Department of Radiology, University of Wisconsin-School of Medicine and Public Health, Madison, Wisconsin.
Department of Radiology, Charité University Hospital, Berlin, Germany.
Magn Reson Med. 2019 Nov;82(5):1660-1670. doi: 10.1002/mrm.27853. Epub 2019 Jun 22.
To evaluate the feasibility of ferumoxytol (FE)-enhanced UTE-MRA for depiction of the pulmonary vascular and nonvascular structures.
Twenty healthy volunteers underwent contrast-enhanced pulmonary MRA at 3 T during 2 visits, separated by at least 4 weeks. Visit 1: The MRA started with a conventional multiphase 3D T -weighted breath-held spoiled gradient-echo MRA before and after the injection of 0.1 mmol/kg gadobenate dimeglumine (GD). Subsequently, free-breathing GD-UTE-MRA was acquired as a series of 3 flip angles (FAs) (6°, 12°, 18°) to optimize T weighting. Visit 2: After the injection of 4 mg/kg FE, MRA was performed during the steady state, starting with a conventional 3D T -weighted breath-held spoiled gradient-echo MRA and followed by free-breathing FE-UTE-MRA, both at 4 different FAs (6°, 12°, 18°, 24°). The optimal FA for best T contrast was evaluated. Image quality at the optimal FA was compared between methods on a 4-point ordinal scale, using multiphase GD conventional pulmonary MRA (cMRA) as standard of reference.
Flip angle in the range of 18°-24° resulted in best T contrast for FE cMRA and both UTE-MRA techniques (p > .05). At optimized FA, image quality of the vasculature was good/excellent with both FE-UTE-MRA and GD cMRA (98% versus 97%; p = .51). Both UTE techniques provided superior depiction of nonvascular structures compared with either GD-enhanced or FE-enhanced cMRA (p < .001). However, GD-UTE-MRA showed the lowest image quality of the angiogram due to low image contrast.
Free-breathing UTE-MRA using FE is feasible for simultaneous assessment of the pulmonary vasculature and nonvascular structures. Patient studies should investigate the clinical utility of free-breathing UTE-MRA for assessment of pulmonary emboli.
评估使用超顺磁性氧化铁（FE）增强的 UTE-MRA 显示肺血管和非血管结构的可行性。
20 名健康志愿者在 3T 下分两次进行对比增强肺部 MRA 检查，两次检查间隔至少 4 周。第一次检查：MRA 首先进行常规多相位 3D T1 加权呼吸暂停扰相梯度回波 MRA，然后在注射 0.1mmol/kg 钆贝葡胺（GD）前后进行。随后，进行自由呼吸 GD-UTE-MRA 采集，采用 3 种翻转角（FA）（6°、12°、18°）优化 T 加权。第二次检查：注射 4mg/kg FE 后，在稳态下进行 MRA，首先进行常规 3D T1 加权呼吸暂停扰相梯度回波 MRA，然后进行自由呼吸 FE-UTE-MRA，均在 4 种不同的 FA（6°、12°、18°、24°）下进行。评估最佳 T 对比的最佳 FA。使用多相位 GD 常规肺部 MRA（cMRA）作为参考标准，在 4 分等级量表上比较两种方法在最佳 FA 下的图像质量。
FE cMRA 和两种 UTE-MRA 技术的最佳 FA 范围为 18°-24°，T 对比度最佳（p >.05）。在优化的 FA 下，FE-UTE-MRA 和 GD cMRA 的血管图像质量均为良好/优秀（98%与 97%；p =.51）。与 GD 增强或 FE 增强的 cMRA 相比，两种 UTE 技术均能更好地显示非血管结构（p <.001）。然而，由于图像对比度低，GD-UTE-MRA 显示的血管造影图像质量最低。
使用 FE 进行自由呼吸 UTE-MRA 是可行的，可同时评估肺血管和非血管结构。患者研究应调查自由呼吸 UTE-MRA 在评估肺栓塞中的临床应用价值。
