Publication Articles

Why Guidelines are Important? Inter observer variability in assessing MRI signs of Endometriosis between reader following ESUR guidelines versus reader using prior domain knowledge

Oral Presentation at the European Congress of Radiology, Vienna, 2019

Purpose

To assess the interobserver variability in identifying the MRI signs of endometriosis as described by European society of urogenital radiology.

Methods and Materials

This retrospective study included 77 randomly selected cases of endometriosis diagnosed on MRI. The cases were pulled from PACS, anonymized and assigned to two radiologists with 16 years and 11 years of experience in body imaging. The radiologists identified the presence or absence of following signs in each case: Retroflexion of uterus, torus uterinus involvement, Uterosacral ligament thickening, tethering of rectum, ovaries adherent to uterus, posterior position of ovaries, cluster Of haemorrhagic cysts in ovaries, thickened round ligament, uterus and ovaries posterior to inter-ischial line, T2 Shading, restricted diffusion, hematosalpinx, vaginal vault pulled-up, bladder involvement and superficial peritoneal implants.Radiologist 1 followed the definitions of the ESUR guidelines whereas Radiologist 2 assigned the labels based on prior domain knowledge. Interobserver variability was assessed (Fleiss bounds) via the Krippendorff's alpha coefficient corrected for chance.

Results

The interobserver variability ranged from ‘fair to good’ (Fleiss bounds, 0.41-0.75) in 9 labels (retroflexion, ovaries adherent to uterus, posterior position of ovaries, haemorrhagic cluster cyst in ovaries, T2-shading, hematosalpinx, pulling up of vaginal vault, bladder involvement, superficial peritoneal implants). Five labels (torus uterinus involvement, uterosacral ligament thickening, tethering of rectum, thickened round ligament, uterus and ovaries posterior to inter-ischial line, restricted diffusion) were deemed ‘poor’ (<0.40)

Conclusion

We identified the MRI signs of endometriosis having high inter-observer variability. There is scope for improvement in the agreement if the guidelines are followed universally