Theory and Practice of MRA-Guided Transcranial Doppler Sonography

Despite consisting of 2 – 3% of total body mass, the brain accounts for ~20% of the body’s oxygen consumption and therefore must receive significant blood supply to maintain homeostasis (Ainslie & Duffin, 2009). This profound dependency on blood supply belies the brain’s apparent ability to regulate blood supply so tightly. Hence, the brain’s ability to regulate its blood supply has been, and still is, the subject of considerable research (e.g., Kety & Schmidt, 1948; Panerai et al., 2009; Willie & Smith, 2011; Willie et al., 2011; also see Ainslie & Duffin, 2009 for a recent review). However, the dense cortical bone of the skull does not lend itself easily to normal ultrasound techniques.