Quantification of Cisplatin Using a Modified 3-Material Decomposition Algorithm at Third-Generation Dual-Source...

The aim of this study was to assess the ability of third-generation dual-source dual-energy computed tomography to quantify cisplatin concentration using a 3-material decomposition algorithm in an experimental phantom.

Fifteen agarose-based phantoms containing various concentrations of iodine (0, 1.0, 2.0 mg I/mL) and cisplatin (0, 0.5, 1.0, 2.0, 3.0 mg Pt/mL) were scanned using third-generation dual-source dual-energy computed tomography at 80 kV and 150 kV with tin prefiltration. A cisplatin map was generated using the cisplatin-specific 3-material decomposition algorithm to differentiate cisplatin from iodine and agar. The computed tomography (CT) values at 80 kV, 150 kV, mixed 120 kV, and the cisplatin map were measured. Interobserver variabilities for the CT measurements on the cisplatin map were assessed using interclass correlation coefficients. Correlation between the CT values and titrated cisplatin concentrations was correlated using Spearman rank correlation analysis. To assess the influence of iodine, linear regression lines for the CT values on the cisplatin map and titrated cisplatin concentrations were compared using an analysis of covariance.

Interobserver agreement revealed almost perfect agreements (interclass correlation coefficients = 0.941-0.995). Significant and excellent positive correlations were observed between the CT values on the cisplatin map and titrated cisplatin concentrations (ρ = 0.980, P < 0.001 for all). The cisplatin map could identify the lowest cisplatin concentration of 0.5 mg Pt/mL in the presence of iodine. The iodine concentration had no significant effect on the CT measurements on the cisplatin map (P = 0.297, adjusted R = 0.993).

The cisplatin map generated from the 3-material decomposition algorithm allows quantification of a cisplatin concentration in an experimental phantom, independent of co-present iodine.