Challenges in the diagnosis of acute pulmonary embolism.

The state of the art of diagnostic evaluation of hemodynamically stable patients with suspected acute pulmonary embolism was reviewed. Diagnostic evaluation should begin with clinical assessment using a validated prediction rule in combination with measurement of D-dimer when appropriate. Imaging should follow only when necessary. Although with 4-slice computed tomography (CT) and 16-slice CT, the sensitivity for detection of pulmonary embolism was increased by combining CT angiography with CT venography, it is not known whether CT venography increases the sensitivity of 64-slice CT angiography. Methods to reduce the radiation exposure of CT venography include imaging only the proximal leg veins (excluding the pelvis) and obtaining discontinuous images. Compression ultrasound can be used instead. In young women, radiation of the breasts produces the greatest risk of radiation-induced cancer. It may be that scintigraphy is the imaging test of choice in such patients, but this pathway should be tested prospectively. A patient-specific approach to the diagnosis of pulmonary embolism can be taken safely in hemodynamically stable patients to increase efficiency and decrease cost and exposure to radiation.