Study / Scientific Publication

Coronary artery disease (CAD)

Coronary artery disease

Coronary artery disease (CAD) is one of the major causes of death in industrialized countries, and one of the leading causes of years of life lost due to premature mortality.

Dynamic CT perfusion is a CT technique that offers the possibility to quantify myocardial blood flow (MBF) and detect perfusion defects.

This experimental study showed that the absolute MBF are substantially underestimated as a result of low temporal sampling rates in conventional scan modes. 

Keywords: Perfusion imaging, Computed tomography, Cardiac imaging techniques, X-Ray Imaging, Echocardiography, Nuclear Cardiology, Computed Tomography and Magnetic Resonance Imaging

Coronary artery disease (CAD) - Study

Study:

The purpose of this study was to evaluate the effect of temporal sampling rate in dynamic CT myocardial perfusion imaging (CTMPI) on myocardial blood flow (MBF). 

Recent technical developments in the field of computed tomography (CT) make this imaging modality a suitable candidate for cardiac perfusion measurements. 

Dynamic CTMPI advantages

Dynamic CTMPI has several advantages over competing imaging modalities, namely cost, availability, spatial resolution and the linear relation between Hounsfield unit (HU) enhancement and contrast in the myocardium, facilitating quantification.

Using a combination of CT angiography (CTA) and CTMPI the morphological and functional aspects of CAD can be evaluated with a single non-invasive imaging modality.

Abstract

The purpose of this study was to evaluate the effect of temporal sampling rate in dynamic CT myocardial perfusion imaging (CTMPI) on myocardial blood flow (MBF). 

Dynamic perfusion CT underestimates myocardial blood flow compared to PET and SPECT values.

For accurate quantitative analysis of myocardial perfusion with dynamic perfusion CT a stable calibrated HU measurement of MBF is essential. 

  • Three porcine hearts were perfused using an ex-vivo Langendorff (PhysioHeart™) model.
  • Hemodynamic parameters were monitored.
  • Dynamic CTMPI was performed using third generation dual source CT at 70 kVp and 230–350 mAs/rot in electrocardiography(ECG)-triggered shuttle-mode (sampling rate, 1 acquisition every 2–3 s; z-range, 10.2 cm), ECG-triggered non-shuttle mode (fixed table position) with stationary tube rotation (1 acquisition every 0.5–1 s, 5.8 cm), and non-ECG-triggered continuous mode (1 acquisition every 0.06 s, 5.8 cm). 
  • Stenosis was created in the circumflex artery, inducing different fractional flow reserve values. 
  • Volume perfusion CT Myocardium software was used to analyze ECG-triggered scans.
  • For the non-ECG triggered scans MASS research version was used combined with an in-house Matlab script.
  • MBF (mL/g/min) was calculated for non-ischemic segments. True MBF was calculated using input flow and heart weight. 

In this proof of principle study we evaluate the effect of increased temporal sampling rates on quantification of MBF in dynamic CTMPI with 3rd generation dual-source CT in an ex-vivo porcine heart model:

  • Shuttle | Non-shuttle | Continuous
    Shuttle | Non-shuttle | Continuous
    Shuttle | Non-shuttle | Continuous
  • Arterial Input Function
    Arterial Input Function
    Arterial Input Function
  • LifeTec Group PhysioHeart Setup
    LifeTec Group PhysioHeart Setup
    LifeTec Group PhysioHeart Setup

Significant differences in MBF between shuttle, non-shuttle and continuous mode were found, with median MBF of 0.87 [interquartile range 0.72–1.00], 1.20 (1.07–1.30) and 1.65 (1.40–1.88), respectively.

The median MBF in shuttle mode was 56% lower than the true MBF.

In non-shuttle and continuous mode, the underestimation was 41% and 18%.

Limited temporal sampling rate in standard dynamic CTMPI techniques contributes to substantial underestimation of true MBF.

Perspectives

Competency in medical knowledge

Dynamic CT perfusion is a CT technique that offers the possibility to quantify myocardial blood flow and detect perfusion defects. This experimental study showed that the absolute MBF are substantially underestimated as a result of low temporal sampling rates in conventional scan modes. An increase in temporal sampling rates not only increased the absolute MBF values, but also increased the accuracy of the measurement compared to the true myocardial blood flow.

 

Translational outlook

Future studies are needed to establish the optimal trade-off between increased radiation dose and more accurate myocardial blood flow estimates. As a consequence of the effect of temporal sampling rates, threshold to determine perfusion defects, should be corrected for the specific temporal sampling rates used.

Authors / Affiliates:

Matthijs Oudkerk | Marly van Assen | Gert Jan Pelgrim | Emmy Slager | Sjoerd van Tuijl | Joseph Schoepf | Rozemarijn Vliegenthart | 

  • Department of Radiology, Center for Medical Imaging-North East Netherlands, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands 
  • LifeTec Group BV, Eindhoven, The Netherlands 
  • Medical University South Carolina, Charleston, SC, USA
  • Center for Medical Imaging-North East Netherlands, University of Groningen, University Medical Center Groningen, EB44, Hanzeplein 1, 9713 GZ Groningen, The Netherlands 

 

Journal Title

The International Journal of Cardiovascular Imaging | Volume 1 / 1985 - Volume 34 / 2018 | Print ISSN 1569-5794 | Online ISSN 1573-0743 | Publisher: Springer Netherlands

Please do not hesitate to contact Sjoerd van Tuijl if you require any further information:

Senior Research Engineer
Sjoerd van Tuijl
Call at +31 40 2 98 93 93 or e-mail us

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