Endoluminal Ultrasound

1. Endoluminal Ultrasound Dr. Omar Felix 10/5/2011

2. Endorectal Ultrasound • Diagnostic procedure of choice in evaluation of anorectal disorders. • Best imaging modality for staging of rectal cancer • Invaluable in workup for fecal incontinence and suppurative anorectal conditions.

3. History • Introduced in 1952 • Wild and Reid • Never used in clinical practice • Clinical Practice in 1983 • Dragsted and Gammelgaard • Used 4.5 Mhzprostate ulstrasound probe • 1985: Modification of TNM staging • Hildebrandt and Feifel • 3D ultrasound recently developed. Currently being evaluated in efficacy compared to 2D ultrasound and MRI.

4. Equipment and Technique • Endocavitary probe with rotating transducer • 7 or 10 MHz Transducer • Latex Balloon covering the probe which is filled with water to distend the rectum. • Phosphossoda enema for bowel prep

5. Equipment and Technique • Left lateral decubitus position • DRE and proctoscopy • Wide bore proctoscope to facilitate positioning of probe above lesion. • Balloon is filled with 30-60 cc of water and real time image obtained.

6. Image Interpretation • 5 Layer Model • Beynon and Colleagues • Three hyperechoic (white) layers separated by two hypoechoic (black) layers. • 1st White layer: Interface between balloon and mucosa • 2nd black layer: mucosa and muscularis • 3rd white layer: submucosa • 4th black layer: Muscularis propria • 5th white layer: interface between muscularis propria & fat

7. 5 Layer Model

9. Assessment of Rectal Neoplasms • Depth of Invasion • Ultrasound Staging Classification (uTNM) • 87%-96% Accuracy rate

10. uTNM Staging Classification

12. ERUS

13. T1

14. T2

15. T3

16. Assessment of Rectal Neoplasms • Nodal Involvement • Associated with higher rates of local recurrence and lower survival rates • Accuracy of ERUS is 50-88% • False positives with inflammatory nodes or blood vessels • Nodes >5mm are highly suspicious • Hypoechoic with irregular borders

17. Nodal involvement

18. Accuracy of ERUS • Accurate in determining depth of invasion • Moderately accurate in assessment of Lymph Node involvement. • Significant learning curve • Highly operator dependent

20. Factors for Misinterpretation • Close proximity to anal verge • Inproper balloon inflation • Artifact from air or stool • Refraction artifacts • Post-biopsy or surgical changes • Hemorrhage • Pedunculated tumors

21. Post-op Follow up • ERUS may improve ability to diagnose recurrence in 30% • Baseline Ultrasound at 3mths • Optimal interval and length of time for serial follow up has not been determined. • Suggested every 3-4 mths for 1st 2 years then every 6 months for 5 years

22. Endoanal Ultrasound • Useful for evaluation of anal canal in both benign and malignant disease • fecal incontinence • perianal abscesses • anal canal neoplasms • Clearly defines sphincter anatomy

23. Endoanal Ultrasound • Similar equipment and technique • Image Interpretation • Three levels • Upper Anal canal: delineated by puborectalis muscle • Mid Anal Canal: can make perineal body measurements and visualize both anal sphincters • Low Anal Canal: internal anal sphincter is no longer seen.

24. EAUS- Sphincter Defect

25. EAUS- Fistula-in-Ano

26. uTMN for Anal Cancer

27. Summary • Endoluminal Ultrasound is useful for benign and malignant anorectal conditions. • Best Imaging technique to stage anorectal cancers • Have an important role for followup • 3D ERUS will prove to be advantageous but will need further study.