brink ccta protocols contrast media optimization...coronary ct angiography: protocols contrast media...

Coronary CT Angiography: Protocols Contrast Media Optimization

James A. Brink, M.D.

Yale University

School of Medicine

Cardiac CT Angiography

• Intravenous Contrast Material• Flow Rate• Concentration• Type• Duration (Volume)• Scan Delay

Iodine Concentration in Blood/Tissue

Concentration (I mg/cc)

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120 Kvp

137 Kvp

Tissue Concentration (I mg/ml)

25 HU per mg I / ml

Peak Enhancement vs. Flow Rate

ComputerSimulation

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Time after the start of injection (sec)

Recirculation

Increase in bloodflow caused bythe injection

Courtesy of Ty Bae

InjectionDuration

Injection Duration

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Porcine Model

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30-sec injection20-sec injection12-sec injection8-sec injection5-sec injection3-sec injection1-sec injection

Computer Simulation

Bae KT. Radiology 2003;227:809-816

Duration(Volume)Duration(Volume)

IV Contrast for CTA

Injection Duration = Scan Duration

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30-sec20-sec12-sec8-sec5-sec3-sec1-sec

30 sec4DCT

8 sec16DCT

InjectionDuration

30 sec4DCT8 sec

16DCT

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8 sec16DCT

8 sec16DCT

InjectionDuration

8 sec16DCT

IV Contrast for CTA

Injection Duration = Scan DurationSDCT and 4DCT:

Injection Duration = Scan Duration + 1016DCT and 64DCT:

Saline Flush

• Facilitated with double-barrel injector

• Eliminates messy loading of saline on top of contrast in single-barrel systems

Saline Flush

• Eliminates excess contrast in tubing

• Flushes contrast from peripheral veins into central veins

• Permits reduction in contrast volume by about 20 to 40%

• Reduces beam hardening artifact in RCA

64DCT – Uni Flow• 2 Injection Phases:

• Contrast

• Saline

• Less contrast material, but no visualization of right heart w/ dilute contrast

• Better definition / segmentation of left heart and coronary arteries

64DCT – Uni Flow

64DCT – Uni Flow (Yale)

• 2 Injection Phases: (Iodixanol 320, 5ml/s)

• Contrast 70 ml (14s)

• Saline 30 ml (6s)

• Scan duration = 3-5 sec • Injection duration = 14 sec • Injection duration = Scan duration + 10 sec

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InjectionDuration

14-sec

3-5 sec64DCT

3-5 sec64DCT

64DCT -- Dual Flow

• 3 Injection Phases:

• Contrast

• Contrast + Saline

• Saline

• Permits visualization of right heart and interventricular septum w/ dilute contrast

64DCTDual Flow

64DCT -- Dual Flow

RCA LAD LCX

64DCT -- Dual Flow (Yale)

• 3 Injection Phases: (Iodixanol 320, 5ml/s)

• Contrast 60 ml (12s)

• Contrast(60%) + Saline(40%) 50 ml (10s)

• Saline 40 ml (8s)

• Scan duration = 3-5 sec • ‘Effective’ Injection duration = 18-22 sec

‘Effective’ ID = SD + 15 sec

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‘Effective’InjectionDuration

3-5 sec64DCT

3-5 sec64DCT

64DCT – Dual Flow

• Right heart visualization

• Right heart mass

• Valve disease

• Prolonged injection duration:• Triple Rule-Out• Complete thorax (CABG)

64DCT – Dual Flow – Triple R/O

Prospective Gating

(100 kV; 5-7 mSv)

Scan DelayScan Delay

Scan Delay for Cardiac CTA

• Scan Delay

• May be fixed for patients presumed to have normal cardiac output - risky

• Pitfall

• Abnormal cardiac output --> marked delay in vascular enhancement

• test bolus or bolus tracking

Cardiac Output --> Aortic Enhancement

Time (min)

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c.o. = 25%

c.o. = 50%

c.o. = 100%

c.o. = 200%

Computer Simulation, 5ml/sec. Bae, Heiken, Brink. Radiology Radiology 1998; 207:657-662

Test Bolus

• Measure circulation time• 20 ml @ 5 ml/sec (4 sec inj.)• Scan at carina (Asc. Aorta & PAs):

• 10 - 30 sec q 1-2 sec

• Plot enhancement curve and find peak• If no peak, change arm position, repeat

Test Bolus

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14 16 18 20 22 24 26 28 30 32 34

Time (sec)

4 sec

4DCT 64DCT

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3-5 sec64DCT

3-5 sec64DCT

Peak + 4-8 sec

Timing for Dual Flow 64DCT CCTA

Bolus Tracking

• ROI in aorta (usually descending aorta)

• Low-dose monitoring scans q 1-2 sec

• Trigger when enhancement > 100 HU• Absolute value of 150 HU

• Add delay to initiate scanner, breath-hold patient, and allow adequate enhancement

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3-5 sec64DCT

3-5 sec64DCT

ContrastArrival

‘Eff’ Inj Duration+ -Scan

Duration

3-5 sec64DCT

Timing for Dual Flow 64DCT CCTA

Triple Rule-Out: Test Bolus

Scan delay is mid-point between time to peak in PA and Aorta

10 sec64DCT

10 sec64DCT16 36

Pulmonary Artery

25 45

Aorta

Triple Rule-Out: Dual Flow 64DCT ‘Effective’InjectionDuration: 20 sec

Cardiac CTA: Protocol Development

• Technique

• Flow Rate

• Concentration

• Volume

• Scan Delay

• 64DCT Uni Flow

• 5 ml/sec

• 320-370 mgI/ml

• 70(100%), 30(NS)

• Test Bolus + 4-8 sec*

• 64DCT Uni Flow

• 5 ml/sec

• 320-370 mgI/ml

• 70(100%), 30(NS)


* Bolus Tracking: Contrast Arrival + Injection Duration - Scan Duration

Cardiac CTA: Protocol Development

• Technique

• Flow Rate

• Concentration

• Volume

• Scan Delay

• 64DCT Dual Flow

• 5 ml/sec

• 320-370 mgI/ml

• 60(100), 50(60/40), 40(NS)


• 64DCT Dual Flow

• 5 ml/sec

• 320-370 mgI/ml

• 60(100), 50(60/40), 40(NS)


* Bolus Tracking: Contrast Arrival + Injection Duration - Scan Duration

brink ccta protocols contrast media optimization...coronary ct angiography: protocols contrast media...

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