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. Read more about FLAIR sequence.
T1-weighted fluid-attenuated inversion recovery (T1FLAIR) is a relatively new pulse sequence and it provides higher tissue contrast between the gray matter (GM) and white matter (WM) of the brain than T1-weighted SE (T1SE) sequence.
The T2-FLAIR mismatch sign is an imaging finding highly suggestive of isocitrate dehydrogenase mutated (IDH-mut) 1p19q non-codeleted (non-codel) gliomas (astrocytomas). In previous studies, it has shown excellent specificity but limited sensitivity for IDH-mut astrocytomas.
It's all about FAT and WATER
The two basic types of MRI images are T1-weighted and T2-weighted images, often referred to as T1 and T2 images. The timing of radiofrequency pulse sequences used to make T1 images results in images which highlight fat tissue within the body.
T1-weighted FLAIR imaging provides improved lesion-to-background and grey to WM contrast-to-noise ratios. Superior conspicuity of lesions and overall image contrast is obtained in comparable acquisition times.
There are different contrast images in magnetic resonance MRI types. T1-weighted MRI enhances the signal of the fatty tissue and suppresses the signal of the water. T2-weighted MRI enhances the signal of the water.
The relatively high concentration of interstitial water in the periventricular / perivascular regions in combinations with the increasing blood–brain-barrier permeability and plasma leakage in brain aging may contribute to T2/FLAIR WMH despite relatively mild demyelination.
Focal hyperintensities in the subcortical white matter demonstrated by T2-weighted or FLAIR images are a common incidental finding in patients undergoing brain MRI for indications other than stroke. They are indicative of chronic microvascular disease.
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.
Fluid attenuated
This sequence is called FLAIR. Importantly, at first glance FLAIR images appear similar to T1 (CSF is dark). 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.
Specifically, T1 and T2 refers to the time taken between magnetic pulses and the image is taken. These different methods are used to detect different structures or chemicals in the central nervous system. T1 and T2 lesions refers to whether the lesions were detected using either the T1 or T2 method.
A simple mnemonic for this: T1 vs T2 MRI (Mnemonic = WWII or World War II) --> Water is White on a T2 MRI scan More mnemonics: radiologyvibes.com/pages/radiolog…
T2 relaxation always proceeds at a faster rate than T1 relaxation; thus the the T1 relaxation time is always longer than or equal to T2.
White matter T2 hyperintensities in the brain are not specific to MS and are seen in a number of other disorders. They can even be seen in otherwise normal individuals, particularly with increasing age.
Typically (as shown in the first figure), T2 values of tissue are considerably lower than T1 values, i. e., the transverse magnetization decays quicker than the longitudinal relaxation needs for recovery. For most tissues in vivo, T1 varies between about 300 ms and 3 s, while T2 varies between about 10 ms and 200 ms.
White matter hyperintensities (WMHs) are lesions in the brain that show up as areas of increased brightness when visualised by T2-weighted magnetic resonance imaging (MRI). WMH's are also referred to as Leukoaraiosis and are often found in CT or MRI's of older patients.
Background. Fluid attenuated inversion recovery (FLAIR) vascular hyperintensity (FVH) is a novel radiographic marker detected in acute ischemic stroke (AIS) patients, which is linked to slow blood flow and potentially salvageable brain tissue.
T1 and T2 (top two thoracic nerves) feed into nerves that go into the top of the chest as well as into the arm and hand. T1 is also part of the Brachial Plexus. T3, T4, and T5 feed into the chest wall and aid in breathing.
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).
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.
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).
High signal of melanoma metastases on T1-weighted images may result not only from the presence of melanin, but also bleeding (methemoglobin phase), which often coexists with such lesions.
In pure water T2 is long, about 3-4 seconds because water molecules move considerably faster than the Larmor frequency. The rapid motion results in the T1 and T2 being about the same in pure water. In solutions of macromolecules and tissues the relaxation rate is much faster, i.e., the T2 time is shorter.
1 Answer. Explanation: The given figure shows the variation of Fermi-Dirac distribution with energy E. In this case, T2 > T1, according to the expression: FFD(E) =( frac{1}{efrac{E-E_F}{nT}+1}).