  Pulmonary emboli are most often the result of thrombi dislodged from the deep veins of the legs. Risk factors for PE include advanced age, malignant disease, pelvic or abdominal surgery, orthopedic surgery in the lower limbs, prolonged immobilization, obesity, congestive heart failure, and trauma. Dyspnea and chest pain, often pleuritic in nature, are the only symptoms reported by >50% of patients with PE. The chest radiograph is seldom, if ever, diagnostic of PE, and the main role of chest radiography is to identify important alternative diagnoses such as congestive heart failure and pneumonia. On rare occasions, findings suggestive of PE may be present including wedge shaped air-space opacities typically located at the costophrenic sulci, regional hypoperfusion evident as areas of decreased lung attenuation and paucity of vascular markings , and an enlarged pulmonary artery . CT has become the method of choice for imaging PE in clinical routine in most institutions. Negative predictive value of CT has consistently been shown to surpass 96% both with single-detector and multidetector techniques. Underlying lung disease, inpatient status, and results of V/Q scan do not appear to have appreciable effects of the negative predictive value. A clear benefit of CT is the depiction of alternative diagnoses not otherwise suspected when pulmonary embolus is absent. The diagnosis of PE is usually straightforward, relying on the direct observation of a central filling defect surrounded by a rim of contrast in a pulmonary artery. Often emboli lodge at bifurcation points and continue into both branch vessels. A sharp vessel cutoff or absence of vessel filling also provides evidence of pulmonary embolus but may be more difficult to perceive. （以上主题节选自心胸影像病例汇） Notes: 1. embolism [ˈɛmbəˌlɪzəm] n. 栓塞 2. spectrum [ˈspɛktrəm] n. 光谱; 波谱 3. hypotension [ˌhaɪpə'tenʃən] n. 血压过低 4. myocardial [ˌmaɪə'kɑ:dɪrl] adj. 心肌的 5. infarction [ɪnˈfɑ:rkʃn] n. 梗塞形成 6. cardiogenic [ˌkɑ:dɪoʊ'dʒenɪk] adj. 心源性的 7. emboli ['embəli:] n. 栓子 8. orthopedic [ɔ:θə'pi:dɪk] adj.整形手术的 9. dyspnea [dɪsp'ni:ə] n. 呼吸困难 10. pleuritic [plʊ'rɪtɪk] adj. 肋膜炎的 11. costophrenic [kɒs'tɒfrenɪk] 肋膈的（胸膜） 12. sulci [sʊlsɪ] 沟 13. bifurcation [ˌbaɪfə'keɪʃn] n. 分歧，分叉部 【Acute pulmonary embolism (PE)急性肺栓塞】 急性肺栓塞在众多临床疾病中相对常见，从轻微的没有症状的，到检查时偶然发现的亚段肺栓塞，到有生命危险的中央肺栓塞，可引起低血压、心肌梗死、心源性休克。 肺栓塞最常见的原因是下肢深静脉血栓脱落。PE的危险因素包括：年龄、恶性疾病、骨盆或腹部手术、下肢的骨科手术（矫形手术）、长期卧床、肥胖、充血性心衰和创伤。呼吸困难和胸痛，实际上通常由于肋膜炎，据报道，这是半数以上肺栓塞的仅有症状。 平片上很少得出肺栓塞诊断，平片主要用来证明并发的重要征象，得出替代性诊断，比如充血性心衰或肺炎。一些少见的病例中，某些征象可提示肺栓塞。包括：典型位于肋膈角的楔形空腔病变，密度减低、肺血管纹理稀疏的低灌注区，肺动脉扩张。 CT是大多数怀疑肺栓塞患者的常规临床检查方法。CT的阴性预测值和超过96%一种或多种检查方式的结果一致。潜在肺疾病、住院患者、V/Q结果对于阴性预测值似乎没什么预测作用。CT很明确的好处是可以直接描述那些代替性诊断，而不是单纯怀疑是否有肺栓塞。 PE的诊断通畅很直观，直接看到中央充盈缺损、外周动脉壁的征象。栓子通常停留在分叉处，进而进入各分支血管。锐利的血管截断或没有血管的充盈缺损也可提示肺栓塞，但是可能不易发现。 来源：每天朗读一段医学影像学英语文章 圈主 深圳市人民医院放射科副主任医师杨敏洁 |
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Acute PE is a relatively common event with a wide spectrum of clinical presentation that ranges from small asymptomatic and incidentally detected subsegmental PE to life-threatening central PE causing hypotension, myocardial infarction, and cardiogenic shock. 
