A Patient with a Head Injury Has an Intracranial Pressure

A patient with a head injury has an intracranial pressure (ICP) of 18 mm Hg.The blood pressure is 144/90 mm Hg,and mean arterial pressure (MAP) is 108 mm Hg.What is the cerebral perfusion pressure (CPP) ?

A) 54 mm Hg
B) 72 mm Hg
C) 90 mm Hg
D) 126 mm Hg