Detailed Instructions: In this task, you will be given sentences in which your task is to recognize the name of the organ of the body. An organ is a collection of tissues that structurally form a functional unit specialized to perform a particular function. Although there might be several correct answers, you need to write one of them.
Q:  Intra - operative monitoring of partial pressure of tissue oxygen ( PtiO2 ) is a very sensitive method of detecting the decrease of oxygen for cell utilization , due to decreased blood flow , during temporary clipping and after definitive clipping , in middle cerebral artery incidental unruptured aneurysm surgery .
A:
cerebral