Mark Wax MD, Arie Kaufman PhD,Mark Wax MD, Arie Kaufman PhD,

Jerome Liang PhD, and Kevin Kreeger MSJerome Liang PhD, and Kevin Kreeger MS

Advancing Virtual Colonoscopy to Practice

• Introduction

• Cited Limitations

• Approach to Overcoming Obstacles

• Conclusions

Advancing Virtual Colonoscopy to Practice

Colorectal Cancer Screening Guidelines(Gastroenterology, 1997)

• Screening Modality–Safe

–Acceptable

–Available

–Cost Effective

• An alternative endoscopic procedure for An alternative endoscopic procedure for

examining the inner surface of the human colonexamining the inner surface of the human colon

• Overcoming disadvantages of existing proceduresOvercoming disadvantages of existing procedures

3D Virtual Colonoscopy3D Virtual Colonoscopy

40 sec CT scan of patient’s abdomen40 sec CT scan of patient’s abdomen

Reconstruction of 3D colon modelReconstruction of 3D colon model

Pre-processing of colon modelPre-processing of colon model

Interactive navigation inside colonInteractive navigation inside colon

Virtual Colonoscopy ProcedureVirtual Colonoscopy Procedure

• Introduction

• Cited Limitations

• Approach to Overcoming Obstacles

• Conclusions

Advancing Virtual Colonoscopy to Practice

New England Journal of Medicine(Nov 11, 1999)

• “A Comparison of Virtual and Conventional Colonoscopy for the Detection of Colorectal Polyps”

H. Fenlon et. al, Boston University

• “Virtual Colonoscopy - Promising but Not Ready for Widespread Use”

J. Bond, Minneapolis VA

Cited Limitations

• Patient Preparation–Bowel Cleansing

• Technique–Gas distention of colon

–Time to process data/images to determine whether optical colonoscopy is required

Cited Limitations

• Image Interpretation–Time consuming

–Steep learning curve

–Technically inadequate studies

• Retained stool/fluid• Contracted segments

–Sensitivity/specificity

Cited Limitations

• Cost–Expensive scanning hardware

–Needs to be less than optical colonoscopy

• Introduction

• Cited Limitations

• Approach to Overcoming Obstacles

• Conclusions

Advancing Virtual Colonoscopy to Practice

Bowel Cleansing

• Contrast Agents - Barium Sulfate, Gastrograffin

• Low residue diet

• Electronic Cleansing

Inner View of the ColonInner View of the Colon

Technique

• Colon Distention –CO2 instead of room air

Fast reabsorbtion Increased patient comfort

• Collapsed colon segments–Glucagon

–Supine and Prone Views

Image Interpretation

• Steep Learning Curve –Similar to any new technology or

procedure

• Virtual fly-through interface mimics optical colonoscopy

User InterfaceUser Interface

Time to Process Data and Interpret Images

• Volume rendering with SGI and PC platforms

• Navigation–Guided using colon centerline

– Interactive with the click of a mouse

1 2

3 4

Sensitivity/Specificity

• Stool/Fluid tagging

• Electronic Cleansing

• Electronic Biopsy

Costs

• Estimated cost - $200-$300–Less than Medicare reimbursement for

Abdominal and Pelvic CT ($410)

–Less than Physician charges for optical colonoscopy ($700)

• Only requires 10 minutes of CT scanning time

• Increased utilization of CT scanners

• Introduction

• Cited Limitations

• Approach to Overcoming Obstacles

• Conclusions

Advancing Virtual Colonoscopy to Practice

Virtual Colonoscopy System

• Technical Advances–Speed–Automation–Comfort–Cost effective

• Future–System still evolving, not yet frozen–Large scale clinical trial