Evaluation of a Novel Tantalum Oxide-Based Contrast Agent for Liver Imaging and Tumor Detection in Dual-Energy CT: A Preclinical Proof-of-Concept Study.

Rationale And Objectives: To evaluate an experimental intravascular carboxybetaine zwitterionic tantalum oxide (TaCZ) nanoparticle CT contrast agent versus iopamidol for hepatic imaging and tumor detection using a multiphase dual-layer spectral CT (DLCT).

Materials And Methods: Rabbits with small (0.6 - 0.9 cm) solitary VX2 hepatic tumors were scanned on a clinical DLCT within a human abdomen-sized encasement resulting in a total of 10 study sets. Multiphase scans were acquired before and at 6, 40, 105, and 180 s post-injection of 540 mg of contrast element (Ta or I) per kg of body weight, using either TaCZ or iopamidol. Conventional 120 kVp and 50 keV virtual monoenergetic images were reconstructed to assess liver, portal vein, and hepatic tumor enhancement. Three radiologists independently rated conspicuity and tumor detection.

Results: Iopamidol at 120 kVp showed significantly lower contrast enhancement and poorer liver, vessel and tumor conspicuity compared to 50 keV or TaCZ reconstructions (all time points; p < 0.001). TaCZ provided higher tumor contrast-to-noise ratios, conspicuity scores, and detection rates than iopamidol across all time points (p < 0.001). Differences were most pronounced at 105 and 180 s. TaCZ demonstrated consistent performance across energy levels, unlike Iopamidol.

Conclusion: TaCZ outperformed iopamidol for small liver tumor detection on DLCT, with greater diagnostic benefit at delayed phases and spectral imaging.