A comparative study of two pelvimetry methods: 3D models based on CT and MRI.

Introduction And Hypothesis: To compare 3D models based on magnetic resonance imaging (MRI) and 3D models based on computed tomography (CT) in pelvimetry.

Methods: A retrospective analysis of 141 patients who underwent both pelvic 3D MRI and 3D CT pelvimetry for gynecological diseases from December 2009 to October 2020 was performed. The two pelvimetry methods were compared by paired Student's t test, Pearson's correlation coefficient, Bland-Altman analysis and intraclass correlation coefficient (ICC).

Results: The differences between methods for each diameter were statistically significant, except for those of the posterior sagittal diameter of the pelvic inlet (t:-0.71, P = 0.5) and the anteroposterior pelvic outlet diameter (t:0.02, P = 0.98). 3D MRI and 3D CT pelvimetry strongly correlated with each other (r: min 0.7, max: 0.96, P < 0.01). The Bland-Altman results indicate that the difference points of each pelvic diameter line greater than 95 % are within the 95 % limits of agreement. The ICC was good to very good for all pelvimetric measurements using either MRI-3D (ICC: 0.64-0.98) or CT-3D (ICC: 0.72-0.98) between the two readers.

Conclusions: 3D MRI and 3D CT pelvimetry have good agreement and reproducibility, indicating that 3D MRI is reliable for pelvimetry.