Department of Radiology and Medical Imaging, University of Virginia Health System, 1215 Lee St, Box 800170, Charlottesville, VA 22908, USA.
AJR Am J Roentgenol. 2013 Feb;200(2):451-60. doi: 10.2214/AJR.11.8033.
The objective of our study was to evaluate the diagnostic performance of dual-source dual-energy CT (DECT) in the detection of endoleaks after thoracic endovascular aortic repair for thoracic aortic aneurysm and to investigate if a double-phase (arterial and dual-energy late delayed phase) or a single-phase (dual-energy late delayed phase) acquisition can replace the standard triphasic protocol.
All DECT examinations performed for evaluation after thoracic endovascular aortic repair during a 30-month period were retrospectively reviewed. An initial single-source unenhanced acquisition was followed by a single-source arterial phase acquisition and a dual-energy 300-second late delayed phase acquisition. "Virtual noncontrast images" were generated from the dual-energy acquisition. Two independent and blinded radiologists evaluated the cases during three reading sessions: session A (triphasic protocol: standard unenhanced, arterial phase, and late delayed phase), session B (virtual noncontrast and late delayed phase), and session C (virtual noncontrast, arterial phase, and late delayed phase). The diagnostic accuracies of sessions B and C were calculated using session A as the reference standard. Contrast-to-noise ratios and effective radiation doses were calculated.
Forty-eight patients (mean age, 66 years; age range, 19-84 years) underwent 74 triple-phase CT examinations. The single-phase studies (session B) were characterized by 85.7% sensitivity, 100% specificity, 100% negative predictive value (NPV), and 94.6% positive predictive value (PPV). The dual-phase study (session C) revealed 100% sensitivity, 100% specificity, 100% NPV, and 100% PPV. The use of the dual-phase protocol and single-phase protocol resulted in a radiation exposure reduction of 19.5% and 64.1%, respectively.
Virtual noncontrast and late delayed phase images reconstructed from a single DECT acquisition can replace the standard triphasic protocol in follow-up examinations after thoracic endovascular aortic repair, thereby providing a significant dose reduction.
本研究旨在评估双源双能 CT（DECT）在检测胸主动脉瘤腔内修复术后内漏中的诊断性能，并探讨双期（动脉期和双能延迟晚期）或单期（双能延迟晚期）采集是否可以替代标准三期方案。
回顾性分析了 30 个月期间因评估而进行的所有 DECT 检查。首先进行单源平扫采集，然后进行单源动脉期采集和双能 300 秒延迟晚期采集。从双能采集生成“虚拟非增强图像”。两位独立的、盲法的放射科医生在三个阅读阶段评估病例：阶段 A（三期方案：标准平扫、动脉期和延迟晚期）、阶段 B（虚拟非增强和延迟晚期）和阶段 C（虚拟非增强、动脉期和延迟晚期）。使用阶段 A 作为参考标准计算阶段 B 和 C 的诊断准确性。计算了对比噪声比和有效辐射剂量。
48 例患者（平均年龄 66 岁；年龄范围 19-84 岁）进行了 74 次三期 CT 检查。单期研究（阶段 B）的特征是敏感性 85.7%、特异性 100%、阴性预测值（NPV）100%和阳性预测值（PPV）94.6%。双期研究（阶段 C）显示敏感性 100%、特异性 100%、NPV 100%和 PPV 100%。使用双期方案和单期方案可使辐射暴露分别减少 19.5%和 64.1%。
从单次 DECT 采集重建的虚拟非增强和延迟晚期图像可以替代胸主动脉瘤腔内修复术后的标准三期方案，从而显著降低剂量。
