Accuracy of iodine quantification using dual energy CT in latest generation dual source and dual layer CT

Abstract

ObjectiveTo determine the accuracy of iodine quantification with dual energy computed tomography (DECT) in two high-end CT systems with different spectral imaging techniques.MethodsFive 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.ResultsCorrelation 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).ConclusionIodine 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.Key Points• 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.

Dual‐energy CT iodine quantification for characterizing focal thyroid lesions

“…So, this technique ensures to neither disturb the post‐acquisition workflow nor require any additional time from the technologist/radiologist to generate the images. With the same kind of DECT scanner, 2 recent phantom experiments reported excellent correlation between measured and known IC (R 2 = 0.999‐1.000, P < .0001) with median measurement errors ranging from −3.3% (IQR: −4.9% to 1.5%) at 140 kVp to −4.6% (IQR: −6.0% to 3.6%) at 120 kVp . In this regard, our IC quantification results acquired using the same DECT mode equipped with a dual‐layer detector were expected to be appropriate.…”

“…Furthermore, their method to obtain this diagnostic equation combining ICs from both non‐enhanced and contrast‐enhanced CT images inevitably doubled the patients' radiation exposure. In this study, we used a recently implemented DECT scanner, which only a few studies used . This scanner achieves spectral separation using a different method from the previous fast‐kVp switching scanner in which the X‐ray tube rapidly modulates tube voltage .…”

Feasibility of multi‐contrast imaging on dual‐source photon counting detector (PCD) CT: An initial phantom study

“…However, image domain spectral denoising techniques can be applied to a DS system to reduce image noise, as have been implemented on commercial CT systems. Such algorithms have been tested in various clinical applications and been shown to be effective . The loss of co‐registration between DSCT does not necessarily cause loss of spatial resolution, because the two subsystems are synchronized with each other during acquisition, and both of them have the same spatial resolution as a single‐source CT.…”

Robust quantitative contrast‐enhanced dual‐energy CT for radiotherapy applications

“…The difference in the atomic composition of the blood from arteries and veins and from patient to patient can lead to further inaccuracy in the evaluation of HU values which could explain the bigger difference for the superior vena cava (b). The overall difference in iodine fraction can also be affected by the size of the patient since the proposed solutions are applied in the domain image. A bone segmentation is also required for applying VNC algorithms for radiotherapy applications and is therefore a limitation of the proposed methods.…”