Quantitative Biomedical Imaging Laboratory

Title: Organ-specific effects of oxygen and carbogen gas inhalation on tissue longitudinal relaxation times
Authors: J.P.B. O’Connor, A. Jackson, G.A. Buonaccorsi, Y. Watson, S. Cheung, C. Roberts, D.M. McGrath, J.H Naish, C. Rose, P.M. Dark, G.C. Jayson, D.L. Buckley, G.J.M. Parker
Journal: Magn. Reson. Med.
Link: http://www3.interscience.wiley.com/cgi-bin/jhome/10005196
Year: 2007
Volume: 58
Number: 3
Pages: 490–496
Month: September
Abstract: Molecular oxygen is known to shorten longitudinal relaxation time (T1) in the spleen and renal cortex, but not in the liver. In this study, we investigated the magnitude and temporal evolution of this effect in abdominal organs. Medical air, oxygen and carbogen (95% oxygen/5% CO2 mix) were administered sequentially in 16 healthy volunteers. T1 maps were produced every 76.8 s using fast field echo sequences (TR 3.5 ms, TE 0.9 ms, θ = 2°/ 8°/ 17°) with 6 acquisitions on air, 12 on oxygen, 12 on carbogen and 6-12 back on air. Mean T1 values and change in relaxation rate were compared between gases 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 were greater than previously reported (both p<0.001). Carbogen induced conflicting responses in different organs suggesting a complex relationship with organ vasculature. The T1-shortening effect of oxygen in abdominal tissues is more pronounced and more complex than previously recognised. It may be useful as a biomarker of arterial flow and oxygen delivery to vascular beds.