Purpose: To evaluate the accuracy of dual-energy CT iodine quantification comparing three different CT models from the a manufacturer, with two phantoms.
Methods: Two phantoms (one with two setups to evaluate the effect of body habitus) with various nominal known iodine concentration inserts (0.5 to 15 mg/ml, and 2, 4 mg/ml mixed with blood mimicking materials) and other tissue/organ mimicking inserts were scanned with three Siemens CT scanners (Drive, X.cite and Force) that have two different dual-energy mechanisms, using clinically used abdomen/pelvis dual-energy scanning protocols, with different kilovolt peak or energy spectral separation settings and with automatic tube current modulation employed. Scans were performed with different insert locations in one phantom. Iodine concentration measurements were made on the images generated on Siemens Syngo.via. Linearity of measured iodine concentrations with nominal known insert concentrations were assessed. The absolute iodine concentration difference between aforementioned two were also analyzed.
Results: Measured iodine concentrations from all three scanners are linear with nominal known iodine concentrations, with R² values between 0.9935 and 1. Among three scanners, absolute difference on iodine concentrations measured from two phantoms ranged from -1.8 to 0.7 mg/ml and from -1.5 to 1.6 mg/ml, respectively, with one scanner outperformed the other two on one phantom. Accuracy of iodine quantification was degraded prominently at 10 and 15 mg/ml on two scanners, especially when these inserts were placed in the periphery of the phantom that mimics large body habitus. One scanner showed notable degradation on contrast-enhance blood iodine concentration, while one scanner showed slight improvement, when those inserts were placed in the large-sized phantom.
Conclusion: There’s general agreement on iodine quantification accuracy with notable variations among three scanners from the same manufacturer. Locations of the iodine inserts and size of the phantom resulted in different accuracy of iodine quantification.
Dual-energy Imaging, Contrast, CT