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Objective: This study aimed to investigate the application value of virtual monoenergetic (VMI) (≤70 keV) computed tomography angiography (CTA) in imaging small cerebral vessels with dual-layer detector spectral CT. Methods: The imaging data of 52 patients who underwent head and neck CTA using Philips IQon CT were retrospectively analyzed. Conventional 120 kVp mixed energy images and 40~70 keV (10 keV interval) VMI CTA images reconstructed using spectral data were obtained. The CT value, signal-to-noise ratio (SNR), contrast noise ratio (CNR), and CT value and noise (SD) of the paravascular cerebral parenchyma at the same level were measured in the M1 segment of the middle cerebral artery. The image quality of the middle cerebral artery in volume reconstruction (VRT) and lepidopleural artery in maximum density projection (MIP) was scored by two physicians using a 5-point Likert scale. The evaluation results between the different groups were compared. Results: The CT, SNR, and CNR values of blood vessels at 40~70 keV VMI increased with a decrease in energy level, and the SD values increased slightly, with more statistically significant differences compared with conventional images. In the subjective evaluation, the VRT images in the 40 keV and 50 keV groups were 5 (5, 5) and 5 (4, 5), respectively, and the MIP image scores were 4 (3, 4) and 4 (3, 5), respectively. The subjective scores of both groups were better than those of the other groups, with no statistically significant difference. Conclusion: Virtual monoenergetic CTA technology with dual-layer spectral CT

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Objective: To assess the diagnostic value of spectral parameters in differentiating adrenal adenomas from metastases based on dual-layer detector spectral CT (DLSCT). Materials and methods: Patients with adenomas or metastases who underwent enhanced DLSCT of the adrenals were enrolled. The CT values of virtual non-contrast images (CTVNC), iodine density (ID) values, and Z-effective (Z-eff) values, the normalized iodine density (NID) values, slopes of spectral HU curves (s-SHC), and iodine-to-CTVNC ratios of the tumors were measured in each phase. Receiver operating characteristic (ROC) curves were used to compare the diagnostic values. Results: Ninety-nine patients with 106 adrenal lesions (63 adenomas, 43 metastases) were included. In the venous phase, all spectral parameters were significantly different between adenomas and metastases (all p < 0.05). The combined spectral parameters showed a better diagnostic performance in the venous phase than in other phase (p < 0.05). The iodine-to-CTVNC value had a larger area under the ROC curve (AUC) than the other spectral parameters in the differential diagnosis of adenomas and metastases, with a diagnostic sensitivity and specificity of 74.4% and 91.9%, respectively. In the differential diagnosis of lipid-rich adenomas, lipid-poor adenomas and metastases, the CTVNC value and s-SHC value also had a larger AUC than the other spectral parameters, with a diagnostic sensitivity of 97.7%, 79.1% and specificity of 91.2%, 93.1%, respectively. Conclusion: On DLSCT, the combined spectral parameters in the venous phase could help better distinguish adrenal adenomas from metastases. The iodine-to-CTVNC, CTVNC and s-SHC values had the highest AUC values in differentiating adenomas, lipid-rich adenomas and lipid-poor adenomas from metastases, respectively. [ABSTRACT FROM AUTHOR]

Copyright of Chinese Medical Equipment Journal is the property of Chinese Medical Equipment Journal Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Objective To explore the optimal parameters for virtual mono-energetic imaging of liver solid lesions. Methods A retrospective analysis was performed on 60 patients undergoing contrast-enhanced spectral CT of the abdomen.The iodine concentration values of hepatic arterial phase images and the CT values of different mono-energetic images were measured.The correlation coefficient and coefficient of variation were calculated. Results The average correlation coefficients between iodine concentrations and CT values of hepatic solid lesion images at 40,45,50,55,60,65,and 70 keV were 0.996,0.995,0.993,0.989,0.978,0.970,and 0.961,respectively.The correlation coefficients at 40( P =0.007),45( P =0.022),50 keV ( P =0.035)were higher than that at 55 keV,and the correlation coefficients at 40 keV( P =0.134) and 45 keV( P =0.368) had no significant differences from that at 50 keV.The coefficients of variation of the CT values at 40,45,and 50 keV were 0.146,0.154,and 0.163,respectively. Conclusion The energy of 40 keV is optimal for virtual mono-energetic imaging of liver solid lesions in the late arterial phase,which is helpful for the diagnosis of liver diseases.

Objective To evaluate the effect of monochromatic energy image on inferior vena cava imaging quality on dual-layer detector spectral CT. Methods Totally 39 patients who were clinically suspected of abdominal disease and referred to perform contrast-enhanced computed tomography(CT)were prospectively enrolled and underwent abdominal examination using a single-source,dual-detector spectral CT.The delayed phase scan was performed 3 minutes after injection of 60 ml of iopamidol(320 mg/ml)at a rate of 3 ml/s.The raw images were reconstructed to obtain conventional mixed energy images and spectral based images(SBI).The 40,50,60,and 70 keV single energy images were obtained.The CT value,noise,and signal-to-noise(SNR)of inferior vena cava and the contrast-to-noise(CNR)of inferior vena cava relative to psoas major on conventional mixed energy images and the 40,50,60,70 keV single energy images were measured.The SNRs and CNRs on monoenergetic 40-70 keV images were compared with polychromatic 120 kVp images.ANOVA was used to compare the CT value,noise,SNR,and CNR among these five groups.The optimal monoenergetic image set was chosen. Results The differences in CT value,noise,SNR,CNR of inferior vena cava were statistically significant among five groups(all P <0.05).The SNR and CNR in 40 keV group and 50 keV group were significantly higher than those in other groups(all P <0.05).The SNR of 40 keV group was significantly higher than that of 50 keV group( P =0.002).The CNR of 40 keV group was not statistical different compared with that of 50 keV group( P =0.630). Conclusion 40 keV is the optimal monoenergetic energy level for the inferior vena cava on dual-layer detector spectral CT and may be valuable for the diagnosis of inferior vena cava disease.