Part 1 Ventilation-Perfusion Lung Scan

Lung Scan Lung Scan &&

RdnRdn. . VenographyVenography

Jiraporn Jiraporn SriprapapornSriprapaporn, M.D., M.D.Nuclear MedicineNuclear MedicineSiriraj HospitalSiriraj HospitalMahidolMahidol UniversityUniversityThailandThailand

Copy Right By J Sriprapaporn

Part 1-Lung Scan_J SRIPRAPAPORN

ContentsContents--2 parts2 parts

AnatomyAnatomyPhysiologyPhysiologyMechanism Mechanism

TechniqueTechniqueIndicationsIndicationsInterpretationInterpretation

Part 2. Radionuclide Part 2. Radionuclide venographyvenography

Part 1. V/Q Lung scansPart 1. V/Q Lung scans

PART 1PART 1


RespiratoryRespiratory SystemSystem

Perfusion lung scanPerfusion lung scan:: TcTc--9999m MAAm MAA

Ventilation lung scanVentilation lung scan:: XeXe--133,133, TcTc--9999m m aerosolaerosol,, TechnegasTechnegas

MucociliaryMucociliary clearanceclearance:: TcTc--9999m HSAm HSA

Lung epithelial permeabilityLung epithelial permeability:: TcTc--9999m m DTPADTPA


AnatomyAnatomy

Right lung Right lung && left lungleft lungBronchopulmonaryBronchopulmonarysegments segments ((arteryartery,, veinvein,, && bronchusbronchus))

RightRight LungLung:: 33 lobeslobes;;RULRUL,,RMLRML,, && RLLRLLLeft LungLeft Lung:: 22 lobeslobes;; LUL LUL ((LingularLingular segmentssegments)) && LLLLLL


BronchopulmonaryBronchopulmonary SegmentsSegments

1.1. LUL LUL AnteriorAnteriorApicoApico--posteriorposteriorLingularLingular :: SuperiorSuperior

: Inferior: Inferior

2.2. LLL LLL Superior Superior Anterior basalAnterior basalLateral basalLateral basalPosterior basalPosterior basal

1.1. RUL RUL AnteriorAnteriorApicalApicalPosteriorPosterior

2.2. RMLRMLMedialMedialLateralLateral

3.3. RLL RLL Superior Superior Anterior basalAnterior basalLateral basalLateral basalPosterioPosterio basal basal


BloodBlood SupplySupply

22 SystemsSystems::

Pulmonary arteriesPulmonary arteries::95%95%

BronchialBronchial arteriesarteries:: 5%5%


PhysiologyPhysiology

AIRAIR RespiratoryRespiratory tracttract:: tracheatrachea----bronchibronchi--bronchiolesbronchioles alveolialveoliFunctionFunction:: Gas exchangeGas exchangeDistribution of Q Distribution of Q && V from apex to base is V from apex to base is unevenuneven in in the upright position the upright position ((gravity effectgravity effect))Gravity effects the distribution of both Q Gravity effects the distribution of both Q && V V ((affects affects perfusion perfusion >> ventilationventilation))

TOPBOTTOM


Ventilation & Perfusion DistributionVentilation & Perfusion Distribution

Modified from West, J.B., Ventilation/Blood Flow and Gas Exchange, Oxford, 1977.


EffectsEffects oof f GravityGravity((UprightUpright PositionPosition))

APEX VENTILATION PERFUSIONPERFUSION V/Q RATIO

BASE 1.5-2 folds 33--55 foldsfolds


PathophysiologyPathophysiology

Ventilation abnormality Ventilation abnormality redistributionredistribution of of pulmonary perfusion pulmonary perfusion HypoventilationHypoventilation reflex vasoconstriction reflex vasoconstriction hypoperfusionhypoperfusion

AcuteAcute hypoperfusionhypoperfusion rarelyrarely produces produces hypoventilationhypoventilation or minimalor minimal;; not clinically not clinically significantsignificant


LungLung ScaScann

PERFUSIONPERFUSION LUNGLUNG SCANSCAN ((QQ))TcTc--9999m m MAAMAA

VENTILATIONVENTILATION LUNGLUNG SCANSCAN ((VV))XeXe--133,133, XeXe--127,127, KrKr-- 8181mmTcTc--9999m m DTPADTPA// phytatephytate aerosolaerosolTechnegasTechnegas


IndicationsIndications of of VV//Q Q LungLung ScanScan

AAcute pulmonary embolismcute pulmonary embolism**

Pulmonary hypertensionPulmonary hypertension

PPriorrior to thoracic surgeryto thoracic surgery

RightRight--toto--left shuntleft shunt


Pulmonary EmbolismPulmonary Embolism

Most important complication of DVTMost important complication of DVTSymptomatic, Symptomatic, fatal*fatal*Asymptomatic (silent)Asymptomatic (silent)

Origin: Leg DVT (70Origin: Leg DVT (70--80%)80%)


DIAGNOSIS OF PULMONARY EMBOLISMDIAGNOSIS OF PULMONARY EMBOLISM

ClinicalsClinicals :: Inaccurate Inaccurate ((dyspneadyspnea, chest pain, , chest pain, hemoptysishemoptysis))Lab tests Lab tests :: DD--dimerdimerArterial Blood GasesArterial Blood Gases:: HypoxemiaHypoxemia,, AA--A A gradientgradientECG ECG :: Classic SClassic S11QQ33TT33 pattern pattern CXR CXR :: Normal or mild Normal or mild abnabn (*(*RR//OO otherotherdiseasesdiseases))VV//Q lung scan Q lung scan :: V/Q mismatched defectsV/Q mismatched defectsCTPA (CT Pulmonary CTPA (CT Pulmonary ArteriographyArteriography))PulmonaryPulmonary AngiographyAngiography****** Gold standardGold standardOthersOthers:: MRMRAA


ClinicalClinical DiagnosisDiagnosis oof Pf PEE

SymptomsSymptoms::Clinical TriadClinical Triad::DyspneaDyspnea(shortness of (shortness of breath)breath), , pleuriticpleuriticchest painchest pain,,hemoptysishemoptysisDyspneaDyspnea,,tachypneatachypnea,, coughcough,,chest painchest pain,, cardiac cardiac arrythmiaarrythmia,, syncopesyncope

SignsSigns::Increased HRIncreased HR,, AFAF,,RRRR,, hypotensionhypotension,,pleural rubpleural rub,, PP22

WELLS SCORE Pretest clinical probability assessment. [Wells PS, et al. Thromb Haemost. 2000 Mar;83(3):416-20.]



ChestChest RadiographRadiograph ((CCXRXR))

AtelectasisAtelectasis andand//or or parenchymalparenchymal opacity opacity (51%)(51%)Pleural effusion within the affected Pleural effusion within the affected hemithoraxhemithorax (35%)(35%)FleischnerFleischner''s signs sign ((regional regional oligemiaoligemia in the in the presence of an presence of an ipsilateralipsilateral enlarged PAenlarged PA))WestermarkWestermark''s signs sign ((local pulmonary local pulmonary oligemiaoligemia,,11%11% of of hemithoraceshemithoraces with PEwith PE))HamptonHampton’’ss humphump ((a wedgea wedge--shaped pleural shaped pleural based densitybased density,, 23%23% of of hemithoraceshemithoraces withwith PEPE))


DD--dimerdimerFibrin degradation product Fibrin degradation product

SensitivitSensitivity 90y 90--9595%, %, NOT NOT specifispecific !c !High NPVHigh NPV;; negative results negative results with with ELISA testsELISA tests effectively effectively rule out DVT or PErule out DVT or PE..

Different techniques Different results !

•The diagnostic yield of D-dimer relies on its specificity, which variesaccording to patient characteristics.

•The specificity of D-dimer in suspected PE decreases steadily withage and may reach 10% in patients above 80 years.81

•D-dimer is also more frequently elevated in patients withcancer,82,83 in hospitalized patients84 and during pregnancy.85,86

European Heart Journal 2008 29(18):2276-2315


MultidetectorMultidetector Pulmonary CTAPulmonary CTA

CTPACTPA showingshowing multiplemultiplefillingfilling defectsdefects ofof principalprincipalbranchesbranches ofof thethepulmonarypulmonary arteriesarteries,, duedue totoacuteacute andand chronicchronic PE.PE.Rad. Exposure Rad. Exposure

CTPA = 8CTPA = 8--10 10 mSvmSvV/Q = 2 V/Q = 2 mSvmSv

Sensitivity of CTA = 83 Sensitivity of CTA = 83 %, specificity = 96%, specificity = 96 %% [Stein PD & PIOPED II_NEJM 2006]


Samuel Z Goldhaber , Henri BounameauxPulmonary embolism and deep vein thrombosis The Lancet Volume 379, Issue 9828 :2012;1835 - 1846

http://dx.doi.org/10.1016/S0140-6736(11)61904-1

Figure 1 A diagnostic algorithm for clinically suspected deep Figure 1 A diagnostic algorithm for clinically suspected deep vein vein thrombosis or pulmonary embolism Use of CUS with suspected DVT thrombosis or pulmonary embolism Use of CUS with suspected DVT and of MDCT angiography with PE. CUS=compression and of MDCT angiography with PE. CUS=compression ultrasonographyultrasonography. .


Table 2. Performance of some tests or diagnostic Table 2. Performance of some tests or diagnostic algorithms to rule in or rule out PE algorithms to rule in or rule out PE

Likelihood ratio (95% CI)Likelihood ratio (95% CI)

To rule in PETo rule in PE

HighHigh--probability V/Q lung probability V/Q lung scintigraphyscintigraphy 1818··3 (103 (10··33––3232··5)5)

Positive CTAPositive CTA 2424··1 (121 (12··44––4646··7)7)

Positive proximal vein CUS of the legPositive proximal vein CUS of the leg 1616··2 (52 (5··66––4646··7)7)

To rule out PETo rule out PE

Normal or near normal ventilation perfusion lung Normal or near normal ventilation perfusion lung scintigraphyscintigraphy 00··05 (005 (0··0303––00··10)10)

Negative CTA (mainly single detector)Negative CTA (mainly single detector) 00··11 (011 (0··0606––00··19)19)

Negative CTA and proximal vein CUS of the legNegative CTA and proximal vein CUS of the leg 00··04 (004 (0··0303––00··06)06)

Negative proximal vein CUS of the legNegative proximal vein CUS of the leg 00··67 (067 (0··5050––00··89)89)

Quantitative ELISA DQuantitative ELISA D--dimerdimer assay less than 500 assay less than 500 μμgg/L/L 00··08 (008 (0··0404––00··18)18)

Goldhaber SZ 2012



PerfusionPerfusion LungLung ScanScan::PrinciplePrinciple

Tracer: TcTracer: Tc--99m MAA, particle 99m MAA, particle size=10size=10--30 u30 uMechanism: Mechanism: Capillary blockadeCapillary blockade --lodged in lodged in pprecapillaryrecapillaryarteriolesarterioles in proportion to regional blood flowin proportion to regional blood flowNumber of particlesNumber of particles::

Minimum = 100,000Minimum = 100,000Optimum = Optimum = 200,000200,000--600,000600,000

About About 1/10001/1000 ( 0.1 %)( 0.1 %) capillaricapillarieses are blocked are blocked Biological T Biological T 1/21/2 in the lungs in the lungs == 22--44 hr hr RERE systemsystem

Defects from PE

// bronchopulmonarysegments


ReducedReduced NumberNumber oof f ParticlesParticles InjectedInjected

Pediatric patientsPediatric patientsSuspected or known Suspected or known RRtt--toto--LLt shuntt shuntSevere pSevere pulmonary hypertensionulmonary hypertensionPrior pneumonectomyPrior pneumonectomySingle lung transplantSingle lung transplant100,000 to 200,000 particles100,000 to 200,000 particles


PerfusionPerfusion LungLung ScanScan::TechniquesTechniques

Dose: TcDose: Tc--99m MAA 99m MAA 33--5 5 mCimCiInjectInjection:ion: in in supinesupine positionpositionมม avoid avoid injecting via the indwelling catheter port injecting via the indwelling catheter port containing a filtercontaining a filterDo not draw blood into syringeDo not draw blood into syringe;;

““hot spotshot spots”” in in Q Q lunglung scanscan******StaticStatic planarplanar images images 66--88 viewsviews,, 500500 kctskctsSPECT imagingSPECT imaging

Critical organ = lungs


MultipleMultiple hothot spotsspots in Qin Q llungung sscancan


VentilationVentilation LungLung ScanScan::PrinciplePrinciple

Gas: most physiologic !Gas: most physiologic !ParticleParticles:s: ssmaller maller sizesize deeperdeeper!!TracersTracers

Inert gasInert gas:: 133133XeXe,, 127127XeXe,, 8181mmKrKrAerosolAerosol** (0.5 u)(0.5 u):: 9999mmTcTc--DTPADTPA// phytatephytateTechnegasTechnegas:: TcTc--9999m aerosol particle sizem aerosol particle size::0.02-0.2um


VentilationVentilation AgentsAgents

Xe-133 Xe-127 Kr-81m Tc-99m radioaerosol

Technegas/ Pertechnegas

T1/2 5.3d 36.4d 13s 6h 6h

γ energy 80 203 190 140 140

Status Gas Gas Gas Aerosol (0.5-3 um)

Gas-like (0.02-0.2 um)

Cost Low High High Low High

Before/After Q scan

B A A B B

Multiple V N N Y Y Y


TECHNEGAS TECHNEGAS vsvs PERTECHNEGASPERTECHNEGAS

Burning 99mTcO4- in a carbon

crucible at high TempUltrafine radiolabeledaerosol (0.02-0.2um)Is purged with 5%O2 + 95%argonMore penetrate alv epithelial membraneShorter residence time in the lungTbio = 6-10 min

Burning 99mTcO4- in a carbon crucible at high TempUltrafine radiolabeledaerosol (0.02-0.2um)Is purged with 100%argonLittle transalveolar or mucociliary ClearanceLonger residence time in the lungTbio = 6 hr.


VentilationVentilation LungLung ScanScan::TechniquesTechniques

Patient preparationPatient preparation:: NoneNonePatient cooperation: YesPatient cooperation: YesTechniquesTechniques::

InhalationInhalation,, upright position is upright position is preferredpreferred..


XeXe--133133 VentilationVentilation LungLung ScanScan

Single view-3 phases: Washin-Equilibrium-Washout


XeXe--133133 Ventilation Lung ScanVentilation Lung Scan

Single view, 3 phases:WashinEquilibriumWashout : most sensitive to diagnose obstructive airway disease

Xenon is fat soluble uptake in the liver refers to fatty liver.


RadioRadio--aerosolaerosolVentilationVentilation LungLung ScanScan

O2

• Imaging of multiple views

• Relatively large particles central airway deposition !


RadioRadio--aerosol aerosol Ventilation Lung ScanVentilation Lung Scan

TcTc--99m DTPA aerosol can 99m DTPA aerosol can cross alveolar capillary cross alveolar capillary membranemembrane shorter residence time as shorter residence time as compared to Tccompared to Tc--99m sulfur colloid aerosol. [half 99m sulfur colloid aerosol. [half time is about 1 hr.]time is about 1 hr.]

Only 2Only 2--10% of administered radioactivity goes to 10% of administered radioactivity goes to the lungs. [30 the lungs. [30 mCimCi 11--2 2 mCimCi]]

Central depositionCentral deposition of the radioactivity is common of the radioactivity is common inin COPD.COPD.


TECHNEGASTECHNEGAS


TechnegasTechnegas VentilationVentilation ScanScan

• Ultrafine particles

• Ideal for ventilation lung SPECT


FigureFigure 1.1. NNormalormal VV//Q Q SPECTSPECT.. usingusing TechnegasTechnegasandand 9999mTcmTc--MAAMAA arearealignedaligned andand displayeddisplayed inintransversetransverse,, coronalcoronal andandsagittalsagittal planesplanes

Roach PJ, et al SNM08


InterpretationInterpretation oof f LungLung ScanScan

1.1. Pretest clinical probabilityPretest clinical probability2.2. PerfusionPerfusion Lung Scan Lung Scan ((QQ))3.3. VentilationVentilation Lung Scan Lung Scan ((VV))4.4. CXRCXR ((within within 1212--2424 hrshrs))


NormalNormal LungLung ScanScan

Uniform distribution Uniform distribution of the radioactivityof the radioactivity

No VNo V//Q defectQ defect


1.1. NonuniformNonuniform distributiondistribution

2.2. Perfusion andPerfusion and// or ventilation or ventilation defectdefectNNonsegmentalonsegmental defectdefectSegmentalSegmental defectdefect:: wedgedwedged--shapedshaped && pleuralpleural--basedbased defectdefect

LargeLarge defectdefect:: >> 75%75% ofof segmentsegmentModerateModerate defectdefect:: 2525--75%75% ofofsegmentsegmentSmallSmall defectdefect:: << 25%25% ofof segmentsegment

AbnormalAbnormal LungLung ScanScan


V/Q Match V/Q Match vsvs MismatchMismatch

VV//Q matched defectQ matched defect:: AbnAbn both Q both Q && VV

VV//Q mismatch defectQ mismatch defect:: AbnAbn QQ,, Normal VNormal V

Pulmonary Embolism


Segmental Segmental NonNon--segmentalsegmental

Pulmonary embolismPulmonary embolismPulmonary infarctPulmonary infarct

TumorsTumorsPleuralPleural effusioneffusionCardiomegalyCardiomegalyMediastinalMediastinal oror hilarhilaradenopathyadenopathyPneumoniaPneumoniaBullaeBullaeMetalMetal artifactsartifacts


NonNon--PEPE DiseasesDiseases//ConditionsConditions

PatchyPatchy distributiondistributionNonsegmentalNonsegmental defectdefectMatchedMatched VV//Q Q defectdefect((ss))CausesCauses egeg.. metallicmetallic artifactartifact,, enlargedenlarged LNLN,,tumortumor,, heartheart,, pneumoniapneumonia,, effusioneffusion


VV//Q Q MatchedMatched AbnormalitiesAbnormalities

COPDCOPDBlebsBlebs,, bullaebullaePulmonary edemaPulmonary edema,, CHFCHFPleural effusionPleural effusionAsthmaAsthmaPulmonary traumaPulmonary traumaMucous plugMucous plugBronchogenicBronchogenic CACA


V/Q Mismatches: CausesV/Q Mismatches: Causes

Acute PEAcute PEPrevious PEPrevious PEBronchogenicBronchogenic carcinomacarcinomaVasculitisVasculitisPrevious radiation therapyPrevious radiation therapyPulmonary vascular Pulmonary vascular anormaliesanormalies


InterpretationInterpretation oof f AcuteAcute PPEE

““PIOPED CRITERIAPIOPED CRITERIA””NormalNormal RR//O significant O significant PEPE !!-- likelihood of likelihood of PE < 5%PE < 5%Very low probability: Very low probability: < 10%< 10%LowLow probabilityprobability :: << 20%20%IntermediateIntermediate :: 2020--80%80%HighHigh probabilityprobability:: >> 80%.80%. AtAt least least 22 large large segmental mismatched Vsegmental mismatched V//Q defectsQ defects,,negative CXRnegative CXR

PIOPED " The Prospective Investigation of Pulmonary Embolism Diagnosis "


PIOPEDPIOPED

"" The Prospective Investigation The Prospective Investigation ofof Pulmonary Pulmonary EmbolismEmbolism Diagnosis Diagnosis ““Used pulmonary angiogram as a gold Used pulmonary angiogram as a gold standard.standard.

TheThe criteria were developed in late criteria were developed in late 19831983The largest study of accuracy of lung scan in The largest study of accuracy of lung scan in

the the DxDx of acute PEof acute PE66 medical centers in Umedical centers in U..SS..AA..

PIOPED II CTA PIOPED III MRA

PIOPED I V/Q Lung scan


Original PIOPED CriteriaOriginal PIOPED CriteriaHigh Probability:High Probability:

> 2 large segmental perfusion defects> 2 large segmental perfusion defects without corresponding ventilation or without corresponding ventilation or roentgenographicroentgenographic abnormalities or substantially larger than either matching ventabnormalities or substantially larger than either matching ventilation ilation or CXR abnormality. or CXR abnormality. > 2 moderate segmental perfusion defects without corresponding v> 2 moderate segmental perfusion defects without corresponding ventilation or entilation or roentgenographicroentgenographic abnormalities and 1 large mismatched segmental defect. abnormalities and 1 large mismatched segmental defect. > 4 moderate segmental perfusion defects without ventilation or > 4 moderate segmental perfusion defects without ventilation or CXR abnormalities. CXR abnormalities.

Intermediate probability (indeterminate):Intermediate probability (indeterminate):Not falling into normal, veryNot falling into normal, very--lowlow--, low, low--, or high, or high--probability categories. probability categories. Borderline high or borderline low. Borderline high or borderline low. Difficult to categorize as low or high. Difficult to categorize as low or high.

Low probability:Low probability:NonsegmentalNonsegmental perfusion defects perfusion defects Single moderate mismatched segmental perfusion defect with normaSingle moderate mismatched segmental perfusion defect with normal CXR l CXR Any perfusion defect with a substantially larger CXR abnormalityAny perfusion defect with a substantially larger CXR abnormality. . Large or moderate segmental perfusion defects involving no more Large or moderate segmental perfusion defects involving no more than 4 segments in than 4 segments in 1 lung and no more than 3 segments in 1 lung region with matchin1 lung and no more than 3 segments in 1 lung region with matching ventilation defects g ventilation defects either equal to or larger in size and chest roentgenogram eithereither equal to or larger in size and chest roentgenogram either normal or with normal or with abnormalities substantially smaller than perfusion defects. abnormalities substantially smaller than perfusion defects. >3 small segmental perfusion defects with a normal >3 small segmental perfusion defects with a normal

Very low probability:Very low probability:<3 small segmental perfusion with a normal CXR.<3 small segmental perfusion with a normal CXR.

Normal:Normal:No perfusion defects No perfusion defects NOTE:CXR=chest roentgenogram. NOTE:CXR=chest roentgenogram. JAMA 1990


VV//Q Q Lung ScanLung Scanfforor DetectionDetection oof Pf PEE oon Pn PAGAG

ProbabilitProbability y BielloBiello McNeilMcNeil PIOPED PIOPED BielloBiello McNeilMcNeil PIOPEDPIOPED

HighHigh 5757 5353 4141 9090 9191 9797HighHigh//IntermInterm.. 6969 6161 8282 7575 7979 5252HighHigh//IntermInterm.. 9797 9898 9898 5151 5151 1010

//LowLow

Sensitivity Specificity

[Worsley DF et al. Radiologic Clinics of N America 1993]

NB. High number of intermediate prob., 39% of the total populationstudied (364 of 931), while 68% of the subjects were inpatients.[Freeman LM SNM 2008]

PPV

81%


V/Q Lung ScanV/Q Lung Scan

High High probprobNPV = 91%NPV = 91%PPV = 81% for all types of PtsPPV = 81% for all types of Pts

PPV = 91% for Pts without prior PEPPV = 91% for Pts without prior PEPPV = 74% for Pts with prior PEPPV = 74% for Pts with prior PE

Low Low probprobNPV = 84% NPV = 84% Low Low probprob VQ VQ ++veve PE in 15% of Pts.PE in 15% of Pts.Thus, should not Thus, should not misinterpretemisinterprete lowlow--probprob lung lung

scan as R/O PEscan as R/O PE


PPVPPV oof Vf V//Q Q LungLung ScanScaniin n DiagnosisDiagnosis oof Pf PEE

Clinical Probability

Scan Category 80-100% 20-79% 0-19%

High 95% 85% 83%

Intermediate 71% 29% 14%

Low 43% 16% 4%

Normal/NN 0% 7% 2%

[PIOPED JAMA 1990, Sostman HD Radiology 1994]


Ventilation-Perfusion Scintigraphy in thePIOPED Study. Part II. Evaluation of theScintigraphic Criteria and Interpretations

we recommend that 3 criteria should be reconsidered:1. A single moderate perfusion defect is appropriately

categonzed as intermediate, rather than as lowprobability.

2. Extensive matched V/Q abnormalitiesare appropriatefor low probability, provided that the CXR is dear.Single-matched defect may be better categonzed asintermediate probability. [small number of cases].

3. 2 segmental mismatches may not be the optimumthreshdd for high probability, and in some casesshould be considered for intermediate probability.[small number of cases]

Gottschalk A, et al. J NucIMed1993;34:1119-1126

Revised PIOPED V/Q Scan Criteria


Ventilation-Perfusion Scintigraphy in thePIOPED Study. Part II. Evaluation of theScintigraphic Criteria and Interpretations

Gottschalk A, et al. J Nucl Med 1993;34:1119-1126 PMID: 8315488


Revised paper_by Sostman Radiology 1994


AIM:AIM:To compare original, revised PIOPED & gestalt To compare original, revised PIOPED & gestalt interpretation.interpretation.

RESULTS:The gestalt probability estimate was the most accurate forassessing the likelihood of PE. [area under the ROC curve0.836]The revised PIOPED criteria (area under the ROC curve =0.753) were more accurate than the original PIOPEDcriteria.

CONCLUSION:The revised PIOPED criteria are more accurate than theoriginal PIOPED criteria.Experienced readers of lung scans can achieve highestaccuracy

Sostman HD Radiology 1994; 193:103-107


DefDef:: a matching perfusiona matching perfusion,, ventilationventilation,,and CXR abnormalityand CXR abnormality

UpperUpper && middle lung zones middle lung zones ==Very lVery lowow probprobof PE of PE (4%)(4%) [[Stein PD & Gottschalk A. RadioGraphics January 2000:20;99-105]]

Lower Lower lung zonelung zone == Intermediate Intermediate probprob of PE of PE (33%)(33%)

[[WorsleyWorsley DFDF,, AlaviAlavi AA.. J J NuclNucl MedMed 1995;1995; 36:36: 23802380--23872387WorsleyWorsley DFDF,, et alet al.. J J NuclNucl MedMed 1993;1993; 34:34: 18511851--1853]1853]

TRIPLETRIPLE MATCHMATCH


""Stripe SignStripe Sign"" == A thin line A thin line ((stripestripe)) of activity of activity ((perfusionperfusion))at the pleural surface of a Q defectat the pleural surface of a Q defect..

The finding is associated is likely related to The finding is associated is likely related to spared perfusion in the cortex of the lungspared perfusion in the cortex of the lung[[SostmanSostman HDHD,, GottschalkGottschalk AA.. Radiology Radiology 19921992 ]]

""Stripe SignStripe Sign"" is suggested to is suggested to indicateindicate very very lowlow probabilityprobability == 7%7% of lung zones with the of lung zones with the stripe sign stripe sign had PEhad PE present on PAG in the present on PAG in the PIOPED study PIOPED study [[GottschalkGottschalk AA,, et alet al.. J J NuclNucl MedMed 1993]1993]

STRIPESTRIPE SIGNSIGN


Low Low probprob misleading due to sig. PE misleading due to sig. PE prevprev

VV//Q Lung Scan ClassificationQ Lung Scan Classification

Stein PD & Gottschalk A. RadioGraphics January 2000:20;99-105


785§6Stripe sign

427‡1Triple matched defect in the upper or middle lung zone

168†11-3 small segmental Q defects

330*1Matched V/Q defects in 2 or 3 zones of a single lung (normal radiograph)

840*3Q defect smaller than corresponding radiographic defect

8103*8Nonsegmental perfusion abnormality

PPV(%)No. of Patients,

Lungs, or Lung Zones or Regions

No. of Cases of PE

Criterion

*Individual lungs were evaluated. †Patients were evaluated.‡Lung zones were evaluated §Lung regions were evaluated.

CriteriaCriteria forfor VeryVery--llowow ProbabilityProbabilityInterpretationInterpretation ofof VQVQ LungLung ScansScans

Stein PD & Gottschalk A. RadioGraphics January 2000:20;99-105

PPV < 10 %


Causes of Decreased Perfusion Causes of Decreased Perfusion to One Lungto One Lung

Pulmonary agenesis or Pulmonary agenesis or stenosisstenosisSwyerSwyer--James syndromeJames syndromeEmbolusEmbolusPneumothoraxPneumothoraxMassive pleural effusionMassive pleural effusionMediastinalMediastinal fibrosisfibrosisTumorTumor


TypicalTypical ScintigraphicScintigraphicFindingsFindings ForFor PEPE

Multiple segmental Multiple segmental perfusion defectsperfusion defectsNormal ventilationNormal ventilationUsually normal Usually normal CXRCXR

““MismatchMismatcheded VV//Q Q defectsdefects””


ResolutionResolution ofof Q Q DefectDefectssiin n AcuteAcute PEPE

First First 22 weeksweeks rapidrapid resolutionresolution,, then slower then slower over the next over the next 33 MoMo33%33% of of PtsPts with major emboli have perfusion with major emboli have perfusion defects beyond defects beyond 1212 MoMoThe resolution is slower with increasing age The resolution is slower with increasing age &&in the presence of cardiovascular disease in the presence of cardiovascular disease ((Tom Tom && Wagner Wagner 1967)1967)15-35% of Pts have recurrent PE with in the first yr.


ResolutionResolution oof f PerfusionPerfusion DefectDefect

Q Defect 2 Wk 3 Wk 4 Wk Recover

4 Mo

Improve

4 Mo

Small 40% 67% 75%

Moderate 30% 38% 51%

Severe 20% 20% 70%

Note: Small: <15%, Moderate 15-30%, Severe >30% reduced pulmonary blood flow (Tom & Wagner 1967)


PPulmonaryulmonary EEmbolismmbolism::Before & After AnticoagulantBefore & After Anticoagulant RxRx


AcuteAcute PulmonaryPulmonary EmbolismEmbolism

PerfusionPerfusion--Ventilation lung scan Ventilation lung scan ******Multiple mismatched VMultiple mismatched V//Q defects Q defects ((segmentalsegmental),),No radiographic abnormalityNo radiographic abnormalityIncreasing noIncreasing no.. of defects of defects increasingincreasingspecificityspecificityPulmonary Pulmonary angiographyangiography is the gold standardis the gold standard..VV//Q scan cannot Q scan cannot DDxDDx acute from chronic PEacute from chronic PE,, so so FF//U scan to evaluate the lung status post Rx U scan to evaluate the lung status post Rx ****** ((Baseline for the new episodeBaseline for the new episode,, if anyif any))


PulmonaryPulmonary HypertensionHypertensionDef: Mean Def: Mean pulmpulm arterial P > 25 mmHgarterial P > 25 mmHgCauses of PHT: PPHT (idiopathic, Causes of PHT: PPHT (idiopathic, chrchr thromboembolicthromboembolic, left , left heart disease, heart disease, pulmpulm parenchymalparenchymal disease)disease)PrimaryPrimary PHTPHT

Idiopathic PHTIdiopathic PHT,, small small vvvv..,, obliterativeobliterativeDxDx by exclusion criteriaby exclusion criteriaLung scanLung scan:: NonsegmentalNonsegmental patchy Q defect patchy Q defect

ThromboembolicThromboembolic PHTPHTLarge Large vvvvTTreatablereatable

VV//Q lung scan canQ lung scan can help help DxDx thromboembolic PHT thromboembolic PHT (found < (found < 5% of PHT cases)5% of PHT cases)

SenSen > CTA;> CTA; sensen > 96%, spec 95%, accuracy 95%> 96%, spec 95%, accuracy 95%


PE in ThailandPE in Thailand

PalwatwichaiPalwatwichai AA,, et alet al.. J J MedMed AssocAssoc ThaiThai.. 20002000

Retrospective review oRetrospective review of 49f 49 patients patients diagnoseddiagnosedas PE in Phramongkutklao as PE in Phramongkutklao HospHosp.. betweebetween n 1994 and 19981994 and 1998The mortality rate The mortality rate wawas 10%.s 10%.Chronic Chronic thromboembolicthromboembolic pulmonary HT was pulmonary HT was diagnosed idiagnosed in 12%n 12% of the patientsof the patientsHighHigh--probability VQ lung scanprobability VQ lung scan and and DVTDVT were were demonstrated idemonstrated in 93%n 93% anand 55%d 55%,, respectivelyrespectively..


PE in ThailandPE in Thailand

Prevalence of pulmonary embolism in Prevalence of pulmonary embolism in patients with deep venous thrombosis patients with deep venous thrombosis ((MangkharakMangkharak et al.)et al.)

Prospective study of 48 cases with proven Prospective study of 48 cases with proven leg DTVleg DTV

1212 cases cases (25%)(25%) had highhad high--probprob lung scanlung scan77 cases cases (58%)(58%) -- No No respresp symptomsymptom((asymptomaticasymptomatic PEPE))55 cases cases (42%)(42%) -- with with respresp symptom symptom ((symptomatic PEsymptomatic PE))


VV//Q Q LungLung ScanScan fforor DxDx PEPE

ADVANTAGES VS DISADVANTAGESADVANTAGES VS DISADVANTAGES

SimpleSimple,, noninvasivenoninvasive,,safesafe,, and economicaland economicalHigh specificityHigh specificity (98%)(98%)espesp.. increasing noincreasing no.. of of defects defects The usefulness is well The usefulness is well documenteddocumented..

Not widely availableNot widely availableMinimal radiationMinimal radiationLow sensitivity Low sensitivity (41%)(41%)Limitation in Limitation in abnabn CXRCXRVV//Q scan cannot Q scan cannot DDxDDxacute from chronic PE acute from chronic PE

needneed FF//U scanU scan


IsIs FollowFollow--upup LungLung ScanScan UsefulUseful ??

Because resolution of Q defect may not be completeBecause resolution of Q defect may not be complete,,depending on defect sizedepending on defect size,, durationduration,, also Ptalso Pt’’s age s age &&underlying cardiovascular diseases underlying cardiovascular diseases ((Tom Tom && Wagner Wagner 1967)1967) [33%[33% of of PtsPts with major emboli have perfusion with major emboli have perfusion defects beyond defects beyond 1212 MoMo]]And And 1515--35%35% of of PtsPts have recurrent PE with in the first have recurrent PE with in the first yryr..Since VQ lung scan cannot Since VQ lung scan cannot DDxDDx new or old emboli new or old emboli FF//U VU V//Q scan at least at Q scan at least at 33 MoMo is useful as the is useful as the baseline for the next episodebaseline for the next episode.. ((slower resolution slower resolution occurs after occurs after 33 MoMo))

That’s why we need F/U lung scan ?



ApplicationsApplications ffororNonNon--embolicembolic LungLung DisordersDisorders

RRightight--toto--lefleftt shunt shunt ******Prior thoracic surgeryPrior thoracic surgery:: Lung cancerLung cancer,,Other lung diseasesOther lung diseasesLung transplantationLung transplantationInflammatory lung diseasesInflammatory lung diseasesOthersOthers


RRightight--toto--LLefteft SShunthunt

Intracardiac shuntIntrapulmonary shunt

Through Through pulmpulm AV fistulasAV fistulasTiny Tiny abnabn,, difficult to demonstrate by difficult to demonstrate by angiographyangiographyProduce Produce hypoxemiahypoxemia,, && assoasso with with significant significant intraopintraop.. && POPO.. risk risk Relative CRelative C//I to liver transplantI to liver transplant


RightRight--toto--left Shuntleft ShuntSystemic Circulation


Presence of Presence of TcTc--9999m m MAA in the systemic MAA in the systemic circulationcirculation;; brain brain &&kidneyskidneys

TechniqueTechnique:: Limited MAA Limited MAA particlesparticles..

LungLung ScanScan iin n RtRt--toto--LLt t ShuntShunt


PriorPrior ThoracicThoracic SurgerySurgery

Quantitative lung function study Quantitative lung function study Geometric mean: Geometric mean: √√CCANTANT . . CC POSTPOST

Equivocal lung function test Equivocal lung function test ((egeg. FEV1, FVC). FEV1, FVC)

ToTo evaluate regional lung function and evaluate regional lung function and predict residual lung function post surgical predict residual lung function post surgical resectionresection

Lung cancerLung cancerOther lung Other lung diseasesdiseases


QuantitativeQuantitativeLungLung FunctionFunction StudyStudy

FIGURE 12FIGURE 12.. Quantitative Quantitative perfusion scan perfusion scan Large perfusion defect from Large perfusion defect from tumor on posterior image tumor on posterior image ((arrowarrow).).LLeft lung contributes eft lung contributes 30.6%30.6%and right lung and right lung 69.4%69.4% of total of total pulmonary function pulmonary function ((arrowheadsarrowheads).).HenceHence,, it is anticipated that it is anticipated that removal of left lung will removal of left lung will result in decrease of result in decrease of approximately approximately 30%30% of total of total pulmonary functionpulmonary function..

JNMT March 2009 vol. 37 no. 1 1-13


WellsWells PSPS.. PulmonaryPulmonary embolismembolism::a a clinicianclinician''s s perspectiveperspective..

SeminSemin NuclNucl MedMed.. 20082008 NovNov;38(6):404;38(6):404--11.11.

....... Diagnostic strategies should include pretest clinicalprobability,D-dimer assays, and imaging tests.

Approaches that use CTPA or V/Q scanning appear equally safe, buteach approach hasadvantages and disadvantages that should beappreciated to provide the best care.

Importantly, patients at low risk with a negative D-dimer can avoidimaging tests

V/Q scanningmay be more appropriate in premenopausal women,in those with renal dysfunctionor diabetes, in those with knowncontrast allergies, and perhaps in patients withknown familyhistory of breast cancer.


Prof Leonard M. FreemanMontefiore Medical CenterAlbert Einstein College of MedicineBronx, New York

•VQ Scan as a primary examination•VQ scan as a F/U study

1/4


VQVQ ScanScan asas a a primaryprimary examinationexamination

DrawbacksDrawbacks withwith usingusing MDCTAMDCTA forfor SuspectedSuspected1.1. ContrastContrast--relatedrelated

ContrastContrast AllergyAllergyNephrotoxicityNephrotoxicity

2.2. InstrumentInstrument--relatedrelatedClaustrophobiaClaustrophobiaObesityObesity

3.3. RadiationRadiation exposureexposure--relatedrelatedChildrenChildrenPregnantPregnant womenwomen--fetusfetusYoungYoung womenwomen--breastbreast tissuetissue

2/4


VQVQ scanscan asas a Fa F//U U studystudyIt is most beneficial to follow all positive CT studies with abaseline V/Q study for the purpose of long-term follow-up.

DDx old vs new clot facilitate such importantdecisions.

A baseline V/Q study should be routinely performed inpatients with DVT since the incidence of silent PE is about38% or greater.

In a DVT patient who has been anticoagulated and,subsequently, presents with suspected PE judge whetherthe embolus has occurred before or after the start of theanticoagulation.

If the PE was present at the time of DVT diagnosis,continuation of anticoagulant therapy will suffice. (besufficient)If the latter IVC ‘‘umbrella’’ procedure may bewarranted. 3/4


ConclusionConclusion

1. It is the responsibility of the imaging physician to beknowledgeable about the relative value and the benefit-to-riskratio of each procedure to properly advise the referring physician.

2. Most medical centers do not offer ‘‘after hours’’ nuclear medicineservices on nights and weekends while there is 24-h readyavailability of CT scanners prefer MDCT

3. It is my belief that a plain CXR can be useful to determine which procedure should be performed* Normal or near-normal CXR V/Q scan* Abnormal CXR MDCTA.

4. It also is the inherent responsibility of all radiologists and NMphysicians to educate our referring clinicians about the excessiveradiation exposure associated with MDCTA, particularly to thefemale breast.

4/4


SummarySummaryMultidetector CTA and V/Q lung scintigraphy are bothexcellent imaging examinations to evaluate patients withsuspected PE.Because of the much greater radiation exposure,particularly to the female breast, associated with CTA, itis desirable to use V/Q imaging when possible.The major problem causing difficulty in interpreting V/Q studies is underlying pulmonary disease, such aspneumonia, significant atelectasis, pleural effusions, andchronic obstructive lung disease. If abnormal CXR,directing to a CTA.Most importantly, it is the responsibility of the imagingphysician to be knowledgeable about the relative valueand the benefit-to-risk ratio of each procedure toproperly advises the referring physician.


WellWell’’ss CriteriaCriteria forfor PEPE:: Program CalculationProgram Calculation

httphttp://://wwwwww..mdcalcmdcalc..comcom//wellswells--criteriacriteria--forfor--pulmonarypulmonary--embolismembolism--pepe


Suggested ReadingSuggested Reading

Essentials of Nuclear Medicine ImagingEssentials of Nuclear Medicine Imaging

The Requisites: Nuclear MedicineThe Requisites: Nuclear Medicine


Lung Scan v4_SNM Guideline Mar 2012

Continue for part 2.Continue for part 2.

Radionuclide Radionuclide VenographyVenography

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Part 1 Ventilation-Perfusion Lung Scan

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