Comparison of perfusion lung scanning and angiography in the estimation of vascular obstruction in acute pulmonary embolism

To determine the relationships between perfusion scan defect and angiographic severity (Miller index) in acute pulmonary embolism, we analysed examinations obtained before and after thrombolytic therapy in 34 consecutive patients free from underlying cardiopulmonary disease. The overall agreement between the two techniques was excellent (r = 0.82; mean absolute difference = 2.8%), although when embolic involvement was extensive (greater than 50% angiographic obstruction), the perfusion scan moderately underestimated (4%) the defect seen angiographically. These findings suggest that the pulmonary lung scan is a reliable method of assessing the initial pulmonary vascular obstruction as well as of quantifying any changes induced by or associated with the treatment.     

MR肺通气联合灌注成像的动物模型研究

目的 探讨氧增强MR肺通气成像联合肺灌注成像诊断气道阻塞和肺栓塞(PE)病变的可行性和价值。方法 对8只犬通过肺段动脉水平注入凝胶海绵颗粒复制周围型PE模型，其中5只经自制球囊导管插入二级气道又建立气道阻塞模型。通过吸纯氧前后的图像减影可获得氧增强MR肺通气图像。利用对比剂首次通过法可进行MR肺灌注成像。观察MR肺通气和灌注成像的表现，并与大体病理解剖、核素肺通气-灌注成像和肺血管造影进行对照。结果 MR肺通气和灌注成像在气道阻塞区的表现相匹配，但在肺栓塞区不匹配。气道阻塞区在MR肺通气成像中的缺损区域小于核素肺通气成像。根据信号强度随时间变化曲线，肺灌注异常区可分为灌注缺损和减低区。MR肺通气联合灌注成像诊断肺栓塞的敏感度和特异度分别为75．0％和98．1％；其诊断结果与核素肺通气一灌注成像和肺血管造影的一致性较好(K=0．743、0．899)。结论 氧增强MR肺通气成像联合肺灌注成像可用来诊断肺内气道和血管异常，该方法与核素肺通气-灌注成像类似，并能提供量化的功能信息和更高的时间、空间分辨率，具有临床应用价值。     

Digital subtraction angiography in abnormal perfusion scintigraphy of the lungs

A normal lung perfusion isotope scan can exclude pulmonary emboli. However, the demonstration of lung emboli presents problems, as an abnormal lung perfusion scan can have various causes. Some of these can be excluded if the perfusion scan is assessed in combination with a chest X-ray and a ventilation scan. In this study, 21 patients with an abnormal perfusion scan were also examined using digital subtraction angiography (DSA) of the lungs. With the help of DSA it was possible to differentiate between the various causes of a lung perfusion defect on the isotope scan by having a sufficiently reliable pulmonary angiogram. From experience it appears that the quality of the pulmonary angiogram confined to the first three divisions obtained with DSA, is comparable with that from a conventional pulmonary angiogram. A perfusion isotope scan is the initial screening modality for suspected lung emboli, if this shows an abnormality, DSA seems to be indicated as the next step.     

多层螺旋CT对肺栓塞影像表现及与其严重性关系的评价

目的 评价多层螺旋CT肺栓塞影像表现及与其严重性的关系.资料与方法 回顾性分析104例临床诊断肺栓塞患者的临床及影像学资料,测量心血管参数:主肺动脉直径、右心室短轴最大径(RVMSA)、左心室短轴最大径(LVMSA)及RVMSA/LVMSA比值,计算CT肺动脉成像(CTPA)阻塞指数,评价CTPA上栓子的形态和与双能量CT(DECT)上灌注缺损的关系及CTPA阻塞指数与心血管测量参数的关系.结果 104例中,32例因图像丢失(n=10)、CTPA图像欠佳,不满足测量要求(n=9)或未行CTPA检查(n=13),故只对72例患者的影像学资料进行分析评价.完全闭塞型肺栓塞DECT表现为整个肺叶灌注降低或某个肺段灌注缺损,部分闭塞型DECT表现为灌注降低或正常.CT阻塞指数与心血管测量参数具有一定的相关性(P<0.05),以CT阻塞指数与RVMSA/LVMSA比值相关性最高(r=0.519,P<0.001).结论 肺灌注异常与否取决于肺动脉栓塞的程度;CT肺动脉阻塞指数可用于评价肺栓塞的严重性.     

Changes in perfusion scintigraphy in the first days of heparin therapy in patients with acute pulmonary embolism

Patients with suspected pulmonary embolism often receive heparin therapy for hours to days before ventilation/perfusion scintigraphy is completed. We assessed to what extent the lung scan classification and pulmonary vascular perfusion changed over a period of 2-4 days of full anticoagulant therapy. In 312 consecutive patients with at least one segmental perfusion defect on the initial perfusion scan, classification of both the initial and the final lung scan allowed us to study alteration in scan classification. Changes in pulmonary perfusion were assessed scintigraphically in a subgroup of 64 patients with proven pulmonary embolism. Among 79 patients with an initial high-probability lung scan, the final scan remained high probability in 77 whereas it became non-diagnostic and normal in one patient each. The lung scan classification did not change in any of the 233 patients who initially had a non-diagnostic scan. Thus, a different lung scan category was observed in only 2 out of 312 patients (0.6%; 95% CI 0.1%-2.3%). The mean pulmonary perfusion at baseline in the subgroup of 64 patients with pulmonary embolism was 62% (SD ᆥ%; range 26%-89%). A mean absolute improvement in pulmonary perfusion of only 4%ᆟ% (NS) was observed in the 2-4 days of observation. It is concluded that intravenous heparin therapy for a period of 2-4 days has only a minimal influence on the diagnostic lung scan classification and induces only minor changes in pulmonary vascular obstruction in the majority of patients.     

Changes in perfusion scintigraphy in the first days of heparin therapy in patients with acute pulmonary embolism

Patients with suspected pulmonary embolism often receive heparin therapy for hours to days before ventilation/perfusion scintigraphy is completed. We assessed to what extent the lung scan classification and pulmonary vascular perfusion changed over a period of 2-4 days of full anticoagulant therapy. In 312 consecutive patients with at least one segmental perfusion defect on the initial perfusion scan, classification of both the initial and the final lung scan allowed us to study alteration in scan classification. Changes in pulmonary perfusion were assessed scintigraphically in a subgroup of 64 patients with proven pulmonary embolism. Among 79 patients with an initial high-probability lung scan, the final scan remained high probability in 77 whereas it became non-diagnostic and normal in one patient each. The lung scan classification did not change in any of the 233 patients who initially had a non-diagnostic scan. Thus, a different lung scan category was observed in only 2 out of 312 patients (0.6%; 95% CI 0.1%-2.3%). The mean pulmonary perfusion at baseline in the subgroup of 64 patients with pulmonary embolism was 62% (SD +/-17%; range 26%-89%). A mean absolute improvement in pulmonary perfusion of only 4%+/-11% (NS) was observed in the 2-4 days of observation. It is concluded that intravenous heparin therapy for a period of 2-4 days has only a minimal influence on the diagnostic lung scan classification and induces only minor changes in pulmonary vascular obstruction in the majority of patients.     

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。     

Very low probability interpretation of V/Q lung scans in combination with low probability objective clinical assessment reliably excludes pulmonary embolism: data from PIOPED II.

Use of a very low probability interpretation of ventilation/perfusion (V/Q) lung scans, if verified by prospective evaluation to have a low positive predictive value (PPV), will reduce the number of nondiagnostic interpretations of V/Q scans and may be particularly useful in patients with a relative contraindication to CT. The purpose of this investigation was to test the hypothesis that a very low probability interpretation of the V/Q scan has a PPV of <10%. METHODS: Data are from PIOPED II (Prospective Investigation of Pulmonary Embolism Diagnosis II). Very low probability criteria are (a) nonsegmental perfusion abnormalities, (b) perfusion defect smaller than corresponding radiographic lesion, (c) > or =2 matched V/Q defects with regionally normal chest radiograph, (d) 1-3 small segmental perfusion defects (<25% of a segment), (e) solitary triple matched defect in middle or upper lung zones, (f) stripe sign around the perfusion defect(s), and (g) perfusion defect from pleural effusion equal to one third or more of the pleural cavity with no other perfusion defect. RESULTS: A very low probability consensus interpretation of the V/Q scan was made in 56% of patients. The PPV of a very low probability interpretation of the V/Q scans was 36 of 440 patients (8.2%). Among patients with suspected pulmonary embolism who had a low clinical probability objective clinical assessment and a very low probability V/Q scan, the PPV was 8 of 259 patients (3.1%). Among women < or =40 y, the PPV of the very low probability V/Q with a low objective clinical assessment was 1 of 50 (2%). CONCLUSION: The very low probability V/Q scan together with a low probability clinical assessment reliably excludes pulmonary embolism.     

Pulmonary embolism from pulse-spray pharmacomechanical thrombolysis of clotted hemodialysis grafts: urokinase versus heparinized saline

PURPOSE: To compare the frequency and extent of pulmonary embolism (PE) occurring during pulse-spray pharmacomechanical thrombolysis (PSPMT) of clotted hemodialysis grafts with use of either urokinase (UK) or heparinized saline (HS). Postintervention primary patency and complication rates were compared for each method of thrombolysis. METHODS AND MATERIALS: Twenty-seven patients were enrolled in this prospective, randomized, double-blind study evaluating PE with two PSPMT agents. The doses of heparin were similar between groups. The only variable was that one group of patients received UK and the other received HS. In two cases, the venous anastomosis could not be crossed. Eleven patients were treated with UK and 14 with HS. Nuclear medicine perfusion lung scans were performed before treatment and after graft declotting procedures. Lung perfusion was quantified to 10% of a pulmonary segment (0 = normal perfusion, 1 = segmental perfusion defect), with nine segments counted for each lung. RESULTS: Baseline nuclear medicine perfusion lung scan results were abnormal (> or = 20% segmental perfusion defect) in 19 patients (70.4%). New PE (one or more pulmonary segments) occurred in two patients treated with UK (18.2%) and nine patients treated with HS (64.3%; P = .04). All cases of PE were asymptomatic. Quantitative global pulmonary perfusion analyses revealed that treatment with UK improved flow to 0.2 +/- 2.0 pulmonary segments, whereas treatment with HS decreased perfusion to 1.0 +/- 1.7 segments (P = .16, NS). Although postintervention primary patency rates were similar according to life-table analysis (P = .76, NS), complication rates were higher with use of HS (n = 4, 28.6%) than with use of UK (n = 2, 18.2%) (P = .6, NS). CONCLUSIONS: All PE were asymptomatic during PSPMT, but treatment with UK reduced the rate of PE and tended to result in smaller defects in lung scan results. Most patients undergoing hemodialysis have abnormal baseline perfusion scan results, but PSPMT with UK improved many of them. The postintervention primary patency rates were similar between groups, but complications were more frequent after treatment with HS.     

双能量CT肺灌注及血管成像与核素肺通气灌注成像诊断肺栓塞的对照研究

目的 通过与核素肺通气灌注显像比较,评价双能量CT肺血管成像(DE-CTPA)及双能量CT肺灌注成像(DE-CTLP)技术诊断肺栓塞的能力.方法 比较50例临床怀疑肺栓塞的患者DE-CTPA、DE-CTLP及核素肺通气灌注显像结果,以非线性相关检验比较DE-CTPA显示肺血管腔内充盈缺损与DE-CTLP显示灌注缺损之间的相关性,以核素为参考标准,应用一致性检验方法(Kappa检验)对照分析两者之间的一致性及DE-CTLP诊断肺栓塞的敏感性和特异性.结果 (1)50例临床怀疑肺栓塞患者中,4例CT图像质量差,不能评价.余46例共920个有效肺段中,DE-CTPA显示262个肺段肺血管腔内充盈缺损,DE-CTLP显示266个肺段明确灌注缺损.核素肺通气灌注扫描显示268个肺段灌注与通气不匹配.(2)DE-CTLP与DE-CTPA两者间显著相关(r=0.883,P<0.01);DE-CTLP与核素肺通气灌注显像的一致性良好(Kappa=0.940,P<0.01);以核素肺通气灌注成像为诊断参考标准,应用DE-CTLP诊断肺栓塞的阳性预测值95.5%(279/292),阴性预测值98.3%(641/652),敏感性96.2%(279/290),特异性98.0%(641/654).(3)应用CareDose 4D技术,DE-CTPA和DE-CTLP患者平均射线损伤剂量为(4.37±0.47)mSv.结论 应用DE-CTPA和DE-CTLP技术可以在一次扫描中同时获得常规CT肺血管成像的血管形态学信息和肺实质血流灌注情况,为临床诊断肺栓塞提供直观、有效的综合影像信息.     

Correlation of pulmonary 99mTc-DTPA ventilation and 99mTc-MAA perfusion scans with pulmonary function tests in asymptomatic asthmatic children

Our objective was to examine and correlate 99mTc-diethylenetriaminopentaacetic acid (99mTc-DTPA) ventilation and 99mTc-macroaggregated albumin (99mTc-MAA) perfusion (V/Q) lung scans with spirometry in asymptomatic asthmatic children. We evaluated 89 subjects (age range, 6-15 years; mean age, 9.4 years), all with at least 70% predicted forced expiratory volume in 1 s (FEV(1)). There were four V/Q scan patterns: normal in 38 (42.7%), inhomogeneous ventilation in 11 (12.4%), matched defects in 25 (28.3%) and mismatched perfusion defects in 13 (14.6%). The maximal mid-expiratory flow rate (MMEF) of the normal scan group was significantly different from that in the other groups. The MMEF of the inhomogeneous group was significantly different from that in the matched defect group and the mismatched perfusion defect group. No other significant differences in spirometric indices were found. In two children with perfusion defects, pulmonary arteriograms demonstrated no obstructive lesions. In conclusion, lung scans provide diagnostic information in asymptomatic asthmatic children, even when they are uncooperative. Abnormal scans are common in these children and are significantly correlated with reduced MMEF (% predicted), reflecting small airway flow obstruction. The pathophysiology of V/Q defects in asymptomatic asthmatic children warrants further investigation.     

Diagnosis of pulmonary embolism with spiral CT as a second procedure following scintigraphy

Our objective was to evaluate, in a routine clinical setting, the role of spiral CT as a second procedure in patients with clinically suspected pulmonary embolism (PE) and abnormal perfusion scan. We prospectively studied the role of spiral CT in 279 patients suspected of PE. All patients started their diagnostic algorithm with chest radiographs and perfusion scintigraphy. Depending on the results of perfusion scintigraphy, patients proceeded to subsequent levels in the algorithm: stop if perfusion scintigraphy was normal; CT and pulmonary angiography if subsegmental perfusion defects were seen; ventilation scintigraphy followed by CT when segmental perfusion defects were seen; and pulmonary angiography in this last group when results of ventilation/perfusion scintigraphy and CT were incongruent. Reference diagnosis was based on normal perfusion scintigraphy, high probability perfusion/ventilation scintigraphy in combination with abnormal CT, or pulmonary angiography. If PE was present, the largest involved branch was noted on pulmonary angiography, or on spiral CT scan in case of a high-probability ventilation/perfusion scan and a positive CT scan. A distinction was made between embolism in a segmental branch or larger, or subsegmental embolism. Two hundred seventy-nine patients had abnormal scintigraphy. In 27 patients spiral CT and/or pulmonary angiography were non-diagnostic and these were excluded for image analysis. Using spiral CT we correctly identified 117 of 135 patients with PE, and 106 of 117 patients without PE. Sensitivity and specificity was therefore 87 and 91%, respectively. Prevalence of PE was 53%. Positive and negative predictive values were, respectively, 91 and 86%. In the high-probability group, sensitivity and specificity increased to 97 and 100%, respectively, with a prevalence of 90%. In the non-high probability-group sensitivity and specificity decreased to 61 and 89%, respectively, with a prevalence of 25%. In a routine clinical setting single-detector spiral CT technology has limited value as a second diagnostic test because of low added value in patients with a high-probability lung scan and low sensitivity in patients with non-high-probability lung scan result.     

Scintigraphic determination of severity in pulmonary parenchymal damage in patients with atrial septal defect

According to the pattern observed on a lung perfusion scan, patients with atrial septal defect (ASD) were classified into three stages: stage I, normal perfusion (n = 15); stage II, apical prone perfusion (n = 22); and stage III, mottled perfusion (n = 23). These stages were compared with hemodynamic data obtained from cardiac catheterization and with the right ventricular ejection fraction (RVEF). Staging from I to III correlated well with pulmonary arterial pressure, and patients in stage III showed a significant increase in pulmonary arteriolar resistance and a significant decrease in Qp/Qs. There was no significant difference in RVEF between the stages. We concluded that the scintigraphic severity determined by lung perfusion scan could be valid for evaluating the extent of pulmonary parenchymal damage in patients with ASD.     

多层螺旋CT在肺动脉栓塞诊断中的应用价值

目的 研究多层螺旋CT在肺动脉栓塞诊断中的临床应用，着重研究亚段肺动脉栓塞的诊断价值。方法 共34例，下肢深静脉血栓16例，近期大手术史11例，肺癌1例，不明原因6例。34例均使用GE Light Speed Plus多层螺旋CT(MSCT)行平扫及造影增强扫描，1次采集4层图像。结果 分析34例共1824支肺动脉分支，其中507支肺动脉分支显示了栓塞，占27．8％。在680支肺段动脉中，246支显示了栓塞，占36．2％；而亚段肺动脉1041支中，141支显示了栓塞，占13．5％。平扫肺动脉栓塞的间接征象为肺纹理稀少19例，肺动脉高压2例，胸水16例，胸膜下梗死灶共41个，梗死灶多发11例，单发12例，双肺6例。1例慢性栓塞栓子钙化，极为少见。造影增强后肺动脉栓塞的直接征象为不同程度的肺动脉分支充盈缺损。充盈缺损有4种表现形式：中心型57支，偏心型160支，附壁血栓131支，完全阻塞型159支。结论 多层螺旋CT肺动脉造影是诊断肺动脉栓塞的快速、有效、无创伤的诊断方法，尤其对亚段肺动脉栓塞是一种先进的方法，可以代替肺动脉造影，可与电子束CT媲美，可能成为诊断肺动脉栓塞的首选方法。     

The effect of verapamil on the restoration of myocardial perfusion and functional recovery in patients with angiographic no-reflow after primary percutaneous coronary intervention

OBJECTIVE: Angiographic thrombolysis in myocardial infarction (TIMI) flow grade < or = 2 after primary percutaneous coronary intervention (PCI), defined as angiographic no-reflow, predicts poor functional recovery in patients with acute myocardial infarction. We investigated the effect of verapamil on the restoration of myocardial perfusion and functional recovery in patients with angiographic no-reflow after PCI. METHODS: 99mTc tetrofosmin single photon emission computed tomographic (SPECT) imaging was performed (before, immediately after and 1 month after PCI) in 101 consecutive patients with acute myocardial infarction. The defect score was calculated as the sum of perfusion defect in a 13-segment model (scores of 3, complete defect to 0, normal perfusion). The asynergic score, defined as the number of asynergic segments, was assessed by echocardiography before and 1 month later. Multiple logistic regression analysis was performed to elucidate the effect of verapamil administration. RESULTS: Of 101 patients, 32 (31%) had angiographic no-reflow and were divided into two groups: 18 patients with verapamil (group 1) and 14 patients without verapamil (group 2). Sixty-nine patients had TIMI grade 3 reflow after PCI (group 3). The change in the defect score 1 month after PCI in group 1 was significantly larger than that in group 2 (P = 0.003). The asynergic score improved more at 1 month in group 1 compared to that in group 2 (P = 0.007). Moreover, logistic regression analysis revealed that TIMI grade reflow < or = 2 after PCI (P = 0.04, OR = 5.51), the defect score before PCI (P = 0.03, OR = 1.15), the asynergic score before PCI (P = 0.01, OR = 0.64) and the administration of verapamil (P = 0.002, OR = 22.4) were independently associated with successful myocardial reperfusion immediately after PCI. CONCLUSIONS: Intracoronary verapamil restored myocardial perfusion in patients with angiographic no-reflow after PCI and lead to better functional recovery after acute myocardial infarction.     

Electrocardiographic findings in pulmonary thromboembolism--comparison with lung perfusion scan and echocardiographic findings

This study investigated the usefulness of electrocardiography (ECG) in pulmonary thromboembolism (PTE), compared with lung perfusion scan and echocardigraphic findings on evaluation of the severity. We checked ECG findings associated with PTE at hospital admission, with the seven abnormal findings described by Sreeram N, et al. On Lung perfusion scan, severity of perfusion defect was assessed total defect score (TDS), calculated as the sum of the scores for all 18 segment of lung. On echocardiography, severity of right ventricular overload was assessed. The number of the seven ECG abnormal findings and TDS were larger in patients with the right ventricular overload (p < 0.01). The number of the ECG findings was positively correlated with TDS (r = 0.75). The number of abnormal ECG findings in PTE is associated with the severity evaluated by lung perfusion scan and echocardiography.     

The value of pulmonary angiography for the differential diagnosis of pulmonary embolism

The aim this study was to evaluate potential additional information of pulmonary angiography in patients with suspected pulmonary embolism and non-diagnostic lung scan findings. In a series of 150 patients who underwent pulmonary angiography for suspected venous thromboembolism, the images for potential alternative diagnoses other than pulmonary embolism were evaluated. All patients had non-diagnostic lung scan findings. Angiography was performed both by conventional and by digital subtraction angiography techniques. Images were evaluated by at least two experienced readers. Angiograms were scored for both presence or absence of pulmonary embolism, as well as other diagnoses. Pulmonary embolism was proven in 40 patients (27 %) and excluded in 105 patients (70 %), whereas non-interpretable images were obtained in 5 patients (3 %). A range of alternative diagnoses were detected by angiography: atelectasis (n = 24), pleural effusion (n = 15), pneumonia (n = 11), emphysematous bullae (n = 8), neoplasm (n = 3), atrial septum defect (n = 2), chronic thromboembolism (n = 1), and other diagnoses (n = 3). Overall, only 54 patients (36 %) had completely normal angiograms. Although pulmonary angiography remains the reference method for the diagnosis of pulmonary embolism, one has to be aware of other, often unexpected, but equally important findings which could influence the management of the patient. This aspect of pulmonary angiography has been insufficiently emphasized in the literature. Received: 2 April 1998; Revision received: 22 July 1998; Accepted: 4 November 1998     

Pre-operative evaluation with MR in tetralogy of fallot and pulmonary atresia with ventricular septal defect

Purpose: To assess whether MR imaging could replace angiography in pre-operative evaluation of patients with tetralogy of Fallot and pulmonary atresia with ventricular septal defect (VSD), especially since the surgical correction was done earlier than was previously the rule.Material and Methods: Fourteen patients with tetralogy of Fallot (n=10) or pulmonary atresia with VSD (n=4), mean age 7.5±4.4 months, were evaluated with angiocardiography and MR before definitive surgical correction.Results: There was good diagnostic agreement between the two modalities when evaluating right ventricular outflow obstruction; 86% for valvular and 93% for supravalvular stenosis, but the agreement was somewhat lower for the subvalvular obstruction (57%). Surgery findings, however, were in favour of MR in 5 patients concerning the subvalvular right ventricular outflow tract obstruction. MR images identified all stenoses in the right and left pulmonary arteries, but overlooked one stenosis in the main pulmonary artery. MR could evaluate patency in all palliative shunts.Conclusion: Even in this young age group, MR imaging offers a good alternative to angiocardiography for the pre-operative evaluation of the right ventricular outflow tract, the main pulmonary artery and the proximal right and left pulmonary arteries, before definitive surgical correction of tetralogy of Fallot and pulmonary atresia with VSD.     

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。     

Utility of Tc-99m DTPA aerosol inhalation scans following perfusion lung scans in the diagnosis of pulmonary embolism

The authors report their experience with the use of Tc-99m DTPA aerosol following a perfusion lung scan. The study includes 422 consecutive patients with suspected pulmonary embolism. The final diagnosis was determined by (a) clinical follow-up for 2 months or more, (b) pulmonary angiography, or (c) autopsy. There were 79 patients (19%) who had a normal or near-normal perfusion study and in whom no aerosol study was required. Interpretation groups were classified and divided as follows: Normal or low probability 281 (66.5%) High probability 75 (18.0%) Intermediate 60 (14.0%) Technically inadequate 6 (1.5%) There was autopsy or angiographic confirmation of 72 patient studies with confirmation of the scan diagnosis in 29 of 31 classified as normal or low probability and 24 of 25 classified as high probability. The background perfusion albumin activity was not computer-subtracted from the combined aerosol-perfusion image. Technical improvements included the use of eight standard views for both the perfusion and the subsequent aerosol scan, and the use of 75 mCi (2,775 MBq) of Tc-99m DTPA in the radioaerosol nebulizer. This allowed for easy accumulation of more than three times the count rate in a posterior aerosol image when compared with the previous posterior perfusion image. The authors' experience shows that the perfusion lung scan followed by this radioaerosol technique is a reliable means to evaluate suspected pulmonary embolism.