Radionuclide imaging of acute pulmonary embolism.

From the prospective and outcome-based studies that have been carried out in the past few years, the following conclusions regarding the diagnostic evaluation of patients with suspected PE can be made: 1. A normal V/Q scan interpretation excludes the diagnosis of clinically significant PE. 2. Patients with a very-low- or low-probability V/Q scan interpretation and a low clinical likelihood of PE do not require angiography or anticoagulation. 3. Patients with a very-low- or low-probability V/Q scan interpretation, an intermediate or high clinical likelihood of PE, and negative serial noninvasive venous studies of the lower extremities do not require anticoagulation or angiography. If serial noninvasive venous studies of the lower extremities are positive, patients should be treated. 4. Clinically stable patients with an intermediate-probability V/Q scan interpretation require noninvasive venous studies of the legs and, if negative, require CT angiography or pulmonary angiography for a definite diagnosis. 5. Clinically stable patients with a high-probability V/Q scan interpretation and a high clinical likelihood of PE require treatment and need no further diagnostic tests to confirm the diagnosis. 6. Clinically stable patients with a high-probability V/Q scan interpretation and a low or intermediate clinical likelihood of PE require noninvasive venous studies of the legs and, if negative, often require CT angiography or pulmonary CT for a definitive diagnosis.