Diagnostic testing Screening of outpatients with D-dimer testing if pre-test probability is low or of intermediate probability If pretest probability is likely or if D-dimer result is elevated, CT angiography, or if renal insufficiency is present or when CT contrast is contraindicated, with ventilation / perfusion (V / Q) scanning Sometimes ultrasonography of the legs or arms (to confirm DVT when lung imaging is delayed or prohibitive) There is no universally accepted algorithm for the approach to suspected acute pulmonary embolism.