O'Connor James P B, Jackson Alan, Buonaccorsi Giovanni A, Buckley David L, Roberts Caleb, Watson Yvonne, Cheung Sue, McGrath Deirdre M, Naish Josephine H, Rose Chris J, Dark Paul M, Jayson Gordon C, Parker Geoff J M
Imaging Science and Biomedical Engineering, University of Manchester, and Cancer Research UK Department of Medical Oncology, Christie Hospital, Manchester, UK. james.o'
Magn Reson Med. 2007 Sep;58(3):490-6. doi: 10.1002/mrm.21357.
Molecular oxygen has been previously shown to shorten longitudinal relaxation time (T1) in the spleen and renal cortex, but not in the liver or fat. In this study, the magnitude and temporal evolution of this effect were investigated. Medical air, oxygen, and carbogen (95% oxygen/5% CO2) were administered sequentially in 16 healthy volunteers. T1 maps were acquired using spoiled gradient echo sequences (TR=3.5 ms, TE=0.9 ms, alpha=2 degrees/8 degrees/17 degrees) with six acquisitions on air, 12 on oxygen, 12 on carbogen, and six to 12 back on air. Mean T1 values and change in relaxation rate were compared between each phase of gas inhalation in the liver, spleen, skeletal muscle, renal cortex, and fat by one-way analysis of variance. Oxygen-induced T1-shortening occurred in the liver in fasted subjects (P<0.001) but not in non-fasted subjects (P=0.244). T1-shortening in spleen and renal cortex (both P<0.001) were greater than previously reported. Carbogen induced conflicting responses in different organs, suggesting a complex relationship with organ vasculature. Shortening of tissue T1 by oxygen is more pronounced and more complex than previously recognized. The effect may be useful as a biomarker of arterial flow and oxygen delivery to vascular beds.
先前已表明，分子氧可缩短脾脏和肾皮质的纵向弛豫时间（T1），但对肝脏或脂肪则无此作用。在本研究中，对这种效应的大小和时间演变进行了调查。对16名健康志愿者依次给予医用空气、氧气和混合气（95%氧气/5%二氧化碳）。使用扰相梯度回波序列（TR = 3.5毫秒，TE = 0.9毫秒，α = 2度/8度/17度）采集T1图谱，在吸入空气时采集6次，吸入氧气时采集12次，吸入混合气时采集12次，然后再吸入空气时采集6至12次。通过单因素方差分析比较肝脏、脾脏、骨骼肌、肾皮质和脂肪在每个气体吸入阶段的平均T1值和弛豫率变化。禁食受试者的肝脏中出现了氧气诱导的T1缩短（P < 0.001），而非禁食受试者则未出现（P = 0.244）。脾脏和肾皮质的T1缩短（均为P < 0.001）比先前报道的更为明显。混合气在不同器官中引起了相互矛盾的反应，表明其与器官血管系统存在复杂关系。氧气对组织T1的缩短比先前认识到的更为显著和复杂。这种效应可能作为动脉血流和向血管床输送氧气的生物标志物。
