ComputedTomography
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Motion-compensatedreconstruction for coronary imaging
Precise Cardiac

Overview
Philips Precise Cardiac is a novel approach with the ability to compensate
for cardiac motion in CT imaging, improving visualization of the coronary arteries.
This can help salvage some of the coronary segments deemed non-diagnostic
using standard cardiac reconstructions, increasing diagnostic confidence
in coronary CTA exams.

Background
Coronary computed tomography angiography (coronary CTA)
has become the preferred noninvasive modality for the detection
and rule-out of coronary artery disease (CAD), by providing
an assessment of the coronary anatomy and visualization ofatherosclerotic plaque to aid in detection of lesions that may
limit blood flow to the myocardium. However, there are multiple
challenges in imaging coronary arteries with the use of CT.
These arteries are small with a caliber approaching 1 mm or lessat their most distal ends, and they exhibit complex 3D motion
during the cardiac cycle, which contributes to motion artifacts
during cardiac imaging.1,2 In addition, the limited temporal
resolution of coronary CTA is insufficient to address these motionartifacts, resulting in non-evaluable coronary segments, which
impacts diagnostic performance.

Precise Cardiac compensates for cardiac motion in CT studies.

While motion artifacts are more pronounced and common at higherof the severe gravitational forces imposed upon the system.

and variable heart rate (HR), they could also occur at lower HROver the years, Philips has implemented helical multicycle cardiac

as well. A common clinical practice to counter this is to administerreconstructions to improve image quality.1-3 Because it is adaptive

medication to lower and stabilize the HR. Additionally, onein nature, this approach combines data from multiple cardiac cycles

technical approach is to increase the rotation speed of the gantry

without any user input to optimize temporal resolution and thus

to improve the native temporal resolution of the system. However,improve the coronary image quality and diagnostic performance

this approach is not practical beyond a certain limit becauseof coronary CTA.

Philips CT Smart Workflow
Precise Cardiac is one of the many AI-enabled* tools of CT Smart Workflow,which includes AI that is deeply embedded into tools clinicians use every day
to be able to apply their expertise to the patient, not the process.

Precise Cardiac
As a technology innovation leader in cardiac imaging, Philips

This sophisticated approach avoids the need for any manual

has recently introduced a novel reconstruction approachintervention by employing efficient filtering techniques in acomplementing adaptive reconstruction techniques. The motion-

pre-defined region around a targeted cardiac phase to identify

compensation reconstruction of Precise Cardiac offers a novel,

the relevant objects and dynamically tracking their motion

zero-click technique generating a single series of motion-correctedbehavior in the localized portion of the cardiac cycle. By taking

images applicable to both modes of coronary CTA scans

into account the displacement of structures and performing(retrospectively gated helical and prospectively gated axial

the relevant corrections as part of the back-projection process,[Step & Shoot Cardiac]).4-7

motion-corrected images are generated.

* According to the definition of AI from the EU High-Level Expert Group.

Precise Cardiac processing steps
Standard cardiac processing pipelineScan

Sinogram datawith EKG strip

Target phase

Back projection

Motion-corrected image

Precise Cardiac
processing pipeline

Phase neighbor range

Target phase

Elastic registration, motion
estimation and correction MVF

Motion vector field (MVF) describes the motion of the heart around a target phase

The processing pipeline shows how Precise Cardiac corrects for cardiac motion to improve visualization in cardiac scans.
2A recent pilot study of 28 patients demonstrated theeffectiveness of this approach in improving the quality ofvisualization of all coronary arteries, while maintaining thesignal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR).
The mean HR of the patients during the scan was 86 ±11 bpm(range: 68–114 bpm). The resulting visualization scores werehigher with the use of motion-compensation reconstruction
for all coronary artery segments compared to the routine
gated reconstructions.8

Performance
The use of Precise Cardiac demonstrates significant improvements in image
quality of the entire right coronary artery (RCA), compared with standard cardiac
reconstructions. Correcting for motion in the coronary arteries potentially saves
a patient a repeat scan.

Philips Incisive CT

Original

Precise Cardiac

Philips Spectral CT 7500

Original

Precise Cardiac

Scan parameters – 120 kVp, 697 mAs, CTDIvol 56.5 mGy,
DLP 678 mGy* cm, effective dose 9.5 mSv (k=0.014)

Sample images acquired in a clinical study of the Spectral CT
7500 system at Tel Aviv Sourasky Medical Center (Ichilov), Israel.

Middle-aged patient admitted with chest pain and shortnessof breath, average HR: 61 bpm.

Precise Cardiac eliminated motion observed in RCA, HR: 77 bpm.

3Conclusion
Philips Precise Cardiac is a novel technological innovation that features the ability to compensate for cardiac
motion to improve visualization of the coronary arteries during CT imaging. Precise Cardiac can help salvage
some coronary segments previously deemed nondiagnostic using standard cardiac reconstructions, thusincreasing the diagnostic confidence in coronary CTA exams and potentially opening up newer applications.

References
1. Vembar M, et al. A dynamic approach to identifying desired physiological phases for cardiac imaging using multislice spiral CT. Med Phys.
2003;0(7):1683–93. DOI: 10.1118/1.1582812.
2. Vembar M, et al. Cardiac imaging using multislice computed tomography scanners: technical considerations. Coron Artery Dis. 2006;17(2):115–23.
DOI: 10.1097/00019501-200603000-00004.
3. Grass M, et al. Helical cardiac cone beam reconstruction using retrospective ECG gating. Phys Med Biol. 2003;48(18):3069–84.
DOI: 10.1088/0031-9155/48/18/308.
4. Koken P, et al. Aperture weighted cardiac reconstruction for cone-beam CT. Phys Med Biol. 2006;51(14):3433–48. DOI: 10.1088/0031-9155/51/14/011.
5. Grass M, et al. Fully automatic cardiac CT motion compensation using vessel enhancement. Presented at Society of Cardiovascular Computed
Tomography annual meeting. 2016. Orlando, FL.
6. Grass M, et al. Fully automatic cardiac CT motion compensation using vessel enhancement. Presented at Radiological Society of North America
annual meeting. 2016. Chicago, IL.
7. Van Stendaal U, et al. A motion-compensated scheme for helical cone-beam reconstruction in cardiac CT angiography. Med Phys.
2008;35(7):3239–51. DOI: 10.1118/1.2938733.
8. Balaney B, et al. Improved visualization of the coronary arteries using motion correction during vasodilator stress CT myocardial perfusion imaging.
Eur J Radiol. 2019;114:1–5. DOI: 10.1016/j.ejrad.2019.02.010.

Results from case studies are not predictive of results in other cases. Results in other cases may vary.

© 2021 Koninklijke Philips N.V. All rights are reserved.
Philips reserves the right to make changes in specifications
and/or to discontinue any product at any time without noticeor obligation and will not be liable for any consequences
resulting from the use of this publication.

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4522 991 73391 * NOV 2021