Spectral CT: Preliminary Studies in the Liver Cirrhosis

Department of Radiology, The First Affiliated Hospital of Zhengzhou University, Henan Province 450052, China.
Korean journal of radiology: official journal of the Korean Radiological Society (Impact Factor: 1.57). 07/2012; 13(4):434-42. DOI: 10.3348/kjr.2012.13.4.434
Source: PubMed


To investigate the value of spectral CT imaging in the diagnosis and classification of liver cirrhosis during the arterial phase (AP) and portal venous phase (PVP).
Thirty-eight patients with liver cirrhosis (Child-Pugh class A/B/C: n = 10/14/14), and 43 patients with healthy livers, participated in this study. The researchers used abdominal spectral CT imaging during AP and PVP. Iodine concentration, derived from the iodine-based material-decomposition image and the iodine concentration ratio (IC(ratio)) between AP and PVP, were obtained. Statistical analyses {two-sample t test, One-factor analysis of variance, and area under the receiver operating characteristic curve (A [z])} were performed.
The mean normalized iodine concentration (NIC) (0.5 ± 0.12) during PVP in the control group was significantly higher than that in the study group (0.4 ± 0.10 on average, 0.4 ± 0.08 for Class A, 0.4 ± 0.15 for Class B, and 0.4 ± 0.06 for Class C) (All p < 0.05). Within the cirrhotic liver group, the mean NIC for Class C during the AP (0.1 ± 0.05) was significantly higher than NICs for Classes A (0.1 ± 0.06) and B (0.1 ± 0.03) (Both p < 0.05). The IC(ratio) in the study group (0.4 ± 0.15), especially for Class C (0.5 ± 0.14), was higher than that in the control group (0.3 ± 0.15) (p < 0.05).The combination of NIC and IC(ratio) showed high sensitivity and specificity for differentiating healthy liver from cirrhotic liver, especially in Class C cirrhotic liver.
Spectral CT Provides a quantitative method with which to analyze the cirrhotic liver, and shows the potential value in the classification of liver cirrhosis.

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    • "This is vitally important in imaging liver fibrosis, which requires quantification of a number of different tissue types including healthy liver tissue, fibrotic liver tissue, blood, and contrast agent. Furthermore, DECT has been shown to be a quantitative method to analyze the cirrhotic liver with high sensitivity and specificity [28], demonstrating potential application to the fibrotic liver as well. Moreover, DECT does not bring additional dose to the patient, operating within the limits specified by the American College of Radiology guidelines for abdominal CT [27], and has even demonstrated performance at or above the standards set by conventional CT [29]. "
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    ABSTRACT: Assessing the severity of liver fibrosis has direct clinical implications for patient diagnosis and treatment. Liver biopsy, typically considered the gold standard, has limited clinical utility due to its invasiveness. Therefore, several imaging-based techniques for staging liver fibrosis have emerged, such as magnetic resonance elastography (MRE) and ultrasound elastography (USE), but they face challenges that include limited availability, high cost, poor patient compliance, low repeatability, and inaccuracy. Computed tomography (CT) can address many of these limitations, but is still hampered by inaccuracy in the presence of confounding factors, such as liver fat. Dual-energy CT (DECT), with its ability to discriminate between different tissue types, may offer a viable alternative to these methods. By combining the "multi-material decomposition" (MMD) algorithm with a biologically driven hypothesis we developed a method for assessing liver fibrosis from DECT images. On a twelve-patient cohort the method produced quantitative maps showing the spatial distribution of liver fibrosis, as well as a fibrosis score for each patient with statistically significant correlation with the severity of fibrosis across a wide range of disease severities. A preliminary comparison of the proposed algorithm against MRE showed good agreement between the two methods. Finally, the application of the algorithm to longitudinal DECT scans of the cohort produced highly repeatable results. We conclude that our algorithm can successfully stratify patients with liver fibrosis and can serve to supplement and augment current clinical practice and the role of DECT imaging in staging liver fibrosis.
    IEEE Transactions on Medical Imaging 08/2014; 34(3). DOI:10.1109/TMI.2014.2353044 · 3.39 Impact Factor
  • P Lv · J Liu · R Wu · P Hou · L Hu · J Gao
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    ABSTRACT: To evaluate the image quality of dual-energy abdominal computed tomography (DECT) angiography (CTA) with a non-linear image blending technique as compared with the linear image blending technique and standard single-energy CT (SECT; 120 kVp SECT) imaging. Thirty-two patients underwent dual-source, dual-energy abdominal CTA (80 kVp/140 kVp mode) in the arterial phase to generate non-linear image blending and 0.5 linear image blending images. Abdominal vessel enhancement, image noise, signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were evaluated and compared to the conventional 120 kVp SECT image sets (n = 29) using repeated-measures analysis of variance (ANOVA) with Bonferroni adjustment. Two radiologists assessed subjective vessel enhancement in consensus. The effective dose was calculated and compared using Student's t-test. The non-linear image blending images were ranked highest (over 0.5 linear image blending and 120 kVp SECT images) regarding mean vascular attenuation, CNR, SNR, and subjective image quality evaluation (p-values ranging from <0.001-0.021). However, there was no significant difference in renal artery branch visualization among the three sets of images (p = 0.405). Linear image blending images showed improved vascular attenuation (p = 0.011) as compared with 120 kVp SECT images, but displayed similar results regarding CNRs (p = 0.045) and SNRs (p = 0.053). The effective radiation dose for the DECT protocol was much lower than the SECT protocol (p = 0.004). The non-linear image blending technique of 80 kVp/140 kVp DECT improved vascular visualization by improving contrast enhancement in abdominal CTA during the arterial phase.
    Clinical Radiology 11/2013; 69(2). DOI:10.1016/j.crad.2013.09.019 · 1.76 Impact Factor
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    ABSTRACT: Objective: 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. Subjects and methods: 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. Results: 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. Conclusion: 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.
    American Journal of Roentgenology 09/2014; 203(3):601-6. DOI:10.2214/AJR.13.11337 · 2.73 Impact Factor
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