Department of Bioengineering, University of Pittsburgh, 406 Benedum Hall, 3700 O'Hara Street, Pittsburgh, PA 15260, United States.
Cleveland Clinic Foundation, Cleveland, OH, United States.
Comput Methods Programs Biomed. 2021 Sep;208:106175. doi: 10.1016/j.cmpb.2021.106175. Epub 2021 May 16.
Pelvic organ prolapse (POP), the herniation of the pelvic organs toward the vaginal opening, is a common pelvic floor disorder (PFD) whose etiology is poorly understood. Traditional methods for evaluating POP are often constrained to external vaginal examination, limited to 2D, or have poor reproducibility. We propose a reliable 3D anatomic coordinate system for standardized 3D assessment of pelvic anatomy using magnetic resonance imaging (MRI).
The novel 3D anatomic reference system is based on six bony landmarks of the pelvis manually identified in MRI: the ischial spines and the superior and inferior pubic points of the left and right pubic symphysis. The origin of this system is defined as the midpoint of the ischial spines. The reproducibility and applicability of the pelvic coordinate system were evaluated by (1) implementing it in a new method to quantify vaginal position and axis (angulation) in 3D space from MRI segmentations of the vagina and (2) computing the intraclass correlation (ICC) on coordinate system and vaginal measures. The MRI analysis was performed by four non-medically trained observers on five pelvic MRI datasets on approximately five separate occasions.
Overall, all bony landmarks had excellent intra-observer reliability and inter-observer reliability (ICC>0.90); intra-observer reliability was moderate-to-good among the vaginal position parameters (0.5<ICC≤0.90) and moderate for the vaginal axis angles (0.50<ICC≤0.75); inter-observer reliability was moderate in the vaginal position coordinates and vaginal axis measures. On average, within-observer differences in the vaginal position and angle measures relative to the overall mean were <1 mm and <1°, respectively.
The proposed anatomic coordinate system and vaginal analysis approach allow quantitative assessment of pelvic anatomy that is robust to the experience level of the observer. The application of these methods in radiographic studies will give new insight into the underlying anatomic changes involved in the pathogenesis of POP and other PFDs and help better understand their etiology.
盆腔器官脱垂（POP）是一种常见的盆底功能障碍性疾病（PFD），其病因尚不清楚。传统的 POP 评估方法通常仅限于外部阴道检查，且限制在 2D 层面，或重复性较差。本研究旨在提出一种可靠的 3D 解剖坐标系，以利用磁共振成像（MRI）对盆腔解剖结构进行标准化 3D 评估。
该新的 3D 解剖参考系统基于 MRI 中手动识别的骨盆 6 个骨性标志：坐骨棘和左右耻骨联合的上、下耻骨点。该系统的原点定义为坐骨棘的中点。通过（1）在一种新的方法中实施该系统，以量化 3D 空间中阴道的位置和轴线（角度），以及（2）计算坐标系和阴道测量的组内相关系数（ICC），评估该骨盆坐标系的可重复性和适用性。该 MRI 分析由 4 名非医学专业的观察者在大约 5 个不同时间点对 5 个骨盆 MRI 数据集进行。
总体而言，所有骨性标志均具有极好的观察者内和观察者间可靠性（ICC＞0.90）；阴道位置参数的观察者内可靠性为中度至极好（0.5＜ICC≤0.90），阴道轴线角度的观察者内可靠性为中度（0.50＜ICC≤0.75）；阴道位置坐标和阴道轴线测量的观察者间可靠性为中度。平均而言，与总体平均值相比，阴道位置和角度测量的观察者内差异小于 1mm 和 1°。
所提出的解剖坐标系和阴道分析方法可对骨盆解剖结构进行定量评估，且对观察者的经验水平具有稳健性。这些方法在影像学研究中的应用将为 POP 和其他 PFD 的发病机制所涉及的潜在解剖变化提供新的见解，并有助于更好地了解其病因。
