Neuroimaging Primer

Keith A. Johnson, M.D., Harvard Medical School

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A simplified tabulation of tissue image characteristics:

Normal tissue
MR-T11 MR-T21 xray-CT2
dense bone dark dark bright
air dark dark dark
fat bright bright dark
water dark bright dark
brain "anatomic"3 interm. interm.

1. Bright means high signal intensity, dark means low, and interm. means intermediate.

2. Bright means high density/high attenuation of x-rays, dark means low.

3. Grey matter appears grey, white matter white.

Abnormal tissue
MR-T1 MR-T2 xray-CT enhancement1
infarct dark bright dark subacute
bleed bright2 bright2 bright no
tumor dark bright dark3 yes
MS plaque dark bright dark4 acute

1. Blood brain barrier leak. For MR, gadolinium; for CT, iodinated contrast material.

2. Unless very fresh or very old.

3. Unless calcified.

4. Often isodense.

This guide is intended for teaching purposes only. (Additional information on MR signal in brain, or on basic principles of MR)

Interpretation of neuroimaging should be performed by qualified professionals.