This invasive procedure has an estimated morbidity and mortality of 3.5% to 6% and 0.2% to 0.5%, respectively [32,33]. MRA Pulmonary Arteries Without and With IV Contrast MRA can identify emboli in the central and segmental pulmonary arteries [34-37] among patients with low or intermediate probability with positive D-dimer [38]. However, limitations were identified by the PIOPED III trial Suspected Pulmonary Embolism MRA Pulmonary Arteries Without IV Contrast Noncontrast MRA sequences alone for PE have been reported but remain investigational [43]. There is limited literature to support the use of noncontrast MRA of the pulmonary arteries for the evaluation of PE [24,34]. US Duplex Doppler Lower Extremity Compression US may be useful for patients who do not have a high likelihood of PE, particularly if the patient has symptoms of extremity DVT. Compression US with Doppler flow studies are used to evaluate for peripheral DVT. US studies include duplex Doppler with leg compression and continuous-wave Doppler [45,46]. The presence of DVT does not indicate the presence of PE, but it increases the likelihood. A negative extremity US study does not exclude PE, although it significantly decreases its likelihood [47-49]. V/Q Scan Lung The use of V/Q scans has considerably diminished with the widespread use of CTPA. Imaging protocols have evolved [10,58,59], and in some cases, perfusion imaging alone can be performed. The high negative predictive value of a normal V/Q scan has been confirmed by several studies, including a large outcome study [60]. Among the weaknesses of V/Q scanning are the high proportion of nondiagnostic results and the inability to provide alternative diagnosis [1,58]. Abnormal regional lung perfusion may suggest the diagnosis of PE, but it is not specific. Findings require correlation with ventilation studies or other imaging. Investigators have studied SPECT to improve the sensitivity and specificity of V/Q scintigraphy [61].
Suspected Pulmonary Embolism PCAs. This invasive procedure has an estimated morbidity and mortality of 3.5% to 6% and 0.2% to 0.5%, respectively [32,33]. MRA Pulmonary Arteries Without and With IV Contrast MRA can identify emboli in the central and segmental pulmonary arteries [34-37] among patients with low or intermediate probability with positive D-dimer [38]. However, limitations were identified by the PIOPED III trial Suspected Pulmonary Embolism MRA Pulmonary Arteries Without IV Contrast Noncontrast MRA sequences alone for PE have been reported but remain investigational [43]. There is limited literature to support the use of noncontrast MRA of the pulmonary arteries for the evaluation of PE [24,34]. US Duplex Doppler Lower Extremity Compression US may be useful for patients who do not have a high likelihood of PE, particularly if the patient has symptoms of extremity DVT. Compression US with Doppler flow studies are used to evaluate for peripheral DVT. US studies include duplex Doppler with leg compression and continuous-wave Doppler [45,46]. The presence of DVT does not indicate the presence of PE, but it increases the likelihood. A negative extremity US study does not exclude PE, although it significantly decreases its likelihood [47-49]. V/Q Scan Lung The use of V/Q scans has considerably diminished with the widespread use of CTPA. Imaging protocols have evolved [10,58,59], and in some cases, perfusion imaging alone can be performed. The high negative predictive value of a normal V/Q scan has been confirmed by several studies, including a large outcome study [60]. Among the weaknesses of V/Q scanning are the high proportion of nondiagnostic results and the inability to provide alternative diagnosis [1,58]. Abnormal regional lung perfusion may suggest the diagnosis of PE, but it is not specific. Findings require correlation with ventilation studies or other imaging. Investigators have studied SPECT to improve the sensitivity and specificity of V/Q scintigraphy [61].