Liver enhancement using rapid kVp-switching dual-energy CT with reduced iodine contrast dose compared with single-energy CT with standard iodine dose: an intra-patient comparison.

Purpose: To compare liver parenchymal enhancement and tumor washout on portal and delayed phases between rapid kVp-switching dual-energy CT (DECT) with a low-iodine-dose (LID) contrast medium protocol (350 mg/kg) and conventional single-energy CT (SECT) with a standard-iodine-dose protocol (525 mg/kg), in patients referred for primary liver cancer.

Materials And Methods: All consecutive patients referred for primary liver cancer assessment who underwent both SECT with standard iodine dose and DECT with LID protocol were retrospectively reviewed. Relative Liver Enhancement (RLE) and parenchymal contrast-to-noise ratio (pCNR) on portal venous (PVP) and delayed phases were compared between 50 keV virtual monochromatic DECT and SECT images. A sub-analysis at 77 keV was also performed. Quantitative tumor enhancement (QTE) and tumoral contrast-to-noise ratio (tCNR) were compared between techniques in a subset of patients bearing LI-RADS 5 liver tumors.

Results: Seventy-seven patients (mean age 66±9 years) were included and 154 CT scans were analyzed (February 2023-October 2023). RLE and pCNR were significantly higher on 50-keV DECT than on SECT during both PVP (RLE: 1.68 ± 0.45 vs. 0.82 ± 0.18; pCNR: 2.90 ± 1.01 vs. 2.54 ± 0.76; all p < 0.01) and delayed phases (RLE: 1.17 ± 0.41 vs. 0.61 ± 0.19; pCNR: 1.84 ± 0.90 vs. 1.61 ± 0.67; p < 0.05). At 77 keV, RLE and pCNR were similar to SECT. Among thirty-one LR-5 tumors (n = 17 patients), QTE and tCNR were significantly greater on 50-keV DECT than SECT across all phases including PVP (-29.48 ± 16.4 vs. -13.38 ± 11.98 p < 0.001) and delayed phase (-23.48 ± 13.43 vs. -8.14 ± 10.49 p < 0.001).

Conclusion: Rapid kVp-switching DECT at 50-keV DECT VMIs improves liver and tumor contrast on PVP and delayed phase despite a 33% iodine dose reduction, supporting its use in cirrhotic patients.