Abdominal Imaging - Original Article
Dual-Energy CT characteristics of colon and rectal cancer allows differentiation from stool by dual-source CT
Department of Radiology, Hacettepe University School of Medicine, Ankara, Turkey
Department of Gastroenterology, Hacettepe University School of Medicine, Ankara, Turkey
Department of General Surgery, Hacettepe University School of Medicine, Ankara, Turkey
Diagn Interv Radiol ; : -
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Purpose: To determine dual-energy computed tomography (DECT) characteristics of colorectal cancer and investigate effectiveness of DECT method in differentiating tumor from stool in patients with colorectal cancer.
Material and methods: Fifty consecutive patients with colorectal tumors were enrolled. Staging computed tomography (CT) was performed by DECT method (80-140kV) using dual-source CT after rectal air insufflation and without bowel preparation. Both visual and quantitative analyses were performed on 80kV, 140kV, iodine map and virtual non-contrast (VNC) images.
Results: All colorectal tumors had homogeneous pattern on iodine map. Stools demonstrated heterogeneous pattern in 86% (43/50) and homogeneous pattern in 14% (7/50) on iodine maps and were less visible on VNC images. Median density of tumors was 54 (18 – 100) HU and 28 (11 – 56) HU on iodine map and VNC images, respectively. Median density of stool was 36.5 (8 – 165) HU and -135.5 (-438 – -13) HU on iodine map and VNC images, respectively. The density of stools was significantly lower than tumors on both iodine map and VNC images (P < 0.001). The cut-off point of density measurement on VNC images was -1 HU with area under the curve of 1, a sensitivity and specificity of 100.0%.
Conclusion: Density or visual analysis of iodine map and VNC DECT images allows accurate differentiation of tumor from stool.