Handout rc612 b_hallett_le cta_sm

PERIPHERALCTA

RichardL.Hallett,MDChief,CardiovascularImagingNorthwestRadiologyNetworkIndianapolis,INAdjunctAssistantProfessor–RadiologyStanfordUniversityStanford,CA

RC612B 3December2015 0830–1000

Outline

§  CTAAcquisitionTechniquesú  ScanAcquisitionú  ContrastMediuminjectionú  Reconstruction

§  ClinicalEfficacyinPAD§  CostEffectiveness

Handout:stanford.edu/~hallettchoosefolder“RSNA2015”

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CTAIndicationsinPAD

" IntermittentClaudication" CriticalLimbIschemia" AcuteIschemia(urgent)" MonitoringofTherapy(complications)

CTABenefits/Limitations

§  Non-invasive(DSA)§  SpatialResolution

(MRA)§  QuickAcquisition§  (mostly)Operator

Independent

§  IonizingRadiation§  NephrotoxicContrast§  SpatialResolution(DSA)§  NosamesessionTx§  Nofloworpressure

measurements

CTAAcquisition" ScanAcquisition" ContrastMediumInjection

CTAScanAcquisition


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Optional Scanning Range 2 above the knees à toes Always pre-programmed, but only initiated by RT if no contrast in pedal vessels

Scanning Range 1 celiac artery (~T12) à toes (105 – 130 cm)

Recons: Thin, overlapped FOV = greater trochanters

PeripheralCTAScanAcquisition/Recon

DetectorConfiguration

(mm)TI/360°(mm)

TableSpeed(mm/s)

ScanningTime(s)

16-ChannelMDCT

16×.75 18 36 30-4016×.63 18 35 30-40

16×1.5 33 66 15-2016×1.25 35 70 15-20

~35 mm/s slow slow

fast fast

Anatomic coverage: 105 – 130cm

64-ChannelMDCT

64×.63 55 92 11-14

64×.60 29 78 13-17 fast very

~85 mm/s

~65 mm/s

Speedconsiderationsfor>64sliceCTA

§  OutrunningBolus§  Delayedfillingofdistalarteries

Free-FlapPlanningCTA

preprogrammed, optional 2nd acquisition

Arteriomegaly

1st acquisition

Table speed (mm/s)

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vAO->POP (mm/s)

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Aorto-popliteal transit speed (mm/s)

Table speed (mm/s)

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vAO->POP (mm/s)Cu

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Peripheralarterialboluspropagation

< .01

~.33

> .50

Fleischmann D and Rubin GD. Radiology 2005, 1076-1082

ContrastAdministrationforperipheralCTA

Fleischmann D. How to design injection protocols for multiple detector-row CT angiography (MDCTA). Eur Radiol. 2005 Dec 1;15 Suppl 5:E60–5.

ContrastconsiderationsforperipheralCTA

§  Aorto-poplitealtransittime:4-24sec(10sec)ú  Contrastspeed:29-177mm/s

§  Biphasicinjectionsyieldmoreconsistentenhancementprofile

Fleischmann et al. JVIR 2006, 17(1) 3-26.

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INPUT intravenous injection rate (mL/s)

OUTPUT arterial enhancement (ΔHU)

Phase I (surge phase)

Phase II (continuing phase)

Biphasic Injection for Peripheral CTA

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Biphasic Injection

Fleischmann D. Eur. J. Radiol. 2003 Mar 1;45 Suppl 1:S88–93.

PatientFactors

§ Arterialenhancementisinverselyrelatedto:§ Cardiacoutput(CO)

§ Centralbloodvolume(CBV)§ CO(andCBV)correlatewithbodyweight

§  atleastinpts.with~normalcardiacfunction

§ Weight-baseddosinghelpsconsistency

1) Hittmair & Fleischmann, JCAT 2001

usually unknown

IntegratedContrast/ScanProtocol

" Simple,weightbasedinjectionvolumesandflowrates,combinedwithafixedscantimeorscantime/diagnosticdelaysum.

" automatedbolustriggering" Usephysiologynotscannerspeed" BENEFITS:

" Decreasepatienttopatientvariabilityinscanquality" Optimizeimagingtiming" Imageallofthecontrastgiven!

" (Potentially)savecontrast

STANFORDIntegratedScanning-InjectionProtocol:(Siemens)

§ Scantime: 40sforALLpatients(pitchvariable)§  Inj.duration:35sforALLpatients§ Delay: bolustriggering

weight Biphasic Injection <55kg 20 mL (4.0mL/s) + 96 mL (3.2mL/s) <65kg 23 mL (4.5mL/s) + 108 mL (3.6mL/s)

75kg 25 mL (5.0mL/s) + 120 mL (4.0mL/s) >85kg 28 mL (5.5mL/s) + 132 mL (4.4mL/s) >95kg 30 mL (6.0mL/s) + 144 mL (4.8mL/s)

ST.VINCENTIntegratedScanning-InjectionProtocol:(GEHD-750,VCT)

§ Scantime: Variable(can’tspecifytime)§  Add�diagnosticdelay�tomake40sec§  Inj.duration:35sforALLpatients§ Delay: bolustriggering

weight Biphasic Injection <55 kg 20 mL (4.0mL/s) + 96 mL (3.2mL/s)

55-95 kg 25 mL (5.0mL/s) + 120 mL (4.0mL/s) >95 kg 30 mL (6.0mL/s) + 144 mL (4.8mL/s)

CTAReconstruction


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CTAReconstructionandInterpretation

§  UsesmallerFOV(Trochantertotrochanter)§  UseIterativeReconstruction§  Reconthin,overlappingimagesandreviewin3Dú  VR/MIPoverviewthenMPR,CPRú  3-5mmAxialsinA/P

§  Reconlargermatrix–1024x1024** Fleischmann D, Hallett RL, Rubin GR. JVIR 2006, 17: 3-26.

1024MatrixExamples

EfficacyofLECTAinPAD


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FontaineStage

RutherfordClassification

I Asymptomatic 0

IIa MildClaudication(>200mwalk) 1

IIb ModeratetoSevereClaudication(<200mwalk)

2(moderate)3(severe)

III IschemicRestPain 4

IV UlcerationorGangrene 5(minortissueloss)6(majortissueloss)

PADClassificationI.C

. C

LI

Detection of >50% Stenosis or Occlusion By Anatomical Region

Vessels Sens(95%CI) Spec(95%CI)

Aortoiliac 96(91-99) 98(95-99

Femoropopliteal 97(95-99) 94(85-99)

Trifurcation 95(85-99) 91(79-97)

CTA:DiagnosticPerformancevs.DSA

CTChannels Sens(95%CI) Spec(95%CI)

2-4 92(88-96) 98(95-99

16-64 97(95-98) 98(96-99)Performance

Met R et al. JAMA 2009;301:415-424

DiagnosticPerformance:64-sliceCTA

§  SymptomaticPAD:242pts,7420segments§  CTAandDSAperformed§  For>70%stenosis:

ú  SENS/SPEC96%PPV98%NPV99%ú  NosigdifferencevsDSAfindingsú  ResultssimilarinCa++vs.Non-Ca++lesions

Napoli A. Radiology. 2011 Dec 1;261(3):976–86.

TheAchilles�HeelofExtremityCTA......

PredictorsofVascularCalcification

" Aboveknee:1SeverePAD(FontaineIII-IV),Diabetes

" BelowKnee:1RenalFailure(esp.dialysis),Diabetes

" Also:2Age,cardiacdisease

" Ifheavy,significantdecreaseinSENS/SPECincalf1

1 Meyer BC Eur Radiol (2010) 20:497-505 2 Ouwendijk R. Radiology (2006) 241, 603-608

Time-ResolvedCTA-Runoff" Technique-Initial:

" timingbolusatpoplitealartery" 50mLat5mL/sec+50mLsalinechaser" 12low-doseCTAacquisitionsover30sec

" Rapid�shuttle�ofdetectorarray

" Then:standardCTArunoffprotocol

" Significantlygreaterenhancement,lessvenousoverlap

" Significantlyhigherdiagnosticconfidence" Directlyvisualizeasymmetric/delayed/

diminishedflowSommer Eur. Radiol (2010) 20: 2876-2881

ClinicalUtilityofLECTAinPAD

§  IntermittentClaudication(IC)§  CriticalLimbIschemia(CLI)


IntermittantClaudication(IC)

§  Only¼progressclinically

§  Amputationuncommon(unlessdiabetic)

§  Morelikelyilio-femoralthantrifurcationdz

ManagementofIntermittentClaudicationbyCTA

§  FontaineIIbpatients,TxdecisionsbyTASCIIcriteria

§  57/58correctTxdecision-makingbyCTAú  OneCFAstenosismissedú  29endovasc/surgTxú  29conservativemgmt

Schernthaner R, et al. AJR 2007; 189:1215-1222

§  Duration>2weeks§  restpain,tissueloss,ulcers,gangrene(TASCII)ú  FontaineIII/IV

§  HigherincidenceDM,trifurcationdisease,comorbiditiesthanIC

CriticalLimbIschemia(CLI)

CTAassessmentinCLI§  41pts,1435segments§  64-CTA§  FontaineIIb,III,IV§  2.2%segmentsnon-diagnostic

ú  notincludedincalculationú  91%infrapopsegmentsevaluable

§  For>50%stenosis:ú  Sens99% Spec98% Acc:98%

Fotiadis N, et al. Clinical Radiology 2011; 66: 945-52

ManagementDecisionsinCLI

§  28pts,FontaineIV§  64-detectorCTA§  14/28àendovascularand/orsurg.Tx§  correctdecision-makingforinterventions,amputation,andmedicalTxbasedonDSAandTxresponse

Schernthaner R, et al. AJR 2009; 192: 1416-1424

ManagementofbothICandCLIbyCTA

§  TreatedusingTASCIIguidelinesú  49conservativeTXú  87Endovascularú  38surgeryú  17hybrid

§  TxrecommendationsfromCTAsameasDSAinallbutONE

Napoli A. Radiology. 2011 Dec 1;261(3):976–86.

Examples:AtheroscleroticDisease-TherapyPlanning

ButtockClaudication–CalcifiedAorto-iliacDisease

Chang et al. JVIR. 2011 Aug 1;22(8):1131–1.

Post-TXAssessmentbyCTA

CTAforstentassessment

§  Moststentsassessable(76%)byCTAú  Gold/platinummarkersú  Motionú  Streckerstent(Tantalum):

Increasedluminaldensity2

§  Ifevaluable,sens/spec~95%forsignificantin-stentrestenosis(vs.DSA)

1 Li X, et al. Eur J Radiol 2010; 98-103 2 Strotzer, Invest. Radiol. 2001:36(11)

CTAforassessmentofcomplications

CTAforassessmentofcomplications

Willmann JK, et al. Radiology 2003; 229: 465-474.

AcuteRlegpain

Cost-EffectivenessofCTA


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CTAascost-effectivecarevsDSA

" 2005:Randomized,controlledtrial:4-DCTvsDSA1

" DxconfidenceslightlylowerwithCTA(calcifications)

" CTcost-effectiveandprovidessufficientinformationforTxplanning

" DSAcosts(564Euro)greaterthanCTA(363)

1 Kock, MC, et al. Radiology 2005. 237 (2) pp. 727-37

CTAascost-effectivecarevsMRA

§  2005:RCT-156ptsCTAvsMRA§  CTA/MRAutilitysimilar§  CTAlowerdiagnosticcosts/patient

ú  Averagecosts:$199vs$627ú  Differencefromimagingtestitself,notfromadditionalprocedures

Ouwendijk R, et al. Radiology 2005: 236: 1094-1103

CTAascost-effectivecare(vs.USandMRA)

§  2008:DIPADTrial(MulticenterRCT)§  514PADpts,randomizedtoDoppler/MRA/CTA§  CTAandMRA:

ú  significantlyhigherdiagnosticconfidenceú  lessadditionalimagingneeded

§  TotalcostslowerforCTA

Ouwendijk R, et al. AJR Am J Roentgenol. 2008;190:1349–1357

IntegratingCTAintocost-effectivecare" 2005:Randomized,controlledtrial:4-DCTvsDSA1

" DxconfidenceslightlylowerwithCTA(calcifications)" CTcost-effectiveandprovidessufficientinformationforTxplanning

" DSAcosts(564+/-210)greaterthanCTA(363+/-273)

" 2007:CorrectTXrecommendationsforI.C.2" 2009:CorrectTXrecommendationsforCLI3

1 Kock, MC, et al. Radiology 2005. 237 (2) pp. 727-37

3 Schernthaner, R, et al. AJR 2009; 192:1416-1424

2 Schernthaner, R, et al. AJR 2007; 189:1215-1222

Value-AddedInfofromCTA:GSVmapping1-2§  Pre-OpCTA:AdequateforevaluationofGSVsize1-2

ú  SENS/SPEC>90%(betterinthigh)

ú  Chargesavingsof~50Katauthorssitealone2

ú  IfGSV<2mm,thendoDopplerUS 1DeFreitas DJ, et al. J Vasc Surg 2013; 57(1): 5-55.

2Johnston WF, et al. J Vasc Surg 2012: 56(5) 1331-37.

Conclusions

§  LECTAisanaccurateandcost-effectivetoolforassessmentofvariousformsofperipheralarterialdisease

§  ImplementationofintegratedCM/scanprotocolwillimproveconsistency

§  Clinicalintegrationanduseswillcontinuetoexpand

§  Specialthanksto…..DominikFleischmann,MD

ThanksforyourAttention!


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