Lecture 1: MRI and CT info Flashcards
What density of bone loss can be detect on MRI?
Can pick up osteopoenic bone or bone demineralisation from 1-5%.
What density of bone loss can be detect on CT?
Can pick up osteopoenic bone or bone demineralisation from 10-20%.
What density of bone loss can be detected on X-ray?
30% +
What is highlighted in a T1 MRI?
Fat is the brightest
(gives best anatomical definition)
What is highlighted in a T2 MRI?
Water is the brightest (some fat areas have high water content so will show up brightly too)
(pathological perspective, perhaps because of oedema and effusions during pathological events?)
Limitations/ Contraindications for CT?
Radiation dose (pregnant)
Contrast media allergy
Claustrophobia
Limitations/ Contraindications for MRI?
Very large patients don’t fit
Claustrophobia
Long immobility
Indications for MRI?
Alignment: deformities
Bone: fractures, infiltration by tumour
Cartilage: Arthritis Soft tissue:
Masses * high imaging discrepancy
Proton density: (FYI)
T1 and T2 weighted properties combined
Stir: (FYI)
Short T1 inversion
Poor anatomical definiton
Fat suppression, water enhancement
Fat saturation (FYI)
Suppresses signal from fat, therefore making areas of small anatomical change more evident and increasing over all sensitivity of the examination.
Good definition of ligs and tendons
Gradient echo (FYI)
Fast MRI (essentially a T2 with less definition
2 reasons to do a CT
Complex fractures
Soft tissue pathologies
Tumours
2 reasons to do an MRI
Knee lesions: meniscal damage, ligamentous tears
Disc herniations
What type of scan are these?
Right?
Left?
Right: T2
Left: T1
What type of scan are these?
Right?
Left?
Right: CT soft tissue window
Left: CT bone window
