Effect of a saline flush technique for head and neck imaging in dual-energy CT: improvement of image quality and perivenous artefact reduction using virtual monochromatic imaging.

To evaluate the effect of the saline flush (SF) technique on the depiction of lesions and the reduction of perivenous artefacts in the head and neck region using dual-energy computed tomography (CT) with virtual monochromatic imaging (VMI). Fifty patients with head and neck cancer were divided into two groups: group A, without a SF and group B, with a 30-ml SF. All images were acquired using fast kilovolt-switching CT (Revolution HD, GE Healthcare, Milwaukee, WI, USA). Contrast-to-noise ratios (CNRs) of the lesions were calculated at VMI energy levels ranging from 40 to 80 keV. Subjective analysis of overall image quality, delineation of lesions, and perivenous artefacts was conducted by two reviewers at both VMI energy level 40 keV and the optimal energy level (which showed optimal CNR by objective analysis). Optimal energy level was 63 keV for group A and 61 keV for group B. At VMI energy levels ranging from 40 to 80 keV, the CNR was higher for group B. The highest subjective overall image quality was shown for group B at the optimal energy level (subjective image quality mean value, 3.40). Subjective delineation of lesions was comparable. The perivenous artefact score was significantly higher for group B (2.44 versus 2.74 [p<0.05] at 40 keV, 3.20 versus 3.46 [p<0.05] at the optimal energy level). The SF technique results in an improvement of lesion CNR and a reduction of perivenous artefacts in VMI using duel-energy CT, especially at 40 keV.

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