Radiology and Imaging Sciences, Clinical Center, National Institutes of Health, Bethesda, MD, USA.
Siemens Medical Solutions USA, Malvern, PA, USA.
Clin Imaging. 2023 Oct;102:109-115. doi: 10.1016/j.clinimag.2023.08.004. Epub 2023 Aug 23.
Advantages of virtual monoenergetic images (VMI) have been reported for dual energy CT of the head and neck, and more recently VMIs derived from photon-counting (PCCT) angiography of the head and neck. We report image quality metrics of VMI in a PCCT angiography dataset, expanding the anatomical regions evaluated and extending observer-based qualitative methods further than previously reported.
In a prospective study, asymptomatic subjects underwent contrast enhanced PCCT of the head and neck using an investigational scanner. Image sets of low, high, and full spectrum (Threshold-1) energies; linear mix of low and high energies (Mix); and 23 VMIs (40-150 keV, 5 keV increments) were generated. In 8 anatomical locations, SNR and radiologists' preferences for VMI energy levels were measured using a forced-choice rank method (4 observers) and ratings of image quality using visual grading characteristic (VGC) analysis (2 observers) comparing VMI to Mix and Threshold-1 images.
Fifteen subjects were included (7 men, 8 women, mean 57 years, range 46-75). Among all VMIs, SNRs varied by anatomic location. The highest SNRs were observed in VMIs. Radiologists preferred 50-60 keV VMIs for vascular structures and 75-85 keV for all other structures. Cumulative ratings of image quality averaged across all locations were higher for VMIs with areas under the curve of VMI vs Mix and VMI vs Threshold-1 of 0.67 and 0.68 for the first reader and 0.72 and 0.76 for the second, respectively.
Preferred keV level and quality ratings of VMI compared to mixed and Threshold-1 images varied by anatomical location.
已经报道了虚拟单能量图像（VMI）在头部和颈部双能 CT 中的优势，最近还报道了头部和颈部光子计数（PCCT）血管造影衍生的 VMI。我们报告了 PCCT 血管造影数据集的 VMI 图像质量指标，扩展了评估的解剖区域，并进一步扩展了观察者定性方法，超出了之前的报道。
在一项前瞻性研究中，无症状受试者使用研究用扫描仪进行了对比增强的头部和颈部 PCCT。生成了低、高和全谱（阈值-1）能量的图像集、低和高能量的线性混合（Mix）以及 23 个 VMI（40-150keV，5keV 递增）。在 8 个解剖部位，使用强制选择等级方法（4 名观察者）测量 SNR 和放射科医生对 VMI 能量水平的偏好，以及使用视觉分级特征（VGC）分析（2 名观察者）比较 VMI 与 Mix 和 Threshold-1 图像的图像质量评分。
共纳入 15 名受试者（7 名男性，8 名女性，平均年龄 57 岁，范围 46-75 岁）。在所有 VMI 中，SNR 随解剖部位而异。最高的 SNR 出现在 VMI 中。放射科医生更喜欢血管结构的 50-60keV VMI 和所有其他结构的 75-85keV VMI。所有部位的平均图像质量累积评分均高于 VMI 与 Mix 和 VMI 与 Threshold-1 的曲线下面积分别为 0.67 和 0.68 的第一读者，以及分别为 0.72 和 0.76 的第二读者。
与混合和阈值-1 图像相比，VMI 的首选 keV 水平和质量评分因解剖部位而异。
