Can three-dimensional pelvimetry using low-dose stereoradiography replace low-dose CT pelvimetry?

Purpose: To evaluate the reliability of pelvimetric measurements performed using stereoradiographic imaging (SRI), and to assess maternal and fetal radiation doses compared to low-dose computer tomography (CT) pelvimetry. Materials and methods: Thirty-five pregnant women (mean age, 29.6 +/- 5.5 [SD] years; range: 20-41 years) were prospectively included. All women underwent simultaneous frontal and lateral low-dose SRI and low-dose CT examination of the pelvis. Pelvimetry measurements were obtained from both examinations and radiation doses obtained with the two techniques were evaluation; compared. Results: SRI-CT correlation (Pearson coefficient correlation [r]; mean bias [mb]) was strong for transverse inlet diameter (r =0.92; mb= -0.09 cm), anteroposterior diameter of the pelvic inlet (r = 0.92; mb = 0.47 cm), maximal transverse diameter (r = 0.9; mb =0.21 cm), sacrum length (r = 0.9; mb = 0.09 cm). Correlation was good. Correlation was good for the sacrum depth r= 0.75; mb =0.06 cm) and Magnin's index (r =0.7; mb = 0.5 cm). Correlation was moderate for anteroposterior diameter of pelvic outlet (r = 0.6; mb =0.52 cm). The fetal dose was 13.1 times lower using SRI (87 +/- 26 mu Gy) than CT (1140 +/- 220 mu Gy P < 0 .0001). The effective maternal dose was 3.1 times lower using SRI (97 +/- 21 p.mu Sv) than CT (310 +/- 60 mu Sv; P<0.0001). Conclusion: Pelvic inlet measurements using SRI are reliable. Compared to CT pelvimetry, SRI leads to a significant decrease in fetal and maternal radiation doses. These findings should prompt physicians to use SRI as the first-line approach for pelvimetry. (C) 2018 Societe francaise de radiologie. Published by Elsevier Masson SAS. All rights reserved.