coronary cta darrin johnson, md april 20 th, 2005 radiology of huntsville

Coronary CTACoronary CTA

Darrin Johnson, MDDarrin Johnson, MDApril 20April 20thth, 2005, 2005

Radiology of HuntsvilleRadiology of Huntsville

What is Coronary What is Coronary CTA?CTA?

• Coronary CTA is a non-invasive minimal risk Coronary CTA is a non-invasive minimal risk procedure to directly visualize the coronary procedure to directly visualize the coronary arteriesarteries– It is It is NOTNOT calcium scoring calcium scoring– It involves administration of contrastIt involves administration of contrast

• It allows visualization of the coronary arteries It allows visualization of the coronary arteries similar to a cardiac catheterization with additional similar to a cardiac catheterization with additional information about the WALL of the artery and information about the WALL of the artery and composition of plaque (calcified or non-calcified)composition of plaque (calcified or non-calcified)

Not your standard CT Angio of the Not your standard CT Angio of the ChestChest

• Requires some patient prepRequires some patient prep

• Beta Blockers mandatoryBeta Blockers mandatory

• Sublingual nitro on table helpfulSublingual nitro on table helpful

• Technically more labor intensiveTechnically more labor intensive

Patient PreparationPatient Preparation

• No Caffeine for 12 hours prior to examNo Caffeine for 12 hours prior to exam• Everyone gets Beta-Blockers Everyone gets Beta-Blockers (Verapamil can be (Verapamil can be

substituted)substituted)

• IV Heplock IV Heplock BEFOREBEFORE they get into the room they get into the room

• Antecubital only, left better than right, Antecubital only, left better than right, 18g-20g18g-20g

Beta-Blocker ProtocolsBeta-Blocker Protocols

• Metoprolol 100mgMetoprolol 100mg one hour before one hour before study.study.

• IF HR<62bpm DoneIF HR<62bpm Done• If HR 62-70bpm 2If HR 62-70bpm 2ndnd Dose Metoprolol 50mg Dose Metoprolol 50mg

and and wait 30 minwait 30 min• If HR >70bpm 2If HR >70bpm 2ndnd Dose Metoprolol 100mg Dose Metoprolol 100mg

and and wait 30minwait 30min

• History of asthma switch to History of asthma switch to Verapamil Verapamil 240mg240mg one hour before. one hour before.

Goal Heart RateGoal Heart Rate

• <60 bpm makes us happy<60 bpm makes us happy

• 60-75bpm we can do if they have a 60-75bpm we can do if they have a regular rhythm.regular rhythm.

•Acceptable images, but you will have to Acceptable images, but you will have to work harder for them.work harder for them.

Medications at Scan TimeMedications at Scan Time

• Oxygen (2L NC)Oxygen (2L NC)

• Nitro Spray (1/150gr sl- one full Nitro Spray (1/150gr sl- one full plunger)plunger)

• ?Sedation (Valium 10mg one hour ?Sedation (Valium 10mg one hour before)before)

– If HR>75 and fail max Beta-BlockersIf HR>75 and fail max Beta-Blockers

Nitro ContraindicationsNitro Contraindications

• AllergyAllergy

• Viagra and Like medsViagra and Like meds

ContraindicationsContraindications

• Atrial FibrillationAtrial Fibrillation• TachycardiaTachycardia• Beta Blockade ContraindicationBeta Blockade Contraindication

– Can use calcium channel blocker (Verapamil Can use calcium channel blocker (Verapamil 240mg one hour before, can repeat once)240mg one hour before, can repeat once)

• Acute chest painAcute chest pain• Heart BlockHeart Block• Renal Failure (Creat>1.5)Renal Failure (Creat>1.5)• Contrast AllergyContrast Allergy• NO pacemakersNO pacemakers

What about Pacemakers?What about Pacemakers?

• The real problem is artifact from the right atrial The real problem is artifact from the right atrial appendage lead.appendage lead.

• Presence of a cardiologist to dial down the heart Presence of a cardiologist to dial down the heart rate?rate?

Coronary CTA: Why do it?Coronary CTA: Why do it?

• In 2001, 3.51 million cardiac caths performedIn 2001, 3.51 million cardiac caths performed• Only 9% were emergentOnly 9% were emergent• 1.7 Million caths for diagnosis only (30-40% negative)1.7 Million caths for diagnosis only (30-40% negative)• Every year 150,000 Americans die of sudden death Every year 150,000 Americans die of sudden death

related to acute coronary syndrome and smaller related to acute coronary syndrome and smaller number experience MI as first sign of CADnumber experience MI as first sign of CAD

• What is needed is a non-invasive, minimal-risk, What is needed is a non-invasive, minimal-risk, outpatient procedure to detect early signs of CAD so outpatient procedure to detect early signs of CAD so that risk factor modification and medical management that risk factor modification and medical management can be initiated early enough to reduce the number of can be initiated early enough to reduce the number of patients experiencing acute coronary syndromes.patients experiencing acute coronary syndromes.

Coronary AtherosclerosisCoronary Atherosclerosis

Intimal ThickeningIntimal Thickening

AtheromaRupture/Erosion

HemorrhageHealing

Thrombus

Occlusion

Fibrocalcified Plaque

StenosisWall Changes

Calcified Nodule

Stress Test

Cath

Coronary CTA

Patient Selection: Who should Get it?Patient Selection: Who should Get it?

• A Traditional risk factor should be required A Traditional risk factor should be required to have a coronary CTA.to have a coronary CTA.

Primary CAD Risk FactorsPrimary CAD Risk Factors

• Cigarette SmokingCigarette Smoking

• Hypertension ( >140/90 mmHg )Hypertension ( >140/90 mmHg )

• Elevated LDL ( >130 mg/dl )Elevated LDL ( >130 mg/dl )

• Low HDL ( < 40 mg/dl )Low HDL ( < 40 mg/dl )

• Diabetes MellitusDiabetes Mellitus

• Family HistoryFamily History

Non-Traditional Risk FactorsNon-Traditional Risk Factors

• Homocysteine levelsHomocysteine levels

• C-reactive proteinC-reactive protein

• Small LDL particle sizeSmall LDL particle size

• Inherited SyndromesInherited Syndromes

What about Symptomatic What about Symptomatic Patients?Patients?

• Initially, as an outpatient procedure, we do Initially, as an outpatient procedure, we do not want patients with acute, undiagnosed not want patients with acute, undiagnosed classic chest pain in our office.classic chest pain in our office.

• Stable anginaStable angina under a physician’s care and under a physician’s care and unexplained unexplained atypical chest painatypical chest pain is OK. is OK.

When do I order Coronary CTA?When do I order Coronary CTA?

• Asymptomatic patient with traditional risk Asymptomatic patient with traditional risk factors.factors.

• Strong positive family history.Strong positive family history.• Examine bypass grafts and stents.Examine bypass grafts and stents.• Prior to cath in patients with atypical Prior to cath in patients with atypical

symptoms.symptoms.• If HU units are able to be measured- follow up?If HU units are able to be measured- follow up?• Before stress nuc med, treadmill or stress Before stress nuc med, treadmill or stress

echo. These tests measure flow reserve and echo. These tests measure flow reserve and will be normal in patients with soft plaque and will be normal in patients with soft plaque and no stenosis. Also higher rate of false positives no stenosis. Also higher rate of false positives with these exams cause unnecessary cath’s.with these exams cause unnecessary cath’s.

• Clarify the equivocal stress test.Clarify the equivocal stress test.

Business related IssuesBusiness related Issues

• Potential CPT codesPotential CPT codes•71275 CT angio chest71275 CT angio chest

•71260 CT Chest71260 CT Chest

• No ICD-9 code for the work up of No ICD-9 code for the work up of asymptomatic patient with risk asymptomatic patient with risk factorsfactors

Business related IssuesBusiness related Issues

• Potential ICD-9 CodesPotential ICD-9 Codes 786.50786.50 chest pain, unspecified chest pain, unspecified 786.51786.51 precordial pain precordial pain 786.52786.52 painful respiration painful respiration 786.59786.59 chest discomfort/tightness chest discomfort/tightness 786.7786.7 Abnormal chest sounds Abnormal chest sounds

How Do They Compare?How Do They Compare?

Images by GE CT-AImages by GE CT-A

• Color composite Color composite image (not intended image (not intended as diagnostic tool)as diagnostic tool)

• Used here to show Used here to show global picture and to global picture and to focus on two areas of focus on two areas of interest:interest:– Stent in the RCA which Stent in the RCA which

clinically has remained clinically has remained patentpatent

– Area of apparent Area of apparent disease in LAD at disease in LAD at bifurcation of diagonalbifurcation of diagonal

Stent in RCA

LAD

CTA

RCA and StentRCA and Stent

•Stent well delineated by CT-A•Note mild proximal narrowing•Seen with difficulty on fluoro prior to angiography

Stent

Fluoroscopy

Angiography

LAD by CTALAD by CTA

• Image appears to Image appears to show several areas of show several areas of calcification in vessel calcification in vessel (blue arrows)(blue arrows)

• Lesion of borderline Lesion of borderline significance appears significance appears in proximal LAD in proximal LAD (green circle)(green circle)

• Moderate disease at Moderate disease at bifurcation of left main bifurcation of left main (yellow circle)(yellow circle)

RAO angiogram

How Does Angiogram How Does Angiogram Compare?Compare?

Angiogram does not clearly show disease in the same areas

LAO angiogram

Invasive

Left Main

Ostial LADProximal LAD

Bifurcation

Noninvasive

IVUSIVUSLeft Main - NL

Ostial LAD - 40%

Proximal LAD - 30%Bifurcation - 50%

Pressure wire/fractional flow Pressure wire/fractional flow reservereserve

• Pressure wire Pressure wire confirms absence of confirms absence of pressure gradient in pressure gradient in proximal LADproximal LAD

• With adenosine With adenosine injection, pressure injection, pressure separation confirms separation confirms bifurcation lesion of bifurcation lesion of moderate severity moderate severity (FFR = 0.76)(FFR = 0.76)

• Thus pressure wire Thus pressure wire confirms physiologic confirms physiologic importance of importance of bifurcation lesionbifurcation lesionProximal LAD

Post bifurcation

Aorta

Distal

CCTA vs Invasive CCTA vs Invasive AngiographyAngiography

• Good IVUS and Good IVUS and pressure wire pressure wire correlation with CT-A correlation with CT-A

• Invasive coronary Invasive coronary angiography missed angiography missed most of the important most of the important disease disease

• IVUS and pressure IVUS and pressure wire are highly wire are highly invasive while CT-A is invasive while CT-A is noninvasivenoninvasive

Teaching PointsTeaching Points

11. “The current gold standard for . “The current gold standard for detecting coronary artery stenosis detecting coronary artery stenosis is coronary catheterization, but it is is coronary catheterization, but it is not a very shiny gold.”not a very shiny gold.”

22. Cath Correlation without IVUS is . Cath Correlation without IVUS is a poor tool to evaluate Coronary a poor tool to evaluate Coronary CTA!!!CTA!!!

Stenosis Detection >50%Stenosis Detection >50%

• Nieman, et.al. Circulation 2002; 106: Nieman, et.al. Circulation 2002; 106: 2051-2054.2051-2054.

• 16 slice CT, 12 for cardiac.16 slice CT, 12 for cardiac.

• Sensitivity = 95%Sensitivity = 95%

• Specificity = 86%Specificity = 86%

• PPV = 80%PPV = 80%

• NPV = 97%NPV = 97%

Stenosis Detection >50%Stenosis Detection >50%

• Ropers, et.al. Circulation 2003.Ropers, et.al. Circulation 2003.

• 16 slice CT, 12 for cardiac, slice 16 slice CT, 12 for cardiac, slice thickness .75mm.thickness .75mm.

• Excluded 12% of vascular segments.Excluded 12% of vascular segments.

• Sensitivity = 92%Sensitivity = 92%

• Specificity = 93%Specificity = 93%

• PPV = 79%PPV = 79%

• NPV = 97%NPV = 97%

Diagnostic Accuracy of Noninvasive Coronary Diagnostic Accuracy of Noninvasive Coronary Imaging Using 16-Detector Slice Spiral CT with Imaging Using 16-Detector Slice Spiral CT with 188ms Temporal Resolution188ms Temporal Resolution

• N=72N=72• 51% received beta-blockers for HR>6551% received beta-blockers for HR>65• 62/936 segments nondiagnostic but all segments included 62/936 segments nondiagnostic but all segments included

in the analysisin the analysis• Compared with cathCompared with cath• 117 relevant lesions (diameter stenosis 50%)117 relevant lesions (diameter stenosis 50%)• Sensitivity = 82%Sensitivity = 82%• Specificity = 98%Specificity = 98%• PPV = 87%PPV = 87%• NPV = 97%NPV = 97%• Correct clinical diagnosis of significant CAD = 90%Correct clinical diagnosis of significant CAD = 90%• All stenoses detected by MDCT = 72%All stenoses detected by MDCT = 72%

Kuettner A, Beck T, Drosch T, et.al. JACC, 4 Jan 2005; (45): 123-27.

Improved diagnostic accuracy with 16-row Multislice Improved diagnostic accuracy with 16-row Multislice CT Coronary AngiographyCT Coronary Angiography

• N=51N=51

• All had stable angina or atypical chest painAll had stable angina or atypical chest pain

• Beta-blockers used for HR>75Beta-blockers used for HR>75

• 64 significant lesions64 significant lesions

• Sensitivity = 95%Sensitivity = 95%

• Specificity = 98%Specificity = 98%

• PPV = 87%PPV = 87%

• NPV = 99%NPV = 99%

Mollet N, Cademartiri F, Krestin G, et.al. JACC, (45): 128-32.

Atheromatous PlaqueAtheromatous Plaque

CCTA v. IVUSCCTA v. IVUS

• 58 vessels 58 vessels • 78% sensitive for hypoechoic plaque (HU 78% sensitive for hypoechoic plaque (HU

49 +/-22)49 +/-22)• 78% sensitive for hyperechoic plaque (HU 78% sensitive for hyperechoic plaque (HU

91 +/- 22)91 +/- 22)• 95% sensitive for calcified plaque (HU 391 95% sensitive for calcified plaque (HU 391

+/- 156)+/- 156)• Leber et.al., J Am Coll Cardiol, 2004; 43(7): Leber et.al., J Am Coll Cardiol, 2004; 43(7):

1241-7.1241-7.

CCTA v. IVUSCCTA v. IVUS

• 83 coronary segments83 coronary segments

• Any plaque = 78% sens, 87 spec.Any plaque = 78% sens, 87 spec.

• Ca++ plaque = 94% sens, 94% spec.Ca++ plaque = 94% sens, 94% spec.

• NonCa++ plaque = 78% sens, 87% NonCa++ plaque = 78% sens, 87% spec.spec.

• But….But….

CCTA v. IVUSCCTA v. IVUS

• If limited to proximal vessels:If limited to proximal vessels:

• Any plaque = 92% sens, 88% spec.Any plaque = 92% sens, 88% spec.

• Ca++ plaque = 95% sens, 91% spec.Ca++ plaque = 95% sens, 91% spec.

• NonCa++ plaque = 91% sens, 89% NonCa++ plaque = 91% sens, 89% spec.spec.

• Achenbach, et.al., Circulation, 2004; Achenbach, et.al., Circulation, 2004; 109:14-7.109:14-7.

What can the past tell us about What can the past tell us about the future?the future?

• Natural history of CTA abdomen, Natural history of CTA abdomen, neck and intracranial arteries.neck and intracranial arteries.

• Period of time when older and newer Period of time when older and newer technologies will overlap and both be technologies will overlap and both be used to diagnosis until confidence in used to diagnosis until confidence in new technology strengthens.new technology strengthens.

30 year old male with Strong Family History of

CAD

How is it Different from other How is it Different from other heart tests?heart tests?

• Calcium Scoring:Calcium Scoring: only measures quantity of only measures quantity of calcium, not stenosis or soft plaquecalcium, not stenosis or soft plaque

• PET/ Stress Test: PET/ Stress Test: myocardial perfusion only, no myocardial perfusion only, no anatomy. anatomy.

• Echocardiography:Echocardiography: Wall motion and real time Wall motion and real time anatomic evaluation of the four chambersanatomic evaluation of the four chambers

• Cardiac Cath: Cardiac Cath: Lumen only-no wall information. Lumen only-no wall information. Evaluate stenosis. Cannot characterize plaque. Evaluate stenosis. Cannot characterize plaque. Better delineates small vesselsBetter delineates small vessels

Coronary CTA- StrengthsCoronary CTA- Strengths

• Noninvasive.Noninvasive.• Only NONINVASIVE study that Only NONINVASIVE study that

visualizes the vulnerable plaque.visualizes the vulnerable plaque.• Identifies significant disease in Identifies significant disease in

patients with zero or near zero patients with zero or near zero Calcium Scores.Calcium Scores.

• Better sensitivity and specificity than Better sensitivity and specificity than nuclear medicine stress tests, stress nuclear medicine stress tests, stress echo and standard treadmill studies.echo and standard treadmill studies.

Coronary CTA- StrengthsCoronary CTA- Strengths

• Can measure HU of plaques and Can measure HU of plaques and characterize them as fatty, atheroma, characterize them as fatty, atheroma, fibrosis, calcium.fibrosis, calcium.

• Can evaluate status of bypass grafts.Can evaluate status of bypass grafts.

• Can determine stent patency. Can determine stent patency.

• Future- measure the thickness of the Future- measure the thickness of the fibrous cap, functional CT.fibrous cap, functional CT.

• Evaluates portions of mediastinum and Evaluates portions of mediastinum and lungs.lungs.

Coronary CTA- WeaknessesCoronary CTA- Weaknesses

• Cannot accurately measure stenosis with Cannot accurately measure stenosis with heavy, calcified plaque burden.heavy, calcified plaque burden.

• Measured stenosis is different from cardiac Measured stenosis is different from cardiac catheterization which is an intra-arterial catheterization which is an intra-arterial pressure injection with nitroglycerin on pressure injection with nitroglycerin on board.board.

• Occlusions can be missed by brisk Occlusions can be missed by brisk collateral flow.collateral flow.

• Physician time intensive.Physician time intensive.

What do I do with this What do I do with this information?information?

• Reports will be classified in one of Reports will be classified in one of four categories of severity:four categories of severity: NormalNormal Mild Plaque with No stenosis:Mild Plaque with No stenosis: Risk factor Risk factor

modification. Consider statin or ASA therapy.modification. Consider statin or ASA therapy. Moderate Plaque with mild/Mod Moderate Plaque with mild/Mod

stenosis: stenosis: Statin/ASA therapy and myocardial Statin/ASA therapy and myocardial perfusion study.perfusion study.

Severe Plaque and stenosis: Severe Plaque and stenosis: Cardiac CathCardiac Cath

The EndThe End

Why a radiologist?Why a radiologist?

• 10%-35% of all studies have significant other 10%-35% of all studies have significant other chest findings (Nodules, dissection, nodes chest findings (Nodules, dissection, nodes etc)etc)

• Currently, we are scanning the chest Currently, we are scanning the chest completely for a cardiac study (this may completely for a cardiac study (this may change)change)

• RadiationRadiation– Currently, the dose for this study is in the range of Currently, the dose for this study is in the range of

a cardiac catheterizationa cardiac catheterization– EKG dose modulationEKG dose modulation

Pulmonary EmboliPulmonary Emboli

Teaching Point Teaching Point

““Looking at the entire image is Looking at the entire image is critical. Ancillary findings do occur critical. Ancillary findings do occur

on CCTA. on CCTA.

You must know Chest CT before you You must know Chest CT before you can read Coronary CTA.”can read Coronary CTA.”

40%

80%

EKG Dose Modulation

EKG Gated Dose ModulationEKG Gated Dose Modulation

The Vulnerable PlaqueThe Vulnerable Plaque

• The chemical composition of a plaque The chemical composition of a plaque determines it’s vulnerability to rupturedetermines it’s vulnerability to rupture

• Cholesterol is key part of the makeupCholesterol is key part of the makeup

• Plaques are an inflammatory processPlaques are an inflammatory process

• Plaques initially grow extrinsic and bulge Plaques initially grow extrinsic and bulge adventitia, then grow into the lumen adventitia, then grow into the lumen resulting in stenosisresulting in stenosis

65yo, wf, diabetic with 65yo, wf, diabetic with chest pain and SOB.chest pain and SOB.

Mild CAD, and… Mild CAD, and…

Pulmonary EmboliPulmonary Emboli

Coronary CTA- Advantages Coronary CTA- Advantages over Nuclear Stress Testsover Nuclear Stress Tests

• High Negative Predictive Value. High Negative Predictive Value. “Negative is negative.”“Negative is negative.”

• Positive Predictive Value equal or Positive Predictive Value equal or better with CTA. Data will better with CTA. Data will DEFINITELY improve with 16 channel DEFINITELY improve with 16 channel CT.CT.

• Detects subclinical disease.Detects subclinical disease.

Why is this Technology available only Why is this Technology available only now?now?

• Heart and coronary arteries in Heart and coronary arteries in constant motion.constant motion.

• CT scan speed has increased and CT scan speed has increased and EKG dose modulationEKG dose modulation– Decrease radiation during systolic phase Decrease radiation during systolic phase

when imaging of coronary circ is non-when imaging of coronary circ is non-diagnosticdiagnostic

Coronary CTACoronary CTA

Clinical Presentations of CADClinical Presentations of CAD

• Acute Coronary SyndromeAcute Coronary Syndrome•Myocardial InfarctionMyocardial Infarction

•Sudden DeathSudden Death

• Angina PectorisAngina Pectoris•Stable Stable

•UnstableUnstable

HistologyHistology

InjectorsInjectors

• Any power injector will doAny power injector will do

• Dual phase injector preferredDual phase injector preferred

MedradMedrad

Image ComparisonImage Comparison

• Contrast in left heartContrast in left heart

• Saline in right heartSaline in right heart

• RCA clear of artifactRCA clear of artifact

Image ComparisonImage Comparison

• Contrast in Left heartContrast in Left heart

• Contrast in right heartContrast in right heart

• RCA more difficult to RCA more difficult to

VisualizeVisualize

• Leads to tracking Leads to tracking

problemsproblems

ContrastContrast

• Density is NOT the dominant issue!Density is NOT the dominant issue!

• HR is always the dominant issueHR is always the dominant issueDecrease in iodine load results in decrease Decrease in iodine load results in decrease

symptomssymptomsDecrease symptoms results in decrease in HR Decrease symptoms results in decrease in HR

variabilityvariabilityDecrease recon time and better image qualityDecrease recon time and better image quality

Visipaque 320Visipaque 320 on all Coronary CTA’s on all Coronary CTA’s

LightSpeed Pro 16LightSpeed Pro 16

• Improve small vessel visualizationImprove small vessel visualization

• Increase gantry speed (.4sec c/w .5sec)Increase gantry speed (.4sec c/w .5sec)

• EKG Dose modulation. Decrease radiation EKG Dose modulation. Decrease radiation exposureexposure

• Increased mA: decreased artifacts related Increased mA: decreased artifacts related to surgical clips and calcification.to surgical clips and calcification.

– Lightspeed 16 : 400-440mALightspeed 16 : 400-440mA– Lightspeed 16 Pro : 400-670mA (800mA)Lightspeed 16 Pro : 400-670mA (800mA)

EKG Gated Dose ModulationEKG Gated Dose Modulation

• Decreases radiation exposure during the Decreases radiation exposure during the time in the cardiac cycle where you are time in the cardiac cycle where you are unlikely to reconstruct the coronary unlikely to reconstruct the coronary arteries.arteries.

• Never reconstruct 0-30% and 81-100% of Never reconstruct 0-30% and 81-100% of the R-R intervalthe R-R interval

• Peak mA between 40-80%Peak mA between 40-80%

• Min mA set at 20-40% of max mAMin mA set at 20-40% of max mA

EKG Gated Dose ModulationEKG Gated Dose Modulation

• Always reconstruct 70-80% of the R-R Always reconstruct 70-80% of the R-R interval by 5’sinterval by 5’s

• With variable HR’s or motion reconstruct With variable HR’s or motion reconstruct 40-80% by 5’s40-80% by 5’s

Typical Injection ProtocolTypical Injection Protocol

• Manual Timing Bolus= 20cc contrast+20cc SalineManual Timing Bolus= 20cc contrast+20cc Saline

• Coronary CTA= 80-100 cc contrast + 50cc SalineCoronary CTA= 80-100 cc contrast + 50cc Saline

Scan ParametersScan Parameters

• 16 X 0.625mm, <15 slab, 15-20sec breath hold, 16 X 0.625mm, <15 slab, 15-20sec breath hold, 120 kvp, > 400mA120 kvp, > 400mA

• Large Patients = 16 X 0.625mm, <15 slab, 15-Large Patients = 16 X 0.625mm, <15 slab, 15-20sec breath hold, 120kvp, >400 mA. 20sec breath hold, 120kvp, >400 mA. Retrospectively thicken to 1.25mm if needed.Retrospectively thicken to 1.25mm if needed.

• COPD = 16 X 1.25mm, <15 slab, 8-10 sec breath COPD = 16 X 1.25mm, <15 slab, 8-10 sec breath hold, 120 kvp, >400mAhold, 120 kvp, >400mA

PearlsPearls

• Watch HR during all breath holds to adjust scan Watch HR during all breath holds to adjust scan parameters as needed.parameters as needed.

•HR normally decreases 5-10 bpm during HR normally decreases 5-10 bpm during breath holdbreath hold

•COPD patients get hypoxic and HR increases COPD patients get hypoxic and HR increases with breath holdwith breath hold switch to COPD protocol switch to COPD protocol

• On large patients, opt for increasing slice On large patients, opt for increasing slice thickness to 1.25mm rather than decreasing mA.thickness to 1.25mm rather than decreasing mA.

These studies were NOT These studies were NOT done on a high mA, EKG done on a high mA, EKG dose modulated system.dose modulated system.

Teaching PointTeaching Point

““CCTA is outstanding for CCTA is outstanding for determining who does NOT determining who does NOT have CAD. These patients have CAD. These patients

can be safely evaluated at the can be safely evaluated at the primary care level. In some primary care level. In some

circumstances CCTA over calls circumstances CCTA over calls disease but it still disease but it still

outperforms stress tests.” outperforms stress tests.”

SummarySummary

• Coronary CTA is not just a modified CT Coronary CTA is not just a modified CT Pulmonary angiogram study. Pulmonary angiogram study.

• Requires more active technologist and Requires more active technologist and radiologist involvement and modification.radiologist involvement and modification.

• Tremendous potential to detect significant Tremendous potential to detect significant CAD earlier.CAD earlier.

• The technology will only continue to The technology will only continue to improve.improve.