New non-invasive technique uses CT for testing heart function
25 October 2011
A new non-invasive technique for measuring how well the heart
and blood vessels function in patients already suffering from coronary
artery disease could, in a single test, identify which abnormally
narrowed blood vessels are the most likely to lead to further
cardiovascular complications.
According to Dr. Aaron So, at Lawson Health Research Institute and
Robarts Research Institute in London, Canada, and colleagues, their
technique could reveal functional problems in the circulatory system
below the limit of detection of the currently most sensitive method,
invasive angiography (or blood vessel x-ray). The work is published
online in Springer's journal European Radiology.
Dr So and colleagues developed a quantitative non-invasive method
— Dynamic Contrast-Enhanced CT (DCE-CT) with quantitative CT
perfusion analysis — to assess the functional relevance of coronary
artery stenosis, or abnormal narrowing of blood vessels ie which are
the most likely to cause problems for patients in the future.
Coronary stenoses that limit blood flow during exercise or
drug-induced vasodilation diminish the amount of blood available to
the cardiovascular system and are therefore likely to lead to
significant coronary lesions.
A total of twenty-six 53- to 71-year-old patients with existing
coronary artery disease took part in the study. The researchers
assessed the degree of stenosis in their coronary arteries and
classified them into one of four categories: non stenosed;
moderately stenosed; severely stenosed; and severely stenosed with
blood fed from an adjacent coronary artery.
They then used their new DCE-CT technique to measure 'myocardial
perfusion reserve' and 'myocardial volume reserve' — measures of
blood flow during maximum coronary vessel dilation induced by
exercise or drugs — and calculate the ratio of the two and its
relationship with coronary stenosis classification.
Their results show that the ratio of 'myocardial perfusion
reserve' to 'myocardial volume reserve' is the best predictor of
severe stenosis. The new technique demonstrates an excellent
sensitivity, able to detect 50% or greater narrowing of the coronary
arteries.
The authors conclude: "This new technique could play an important
role in the evaluation of the likelihood of future cardiac events in
patients with intermediate to advanced risk of coronary artery
disease, allowing timely and appropriate intervention.”
Further information
So A, et al (2011). Non-invasive assessment of
functionally relevant coronary artery stenoses with quantitative CT
perfusion: preliminary clinical experiences. European Radiology,
DOI 10.1007/s00330-011-2260-x.