Virtual unenhanced imaging of the liver with third-generation dual-source dual-energy CT and advanced modeled iterative reconstruction

Carlo N De Cecco; Giuseppe Muscogiuri; U Joseph Schoepf; Damiano Caruso; Julian L Wichmann; Paola M Cannaò; Christian Canstein; Stephen R Fuller; Lauren Snider; Akos Varga-Szemes; Andrew D Hardie

doi:10.1016/j.ejrad.2016.04.012

Virtual unenhanced imaging of the liver with third-generation dual-source dual-energy CT and advanced modeled iterative reconstruction

Eur J Radiol. 2016 Jul;85(7):1257-64. doi: 10.1016/j.ejrad.2016.04.012. Epub 2016 Apr 22.

Affiliations

¹ Department of Radiology and Radiological Science, Medical University of South Carolina, Charleston, SC, USA.
² Department of Radiology and Radiological Science, Medical University of South Carolina, Charleston, SC, USA; Department of Radiological Sciences, Oncology and Pathology, University of Rome "Sapienza", Rome, Italy.
³ Department of Radiology and Radiological Science, Medical University of South Carolina, Charleston, SC, USA; Division of Cardiology, Department of Medicine, Medical University of South Carolina, Charleston, SC, USA. Electronic address: schoepf@musc.edu.
⁴ Department of Radiology and Radiological Science, Medical University of South Carolina, Charleston, SC, USA; Department of Diagnostic and Interventional Radiology, University Hospital Frankfurt, Frankfurt, Germany.
⁵ Department of Radiology and Radiological Science, Medical University of South Carolina, Charleston, SC, USA; Scuola di Specializzazione di Radiodiagnostica, Università degli Studi di Milano, Milan, Italy.
⁶ Siemens Medical Solutions, Malvern, PA, USA.

PMID: 27235872
DOI: 10.1016/j.ejrad.2016.04.012

Abstract

Objectives: To compare image quality and diagnostic accuracy for the detection of liver lesions of virtual unenhanced (VU) images based on third-generation dual-source dual- energy computed tomography (DECT) compared to conventional unenhanced (CU) images.

Methods: Thirty patients underwent triphasic abdominal CT consisting of single-energy CU (120kV, 147 ref.mAs) and dual-energy CT arterial and portal-venous phase acquisitions (100/Sn150kV, 180/90 ref.mAs). VU images were generated from arterial (AVU) and portal venous (PVU) phases. CU, AVU and PVU datasets were reconstructed. Quantitative image quality analysis was performed and two abdominal radiologists independently analyzed all datasets to evaluate image quality and identify liver lesions. Radiation dose was recorded and potential radiation dose reduction was estimated.

Results: Image quality was rated diagnostic in 100% of the VU datasets. The mean subjective image quality of the CU datasets was higher than that of VU images (p<0.0001). No significant difference was observed in the mean attenuation values of the liver parenchyma (p>0.99) and hypoattenuating liver lesions (p≥0.21) between CU, AVU and PVU. However, a significant reduction in the attenuation values of calcified lesions (p<0.0001), metallic clips (p<0.0001) and gallstones (p≤0.047) was observed in the AVU and PVU images compared with CU images. A total of 122 liver lesions were found in 25 patients. VU images were more sensitive than CU images for detection of small hypoattenuating liver lesions (≤1cm). However, CU images were more sensitive than VU for calcified liver lesions. The mean radiation dose reduction achievable by avoiding the unenhanced acquisition was 32.9%±1.1% (p<0.01).

Conclusions: Third-generation DSCT VU images of the liver provide diagnostic image quality and improve small (≤1cm) liver lesion detection; however calcified liver lesions can be missed due to complete subtraction.

Keywords: Conventional unenhanced; Dual-energy CT; Image quality; Liver lesion; Radiation dose; Virtual unenhanced.

MeSH terms

Adult
Aged
Female
Humans
Image Processing, Computer-Assisted / methods*
Liver / diagnostic imaging*
Liver Diseases / diagnostic imaging*
Male
Middle Aged
Prospective Studies
Radiation Dosage
Radiographic Image Interpretation, Computer-Assisted / methods*
Radiography, Dual-Energy Scanned Projection / methods*
Reproducibility of Results
Sensitivity and Specificity
Tomography, X-Ray Computed / methods*