Hofmann Nina P, Schuetz Moritz, Bekeredjian Raffi, Pleger Sven, Chorianopoulos Emanuel, Giusca Sorin, André Florian, Gitsioudis Gitsios, Schlett Christopher, Kauczor Hans-Ulrich, Katus Hugo A, Korosoglou Grigorios
Department of Cardiology, University of Heidelberg, Heidelberg, Germany.
Department of Radiology, University of Heidelberg, Heidelberg, Germany.
Eur J Radiol Open. 2017 Jun 26;4:75-83. doi: 10.1016/j.ejro.2017.06.001. eCollection 2017.
ECG-gated cardiac computed tomography angiography (CCTA) has found widespread use for prosthesis sizing before transcatheter aortic valve implantation (TAVI). However, still little data exists on the optimal scan-strategy in such patients. We hypothesized that prospectively triggered CCTA can enable the visualization of aortic valve structures and peripheral arteries with lower radiation and contrast agent exposure in patients considered for TAVI compared to retrospectively gated protocols.
All studies were performed using a 256 multi-detector single source CT (iCT Philips, Best, Netherlands). With the prospective protocol the whole volume from the heart to the iliofemoral arteries scanned using prospective triggering. With the retrospective protocol a first retrospectively gated scan was performed for the heart and the iliofemoral part was subsequently scanned using a second non-triggered scan. Image quality was assessed semi-quantitatively and signal-to-noise- (SNR) and contrast-to-noise-ratios (CNR) were obtained for all scans.
Prospective CCTA was performed in 74 and in 34 patients, respectively using non-tailored and BMI adapted scans, whereas retrospective CCTA was performed in 57 patients. Prospective scans required lower contrast agent administration compared to retrospective scans (71 ± 8 mL versus 91 ± 15 mL, p < 0.01) and resulted in lower radiation exposure (26 ± 7mSv for retrospective versus 15 ± 3mSv for non-tailored prospective versus 8 ± 4mSv for BMI-adapted prospective scans, p < 0.01). Visual image quality was better for the evaluation of aortic valve structures and similar for the assessment of iliofemoral anatomy with prospective versus retrospective scans. In addition, contrast density, SNR and CNR were higher in the ascending aorta with prospective versus retrospective CCTA (434 ± 98HU versus 349 ± 112HU; 35 ± 14 versus 24 ± 9 and 31 ± 11 versus 16 ± 7, p < 0.001 for all). Subsection analysis by heart rate groups demonstrated that both image quality and CNR were significantly higher in patients with prospective versus retrospective CCTA, irrespective of the heart rate during image acquisition.
Prospectively triggered CCTA allows for improved visualization of aortic valve structures and peripheral arteries in patients scheduled for TAVI with simultaneously reduced contrast agent dose and radiation exposure. Therefore, this acquisition mode seems to be the preferred for the evaluation of patients considered for TAVI.
心电图门控心脏计算机断层扫描血管造影（CCTA）在经导管主动脉瓣植入术（TAVI）前用于假体尺寸测量方面已得到广泛应用。然而，关于此类患者的最佳扫描策略的数据仍然很少。我们假设，与回顾性门控方案相比，前瞻性触发的CCTA能够在接受TAVI治疗的患者中以更低的辐射和造影剂暴露量实现主动脉瓣结构和外周动脉的可视化。
所有研究均使用256排多探测器单源CT（荷兰贝斯特的飞利浦iCT）进行。采用前瞻性方案时，使用前瞻性触发扫描从心脏到髂股动脉的整个容积。采用回顾性方案时，首先对心脏进行回顾性门控扫描，随后使用第二次非触发扫描对髂股部分进行扫描。对图像质量进行半定量评估，并获得所有扫描的信噪比（SNR）和对比噪声比（CNR）。
分别对74例和34例患者进行了前瞻性CCTA，采用了非定制扫描和根据体重指数（BMI）调整的扫描，而对57例患者进行了回顾性CCTA。与回顾性扫描相比，前瞻性扫描所需的造影剂用量更低（71±8 mL对91±15 mL，p<0.01），且辐射暴露更低（回顾性扫描为26±7 mSv，非定制前瞻性扫描为15±3 mSv，BMI调整的前瞻性扫描为8±4 mSv，p<0.01）。在前瞻性扫描与回顾性扫描中，主动脉瓣结构评估的视觉图像质量更好，髂股解剖结构评估的视觉图像质量相似。此外，与回顾性CCTA相比，前瞻性CCTA时升主动脉的对比剂密度、SNR和CNR更高（434±98 HU对349±112 HU；35±14对24±9，31±11对16±7，所有p<0.001）。按心率分组进行的亚组分析表明，无论图像采集时的心率如何，前瞻性CCTA患者的图像质量和CNR均显著高于回顾性CCTA患者。
前瞻性触发的CCTA能够在接受TAVI治疗的患者中更好地实现主动脉瓣结构和外周动脉的可视化，同时降低造影剂剂量和辐射暴露。因此，这种采集模式似乎是评估考虑接受TAVI治疗患者的首选。
