Virtual Non-Contrast Computer Tomography (CT) with Spectral CT as an Alternative to Conventional Unenhanced CT in the Assessment of Gastric Cancer

Objective: The purpose of this study was to evaluate computed tomography (CT) virtual non-contrast (VNC)spectral imaging for gastric carcinoma. Materials and
Methods: Fifty-two patients with histologically provengastric carcinomas underwent gemstone spectral imaging (GSI) including non-contrast and contrast-enhancedhepatic arterial, portal venous, and equilibrium phase acquisitions prior to surgery. VNC arterial phase (VNCa),VNC venous phase (VNCv), and VNC equilibrium phase (VNCe) images were obtained by subtracting iodinefrom iodine/water images. Images were analyzed with respect to image quality, gastric carcinoma-intragastricwater contrast-to-noise ratio (CNR), gastric carcinoma-perigastric fat CNR, serosal invasion, and enlargedlymph nodes around the lesions.
Results: Carcinoma-water CNR values were significantly higher in VNCa,VNCv, and VNCe images than in normal CT images (2.72, 2.60, 2.61, respectively, vs 2.35, p≤0.008). Carcinomaperigastricfat CNR values were significantly lower in VNCa, VNCv, and VNCe images than in normal CTimages (7.63, 7.49, 7.32, respectively, vs 8.48, p< 0.001). There were no significant differences of carcinoma-waterCNR and carcinoma-perigastric fat CNR among VNCa, VNCv, and VNCe images. There was no difference inthe determination of invasion or enlarged lymph nodes between normal CT and VNCa images.
Conclusions:VNC arterial phase images may be a surrogate for conventional non-contrast CT images in gastric carcinomaevaluation.