Primary study on the detection of hepatic tumors with spectral CT monochromatic imaging

Abstract

Objective To evaluate the effect of spectral CT monochromatic imaging on the detection of hepatic tumors. Methods Forty-two patients with hepatic tumors (14 patients with hepatocellular carcinoma, 12 patients with metastatic tumor, 16 patients with hemangioma) underwent CT spectral imaging. During arterial phase, portal phase and venous phase, 140 kVp polychromatic images and 70 keV monochromatic images were obtained. Paired-sample t tests were used to compare the image quality score,liver noise and tumor-to-liver contrast-to-noise ratio (CNR) between the two image data sets. The detection rates of various tumors during each phase were compared. Results The image quality scores of various tumors during three phases were (4. 30 ± 0. 25) and (3.63 ± 0. 22) averagely for the 70 keV and 140 kVp images. The liver noises were (8. 82 ± 0. 82) and ( 10. 66 ± 1.10) , and the CNRs were 5.39 and 3. 89,respectively. The image quality score, the liver noise and the CNR of 70 keV images were significantly greater than those of 140 kVp images (P ＜0. 05 ). The detection rates of various tumors during each phase were higher with 70 keV images (78％-100％) than with 140 kVp images (65％-96％), except the hepatic metastatic tumors and the hepatic hemangiomas during the arterial phase. The detection rate was more increased for the small lesions less than 1 cm (57％-100％ vs. 14％-91％ ). Conclusion By substantially improving the image quality and increasing the tumor-to-liver conspicuity, the 70 keV monochromatic imaging of spectral CT improves the detection of hepatic tumors and is more sensitive for the detection of small lesions. Key words: Liver neoplasms; Tomography, X-ray computed; Comparative study