- T1 weighted MRI
- T2 weighted MRI
- STIR (Short T1 Inversion Recovery), is a fat suppression technique. STIR sequencing is also very useful for looking at structures such as the adrenal glands, bone marrow and fatty tumours.
- FLAIR (Fluid Attenuation Inversion Recovery), a similar technique to suppress water. FLAIR is good for imaging cerebral oedema and periventricular or cortical lesions in conditions such as multiple sclerosis.
- MRI creates images by picking up different signal intensities from different tissues depending on the hydrogen, or more specifically, proton content of that tissue. On normal MRIs (proton density or PD weighted), the greater the hydrogen content, the brighter the image.
- But radiologists and radiographers can programme the MRI machine to only pick up a certain direction of proton movement.
- T1 is when they programme the machine to only look at the longitudinal movement of protons. T1 images are usually used to look at normal anatomical details.
- T1 is best for looking at brain structure because fat appears very bright and bone marrow contains a great deal of fat.
- T2 is the transverse movement of protons and is usually used to look at pathology because most tissues involved in disease tend to have a higher water content than normal.
- Water and fluid are brighter on T2- ideal for tissue oedema.
- White matter appears a light grey in T1 and a dark grey in T2.
- Grey matter appears grey in both.
- Cerebrospinal fluid (CSF) appears black in T1 and white in T2.
FLAIR is good for dectection of Multiple sclerosis (MS, is an inflammatory disease in which the insulating covers of nerve cells in the brain and spinal cord are damaged. Wikipedia).