Dual-energy CT with tin filter technology for the discrimination of renal lesion proxies containing blood, protein, and contrast-agent. An experimental phantom study

Abstract

PURPOSE: To differentiate proxy renal cystic lesions containing protein, blood, iodine contrast or saline solutions using dual-energy CT (DECT) equipped with a new tin filter technology (TFT). MATERIALS AND METHODS: 70 proxies (saline, protein, blood and contrast agent) were placed in unenhanced and contrast-enhanced kidney phantoms. DECT was performed at 80/140 kV with and without tin filtering. Two readers measured the CT attenuation values in all proxies twice. An 80/140 kV ratio was calculated. RESULTS: All intra-and interobserver agreements were excellent (r = 0.93-0.97; p < 0.001). All CT attenuation values were significantly higher in the enhanced than in the unenhanced setting (p < 0.05; average increase, 12.5 +/-3.6HU), while the ratios remained similar (each, p > 0.05). The CT attenuation of protein, blood and contrast agent solution differed significantly with tin filtering (p < 0.01-0.05). Significant differences were found between the ratios of protein and blood compared to contrast medium solution (each, p < 0.05) and between the ratios of protein and blood in both phantoms with tin filtering (each, p < 0.05). CONCLUSION: DECT allows discrimination between a proxy renal lesion containing contrast agent and lesions containing protein and blood through their different attenuation at 80 kV and 140 kV. Further discrimination between protein and blood containing proxies is possible when using a tin filter.Dual-Energy CT with tin filter technology for the discrimination of renal lesion proxies containing blood, protein, and contrast-agent. An experimental phantom study 1 Abstract Purpose: To differentiate proxy renal cystic lesions containing protein, blood, iodine contrast or saline solutions using dual-energy CT (DECT) equipped with a new tin filter technology (TFT). Materials and Methods:70 proxies (saline, protein, blood and contrast agent) were placed in unenhanced and contrast-enhanced kidney phantoms. DECT was performed at 80/140kV with and without tin filtering. Two readers measured the CT attenuation values in all proxies twice. An 80/140kV ratio was calculated.Results: All intra-and interobserver agreements were excellent (r=0.93-0.97; p<0.001). All CT attenuation values were significantly higher in the enhanced than in the unenhanced setting (p<0.05; average increase, 12.5±3.6HU), while the ratios remained similar (each, p>0.05). The CT attenuation of protein, blood and contrast agent solution differed significantly with tin filtering (p<0.01-0.05). Significant differences were found between the ratios of protein and blood compared to contrast medium solution (each, p<0.05) and between the ratios of protein and blood in both phantoms with tin filtering (each, p<0.05). Conclusion:DECT allows discrimination between a proxy renal lesion containing contrast agent and lesions containing protein and blood through their different attenuation at 80kV and 140kV. Further discrimination between protein and blood containing proxies is possible when using a tin filter.

Renal Masses

“…A D-value of 17.6 HU and a dual-energy ratio of 1.3 were found as most accurate cutoff point for enhancement detection [61]. Similar results were previously reported in a phantom experiment using a secondgeneration dual-source system [62]. Finally, iodine quantification in dual-energy CT seems to have a potential to reduce renal pseudoenhancement of small simple or hyperattenuating cysts (Figs.…”

Accuracy of dual-energy computed tomography for the measurement of iodine concentration using cardiac CT protocols: validation in a phantom model

“…This filter absorbs the low-energy photons thus reducing radiation dose and decreasing the spectral overlap between low- and high-energy spectra. The latter has been shown to allow for a more accurate material decomposition [9; 10] which is likely to translate into more accurate iodine quantification. This agrees well with our findings of overall slightly improved iodine measurement accuracy with second-generation DSCT compared to the first-generation DSCT.…”

Primary staging of laryngeal and hypopharyngeal cancer: CT, MR imaging and dual-energy CT

“…As a result, it may be difficult to differentiate materials of different chemical composition, such as iodine and bone or iodine-enhanced lesions and cartilage, as they have the same CT value on CT images [8,26]. This difficulty can be overcome for some materials using dual-energy CT [15,27,28] which exploits the dependence of the absorption coefficient on the energy of the X-ray spectrum, or kV setting, used for the scan [13,[29][30][31]. For example, materials such as iodine have lower CT values at high X-ray energies than at low X-ray energies, whereas fat tissue shows the opposite behavior.…”