ABSTRACT
Recent advances in multidetector computed tomography
(MDCT) technology have extended its use to the compre-
hensive evaluation of cardiovascular disease. Improvements
in temporal and spatial resolution along with wider detector
coverage have made practicable the non-invasive imaging of
the coronary artery lumen and surrounding atherosclerotic
plaque. Single center studies of the current generation of 64
slice MDCT scanners have demonstrated that MDCT non-
invasive angiography has good sensitivity and specificity for
identifying stenoses ≥50 % severity when compared to invasive angiography.1-4 Moreover, it appears that its greatest
power is in its negative predictive value, meaning its ability
to exclude coronary artery disease in those patients without
disease.5 However, it is in those patients with coronary
artery disease that the MDCT angiogram becomes more
limited in its diagnostic accuracy due to the presence of
coronary calcification and intracoronary stents.6-8
Although multidetector computed tomography pro-
vides unsurpassed non-invasive imaging of coronary ather-
osclerosis, we need to be cautious not to go back to the days
of ‘lumenography’ when the physiological significance of
stenoses was largely ignored. The invasive coronary angiog-
raphy literature has made clear that percent diameter steno-
sis is poorly correlated with vasodilatory reserve and
myocardial blood flow (MBF) measurements.9,10
Furthermore, the radionuclide myocardial perfusion
imaging (MPI) literature has demonstrated that perfusion
imaging adds valuable prognostic value above and beyond
the invasive coronary angiogram and the identification and
quantification of ischemia can risk stratify patients into
groups who will or will not benefit from invasive over med-
ical therapies.11,12
Recent evidence reveals that MDCT angiography alone
has a poor positive predictive value for identifying athero-
sclerosis contributing to ischemia.13-14 This has lead to the
development of hybrid imaging systems that combine
MDCT scanning systems with single photon emission
computed tomography (SPECT) or positron emission
tomography (PET) systems capable of acquiring the non-
invasive coronary angiogram and radionuclide MPI.