CT和MR血管成像诊断急性肺栓塞的Meta分析

目的：应用 Meta 分析法,以 DSA 为金标准,探讨 CT 肺动脉成像（CTPA）和磁共振肺血管成像（MRPA）对肺动脉栓塞（PE）的诊断价值。方法：检索 Cochrane 图书馆、Medline 数据库、Springerlink 数据库及 Ovid 循证医学数据库中1994～2013年发表的英文文献以及知网数据库和万方医学数据库中1994～2013年发表的中文文献,按照 Cochrane 协作网推荐的诊断性实验的纳入标准,严格筛选与“CTPA 和／或 MRPA 诊断急性 PE”相关的文献。在符合条件的文献中提取诊断信息（包括真阳性值、假阳性值、真阴性值、假阴性值）和其它相关数据。采用 Stata 12软件和 Meta-disc 1．4软件对纳入文献行统计学处理,包括异质性检验,计算敏感度和特异度及其95％可信区间,选择相应的效应模型予以加权定量合并,绘制汇总的工作特征曲线（SROC）,最后进行敏感性分析。结果：按照纳入标准共获取有效文献17篇,其中与 CTPA相关的文献10篇,与 MRPA 相关的文献7篇。17篇文献均满足诊断性研究质量评价工具（QUADAS）中提出的14项标准中的10项以上。CTPA 及 MRPA 两组中的相关研究均有异质性,按照随机效应模型对纳入文献进行汇总分析。结果显示,CTPA 诊断肺栓塞的敏感度、特异度及各自的95％可信区间分别为0．78（0．74～0．82）和0．90（0．87～0．92）,MR-PA 为0．86（0．79～0．92）和0．97（0．94～0．99）,SROC 下面积分别为94％和98％。结论：CTPA 和 MRPA 对急性肺栓塞的诊断均具有很高的价值,两种方法的诊断特异度均很高,作为诊断肺栓塞的无创性检查方法可基本替代 DSA 检查。     

CT动脉造影对肺动脉栓塞诊断价值的Meta分析

目的 对以肺动脉造影为金标准，研究CT肺动脉造影(CTPA)诊断肺动脉栓塞(PE)的文献进行Meta汇总分析，评价CTPA对PE的临床诊断价值。方法 检索Cochrane图书馆、PubMed，OVID数据库和中国期刊网中的英文和中文文献，按照Cochrane协作网推荐的诊断试验的纳入标准筛选文献，并对纳入文献进行质量评估，提取纳入研究的特征信息。数据分析采用Meta-Test version0．9软件，检验异质性，并根据异质性结果选择相应的效应模型。对所有研究予以加权定量合并，计算灵敏度和特异度及其95％可信区间。绘制汇总受试者工作特征曲线(SROC)，并计算曲线下面积。最后进行敏感性分析。结果 共纳入10篇英文文献，其中7篇为A级，3篇为B级。研究对象共计855人，CTPA诊断PE的灵敏度的范围是0．57～1．00，特异度的范围是0．78～1．00。纳入研究存在异质性。按照随机效应模型计算汇总灵敏度和特异度及95％可信区间分别为0．84(0．73，0．91)和0．91(0．87，0．94)。SROC曲线下面积为94．95％。纳入文献稳定性好。结论 汇总目前关于CTPA诊断PE的研究显示，CTPA是一种灵敏度和特异度较高的无创性检查方法，还需要高质量的前瞻性研究以更准确地评价其临床价值。     

CT血管成像和MR血管成像对颅内动脉瘤诊断价值的比较

目的 采用Meta分析法比较CT血管成像（computer tomography angiography，CTA）和MR血管成像（magnetic resonance angiography，MRA）对颅内动脉瘤的诊断价值。方法 检索Cochrane图书馆、Medline、Ovid数据库和中国期刊网中有关的中英文文献，按照Cochran协作网推荐的诊断试验纳入标准选取A级文献，并提取纳入研究的诊断信息。统计分析采用Meta-Test version 0．9软件，检验异质性，再根据异质性结果选择相应的效应模犁。对所纳入的研究予以加权定量合并，计算汇总敏感度和特异度及其95％可信区间，绘制汇总受试者工作特征曲线（SROC）。结果 按照纳入标准共获取文献11篇，其中有关CTA诊断颅内动脉瘤4篇（单层螺旋CT），MRA为5篇[三维时间飞跃法（3D TOF）]，二者共同研究者2篇；前瞻性研究7篇，回顾性4篇；各组研究均存在异质性，按照随机效应模型对纳入文献行汇总分析。结果显示，对于每个颅内动脉瘤CTA诊断的敏感度、特异度及95％可信区间分别为0．84（0．78～0．88）和0．77（0．68～0．84），MRA分别为0．68（0．63～0．72）和0．76（0．70～0．82）；SROC曲线下面积分别为95．40％和79．71％。结论 对于每个颅内动脉瘤，CTA诊断的准确性明显高于3D TOF法MRA。     

MR扩散加权成像对乳腺病变良恶性鉴别的Meta分析报告

目的 采用Meta分析方法综合定量评价MR扩散加权成像(DWI)对乳腺良恶性病变的鉴别诊断价值.方法 检索Cochrane图书馆、Pubmed、Ovid循证医学数据库、Elsevier和Springer数据库及中国期刊网1997至2007年公开发表的中英文文献,按照Cochrane协作网推荐的诊断试验纳入标准筛选文献,提取纳入研究的特征信息.采用Q检验和Meta分析对纳入文献行统计学处理.结果 共纳入文献6篇,研究病灶共计479个.DWI诊断乳腺病变良恶性的敏感度范围为64.0%.92.8%,特异度范围为45.8%～96.7%.纳入文献具同质性,按照固定效应模型计算出的汇总加权敏感度和特异度及95%可信区间分别为86%(76%～92%)和80%(61%～91%);汇总受试者工作特征曲线(SROC)下面积为92.19%.敏感度分析显示纳入文献稳定性好.结论 DWI的表观扩散系数(ADC)值测量有助于乳腺病变的良恶性鉴别,但缺乏统一的扩散敏感因子(b)值和诊断阈值,其临床应用价值仍有待于前瞻性研究进一步证实.     

静脉肾盂造影和CT尿路造影对泌尿系统疾病诊断价值的比较研究

目的 评估静脉肾盂造影(IVP)和多层螺旋CT尿路造影(MSCTU)对泌尿系统疾病的诊断价值.方法 检索Cochrane图书馆、PubMed、OVID、Embase数据库1990～2008年公开发表的英文文献,以及中国期刊网1998～2008年的中文文献,按照Cochrane协作网推荐的诊断试验的纳入标准筛选文献,提取纳入研究的特征信息.对2种方法 进行异质性检验,并选择相应的效应模型对所有研究加权定量合并,计算汇总灵敏度和特异度及其95%可信区间.绘制汇总受试者工作特征曲线(SROC)并计算曲线下面积,进行敏感性分析.统计学分析采用Meta-Test和SPSS11.0软件.结果 按照纳入标准共获取文献13篇,其中有关MSCT诊断泌尿系统疾病者7篇,IVP为2篇,二者共同研究者4篇.2组研究均有异质性,但异质性均在允许范围内,按照随机效应模型对纳入文献行汇总分析.结果 显示, MSCTU与IVP扫描的汇总灵敏度和特异度及95%可信区间分别为0.95(0.93～0.96)/0.95(0.85～0.98)、0.94(0.91～0.96)/0.61(0.57～0.65);二者的SROC曲线下面积(%)分别为:98.88%和68.57%.结论 汇总分析MSCT平扫加尿路造影与IVP扫描诊断泌尿系统疾病的研究显示,前者的诊断价值明显高于后者.     

MR扩散加权成像诊断脑梗死的Meta分析

目的 评价MR扩散加权成像(DWI)诊断脑梗死的临床价值及纳入研究质量.方法 检索美国医学索引(Medline)、Ovid、Springer、Elsevier、Lippincott Williams & Wilkins(LWW)数据库及中国期刊网国内文献库(CNKI)1997年1月至2007年1月公开发表的中英文文献,按照Cochrane协作网推荐的诊断试验的纳入标准筛选文献;采用Meta分析软件对纳入文献汇总分析,获得汇总敏感度和特异度及其95%可信区间,并绘制汇总受试者工作特征(SROC)曲线、森林图和倒漏斗图.结果 按照纳入标准,共获取研究DWI诊断超急性期(发病时间≤6 h)脑梗死的文献12篇,DWI诊断超急性期脑梗死的汇总敏感度、特异度、诊断比数比及其95%可信区间分别为92%、87%和180.37,SROC曲线下面积(Az)为0.9717.敏感度分析显示去除低年资医师组诊断影响后,高年资组评价研究间异质性差异无统计学意义(Q=4.34,P>0.05),提示DWI诊断超急性期脑梗死的价值受到低年资医师判断组影响.倒漏斗图不对称提示存在发表偏倚,发表偏倚系数(Z)=10.0824.按照纳入标准,共获取研究DWI诊断超急性期和急性期(发病时间≤24 h)脑梗死文献共15篇,去除低年资医师组的诊断影响后,DWI诊断急性期脑梗死的汇总敏感度、特异度、诊断比数比及其95%可信区间分别为92%、91%和623.62,Az为0.9659.敏感度分析显示组间异质性差异无统计学意义(Q=2.70,P>0.05),提示研究人群无明显异质性.倒漏斗图不对称提示存在发表偏倚,但较超急性组减低(Z=12.6194).结论 通过Meta分析和存在的偏倚分析提示,尽管可以认为DWI作为一种无创性检查方法诊断急性和超急性脑梗死具有较高的敏感度、特异度和准确度,但是纳入文献存在偏倚.     

DWI对乳腺良恶性病变鉴别的循证诊断:Meta分析

目的:采用Meta分析方法综合定量评价DWI对乳腺良恶性病变的鉴别诊断价值。方法:检索Medline、Cochrane图书馆、中国生物医学文献数据库和中文科技期刊全文数据库等数据库中2008年1月²011年12月公开发表的中英文文献,按照Cochrane协作网推荐的诊断试验纳入标准筛选文献,提取纳入研究的特征信息。采用QUADAS条目评价纳入研究的方法学质量,采用Stata 11.0软件进行Meta分析,绘制汇总受试者工作特征曲线(summary receiver operating characteristic curve,SROC曲线),计算曲线下面积(area under curve,AUC)。结果:共纳入文献7篇,研究病灶共503个,QUADAS评价良好。DWI诊断乳腺病变良恶性的敏感度范围为58%2011年12月公开发表的中英文文献,按照Cochrane协作网推荐的诊断试验纳入标准筛选文献,提取纳入研究的特征信息。采用QUADAS条目评价纳入研究的方法学质量,采用Stata 11.0软件进行Meta分析,绘制汇总受试者工作特征曲线(summary receiver operating characteristic curve,SROC曲线),计算曲线下面积(area under curve,AUC)。结果:共纳入文献7篇,研究病灶共503个,QUADAS评价良好。DWI诊断乳腺病变良恶性的敏感度范围为58%⁹9%,特异度范围为52%99%,特异度范围为52%⁹7%。纳入文献具有同质性,按照固定效应模型计算出的汇总加权敏感度和特异度及95%可信区间分别为88%(81%97%。纳入文献具有同质性,按照固定效应模型计算出的汇总加权敏感度和特异度及95%可信区间分别为88%(81%⁹2%)、85%(78%92%)、85%(78%⁹0%);SROC曲线的AUC为0.92(0.8990%);SROC曲线的AUC为0.92(0.89⁰.94)。敏感度分析显示纳入文献稳定性好。结论:ADC值测量有助于乳腺病变的良恶性鉴别,但是良恶性ADC值范围有重叠,其实际临床应用价值有待进一步证实。     

磁共振波谱成像诊断国人前列腺癌价值的Meta分析

目的:通过Meta分析的方法评价磁共振波谱成像对国人前列腺癌的诊断价值.方法:搜集现有国内公开发表的以手术或病检结果为诊断金标准的关于评价磁共振波谱成像对国人前列腺癌诊断价值的中文文献,按照Meta分析的要求和诊断性试验公认的质量标准对所有的纳入研究进行质量评估,并提取各纳入研究的特征信息.采用STATA10.0软件检验异质性,根据异质性结果选择相应的效应模型,采用MetaDisc1.4软件计算出汇总敏感度和特异度,以诊断性试验Meta分析特有的综合受试者工作特性曲线(SROC)分析方法定性、定量地评价该诊断方法的准确度.结果:符合纳入标准的文献共10篇,汇总的诊断指标和SROC分析均显示磁共振波谱成像对国人前列腺癌的诊断具有较高的准确度,表示诊断试验准确度的指标汇总敏感度为93％(95％可信区间0.90～0.96),汇总特异度为92％(95％可信区间0.89～0.95),AUC=0.9789,Q指数=0.9351.结论:汇总目前关于磁共振波谱成像对国人前列腺癌的研究显示,磁共振波谱成像对诊断国人前列腺癌具有较高的敏感度和特异度.     

CT血管成像诊断下肢动脉硬化闭塞症的Meta分析

目的 探讨用Meta分析方法评价CTA对下肢动脉硬化闭塞症的诊断价值.方法 检索Pubmed、EBSCO、Springer、Ovid和中国期刊网(CNKI)以及Cochrane图书馆数据库,文献检索起止时间均从建库至2009年10月,同时检索纳入文献的参考文献.纳入探讨以DSA为诊断金标准的关于CTA诊断下肢动脉硬化闭塞症的文献,并逐个进行质量评价和资料提取.采用Meta Disc 1.4软件检验研究间的异质性、对诊断准确度指标进行Meta分析,绘制森林图,并进行综合受试者工作特征曲线(SROC)分析.结果 符合纳入标准的文献共24篇,各研究之间存在异质性,按照随机效应模型计算汇总敏感度、特异度与诊断优势比及其95%可信区间分别为95%(95%可信区间:94%～95%)、96%(95%可信区间:95%～96%)、471.13(95%可信区间:242.92～913.71).SROC下面积为为0.9888,Q指数为0.9555.亚组分析显示:CT层数所致诊断准确度之间的差异有统计学意义(P＜0.05).结论 对于下肢动脉硬化闭塞症患者,CTA是一项切实可行的影像检查方式,拥有较高的敏感度及特异度.然而对于下肢严重缺血的患者,尚需慎重对待CTA检查结果.     

动态增强CT净增值鉴别孤立性肺结节的价值评价

目的:应用Meta分析方法对动态增强CT扫描中以净增CT值鉴别诊断孤立性肺结节(SPNs)良恶性的价值进行评价。方法:检索Cochrane图书馆,PUBMED/MEDLINE、EMBASE、OVID、SPRINGLINK数据库(1990年1月~2006年12月)以及中国期刊网(CNKI,1994年1月~2006年12月)的英文和中文文献,筛选出与动态增强CT扫描SPNs有关的文献。采用Meta-Test 0.9软件对数据进行分析,计算汇总灵敏度、特异度及其95%可信区间,绘制出汇总受试者工作特征曲线(SROC),计算曲线下面积,评价动态增强CT扫描对SPNs的诊断价值。结果:按照制定标准共筛选出文献13篇。以动态增强扫描后SPNs净增CT值≥15HU诊断为恶性的汇总灵敏度、特异度及95%可信区间为0.96(0.93-0.98),0.56(0.50-0.62);SPNs净增CT值≥20HU诊断为恶性的汇总灵敏度、特异度及95%可信区间为0.95(0.90-0.98),0.65(0.56-0.74);两者的SROC曲线下面积分别为:0.9587,0.9584。结论:以动态增强扫描净增CT值方法对恶性SPNs诊断价值很高。以15HU和20HU分别作为诊断阈值时,两者诊断价值无明显差异(P=0.9964)。     

右房密度监测触发 CT 肺动脉成像

目的：通过对右房(RA)CT 值的监测,寻找其达峰时间,优化 CT 肺动脉成像(CTPA)显像。方法采集拟行 CTPA 的患者60例,随机分成2组,肺动脉触发(PT)组(n=30)：注射70 mL 对比剂(CA)并屏气,采用肺动脉干 CT 值监测触发方式获取CTPA 图像;RA 组(n=30)：注射40 mLCA,自由呼吸,并采用 RA 监测触发方式。对图像质量、肺动脉及肺静脉 CT 值、肺动脉-肺静脉密度差值等进行对比。结果RA 组图像质量、肺动脉平均值及肺动脉-肺静脉密度差明显高于 PT 组(P <0.05),而 RA 组肺静脉 CT 值更低(P <0.05)。肺动脉6级分支显示比例2组无统计学差异(P >0.05)。结论自由呼吸状态下基于 RA 密度监测触发的 CTPA 能在肺静脉 CT 值最低时使肺动脉得到最大强化,且 CA 使用量减少。     

NO吸入降低高原肺水肿患者肺动脉高压的动态观察

目的 了解NO吸入对高原肺水肿的治疗作用及突然停止吸入NO引起的肺动脉压反跳作用。方法 采用右心漂浮导管检测法，观察了7例高原肺水肿患者吸入NO及突然停止吸入NO后血流动力学及动脉血气等指标的变化，同时采用Lake评分法对患者的病情进行定量评估。结果 吸入NO 5min后，高原肺水肿患者的肺循环阻力、肺动脉平均压明显下降，血氧分压明显升高，而对心事、体动脉压平均值、心输出量等指标无明显影响；高原肺水肿患者在突然停止吸入NO而改吸室内空气后，下降的肺动脉压迅速反弹，5min后肺动脉压已明显高于吸入NO前水平，10min后肺动脉压反跳达最高值，与此同时，患者的血氧分压明显下降，病情定量分数已显著高于吸入NO前水平。结论 吸入NO对高原肺水肿患者肺动脉高压有选择性降低作用，对体循环压无明显影响，吸入NO的高原肺水肿患者，在短时间吸NO突然撤离后，存在着肺动脉压反跳性的异常升高及血流动力学不稳等现象。     

Computed tomographic pulmonary angiography in the assessment of severity of chronic thromboembolic pulmonary hypertension and right ventricular dysfunction

Purpose

The aim was to investigate the role of computed tomographic pulmonary angiography (CTPA) in the assessment of severity and right ventricular function in chronic thromboembolic pulmonary hypertension (CTEPH).

Materials and methods

Clinical and radiological data of 56 patients with CTEPH January 2006–October 2009 were retrospectively reviewed in the present study. All patients received CTPA with a 64-row CT using the retrospective ECG-Gated mode before digital subtraction pulmonary angiography and right-heart catheterization. CTPA findings including Right Ventricular diameter (RVd) and left ventricular diameter (LVd) were measured at the end diastole. CT Pulmonary Artery Obstruction Indexes including Qanadli Index and Mastora Index were used in the assessment of severity of pulmonary arterial obstruction. Hemodynamic parameters and pulmonary hypertension classification were evaluated by right-heart catheterization in all patients. Right ventricular function was measured with echocardiography in 49 patients.

Results

Qanadli Index and Mastora Index respectively were (37.93 ± 14.74)% and (30.92 ± 16.91)%, which showed a significant difference (Z = −5.983, P = 0.000) and a good correlation (r = 0.881, P = 0.000). Neither Qanadli nor Mastora Index correlated with pulmonary hypertension classification (r = −0.009, P = 0.920) or New York Heart Association heart function classification (r = −0.031, P = 0.756). Neither Qanadli nor Mastora Index correlated with any echocardiographic right ventricular parameters (P > 0.05), while RVd/LVd by CTPA correlated with echocardiographic right ventricular functional parameters (P < 0.05). Both Qanadli (r = −0.288, P = 0.006) and Mastora Index (r = −0.203, P = 0.032) demonstrated a weakly negative correlation with SPO₂. CTPA findings correlated with hemodynamic variables. Backward linear regression analysis revealed that the RVd/LVd, Right Ventricular Anterior Wall Thickness (RVAWT), Main Pulmonary Artery trunk diameter (MPAd) were shown to be independently associated with mean Pulmonary Artery Pressure (mPAP) levels (model: r² = 0.351, P = 0.025; RVd/LVd: beta = 11.812, P = 0.000; RVAWT: beta = 2.426, P = 0.000; MPAd: beta = 0.677, P = 0.003).

Conclusion

Computed tomographic pulmonary angiography is a valuable tool to evaluate hemodynamics, right ventricular function of CTEPH, but neither Qanadli Index nor Mastora Index can reflect pulmonary arterial obstruction in CTEPH accurately.     

Energy efficiency and pulmonary artery flow after balloon pulmonary angioplasty for inoperable,chronic thromboembolic pulmonary hypertension: Analysis by phase-contrast MRI

PurposeThe aims of this study were to propose a new quantitative method for pulmonary artery (PA) flow energetics using phase-contrast magnetic resonance imaging (PC-MRI), and to investigate how balloon pulmonary angioplasty (BPA) impacts energetics in chronic thromboembolic pulmonary hypertension (CTEPH).Materials and methodsPC-MRI at 3-Teslar and with a flow sensitive gradient echo was used to examine energetics prior to and following BPA for 24 CTEPH patients. Stroke volume (m; ml) and mean velocity (V; mm/s) for the main pulmonary artery (PA), right PA, and left PA were calculated from a time-flow curve derived from PC-MRI. Based on the Bernoulli principle, PA energy was identified as 1/2 mV² (μj/kg), and energy loss was defined as the following equation “energy loss = main PA energy − (rt. PA energy + lt. PA energy)”.ResultsRight PA energy was significantly greater post-BPA than pre-BPA (61 ± 55 vs. 32 ± 40 μj/kg). There was no difference in main PA and left PA energies. Energy loss was significantly decreased post-BPA (18 ± 97 μj/kg) than pre-BPA (79 ± 125 μj/kg). An optimal cutoff of left PA energy of 45 μj/kg pre-BPA can be used to predict patients with mPAP ≥ 30 mmHg after BPA, with an area under the curve of 0.91, 78% sensitivity, and 92% specificity.ConclusionAnalysis of PA energetics using phase-contrast MRI demonstrates that BPA improves energy loss in CTEPH. In addition, BPA responses can be predicted by PA energy status pre-treatment.     

CT pulmonary angiography is the first-line imaging test for acute pulmonary embolism: a survey of US clinicians

RATIONALE AND OBJECTIVES: Our aim is to document current imaging practices for diagnosing acute pulmonary embolism (PE) among physicians practicing in the United States and explore factors associated with these practices. MATERIALS AND METHODS: Between September 2004 and February 2005, we surveyed by mail 855 physicians selected at random from membership lists of three professional organizations. Physicians reported their imaging practices and experiences in managing patients with suspected acute PE during the preceding 12 months. RESULTS: Completed questionnaires were received from 240 of 806 eligible participants (29.8%) practicing in 44 states: 86.7% of respondents believed that computed tomographic pulmonary angiography (CTPA) was the most useful imaging procedure for patients with acute PE compared with 8.3% for ventilation-perfusion (V-P) scintigraphy and 2.5% for conventional pulminary angiography (PA). After chest radiography, CTPA was the first imaging test requested 71.4% of the time compared with V-P scintigraphy (19.7%) and lower-limb venous ultrasound (5.8%). Participants received indeterminate or inconclusive results 46.4% of the time for V-P scintigraphy, 10.6% of the time for CTPA, and 2.2% of the time for PA. CTPA was available around the clock to 88.3% of participants compared with 53.8% for V-P scintigraphy and 42.5% for PA. A total of 68.6% of respondents received CTPA results in 2 hours or less (vs 37.5% for V-P scintigraphy and 22.9% for PA). CTPA also provided an alternative diagnosis to PE or showed other significant abnormalities 28.5% of the time, and these findings frequently altered management. CONCLUSION: US clinicians unequivocally prefer CTPA in patients with suspected acute PE. Reasons for this preference include availability and timely reporting, a lower rate of inconclusive results, and the additional diagnostic capabilities that CTPA can provide.     

Combined helical computed tomographic pulmonary angiography and lung perfusion scintigraphy for investigating acute pulmonary embolism.

AIM: To evaluate a diagnostic protocol incorporating helical computed tomographic pulmonary angiography (CTPA) and lung perfusion scintigraphy in the detection or exclusion of pulmonary embolism (PE) in routine clinical practice. MATERIALS AND METHODS: A prospective observational study of 808 consecutive patients with suspected acute PE was undertaken over a 23-month period. Twenty-nine cases who failed to follow the protocol were excluded, leaving 779 cases to be reviewed. The three main outcome measures were negative perfusion scintigraphy, positive CTPA and other significant abnormalities demonstrated on CT. RESULTS: Two hundred and thirty-one (30%) had negative perfusion scintigraphy and no further investigation. CTPA was performed in 548 (70%) and PE confirmed in 193 (25% of all patients). Other significant abnormalities were demonstrated in 25 (3%). CTPA was technically inadequate in 15 (2%). CONCLUSIONS: A confident conclusion was achieved in 449 cases (58%), with PE excluded in 231 (30%), proved in 193 (25%), and relevant alternative abnormalities found in 25 (3%). This protocol using both perfusion scintigraphy and CTPA is practical and more effective than either investigation alone.     

The use of a D-dimer assay in patients undergoing CT pulmonary angiography for suspected pulmonary embolus.

PURPOSE: To assess the ability of a semi-quantitative latex agglutination D-dimer test Accuclot with bedside measurements of arterial oxygen saturation, respiratory and cardiac rates to exclude pulmonary embolism (PE) on computed tomographic pulmonary angiography (CTPA). MATERIALS AND METHODS: All patients referred to our CT unit for investigation of suspected acute pulmonary embolism were enrolled. Pulse oximetery, respiratory rate, heart rate and blood sampling for D-dimer testing were carried out just before CT. A high resolution CT (HRCT) of the chest was followed by a CT pulmonary angiogram (CTPA). The images were independently interpreted at a workstation with cine-paging and 2D reformation facilities by three consultant radiologists blinded to the clinical and laboratory data. If positive, the level of the most proximal embolus was recorded. Discordant imaging results were re-read collectively and consensus achieved. RESULTS: A total of 101 patients were enrolled. The CTPA was positive for PE in 28/101 (28%). The D-dimer was positive in 65/101 (65%). Twenty-six patients had a positive CT and positive D-dimer, two a positive CT but negative D-dimer, 39 a negative CT and positive D-dimer, and 34 a negative CT and negative D-dimer. The negative predictive value of the Accuclot D-dimer test for excluding a pulmonary embolus on spiral CT was 0.94. Combining the D-dimer result with pulse oximetry (normal SaO2 > or = 90%) improved the negative predictive value to 0.97. CONCLUSION: A negative Accuclot D-dimer assay proved highly predictive for a negative CT pulmonary angiogram in suspected acute pulmonary embolus. If this D-dimer assay were included in the diagnostic algorithm of these patients a negative D-dimer would have unnecessary CTPA rendered in 36% of patients.