肺灌注显像结合X线胸片诊断急性肺栓塞

目的探讨肺灌注显像／x线胸片检查（Q／X）替代肺灌注／通气显像（Q／V）用于急性肺栓塞诊断的可行性。方法72例疑诊急性肺栓塞，且肺灌注显像显示至少有一个肺段灌注缺损的患者，24h内行x线胸片检查和肺通气显像，比较Q／X和QIV的诊断符合率和准确性。结果Q／x与Q／V结果的符合率为84．7％，Q／x对Q／V的阳性预测值为83．7％，阴性预测值为87．0％。在该组病例中，Q／X诊断急性肺栓塞的灵敏度为94．9％，特异性为63．6％，准确性为80．6％；而Q／V则分别为94．9％，78．8％和87．5％。5例慢性阻塞性肺部疾病（COPD）Q／X均显示不匹配，而Q／v均显示匹配，两者结果不同。结论对于多数疑诊急性肺栓塞患者，Q／X可以替代Q／v用于诊断，但对于COPD患者应选择Q／V。     

核素肺通气/灌注显像在肺动脉血栓栓塞症中的应用

目的 应用肺通气／灌注（V／Q）显像研究下肢深静脉血栓（DVT）患者肺栓塞（PE）发病情况，并与CT血管造影（CTA）或MR血管造影（MRA）结果进行比较。方法 85例DVT患者进行肺通气（Technegas）／^99Tc^m-聚合白蛋白（MAA）灌注显像和X线胸片检查，其中13例同期进行肺CTA或MRA检查。根据PIOPED诊断标准（1995年修正版），综合分析肺V／Q显像和X线胸片结果，划分为PE高、中、低、极低度可能性和正常5类，并以低、中和高度PE可能性者为阳性，极低可能性和正常者为阴性。结果 85例患者中，PE高度可能性34.1％，中度可能性8．2％，低度可能性7．1％，极低度可能性1．2％，正常49．4％，共计阳性率49．4％，阴性率50．6％。13例同期进行CTA或MRA检查的患者中，3例V／Q显像和CTA或MRA发现病灶数量和范围一致，10例不一致。肺动脉部分栓塞时，由于血流可通过，肺组织灌注可能正常，V／Q显像往往不能发现病变血管。而外周肺段、亚分段较小肺动脉栓塞时，CTA或MRA容易漏诊。结论 V／Q显像可以提供优良、准确的PE诊断结果，CTA检查与其可优势互补。     

肺灌注/通气显像与肺动脉造影诊断肺栓塞的对比分析

目的：评价肺灌注／通气显像诊断肿栓塞的价值。方法：回顾性分析45例疑肺栓塞患者的肺核素显像结果，并与肺动脉造影检查对照。结果：肺动脉造影诊断为肺栓塞的患者26例，有180个肺动脉支为充盈缺损，其肺灌注显像示167个节段呈完全肺段性或亚肺段缺损，符合率为92．7％。肺动脉造影显示为86个肺动脉支为部分充盈缺损，肺灌注显像有63个肺段或亚肺段缺损，符合率为73．2％（P＜0．01）。肺核素显像对肺栓塞诊断的灵敏度为92．3％，特异性为84．2％，阳性预测值和阴性预测值均为88．9％。26例肺动脉造影诊断为肺栓塞的患者，有23例行肺通气显像，通气／灌注均不匹配。结论：肺灌注／通气显像对肺栓塞诊断具有重要的临床价值。     

肺通气血流灌注显像、螺旋CT肺动脉造影及D-二聚体测定对诊断肺栓塞的临床价值

目的探讨放射性核素肺通气血流灌注比值(V/Q)显像和螺旋CT肺动脉造影(SCTPA)以及血浆D-二聚体(dimer)检测对肺栓塞(PE)诊断的临床价值。方法对我院2010年2月—2013年2月可疑肺栓塞的患者,行V/Q显像、SCTPA检查和血浆D-二聚体测定以及相关检查,以最终临床诊断为依据,分别评价V/Q显像、SCTPA和血浆D-二聚体测定对PE的诊断价值。结果 278例高度怀疑PE患者经上述检查确诊PE患者151例,V/Q显像、SCTPA检查和血浆D-二聚体测定诊断PE的灵敏度、特异性、阳性预测值、阴性预测值分别为93.6%(132/141)、96.0%(120/125)、96.4%(132/137)、93.0%(120/129);95.8%(137/143)、96.9%(124/128)、97.2%(137/141)、95.4%(124/130);99.3%(140/141)、43.1%(59/137)、64.2%(140/218)、98.3%(59/60)。结论血浆D-二聚体测定的价值主要用于排除PE。对PE患者的检查应力求全面,V/Q显像、SCTPA检查均有其优点和不足,只有全面掌握各项检查的特点,才能对该项检查对疾病的诊断价值做出正确评价,从而正确运用这一诊断方法更好地服务于临床。     

放射性核素肺显像与螺旋CT诊断急性肺栓塞的对比研究

目的 比较肺通气／灌注（V／Q）显像与多层螺旋CT肺动脉造影（CTPA）在诊断急性肺动脉血栓栓塞症（PTE）方面的临床价值。方法 前瞻性分析2005年10月～2006年5月共51例临床疑诊急性PTE患者的肺灌注显像，其中18例行肺通气显像，并与CTPA对比。以汇总所有临床资料、各实验室检查及影像学检查后讨论得出的最终诊断作为“标准”。结果 最终24位患者被诊断为PTE占47．1％（24／51例），V／Q显像与CTPA的灵敏度分别为95．8％（23／24例）和95．8％（23／24例），特异性分别为88．9％（24／27例）和92．6％（25／27例），准确性分别为92．2％（47／51例）和94．1％（48／51例）。在定性诊断方面，2种影像学检查结果差异无统计学意义（χ^2=0．14，P=0．71），两者定性诊断符合率为86．3％（44／51例），Kappa值为0．73。24例PTE患者中，CTPA显示为“完全阻塞”的肺动脉血管所对应的44个肺段中，肺灌注显像显示为“放射性稀疏、缺损”的肺段数为32个（72．7％）；CTPA显示为“部分充盈缺损”的肺动脉血管所对应的266个肺段中，肺灌注显像显示为“放射性稀疏、缺损”的肺段数为155个（58．3％），显示为“亚肺段放射性稀疏、缺损”的肺段数为9个（3．4％）。结论 V／Q显像与CTPA在PTE定性诊断方面符合率高，一致性好，但在定位方面存在差异；两者为互补关系。     

肺通气/灌注显像在慢性血栓栓塞性肺动脉高压诊断中的临床价值

目的 探讨肺通气/灌注(V/Q)显像在慢性血栓栓塞性肺动脉高压(CTEPH)诊断中的临床价值.方法 回顾性分析临床怀疑CTEPH的76例患者(男46例,女30例,年龄27～84岁)的肺V/Q断层显像结果,与CT肺动脉造影(CTPA)检查结果进行比较.分别计算核素显像与CTPA诊断CTEPH的灵敏度、特异性、准确性、阳性预测值和阴性预测值,并应用SPSS 11.5软件行x2检验,对2种方法诊断效能进行比较.同时对CTEPH患者V/Q显像受累肺段的分布进行分析.结果 临床最终确诊CTEPH 47例(肺动脉造影或病史结合影像学检查结果确诊),非CTEPH 29例.V/Q显像对CTEPH的诊断灵敏度、特异性、准确性、阳性预测值和阴性预测值分别为97.9％(46/47)、86.2％ (25/29)、93.4％(71/76)、92.0％(46/50)和96.2％ (25/26),CTPA的检查对应结果分别为78.7％ (37/47)、93.1％ (27/29)、84.2％ (64/76)、94.9％ (37/39)和73.0％(27/37),V/Q显像的灵敏度(x2=5.818,P=0.012)和阴性预测值(x2=5.693,P=0.017)均高于CTPA.V/Q显像可以对CTEPH和特发性PAH及遗传性PAH进行鉴别诊断:CTEPH患者灌注显像呈肺叶、肺段分布的稀疏缺损区,而通气显像基本正常,特发性及遗传性PAH灌注显像则表现为不呈肺段分布的多发、散在的“斑片状”稀疏缺损区或血流灌注基本正常.在47例CTEPH患者的940个肺段中,肺灌注断层显像共检出585个(62.2％)受累肺段,平均每例患者有12.4个肺段受累,右肺受累比例明显高于左肺[36.2％ (340/940)与26.1％ (245/940);x2=40.85,P＜0.01].结论 V/Q显像在CTEPH的诊断和鉴别诊断中具有较高的临床应用价值.V/Q显像正常可排除CTEPH的诊断;而在临床高度怀疑CTEPH、CTPA与肺动脉造影检查均为阴性时,V/Q显像对CTEPH的诊断具有重要意义.     

肺通气/灌注显像对急性肺血栓栓塞症患者的诊断价值

目的 评价放射性核素肺通气／灌注（V／Q）显像在急性肺血栓栓塞症（PTE）诊断中的价值及国人肺动脉血栓栓塞后肺血流灌注受损情况和受累肺段、肺叶的分布特点。方法 采用前瞻性描述性研究方法，将明确诊断为PTE的519例患者分为大面积、次大面积PTE组（249例）和非大面积（不含次大面积）PTE组（270例）。对519例急性PTE患者均进行了肺V／Q显像，其中有773例次与CT肺动脉造影（CTPA）结果进行了对比分析。结果 在治疗前行肺V／Q显像和CTPA的PTE患者中，PTE的总检出率分别为93．3％和89．3％（P〉0．05）；急性大面积和次大面积PTE组的检出率分别为86．9％和100％（P〈0．001）；急性非大面积PTE组的检出率分别为98．2％和77．5％（P〈0．001）。肺V／Q显像示病变分布的特点为：右肺多于左肺，下叶多于上叶，背段多于前段。肺V／Q显像与CTPA的符合率比较：肺高于肺叶，肺叶高于肺段，溶栓组高于抗凝组。结论 肺V／Q显像在急性PTE的诊断中具有重要的作用和独特的价值，与CTPA联合应用，可起到决定性的诊断作用。PTE患者肺内血栓的分布特点符合“浓度守衡定律”。     

ROC曲线评价18F—FDGPET／CT、99Tcm—MDP骨显像及二者联合对骨转移的检出效能

目的采用ROC曲线比较18F-FDGPET／CT、99TcmMDP骨显像及二者联合对骨转移患者的检出效能。方法296例恶性肿瘤患者在2个月内同时接受了18F-FDGPET／CT和99TcmMDP骨显像,对2种显像结果按5分法（0分：骨转移阴性,1分：可能阴性,2分：不能确定,3分：可能阳性,4分：肯定阳性）分别评分,两者之和为联合评分值。以病理诊断或临床随访为确诊“金标准”,采用。检验比较ROC曲线下面积,以评价骨显像、PET／CT及联合评分法对骨转移患者的检出效能,采用r检验比较不同方法在各自最佳诊断阈值下的灵敏度、特异性、准确性、阳性预测值、阴性预测值。结果296例患者中,确诊骨转移阳性61例（占20．6％）、阴性235例（占79．4％）。骨显像、PET／CT及联合评分诊断骨转移的ROC曲线下面积（95％可信区间）分别为0．919（0．867—0．971）、0．949（0．906～0．991）、0．994（0．988～0．999）,联合评分法的曲线下面积明显大于骨显像（z=2．866,P=0．004）和PET／CT（z=2．027,P=0．043）各自单独评分法,骨显像和PET／CT法曲线下面积差异没有统计学意义（z=0．881,P=0．378）。最佳阈值点下,骨显像和PET／CT单独检出骨转移患者的灵敏度、特异性、准确性、阳性预测值、阴性预测值分别为90．2％（55／61）、85．1％（200／235）、86．1％（255／296）、61．1％（55／90）、97．1％（200／206）和88．5％（54／61）、97．0％（228／235）、95．3％（282／296）、88．5％（54／61）、97．0％（228／235）,而联合评分检出的结果分别为98．4％（60／61）、95．7％（225／235）、96．3％（285／296）、85．7％（60／70）、99．6％（225／226）。PET／CT对骨转移患者检出的特异性（X2=19．600,P〈0．001）、准确性（X2=13．755,P〈0．001）、阳性预测值（x2=13．608,P〈0．001）均高于骨显像,灵敏度（r=0,P=1．000）差异无统计学意义;与骨显像、PET／CT单独评分比较,联合评分法检出的特异性（X2=19．862,P〈0．001）、准确性（x2=23．361,P〈0．001）和阳性预测值（x2=11．791,P=0．001）均明显高于骨显像,灵敏度明显高于PET／CT（x2=4．167,P=0．031）。结论18F—FDGPET／CT对骨转移患者的检出效能优于99Tcm—MDP骨显像,二者联合明显提高了对骨转移患者的检出率。     

^99Tc^m—MIBISPECT结合定位CT显像诊断功能亢进异位甲状旁腺的价值

目的评价^99Tc^m-甲氧基异丁基异腈（MIBI）SPECT结合定位CT显像对功能亢进异位甲状旁腺的定位诊断价值。方法回顾性分析28例功能亢进异位甲状旁腺患者的手术、病理及影像资料。28例均行常规CT检查,其中25例先行双时相^99Tc^m-MIBI显像,对甲状腺外存在异常放射性浓聚灶患者,随即进行SPECT结合定位CT采集,经计算机处理得到二者融合图像,对放射性浓聚灶进行精确定位。以手术及病理检查结果为检查“金标准”,所有患者均按4个甲状旁腺计算,经手术及病理检查证实的为阳性,其余判为阴性。CT检查与核医学显像结果的比较采用四格表,检验。结果手术中28例患者共摘除28个异位病灶,均为单发。病理检查结果均为腺瘤。28例患者常规CT检查共发现22个阳性病灶,其中真阳性17个,假阳性5个,另假阴性11个,真阴性79个;25例^99Tc^m-MIBISPECT结合定位CT显像发现阳性病灶23个,无假阳性,另假阴性2个,真阴性75个。常规CT检查与核医学显像对检出病理性甲状旁腺的灵敏度分别为61％（17／28）、92％（23／25）,特异性为94％（79／84）、100％（75／75）,准确性为86％（96／112）、98％（98／100）,阳性预测值为77％（17／22）、100％（23／23）,阴性预测值为88％（79／90）、97％（75／77）;两者间比较差异有统计学意义,灵敏度：χ^2=6．98,P〈0．01,特异性：χ^2=4．61,P〈0．05,准确性：χ^2=10．30,P〈0．01,阳性预测值：χ^2=5．88,P〈0．05,阴性预测值：χ^2=5．36,P〈0．05。结论^99Tc^m—MIBI SPECT结合定位CT显像对功能亢进异位甲状旁腺的定位诊断优于常规CT,但存在一定的假阴性。     

肺通气/灌注显像对肺栓塞疗效的评价

目的 探讨肺通气／灌注（V／Q）显像在观察肺栓塞（PE）溶栓和抗凝治疗效果中的价值。方法 对65例抗凝和溶栓治疗的PE患者，治疗前后分别给予^99Tc^m气体37-74MBq和^99Tc^m-聚合白蛋白（MAA）148—185MBq后行8个体位V／Q显像；并在治疗后不同时间多次重复V／Q显像。结 果44例PE患者296个受损肺段，单纯抗凝治疗1年半内，V／Q显像显示106个肺段恢复正常（35．8％），69个受损肺段改善（23．3％），121个肺段无改善（40．9％）。21例PE患者165个受损肺段，溶栓结合抗凝治疗后V／Q显像示有85个肺段恢复正常（51．5％），有29个肺段改善（17．6％），有51个肺段无改善（30．9％）。其中在PE发病7d内治疗效果最佳，单纯抗凝治疗7d与14d疗效之间比较及溶栓结合抗凝治疗7d与14d疗效之间比较，差异均有统计学意义（χ^2=8．79和56．31，P〈0．05和〈0．01）。结论 V／Q显像能较好地评价PE抗凝和溶栓治疗效果。     

Can plasma D-dimer predict the result of a ventilation–perfusion scan?

The use of plasma D-dimer assay has been advocated for the exclusion of pulmonary embolism. We retrospectively looked at 840 patients in whom both ventilation–perfusion scan and D-dimer assay were performed within 48 h. The negative predictive value of a negative D-dimer assay was 96% for emergency admissions and 98% for inpatients. We present the cases of two patients with negative D-dimer assay results who had a high-probability lung scan, and we have found a further three patients with negative D-dimer assay results who had an intermediate-probability lung scan.     

彩色多普勒超声联合D-二聚体对周围型下肢深静脉血栓筛查的价值

目的探讨彩色多普勒超声(CDUL)联合D-二聚体检测对周围型下肢深静脉血栓的筛查价值。方法对1821例下肢深静脉血栓的高危患者行下肢深静脉CDUL检查及D-二聚体的检测。分别计算CDUL、血浆D-二聚体浓度水平检测以及二者联合对高危人群中周围型下肢深静脉血栓形成的灵敏度、特异度、阳性预测值、阴性预测值以及Kappa值。结果CDUL诊断周围型下肢深静脉血栓形成的灵敏度、特异度、阳性预测值、阴性预测值、Kappa值为95.8%、94.5%、88.2%、98.1%、0.881。血浆D-二聚体浓度检测诊断周围型下肢深静脉血栓形成的灵敏度、特异度、阳性预测值、阴性预测值、Kappa值为85.2%、95.6%、89.3%、93.8%、0.818。二者联合诊断周围型下肢深静脉血栓形成的灵敏度、特异度、阳性预测值、阴性预测值、Kappa值为98.0%、100.0%、100.0%、99.1%、0.986。CDUL联合D-二聚体检测与单独行D-二聚体检测及CDUL检查的差异均有统计学意义(均P<0.05)。结论CDUL检查联合血清D-二聚体检测对筛查周围型下肢深静脉血栓有较高的诊断准确率,具有较高的临床价值。     

Role of a quantitative D-dimer assay in determining the need for CT angiography of acute pulmonary embolism

OBJECTIVE: Our goal was to use the results of a quantitative D-dimer assay to determine the need for pulmonary CT angiography in patients suspected of having acute pulmonary embolism. MATERIALS AND METHODS: From July 2001 to December 2002, 755 patients underwent pulmonary CT angiography for the evaluation of acute pulmonary embolism. A rapid, fully automated quantitative D-dimer assay was obtained in more than half the patients. The electronic medical records of the patients were subsequently reviewed to analyze the negative predictive value of the D-dimer assay in the diagnostic workup of acute pulmonary embolism and to determine the outcome of the patients who had negative findings on both D-dimer assay and pulmonary CT angiography at 3-month follow-up. RESULTS: Of the 755 patients who underwent pulmonary CT angiography, 666 (88.2%) had negative findings, 73 (9.7%) had positive findings, and 16 (2.1%) were indeterminate. A total of 426 patients underwent both pulmonary CT angiography and D-dimer level evaluation, and 84 of these had negative findings (< 0.4 microg/mL) on D-dimer assay. Eighty-two of the 84 patients with negative findings on D-dimer assay had negative findings on pulmonary CT angiography; two were indeterminate and both subsequently had low-probability ventilation-perfusion studies. Among patients with positive D-dimer assays, no one with a level between 0.4 and 1.0 microg/mL had pulmonary CT angiography with findings positive for pulmonary embolism. CONCLUSION: A quantitative D-dimer assay was effective in excluding the need for pulmonary CT angiography and had high negative predictive value when the D-dimer level was less than 1.0 microg/mL.     

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.     

D-dimer assay for deep vein thrombosis: its role with colour Doppler sonography

AIM: To evaluate the role of a negative D-dimer assay in the initial management of patients with clinically suspected deep venous thrombosis (DVT), using colour Doppler ultrasound as the primary diagnostic technique. MATERIALS AND METHODS: A double-blind prospective trial was performed on 143 patients with clinically suspected DVT. All patients underwent a D-dimer assay prior to anticoagulant therapy. DVT was confirmed or excluded by diagnostic colour Doppler ultrasound within 24 h of presentation. RESULTS: In nearly one-third of the cases (31.8%), Doppler ultrasound was positive. The D-dimer assay demonstrated a sensitivity of 97.7% with only one false-negative, but the specificity was low at 48.9% with 45 false-positive results. The positive predictive value for D-dimer assay was 48.8%, whilst the important negative predictive value was 98%. CONCLUSION: If D-dimer was used to screen for DVT, and patients with negative results were not imaged, then the imaging workload could be reduced by 35%. In this study one small calf vein thrombus would have been missed by adopting this practice.Bradley, M. (2000). Clinical Radiology 55, 525-527.     

肺通气/灌注显像结合血浆D-二聚体分析对肺栓塞的诊断价值

目的　探讨肺通气 灌注 (V Q)显像结合血浆D 二聚体 (dimer)分析在肺栓塞 (PE)诊断中的临床价值。方法　疑有PE的患者 10 4例进行肺V Q显像和血浆D dimer分析。以临床诊断为依据 ,分别评价肺V Q显像、D dimer分析及V Q显像结合D dimer分析对PE的诊断价值。结果　 4 4例确诊为PE ,6 0例排除PE。肺V Q显像对 86例 (82 .7% )明确诊断 ,另 18例 (17. 3% )为非确定性诊断。V Q显像诊断PE的灵敏度、特异性和准确性分别为 84. 1%、75 .0 %和 78. 8%。血浆D dimer分析诊断PE的灵敏度、特异性和准确性分别为 93. 2 %、6 0 . 0 %和 74 . 0 %。以D dimer <5 0 .0mg L作为V Q显像中非确定性诊断病例排除PE的依据 ,则诊断的特异性和准确性分别提高到 85. 0 %和 84 . 6 %。结论　在V Q显像中出现非确定性诊断结果时 ,血浆D dimer测定可作为排除PE的依据 ;V Q显像结合血浆D dimer测定可提高诊断的特异性和准确性。     

Complementarity of lung scintigraphy and D-dimer test in pulmonary embolism

D-dimer assay (DDA), measuring fibrin degradation products, was compared with lung scintigraphy (LS) in a prospective unselected series of 83 consecutive patients referred owing to suspicion of pulmonary embolism (PE). This patient series was also used to compare several methods of performing and interpreting LS images. The final diagnosis was established independently by a separate panel with all available information except for the result of DDA. D-dimer was determined by ELISA (threshold value 500 ng/ml). LS, including perfusion (Q) and pseudo-ventilation (Technegas) (V), was classified according to PIOPED, (1) immediately by the physician on duty, and (2) retrospectively by a blinded panel. A positive (19) or negative (61) diagnosis of PE was achieved in 80 patients, the prevalence of PE being 24%. Only one false-negative was noted on DDA (sensitivity=95%) but there were 42 false-positives (specificity=31%), resulting in a positive predictive value of 30% and a negative predictive value of 95%. Emergency and retrospective interpretations of LS were close (kappa=0.4). In a minority of patients, PE may be excluded with reasonable certainty if DDA is normal, resulting in a significant saving in terms of time and money.     

A prospective,comparative study of ventilation-perfusion scintigraphy and clinical evaluation versus digital subtraction angiography in acute pulmonary thromboembolism

Patients with symptoms of acute pulmonary thromboembolism (APE) of short duration were investigated with digital subtraction angiography (DSA) and ventilation/perfusion lung scintigraphy (V/Q scan), and a standardised clinical evaluation was performed. Forty-six angiograms (96%) were diagnostic at the segmental level and were used as reference. In all V/Q scans classified as normal or of high probability for APE, a complete agreement with DSA was found. In scan categories with low or intermediate probability, where the incidence of APE was 32%, there was considerable inter-observer disagreement. Clinical assessment alone was of limited value, but in patients with low clinical suspicion no APE was found. The results indicate that normal and high probability V/Q scans are very reliable for excluding and identifying APE, respectively, but also that fairly large APE cannot be diagnosed with lung scanning. Subdivision of V/Q scans into more than three categories (normal, high probability and inconclusive) seems to be of no practical value. Using a pulsed sequence technique, high frame rate and central injection, DSA is a valuable clinical tool for diagnosing APE down to the segmental level. Correspondence to: B. Hedlund     

Prospective evaluation of the negative predictive value of V/Q SPECT using 99mTc-Technegas

OBJECTIVE: To verify the negative predictive value of pulmonary ventilation/perfusion scintigraphy with single photon emission computed tomography (V/Q SPECT) in ruling out pulmonary thromboembolism. METHODS: V/Q SPECT using 99mTc-Technegas was performed on 584 patients to rule out pulmonary thromboembolism between October 2004 and July 2005. Pulmonary thromboembolism was defined as any clear-cut vascular mismatch, regardless of size. Indeterminate scans were defined as cases having matching vascular type defects with a corresponding X-ray abnormality, or cases with equivocal mismatches. Other patterns were considered negative for pulmonary thromboembolism. Outcome data was gathered >3 months after the scan. Absence of pulmonary thromboembolism was defined as any patient still alive at least 3 months after the scan, with no anticoagulation treatment and no proof of pulmonary thromboembolism by other techniques, either at the time of the scan or during follow-up, or death by other causes. RESULTS: One hundred and eight patients (19%) had a positive pulmonary thromboembolism reading, 18 (3%) an indeterminate study, and 458 (78%) patients had a negative reading for pulmonary thromboembolism. There were 189 patients with an abnormal chest X-ray. The mean follow-up time was 165 days. Of the 458 patients classified as negative for pulmonary thromboembolism, patients receiving chronic anticoagulation for other causes were excluded from follow-up (n=53), which left 405 patients for final analysis. There were no pulmonary thromboembolism-related deaths in the negative group. Six patients were identified as false negatives. The negative predictive value is estimated at 98.5%. CONCLUSION: SPECT pulmonary scintigraphy using 99mTc-Technegas demonstrates a high negative predictive value and a low indeterminate rate.     

Clinical usefulness of adjusted D-dimer cut-off values to exclude pulmonary embolism in a community hospital emergency department patient population

Background Plasma D-dimer measurement is used in the assessment of the clinical probability of pulmonary embolism (PE), in order to minimize the requirement for pulmonary computed tomography angiography (CTA). Purpose To evaluate whether doubling the threshold value of serum D-dimer from 500 μg/L to 1000 μg/L could safely reduce utilization of pulmonary CTA to exclude PE in our emergency department patient population. Material and Methods Emergency department patients evaluated for PE with a quantitative D-dimer assay and pulmonary CTA were eligible for inclusion. D-dimer values were retrospectively collected in all included patients. Pulmonary CT angiograms were reviewed and scored as positive or negative for PE. Receiver-operating characteristic (ROC) analysis was used to determine the accuracy of quantitative D-dimer measurements in differentiating between positive and negative PE patients as per CTA. Results A total of 237 consecutive patients underwent pulmonary CTA and had a D-dimer measurement performed. Median D-dimer level was 1007 μg/L and in 11 (5%) patients the pulmonary CT CTA was positive for PE. The ROC curve showed an area under the curve (AUC) of 0.91 (P < 0.0001). Increasing the D-dimer threshold value of 500 μg/L to 1000 μg/L increased the specificity from 8% to 52% without changing the sensitivity. Conclusion Adjusting the D-dimer cut-off value for the emergency department community population and patient age increases the yield and specificity of the ELISA D-dimer assay for the exclusion of PE without reducing sensitivity.