Presentation - OMED: World Organization for Digestive Endoscopy

CT Colonography:OMED 2005Beth G. McFarland, MDSt. Luke’s Hospital / CDIAdjunct Professor, Wash U

Achievements and challenges3D PVR (perspective VR)3D transparency/ edge-enhanced

ObjectivesI. Technique advances» CT protocol (1DCT - 64DCT)» 2D MPR – 3D image displays» Patient factors- bowel prep / insufflationII.Standardization of reporting: C-RADSIII. ACR status: local coverage decisions

Evolution of 3D advancements** Acquisition AND Image display1998, 1DCT5 x 8 x 2 mm400images2003, 16DCT0.75 (1.0 EST) x15 mm x 1 mm800 +images

CTC Protocol• Two types of protocols evolving:1. CTC for patients at high risk for colon ca-- evaluate colon + staging (IV contrast)2. CTC for patients at low risk-- evaluate colon + extra-colonic (no IVcontrast, low dose)

CT Dose issues• High contrast interface of COLONIC polypand air permits a decrease of mAs» Macari, et al, RAD 2001: 4DCT- 1 mm EST, 50 eff mAS = 5-7 mSV (similar to BE)» Iannaconne, et al, RAD 2003: 4DCT- 2.5 mm EST, 10 eff mAS = 1.8-2.4 mSV• Low contrast interface of EXTRACOLONICorgans (w/o IV contrast) can becompromised by a decrease of mAs

Colon phantom- 16DCT11 x 1 mm6mm11 x 3 mm0.75 mm detector, 1.0 EST, beam pitch 1.550 eff mAs

16D CT25 eff mAs100 eff mAs50 eff mAs160 eff mAs

Key patient factors(input)Bowel prep +Before CTAt CT

Dry Tagging - Barium• 50 patients - FT (mag citrate,barium, diet)•50 patients: non-FT (pol gylcol)•FT increased specificity (88%,14/16), compared to non-FT (77%,17/20)•FT had decreased discomfort andside effects/ better willingnesswith catharsisLefere P, Radiology 2002;224:393-403

Wet tagging - iodineBefore subtractionAfter subtractionZalis M. et al, AJR 2001;176:646-648

Overview of large trials• Johnson et al, Gastro 03• Pickhardt et al, NEJM 03• Cotton et al, JAMA 04• Iannaconne et al, Gastro 04• Rockey et al, Lancet 05Stool TaggingNoYesNoYesNo

Recent tagging protocolsPickhardt et alIannaccone et al(NEJM 2003) (Gastro 2004)Diet Clear liquid Low fiberCatharsis Phospha soda 90 cc NONETagging Gastro 120 cc Gastro 200 ccBarium 2% 500 ccSubtraction YES NO2D – 3D 3D primary review 2D primary review

Bowel preparation• Diet» Clear liquids or low fiber (Nutra-prep, EZEM)• Catharsis» Phospha-soda (45 cc), or Mg citrate• Tagging (w/o subtraction)» Gastrograffin 60 cc + Barium 2% 250 cc» Barium 40% (Tagitol V)- 20 cc x 3» (Barium 2% 500 cc)Futurechanges**

Insufflation per rectum

CT Colonography(failed endo, BE)APRPO

SupineLeft lateraldecubitis40 yr. old male,incompletecolonoscopy

3D CT endoscopic display1DCT5 x 8 mm2 mm RI0.65mm 3Vitrea TM

Interactivity of 2D MPR and 3D CT2D Axial MPR2D Coronal MPR3D CT endoscopic

2D- 3D interactivity• 2D multiplanar reformation» time-efficient evaluation of polyp detection /characterization» provides extra-luminal orientation» maintains source density data (HU)• 3D endoscopic PVR» can be used as primary review to detect- mayimprove surface area visualization» demonstrates overall morphology of lesion

Edge- enhanced (BE) roadmap

C-RADS:Structured reporting- images/textVirtual colonoscopy workinggroupconsensus statement(Radiology 2005, in press)

C-RADS:Structured reporting• Image quality per segment:- distention, fluid- stool, tortuosity• Colorectal findings- size/location of lesions- 2D and 3D images of each

C-RADS:Structured reporting• Possible surveillance intervals- > 1 cm : colonoscopy- 6-9 mm: colonoscopy vs. follow• Extra-colonic findings:- to discern significant lesions(eg, AAA, adenopathy)

AxialReporting of findingsPol 1= HF polypSagProneAxial1 cm HF polyp(P=265, 634, -279)Supine

CoronalPol 2= sigmoid polypAxial5 mm sigmoid polyp(P= 371,561,-421)

Edge-enhanced CT overviewLPOPol 1Pol 2RPOAP view

Polyp size measurement• Polyp size is significant for clinicalmanagement and stratification of resultsduring validation» < 5 mm, 5-9 mm, > 10mm• CLINICAL VARIABILITY exists• CTC can provide both 2D and 3D tools forlinear and volumetric (in development)measurements

Change of morphologyof pedunculated 12 mm polypSupineProne

Case 913.4Sigmoid polypPolyp size measurement:**** measure long axis of polyphead w/o stalkstalk14 mm CT= 9, 11, 11, 11 mm

CPT codingReimbursement

ACR report of CPT codesEffective as of July 2004:• Two category III codes created for CTC» 0066T asymptomatic (screening)» 0067T symptomatic (diagnostic)

ACR report of CPT codesAs of July 2004:• Category III codes are for trackingpurposes (not FDA approved, no RVU’s)» potentially can be reimbursed at individuallevel based on local payor policies» local coverage decisions (LCD’s) can be madefor extended prospective reimbursementBarish M. Billing and reimbursement of VC, Intl Sym of VC 04

Local coverage decisions (LCD’s)• Can help promote localreimbursements for specific patientcohorts• ACR offers central networking andcoordination for physicians and thirdparty payers» CAC (Carrier Advisory Committee)» MCN (Managed Care Network)

Clinical vignettes for CTCreimbursement• Patients who have had incomplete colonoscopy» CAC approved in 9 states• Patients at risk for colonoscopy» pending• Frail / debilitated / elderly» pending• Screening in underserved areas» Madison, WI (Pickhardt)

Flat T3 lesion at colonoscopymissedat CTCColonoscopyCTCin retrospect

Missed flat T3 lesionat CTCpronesupine3D fly-through

Advanced rectal lesionmissedat prior colonoscopy

Missedrectal calocal stagingdistant staging

Performance• Effective multi-disciplinarycollaborations• Proper selection of patientcohortsPractice• Shared medical decisionmaking with patients• Ongoing Q/A

The 6 th International Symposium onVirtual ColonoscopyOctober 17-18, 2005Boston, MAw w w . v i r t u a l c o l o n o s c o p y . n e tw w w . b u . e d u / c m e