Sarah C Wayte1, Victoria Sherwood1, Ravjit Sagoo1, Eddie Ng'andwe1, Charles E Hutchinson1,2, and Christopher HE Imray1,2
The apparent changes in venous calibre on susceptibility
weighted imaging (SWI) of six normal volunteers pre-hypoxia, during the first 12
minutes of hypoxia, and at 30 and 60 minutes were investigated.
For all subjects there was a step increase in apparent
venous calibre on SWI which occurred within the first few minutes of hypoxia,
and this was maintained up to 60 minutes.
The apparent increase in venous calibre occurred too
rapidly after hypoxia induction to be entirely due to an increase in vessel
volume. The vessels appear dilated because of the greater magnetic
susceptibility of deoxyhaemoglobin than oxyhaemoglobin.