Can Dual-energy CT-based Virtual Monoenergetic Imaging Improve the Assessment of Hypodense Liver Metastases in Patients With Hepatic Steatosis?

Rationale and Objectives: To evaluate the impact of noise-optimized virtual monoenergetic imaging (VMI) on lesion demarcation and measuring accuracy of hypoattenuating liver metastases in patients with fatty liver disease compared to standard reconstructions. Materials and Methods: Twenty-eight patients (mean age 62.2 +/- 7.7 years) with fatty liver disease and hypoattenuating liver metastases who underwent unenhanced and contrast-enhanced portal-venous dual-energy CT (DECT) were enrolled. Standard linearly blended and VMI series were reconstructed in 10-keV intervals. Lesion-to-parenchyma contrast-to-noise ratio (CNR) was calculated and the best VMI series was further investigated in a subjective evaluation of overall image quality and lesion demarcation. Size measurements were per -formed independently by measuring all hypodense lesions (n = 58) twice in a predefined sequence. Inter-and intra-rater agreement was assessed using intra-class correlation coefficient (ICC) statistics. Results: The calculated CNR was greatest at 40-keV VMI (4.3 +/- 2.6), significantly higher compared to standard reconstructions (2.9 +/- 1.9; p < 0.001). Subjective ratings for overall image quality showed no significant difference between the 2 reconstruction techniques (both medians 4; p = 0.147), while lesion margin demarcation was found to be superior for 40-keV VMI (median 5; p < 0.001). Inter-(ICC, 0.98 for 40-keV VMI; ICC, 0.93 for standard reconstruction) and intra-rater (ICC, 0.99 for 40-keV VMI; ICC, 0.94 for standard image series) anal-ysis showed an excellent agreement for lesion measurements in both reconstruction techniques. Conclusion: Noise-optimized VMI reconstructions significantly improve contrast and lesion demarcation of hypoattenuating liver metas-tases in patients with the fatty liver disease compared to standard reconstruction.

Automated summary

The study evaluated the impact of noise-optimized virtual monoenergetic imaging (VMI) on lesion demarcation and measuring accuracy of hypoattenuating liver metastases in patients with fatty liver disease compared to standard reconstructions. Results showed that noise-optimized VMI reconstructions significantly improved contrast and lesion demarcation of hypoattenuating liver metastases in patients with fatty liver disease compared to standard reconstructions. Inter-and intra-rater agreement for lesion measurements was excellent for both reconstruction techniques.