Ventilation perfusion (VQ) scanning remains an alternative method of imaging for PE, particularly in individuals without pre-existing lung disease in whom the incidence of nondiagnostic results is decreased.30 It has the advantage over CTPA of not requiring contrast exposure, and therefore is the investigation of choice in patients with renal impairment. Breast radiation exposure is also substantially reduced with VQ scanning in comparison to CTPA, and therefore it should be considered as a first line investigation for PE in women of reproductive age. A normal VQ scan can be used to exclude PE, while a high probability scan justifies anticoagulation. All other results are associated with an intermediate probability of PE (10–40%) and further imaging, normally CTPA, is therefore required .
To its credit this review makes no evidential claims as to which imaging modality is best. It merely says:
Computerized tomographic pulmonary angiography (CTPA) has become the most widely used radiological investigation for suspected PE.
All these recent reviews are remarkably consistent in their recommendation that the decision for imaging should be made on an initial pre-test assessment tool combined with D dimer testing.