头颅损伤CT片阅读技巧..docx

How to read a head CTThe mnemonic used by Dr. Andrew Perron who lectures on this topic frequently is: Blood Can Be Very Bad. Content and images below are taken from his lecture (with his permission).This stands forB - bloodC - cisternsB - brainV - ventriclesB - bonesStep: 1 bloodLook for any evidence of bleeding throughout all slices of the head CT.Blood will appear bright white and is typically in the range of 50-100 Houndsfield units.Basic categories of blood in the brain are epidural, subdural, intraparenchymal/intracerebral, intraventricular, and subarachnoid.Epidural (lens shaped, does not cross suture lines)Subdural (crescent shaped, does cross suture lines)Intraparenchymal /intracerbral hemorrhage (high density bleeds most often in the basal ganglia area if due to HTN)Intraventricular hemorrhageSubarachnoid hemorrhage (due most often to aneurysms, CT sensitivity decreases sharply with time)Step: 2 cisterns2 Key questions to answer regarding the 4 key cisterns (Circummesencephalic, Suprasellar, Quadrigeminal and Sylvian)- Is there blood?-Are the cisterns open?Circummesencephalic cisternSuprasellar cisternQuadrigeminal cisternSylvian cisternStep: 3 brainExamine the brain forSymmetry - make sure sulci and gyri appear the same on both sides. (easiest when patient not rotated in the scanner)Grey-white differentiation - the earliest sign of a CVA on CT scan is the loss of the grey-white interface on CT scan. Compare side to side.Shift - the falx should be in the midline with ventricles the same on both sides. Check for effacement of sulci (unilateral or bilateral).Hyper/hypodenisty - blood, calcification and IV contrast are hyperdense (appear lighter) and air, fat and areas of tumor ischemia are hypodense (appear darker).Step: 4 ventriclesExamine for IIIrd, IVth and lateral ventricles for dilation or compression/shift.Pathologic processes cause dilation (hydrocephalus) or compression/shift. Communicating vs. Non-communicating. Communicating hydrocephalus is first e