Diagnostic performance of dynamic MR defecography in assessment of dyssynergic defecation

Pimpapon Thanaracthanon; Kewalee Sasiwimonphan; Angkana Sunthornram; Mukesh G Harisinghani; Thitinan Chulroek

doi:10.1007/s00261-023-04010-z

Diagnostic performance of dynamic MR defecography in assessment of dyssynergic defecation

Abdom Radiol (NY). 2023 Nov;48(11):3458-3468. doi: 10.1007/s00261-023-04010-z. Epub 2023 Aug 4.

Authors

Pimpapon Thanaracthanon^{1

2}, Kewalee Sasiwimonphan², Angkana Sunthornram², Mukesh G Harisinghani³, Thitinan Chulroek^{4

5}

Affiliations

¹ Department of Radiology, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand.
² Department of Radiology, King Chulalongkorn Memorial Hospital, 1873 Rama 4 Road, Pathumwan, Bangkok, 10330, Thailand.
³ Department of Radiology, Massachusetts General Hospital, 55 Fruit Street, White 270, Boston, MA, 02114, USA.
⁴ Department of Radiology, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand. thitinan.c@chula.ac.th.
⁵ Department of Radiology, King Chulalongkorn Memorial Hospital, 1873 Rama 4 Road, Pathumwan, Bangkok, 10330, Thailand. thitinan.c@chula.ac.th.

PMID: 37542178
DOI: 10.1007/s00261-023-04010-z

Abstract

Purpose: To assess diagnostic performance of MR defecographic findings in diagnosis of dyssynergic defecation (DD).

Methods: This retrospective study included 46 patients with chronic constipation who met the Rome IV criteria for diagnosis of present or absent DD and underwent MRI between Jan 2015 and June 2020. Patients were divided into DD group (n = 24) and non-DD group (n = 22). Nine parameters were analyzed by two radiologists: anorectal angle (ARA) and M line at rest, defecation, and change between 2 phases; anal canal width; prominent puborectalis muscle; abnormal evacuation. Receiver operating characteristic (ROC) curves were plotted to extract the optimal cut-offs and area under the curve (AUC). Multivariate analysis was performed.

Results: Seven findings showed statistically significant difference between DD and non-DD groups. M line at defecation had highest odds ratio, followed by ARA change, ARA at defecation, M line change, prominent puborectalis muscle, abnormal evacuation and anal canal width, respectively. ARA change and prominent puborectalis muscle had highest specificity (95.5% and 100%, respectively). The optimal cut-offs of ARA at defecation, ARA change, M line at defecation, M line change and anal canal width were 122°, 1.5°, 3.25 cm, 1.9 cm and 8.5 mm, respectively. Multivariate logistic regression revealed two significant findings in differentiating between DD and non-DD, including M line at defecation (OR 23.31, 95% CI 3.10-175.32) and ARA at defecation (OR 13.63, 95% CI 1.94-95.53) with sensitivity, specificity, PPV, NPV and AUC of 79.2%, 95.5%, 95%, 80.8% and 0.87(95% CI 0.78-0.97), respectively.

Conclusion: MR defecography has high diagnostic performance in diagnosis of DD. Although M line and ARA at defecation are two significant findings on multivariate analysis, ARA change less than 1.5 degrees and prominent puborectalis muscle have good specificity in DD diagnosis.

Keywords: Anismus; Constipation; Dyssynergic defecation; MR defecography.