[Dual energy CT of the peripheral arteries: a phantom study to assess the effect of automatic plaque removal on stenosis grading].
OBJECTIVE
To evaluate the accuracy of dual energy (DE)-based plaque removal in a vessel phantom.


METHODS
Acrylic vessel phantoms of different diameters (3, 5, 8 mm), degrees of stenoses (25 - 100%) and plaque densities (300 - 750 HU) were filled with contrast-enhanced blood (150 - 450 HU). Dual source CT was used for simultaneous image acquisition at 80 and 140 kV. Beside a DE-based plaque-subtracted dataset (DE-PS), a virtual 120 kV non-plaque subtracted dataset (N-PS) was generated. Agreement between the known and measured luminal diameter in both datasets was determined using Lin's concordance correlation coefficient (kappaLin).


RESULTS
A total of 8260 measurements were taken. The correlation of measured diameter in DE-PS images was excellent (kappaLin = 0.83 - 0.96) for 5 - 8 mm vessel phantoms with high luminal enhancement (300 - 450 HU) and plaque density (500 - 750 HU), moderate (kappaLin = 0.6 - 0.67) for 5 mm vessels with lower luminal enhancement and plaque density and poor (kappaLin = 0.10 - 0.64) in the 3 mm vessels. The correlation of N-PS-based stenosis quantification was excellent (kappaLin = 0.86 - 0.99) for 5 - 8 mm vessel phantoms if the contrast between lumen and plaque was above 100 HU. The correlation decreased in 3 mm vessels (kappaLin = 0.45 - 0.93), while the lowest correlation was observed for the lowest contrast between plaque and vessel lumen.


CONCLUSIONS
Automatic DE-based plaque removal is highly effective for heavily calcified plaques and high luminal enhancement in larger diameter vessels > or = 5 mm). However, accuracy is limited for low density calcified plaque, lower luminal enhancement and smaller caliber vessels mainly due to poor specificity.
Werncke
T
T
Klinik und Hochschulambulanz für Radiologie und Nuklearmedizin, Charité Universitätsmedizin Berlin, Campus Benjamin Franklin, Berlin. Thomas.Werncke@charite.de
Albrecht
T
T
Wolf
K-J
KJ
Meyer
B C
BC
D000465:Algorithms; D000792:Angiography / Q000379:methods*; D001157:Arterial Occlusive Diseases / Q000000981:diagnostic imaging*; D050197:Atherosclerosis / Q000000981:diagnostic imaging*; D002114:Calcinosis / Q000000981:diagnostic imaging; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D016491:Peripheral Vascular Diseases / Q000000981:diagnostic imaging*; D019047:Phantoms, Imaging; D015900:Radiography, Dual-Energy Scanned Projection / Q000379:methods*; D012680:Sensitivity and Specificity; D013223:Statistics as Topic; D013382:Subtraction Technique; D036542:Tomography, Spiral Computed / Q000379:methods*