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Interscanner and Intrascanner Comparison of Virtual Unenhanced Attenuation Values Derived From Twin Beam Dual-Energy and Dual-Source, Dual-Energy Computed Tomography

Obmann, Markus M., MD*,†; Kelsch, Vanessa*; Cosentino, Aurelio, MD; Hofmann, Verena, MD*; Boll, Daniel T., MD*; Benz, Matthias R., MD*

doi: 10.1097/RLI.0000000000000501
Original Articles

Objective The aim of the current study was to evaluate the reliability and comparability of virtual unenhanced (VUE) attenuation values derived from scans of a single-source, dual-energy computed tomography using a split-filter (tbDECT) to a dual-source dual-energy CT (dsDECT).

Materials and Methods In this retrospective study, comparisons for tbDECT and dsDECT were made within and between different dual-energy platforms. For the interscanner comparison, 126 patients were scanned with both scanners within a time interval of 224 ± 180 days; for the intrascanner comparison, another 90 patients were scanned twice with the same scanner within a time interval of 136 ± 140 days. Virtual unenhanced images were processed off of venous phase series. Attenuation values of 7 different tissues were recorded. Disagreement for VUE HU measurements greater than 10 HU between 2 scans was defined as inadequate.

Results The interscanner analysis showed significant difference between tbDE and dsDE VUE CT values (P < 0.01) for 6 of 7 organs. Percentage of cases that had more than 10 HU difference between tbDE and dsDE for an individual patient ranged between 15% (left kidney) and 62% (spleen).

The intrascanner analysis showed no significant difference between repeat scans for both tbDECT and dsDECT (P > 0.05). However, intrascanner disagreements for the VUE HU measurements greater than 10 HU were recorded in 10% of patients scanned on the tbDECT and 0% of patients scanned on the dsDECT. The organs with the highest portion of greater than 10 HU errors were the liver and the aorta (both 20%).

Conclusions Dual-energy techniques vary in reproducibility of VUE attenuation values. In the current study, tbDECT demonstrated higher variation in VUE HU measurements in comparison to a dsDECT. Virtual unenhanced HU measurements cannot be reliably compared on follow-up CT, if these 2 different dual-energy CT platforms are used.

From the *Clinic of Radiology and Nuclear Medicine, University of Basel Hospital, University of Basel, Basel, Switzerland;

Department of Radiology and Biomedical Imaging, University of California San Francisco, San Francisco, CA; and

Radiology Institute University of Turin, Turin, Italy.

Received for publication April 3, 2018; and accepted for publication, after revision, June 5, 2018.

Conflicts of interest and sources of funding: none declared.

Markus M. Obmann and Vanessa Kelsch contributed equally.

Supplemental digital contents are available for this article. Direct URL citations appear in the printed text and are provided in the HTML and PDF versions of this article on the journal’s Web site (www.investigativeradiology.com).

Correspondence to: Matthias R. Benz, MD, Clinic of Radiology and Nuclear Medicine, University of Basel Hospital, University of Basel, Petersgraben 4, CH-4031 Basel, Switzerland. E-mail: Matthias.Benz@usb.ch.

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