Krinsky G A, Kaminer E, Lee V S, Rofsky N M, Weinreb J C
Department of Radiology-MRI, NYU Medical Center 10016, USA.
J Comput Assist Tomogr. 1998 Sep-Oct;22(5):677-81. doi: 10.1097/00004728-199809000-00001.
Our purpose was to determine the effects of apnea during end-inspiration compared with free breathing on timing examinations performed to optimize gadolinium-enhanced 3D MR angiography (MRA) of the thoracic aorta and arch vessels.
Thirty patients referred for gadolinium-enhanced 3D MRA of the thoracic aorta and branch vessels underwent two timing examinations: one performed during free breathing and one during apnea at end-inspiration to replicate more closely the respiratory pattern used to obtain 3D MRA. For each, axial images at the level of the proximal neck were acquired every 2 s for 40 s, during which time 1 ml of gadolinium contrast agent followed by 20 ml of saline was infused at 2 ml/s. The time to peak arterial enhancement (Ta), time to first jugular venous enhancement (Tj), and arterio-venous window (time from peak arterial enhancement to first jugular venous enhancement; AV) were compared for the two examinations in each patient.
Overall there was no statistically significant difference in Ta, Tj, or AV between examinations performed during free breathing and apnea in end-inspiration, although a trend to delayed circulation times was observed with apnea (p = 0.2-0.3). In five patients (17%), the difference in Ta between free breathing and apnea was 4 s; in three patients (10%), the difference was 6 s.
Circulation times determined during apnea at end-inspiration may differ from those obtained during free breathing by as much as 6 s in an individual patient. This difference may account for inappropriately timed gadolinium-enhanced MR angiograms performed with timing examinations, especially when very short acquisition times and low doses of gadolinium (20 ml) are used.
我们的目的是确定吸气末屏气与自由呼吸相比，对为优化钆增强三维磁共振血管造影（MRA）检查胸主动脉和主动脉弓血管的时间测定的影响。
30例因钆增强三维MRA检查胸主动脉和分支血管而就诊的患者接受了两次时间测定检查：一次在自由呼吸时进行，另一次在吸气末屏气时进行，以更紧密地复制用于获取三维MRA的呼吸模式。每次检查时，在近端颈部水平每2秒采集一次轴向图像，共采集40秒，在此期间，以2ml/s的速度注入1ml钆造影剂，随后注入20ml生理盐水。比较每位患者两次检查的动脉强化峰值时间（Ta）、颈静脉首次强化时间（Tj）和动静脉窗（从动脉强化峰值到颈静脉首次强化的时间；AV）。
总体而言，自由呼吸时和吸气末屏气时进行的检查之间，Ta、Tj或AV在统计学上没有显著差异，尽管屏气时观察到循环时间有延迟趋势（p = 0.2 - 0.3）。在5例患者（17%）中，自由呼吸和屏气时Ta的差异为4秒；在3例患者（10%）中，差异为6秒。
吸气末屏气时测定的循环时间与自由呼吸时获得的循环时间在个体患者中可能相差多达6秒。这种差异可能导致在时间测定检查中钆增强磁共振血管造影的时间不合适，特别是当使用非常短的采集时间和低剂量钆（20ml）时。
