Time to Echo (TE) is the time between the delivery of the RF pulse and the receipt of the echo signal. Tissue can be characterized by two different relaxation times – T1 and T2. T1
(longitudinal relaxation time)
is the time constant which determines the rate at which excited protons return to equilibrium.
How do I know if I have T1 or T2 MRI?
The best way to tell the two apart is to look
at the grey-white matter
. T1 sequences will have grey matter being darker than white matter. T2 weighted sequences, whether fluid attenuated or not, will have white matter being darker than grey matter.
What does T1 and T2 stand for?
Time to Echo (TE) is the time between the delivery of the RF pulse and the receipt of the echo signal. Tissue can be characterized by two different relaxation times – T1 and T2. T1
(longitudinal relaxation time)
is the time constant which determines the rate at which excited protons return to equilibrium.
What’s bright on T1 MRI?
The list of entities associated with a high signal intensity on T1-weighted images is extensive and classically includes
fat, proteins, hemorrhage, melanin and gadolinium
.
What is the difference between T2 and T2 * in MRI?
T2* can be considered an “observed” or “effective” T2, whereas the first T2 can be considered the “natural” or “true” T2 of the tissue being imaged.
T2* is always less than or equal to T2
. T2* results principally from inhomogeneities in the main magnetic field.
What is the difference between T1 and T2 lesions?
A T1 MRI image supplies information about current disease activity by highlighting areas of active inflammation. A T2 MRI image provides information about disease burden or lesion load (the total amount of lesion area, both old and new).
What does T1 hypointense mean?
T1 -hypointense lesions (T1-black holes) in
multiple sclerosis (MS)
are areas of relatively severe central nervous system (CNS) damage compared with the more non-specific T2-hyperintense lesions, which show greater signal intensity than normal brain on T2-weighted magnetic resonance imaging (MRI).
What is a T1 and T2 hyperintense lesion?
T1 lesions were defined as
regions with a signal intensity similar to or reduced to the signal intensity of gray matter
and corresponding to a hyperintense region on T2-weighted MRI. Hyperintense–T2 lesions were defined as sharply demarcated regions of high signal intensity compared with surrounding brain tissue.
What does increased T2 signal mean?
Patients with an increased T2 signal intensity are likely to have
a more severe initial neurological deficit
but will have relatively minimal early neurological deterioration.
What does increased Stir signal mean?
The STIR sequence, designed to suppress signal from fat, also enhances the
signal from tissue with long T1 and T2 relaxation times
, such as neoplastic and inflammatory tissue.
What shows up bright on T1?
On a T1-weighted scans show
tissues with high fat content (such as white matter)
appear bright and compartments filled with water (CSF) appears dark.
What does high T1 signal mean?
T1 weighted image – Pathology (spine)
Loss of the normal high signal in the bone marrow indicates loss of normal fatty tissue and
increased water content
. Abnormal low signal on T1 images frequently indicates a pathological process such as trauma, infection, or cancer.
Is blood bright on T1?
The first two mnemonics use the first letters of the words and word pairs to denote the signal characteristics of blood at each stage as isointense (I), bright (B), or dark (D). The first bold letter in each pair
denotes the typical T1 signal finding
, while the second denotes the T2 signal change.
What is T2 weighted MRI used for?
For body imaging, T2*-weighted sequences are used to depict (a)
hemorrhage in various lesions
, including vascular malformations, (b) phleboliths in vascular lesions, and (c) hemosiderin deposition in joints in conditions such as hemophilic arthropathy (Fig 7 ) and pigmented villonodular synovitis (Fig 8).
What is T2 value MRI?
T2
reflects the length of time it takes for the MR signal to decay in the transverse plane
. A short T2 means that the signal decays very rapidly. So substances with short T2’s have smaller signals and appear darker than substances with longer T2 values.
What does T2 hyperintensity mean on an MRI?
A hyperintensity or T2 hyperintensity is
an area of high intensity on types of
magnetic resonance imaging (MRI) scans of the brain of a human or of another mammal that reflect lesions produced largely by demyelination and axonal loss.
