1. Pulmonary Embolism Pulmonary Embolism Ma hong Depart. of Medical Imaging, Xuzhou Medical College

2. Introduction Plumonary embolism （ PE ） is one of the commonest preventable causes of death in hospital inpatients. Plumonary embolism （ PE ） is one of the commonest preventable causes of death in hospital inpatients. It is a common cause of mobidity and mortality in postoperative patients, as well as in patients with other risk factors such as prolonged bed rest, malignancy and cardiac failure. It is a common cause of mobidity and mortality in postoperative patients, as well as in patients with other risk factors such as prolonged bed rest, malignancy and cardiac failure.

3. Introduction Symptoms include pleuritic chest pain, shortness of breath, cough and haemoptysis （咯血）, though a large number of pulmonary embolism are clincially silent. Symptoms include pleuritic chest pain, shortness of breath, cough and haemoptysis （咯血）, though a large number of pulmonary embolism are clincially silent.

4. Introduction Despite advances in prophylaxis （预防）, diagnostic modalities, and therapeutic options, venous thromboembolism remains a major health problem Despite advances in prophylaxis （预防）, diagnostic modalities, and therapeutic options, venous thromboembolism remains a major health problem A high mortality rate A high mortality rate As death frequently occurs within the first hours after admission, a rapid and specific diagnosis is required As death frequently occurs within the first hours after admission, a rapid and specific diagnosis is required

5. Introduction As such, the clinical diagnosis of PE is problematic and must be confirmed with imaging studies. As such, the clinical diagnosis of PE is problematic and must be confirmed with imaging studies. These include CXR, CT pulmonary angiography(CTPA),ventilation/perfusion nuclear lung scan(V/Q scan), and pulmonary angiography. These include CXR, CT pulmonary angiography(CTPA),ventilation/perfusion nuclear lung scan(V/Q scan), and pulmonary angiography.

6. CXR The initial imaging investigation in all patients is CXR. The initial imaging investigation in all patients is CXR. Signs of PE on CXR include pleural effusion,localized area of consolidation contacting a pleural surface or a localized area of collapse. Signs of PE on CXR include pleural effusion,localized area of consolidation contacting a pleural surface or a localized area of collapse. These signs are quite non-specific and the main role of CXR in this context is to diagnose other causes for the patient's symptoms such as pneumonia. These signs are quite non-specific and the main role of CXR in this context is to diagnose other causes for the patient's symptoms such as pneumonia.

7. Imaging Assessment of PE Computed Tomography  Helical and mutislice CT allow imaging of the thorax in a single breath hold and imaging of the entire pulmonary vascular bed during optimum peak contrast enhancement.  Obstruction of the pulmonary vascular bed (PVB),Pulmonary emboli are seen on CTPA as filling defects within contrast- filled blood vessels.

8. CTPA CT pulmonary angiography (CTPA) has progressively （日 渐，逐步地） been established as the frontline imaging modality for the diagnosis of pulmonary embolism (PE) CT pulmonary angiography (CTPA) has progressively （日 渐，逐步地） been established as the frontline imaging modality for the diagnosis of pulmonary embolism (PE)

10. Rational use of imaging in the diagnosis of PE A number of factors have contributed to the overuse of CTPA. These include: A number of factors have contributed to the overuse of CTPA. These include: The wide availability of multislice CT scanners. The wide availability of multislice CT scanners. The high level of accuracy of CTPA. The high level of accuracy of CTPA. The ability of CTPA to make alternative diagnoses. The ability of CTPA to make alternative diagnoses. The popularization of the concept of the"triple-rule-out":contrast- enhanced CT in patients with chest pain to rule out pulmonary embolism,coronary artery disease and aortic dissection. The popularization of the concept of the"triple-rule-out":contrast- enhanced CT in patients with chest pain to rule out pulmonary embolism,coronary artery disease and aortic dissection. Wide public awareness of PE with popular press coverage of cases of PE following long-haul air travel. Wide public awareness of PE with popular press coverage of cases of PE following long-haul air travel. The overuse of CTPA is not only expensive but also has major implications with respect to radiation dose. The overuse of CTPA is not only expensive but also has major implications with respect to radiation dose.

11. Introduction CTPA has also become more frequently included in recommended diagnostic algorithms （方法） CTPA has also become more frequently included in recommended diagnostic algorithms （方法） CTPA allows a more comprehensive assessment of the clot burden in the pulmonary arteries (PAs), associated underlying lung disease, and other causes of acute chest pain CTPA allows a more comprehensive assessment of the clot burden in the pulmonary arteries (PAs), associated underlying lung disease, and other causes of acute chest pain We have to know how to evaluate the severity of the current episode of PE at CTPA, giving clinicians relative imaging findings We have to know how to evaluate the severity of the current episode of PE at CTPA, giving clinicians relative imaging findings

12. Assessment of the Severity of PE Clinical identification of high-risk patients Circulatory failure and systemic hypotension as predictors of poor prognosis Circulatory failure and systemic hypotension as predictors of poor prognosis Other clinical predictors of poor outcome Other clinical predictors of poor outcome  Age over 70 years  coexisting congestive heart failure  chronic obstructive pulmonary disease

13. Some Potential Findings Assessment of Pulmonary Perfusion The extent of PE can be assessed by quantification of perfusion defects The extent of PE can be assessed by quantification of perfusion defects  Dual energy CTPA: fusion of morphology and function of whole lungs

14. Some Potential Findings Clot Burden at the Level of Lower Limb and Abdominal Veins Clot Burden at the Level of Lower Limb and Abdominal Veins Clots in the PAs influence the cardiopulmonary status of the patients, the major risk of death is from recurrent PE, which in more than 90% of the patients originates from lower limb veins Clots in the PAs influence the cardiopulmonary status of the patients, the major risk of death is from recurrent PE, which in more than 90% of the patients originates from lower limb veins Imaging and estimation of the volume of the clot burden in lower limb veins may therefore be another important CT finding to consider for management, treatment, and prognosis in patients with PE Imaging and estimation of the volume of the clot burden in lower limb veins may therefore be another important CT finding to consider for management, treatment, and prognosis in patients with PE

16. Thank you!