Comparing dynamic contrast enhanced CT with Rb-82 PET for myocardial perfusion assessment in patients with suspicion for chronic coronary syndrome: The DYNAMORE study

Ischemic heart disease is the world*s leading cause of mortality1. For patients
with suspected stable coronary artery disease (CAD) it is recommended to test
for ischemia instead of directly performing invasive coronary angiography2-4.
Coronary computed tomography (CT) angiography can be used to visualize stenosis
in the coronary anatomy and has an excellent negative predictive value for
ruling out CAD5, but is unable to assess the functional significance of
stenosis. Using Rb-82 myocardial perfusion imaging (MPI) with positron emitting
tomography (PET), the functional significance of a stenosis can be assessed
with high sensitivity and specificity. For a full analysis of CAD, anatomical
and functional imaging can be combined. However, the drawbacks of Rb-82 PET are
the availability of PET scanners as well as Rb-82 generators and the associated
high costs.6
Dynamic contrast enhanced CT (DCE-CT) has become possible in recent years due
to CT scanners with a larger field of view covering the whole myocardium in a
single rotation and the significant reduction in associated radiation dose.
This DCE-CT technique offers the potential to detect the functional
significance of stenosis similarly to PET, theoretically making it a good
alternative for Rb-82 PET. Yet studies comparing DCE-CT versus PET are scarce.
One study has quantitatively compared DCE-CT with O-15 PET7,8and another
compared DCE-CT with Rb-82 PET9. Although both showed correlation between the
quantitative MBF values, the variation in MBF using DCE-CT was relatively
large, possible due to the use of self-made, non-commercial available software.
The aim of this study is to explore how DCE-CT quantitative myocardial
perfusion assessment using commercially available software compares to Rb-82
PET and if it can be used as an alternative.

The aim of this study is to compare the myocardial flow reserve measured with
DCE-CT to the myocardial flow reserve measured with Rb-82 PET.

A single centre prospective interventional study, preceded by a learning curve
cohort.

• Patients will be asked to adhere to dietary restrictions in the 24 hours
before scanning (no caffeine), and if they have a heart rate above 65, asked to
follow an oral metoprolol preparation regimen to reduce resting heartrate.
• Patients will be asked for an additional visit (of approximately one hour) to
the Nuclear Medicine department at Isala hospital in Meppel
• Patients will undergo 2 dynamic contrast enhanced dynamic acquisitions (rest
+ coronary CTA and stress), resulting in 2 additional contrast administrations
and radiation dose of approximately 5 to 8 mSv per acquisition set, for stress
and rest acquisitions respectively, totalling approximately 13 mSv additional
radiation dose. The clinically indicated Rb-82 PET/CT scan (regular care)
results in a radiation absorbed dose of ~2.1 mSv (Isala data). The total
radiation absorbed dose of both clinically indicated Rb-82 PET/CT and the
DCE-CT is approximately 15 mSv.
• In addition, patients will have to undergo pharmacologically induced stress
for the stress CTA scan using regadenoson.

Patients receive a coronary CTA scan which they would otherwise not, allowing
their diagnosing physician to have a better anatomical understanding of the
coronary arteries and the location of potential obstruction.
The data acquired can contribute to improve the diagnostic work-up of patient
suspected of having obstructive coronary artery disease preventing the need for
special equipment such as a PET scanner and expensive Rb-82-generator and will
contribute to knowledge extension on the clinical applicability of DCE-CT.
Moreover, it may also reduce the number of negative invasive coronary
angiography procedures in centers not having PET Rb-82 equipment.