Department of Radiology, Kanazawa University Graduate School of Medical Sciences, Kanazawa, Japan.
Department of Diagnostic Imaging, The Cancer Institute Hospital of JFCR, Tokyo, Japan.
Acta Radiol. 2021 Aug;62(8):1122-1128. doi: 10.1177/0284185120950112. Epub 2020 Aug 16.
Inferior vena cava flow (IVCF) and abdominal aortic flow (AAF) are essential components of the systemic circulation. Although postural changes might alter IVCF and AAF by the gravity effect, the exact details are unknown.
To evaluate the effect of gravity on IVCF and AAF using a novel magnetic resonance imaging (MRI) system that can image in any position.
Caval velocity-mapped images were obtained using the cine phase-contrast technique in the upright and supine positions with multi-posture MRI (n = 12). The mean IVCF/AAF velocity, maximum IVCF/AAF velocity, cross-sectional area of IVC/AA, mean IVCF/AAF, maximum IVCF/AAF, and heart rate in the two positions were assessed.
The mean IVCF velocity, maximum IVCF velocity, cross-sectional area of IVC, mean IVCF, maximum IVCF, mean AAF velocity, maximum AAF velocity, mean AAF, and maximum AAF were significantly lower in the upright position compared with the supine position ( < 0.05 for all), with differences of 52% ± 33%, 36% ± 19%, 56% ± 18%, 26% ± 18%, 19% ± 11%, 33% ± 13%, 33% ± 22%, 42% ± 21%, and 37% ± 28%, respectively. Heart rate was significantly higher in the upright position compared with the supine position (116% ± 9.2%; = 0.003). There were no differences in cross-sectional area of AA between the two positions (108% ± 22%; = 0.583).
The effect of gravity decreases IVCF and AAF. Clarifying the effect of gravity on IVCF and AAF during a postural change may help to improve the management of patients with circulatory disease.
下腔静脉血流（IVCF）和腹主动脉血流（AAF）是全身循环的重要组成部分。尽管体位变化可能会通过重力效应改变 IVCF 和 AAF，但具体细节尚不清楚。
使用一种新型磁共振成像（MRI）系统评估重力对 IVCF 和 AAF 的影响，该系统可以在任何体位进行成像。
使用电影相位对比技术在直立和仰卧位获取腔静脉速度映射图像，采用多体位 MRI（n=12）。评估两种体位下的 IVCF/AAF 平均速度、最大 IVCF/AAF 速度、IVC/AA 横截面积、IVCF 平均速度、最大 IVCF 速度、AAF 平均速度、最大 AAF 速度、IVCF 平均速度、最大 IVCF 速度、AAF 平均速度和最大 AAF。
与仰卧位相比，直立位 IVCF 平均速度、最大 IVCF 速度、IVC 横截面积、IVCF 平均速度、最大 IVCF 速度、AAF 平均速度、最大 AAF 速度、AAF 平均速度、最大 AAF 速度分别显著降低（所有 < 0.05），差异分别为 52%±33%、36%±19%、56%±18%、26%±18%、19%±11%、33%±13%、33%±22%、42%±21%和 37%±28%。与仰卧位相比，直立位的心率显著升高（116%±9.2%； = 0.003）。两种体位的 AA 横截面积无差异（108%±22%； = 0.583）。
重力的作用会降低 IVCF 和 AAF。明确体位变化时重力对 IVCF 和 AAF 的影响，可能有助于改善循环系统疾病患者的管理。
