨髓水肿将活动期AS患者分为阳性组(32例)和阴性组(10例),将健康志愿者作为对照组(40例)。测量三组IVIM-DWI相关参数D_(slow)、D_(fast)、f。采用独立样本t检验分析各组IVIM-DWI参数的统计学差异,绘制ROC曲线,分析各参数对阳性组与对照组、阴性组与对照组的诊断效能。[结果] D_(slow)、D_(fast)及f的平均值分别为阳性组[(0.75±0.07)×10~(-3)mm~2/s,(10.76±0.86)×10~(-3)mm~2/s,(0.47±0.08)]、阴性组[(0.34±0.05)×10~(-3)mm~2/s,(13.02±1.50)×10~(-3)mm~2/s,(0.45±0.04)]、对照组[(0.34±0.04)×10~(-3)mm~2/s,(10.51±1.24)×10~(-3)mm~2/s,(0.38±0.03)]。阳性组的D_(slow)和f值显著高于对照组,差异有统计学意义(P0.05),而阴性组的D_(fast)和f值显著高于对照组,差异有统计学意义(P0.05)。根据ROC曲线分析得出,鉴别阳性组与对照组的最佳临界值为D_(slow)=0.51×10~(-3)mm~2/s (1.00、100%、100%)。鉴别阴性组与对照组的最佳临界值(ROC曲线下面积、敏感度及特异度)分别为D_(fast)=11.86×10~(-3)mm~2/s (0.91、90.0%、80.0%)及f=0.41(0.95、90.0%、85.0%)。[结论]当早期活动性AS患者常规序列出现明确骨髓水肿时,D_(slow)的鉴别诊断价值较高。而常规序列无明确骨髓水肿时,D_(fast)及f值的鉴别诊断价值较高。     

磁共振弥散加权成像对慢性乙型肝炎肝纤维化程度和炎症活动程度的判断价值分析

目的探讨磁共振弥散加权成像(MR-DWI)对慢性乙型肝炎肝纤维化程度和炎症活动程度的判断价值。方法选择我院自2014年1月至2016年1月我院收治的84例慢性乙型肝炎肝纤维化患者和30例未发生肝纤维化患者(对照组)为研究对象,选取同期在我院门诊体检的30例健康人为正常组。所有研究对象均经肝穿刺及病理学检查证实并接受腹部MRI平扫及DWI检查,比较各组间不同弥散敏感系数(b)值时的表观弥散系数(ADC)值的差异,分析ADC值和肝纤维化程度(分为S1、S2、S3和S4组)和肝炎活动程度(分为G1、G2、G3和G4组)之间的相关性。结果当b值为100s/mm~2、200s/mm~2和400s/mm~2时,不同肝纤维化程度组间ADC值差异均无统计学意义(均P0.05);而当b值为600s/mm~2和800s/mm~2时,S3组和S4组ADC值明显低于其他各组,差异均有统计学意义(均P0.05)。当b值为100s/mm~2和2000s/mm~2时,不同肝炎活动程度组间ADC值差异均无统计学意义(均P0.05);而当b值为400s/mm~2、600s/mm~2和800s/mm~2时,G3组和G4组ADC值明显低于其他各组,差异均有统计学意义(均P0.05)。相关性分析结果表明,当b值为600s/mm~2和800s/mm~2时,ADC值与肝纤维化程度呈现出明显的负相关(r值分别为-0.563和-0.624,均P0.05);当b值为400s/mm~2、600s/mm~2和800s/mm~2时,ADC值与肝炎活动程度呈现出明显的负相关(r值分别为-0.486、-0.586和-0.675,均P0.05)。结论磁共振弥散加权成像对于诊断慢性乙型肝炎患者肝纤维化程度具有极高的临床价值,当b值为800s/mm~2时临床价值最高,且ADC值与肝纤维化程度和炎症活动程度密切相关,是一种值得推广应用的诊疗方法。     

磁共振扩散加权成像检查对前列腺癌新辅助内分泌治疗疗效的预测价值

目的探讨磁共振扩散加权成像(DWI)检查对前列腺癌新辅助内分泌治疗疗效程度的预测价值。方法回顾性分析2016年1月至2019年9月北京大学第一医院收治的33例前列腺癌患者的病例资料。年龄平均67.7(49~81)岁。内分泌治疗前PSA平均36.8(7.5~126.5)ng/ml。33例均行前列腺MRI检查,其中30例于穿刺前平均18(2~33)d进行检查,3例于穿刺后平均35(20~44)d进行检查。扫描序列包括轴位和矢状位T1WI正反相位、冠状位T2WI压脂、轴位T1WI、轴位T2WI、轴位DWI及动态对比增强(DCE)序列。新辅助内分泌治疗前前列腺体积平均57.41(17.84~270.74)cm……3。由2名影像科医生根据前列腺影像报告和数据系统(PI-RADS)标准阅片,将PI-RADS 4~5分定义为前列腺癌灶。测量表观扩散系数(ADC)值。内分泌治疗前,患者正常外周带、移行带ADC值分别为(1.638±0.328)×10^-3mm^2/s、(1.335±0.249)×10^-3mm^2/s,癌灶ADC值为(0.828±0.291)×10^-3mm^2/s。所有患者均行经直肠超声引导下系统穿刺,病理诊断均为前列腺癌。Gleason评分:3+3分5例,3+4分4例,4+3分6例,3+5分1例,4+4分6例,4+5分8例,5+4分2例,5+5分1例。根据国际泌尿病理协会(ISUP)分级分组标准:1级(Gleason评分≤3+3=6分)5例,2级(Gleason评分3+4=7分)4例,3级(Gleason评分4+3=7分)6例,4级(Gleason评分4+4=8分、3+5=8分、5+3=8分)7例,5级(Gleason评分5+4=9分、4+5=9分、5+5=10分)11例。ISUP 1~3级为中低危组(15例),ISUP 4~5级为高危组(18例)。穿刺活检后行新辅助内分泌治疗,22例应用戈舍瑞林联合比卡鲁胺,9例应用曲普瑞林联合比卡鲁胺,2例应用亮丙瑞林联合比卡鲁胺。内分泌治疗时间平均7.2(5~13)个月。所有患者内分泌治疗后行根治性前列腺切除术。记录患者新辅助内分泌治疗后的ADC变化值和ADC变化率。比较ISUP中低危组和高危组的ADC变化值和ADC变化率,以及不同治疗反应程度患者的ADC变化值和ADC变化率。绘制受试者工作特征(ROC)曲线,分析ADC变化率预测前列腺癌新辅助内分泌治疗反应程度的价值。结果本研究33例,新辅助内分泌治疗后的前列腺体积平均28.50(6.25~113.76)cm3,与治疗前比较差异有统计学意义(Z=-4.458,P<0.05);治疗后(根治术前)PSA平均0.721(0~5.23)ng/ml,与治疗前比较差异有统计学意义(Z=-5.012,P<0.05)。治疗后ADC值分别为正常外周带(1.197±0.265)×10^-3mm^2/s(P<0.05),正常移行带(1.206±0.222)×10^-3mm^2/s(P=0.016),癌灶(1.070±0.325)×10^-3mm^2/s(P<0.05),与治疗前比较差异均有统计学意义。癌灶ADC值升高与PSA值下降无明显相关性(相关系数为0.169,P=0.382)。ISUP中低危组和高危组的ADC变化值分别为(0.315±0.173)×10^-3mm^2/s和(0.164±0.224)×10^-3mm^2/s,差异有统计学意义(P=0.047);ADC值变化率分别为(42.6±27.2)%和(23.8±29.9)%,差异无统计学意义(P=0.083)。本组33例均对内分泌治疗有反应,根治术后病理表现包括:无肿瘤细胞残留;肿瘤细胞萎缩伴空泡变性,细胞核固缩,部分产生黏液变性,部分病例可见泡沫细胞聚集;正常前列腺组织腺体萎缩,基底细胞增生。治疗明显反应组和局灶反应组的ADC变化值分别为(0.278±0.218)×10^-3mm^2/s和(0.094±0.119)×10^-3mm^2/s,差异有统计学意义(P=0.010);ADC变化率分别为(39.0±30.0)%和(11.4±17.0)%,差异有统计学意义(P=0.006)。ADC变化率预测前列腺癌新辅助内分泌治疗反应的ROC曲线下面积为0.795(P=0.02)。ADC变化率取最佳界值19.7%时,预测敏感性和特异性分别为73.9%和85.7%。结论前列腺癌患者行新辅助内分泌治疗后MRI检查的ADC值具有显著变化,且变化数值与治疗反应程度相关。DWI可以作为前列腺癌新辅助内分泌治疗效果的评估手段,并能预测治疗反应的程度。     

Value of Intravoxel Incoherent Motion for Hepatocellular Carcinoma Grading

BackgroundTo evaluate the diagnostic accuracy of intravoxel incoherent motion (IVIM) parameters in estimation of hepatocellular carcinoma (HCC) grading.Materials and methodsTwenty-nine patients with histopathologically diagnosed as 42 HCC at explant were included in this retrospective study. All patients were examined by 1.5T magnetic resonance imaging with the use of 4-channel phased array body coil. In addition to routine pre- and postcontrast sequences, IVIM (16 different b factors varying from 0 to 1300 s/mm²) and conventional diffusion-weighted imaging (3 different b factors of 50, 400, 800 s/mm²) were obtained with single-shot echo planar spin echo sequence. Apparent diffusion coefficient (ADC) and IVIM parameters including mean D (true diffusion coefficient), D* (pseudo-diffusion coefficient associated with blood flow), and f (perfusion fraction) values were calculated. Histopathologically, HCC was classified as low (grade 1, 2) and high (grade 3, 4) grade in accordance with the Edmondson-Steiner score. Quantitatively, ADC, D, D*, and f values were compared between the low- and high-grade groups by Student t test. The relationship between the parameters and histologic grade was analyzed using the Spearman’s correlation test. To evaluate the diagnostic performance of the parameters, receiver operating characteristic analysis was performed.ResultsHigh-grade HCCs had significantly lower ADC and D values than low grade groups (P = .005 and P = .026, retrospectively); ADC and D values were inversely correlated with tumor grade (r = –0.519, P = .011, r = –0.510, P = .026, respectively). High-grade HCCs had significantly higher f values when compared with the low-grade group (P = .005). The f values were positively correlated with tumor grade (r = 0.548, P = .007). The best discriminative parameter was f value. Cut-off value of 32% of f values showed sensitivity of 75.6% and a specificity of 73.5%.ConclusionADC values and IVIM parameters such as f values appear to reflect the grade of HCCs.     

Intravoxel Incoherent Motion Parameters for Assessing the Efficiency of Locoregional Bridging Treatments before Liver Transplantation

ObjectiveTo evaluate the diagnostic accuracy of Intravoxel Incoherent Motion (IVIM) parameters for assessment of tumor response after locoregional treatment (LRT) of hepatocellular carcinoma (HCC).MethodsFifteen patients with HCC who had undergone LRTs (11 transarterial radioembolization, 4 transarterial chemoembolization) were included. In addition to routine upper abdominal magnetic resonance imaging sequences, IVIM with 16 different b values and conventional diffusion weighted imaging with 3 different b factors were obtained immediately before and 8 weeks after LRTs. Magnetic resonance imaging response was evaluated according to modified Response Evaluation Criteria in Solid Tumors (mRECIST) and HCCs were categorized into 2 subgroups, responders and nonresponders. Quantitatively, the number of diffusion-changes were calculated with apparent diffusion coefficient (ADC) and IVIM parameters, including mean D (true diffusion coefficient), pseudo-diffusion coefficient associated with blood flow, and f (perfusion fraction) values. Subsequently, the pre- and post-treatment parameters were compared using the Mann-Whitney U test.ResultsConsidering all HCCs, a significant decrease was observed according to mRECIST criteria (–38.43 ± 16.49). The ADC and D values after LRTs were significantly higher than those of the preceding ones. The f values after LRTs were significantly lower than those of pre-treatment. In the responders group, ADC and D values were significantly increased and f values were significantly decreased after LRTs. No difference of statistical significance was achieved in the nonresponders group.ConclusionsADC values and IVIM parameters appear to reflect the response of LRTs as effectively as those of mRECIST. This promises new horizons in the management of pretransplant patients, especially in renal insufficiency clinical settings, owing to the elimination of contrast media administration.     

3.0T磁共振扩散加权成像诊断肾血管 平滑肌脂肪瘤

目的探讨MR扩散加权成像（DWI）及相应的表观扩散系数（ADC）对肾血管平滑肌脂肪瘤（AML）的诊断价值。方法收集经手术病理证实的肾脏AML患者15例,其中典型AML 10例,不典型AML 5例;正常对照组15名,对病变区域行DWI及常规MRI,测量b=50～1000 s/mm^2时肾脏AML及正常对照组的ADC值。结果肾脏典型AML、不典型AML及正常对照组的ADC值（×10^-3mm^2/s）分别为（0.87±0.08）、（1.55±0.34）、（1.82±0.18）,差异有统计学意义（P〈0.05）。结论3.0T磁共振DWI及ADC值测定可为诊断肾脏AML提供帮助。     

Number of Successive Cycles Necessary to Achieve Stability of Selected Ground Reaction Force Variables During Continuous Jumping

Because of inherent variability in all human cyclical movements, such as walking, running and jumping, data collected across a single cycle might be atypical and potentially unable to represent an individual’s generalized performance. The study described here was designed to determine the number of successive cycles due to continuous, repetitive countermovement jumping which a test subject should perform in a single experimental session to achieve stability of the mean of the corresponding continuously measured ground reaction force (GRF) variables. Seven vertical GRF variables (period of jumping cycle, duration of contact phase, peak force amplitude and its timing, average rate of force development, average rate of force relaxation and impulse) were extracted on the cycle-by-cycle basis from vertical jumping force time histories generated by twelve participants who were jumping in response to regular electronic metronome beats in the range 2-2.8 Hz. Stability of the selected GRF variables across successive jumping cycles was examined for three jumping rates (2, 2.4 and 2.8 Hz) using two statistical methods: intra-class correlation (ICC) analysis and segmental averaging technique (SAT). Results of the ICC analysis indicated that an average of four successive cycles (mean 4.5 ± 2.7 for 2 Hz; 3.9 ± 2.6 for 2.4 Hz; 3.3 ± 2.7 for 2.8 Hz) were necessary to achieve maximum ICC values. Except for jumping period, maximum ICC values took values from 0.592 to 0.991 and all were significantly (p ≤ 0.05) different from zero. Results of the SAT revealed that an average of ten successive cycles (mean 10.5 ± 3.5 for 2 Hz; 9.2 ± 3.8 for 2.4 Hz; 9.0 ± 3.9 for 2.8 Hz) were necessary to achieve stability of the selected parameters using criteria previously reported in the literature. Using 10 reference trials, the SAT required standard deviation criterion values of 0.49, 0.41 and 0.55 for 2 Hz, 2.4 Hz and 2.8 Hz jumping rates, respectively, in order to approximate the ICC results. The results of the study suggest that the ICC might be a less conservative but more objective method to evaluate stability of the data. Based on these considerations, it can be recommended that a force time history due to continuous, repetitive countermovement jumping should include minimum of four (the average from the ICC analysis) and possibly as many as nine successive jumping cycles (the upper limit of the ICC analysis) to establish stable mean values of the selected GRF data. This information is important for both experimental measurements and analytical studies of GRF signals due to continuous, repetitive countermovement jumping.

Key points

• The number of successive jumping cycles due to continuous, repetitive countermovement jumping obtained from a test subject during in a single testing session influences the stability of the corresponding ground reaction force variables on a cycle-by-cycle basis.
• Researchers have used different criteria and methods for determining stability of ground reaction force data for a variety of activities, making comparisons among studies and activities difficult.
• In the present study, segmental averaging technique indicated that an average of ten successive jumping cycles were necessary to achieve stability of the selected force parameters using criteria previously reported in the literature, while less conservative test-retest intra-class correlation (ICC) analysis showed that an average of four successive jumping cycles were necessary for stability.
• Based on these considerations, it can be recommended that a force time history due to continuous, repetitive countermovement jumping should include minimum of four (the average from the ICC analysis) and possibly as many as nine successive jumping cycles (the upper limit of the ICC analysis) to achieve stability of jumping force data on a cycle-by-cycle basis.
• Knowledge about the stability of jumping force data is an important to maximize reliability of their experimental and analytical characterizations.

Key words: Reliability, stability, variability, jumping, ground reaction forces     

快速千伏切换能谱CT与QCT测定羊椎体骨密度的相关性及一致性研究

目的利用羊椎体标本评价快速千伏切换能谱CT物质分离技术测定的骨松质骨密度与QCT测定的骨密度的一致性。方法新鲜羊椎体骨3副(共23个椎体),在快速千伏切换的能谱CT机上进行能谱模式扫描,利用物质分离技术获得椎体骨松质的羟基磷灰石含量(骨密度),并在同一台CT机上对每副羊骨进行标准QCT扫描,用QCT骨密度分析软件获得对应感兴趣区内的椎体骨密度。采用Pearson相关性分析、配对样本t检验、组内相关系数及Bland-Altman法进行两种方法测量结果的相关性及一致性分析。结果能谱CT物质分离技术测得的羊椎体骨密度值为(286.7±103.8) mg/cm~3,显著低于QCT测量的骨密度值(321.3±123.6) mg/cm~3,但二者高度线性相关(r=0.989,P0.001)。两种方法测量的骨密度值组内相关系数为0.974(P0.001)。对原始数据进行对数转换后应用Bland-Altman分析,差值大部分位于差值平均值±1.96标准差范围内,提示两种测量一致性好。结论能谱CT物质分离技术测定的羊椎体骨密度与QCT测定的骨密度的一致性及相关性好,有望用于临床患者骨密度的评价及随访。     

Usefulness of computed tomography based three-dimensional reconstructions to assess the critical shoulder angle

BACKGROUNDThe critical shoulder angle (CSA) is a radiographic measurement that provides an assessment of both glenoid inclination and acromial length. Higher values may correlate with the presence of rotator cuff tears. However, it is difficult to obtain a high-quality true anteroposterior (AP) radiograph of the shoulder, with any excess scapular version or flexion/extension resulting in deviation from the true CSA value. Three-dimensional (3D) bony reconstructions of computed tomography (CT) shoulder scans may be able to be rotated to obtain a similar view to that of true AP radiographs.AIMTo compare CSA measurements performed on 3D bony CT reconstructions, with those on corresponding true AP radiographs.METHODSCT shoulder scans were matched with true AP radiographs that were classified as either Suter-Henninger type A or C quality. 3D bony reconstructions were segmented from the CT scans, and rotated to replicate an ideal true AP view. Two observers performed CSA measurements using both CT and radiographic images. Measurements were repeated after a one week interval. Reliability was assessed using intraclass correlation coefficients (ICCs) and Bland-Altman plots [bias, limits of agreement (LOA)].RESULTSTwenty CT shoulder scans were matched. The mean CSA values were 32.55° (± 4.26°) with radiographs and 29.82° (± 3.49°) with the CT-based method [mean difference 2.73° (± 2.86°); P < 0.001; bias +2.73°; LOA -2.17° to +7.63°]. There was a strong correlation between the two methods (r = 0.748; P < 0.001). Intra-observer reliability was similar, but the best intra-observer values were achieved by the most experienced observer using the CT-based method [ICC: 0.983 (0.958-0.993); bias +0.03°, LOA -1.28° to +1.34°]. Inter-observer reliability was better with the CT-based method [ICC: 0.897 (0.758-0.958), bias +0.24°, LOA -2.93° to +3.41°].CONCLUSIONThe described CT-based method may be a suitable alternative for critical shoulder angle measurement, as it overcomes the difficulty in obtaining a true AP radiographic view.     

Reliability of the Ely's test for assessing rectus femoris muscle flexibility and joint range of motion

Rehabilitative protocols and orthopadic research are significantly influenced by the ability to perform reliable measures of specific physical attributes or functions. The hypothesis was that the Ely's test for evaluating rectus femoris flexibility and joint range of motion (ROM) is a reliable clinical tool. Participants (n = 54) were between the ages of 18 and 45, and had no history of trauma. Three clinicians with orthopedic expertise assessed quadriceps flexibility and joint ROM using pass/fail and goniometer scoring systems. A retest session was completed 7 to 10 days later. Statistically, Kappa values for pass/fail scoring (intrarater , interrater ) and ICC values (intrarater , interrater ) for goniometer data both indicated that the Ely's test demonstrated only moderate levels of intra‐ and interrater reliability. Measurement error values (SEM = 4°, ME = 4°, and CV = 3%) and Bland and Altman plots (with 95% Limits of Agreement) further demonstrated the degree of intrarater variance for each examiner when executing the Ely's test in a clinical setting. Results call into question the statistical reliability of the Ely's test, and provide clinicians with important information regarding the reliability limits of the Ely's test when used to clinically evaluate flexibility and joint ROM in a physically active population. More research is required to determine the variables that may confound statistical reliability of this orthopedic technique that is commonly used in a clinical setting to assess function about the thigh region. © 2008 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 26:793–799, 2008     

Flow measurements in dialysis shunts: lack of agreement between conventional Doppler, CVI-Q, and ultrasound dilution.

BACKGROUND: Measuring flow in dialysis shunts is recommended to predict imminent thrombosis. Multiple methods for measuring blood flow are in use. Numerous ultrasound protocols exist which determine volume flow using a conventional Doppler (CD) frequency shift analysis technique. All of these are subject to potentially large errors. Quantitative colour velocity index (CVI-Q) does not make use of the Doppler equation and is more precise in vitro. Ultrasound dilution (UD) measures access flow during dialysis in a non-operator-dependent way. The aim of the present study was to compare these three methods of measuring access flow in vivo for agreement with each other. METHODS: In 38 accesses flow was measured by CD, CVI-Q, and UD. All measurements were done during dialysis. Agreement was determined by intraclass correlation coefficient (ICC=R(i)) and Bland-Altman analysis. RESULTS: ICC between UD and CVI-Q was R(i)=0.56. ICC between UD and CD was R(i)=0.10, and ICC between CD and CVI-Q was R(i)=0.16. Bland-Altman analysis revealed a bias (mean difference) of -38 ml/min between UD and CVI-Q, a bias of 1129 ml/min between UD and CD, and a bias of 1167 ml/min between CVI-Q and CD. CONCLUSIONS: CD measurements did not agree with UD or CVI-Q much higher values were recorded with the former than with the latter two techniques. The agreement between UD and CVI-Q measurements is low but reasonable. Caution must be applied in comparing and interpreting values of access flow measured by different techniques.