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Rectal Ultrasound

Jay Patti

Jay PattiGillian Lieberman, MD

Gillian Lieberman, MD

September 2001

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• CW is a 66 year old Caucasian female who presented with a four month history of painless rectal bleeding.

Patient’s History

Jay PattiGillian Lieberman, MD

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Multiple axial images of the pelvis with contrast

Multiple axial images of the pelvis with contrast

Rectal Mass

All images are from BIDMC PACS

Jay PattiGillian Lieberman, MD

Oral and IV contrast

Our Patient: Pelvic CT

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Multiple axial images of the pelvis with contrast

CT does not yield information about tissue type,depth of invasion, or cell cytology

Jay PattiGillian Lieberman, MD

Oral and IV contrast

Our Patient: Rectal Cancer

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Multiple axial images of the pelvis with contrast

Jay PattiGillian Lieberman, MD

Our Patient: Rectal Cancer on Pelvic CT

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CT

• While CT is a good means of identifying masses in the pelvis its greater utility is in identifying distant organ involvement. CT yields little information on the depth of invasion locally of rectal cancer unless metastases are seen. (Stage IV)1,7

Jay PattiGillian Lieberman, MD

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Colonoscopy• Her colonoscopy showed a pale nodular non-bleeding mass

protruding into the lumen of her upper rectum. • Colonoscopy offers the ability to directly visualize the

tumor but lacks the ability to define depth of invasion. Colonoscopy is also used to evaluate the rest of the colon for other possible lesions. Under direct visualization with colonoscopy one can biopsy lesions and send tissue samples for cytology.

Jay PattiGillian Lieberman, MD

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Jay PattiGillian Lieberman, MD

Our patient was diagnosed with rectal cancer by CT and colonoscopic biopsy. She was referred for endorectal ultrasound for further staging

Our Patient

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Endorectal Ultrasound

• Reported to be 72%-97% accurate in determining depth of tumor invasion with 12% overstaged and 9% understaged. Sensitivity is 86% and specificity is 33%.2

• Sensitivity and specificity of determining perirectal lymph node involvement is between 60-90% for both.

• 6-8 weeks after radiation therapy endorectal US measures resulting fibrosis and is hence less useful although many have reported that if residual tumor remains it will be confined to the area of fibrosis.6

Jay PattiGillian Lieberman, MD

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• Patients need only a phosphate enema prior to examination.• No sedation, bowel preparation, or patient monitoring is

necessary. • Patient placed in the left lateral decubitus position with

knees and hips flexed. • Ultrasound transducer is surrounded by an expandable

balloon that must be filled with water after it is placed in the rectum.

• Special care must be take to assure that there is no air in the balloon (shadowing artifact).

• A condom containing transducer jelly is placed over the transducer before insertion in the rectum.

Preparation

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• Most clinicians subscribe to a 5 layer model when analyzing the appearance of the rectal wall. The normal rectum appears as hyper- and hypo-echoic bands around a hypoechoic lumen. There is some controversy as to the anatomic correlation of the bands (anatomic layers vs. anatomic interfaces). There is agreement that the outer hypoechoic band represents the muscularis propria. (The muscularis propria is important for staging)

Normal Rectum

Jay PattiGillian Lieberman, MD

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Normal Rectum

Perirectal Fat

Muscularis propria

Submucosa

Muscularis Mucosa

Balloon/Mucosa Interface

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• Anal Verge - If the tumor is at the anal verge it may be hard to pass the transducer

• Transducer angle - Oblique angle of the wall may cause blurring and overestimation

• Balloon Inflation - Over inflation causes stacking of layers and hence overestimation

• Air - In the balloon, ulcer or necrotic tumor will cause distant shadowing.

• Stool - Artifact of mixed echotexture can appear similar to villous tumors.

• Surface Contact - Villous adenomas have air in the villi

Pitfalls

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• 15% of all cancers in men and women occur in the lower GI tract; 33% of which occur in the rectum1

• Survival is inversely proportional to stage• Transrectal US is most influential in the treatment

of lower stage tumors.

Rectal Cancer

Jay PattiGillian Lieberman, MD

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• T1 – Submucosal involvement only; Treatment: Full thickness local excision. Low likelyhood of lymphatic spread (6-11%).

• T2 – Into but not beyond the muscularis propria. There may be thickening of the muscularis propria with preservation of the hyperechoic perirectal fat layer; Treatment: Local excision (higher rate of recurrence) Lymph node involvement in 10-35%.

• T3 – Tumor extends beyond the muscularis propria into the perirectal fat area; Treatment: Low anterior or abdominoperineal resection with adjuvant preoperative chemotherapy and/or radiation.

• T4 – Invasion of adjacent organs or the pelvic wall; Treatment: depends on the extent of and organs involved.

Staging

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Perirectal FatMuscularis propriaSubmucosaMuscularis MucosaBalloon/Mucosa Interface

Loss of clear perirectal fat layer could be artifactual

Jay PattiGillian Lieberman, MD

Our Patient

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Submucosa layer appears intact

Jay PattiGillian Lieberman, MD

Our Patient

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Perirectal fat layer appears disrupted

Jay PattiGillian Lieberman, MD

Our Patient

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Perirectal fat layer appears disrupted

Patient was staged as T2, but T3 disease could not be ruled out

Jay PattiGillian Lieberman, MD

Our Patient

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Jay PattiGillian Lieberman, MD

Our Patient

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Jay PattiGillian Lieberman, MD

Our Patient

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MR

• Sensitivity is 89% and specificity is 68%. US:Sensitivity is 86% and specificity is 33%.4

• Although MR is slightly better at staging rectal cancer, it is much more expensive.3,4,5

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Summary

• Normal Rectum & Rectal CancerFive Layers: Perirectal Fat, Muscularis propria, Submucosa, Muscularis Mucosa,

Balloon/Mucosa Interface

Four Stages: I, II, III, IV• CT• Colonoscopy• Rectal US

Preparation TechniqueFindings

• MR

Jay PattiGillian Lieberman, MD

We discussed:

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References1. Kruskal JB, Kane RA, Sentovich SM, Longmaid HE. Pitfalls and Sources of Error in Staging Rectal Cancer with

Endorectal US. 1997 Radiographics 17(3)609-6262. Gavioli M, Bagni A, Piccagli I, Fundaro S, Natalini G. Usefulness of endorectal ultrasound after preoperative

radiotherapy in rectal cancer: comparison between sonographic and histopathologic changes.Dis Colon Rectum. 2000 Aug;43(8):1075-83.

3. Blomqvist L, Machado M, Rubio C, Gabrielsson N, Granqvist S, Goldman S, Holm T. Rectal tumour staging: MR imaging using pelvic phased-array and endorectal coils vs endoscopic ultrasonography.Eur Radiol. 2000;10(4):653-60.

4. Gualdi GF, Casciani E, Guadalaxara A, d'Orta C, Polettini E, Pappalardo G. Local staging of rectal cancer with transrectal ultrasound and endorectal magnetic resonance imaging: comparison with histologic findings.Dis Colon Rectum. 2000 Mar;43(3):338-45.

5. Hunerbein M, Pegios W, Rau B, Vogl TJ, Felix R, Schlag PM. Prospective comparison of endorectal ultrasound, three- dimensional endorectal ultrasound, and endorectal MRI in the preoperative evaluation of rectal tumors. Preliminary results. Surg Endosc. 2000 Nov;14(11):1005-9.

6. Rau B, Hunerbein M, Barth C, Wust P, Haensch W, Riess H, Felix R, Schlag PM. Accuracy of endorectal ultrasound after preoperative radiochemotherapy in locally advanced rectal cancer.Surg Endosc. 1999 Oct;13(10):980-4.

7. Kim NK, Kim MJ, Yun SH, Sohn SK, Min JS. Comparative study of transrectal ultrasonography, pelvic computerized tomography, and magnetic resonance imaging in preoperative staging of rectal cancer.Dis Colon Rectum. 1999 Jun;42(6):770-5.

8. Saclarides TJ. Endorectal ultrasound. Surg Clin North Am. 1998 Apr;78(2):237-49.

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Acknowledgments

• Larry Barbaras and Cara Lyn D’amour, our web masters

• Gillian Lieberman, MD• Pamela Lepkowski

Jay PattiGillian Lieberman, MD