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CT Virtual CT Virtual Colonoscopy: Colonoscopy: Role in management of Role in management of colorectal polyps colorectal polyps Department of Department of Surgery Surgery Ruttonjee & TSK Ruttonjee & TSK Hospitals Hospitals Dr KY Wong Dr KY Wong

CT Virtual Colonoscopy: Role in management of colorectal polyps

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CT Virtual Colonoscopy: Role in management of colorectal polyps. Department of Surgery Ruttonjee & TSK Hospitals Dr KY Wong. Colorectal cancer. The second most common cancer in HK 2003 incidence was 2095 with 854 deaths 10% of all new cancer cases 7.8% of all cancer death - PowerPoint PPT Presentation

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Page 1: CT Virtual Colonoscopy:  Role in management of colorectal polyps

CT Virtual Colonoscopy: CT Virtual Colonoscopy: Role in management of colorectal Role in management of colorectal

polypspolyps

Department of SurgeryDepartment of SurgeryRuttonjee & TSK HospitalsRuttonjee & TSK Hospitals

Dr KY WongDr KY Wong

Page 2: CT Virtual Colonoscopy:  Role in management of colorectal polyps

Department of Surgery, Ruttonjee & TSK Hospitals 2 TSKH

Colorectal cancerColorectal cancer

The second most common cancer in HKThe second most common cancer in HK 2003 incidence was 2095 with 854 deaths2003 incidence was 2095 with 854 deaths 10% of all new cancer cases10% of all new cancer cases 7.8% of all cancer death7.8% of all cancer death Highly treatable disease if diagnosed earlyHighly treatable disease if diagnosed early

Page 3: CT Virtual Colonoscopy:  Role in management of colorectal polyps

Department of Surgery, Ruttonjee & TSK Hospitals 3 TSKH

Natural historyNatural history Precursor of 90% of colorectal cancer is the Precursor of 90% of colorectal cancer is the

adenomatous polyp, adenoma to carcinoma adenomatous polyp, adenoma to carcinoma sequencesequence

Polyp size correlates to cancer riskPolyp size correlates to cancer risk– Polyps < 1cm – 1% are cancerousPolyps < 1cm – 1% are cancerous– Polyps > 2cm – 30% are cancerousPolyps > 2cm – 30% are cancerous

T Muto et al. Evolution of CRC. Cancer 1975T Muto et al. Evolution of CRC. Cancer 1975 MJ Hill et at. Etiology of adenoma-carcinoma sequence. MJ Hill et at. Etiology of adenoma-carcinoma sequence.

Lancet 1978 Lancet 1978

Page 4: CT Virtual Colonoscopy:  Role in management of colorectal polyps

Department of Surgery, Ruttonjee & TSK Hospitals 4 TSKH

Early detection of colorectal cancerEarly detection of colorectal cancer

Detection and removal of polyps has been Detection and removal of polyps has been shown to reduce incidence of CRCshown to reduce incidence of CRC

Colonoscopy remains the gold standard in Colonoscopy remains the gold standard in management of colonic polypsmanagement of colonic polyps

F Citarda et al. Colonoscopic polypectomy in reducing F Citarda et al. Colonoscopic polypectomy in reducing CRC incidence. Gut 2001CRC incidence. Gut 2001

J Sidney et al. Prevention of CRC by colonoscopic J Sidney et al. Prevention of CRC by colonoscopic polypectomy. N Eng J Med 1993polypectomy. N Eng J Med 1993

DK Rex et al. Sensitivity of colonoscopy vs Ba enema DK Rex et al. Sensitivity of colonoscopy vs Ba enema in CRC. Gastroenterology 1997in CRC. Gastroenterology 1997

Page 5: CT Virtual Colonoscopy:  Role in management of colorectal polyps

Department of Surgery, Ruttonjee & TSK Hospitals 5 TSKH

Limitation of colonoscopyLimitation of colonoscopy Invasive procedureInvasive procedure Requires sedationRequires sedation Poor patients compliancePoor patients compliance Risk of complicationsRisk of complications Incomplete examination in 5% of casesIncomplete examination in 5% of cases Significant miss rate of adenoma up to 20%Significant miss rate of adenoma up to 20%

JB Marshall et at. Frequency of total colonoscopy. Gastrointest JB Marshall et at. Frequency of total colonoscopy. Gastrointest Endosc 1993.Endosc 1993.

DK Rex et al. Colonoscopic miss rates of adenoma. DK Rex et al. Colonoscopic miss rates of adenoma. Gastroenterology 1997.Gastroenterology 1997.

Page 6: CT Virtual Colonoscopy:  Role in management of colorectal polyps

Department of Surgery, Ruttonjee & TSK Hospitals 6 TSKH

CT Virtual ColonoscopyCT Virtual Colonoscopy

In 1994, Vining and Gelfand first described In 1994, Vining and Gelfand first described the use of helical CT volumetric data to the use of helical CT volumetric data to produce 3D images into a movie loop produce 3D images into a movie loop simulating the endoluminal view offered by simulating the endoluminal view offered by colonoscopycolonoscopy

They called this the “Virtual Colonoscopy”They called this the “Virtual Colonoscopy” DJ Vining et al. Non-invasive colonoscopy using DJ Vining et al. Non-invasive colonoscopy using

helical CT scanning and 3D reconstruction. 23helical CT scanning and 3D reconstruction. 23rdrd annual meeting, society of GI radiologists. 1994annual meeting, society of GI radiologists. 1994

Page 7: CT Virtual Colonoscopy:  Role in management of colorectal polyps

Department of Surgery, Ruttonjee & TSK Hospitals 7 TSKH

Patient preparationPatient preparation Given bowel preparation as with colonoscopyGiven bowel preparation as with colonoscopy Fecal tagging agent- decrease false +ve rate Fecal tagging agent- decrease false +ve rate Rectal tube is inserted and colon is inflated with RRectal tube is inserted and colon is inflated with R

A gently to the maximum level tolerated by patientA gently to the maximum level tolerated by patient IV antispasmodic agent ( recent study showed unnIV antispasmodic agent ( recent study showed unn

ecessary )ecessary ) A Philippe et al. Dietary fecal tagging as cleaning method. RA Philippe et al. Dietary fecal tagging as cleaning method. R

adiology 2002adiology 2002 JF Bruzzi et al. Efficacy of IV Buscopan in CT colonoscopy. JF Bruzzi et al. Efficacy of IV Buscopan in CT colonoscopy.

Eur Radiology 2003Eur Radiology 2003

Page 8: CT Virtual Colonoscopy:  Role in management of colorectal polyps

Department of Surgery, Ruttonjee & TSK Hospitals 8 TSKH

Scanning methodScanning method Helical CT scanning is performed in a single Helical CT scanning is performed in a single

breath-hold using 5mm collimation and breath-hold using 5mm collimation and reconstruction intervals of 2-3mm.reconstruction intervals of 2-3mm.

Acquisition is repeated with patient in prone and Acquisition is repeated with patient in prone and supine position supine position

Multidetector CT scanners can do it all in 20 Multidetector CT scanners can do it all in 20 seconds- improved colonic distension and reduced seconds- improved colonic distension and reduced respiratory artifactsrespiratory artifacts

AK Hara et al. CT colonoscopy: single vs multi-detector AK Hara et al. CT colonoscopy: single vs multi-detector row imaging. Radiology 2001.row imaging. Radiology 2001.

Page 9: CT Virtual Colonoscopy:  Role in management of colorectal polyps

Department of Surgery, Ruttonjee & TSK Hospitals 9 TSKH

Supination and pronationSupination and pronation

Changing position can redistribute the gas and Changing position can redistribute the gas and fluid into previous collapsed segment and increase fluid into previous collapsed segment and increase polyps detection ratepolyps detection rate

AP Royster et al. CT colonoscopy techniques. AJR 1997.AP Royster et al. CT colonoscopy techniques. AJR 1997.

Page 10: CT Virtual Colonoscopy:  Role in management of colorectal polyps

Department of Surgery, Ruttonjee & TSK Hospitals 10 TSKH

Data processingData processing

Data processing is performed with a Data processing is performed with a commercially available softwarecommercially available software

Images included 2D ( or multiplanar Images included 2D ( or multiplanar reformatted ) axial images and 3D reformatted ) axial images and 3D endoluminal fly-through view in both endoluminal fly-through view in both antegrade and retrograde directionsantegrade and retrograde directions

Page 11: CT Virtual Colonoscopy:  Role in management of colorectal polyps

Department of Surgery, Ruttonjee & TSK Hospitals 11 TSKH

2D image2D image Can be quicker to read Can be quicker to read

than a “Virtual” than a “Virtual” colonoscopycolonoscopy

Pathology is better Pathology is better delineateddelineated

lung windows useful for lung windows useful for smaller polypssmaller polyps

soft tissue windows also soft tissue windows also usefuluseful

Page 12: CT Virtual Colonoscopy:  Role in management of colorectal polyps

Department of Surgery, Ruttonjee & TSK Hospitals 12 TSKH

3D image3D image

Forward Backward

On forward view, polyp is not seen; however when a reverse colonoscopy is simulated, polyp is easily seen

Page 13: CT Virtual Colonoscopy:  Role in management of colorectal polyps

Department of Surgery, Ruttonjee & TSK Hospitals 13 TSKH

2D + 3D images2D + 3D images Most centers rely on 2D Most centers rely on 2D

image for initial interpretation image for initial interpretation and reserving 3D luminal and reserving 3D luminal view for problem solving as to view for problem solving as to decreases false positive ratedecreases false positive rate

Most centers now use Most centers now use Multiplanar Reformation Multiplanar Reformation views in which all different views in which all different 2D cuts can be seen 2D cuts can be seen juxtaposed with 3D imagesjuxtaposed with 3D images

M Macari et al. CT M Macari et al. CT colonoscopy with 2D colonoscopy with 2D and 3D correlation. and 3D correlation. AJR 2001AJR 2001

Page 14: CT Virtual Colonoscopy:  Role in management of colorectal polyps

Department of Surgery, Ruttonjee & TSK Hospitals 14 TSKH

Virtual vs. Actual ColonoscopyVirtual vs. Actual Colonoscopy

Page 15: CT Virtual Colonoscopy:  Role in management of colorectal polyps

Department of Surgery, Ruttonjee & TSK Hospitals 15 TSKH

Virtual vs. Actual ColonoscopyVirtual vs. Actual Colonoscopy

Page 16: CT Virtual Colonoscopy:  Role in management of colorectal polyps

Department of Surgery, Ruttonjee & TSK Hospitals 16 TSKH

Other potential usesOther potential uses To screen the remaining colon in incomplete To screen the remaining colon in incomplete

colonoscopy due to tortuositycolonoscopy due to tortuosity To screen the proximal colon in obstructed cancerTo screen the proximal colon in obstructed cancer Accurate location of cancer positionAccurate location of cancer position Extracolonic and incidental findings Extracolonic and incidental findings

M Helen et al. Occlusive cancer: virtual colonoscopy in M Helen et al. Occlusive cancer: virtual colonoscopy in pre-op evaluation. Radiology 1999pre-op evaluation. Radiology 1999

H Mikael et al. Extracolonic and incidental findings on CT H Mikael et al. Extracolonic and incidental findings on CT colonoscopy. AJR 2004colonoscopy. AJR 2004

Page 17: CT Virtual Colonoscopy:  Role in management of colorectal polyps

Department of Surgery, Ruttonjee & TSK Hospitals 17 TSKH

Other potential usesOther potential uses Preoperative T and N staging of CRC with IV Preoperative T and N staging of CRC with IV

contrast CT colonoscopycontrast CT colonoscopy Detection of colonic stenosis in Crohn’s colitisDetection of colonic stenosis in Crohn’s colitis

A Filippone et al. Pre-op T & N staging in CRC: contrast A Filippone et al. Pre-op T & N staging in CRC: contrast enhanced CT colonoscopy. Radiology 2004enhanced CT colonoscopy. Radiology 2004

Y Ota et al. Value of CT colonoscopy in Crohn’s colitis. Y Ota et al. Value of CT colonoscopy in Crohn’s colitis. Abdominal imaging 2003Abdominal imaging 2003

Page 18: CT Virtual Colonoscopy:  Role in management of colorectal polyps

Department of Surgery, Ruttonjee & TSK Hospitals 18 TSKH

Results of polyps detectionResults of polyps detection(Vs colonoscopy )(Vs colonoscopy )

StudyStudy PatientPatient Sensitivity ( % )Sensitivity ( % ) Specificity ( % )Specificity ( % ) Patient characteristicPatient characteristic

>10mm>10mm 6-9mm6-9mm <5mm<5mm >10mm>10mm 6-9mm6-9mm <5mm<5mm

AK AK Hara Hara 19961996

1010 100100 7171 4545 __ __ __ Symptomatic patientSymptomatic patient

AK AK Hara Hara 19971997

7070 7575 6666 4545 9090 6363 8080 Symptomatic patientSymptomatic patient

HM HM Fenlon Fenlon 19981998

3838 100100 100100 __ __ __ __ Patients with recent Dx Patients with recent Dx CRC,CRC,100% cancer detection 100% cancer detection raterate

HM HM Helen Helen 19991999

100100 9191 8282 5555 __ __ __ High risk patientHigh risk patient

Page 19: CT Virtual Colonoscopy:  Role in management of colorectal polyps

Department of Surgery, Ruttonjee & TSK Hospitals 19 TSKH

Results of polyps detectionResults of polyps detection(Vs colonoscopy )(Vs colonoscopy )

StudyStudy PatientPatient Sensitivity ( % )Sensitivity ( % ) Specificity ( % )Specificity ( % ) Patient Patient characteristiccharacteristic>10mm>10mm 6-9mm6-9mm <5mm<5mm >10mm>10mm 6-9mm6-9mm <5mm<5mm

Yee 2001Yee 2001 300300 9090 80.180.1 59.159.1 72 ( overall )72 ( overall ) Asymptomatic Asymptomatic + symptomatic + symptomatic patientspatients100% cancer 100% cancer detection ratedetection rate

Carrascosa Carrascosa 20032003

500500 100100 95.695.6 87.887.8 100100 91.491.4 86.986.9 Symptomatic Symptomatic and high risk and high risk patientspatients

J Perry J Perry 20032003

12331233 93.893.8 93.993.9 88.788.7 9696 92.292.2 79.679.6 Asymptomatic Asymptomatic adultsadults

S Jacob S Jacob 2003 2003

13241324 8181 6262 4343 9595 __ __ Meta-analysisMeta-analysis

Page 20: CT Virtual Colonoscopy:  Role in management of colorectal polyps

Department of Surgery, Ruttonjee & TSK Hospitals 20 TSKH

RHTSK- backgroundRHTSK- background >500 colonoscopies performed per year>500 colonoscopies performed per year Common indication: surveillance for coloreCommon indication: surveillance for colore

ctal polypsctal polyps Long waiting list for colonoscopyLong waiting list for colonoscopy New multidetector CT scanner is available rNew multidetector CT scanner is available r

ecentlyecently ? Can CT virtual colonoscopy share the wor? Can CT virtual colonoscopy share the wor

kload of colonoscopykload of colonoscopy

Page 21: CT Virtual Colonoscopy:  Role in management of colorectal polyps

Department of Surgery, Ruttonjee & TSK Hospitals 21 TSKH

RHTSK- patient and methodRHTSK- patient and method Patients with bowel symptoms and require colonoscopy foPatients with bowel symptoms and require colonoscopy fo

r investigation between June to Sept 2004r investigation between June to Sept 2004 Bowel preparation with 2L Klean prepBowel preparation with 2L Klean prep Fecal tagging agent is givenFecal tagging agent is given CT colonoscopy followed by conventional colonoscopyCT colonoscopy followed by conventional colonoscopy Both 2D and 3D images are created and reviewed by radiolBoth 2D and 3D images are created and reviewed by radiol

ogistsogists CT colonoscopic findings are correlated with standard coloCT colonoscopic findings are correlated with standard colo

noscopic findingsnoscopic findings Both investigators are blinded from the resultsBoth investigators are blinded from the results

Page 22: CT Virtual Colonoscopy:  Role in management of colorectal polyps

Department of Surgery, Ruttonjee & TSK Hospitals 22 TSKH

RHTSK- resultsRHTSK- results N: 51 ( M:F = 24:17 ); ( mean age: 61.9 years )N: 51 ( M:F = 24:17 ); ( mean age: 61.9 years ) Results:Results:

– Normal study in 27 patientsNormal study in 27 patients– 19 adenomas and 6 cancer were detected19 adenomas and 6 cancer were detected– Overall sensitivity for adenomatous polyp detection rate is 83.3%Overall sensitivity for adenomatous polyp detection rate is 83.3%– Sensitivity for polyp> 5mm- 9mm: 85.3% Sensitivity for polyp> 5mm- 9mm: 85.3% – Sensitivity for polyp< 5mm: 40% Sensitivity for polyp< 5mm: 40% – 100% cancer detection 100% cancer detection – Two false +ve polyps detected: poor bowel preparationTwo false +ve polyps detected: poor bowel preparation– 15 patients had 20 extracolonic findings of moderate to high 15 patients had 20 extracolonic findings of moderate to high

importanceimportance Renal stones, bladder stone, hydronephrosis, AAA, GS, ductal Renal stones, bladder stone, hydronephrosis, AAA, GS, ductal

stone, cirrhosis, liver abscess, liver and lung secondarystone, cirrhosis, liver abscess, liver and lung secondary

Page 23: CT Virtual Colonoscopy:  Role in management of colorectal polyps

Department of Surgery, Ruttonjee & TSK Hospitals 23 TSKH

Limitation of CT colonoscopyLimitation of CT colonoscopy Relatively low sensitivity and specificity for Relatively low sensitivity and specificity for

polyps < 5mmpolyps < 5mm Significant false positive polyps detection rateSignificant false positive polyps detection rate Problem in detection of flat adenomaProblem in detection of flat adenoma Relatively lengthy data interpretation time- 20minRelatively lengthy data interpretation time- 20min Radiation exposureRadiation exposure CostCost

Page 24: CT Virtual Colonoscopy:  Role in management of colorectal polyps

Department of Surgery, Ruttonjee & TSK Hospitals 24 TSKH

ConclusionConclusion Surveillance of colonic polyps can reduce CRC Surveillance of colonic polyps can reduce CRC

incidenceincidence Colonoscopy remains the gold standard for Colonoscopy remains the gold standard for

management of colonic polyps but has limitationmanagement of colonic polyps but has limitation CT Virtual Colonoscopy is a non-invasive CT Virtual Colonoscopy is a non-invasive

procedure and is comparable with standard procedure and is comparable with standard colonoscopy for detection of clinically important colonoscopy for detection of clinically important polypspolyps

Page 25: CT Virtual Colonoscopy:  Role in management of colorectal polyps

Department of Surgery, Ruttonjee & TSK Hospitals 25 TSKH

ConclusionConclusion

It can share the workload of colonoscopy in It can share the workload of colonoscopy in surveillance of colonic polyps especially for surveillance of colonic polyps especially for those patient reluctant for colonoscopy and those patient reluctant for colonoscopy and had incomplete colonoscopy beforehad incomplete colonoscopy before

Further development and studies require to Further development and studies require to solve the problems of false +ve rate and flat solve the problems of false +ve rate and flat adenomaadenoma