Jungblut Lisa, Abel Frederik, Nakhostin Dominik, Mergen Viktor, Sartoretti Thomas, Euler André, Frauenfelder Thomas, Martini Katharina
Institute of Diagnostic and Interventional Radiology, University Hospital Zurich, University of Zurich, Raemistrasse 100 CH-8091 Zurich, Switzerland.
Institute of Diagnostic and Interventional Radiology, University Hospital Zurich, University of Zurich, Raemistrasse 100 CH-8091 Zurich, Switzerland.
Diagn Interv Imaging. 2023 Feb;104(2):84-90. doi: 10.1016/j.diii.2022.09.006. Epub 2022 Oct 8.
The purpose of this study was to evaluate the impact of virtual monoenergetic image (VMI) energies and iodine maps on the diagnosis of pleural empyema with photon counting detector computed tomography (PCD-CT).
In this IRB-approved retrospective study, consecutive patients with non-infectious pleural effusion or histopathology-proven empyema were included. PCD-CT examinations were performed on a dual-source PCD-CT in the multi-energy (QuantumPlus) mode at 120 kV with weight-adjusted intravenous contrast-agent. VMIs from 40-70 keV obtained in 10 keV intervals and an iodine map was reconstructed for each scan. CT attenuation was measured in the aorta, the pleura and the peripleural fat (between autochthonous dorsal muscles and dorsal ribs). Contrast-to-noise (CNR) and signal-to-noise (SNR) ratios were calculated. Two blinded radiologists evaluated if empyema was present (yes/no), and rated diagnostic confidence (1 to 4; not confident to fully confident, respectively) with and without using the iodine map. Sensitivity, specificity and diagnostic confidence were estimated. Interobserver agreement was estimated using an unweighted Cohen kappa test. A one-way ANOVA was used to compare variables. Differences in sensitivity and specificity between the different levels of energy were searched using McNemar test.
Sixty patients (median age, 60 years; 26 women) were included. A strong negative correlation was found between image noise and VMI energies (r = -0.98; P = 0.001) and CNR increased with lower VMI energies (r = -0.98; P = 0.002). Diagnostic accuracy (96%; 95% CI: 82-100) as well as diagnostic confidence (3.4 ± 0.75 [SD]) were highest at 40 keV. Diagnostic accuracy and confidence at higher VMI energies improved with the addition of iodine maps (P ≤0.001). Overall, no difference in CT attenuation of peripleural fat between patients with empyema and those with pleural effusion was found (P = 0.07).
Low VMI energies lead to a higher diagnostic accuracy and diagnostic confidence in the diagnosis of pleural empyema. Iodine maps help in diagnosing empyema only at high VMI energies.
本研究旨在评估虚拟单能图像（VMI）能量和碘图对光子计数探测器计算机断层扫描（PCD-CT）诊断胸腔积液的影响。
在这项经机构审查委员会批准的回顾性研究中，纳入了连续的非感染性胸腔积液患者或经组织病理学证实的胸腔积液患者。在双源PCD-CT上以120 kV的多能量（QuantumPlus）模式进行PCD-CT检查，并根据体重调整静脉注射造影剂。以10 keV的间隔获取40-70 keV的VMI，并为每次扫描重建碘图。在主动脉、胸膜和胸膜周围脂肪（在自体背肌和背肋之间）测量CT衰减。计算对比噪声比（CNR）和信噪比（SNR）。两名盲法放射科医生评估是否存在胸腔积液（是/否），并在使用和不使用碘图的情况下对诊断信心进行评分（1至4分；分别从不自信到完全自信）。估计敏感性、特异性和诊断信心。使用非加权Cohen kappa检验估计观察者间的一致性。使用单因素方差分析比较变量。使用McNemar检验搜索不同能量水平之间敏感性和特异性的差异。
纳入60例患者（中位年龄60岁；26例女性）。发现图像噪声与VMI能量之间存在强烈的负相关（r = -0.98；P = 0.001），且CNR随着较低的VMI能量而增加（r = -0.98；P = 0.002）。在40 keV时，诊断准确性（96%；95% CI：82-100）以及诊断信心（3.4±0.75[标准差]）最高。在较高的VMI能量下，添加碘图可提高诊断准确性和信心（P≤0.001）。总体而言，胸腔积液患者和胸腔积液患者之间胸膜周围脂肪的CT衰减没有差异（P = 0.07）。
低VMI能量在胸腔积液的诊断中具有更高的诊断准确性和诊断信心。碘图仅在高VMI能量下有助于诊断胸腔积液。
