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.