PROSPECTIVE INVESTIGATION OF PULMONARY EMBOLISM DX II

这是一项多中心合作研究，旨在确定对比增强螺旋计算机断层扫描（螺旋CT）诊断急性肺栓塞（PE）的敏感性、特异性、阳性预测值和阴性预测值。肺栓塞是常见的，但往往未确诊和致命的。通气/灌注肺扫描是最常用的检查方法。然而，72%的疑似PE患者和57%的确诊PE患者无法诊断。肺血管造影是目前明确的诊断测试，但由于发病率、不适、费用和社区医院缺乏可用性，使用它存在犹豫。对比增强螺旋CT是一种几乎无创的检查，通过显示肺动脉血栓的轮廓，为PE的明确诊断提供了可能性。然而，其在PE诊断中的应用尚不清楚。尽管螺旋CT尚未得到充分的验证，但许多医院的医生现在将其作为PE的最终和唯一诊断测试，或者作为通气/灌注肺扫描不能诊断的患者的最终测试。这可能导致过度治疗或治疗不足，这两种情况都有严重的潜在并发症。螺旋CT在PE诊断中的作用需要准确的评估，本研究将通过与肺血管造影的比较来进行评估。该提案的优势在于：1)就诊断不足导致的生命损失和过度诊断导致的大出血而言，PE问题的重要性；2)PE诊断新技术的潜在适用性将得到广泛应用；3)研究者团队。无创腿部检查，特别是静脉超声检查，允许通过基于静脉血栓栓塞性疾病（PE或深静脉血栓形成）、通气/灌注肺扫描或下肢压缩超声的治疗策略。对于既往无肺栓塞的患者，将根据高概率通气/灌注肺扫描诊断肺栓塞；对于既往无深静脉血栓形成的患者，将根据肺血管造影或下肢压缩超声诊断肺栓塞。静脉超声检测深静脉血栓形成可作为PE诊断的替代手段。肺栓塞将通过肺血管造影或几乎正常或正常通气/灌注肺扫描排除，未治疗患者随访无不良结果（即PE或DVT）。在进行低概率通气/灌注肺扫描的患者中，每隔1周进行2次阴性静脉压迫超声检查，然后随访6个月不治疗，每隔1周随访6个月不治疗，不复发PE或DVT。该方案与标准诊断策略相似，没有使患者完全承担获取数据的风险。

This is a multicenter collaborative study to determine the sensitivity, specificity, positive predictive value, and negative predictive value of contrast enhanced spiral computed tomography (spiral CT) for the diagnosis of acute pulmonary embolism (PE). Pulmonary embolism is common, yet frequently undiagnosed and fatal. Ventilation/perfusion lung scans are the most commonly used test. However, they are nondiagnostic in 72 percent of patients with suspected PE, and in 57 percent of patients with proven PE. Pulmonary angiography is the currently definitive diagnostic test, but there is hesitancy to use it because of morbidity, discomfort, cost, and lack of availability in community hospitals. Contrast enhance spiral CT is a nearly noninvasive test that offers the possibility of a definitive diagnosis of PE by showing the outline of the thrombus in a pulmonary artery. However, its utility in the diagnosis of PE is unknown. Even though spiral CT has not been adequately validated, physicians at many hospitals now use it as a definitive and only diagnostic test for PE, or as a definitive test in patients in whom the ventilation/perfusion lung scan is nondiagnostic. This could lead to overtreatment or undertreatment, both of which have serious potential complications. The role of spiral CT in the diagnosis of PE requires an accurate evaluation which will be made in this investigation by comparison with pulmonary angiography. The strengths of this proposal are: 1) the importance of the problem of PE in terms of lives lost from underdiagnosis, and major bleeding from overdiagnosis 2) the potential applicability of a new technology for the diagnosis of PE that will have widespread availability and 3) the investigator team. Noninvasive leg tests, particularly venous ultrasonography, permit a strategy of management by treatment on the basis of venous thromboembolic disease (PE or deep venous thrombosis), ventilation/perfusion lung scan, or compression ultrasound of the lower extremities. Pulmonary embolism will be diagnosed on the basis of a high probability ventilation/perfusion lung scan in patients with no prior PE, pulmonary angiography, or compression ultrasound of the lower extremities in patients with no prior deep venous thrombosis. Deep venous thrombosis detected by venous ultrasound will serve as a surrogate for the diagnosis of PE. Pulmonary embolism will be excluded by pulmonary angiography, or a nearly normal or normal ventilation/perfusion lung scna with no adverse outcome (i.e. PE or DVT) on follow-up of untreated patients. Among patients with a low probability ventilation/perfusion lung scan, PE will be excluded by 2 negative venous compression ultrasound studies at 1 week intervals followed by 6 months of follow-up with no treatment and at 1 week intervals, followed by 6 months of follow-up with no treatment and no recurrent PE or DVT. The protocol parallels standard diagnostic strategy, without subjecting the patients to risk entirely for the acquisition of data.