Computerized tomographic pulmonary angiography versus ventilation perfusion lung scanning for the diagnosis of...

The purpose of this review is to focus on recent research that has addressed the relative merits of computed tomographic pulmonary angiography (CTPA) and ventilation perfusion (V/Q) scanning for the diagnosis of pulmonary embolism.

Computed tomographic pulmonary angiography is the most sensitive test for the diagnosis of pulmonary embolism and its use has been associated with a rising incidence of the condition. Diagnostic algorithms using either CTPA or V/Q scanning have proven to be comparably safe to exclude the diagnosis of pulmonary embolism. Negative multidetector CTPA study results essentially ruled out the diagnosis of pulmonary embolism without the need to routinely exclude the presence of deep vein thrombosis. Use of multidetector CTPA was associated with significant radiation exposure that potentially increases risk of secondary malignancies. This is particularly a concern for young women given the risk of breast cancer. Single photon emission tomography (SPECT) V/Q and modified diagnostic criteria for V/Q scan interpretation increased their diagnostic accuracy compared with V/Q scanning and offer nuclear medicine modalities that are alternatives to CTPA in at least some patients with suspected pulmonary embolism at a fraction of the risk of radiation exposure. Excluding low risk patients for pulmonary embolism as defined by clinical scoring systems and D-dimer testing would enhance the yield of diagnostic testing.

Computed tomographic pulmonary angiography is the most reliable test for diagnosis of pulmonary embolism. However, diagnostic algorithms using V/Q scanning are safe and may be preferred in some patient populations.