Image registration to assist the diagnosis of pelvic floor disorder in MR defecography

Over the last decades, the interest in the use of the defecography for the investigation of defecation problems and pelvic floor disorders has increased. The MR defecography assists in the diagnosis of pelvic floor weakening, fecal incontinence, painful defection and genital prolapse. To identify an abnormal morphological variation of the structures relevant for the diagnosis, the radiologist derives several static measures at different moments and at different maneuvers during the exam. However, there is a poor agreement between independent observers for the measurement of the anorectal angle, which is a critical parameter for the interpretation of the defecography. With the aim of reducing the inter-observer variability and assisting the radiologist in the interpretation of the MR defecography for the diagnosis of fecal incontinence, we propose calculating dynamic changes of anorectal junction during the defecation activity. To that end we propose to propagate, automatically, the location of pre-defined landmarks throughout the frames of the MR defecography, for each maneuver, via image registration based on variational model. The analysis of the results shows that our proposal was well succeeded in the propagation of the initial landmarks and to calculate the dynamic changes during each maneuver.