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. 2019 Aug;98(33):e16606.
doi: 10.1097/MD.0000000000016606.

Computed tomography pulmonary angiograms using a novel dual-layer spectral detector: Adjusted window settings are essential for diagnostic image quality

Andra-Iza Iuga  1 , Jonas Doerner  1 , Florian Siedek  1 , Stefan Haneder  1 , Jonathan Byrtus  1 , Julian A Luetkens  2 , David Maintz  1 , Tilman Hickethier  1
Affiliations

Computed tomography pulmonary angiograms using a novel dual-layer spectral detector: Adjusted window settings are essential for diagnostic image quality

Andra-Iza Iuga et al. Medicine (Baltimore). 2019 Aug.

Abstract

Objective: The aim of this study was to determine optimal window settings for conventional polyenergetic and virtual monoenergetic images derived from computed tomography pulmonary angiogram (CTPA) examinations of a novel dual-layer spectral detector computed tomography system (DLCT).

Methods: Monoenergetic (40 keV) and polyenergetic images of 50 CTPA examinations were calculated and the best individual window width and level (W/L) values were manually assessed. Optimized values were obtained afterwards based on regression analysis. Diameters of standardized pulmonary artery segments and subjective image quality parameters were evaluated and compared.

Results: Attenuation and contrast-to-noise values were higher in monoenergetic than in polyenergetic images (P≤.001). Averaged best individual W/L for polyenergetic and monoenergetic were 1020/170 and 2070/480 HU, respectively.All adjusted W/L-settings varied significantly compared to standard settings (700/100 HU) and obtained higher subjective image quality scores. A systematic overestimation of artery diameters for standard window settings in monoenergetic images was observed.

Conclusions: Appropriate W/L-settings are required to assess polyenergetic and monoenergetic CTPA images of a novel DLCT. W/L-settings of 1020/170 HU and 2070/480 HU were found to be the best averaged values for polyenergetic and monoenergetic CTPA images, respectively.

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Conflict of interest statement

The authors report no conflicts of interest.

Figures

Figure 1
Figure 1
Complete image dataset showing PolyE and MonoE 40 keV images with the 4 different window settings for pulmonary artery assessment. Note the excessive overexposure if standard window settings were used for MonoE images, which led to an overestimation of vessel size. With adjusted window settings, artery assessability (particularly of the distal branches) was considerably improved. Ind.-W/L = individual width and level settings, MonoE = virtual monoenergetic imaging at 40 keV, PolyE = polyenergetic imaging, Std.-W/L = standard width and level settings.
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