Elsevier

Academic Radiology

Volume 27, Issue 7, July 2020, Pages e168-e175
Academic Radiology

Original Investigation
Measurement Reliability and Diagnostic Accuracy of Virtual Monoenergetic Dual-Energy CT in Patients with Colorectal Liver Metastases

https://doi.org/10.1016/j.acra.2019.09.020Get rights and content

Rationale and Objectives

To compare dual-energy CT virtual monoenergetic images (VMI) and standard reconstructions for reliability of quantitative size measurements and diagnostic accuracy for the detection of colorectal liver metastases (CRLM).

Materials and Methods

We retrospectively included 98 patients (mean age, 61.1±11.5 years) with colorectal cancer, of whom 49 subjects had CRLM. All patients underwent a portal-venous phase dual-energy CT examination. Standard linearly-blended reformats and 40-keV VMI were reconstructed. For both reconstruction techniques, two blinded readers performed measurements of CRLM twice in a preset sequence. Three additional radiologists independently assessed all liver lesions in terms of dignity (benign vs. malignant). Sensitivity, specificity and diagnostic accuracy were calculated on a per-patient basis using MRI as reference standard. Readers scored the suitability for metric measurements and their diagnostic confidence using 5-point Likert scales. Inter-rater agreement was evaluated using intraclass correlation coefficient (ICC).

Results

Inter-rater agreement for lesion size measurements was higher for 40-keV VMI (ICC, 0.88) compared to standard linearly-blended series (ICC, 0.80). Sensitivity and diagnostic accuracy for the detection of CRLM were significantly higher for VMI at 40-keV compared to standard reconstructions (90.6% vs. 80.6%, and 89.1% vs. 81.3%; p < 0.001). Reader scores indicated that 40-keV VMI were more suitable for metric lesion measurements and provided greater diagnostic confidence compared to standard reformats (median, 5 vs. 3, and 5 vs. 4; both p < 0.001).

Conclusion

Low-keV VMI reconstructions improve reliability of quantitative size measurements and diagnostic accuracy for the assessment of CRLM compared to standard linearly-blended images.

Section snippets

INTRODUCTION

Colorectal liver metastases (CRLM) are the most common type of distant metastases and an important life-limiting factor of patients with colorectal cancer (CRC) (1,2). The detection and precise evaluation of CRLM is crucial for accurate patient management, as intrahepatic tumor burden directly impacts individual treatment regimens (3,4). Liver resection is considered to be the only potential curative therapy option for patients with CRLM, however, only around 20% of affected patients are

Patient Population

This retrospective study received institutional review board approval with a waiver for written informed consent. We searched our Radiology Information System and Picture Archiving and Communication System to identify patients with CRC who had undergone abdominal portal-venous-phase DECT examinations between January 2017 and July 2018. The query revealed 116 patients with histologically proven CRC who were examined for baseline staging (n = 45) or follow-up imaging (n = 71). CRLM was present in

Patient Population

MRI of the liver revealed ≥5 liver metastases in 26 patients, <5 in 15 patients, and a single liver metastasis in eight patients. Bilobar hepatic tumor burden was found in 35 patients (71%). All patients underwent systemic chemotherapy. Additional local tumor therapy was performed in seven patients (transarterial chemoembolization, n = 4; microwave ablation, n = 3), while five patients were treated with hemihepatectomy. Abdominal DECT radiation metrics in portal-venous phase acquisition were

DISCUSSION

In this study, we aimed to evaluate measurement reliability and diagnostic accuracy for the assessment of hypoattenuating CRLM using standard linearly-blended and 40-keV VMI reconstructions, with MRI as the standard of reference. Our findings demonstrate significantly improved sensitivity, specificity, and diagnostic accuracy for the detection of CRLM by applying low-keV VMI image series compared to standard reconstructions. In addition, slightly increased measurement reliability was observed

Authors Contributions

Lukas Lenga: Data acquisition, manuscript preparation, manuscript editing, data analysis.

Marvin Lange: Data acquisition.

Christophe T. Arendt: Data acquisition, data analysis.

Christian Booz: Statistical analysis, manuscript review.

Ibrahim Yel: Statistical analysis, manuscript review.

Boris Bodelle: Manuscript review.

Tommaso D'Angelo: Manuscript review.

Renate M. Hammerstingl: Study design, manuscript editing.

Nicole A. Huizinga: Manuscript review, manuscript editing.

Thomas J. Vogl: Study concept,

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