Dual-Energy Liver CT: Effect of Monochromatic Imaging on Lesion Detection, Conspicuity, and Contrast-to-Noise Ratio of Hypervascular Lesions on Late Arterial Phase

• Published in: American journal of roentgenology (1976) Vol. 203; no. 3; pp. 601 - 606
• Main Authors: Shuman, William P., Green, Douglas E., Busey, Janet M., Mitsumori, Lee M., Choi, Eunice, Koprowicz, Kent M., Kanal, Kalpana M.
• Format: Journal Article
• Language: English
• Published: United States 01.09.2014
• Subjects: Female; Humans; Liver Cirrhosis - complications; Liver Cirrhosis - diagnostic imaging; Liver Neoplasms - blood supply; Liver Neoplasms - diagnostic imaging; Liver Neoplasms - etiology; Male; Middle Aged; Neovascularization, Pathologic - diagnostic imaging; Neovascularization, Pathologic - etiology; Observer Variation; Portal Vein - diagnostic imaging; Precancerous Conditions - diagnostic imaging; Radiographic Image Enhancement - methods; Radiographic Image Interpretation, Computer-Assisted - methods; Radiography, Dual-Energy Scanned Projection - methods; Reproducibility of Results; Sensitivity and Specificity; Signal-To-Noise Ratio; Tomography, X-Ray Computed - methods; dual-energy CT; fast kilovoltage switching; cirrhosis; hepatocellular carcinoma; liver CT
• ISSN: 0361-803X; 1546-3141; 1546-3141
• DOI: 10.2214/AJR.13.11337

The purpose of this study was to evaluate the effect of use of dual-energy CT monochromatic imaging in the late hepatic arterial phase on hyperenhancing focal lesion detection and lesion conspicuity. This prospective study included 72 patients imaged with a single-source dual-energy CT scanner. Late arterial phase imaging was performed with dual energies of 140 and 80 kVp, and the portal venous and delayed phases were performed with a single energy of 120 kVp. Two deidentified image sets were created: set A consisted of 77-keV images only, and set B consisted of 40-, 50-, 70-, and 77-keV images and iodine-based contrast material decomposition images. Two independent reviewers identified hypervascular lesions and subjectively scored lesion conspicuity. Contrast-to-noise ratios were calculated, and radiation dose (volume CT dose index) was recorded. The 128 lesions identified had a mean size of 1.7 ± 1.4 cm. There was no difference in lesion detection between the two reviewers or the two image sets. The contrast-to-noise ratio at 50 keV was 72% greater than that at 77 keV (p < 0.0001). Subjective conspicuity was statistically greatest at 50 keV (p < 0.0001). There was no statistical difference in mean volume CT dose index between the dual-energy (12.8 mGy) and the two single-energy (14.4 and 14.2 mGy) phases. Viewing dual-energy CT images may result in the greatest subjective lesion conspicuity and measured contrast-to-noise ratio at 50 keV with equal detection of hyperenhancing liver lesions compared with viewing 77-keV images alone. In addition, the radiation doses of dual-energy CT may be similar to those of single-energy CT.