Objective and subjective comparison of virtual monoenergetic vs. polychromatic images in patients with pancreatic ductal adenocarcinoma

Abstract

Objectives The aim of this study was to assess the objective and subjective image characteristics of monoenergetic images (MEI[+]), using a noise-optimized algorithm at different kiloelectron volts (keV) compared to polyenergetic images (PEI), in patients with pancreatic ductal adenocarcinoma (PDAC). Methods This retrospective, institutional review board-approved study included 45 patients (18 male, 27 female; mean age 66 years; range, 42–96 years) with PDAC who had undergone a dual-energy CT (DECT) of the abdomen for staging. One standard polyenergetic image (PEI) and five MEI(+) images in 10-keV intervals, ranging from 40 to 80 keV, were reconstructed. Line-density profile analysis, as well as the contrast-to-noise ratio (CNR) of the tumor, the signal-to-noise ratio (SNR) of the regular pancreas parenchyma and the tumor, and the CNR of the three main peripancreatic vessels, was calculated. For subjective quality assessment, two readers independently assessed the images using a 5-point Likert scale. Reader reliability was evaluated using an intraclass correlation coefficient. Results Line-density profile analysis revealed the largest gradient in attenuation between PDAC and regular tissue in MEI(+) at 40 keV. Low-keV MEI(+)reconstructions at 40 and 50 keV increased CNR and SNR compared to PEI (40 keV: CNR 46.8 vs. 7.5; SNR Pankreas 32.5 vs. 15.7; SNR Lesion 13.5 vs. 8.6; p < 0.001). MEI(+) at 40 keV and 50 keV were consistently preferred by the observers ( p < 0.05), showing a high intra-observer 0.937 (0.92–0.95) and inter-observer 0.911 (0.89–0.93) agreement. Conclusion MEI(+) reconstructions at 40 keV and 50 keV provide better objective and subjective image quality compared to conventional PEI of DECT in patients with PDAC. Key Points • Low-keV MEI(+) reconstructions at 40 and 50 keV increase tumor-to-pancreas contrast compared to PEI. • Low-keV MEI(+) reconstructions improve objective and subjective image quality parameters compared to PEI. • Dual-energy post-processing might be a valuable tool in the diagnostic workup of patients with PDAC. Electronic supplementary material The online version of this article (10.1007/s00330-019-06116-9) contains supplementary material, which is available to authorized users.

Evaluating the Image Quality of Monoenergetic Images From Dual-Energy Computed Tomography With Low-Concentration and Low-Flow-Rate Contrast Media for the Arterials Supply to the Nipple-Areola Complex in Breast Cancer Compared With Conventional Computed Tomography Angiography

“…Recently, a noise-optimized MEI (+) reconstruction algorithm was developed to perform spatial frequency-based recombination, which results in the highest possible image contrast by reducing the image noise at lower energy levels. 32 In our study, image noise was increased in the 40 keV MEI (+) 300 group compared with that of the CTA 370 group, which is consistent with previous results. 16 However, subjectively, there was no statistically significant or clinical difference in the perceived image noise between the 2 groups, especially in the evaluation of the arteries.…”

Influence of field of view size on image quality: ultra-high-resolution CT vs. conventional high-resolution CT

“…However, the conventional HRCT and U-HRCT images were acquired almost at the same time, so that there was no difference in the quality of the cadaveric lungs between conventional HRCT and U-HRCT. A method to evaluate image quality by measuring tumor SNR has been reported [21], but SNR was not measured in this study. Because some evaluation items were not uniform (such as honeycombing, reticulation, etc.…”

Dual-source abdominopelvic computed tomography: Comparison of image quality and radiation dose of 80 kVp and 80/150 kVp with tin filter

“…The two image sets were used for modified line-density analysis [24]. The tumor was identified on 80/Sn150 images, and one reader, with 4 years of experience, positioned a line of 10 mm in length and 2 mm in width perpendicular to the tumor margins with one half of the line within the tumor and the other half within the normal tissue.…”

“…In other words, low kVp/high kVp with tin filter (Sn) CT generates low kVp, virtual noncontrast, and blended images, which are widely used in oncology [14]. In addition, virtual monochromatic images can be used to magnify the iodine contrast-to-noise ratio (CNR) to enhance the differentiation between tumor and background using DECT in oncology [15,16]. Although initial DECT revealed a three times higher radiation dose than single-energy CT [17], recent studies have demonstrated that third-generation dual-source DECTs can be performed without a radiation dose penalty or impairment of image quality compared to single-energy CT with 100-120 kVp [18,19].…”