下肢静脉病变与肺动脉栓塞关系的研究

目的 探讨下肢静脉病变与肺栓塞（PE）发病之间的关系。方法 对50例正常对照者和200例临床高度怀疑PE和下肢静脉病变的患者,行^99Tc^m-大颗粒聚合白蛋白（MAA）和^99Tc^m-葡聚糖酯（GP）双下肢静脉显像和肺灌注/通气显像,其中15例进行了肺动脉造影。结果 对照组下肢静脉显像和肺灌注/通气显像均显示正常,200例患者肺灌注/通气显像示：175例为多发性PE,25例正常。175例PE患者中128例有下肢静脉病变,占73.14%（128/175例）,其中下肢深静脉血栓（DVT）119例,占68.00%（119/175例）;25例非PE者均有下肢静脉病变。153例下肢静脉病变者中检出PE128例,占83.66%(128/153例）。下肢DVT 119例,其中由髂、股静脉血栓引发PE者101例,占84.87%（101/119例）。结论 双下肢静脉显像与肺灌注/通气显像联合应用,有助于PE及其病因的诊断。     

^99Tc^m—MAA肺显像对深静血栓患者无症状肺栓塞的应用

目的 用^99Tc^m-大颗粒聚合白蛋白（MAA）肺灌注显像研究肾病综合征伴下肢深静脉血栓患者的无症状肺栓塞发病情况。方法 75例肾病综合征伴下肢深静脉血栓而无任何肺部疾病临床症状的患者,均经临床和超声检查证实。所有患者同时进行^99Tc^m-MAA下肢静脉和肺灌注显像,其中45例并行^99Tc^m-MAA肺通气显像。结果 （1）75例患者中有83％（62例）发生下肢Guo窝静脉以下血栓;（2）^99Tc^m-MAA肺灌注显像示61％（46例）患者发生肺栓塞（28例为单侧肺栓塞,18例为双侧肺栓塞）;（3）45例患者^99Tc^m-DTPA肺通气显像未见异常。结论 大部分肾病综合征下肢深静脉血栓患者伴有无症状性肺栓塞;对下肢深静脉血栓患者肺显像应作为常规检查。     

99 Tcm-MAA肺显像对深静脉血栓患者无症状肺栓塞的应用

目的　用99Tcm 大颗粒聚合白蛋白 (MAA)肺灌注显像研究肾病综合征伴下肢深静脉血栓患者的无症状肺栓塞发病情况。方法　 75例肾病综合征伴下肢深静脉血栓而无任何肺部疾病临床症状的患者 ,均经临床和超声检查证实。所有患者同时进行99Tcm MAA下肢静脉和肺灌注显像 ,其中 45例并行99Tcm DTPA肺通气显像。结果　① 75例患者中有 83% (62例 )发生下肢窝静脉以下血栓 ;②99Tcm MAA肺灌注显像示 61% (4 6例 )患者发生肺栓塞 (2 8例为单侧肺栓塞 ,18例为双侧肺栓塞 ) ;③ 45例患者99Tcm DTPA肺通气显像未见异常。结论　大部分肾病综合征下肢深静脉血栓患者伴有无症状性肺栓塞 ;对下肢深静脉血栓患者肺显像应作为常规检查     

放射性核素显像对下肢深静脉病变和肺栓塞的临床观察

为研究下肢深静脉血栓形成与肺栓塞发病之间的关系，对１７１例临床诊断为下肢静脉病变者，使用９９ｍＴｃ大颗粒聚合白蛋白（ＭＡＡ）进行下肢深静脉和肺灌注显像。其中１０例行Ｘ线下肢静脉造影，１８例肺栓塞患者行ＤＳＡ检查，１５例行ＭＲＩ检查。结果：下肢深静脉及肺灌注显像可见１７１例下肢静脉病变患者中有９８例（５７３％）合并肺栓塞；９８例肺栓塞患者中股静脉以上梗阻为７９例，占８０６％。与ＤＳＡ、ＭＲＩ和Ｘ线下肢静脉造影检查的符合率分别为８８９％、８６７％和９００％。故核素下肢深静脉显像结合肺灌注显像是诊断下肢深静脉血栓和肺动脉栓塞的有效方法。     

肺通气/灌注显像诊断不典型亚肺段肺栓塞

目的评价核索肺通气／灌注（V／Q）显像对不典型亚肺段肺栓塞（PE）的诊断价值。方法患者141例，男58例，女83例，年龄（65．67±11．29）岁，其中下肢静脉病变史者14例，糖尿病、高脂血症史者45例，63例近期内行有创性诊断和治疗，另19例均无上述病史或诊疗史。所有患者行常规盼^99Tc^m-MAA和^99Tc^m气体显像后进行1—24个月的抗凝治疗，于治疗后再行肺灌注显像。将抗凝治疗前后肺灌注显像进行对比分析，根据肺内放射性分布的变化判断治疗效果，再结合临床资料及其他影像检查综合判断不典型PE的诊断。结果141例患者肺灌注显像均显示某个肺野内不呈肺段或亚肺段分布的片状或小斑片状放射性分布稀疏区。肺通气显像示肺野内放射性分布基本均匀，未见放射性分布稀疏区。治疗后118例肺灌注显像显示双肺内放射性分布不同程度的增多或均匀。按肺野内放射性分布改善情况标准评价：抗凝治疗后恢复正常35例，显效49例，有效34例。总有效率为83．69％（118／141）。另23例肺内放射性分布无明显变化，视为无效。结论V／Q显像是诊断不典型亚肺段PE的首选方法。     

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。     

99Tcm-technegas肺通气显像的应用及安全性评价

99Tcm 锝气体 (technegas )为近年来使用的肺通气显像剂 ,其颗粒直径细微(5～ 2 0nm) ,大小均匀 ,末梢气管渗透能力强 ,肺通气显像效果佳。且一旦沉积在肺内 ,2 0min内不被清除 ,亦无重新分布 ,适合进行多角度及断层显像 ,并具有制备方便、价格低廉、应用范围广、能量和半衰期合适的特点。现将其应用状况和安全性简要介绍如下。一、临床应用1.99Tcm technegas显像在肺栓塞 (PE)诊断中的应用。肺血管造影术为诊断PE的“金标准” ,但属有创性 ,并有一定危险性。Bomanji等[1 ] 对 175例可疑PE患者行99Tcm technegas肺通气 灌注 (V Q)显像 …     

肺通气/灌注显像与HCTPA诊断肺动脉栓塞的价值

目的　评价核素肺通气 灌注(V Q)显像、螺旋CT肺动脉造影(HCTPA)及血浆D 二聚体在诊断肺动脉血栓中的作用。方法　临床疑为肺动脉栓塞(PE)患者4 2例,男2 6例,女16例,平均年龄( 4 9 18±16 5 6 )岁,均行核素肺V Q显像、HCTPA及血浆D 二聚体测定。其中32例患者在行肺灌注显像时,选择双足背静脉注射肺灌注显像剂,同时完成双下肢静脉显像。结果　4 2例患者中34例经临床诊断为PE ,肺V Q显像诊断PE的灵敏度、准确性和阳性预测值分别为94 12 %、90 4 8%和94 12 % ,HCTPA分别为85 2 9%、83 33%和93 5 5 % ,D 二聚体分别为5 2 94 %、5 7 14 %和90 0 0 %。32例行下肢深静脉显像的PE患者中2 0例有下肢静脉血栓。结论　肺V Q显像无创、安全、简便,诊断PE的灵敏度、准确性高。核素肺显像诊断亚肺段水平PE的能力明显高于HCTPA。     

急性脑血栓性栓塞的核素显像诊断与疗效判断

目的 评价核素显像对急性肺血栓性栓塞的诊断与疗效评价的价值。方法对１０例临床确诊或可疑为肺栓塞的患者进行核素肺灌注、肺通气、肺血栓灶以及双下肢深静脉显像，４例与肺动脉造影或电子束ＣＴ结果对照。８例患者溶栓后复查肺灌注显像，２例患者昨查肺血栓灶显像，结果 肺灌注显像＋下肢深静脉显像对急性肺栓塞诊断的阳性率为１００％，与Ｘ线检查结果基本一致，溶栓后复查提示肺血流均有明显改善乃至恢复正常。结论 核素显像     

急性肺血栓性栓塞的核素显像诊断与疗效判断(附10例报告)

目的评价核素显像对急性肺血栓性栓塞的诊断与疗效评价的价值。方法对１０例临床确诊或可疑为肺栓塞的患者进行核素肺灌注、肺通气、肺血栓灶以及双下肢深静脉显像，４例与肺动脉造影或电子束ＣＴ结果对照。８例患者溶栓后复查肺灌注显像，２例患者复查肺血栓灶显像。结果肺灌注显像＋下肢深静脉显像对急性肺栓塞诊断的阳性率为１００％，与Ｘ线检查结果基本一致，溶栓后复查提示肺血流均有明显改善乃至恢复正常。结论核素显像对诊断急性肺栓塞以及判断疗效是一种准确、可靠的无创性手段。     

Extravasation from venous catheter: a serious complication potentially missed by lung imaging

Three patients were referred for lung ventilation and perfusion (V/Q) imaging with symptoms strongly suggestive of pulmonary embolus (PE). Chest roentgenograms and xenon ventilation studies on all three were normal, save for prominent mediastinal silhouettes and effusions. Technetium-99m macroaggregated albumin (Tc-99m MAA), when injected through the central venous catheter (CVP), revealed mediastinal localization, whereas antecubital injections showed normal pulmonary perfusion. Contrast fluoroscopy introduced through the venous catheter in the first patient defined the extravasation. For patients under strong suspicion of PE, with a venous catheter whose distal tip is seen about the level of the heart on chest radiograph, we recommend administering the perfusion agent slowly through the central catheter to exclude catheter-induced complications. When extravasation is detected, injection of Tc-99m MAA by peripheral vein should be used to exclude PE.     

Equipment availability and diagnostic strategies for suspected pulmonary embolism in Austria

The aim of this study was to investigate equipment availability and current diagnostic strategies for suspected pulmonary embolism (PE) in Austrian hospitals. A questionnaire was sent to the medical directors of all Austrian hospitals with emergency and/or surgical, orthopedic, and medical departments. The questionnaire contained questions regarding the available equipment suitable for the imaging diagnosis of PE, the first-line and second-line imaging tests for patients with suspected PE, and additional lower extremity venous imaging and laboratory tests that complement the diagnostic armamentarium. The return rate for questionnaires was 81% (127 of 157 hospitals). There were 97% of hospitals that had the equipment to perform sonography, 59% could perform pulmonary angiography, 54% spiral CT, 19% ventilation/perfusion (V/P) scintigraphy, and 4% perfusion scintigraphy alone. Spiral-CT angiography (SCTA) was the first-line imaging study for suspected PE in 56% of hospitals, followed by echocardiography and V/P scintigraphy. Lower extremity venous imaging (47%) and, interestingly, V/P scintigraphy (43%), served as second-line imaging tests. D-dimer tests were included in the diagnostic strategy in 74% of hospitals. Spiral-CT angiography is the most commonly used primary method for suspected PE in Austrian hospitals. The V/P scintigraphy is available only in a minority of hospitals to investigate patients with suspected PE. When V/P scintigraphy is available, however, it is employed in a large number of patients per annum.     

Radioaerosol ventilation imaging in ventilator-dependent patients. Technical considerations

The differentiation of pulmonary embolism (PE) from regional ventilatory abnormalities accompanied by reduced perfusion requires contemporary perfusion and ventilation studies. Distinguishing these conditions in ventilator-dependent patients is aided by administering a Tc-99m aerosol to characterize regional ventilation, and by performing a conventional Tc-99m MAA perfusion study. The technique uses a simple "in-house" constructed apparatus. Simple photographic techniques suffice, but computer subtraction of perfusion from the combined perfusion-ventilation image renders interpretation easier if aerosol administration follows perfusion imaging. Multiple defects can be examined in a single study. Excluding normal or near-normal perfusion studies, PE was thought to be present in eight of 16 patients after perfusion imaging alone, but in only one of eight after added aerosol imaging. Angiography confirmed the diagnosis in that patient. Of the eight patients who had abnormal perfusion but were thought unlikely to have PE from the perfusion study alone, two had normal ventilation, and subsequently were shown to have PE by angiography. Because angiography was only performed on patients who were thought to have a high probability of PE on sequential perfusion-ventilation imaging, the true incidence of PE may have been higher. Aerosol ventilation imaging is a useful adjunct to perfusion imaging in patients on ventilators. It requires an efficient delivery system, particularly if aerosol administration follows perfusion imaging, as it does in this study. The major disadvantage of aerosol imaging compared to a gas in intubated patients is the significant bronchial deposition due to retained mucus secretions.(ABSTRACT TRUNCATED AT 250 WORDS)     

Tc-99m-DTPA aerosol and radioactive gases compared as adjuncts to perfusion scintigraphy in patients with suspected pulmonary embolism

To evaluate the clinical utility of improved methods for radioaerosol inhalation imaging, we obtained preperfusion radioaerosol images in 107 patients (mean age = 62 years), who were referred for evaluation of suspected pulmonary embolism (PE). For each patient, we compared six-view aerosol images with accompanying perfusion scans and chest radiographs and with Xenon-133 (Xe-133) or Krypton-81m (Kr-81m) studies. Four observers at four different institutions independently evaluated aerosol-perfusion and gas-perfusion pairs, classifying the probability of PE as low, high, or indeterminate. The radioaerosol images were good to excellent in quality; excessive central deposition of activity was infrequent and did not interfere with image interpretation. The aerosol-perfusion studies showed 86% agreement with Xe-133 perfusion interpretations (n = 299) and 80% agreement with Kr-81m perfusion interpretations (n = 99). These rates of agreement were comparable with those of intraobserver agreement for gas-to-gas and aerosol-to-aerosol comparisons, and higher than interobserver agreement rates. In a limited number (n = 9) of angiographically documented cases, aerosol-perfusion and gas-perfusion studies provided accurate and equivalent diagnoses. The results suggest that radioaerosol inhalation studies, performed with improved nebulizers, are diagnostically equivalent to ventilation imaging as an adjunct to perfusion scintigraphy in evaluating patients with suspected PE.     

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。     

Pulmonary embolism: comprehensive evaluation with MR ventilation and perfusion scanning with hyperpolarized helium-3, arterial spin tagging, and contrast-enhanced MRA

PURPOSE: Development of a comprehensive magnetic resonance (MR) examination consisting of MR angiography (MRA) and MR ventilation and perfusion (MR V/Q) scan for the detection of pulmonary emboli (PE) and assessment of the technique in a rabbit model. MATERIALS AND METHODS: Reversible PE was induced by inflating a non-detachable silicon balloon in the left pulmonary artery of five New Zealand White rabbits. MR V/Q scans were obtained prior to, during, and after balloon deflation. MRA was performed during balloon inflation. MR ventilation imaging was performed after the inhalation of hyperpolarized helium-3. MR perfusion imaging was performed with Flow-sensitive Alternating Inversion Recovery with an Extra Radiofrequency pulse technique (FAIRER). High-resolution contrast-enhanced MR pulmonary angiography was used to confirm the occlusion of the pulmonary artery. All imaging was performed on a 1.5-T whole body scanner with broadband capabilities. RESULTS: High-resolution ventilation images of the lungs were obtained. No ventilation defects were detected before, during, or after resolution of simulated PE. FAIRER imaging allowed visualization of pulmonary perfusion. No perfusion defects were detected prior to balloon inflation. During balloon inflation (PE), there was decreased perfusion in the left lower lobe. After reversal of the PE, there was improved perfusion to the left lower lobe. In analogy to nuclear medicine techniques, acute PE produced a mismatched defect in the MR V/Q scan. MRA verified the occlusive filling defect in the left pulmonary artery. CONCLUSION: High-resolution MRA and MR V/Q imaging of the lung is feasible and allows comprehensive assessment of pulmonary embolism in one imaging session.     

CT and MR in pulmonary embolism: A changing role for nuclear medicine in diagnostic strategy

The goal of this article is to summarize current data on computed tomography (CT) and magnetic resonance (MR) in the diagnosis of acute pulmonary embolism (PE) in relation to the radionuclide ventilation perfusion scan. It is important for the nuclear medicine, CT, and MR communities to develop a shared approach to this disorder. Triage using chest radiographs appears to be a practical method for enhancing both nuclear medicine and CT/MR performance. The realization that there is no clinically available gold standard for the diagnosis of PE suggests that the imaging community should replace impractical and idealistic discussions with more realistic outcome-oriented approaches. A simplified one-step evaluation of the pulmonary arteries and the lower extremity veins for deep venous thrombus can provide a comprehensive examination for PE. CT is currently a more practical diagnostic tool, whereas MR offers a scientific probe for pulmonary physiology including the regional mapping of ventilation-perfusion relationships. Nuclear medicine, CT, and MR thus form an imaging triad for the diagnosis of acute PE.     

Scintigraphic evaluation of pulmonary embolism

Pulmonary embolism (PE) is difficult to diagnose. The clinical signs and symptoms of the disorder are nonspecific, and the results of laboratory tests are undependable. Accordingly, imaging studies have played a major role in evaluation of patients with suspected PE. Chest radiography is an essential part of this imaging evaluation, but is neither sensitive nor specific, per se. The radiograph is used primarily to provide a regional comparison for ventilation-perfusion (V-P) scintigraphy. V-P scintigraphy typically is the pivotal noninvasive approach to diagnosis of PE. Multiview perfusion scintigraphy is a sensitive means for detecting the multiple, wedge-shaped defects characteristic of PE. The perfusion scan's inherent nonspecificity is improved by the ventilation study, which reveals abnormalities of ventilation that account for perfusion defects not caused by PE. Multi-view ventilation imaging with either the xenon gases, Kr-81m or radioaerosols is useful for comparison with perfusion scans. When performed properly and interpreted within the guidelines of current diagnostic schemes for scintigraphy, V-P studies provide approximately 90% reliability for the diagnosis of PE. When used alone or in conjunction with noninvasive studies of deep venous thrombosis, they provide an excellent basis for selection of certain patients for pulmonary angiography, and for other decisions about the clinical management of patients with suspected PE.

     

SPECT imaging of pulmonary emboli with radiolabeled thrombus-specific imaging agents

The safe and accurate diagnosis of acute pulmonary embolism (PE) remains challenging, and many PE-related deaths still occur before the detection of PE. Current techniques detect PE as "negative images," ie, the absence of contrast or downstream perfusion. There would be advantages to obtaining "positive images" of PE, by targeting imaging agents to components that are present primarily on thromboemboli. In addition to providing alternative means of diagnosing acute PE, they would also enable acute PE to be distinguished from other types of pulmonary arterial obstruction, such as unresolved intravascular defects attributable to previous PE. Positive images of PE require imaging agents to bind onto target antigens that are present predominantly on thromboemboli. The "D dimer" regions of polymerized fibrin are present in high concentrations on thromboemboli and are sufficiently accessible to binding. (99m)Tc-lableled anti-D-dimer deimmunized monoclonal antibody Fab' fragments (DI-DD-3B6/22-80B3) bind specifically to thromboemboli, with a thrombus: blood labeling ratio that allows scintigraphic detection. Another thrombus-specific imaging agent is (99m)Tc-labeled apcitide, a synthetic peptide that binds with a high affinity and specificity to the glycoprotein IIb/IIIa receptor on the membrane of activated platelets. Both of these agents have enabled the detection of lower extremity deep vein thrombi by planar scintigraphy. However, even highly radiolabeled PEs are difficult to distinguish by planar scintigraphy from the large blood pool in the heart and lungs. The spatial and contrast resolution inherent to single-photon emission computed tomography (SPECT) scanning allow the in situ imaging of pulmonary emboli that have been bound by radiolabeled thrombus-specific imaging agents. Preliminary trials in humans with acute PE have shown that the emboli can be detected after intravenous administration of (99m)Tc-lableled anti-D dimer, followed by SPECT scanning. Although clinical results are still preliminary, it appears that imaging of pulmonary emboli with SPECT, after administration of radiolabeled thrombus-specific antibody fragments, is accurate and clinically feasible.