Objective: The study is to assess the accuracy and reliability of three-dimensional simulated magnetic resonance imaging with silicone-excitation SPACE (sampling perfection with application optimized contrast using different flip angle evolutions) sequence for estimating implant volume. Methods: (1) MRI examinations of 10 silicone implants (Wuhan Tongji Hospital from October 2018 to December 2018) were performed with T2, H₂O-excitation SPACE sequence (T2-spc-H₂O) and silicone-excitation SPACE sequence (T2-spc-Silicone) to find the most accurate method to estimate implant volume by ITK-SNAP. The effect of implant deformation and slice thickness of T2-spc-Silicone on volume measurement were investigated. (2) 13 normal patients and 6 patients with implant complications (Wuhan Tongji Hospital from March 2017 to May 2019) were enrolled for testing the accuracy and reliability of T2-spc-Silicone for volume measurement in vivo. The data were analyzed using Prism 8.0 software. The paired student t-test was used to compare the difference of two groups. One-way ANOVA was used to compare the difference of multiple groups. P<0.05 was considered statistically significant. Results: The absolute volume differences of T2, T2-spc-H₂O, T2-spc-Silicone were (42.19±2.31) ml, (23.27±1.55) ml and (6.28±1.22) ml. The absolute volume differences of T2-spc-Silicone group was significantly less than T2-spc-H₂O and T2 group in vitro(F=195.3, P<0.001). No significant difference(F=1.36, P=0.22)was shown between the normality group and the deformation group for estimating the volume of implants with the slice thickness of SPACE increased from 0.5 mm×0.5 mm×0.5 mm to 5.0 mm×5.0 mm×5.0 mm. Besides, the slices thickness of SPACE from 0.5 mm×0.5 mm×0.5 mm to 5.0 mm×5.0 mm×5.0 mm did not significantly affect the accuracy of volume measurement of the implants in deformation state(F=1.22, P=0.29). The measurement error of SPACE was (8.82±0.99) ml in normal patients. Moreover, there was no significant difference between measured volume[(226.4±12.76)ml] and actual volume of implants[(225.9±11.94) ml](t=0.31, P=0.76)in patients with implant complications. The result showed excellent intraobserver reliability (ICC=0.997) and internal consistency ranged from 0.986 to 0.997 (P<0.001). Conclusions The method to measure implant volume by silicone-excitation SPACE sequence had desirable accuracy and reliability. The deformation of the implant and the slice thickness of the SPACE sequence did not exhibit a significant effect on the accuracy of volume measurement.