The objective of this study is to investigate the feasibility of prospectively respiratory-triggered CT pulmonary angiography (CTPA) for detection of pulmonary embolism (PE) in a porcine model. A free-breathing respiratory-triggered multislice CTPA (120 kV, 140 mAs(eff), 2.5-mm slice thickness) and two CTPA in breath-hold technique (120 kV, 140 mAs(eff.) and 250mAs(eff), 1-mm and 3-mm image reconstruction) were performed in six pigs with pulmonary embolism. Diagnostic accuracy was computed, and differences in detection rates between both techniques were assessed on a per-embolus basis with the Wilcoxon test. Thin-sliced 1-mm images, acquired with 250mAs(eff), served as the standard of reference. Respiratory-triggered CTPA reached high diagnostic accuracy in detection of lobar and segmental PE equal to the results with the breath-hold technique (p > 0.05). For detection of subsegmental emboli, standard breath-hold techniques performed significantly better than respiratory-gated CTPA (sensitivity, 68.3% versus 24.4%; p <0.05). Free-breathing respiratory-triggered CTPA is feasible for detection of lobar and segmental PE, with diagnostic accuracy equivalent to that of a standard CTPA in breath-hold. Although this technique is not recommended for assessment of emboli in the subsegmental vasculature, prospective respiratory-triggered CTPA may be of added value in patients who cannot hold their breath appropriately for CTPA scanning.
The objective of this study is to investigate the feasibility of prospectively respiratory-triggered CT pulmonary angiography (CTPA) for detection of pulmonary embolism (PE) in a porcine model. A free-breathing respiratory-triggered multislice CTPA (120 kV, 140 mAs(eff), 2.5-mm slice thickness) and two CTPA in breath-hold technique (120 kV, 140 mAs(eff.) and 250mAs(eff), 1-mm and 3-mm image reconstruction) were performed in six pigs with pulmonary embolism. Diagnostic accuracy was computed, and differences in detection rates between both techniques were assessed on a per-embolus basis with the Wilcoxon test. Thin-sliced 1-mm images, acquired with 250mAs(eff), served as the standard of reference. Respiratory-triggered CTPA reached high diagnostic accuracy in detection of lobar and segmental PE equal to the results with the breath-hold technique (p > 0.05). For detection of subsegmental emboli, standard breath-hold techniques performed significantly better than respiratory-gated CTPA (sensitivity, 68.3% versus 24.4%; p <0.05). Free-breathing respiratory-triggered CTPA is feasible for detection of lobar and segmental PE, with diagnostic accuracy equivalent to that of a standard CTPA in breath-hold. Although this technique is not recommended for assessment of emboli in the subsegmental vasculature, prospective respiratory-triggered CTPA may be of added value in patients who cannot hold their breath appropriately for CTPA scanning.