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

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.

Full text: Eur Radiol. 2010 Aug 15.

Authors: Karlo C, Lauber A, Götti RP, Baumüller S, Stolzmann P, Scheffel H, Desbiolles L, Schmidt B, Marincek B, Alkadhi H, Leschka S.