Do we need individualized interslice intervals for exoanal tomographic imaging?

Area of Science:

• Medical Imaging
• Gynecology
• Urology

Background:

• Pelvic floor dysfunction affects many women, with anal incontinence being a common symptom.
• Accurate imaging of the external anal sphincter (EAS) is crucial for diagnosing the cause of anal incontinence.
• Current imaging techniques may use individualized interslice intervals, potentially complicating analysis.

Purpose of the Study:

• To compare the diagnostic validity of a standardized 2.5 mm interslice interval versus individualized intervals for exoanal sphincter imaging.
• To assess the prediction of anal incontinence, visual analogue scale (VAS) bother score, and St Mark's incontinence score using both imaging methods.
• To evaluate the agreement between standardized and individualized interslice intervals in identifying significant residual EAS defects.

Main Methods:

• A cross-sectional study involving 1128 women with pelvic floor dysfunction symptoms.
• Tomographic exoanal sphincter imaging was performed twice: once with individualized (1.5-4.5 mm) and once with a standardized (2.5 mm) interslice interval.
• Multivariable regression and Cohen's kappa statistic were used to analyze the association between EAS defects and incontinence symptoms, and to determine method agreement.

Main Results:

• A standardized 2.5 mm interval identified significant residual EAS defects in 11.9% of women, comparable to individualized intervals (12.2%).
• Agreement between the two methods was high (Cohen's κ = 0.88), with only 2.5% of women classified differently.
• Neither interval method showed a significant difference in predicting anal incontinence or its severity scores.

Conclusions:

• A standardized 2.5 mm interslice interval is a valid and reliable method for diagnosing significant residual EAS defects.
• This standardization simplifies automated analysis of sphincter imaging, potentially improving diagnostic efficiency.
• The findings support the use of standardized intervals in routine clinical practice for exoanal sphincter imaging.