The primary objective of this study was to evaluate the effectiveness of high-resolution organ-axial T2WI in increasing the accuracy and reliability of the FIGO classification of uterine fibroids. Organ-axial T2WI was more accurate than body-axial T2WI in the FIGO classification of uterine fibroids. In addition, organ-axial T2WI exhibited a high level of interobserver consistency and greater accuracy with surgical findings in the FIGO classification of uterine fibroids, significantly outperforming traditional body-axial T2WI. These findings suggest that organ-axial T2W imaging can be a reliable and consistent method for evaluating uterine fibroids, potentially improving diagnostic precision and clinical outcomes.

The FIGO classification system contributes to categorizing lesions, guiding patient management, and providing prognostic information [6, 10, 17]. The position of the uterus in the pelvis is variable, and adjusting the acquisition plane could overcome this issue. Organ-axial T2WI, which angles both the sagittal and the coronal planes, creates a “true axial oblique” plane that is correctly positioned along the true axis of the uterus [18, 19]. Our study revealed that the organ-axial T2WI protocol performed better than the body-axial T2WI protocol did in terms of the FIGO classification. These findings suggest that organ-axial T2WI may be superior to body-axial T2WI for fibroid classification. While there are no studies on the application of organ-axial images in terms of fibroids, our study confirmed that this technique increased the reliability and accuracy of FIGO classification, which is similar to that of endometrial cancer and cervical cancer [20, 21]. These results are consistent with the ESUR guidelines, which support the use of organ-axial T2WI [22].

In this study, the interobserver agreement for determining the FIGO classification of fibroids via organ-axial MRI achieved a kappa value of 0.877, indicating a high level of consistency among different observers. This finding may be because, in body-axial T2WI, partial volume effects result in discrepancies in the results, whereas organ-axial T2WI, which is determined along the true axis of the uterus, avoids the impact of partial volume effects, thereby generating greater interobserver agreement [12, 20]. Additionally, our study results confirmed that organ-axial T2WI has greater consistency with the operation. Furthermore, the organ-axial T2WI (k = 0.932) is more consistent with the operation than the body-axial T2WI (k = 0.591), which is consistent with previous literature, indicating that the consistency between readers regarding the FIGO classification of fibroids on the basis of body-axial T2WI is low and has poorer conformity with operation identification [14]. These findings suggest that organ-axial T2WI has potential value for fibroid classification and may be beneficial in surgical planning.

An understanding of the relationships among indices of uterine cavity deformation (such as compression pulse width, compression depth, and compression angle) is pivotal for a more accurate preoperative assessment of the uterine fibroid FIGO classification and surgical approach [23]. This understanding is crucial for guiding clinical decision-making and formulating treatment plans, facilitating optimized surgical strategies and improving patient outcomes. According to previous studies, distortion of the uterine cavity is typically attributed to submucosal fibroids with FIGO types 0, 1 and 2 and to intramural fibroids with FIGO types 2–5 [6, 12, 24]. Conversely, intramural fibroids, with FIGO types 3, 4, and 5; and subserosal fibroids, with FIGO types 6 and 7 [6, 12, 24], do not distort the uterine cavity. Nonetheless, our research revealed that patients with FIGO types 3–6 had different proportions of patients with signs of uterine cavity compression. In cases of types 0–6 and 2–5, which caused uterine cavity deformation, the compression angle was linearly correlated with the FIGO classification. This finding indicates that the deformation of the uterine cavity gradually transitions from tongue-like protruding to pushing from type 0 to types 6 and 2–5. Furthermore, fibroids cause physical compression, and deformation of the uterine cavity is an important mechanism related to infertility [24]. Our findings also imply that an increased number of fibroids may pose a potential risk of subfertility, requiring intervention to restore uterine cavity shape.

This study had several limitations. First, this study was conducted at a single center and multiple institutions, and a large sample size cohort is necessary to further validate the results of our present study. Second, due to the constraints of our study design and sample size, we were unable to conduct a detailed investigation into the relationship between uterine fibroids and infertility. This limitation highlights the need for further research with larger, more representative cohorts to better understand this complex relationship. Third, the two-week training program at study onset may have introduced bias, which we acknowledge as a limitation. To address this shortcoming, we implemented a standardized training protocol and a blinded assessment to minimize its impact. Future studies should expand the training period and sample size to further validate our findings. Fourth, organ-axial T2WI increases the additional scanning time, whereas 3D T2WI can help reduce the scanning time. In future studies, we will consider 3D scanning as a potential option, provided that image resolution is maintained.