Background: Liver metastases limit survival in colorectal cancer. Earlier detection of (occult) metastatic disease may benefit treatment and survival. Objective: The objective of this article is to evaluate the potential of whole-liver CT texture analysis of apparently diseasefree liver parenchyma for discriminating between colorectal cancer (CRC) patients with and without hepatic metastases. Methods: The primary staging CT examinations of 29 CRC patients were retrospectively analysed. Patients were divided into three groups: patients without liver metastases (n ¼ 15), with synchronous liver metastases (n ¼ 10) and metachronous liver metastases within 18 months following primary staging (n ¼ 4). Whole-liver texture analysis was performed by delineation of the apparently non-diseased liver parenchyma (excluding metastases or other focal liver lesions) on portal phase images. Mean grey-level intensity (M), entropy (E) and uniformity (U) were derived with no filtration and different filter widths (0.5 ¼ fine, 1.5 ¼ medium, 2.5 ¼ coarse). Results: Mean E 1.5 and E 2.5 for the whole liver in patients with synchronous metastases were significantly higher compared with the non-metastatic patients (p ¼ 0.02 and p ¼ 0.01). Mean U 1.5 and U 2.5 were significantly lower in the synchronous metastases group compared with the non-metastatic group (p ¼ 0.04 and p ¼ 0.02). Texture parameters for the metachronous metastases group were not significantly different from the non-metastatic group or synchronous metastases group (p > 0.05), although -similar to the synchronous metastases group -there was a subtle trend towards increased E 1.5 , E 2.5 and decreased U 1.5 , U 2.5 values. Areas under the ROC curve for the diagnosis of synchronous metastatic disease based on the texture parameters E 1.5,2.5 and U 1.5,2.5 ranged between 0.73 and 0.78. Conclusion: Texture analysis of the apparently non-diseased liver holds promise to differentiate between CRC patients with and without metastatic liver disease. Further research is required to determine whether these findings may be used to benefit the prediction of metachronous liver disease.

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Objectives: Renal lesions are sometimes incidentally detected during computed tomography (CT) examinations in which an unenhanced series is not included, preventing the lesions from being fully characterized. The aim of this study was to investigate the feasibility to use virtual non-contrast (VNC) images, acquired using a detector based dual-energy CT, for the characterization of renal lesions. Methods: Twenty-seven patients (12 women) underwent a renal CT scan, including a non-contrast, an arterial and a venous Phase contrast-enhanced series, using a detector-based dual-energy CT scanner. VNC images were reconstructed from the venous contrast-enhanced series. The mean attenuation values of 65 renal lesions in both the VNC and true non-contrast (TNC) images were measured and compared quantitatively. Three radiologists blindly assessed all lesions using either VNC or TNC images in combination with contrast-enhanced images. Results: Sixteen patients had cystic lesions, five had angiomyolipoma (AML), and six had suspected renal cell carcinomas (RCC). Attenuation values in VNC and TNC images were strongly correlated (ρ = 0.7, mean difference −6.0 ± 13 HU). The largest differences were found for unenhanced high-attenuation lesions. Radiologists classified 86% of the lesions correctly using VNC images. Conclusions: In 70% of the patients, incidentally detected renal lesions could be accurately characterized using VNC images, resulting in less patient burden and a reduction in radiation exposure. Advances in knowledge: This study shows that renal lesions can be accurately characterized using VNC images acquired by detector-based dual-energy CT, which is in agreement with previous studies using dual-source and rapid X-ray tube potential switching technique.