OBJECTIVE To demonstrate the value of optimizing non-contrast head imaging tasks by using the multiple virtual monochromatic spectral imaging (VMSI) sets in dual-energy spectral computed tomography (CT) and determine the optimal energy levels for various tasks in imaging head. MATERIALS AND METHODS This retrospective study includes 55 patients (29 women and 26 men, average age of 54.5±12.3years) who underwent non-contrast head CT in spectral imaging mode. For each patient, 21 VMSI sets from 40 to 140 keV at 5 keV intervals and 120 kVp-like image were reconstructed. Signal-to-noise ratio (SNR) for gray matter (GM) and white matter (WM), contrast-to-noise ratio (CNR) between GM and WM, subcalvarial artifact index (SAI) and posterior fossa artifact index (PFAI) were measured by placing regions-of-interest (ROIs) in nine areas of the brain. Two radiologists subjectively rated the image quality in terms of GM-WM differentiation, beam hardening artifacts in the subcalvarial space, and posterior fossa. The overall image noise was evaluated using a 5-point Likert scale. Measurement data were then statistically analyzed. RESULTS The optimal energy level for viewing the supratentorial brain and reducing beam hardening artifacts in the subcalvarial space and posterior fossa was 65 keV and 75 keV, respectively. All corresponding measurements at these energy levels were significantly better than those measured at other energy levels (all P < 0.05). CONCLUSIONS Dual-energy spectral CT imaging provides a set of virtual monochromatic spectral imaging and can be selected on-demand to optimize the imaging tasks in non-contrast head CT. VMSI reconstruction of dual-energy unenhanced head CT scans at 65-75 keV enables to maximize image quality.

中文翻译：

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使用双能谱CT中的多个虚拟单色图像集优化无对比头CT成像任务。

目的通过在双能谱计算机断层扫描（CT）中使用多个虚拟单色光谱成像（VMSI）集来证明优化非对比头成像任务的价值，并确定成像头中各种任务的最佳能量水平。材料与方法这项回顾性研究包括55例以频谱成像模式进行非对比头CT的患者（29例女性和26例男性，平均年龄54.5±12.3岁）。对于每位患者，以5 keV间隔从40到140 keV设置21个VMSI集，并重建了120 kVp样的图像。灰质（GM）和白质（WM）的信噪比（SNR），GM和WM之间的对比度-噪声比（CNR），颅底伪影指数（SAI）和后颅窝伪影指数（PFAI）通过将感兴趣区域（ROI）放置在大脑的九个区域来进行测量。两名放射科医生根据GM-WM的差异，颅下腔内的束硬化伪像和后颅窝对图像质量进行了主观评估。使用5点李克特量表评估整体图像噪声。然后对测量数据进行统计分析。结果观察颅上大脑和减少颅下间隙和后颅窝的束硬化伪影的最佳能量水平分别为65 keV和75 keV。在这些能级下的所有相应测量值均显着优于在其他能级下进行的测量（所有P <0.05）。结论双能谱CT成像提供了一组虚拟的单色谱成像，可以按需选择以优化非对比头CT的成像任务。