Dual-energy CT for hypovascular liver metastases: does better image quality translate to clinical benefit?

To assess the objective and subjective image quality of hypovascular liver metastases on dual-energy CT (DECT) at various virtual monoenergetic imaging (VMI) levels compared to conventional CT, and to determine whether DECT identifies additional lesions or alters radiation exposure.

This retrospective study included patients with hypovascular liver metastasis who underwent DECT on portal venous phase. Contrast-to-noise ratio (CNR), signal-to-noise ratio (SNR), and subjective image quality (5-point Likert scale) were analyzed. Radiation dose was compared to corresponding values from conventional CT performed on the same patients. Statistical analyses included the Friedman test for repeated measures, Wilcoxon signed-rank tests with Bonferroni correction for post-hoc comparisons, and the Mann-Whitney U test for radiation dose comparison. A p-value < 0.05 was considered statistically significant.

A total of 45 patients with 128 metastases were evaluated. VMI at 40 keV demonstrated the highest SNR (5.08) and subjective quality (median score: 5.0), significantly outperforming conventional CT (SNR: 3.90, p = 0.001). CNR was highest at 40 keV but not statistically different across reconstructions (p = 0.42). Subjective scores differed significantly among all image types (p < 0.0001). No additional lesions were detected on DECT compared to conventional CT. Radiation dose was similar between DECT and conventional CT (CTDIvol: 45.4 vs. 45.39 mGy, p = 0.688).

While DECT with low-keV VMI improves objective and subjective image quality for hypovascular liver metastases, it does not increase lesion detection compared to conventional CT. The clinical utility of DECT in this setting may be limited to enhanced reader confidence rather than diagnostic gain.