A systematic review of clinical studies on dynamic magnetic resonance imaging of pelvic organ prolapse: the use of reference lines and anatomical landmarks

Abstract

Introduction and hypothesis The aim of our study was to provide a systematic literature review of clinical studies on pelvic organ prolapse staging with use of dynamic magnetic resonance (MR) imaging. Methods The databases EMBASE and PubMed were searched. Clinical studies were included in case they compared pelvic organ prolapse stages as assessed on dynamic MR imaging (using a reference line) with a standardized method of clinical prolapse staging. Results Ten studies were included, which made use of seven different reference lines in relation to a wide variety of anatomical landmarks. Conclusions Only few studies have compared pelvic organ prolapse stages as assessed by dynamic MR imaging and clinical examination in a standardized manner. The available evidence suggests that prolapse assessment on dynamic MR imaging may be useful in the posterior compartment, but clinical assessment and dynamic MR imaging seem interchangeable in the anterior and central compartment.

Standardization of dynamic magnetic resonance imaging measurements of pelvic organ prolapse: can the PICS line help?

“…MRI is particularly indicated in women with multi-compartment POP and in those who had undergone previous repair, as imaging can reveal more extensive prolapse than physical examination alone with detection rates similar to other conventional fluoroscopic and ultrasound methods [1,3,4]. Staging of POP using MRI has also been suggested by measuring the perpendicular distance between several reference points and lines in each compartment at rest and after straining [1][2][3][4][5]. The two most commonly used lines are one connecting the inferior aspect of the pubic symphysis to the last coccygeal joint, the pubococcygeal line (PCL), and one extending caudally along the long axis of the symphysis pubis, the midpubic line (MPL).…”

“…"MPL/hymenal line" and "PCL/sacrococcygeal inferior pubic point line" [2]. Although the MPL corresponds anatomically to the level of the hymen on cadaveric dissection, the landmark used for clinical staging of POP, the reliability of MRI using the MPL versus clinical findings in women with POP was lower than that of the PCL in most reports [1,2].It is obvious that we lack a proper validation system for interpreting MRI measurements of POP and we urgently need to reach a consensus on a more standardized and scientifically robust MRI protocol for examination of the pelvis. Betschart et al review this topic further in a seminal Clinical Opinion…”

“…The primary objective was to better select candidates for surgical intervention and choose the appropriate procedure in order to reduce recurrences by allowing accurate identification and objective measurement of prolapse and simultaneous topographic assessment of the pelvis at rest and straining [1][2][3][4][5]. MRI is particularly indicated in women with multi-compartment POP and in those who had undergone previous repair, as imaging can reveal more extensive prolapse than physical examination alone with detection rates similar to other conventional fluoroscopic and ultrasound methods [1,3,4].…”

“…Most importantly, so far, there has been no standardized technique for performing MRI examination of the pelvis. Imaging protocols vary according to patient positioning, filling media, pelvic organ opacification, patient maneuvers (i.e., rest, Kegel, Valsalva, evacuation) and MRI sequences and planes [1][2][3][4][5]. Most of the available imaging systems are unable to demonstrate the full extent of POP because patients are examined in a supine position promoting current efforts to image patients in the sitting and upright position using open-magnet MRI units [1,[3][4][5].…”

“…The intra-and inter-observer reliability of most MRI measurements is, however, rarely described in POP studies [2]. Furthermore, the reference line used for MRI interpretation of POP is not consistent in all studies as this is often based on radiologist experience and referring physician preference [1,5].…”