Virtual monochromatic spectral imaging versus linearly blended dual-energy and single-energy imaging during CT-guided biopsy needle positioning: Optimization of keV settings and impact on image quality

Abstract

ObjectivesTo compare image quality and metal artifact reduction between virtual monochromatic spectral imaging (VMSI), linearly blended dual-energy (DE) and single-energy (SE) images, each with and without dedicated iterative metal artifact reduction (iMAR) for CT-guided biopsy. Materials and methodsA biopsy trocar was positioned in the liver of six pigs. DE (Sn140/100kV p ) and SE (120kV p / 200mAs) acquisitions were performed with equivalent dose. From dual-energy datasets DE Q30-3 images and VMSI between 40-180 keV in steps of 20 keV were generated. From SE datasets I30-3 images were reconstructed. All images were reconstructed with and without iMAR. Objective image quality was analyzed applying density measurements at standardized positions (e.g. trocar tip and liver parenchyma adjacent to the trocar tip) and semi-automated threshold based segmentation. Subjective image quality was performed using semiquantitative scores. Analyses were performed by two observers. ResultsAt the trocar tip quantitative image analysis revealed significant difference in CT numbers between reconstructions with iMAR compared to reconstructions without iMAR for VMSI at lower keV levels (80 and 100 keV; p = 0.03) and DE (p = 0.03). For liver parenchyma CT numbers were significantly higher in VMSI at high keV compared to low keV (p�0.01). VMSI at high keV also showed higher CT numbers compared to DE and SE images, though not the level of statistical significance. The best signal-to-noise ratio for VMSI was at 80 keV and PLOS ONE | https://doi.org/10.1371/journal.pone.0228578 February 10, 2020 1 / 17 OPEN ACCESS Citation: Do TD, Heim J, Melzig C, Vollherbst DF, Kauczor HU, Skornitzke S, et al. (2020) Virtual monochromatic spectral imaging versus linearly blended dual-energy and single-energy imaging during CT-guided biopsy needle positioning: Optimization of keV settings and impact on image quality. PLoS ONE 15(2): e0228578. https://doi.org/10.comparable to DE and SE. Noise was lowest at 80 keV and lower than in DE and SE. Subjective image quality was best with VMSI at 80 keV regardless of the application of iMAR. iMAR significantly improved image quality at levels of 140 keV and 160 keV. Interreaderagreement was good for quantitative and qualitative analysis. Conclusion iMAR improved image quality in all settings. VMSI with iMAR provided metal artifact reduction and better image quality at 80 keV and thus could improve the accurate positioning in CT-guided needle biopsy. In comparison, DE imaging did not improve image quality compared to SE. VMSI during CT-guided Needle Positioning PLOS ONE | https://doi.

Utility of Dual-Energy CT in Abdominal Interventions

“…VMSI at 80 keV is usually recommended. Iterative metal artifact reduction can be deployed to mitigate metal artifacts independently of acquisition and reconstruction algorithms 38 ( Fig. 7 ).…”

“…Motion and beam hardening artifacts may degrade image quality in most dual-energy current CT systems available currently and must be reduced. 38 Suboptimal bone removal requires improvement. The major workflow constraints, such as increased reconstruction time, increased volume of images, and increased interpretation time, significantly increase the workload and hinder the use of DECT imaging in routine intervention radiology practice.…”