Philips_Cardiac_CCTA_Protocol

HeartFlow, Inc. | Acquisition and Reconstruction Techniques for Coronary CT Angiography: Philips Healthcare Scanner Platforms | 15991244 V4

1. Overview
2. Introduction

Importance of Heart Rate Control
Importance of Nitrates
Selection of Tube Current and Potential

3. Recommended Protocol: PHILIPS BRILLIANCE iCT and IQon SPECTRAL CT

Surview
CTA Acquisition
CTA Post-processing (Reconstructions)
Contrast Protocol

4. Recommended Protocol: PHILIPS BRILLIANCE iCT SP

Surview
CTA Acquisition
CTA Post-processing (Reconstructions)
Contrast Protocol

5. Bibliography

Table of Contents

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HeartFlow, Inc. | Acquisition and Reconstruction Techniques for Coronary CT Angiography: Philips Healthcare Scanner Platforms | 15991244 V4

1. Overview

Coronary computed tomography angiography (CCTA) is a non-invasive diagnostic for detecting coronary
artery disease (CAD). CCTA is increasingly utilized in clinical practice for evaluating coronary anatomy for
obstructive disease and plaque.

It is, however, imperative that artifact free CCTA image data is obtained in order for it to be successfully
analysed for anatomic assessment and/or to act as adequate input for adjunct analyses such as physiologic
simulations. Data acquisition strategies and scanning protocols may vary depending on scanner manufacturer,
system, and institutional preferences. This document provides references for reliable image acquisition
for CCTA.

HeartFlow, Inc. | Acquisition and Reconstruction Techniques for Coronary CT Angiography: Philips Healthcare Scanner Platforms | 15991244 V4

2. Introduction

Image acquisition in computed tomography is governed ultimately by the principle of As Low As Reasonably
Achievable (ALARA). In the first 10 years of CCTA, the focus was almost exclusively on the detection of
anatomical stenosis in low to intermediate risk patients. With the evolution of technology, the clinical utility
of CCTA has extended beyond stenosis assessment to atherosclerosis characterization, the evaluation of
structural heart disease, and the functional and physiological assessment of coronary stenoses. Recently
the SCCT acquisition guidelines were updated and provide an excellent reference for Cardiac CT imaging
specialists to help optimize their scan protocols. That being said, given the growing information that is
provided from cardiac CT, the imaging requirements have evolved and require tailoring to meet the clinical
indication. The purpose of this white paper is to highlight the parameters and image acquisition protocols that
are important to help optimize image quality, provide accurate representation of anatomy and thus enable
quantitative CT.

Importance of Heart Rate Control

With the advancements in scanner technology, the necessary requirement for heart rate reduction has
decreased over time. The demands for a low and steady heart rate to ensure diagnostic image quality may not
be what they once were but best practice remains to optimize image quality through heart rate control. SCCT
guidelines recommend performing CCTA with heart rates below 60 bpm.

In addition, CCTA no longer simply provides stenosis evaluation but needs to enable the interpreting physician
to identify and characterize plaque and, following the identification of a stenosis, to perform functional or
physiologic evaluation. As a result, while latest generation CT scanners may enable diagnostic image quality
at higher heart rates, there remains meaningful image quality benefits from heart rate reduction. In addition,
lower heart rates allow the use of lower dose scan acquisitions that are not possible at higher heart rates. Heart
rate control strategies are well established and the appropriate strategy is dependent on a number of variables
including available medications, setting of practice and site preference. For recommendations please refer to
the recently updated SCCT acquisition guidelines.

Importance of Nitrates

Nitrates as smooth muscle dilators have direct effect on coronary vasodilation and result in tangible
enlargement of coronary size. As such, similar to invasive coronary catheterization, nitroglycerine (glyceryl
trinitrate) should be administered prior to CCTA to optimize image quality and enable the most accurate
stenosis evaluation. A commonly used regimen is 400-800 µg of sublingual nitroglycerin administered as either
sublingual tablets or a metered lingual spray (commonly 1-2 tablets or 1-2 sprays) prior to the CCTA. While
the evidence is modest and there is no randomized data, both a higher dose and administration via spray are
becoming increasingly preferred in clinical practice and have been shown to help optimize coronary evaluation.

HeartFlow, Inc. | Acquisition and Reconstruction Techniques for Coronary CT Angiography: Philips Healthcare Scanner Platforms | 15991244 V4

Selection of Tube Current and Potential

The scan parameters used for any cardiac CT should be tailored to the individual patient but also the intended
application. The image quality issues with the greatest impact on the interpretability of CT are misalignment
and image noise. As such, care must be given to ensure that image noise properties are appropriate and
adequate for accurate lumen segmentation. To do so, tube current and potential should be selected carefully,
guided by chest wall circumference, the iodine concentration of the intravenous contrast medium, and whether
iterative reconstruction is available or not.

Iterative reconstruction (IR) has the ability to reduce image noise in CT without compromising the diagnostic
quality of the CT image dataset, which permits a significant reduction in effective radiation dose. In current
clinical practice, IR has enabled a significant reduction in radiation dose by allowing for a reduction in tube
current and is now increasingly available across all cardiac capable CT scanners. IR commonly takes the form
of a blended reconstruction of IR and filtered back projection (FBP). While a very helpful tool, care should
be given when using a very high percentage of IR for quantitative CT analysis due to the potential impact on
vessel segmentation.

HeartFlow, Inc. | Acquisition and Reconstruction Techniques for Coronary CT Angiography: Philips Healthcare Scanner Platforms | 15991244 V4

3. Recommended Protocol:

PHILIPS BRILLIANCE iCT and IQon

SPECTRAL CT

1. Surview

General

Data Acquisition

Comments

Lateral and AP surview covering the

heart and coronaries

• AP Surview: 120kVp/50mA
• Lat Surview: 120kVp/100mA
• Surview Angle: Dual
• Surview Length (mm): 300
• Surview FOV: 500
• Surview Auto Voice: S Ins
• Surview Breathing Lights: Yes

Position the patient for AP surview to

acquire AP and lateral surview.

Offset the patient to the right so the

heart is at the center of the scan field.

Place the patient's arms above their

head with the ECG leads outside the

scan range.
Have the patient practice breath-

holding before starting the

examination. This should be a single

"breathe in and hold" command.

2. CTA Acquisition

General

Data Acquisition

Data Reconstruction

Acquiring CT coronary Angiogram

Helical CCTA Acquisition
• kV: 120 or 100 when appropriate
• mAs: 800 (standard patients),

1000 (large patients)

• Scan Type: Cardiac
• DoseRight: Off
• Cardiac DoseRight: On
• Collimation: Auto
• Pitch: 0.16
• Rotation Time: 0.27
• No of cycles/scan: N/A
• Scan time 5.30 seconds
• Resolution: STD
• Auto Voice: s.insp.

Stepandshoot,breath (longer

instruction with longer delay

at end)

• Breathing Lights: Yes
• Auto Pitch & RT based on HR: No
• ECG Gating Phase: 78%
• Handle irregularities On-line: Yes

Coronary CTA (Acquisition)
• Field of View limited to the heart

(220 mm)

• Slice thickness 0.8mm
• Increment 0.4mm
• Acquisition Length (mm) 140.4
• Result Scan Length (mm): 140.4

HeartFlow, Inc. | Acquisition and Reconstruction Techniques for Coronary CT Angiography: Philips Healthcare Scanner Platforms | 15991244 V4

2. CTA Acquisition (contd.)

General

Data Acquisition

Data Reconstruction

Step & Shoot (Acquisition)
• kV: 120
• mAs: 155 to 200 if phase

tolerance = 0
phase tolerance = 5, system will
recommend more mAs

• Scan Type: Cardiac
• Collimation: Auto
• DoseRight: Off
• Cardiac DoseRight: On
• Pitch: N/A
• No of cycles/scan: IQon 4, iCT 2
• Scan time: 4-9 seconds
• Rotation Time: 0.27
• Resolution: STD
• Auto Voice: s.insp.

Stepandshoot,breath (longer

instruction with longer delay

at end)

• Breathing Lights: Yes
• Auto Pitch & RT based on HR: N/A
• ECG Gating Phase: 78%
• Handle irregularities On-line: Yes
• ECG Gating Phase Tolerance: 5%

Step & Shoot (Acquisition)
• Field of View limited to the heart

(220 mm)

• Slice thickness 0.8mm
• Increment 0.4mm
• Acquisition Length (mm) 144.5
• Result Scan Length (mm): 140.8

HeartFlow, Inc. | Acquisition and Reconstruction Techniques for Coronary CT Angiography: Philips Healthcare Scanner Platforms | 15991244 V4

3. CTA Post-processing (Reconstructions)

General

Data Acquisition

Data Reconstruction

Coronary CTA (Acquisition)
• Reconstructions: Standard
• iMR Level: None
• iDose Level: 3 to 5
• Filter: XCB and XCC
• Single Cycle Reconstruction: No
• ECG Gating Recon Phase: 78%
• Edge Correction: N/A

Step & Shoot (Acquisition)
• Reconstructions: Standard
• iMR Level: None
• iDose Level: 3 to 5
• Filter: XCB and XCC
• Single Cycle Reconstruction: No
• ECG Gating Recon Phase: 78%
• Edge Correction: No

4. Contrast Protocol

General

Parameter

Comments

The injection rate should be

increased for shorter scan times and

larger patients!
CTA requires contrast medium with

an iodine concentration of at least

350 mgI/mL.
Place a 20- or 18-gauge IV cannula in

the RIGHT arm.

Coronary CTA & Large (Acquisition)
• Bolus Tracking: Yes
• Trigger: 100 HU over blood

base line

• Post Threshold Delay: 5 Seconds

Step & Shoot (Acquisition)
• Bolus Tracking: Yes
• Trigger: 100 HU over blood

base line

• Post Threshold Delay: 7 Seconds

HeartFlow, Inc. | Acquisition and Reconstruction Techniques for Coronary CT Angiography: Philips Healthcare Scanner Platforms | 15991244 V4

4. Recommended Protocol:

PHILIPS BRILLIANCE iCT SP

1. Surview

General

Data Acquisition

Comments

Lateral and AP surview covering the

heart and coronaries

• AP Surview: 120kVp/50mA
• Lat Surview: 120kVp/100mA
• Surview Angle: Dual
• Surview Length (mm): 300
• Surview FOV: 500
• Surview Auto Voice: S Ins
• Surview Breathing Lights: Yes

Position the patient for AP surview to

acquire AP and lateral surview.

Offset the patient to the right so the

heart is at the center of the scan field.

Place the patient's arms above their

head with the ECG leads outside the

scan range.
Have the patient practice breath-

holding before starting the

examination. This should be a single

"breathe in and hold" command.

2. CTA Acquisition

General

Data Acquisition

Data Reconstruction

Acquiring CT coronary Angiogram

Helical CCTA Acquisition
• kV: 120
• mAs: 800 (standard patients),

1000 (large patients)

• Scan Type: Cardiac
• DoseRight: Off
• Cardiac DoseRight: On
• Collimation: Auto
• Pitch: 0.16
• Rotation Time: 0.27
• No of cycles/scan: N/A
• Scan time 8.20 seconds
• Resolution: STD
• Auto Voice: s.insp.

Stepandshoot,breath (longer

instruction with longer delay

at end)

• Breathing Lights: Yes
• Auto Pitch & RT based on HR: No
• ECG Gating Phase: 78%
• Handle irregularities On-line: Yes

Helical CCTA Acquisition
• Field of View limited to the heart

(220 mm)

• Slice thickness 0.8mm
• Increment 0.4mm
• Acquisition Length (mm) 140.4
• Result Scan Length (mm): 140.4

HeartFlow, Inc. | Acquisition and Reconstruction Techniques for Coronary CT Angiography: Philips Healthcare Scanner Platforms | 15991244 V4

2. CTA Acquisition (contd.)

General

Data Acquisition

Data Reconstruction

Step & Shoot CCTA Acquisition
• kV: 120
• mAs: 155
• Scan Type: Cardiac
• Collimation: Auto
• DoseRight: Off
• Cardiac DoseRight: On
• Pitch: N/A
• No of cycles/scan: 4
• Scan time: 9.17 seconds
• Rotation Time: 0.27
• Resolution: STD
• Auto Voice: s.insp.

Stepandshoot,breath (longer

instruction with longer delay

at end)

• Breathing Lights: Yes
• Auto Pitch & RT based on HR: N/A
• ECG Gating Phase: 78%

irregularities On-line: Yes

• ECG Gating Phase Tolerance: 5%

Step & Shoot CCTA Acquisition
• Field of View limited to the heart

(220 mm)

• Slice thickness 0.8mm
• Increment 0.4mm
• Acquisition Length (mm) 144.5
• Result Scan Length (mm): 134.8

HeartFlow, Inc. | Acquisition and Reconstruction Techniques for Coronary CT Angiography: Philips Healthcare Scanner Platforms | 15991244 V4

3. CTA Post-processing (Reconstructions)

General

Data Acquisition

Data Reconstruction

Acquiring CT coronary Angiogram

4. Contrast Protocol

General

Parameter

Comments

The injection rate should be

increased for shorter scan times and

larger patients!
CTA requires contrast medium with

an iodine concentration of at least

350 mgI/mL.
Place a 20- or 18-gauge IV cannula in

the RIGHT arm.

Coronary CTA & Large (Acquisition)
• Bolus Tracking: Yes
• Trigger: 100 HU over blood

base line

• Post Threshold Delay: 5 Seconds

Step & Shoot (Acquisition)
• Bolus Tracking: Yes
• Trigger: 100 HU over blood

base line

• Post Threshold Delay: 7 Seconds

HeartFlow, Inc. | Acquisition and Reconstruction Techniques for Coronary CT Angiography: Philips Healthcare Scanner Platforms | 15991244 V4

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HeartFlow, Inc. | Acquisition and Reconstruction Techniques for Coronary CT Angiography: Philips Healthcare Scanner Platforms | 15991244 V4

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This paper is presented as a service to medical personnel by HeartFlow and Philips. The information in this white paper has been compiled
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WARNING: Any references to x-ray exposure, intravenous contrast dosage, and other medication are intended as reference guidelines only.
The guidelines in this document do not substitute for the judgment of a trained healthcare provider. Each scan requires medical judgment by
the healthcare provider about exposing the patient to ionizing radiation. Use the As Low As Reasonably Achievable (ALARA) radiation dose
principle to balance factors such as the patient’s condition, size and age; region to be imaged; and diagnostic task.