Accuracy of iodine quantification using dual energy CT in latest generation dual source and dual layer CT.
OBJECTIVE
To determine the accuracy of iodine quantification with dual energy computed tomography (DECT) in two high-end CT systems with different spectral imaging techniques.


METHODS
Five tubes with different iodine concentrations (0, 5, 10, 15, 20 mg/ml) were analysed in an anthropomorphic thoracic phantom. Adding two phantom rings simulated increased patient size. For third-generation dual source CT (DSCT), tube voltage combinations of 150Sn and 70, 80, 90, 100 kVp were analysed. For dual layer CT (DLCT), 120 and 140 kVp were used. Scans were repeated three times. Median normalized values and interquartile ranges (IQRs) were calculated for all kVp settings and phantom sizes.


RESULTS
Correlation between measured and known iodine concentrations was excellent for both systems (R = 0.999-1.000, p < 0.0001). For DSCT, median measurement errors ranged from -0.5% (IQR -2.0, 2.0%) at 150Sn/70 kVp and -2.3% (IQR -4.0, -0.1%) at 150Sn/80 kVp to -4.0% (IQR -6.0, -2.8%) at 150Sn/90 kVp. For DLCT, median measurement errors ranged from -3.3% (IQR -4.9, -1.5%) at 140 kVp to -4.6% (IQR -6.0, -3.6%) at 120 kVp. Larger phantom sizes increased variability of iodine measurements (p < 0.05).


CONCLUSIONS
Iodine concentration can be accurately quantified with state-of-the-art DECT systems from two vendors. The lowest absolute errors were found for DSCT using the 150Sn/70 kVp or 150Sn/80 kVp combinations, which was slightly more accurate than 140 kVp in DLCT.


CONCLUSIONS
• High-end CT scanners allow accurate iodine quantification using different DECT techniques. • Lowest measurement error was found in scans with largest photon energy separation. • Dual-source CT quantified iodine slightly more accurately than dual layer CT.
Center for Medical Imaging - North East Netherlands, University of Groningen, University Medical Center Groningen, P.O. Box EB44, Hanzeplein 1, 9713 GZ, Groningen, The Netherlands.
Gert Jan
GJ
Pelgrim
Department of Radiology, Utrecht University Medical Center, Utrecht, The Netherlands.
Robbert W
RW
van Hamersvelt
Department of Radiology, Utrecht University Medical Center, Utrecht, The Netherlands.
Martin J
MJ
Willemink
Siemens Healthcare GmbH, Forchheim, Germany.
Bernhard T
BT
Schmidt
Siemens Healthcare GmbH, Forchheim, Germany.
Thomas
T
Flohr
Department of Radiology, Utrecht University Medical Center, Utrecht, The Netherlands.
Arnold
A
Schilham
Philips Healthcare, Best, The Netherlands.
Julien
J
Milles
Center for Medical Imaging - North East Netherlands, University of Groningen, University Medical Center Groningen, P.O. Box EB44, Hanzeplein 1, 9713 GZ, Groningen, The Netherlands.
Matthijs
M
Oudkerk
Department of Radiology, Utrecht University Medical Center, Utrecht, The Netherlands.
Tim
T
Leiner
Center for Medical Imaging - North East Netherlands, University of Groningen, University Medical Center Groningen, P.O. Box EB44, Hanzeplein 1, 9713 GZ, Groningen, The Netherlands. r.vliegenthart@umcg.nl.|Department of Radiology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands. r.vliegenthart@umcg.nl.
Rozemarijn
R
Vliegenthart
D015502:Absorptiometry, Photon / Q000379:methods / Q000592:standards; D003287:Contrast Media / Q000032:analysis; D003324:Coronary Artery Disease / Q000000981:diagnostic imaging; D006801:Humans; D007455:Iodine / Q000032:analysis*; D007485:Ioxaglic Acid / Q000032:analysis; D055414:Myocardial Perfusion Imaging / Q000379:methods / Q000592:standards; D019047:Phantoms, Imaging; D011829:Radiation Dosage; D014057:Tomography, X-Ray Computed / Q000379:methods / Q000592:standards*
D003287:Contrast Media; D007455:Iodine; D007485:Ioxaglic Acid
Absorptiometry, photon; Iodine; Myocardial perfusion imaging; Phantoms, imaging; Tomography, x-ray computed