Relationship between sphincter morphology on endoanal MRI and histopathological aspects of the external anal sphincter

Abstract

Atrophy of the external anal sphincter can be shown only on endoanal magnetic resonance imaging (MRI). Until now no study has compared the morphological endoanal MRI findings with histopathological aspects of the external anal sphincter. The aim of this study was to validate the MRI interpretation of the external anal sphincter using histology as a "gold standard." In this prospective study 25 consecutive unselected women (median age 48 years, range 27-72) with fecal incontinence due to obstetric trauma were assessed preoperatively with endoanal MRI. All patients underwent anterior sphincteroplasty within 6 months of the preoperative assessment. During sphincter repair, a biopsy specimen was taken both from the left and right lateral parts of the external anal sphincter. Interpretation of MRI was performed by one of the radiologists (J.S.), and biopsy specimens were evaluated by the pathologist (W.J.M.). Both were blinded to the interpretation of the other. MRI revealed external anal sphincter atrophy in 9 of the 25 patients (36%). Histopathological investigation confirmed these findings in all but one. In one additional patient atrophy was detected on histological investigation while the morphology of the external anal sphincter was classified as normal on MRI. In detecting sphincter atrophy endoanal MRI showed 89% sensitivity, 94% specificity, 89% positive predictive value, and 94% negative predictive value. MRI correctly identified sphincter morphology in 23 of 25 cases (92%). This study demonstrates that endoanal MRI accurately identifies normal and abnormal external anal sphincter morphology. Endoanal MRI is therefore a valuable preoperative diagnostic tool.

Imaging of the posterior pelvic floor

“…13). Endoanal MRI has been demonstrated to be accurate in this evaluation, which has been validated both surgically and histologically [28,30,31,32]. In a study with histological confirmation, endoanal MRI has been demonstrated to be accurate in determining the presence, as well as the absence, of external sphincter atrophy (14 of 15, 93%) [32].…”

“…Endoanal MRI has been demonstrated to be accurate in this evaluation, which has been validated both surgically and histologically [28,30,31,32]. In a study with histological confirmation, endoanal MRI has been demonstrated to be accurate in determining the presence, as well as the absence, of external sphincter atrophy (14 of 15, 93%) [32]. In a comparative study of endosonography and endoanal MRI in 20 women with faecal incontinence due to obstetric trauma, external sphincter atrophy was not identified at endosonography, when it was present at endoanal MRI in eight women [31].…”

Endoanale MR-Bildgebung

“…Zum einen hat man die Muskelmasse direkt im MR vermessen und zum anderen hat man sich bemüht, den prozentualen Anteil des Fettgewebes im Muskel zu bestimmen, da die Muskulatur und das Fettgewebe ein unterschiedlich intensives Signal im MR besitzen [18]. Zusätzlich haben die Korrelation von histopathologischen Untersuchungen und MR-Bildern bestätigt, dass die Erscheinungen tatsächlich auf einen verminderten Durchmesser der Muskelfasern und einen Fettgewebsersatz zurückzuführen sind [3]. mit dem Alter des Patienten in einen Zusammenhang zu bringen.…”

Magnetic resonance imaging and the coloproctologist

“…This type of imaging has re-established the importance of anterior sphincteroplasty in these patients [35,36]. The high-resolution imaging afforded by close field endoanal MRI has also provided quality images of these defects and the expected postoperative appearance following sphincter repair [37][38][39], giving the impression that the amount of EAS atrophy adversely correlates with functional post-surgical outcome [40]. For these views, the technique has been well described.…”