The rectal vaginal opacification with water and the antiperistaltic agent in magnetic resonance scanning of the intestinal endometriosis

The diagnosis of deep intestinal endometriosis is mandatory to plan treatment and for follow-up; however, there is no consensus worldwide in the use of rectal/ vaginal opacification and anti-peristaltic agents for magnetic resonance imaging (MRI) scanning, being defined as an option for the examination. The transvaginal ultrasound images of previous MRI with the standard protocol, and recent MRI in our institution with rectal/vaginal opacification with water and the anti-peristaltic agent are presented in four cases for comparison, respectively. The technique in our institution seems to be more effective than routine pelvic MRI scans in the intestinal endometriosis.


Introduction
Deep infiltrating endometriosis (DIE) is involvement of the retrocervical septum, rectovaginal septum, uterosacral ligaments, vaginal fornix, and bladder (1) , and intestinal involvement occurs in 12-37% of patients with endometriosis (2) . Transvaginal ultrasound (TVUS) is the first-line method and magnetic resonance imaging (MRI) should be considered as a second-line technique after TVUS (3) . However, the MRI diagnosis of DIE is a dilemma in radiology departments because most MRI scans with suspicion of DIE are negative in spite of either an intestinal endometriotic nodule in TVUS or the clinical history being in favor of DIE. There is no universally accepted protocol for MRI in endometriosis for the use of vaginal and/or rectal opacification (RVO) (3). In the presented cases, which were initially diagnosed using TVUS as intestinal endometriosis, the findings of MRI scans with and without RVO with water and anti-peristaltic agent use are presented.

Case Report
The 53 patients with TVUS findings in favor of deep pelvic endometriosis were collected between 2016 and 2018. The criterion for patient selection was the presence of at least three of the following TVUS findings: (1)

restriction of uterus mobility
The rectal vaginal opacification with water and the antiperistaltic agent in magnetic resonance scanning of the intestinal endometriosis or pain with probe compression; (2) kissing ovaries; (3) unilateral or bilateral ovarian endometrioma; (4) intestinal wall thickening; and (5) intestinal endometriotic nodule either as the mushroom cap sign or the Indian headdress sign (4) . Twenty-nine patients who were examined using MRI due to TVUS findings and the previous MRI scans of 28 patients, performed either in our center or an external tertiary care hospital or in a private hospital, were re-examined retrospectively. All of the MRI scans were reported to be normal concerning DIE in spite of clinical information or TVUS findings. Four of the 28 patients with endometriosis with intestinal involvement considering the TVUS findings were re-scanned using MRI prospectively due to serious clinical symptoms. All of the MRI re-scans were performed according to the European Society of Urogenital Radiology DIE guideline (3) . Written informed consent was obtained from all subjects, according to the World Medical Association Declaration of Helsinki, revised in 2000, Edinburgh. The histories and the clinical information of the 4 patients are obtained as suggested by the IDEA group (4) and these were noted for each patient respectively (Table 1) Technique A 1.5 Tesla Magnetom_Essenza MRI system (Siemens AG Wittelsbacherplatz 2 80333 Muenchen Germany) was used for the MRI re-scans anda Toshiba Applio 500 ultrasound system was used for transvaginal examinations (TUS-A500, Toshiba Medical Systems, Europe BV, Zilverstraat 1, 2718 RP, Zoetermeer, The Netherlands). The patients were informed to use a rectal enema 12 and 2 hours before the MRI exams  Figure 1).

Magnetic Resonance Imaging Sequences
2D T2W sagittal/axial/coronal, 2D T1W sagittal/axial with and without fat saturation, T1W Dixon sagittal, and diffusionweighted sequences were performed. Gadolinium is not used for intravenous or in saline solution for contrast opacification. If there was an interval more than 3 months between the previous and the present MRI scan, initial T2W sagittal images were obtained just before applying the RVO with water and the APA in order to exclude recent nodule growth. The findings in TVUS, the previous MRI scans, and the re-scanned MRI examinations are presented as images, respectively. The endometriotic nodules in the bowel wall are demonstrated clearly in all patient re-scans, which had been reported as normal previously ( Figure  2-6).

Discussion
The MRI examinations are crucial for the proper diagnosis and for the demonstration of the extent of the lesions  On T1W sequences, the lesions are hyperintense in early phases due to bleeding and hypointense in the chronic phases due to fibrosis (6) . Mostly the lesions are in the chronic phase, which is why the bright intestinal lumen is mandatory in order to visualize the fibrotic nodules, especially for inexperienced examiners. However, there is no consensus for RVO with water and APA use, which is published to be an option in the medical literature (3,7) . In daily practice, MRI scans are performed without these options. Here, it is clearly seen that MRI with RVO with water and APA use is more appropriate than routine MRI scans for intestinal DIE. Administration of the optional procedures requires an extra 10 to 15 minutes, so it might be not preferred in some radiology departments. In Turkey, public hospitals are autonomized to allow them to outsource some medical services such as diagnostic imaging, (8) and the less time required for MRI scanning means more income for the out-source services. Therefore, the use of the optional technique should be restricted by choosing patients with DIE before the MRI scans using TVUS. In our experience, the   There is regular thickening in the muscular propria diagnosis of intestinal involvement in endometriosis using MRI needs RVO with water and APA use; therefore, it should not be an option in MRI scans as in the guidelines, but an obligation in patients with endometriosis with intestinal involvement in order to increase the detectability.

Ethics
Informed Consent: Written informed consent was obtained from all subjects. Peer-review: Externally peer-reviewed.

Authorship Contributions
Surgical