CT pulmonary angiography: simultaneous low-pitch dualsource acquisition mode with 70kVp and 40ml of contrast medium and comparison with high-pitch spiral dual-source acquisition with automated tube potential selection

Objective: To assess the feasibility of a 70-kVp CT pulmonary angiography (CTPA) protocol using simultaneous dual-source (SimDS) acquisition mode with 40ml of contrast medium (CM) and comparison with a high-pitch spiral dual-source (SpiralDS) acquisition protocol with automated tube potential selection (ATPS). Methods: Following the introduction of a new 70-kVp/40-ml SimDS-CTPA protocol in December 2014 for all patients with a body mass index (BMI) below 35 kg m(-2), the first 35 patients were retrospectively included in this study and assigned to Group A (BMI: 2764kg m(-2), age: 66615 years). The last 35 patients with a BMI below 35 kg m(-2) who had received SpiralDS-CTPA with ATPS were included for comparison (Group B) (70 ml CM; BMI: 2764kg m(-2), age: 68616 years). Subjective image quality (image quality) was assessed by two radiologists (from 1, non-diagnostic, to 4, excellent). Signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), volumetric CT dose index (CTDIvol), dose-length product (DLP) and effective dose were assessed. Results: All examinations were of diagnostic image quality. Subjective image quality, SNR and CNR were comparable between Groups A and B (3.7 +/- 0.6 vs 3.76 +/- 0.5, 14.6 +/- 6.0 vs 13.9 +/- 3.7 and 12.4 +/- 5.7 vs 11.6 +/- 3.3, respectively; p > 0.05). CTDIvol, DLP and effective dose were significantly lower in Group A than in Group B (4.5 +/- 1.6 vs 7.5 +/- 2.1mGy, 143.3 +/- 44.8 vs 278.3 +/- 79.44mGy cm and 2.0 +/- 0.6 vs 3.9 +/- 1.1mSv, respectively; p, 0.05). Conclusion: 70-kVp SimDS-CTPA with 40ml of CM is feasible and provides diagnostic image quality, while radiation dose and CM can be reduced by almost 50% and 40%, respectively, compared with a SpiralDS-CTPA protocol with ATPS. Advances in knowledge: 70-kVp SimDS-CTPA with 40ml of CM is feasible in patients with a BMI up to 35kg m(-2) and can help reduce radiation exposure and CM in these patients.