mri interpretation Flashcards
what makes an mri successful
mri is good for patients who remain motionless
when do you use mri
to scan organs/anatomical structures that do not move (e.g. brain) OR that can be kept still (e.g. bone marrow, musculoskeletal system) OR that move involuntarily (e.g. bowels and heart)
note: bone marrow is more visible in mri than bone cortex
* to see bone cortex, x rays or ct scans are better
ct vs mri
ct: white areas for high desnity tissues (e.g. bone)
mri: white areas for high signalling tissues (e.g. CSF)
t1 vs t2 weighted mri scans
t1 weighted: ONLY areas of fat appear white (e.g. subcutaneous fat)
t2 weighted: BOTH fat and water appear white (e.g. CSF also appears white)
what indicates a pathology
t1 weighted: abnormally low signal (darker areas) indicates trauma, infection or cancer
t2 weighted: abnormally bright areas indicate trauma, infection or cancer
contrast agent commonly used in mri
gadolinium (given intravenously/directly into a body part, specifically for joints)
note: gandolinium enhances and brightens abnormal tissue (e.g. inflamed/cancerous tissue) as they are usually more vascular
* gandolinium is NOT retained by normal myocardial tissue, but there will be delayed enhancement of the heart if there is cell death in that area
what are the different mri planes
axial, sagittal, coronal
patient 1 has gradually worsening headaches and seizures. what is their diagnosis?
https://www.radiologymasterclass.co.uk/tutorials/mri/mri_system#top_6th_img
brain tumour
patient 2 has sudden onset of left hemiplegia. what is their diagnosis?
https://www.radiologymasterclass.co.uk/tutorials/mri/mri_system#top_6th_img
acute cerebral infarct
orientation of mri scans
left is shown on the right side!
mri safety notes
- no loose metal objects
- no pacemakers, metallic implants, no neurostimulators
- avoid MRI during pregnancy (especially first trimester)
