Dose and image quality at CT pulmonary angiography-comparison of first and second generation dual-energy CT and 64-slice CT

Objective To compare dose and image quality of 64-slice, first and second generation dual-energy CT (DECT) for CT pulmonary angiography (CTPA). Methods Totally 120 patients, 30 in each group, underwent CTPA on a first generation (group 1: single-energy, 120 kV/145 mAs; group 2: DE, 140/80 kV, 70/350 mAs) or second generation dual-source DECT device (group 3: DE, 100/Sn140 kV, 120/102 mAs; group 4: DE, 80/Sn140 kV, 202/86 mAs). CTDIvol, DLP, background noise (BN), thorax diameter and attenuation in the pulmonary trunk were compared. Results Thorax diameter and attenuation in the pulmonary trunk did not differ significantly (p > 0.4 and > 0.19) between the groups. Mean CTDIvol and DLP were significantly lower (p < 0.003) in group 4 (6.2 +/- 1.6 mGy/170 +/- 41 mGycm) compared to group 1 (8.5 +/- 2.6 mGy/235 +/- 117 mGycm), group 2 (9.2 +/- 3.3 mGy/224 +/- 122 mGycm) and group 3 (8.7 +/- 2.8 mGy/246 +/- 86 mGycm). BN was significantly lower (p < 0.0001) in group 4 (12 +/- 3 HU) and group 1 (13 +/- 6 HU) compared to group 3 and 2 (16 +/- 6 HU and 23 +/- 9). Conclusion The use of second generation DECT in 80/Sn140 kV configuration allows for significant dose reduction with image quality similar to 120 kV CTPA.