Abstract
This retrospective study was aimed to evaluate the reduced iodine load on image quality and diagnostic performance in multiphasic hepatic CT using a novel monoenergetic reconstruction algorithm (nMERA) in assessment of local tumor progression after radiofrequency ablation (RFA) of hepatocellular carcinoma (HCC). Ninety patients who underwent CT 1 month after RFA of HCC. Forty-five patients had multiphasic hepatic dual-energy CT with a half-reduced contrast medium (HRCM) of 277.5 mg I/kg. The nMERA (40–70-keV) images were reconstructed in each phase. Another 45 patients received a standard contrast medium (SCM) of 555 mg I/kg, and the images were reconstructed as a simulated 120-kVp images. Primary outcome was accuracy, sensitivity, specificity, and area under the receiver operating characteristic curve (AUC) in assessment of local tumor progression. Additional advanced assessments included the image noise, attenuation value, contrast-to-noise ratio (CNR), and subjective image quality between the groups. The accuracy, sensitivity and specificity of nMERA HRCM images were 95.7%, 100% and 93.9% for 40 keV, 95.7%, 85.7% and 100% for 50 keV, 83.0%, 42.8% and 100% for 60 keV, and 83.0%, 42.9% and 100% for 70 keV. The AUROC was 0.99, 0.99, 0.94, and 0.93 for 40–70 keV nMERA HRCM images, respectively. Compared with simulated 120-kVp SCM images, nMERA HRCM images demonstrated comparable noise at 70-keV (P < 0.05), and comparable CNR at 40- and 50-keV (P < 0.05). nMERA DECT enables the contrast medium to be reduced to up to 50% in multiphasic hepatic CT while preserving diagnostic accuracy.
Highlights
Multidetector computed tomography (CT) is widely applied clinically
Our study results showed that compared with simulated 120-kVp linear blended images at standard contrast medium (SCM), low-energy novel monoenergetic reconstruction algorithm (nMERA) half-reduced contrast medium (HRCM) images preserved vascular and visceral contrast enhancement and diagnostic performance, and high-energy nMERA HRCM images demonstrated adequate image quality. This finding is of practical importance because it demonstrates that multiphasic hepatic CT can be performed at a lower contrast medium (CM) dose without compromising on diagnostic performance
Lv et al [5] used rapid kV switching dualenergy CT (DECT) to produce virtual monochromatic images (VMI) in abdominal CT, and they revealed that compared with 120-kVp images reconstructed using the filtered back projection algorithm, 50-keV VMI reconstructed using the iterative reconstruction algorithm enabled CM dose reduction and adequate image quality and lesion conspicuity
Summary
Multidetector computed tomography (CT) is widely applied clinically. the concerns of radiation exposure, contrast medium-induced nephropathy (CIN), and the dose of contrast medium (CM) have been raised considering that CT is a commonly used tool for disease. The quality of images obtained at the low tube voltage of single-energy CT with an iterative reconstruction algorithm and at a reduced CM dose was not inferior compared with that of conventional 120-kVp images [4, 7, 8, 12, 13]. In DECT, a novel monoenergetic reconstruction algorithm (nMERA) was introduced to optimize image quality at low keV levels, providing markedly increased iodine contrast with moderate noise [18,19,20,21]. This application has not been investigated for CM dose reduction in abdominal CT. We evaluated the application of nMERA and the half-reduced CM dose in assessment of local tumor progression after radiofrequency ablation (RFA) of hepatocellular carcinoma (HCC), and we aimed to determine the optimal energy level
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