Lumen enhancement influences absolute noncalcific plaque density on multislice computed tomography coronary angiography: ex-vivo validation and in-vivo demonstration.
OBJECTIVE
The purpose of this study was to define the in-vitro and in-vivo effects of intracoronary enhancement on the absolute density values of coronary plaques during multislice computed tomography.


METHODS
We studied seven ex-vivo left coronary artery specimens surrounded by olive oil and filled with isotonic saline and four solutions with decreasing dilutions of contrast material: control (isotonic saline), 1/200, 1/80, 1/50, and 1/20. The multislice computed tomography protocol was: slice/collimation 32 x 2 x 0.6 mm and rotation time 330 ms. The attenuation (Hounsfield units) value of atherosclerotic plaques was measured for each dilution in lumen, plaque (noncalcified coronary wall thickening), calcium, and surrounding oil. In-vivo assessment was performed in 12 patients (nine men; mean age 58.7 +/- 9.9 years) who underwent two subsequent multislice computed tomography scans (arterial and delayed) after intravenous administration of a single bolus of contrast material. The attenuation values of lumen and plaques during arterial and delayed computed tomography were compared. The results were compared with one-way analysis of variance and correlated with Pearson's test.


RESULTS
Mean lumen (45 +/- 38-669 +/- 151 HU) and plaque (11 +/- 35-101 +/- 72 HU) attenuation differed significantly (P < 0.001) among the different dilutions. The attenuation of lumen and plaque of coronary plaques showed moderate correlation (r = 0.54, P < 0.001). The mean attenuation value in vivo for the arterial and delayed phase scans differed significantly (P < 0.001) for lumen (325 +/- 70 and 174 +/- 46 HU, respectively) and plaque (138 +/- 71 and 100 +/- 52 HU, respectively).


CONCLUSIONS
Coronary plaque attenuation values are significantly modified by differences in lumen contrast densities both ex vivo and in vivo. This should be taken into account when considering the distinction between lipid and fibrous plaques.
Cademartiri
Filippo
F
Department of Radiology and Cardiology, Erasmus Medical Center, Rotterdam, The Netherlands. filippocademartiri@hotmail.com
Runza
Giuseppe
G
Palumbo
Alessandro
A
Maffei
Erica
E
Martini
Chiara
C
McFadden
Eugene
E
Somers
Pamela
P
Knaapen
Michiel
M
Verheye
Stefan
S
Weustink
Annick C
AC
Mollet
Nico R
NR
de Feyter
Pim J
PJ
Hamers
Ronald
R
Bruining
Nico
N
D000368:Aged; D000369:Aged, 80 and over; D003287:Contrast Media; D017023:Coronary Angiography; D003324:Coronary Artery Disease / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D007479:Iopamidol / Q000031:analogs & derivatives*; D008297:Male; D008875:Middle Aged; D014057:Tomography, X-Ray Computed
D003287:Contrast Media; C057937:iomeprol; D007479:Iopamidol