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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.

keith@bwh.harvard.edu

	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.

	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