4D Dynamic Contrast-Enhanced Breast CT: Evaluation of quantitative accuracy

Four-dimensional dynamic contrast-enhanced breast CT (4D DCE-bCT) holds potential for high spatio-temporalresolution imaging for characterization and monitoring of breast tumors. This study presents a dedicated phantom-based evaluation of the accuracy of dynamic iodine concentration quantification in 4D DCE-bCT. A breast CT (bCT) system was adapted for extended acquisition times, and the x-ray spectrum was optimized (65 kV/0.25 mm Cu). Additionally, reconstruction and correction algorithms were developed for accurate iodine quantification. The imaging sequence involved a 10-second pre-contrast scan with 360 projections, followed by two 100-second post-contrast scans, each with 400 projection images over 10 rotations, with 10 seconds between each scan. In this experiment, we aimed to quantitatively assess the changes in iodine concentration, while a time-varying concentration of iodine (range 0.5 to 10 mg I/mL) was pumped through a 5 mm diameter tube in an olive-oil breast phantom. Pre- and post-contrast images were scatter-corrected and reconstructed using a polychromatic iterative reconstruction (IMPACT) combined with PICCS. This process yielded a 38-framevirtual monoenergetic (30 keV) image sequence at 5-second intervals. To verify the perfusion curve accuracy, a 5 × 5 × 10 voxel VOI was compared against the known true iodine concentration. Linear fits to the results showed good precision with some under-estimation of the true concentration (wash-in: slope = 0.7530, offset = +0.5208, R² = 0.985; wash-out: slope = 1.012, offset = -0.8295, R² = 0.987). These findings indicate the 4D DCE-bCT's potential to provide quantitatively accurate estimates of iodine concentration.