Basic Imaging of the Nervous System Flashcards
When would a skull x-ray be performed?
Largely obsolete unless there is a penetrating injury
What are the advantages of CT scans?
Excellent bone detail, good for blood/calcium, quiet and spacious machine, vascularity and perfusion can be seen in 3D and can be used to guide biopsy
What are the disadvantages of CT scans?
Limited soft tissue details, high radiation dose (x-rays) and limited soft tissue resolution
What is the difference between a T1 weighted sagittal and a T2 weighted axial MRI scan?
T2 is sensitive to pathology e.g. tumours, inflammation, infection and ischaemia, whereas T1 provides better anatomical image but is less sensitive to pathology
What are the advantages of MRI?
Excellent characterisation of lesions, imaging in any plane (axial, coronal or sagittal) and there’s no radiation involved
What are the disadvantages of MRI?
Prolonged scanning time, strong magnetic field and very expensive
What is an axial plane?
A cross section
Horizontal = relative to ground so depends on patient’s position
Transverse = relative to the body
What is a sagittal plane?
Separates the two sides of the body, left and right
What is a coronal plane?
Separates the anterior from the posterior body
On CT scans what does a very black region indicate?
Air
On CT scans what does a black region indicate?
Fat
On CT scans what does a dark grey region indicate?
Water
On CT scans what does a grey region indicate?
Brain
On CT scans what does a white region indicate?
Blood or iodine contrast
On CT scans what does a very white region indicate?
Bone
