Kl. Wedding et al., CORONARY FLOW AND FLOW RESERVE IN CANINES USING MR PHASE DIFFERENCE AND COMPLEX DIFFERENCE PROCESSING, Magnetic resonance in medicine, 40(5), 1998, pp. 656-665
Coronary artery disease continues to be the leading cause of death for
adults in the United States. Magnetic resonance imaging (MR) has the
potential to dramatically impact the diagnosis of heart disease by non
invasively providing a wide range of anatomic and physiologic informat
ion. Previous research has shown that coronary flow, one component of
a complete examination, can be accurately measured in the left anterio
r descending artery in vivo. The current work validates MR flow measur
ements in canine circumflex arteries using transit time ultrasound as
a standard. The circumflex artery experiences greater in-plane motion
and is a more stringent test for flow measurement accuracy, This work
also compares two methods of processing MR velocity data, phase differ
ence and complex difference techniques, and examines the sources of er
ror present in the animal validation model, Phase difference processin
g with a 30% magnitude threshold best matched the mean ultrasound flow
values (30% PD = 1.04 x US + 1.49, r = 0.94), but it was very sensiti
ve to vessel boundary identification. The complex difference process w
as less sensitive to vessel boundary identification and correlated wel
l with the transit time ultrasound despite systematic underestimations
. The reasons for the discrepancies are shown to stem from a number of
possible sources including variability of the ultrasound standard, lo
w signal-to-noise ratios in the MR images, sensitivity of the MR techn
ique to vessel boundary identification, and motion artifacts in the im
ages.