Cloverleaf Sign in Pelvic Magnetic Resonance Imaging for Deep Infiltrating Endometriosis: Association With Longer Operation Times, Greater Blood Loss, and Higher Rates of Bowel Resection.

Härmä, Kirsi Hannele; Binda, Aleksandra; Ith, Michael; Pöllinger, Alexander; Siegenthaler, Franziska; Heverhagen, Johannes; Imboden, Sara; Mueller, Michael (2020). Cloverleaf Sign in Pelvic Magnetic Resonance Imaging for Deep Infiltrating Endometriosis: Association With Longer Operation Times, Greater Blood Loss, and Higher Rates of Bowel Resection. Investigative radiology, 55(1), pp. 53-59. Wolters Kluwer Health 10.1097/RLI.0000000000000612

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OBJECTIVES

The aim of this study was to evaluate the significance of a new imaging sign, the "cloverleaf sign," in diagnosing deep infiltrating endometriosis (DIE) with magnetic resonance imaging (MRI) in concordance to intraoperative findings.

MATERIALS AND METHODS

This retrospective study included 103 patients operated during the January 2016 to June 2018 period with preoperative 1.5 T and 3 T MRI, with or without vaginal and rectal gel filling. Magnetic resonance imaging scans were read blinded to intraoperative findings by a specialized gynecologic radiologist and a junior radiologist, and then compared with intraoperative findings by looking at the operation report, postoperative diagnosis, and intraoperative images and videos by an experienced gynecologist surgeon specialized in endometriosis surgery. All endometriosis lesions were confirmed by pathology. The "cloverleaf sign" was defined as a cloverleaf-like figure in imaging morphology; the "leaves" formed by at least 3 different organs come together in the center of the figure formed by constrictive adhesions including T2-weighted (T2W) hypointense DIE. Operation times, intraoperative blood loss, and the frequency of DIE and bowel resections were analyzed in cloverleaf and noncloverleaf groups. The 2-sample Wilcoxon rank-sum (Mann-Whitney U) test and multivariate analysis of variance were used to calculate the significance of an overall impact of cloverleaf sign on operation time, blood loss, and the amount of the bowel resection rate. P < 0.05 was considered statistically significant.

RESULTS

The prevalence of DIE in the study population was 79.6%. A total of 11.5% of the patients had no endometriosis, 32.6% had rASRM I and II, and 55.9% had rASRM III and IV. Forty-six patients (45%) had received rectal and vaginal gel opacification before scanning, 57 (55%) did not. A cloverleaf sign on MRI was detected in 34 patients (15 in gel filling and 19 in nonfilling group). The interreader agreement was almost perfect 0.91 (κ). The median operation time in the cloverleaf group was 248 minutes (interquartile range [IQR], 165-330) compared with 145 minutes in the noncloverleaf group (IQR, 90-210), that is, significantly higher (P < 0.001). Intraoperative blood loss was also significantly higher in the conglomerate group (125 vs 50 mL; IQR, 100-300 vs 50-100; P < 0.001). Of the bowel resections in our study population, 41% (14/34) were performed on patients with a cloverleaf sign in the MRI, compared with 13% (9/69) in patients without the cloverleaf sign.

CONCLUSIONS

The "cloverleaf" MRI sign was associated with significantly longer operation time, increased intraoperative blood loss, and higher rates of bowel resection in DIE patients.

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