Items tagged “t1”
7 results found
T1 relaxation time
The T1 relaxation time, also known as the spin-lattice relaxation time, is a measure of how quickly the net magnetisation vector (NMV) recovers to its ground state in the direction of B0. The return of excited nuclei from the high energy state to the low energy or ground state is associated with...
Dural metastases mimicking meningiomas
Diagnosis almost certain
Published 14 Nov 2014
The Ernst angle is the flip angle that maximizes signal in T1-weighted sequences that have a short repetition time (TR). When the TR is very short, the best flip angle to maximize signal can be quite small. Choosing the Ernst angle in this setting can increase signal by several fold. However, i...
MRI brain (summary)
This is a basic article for medical students and other non-radiologists MRI brain is a specialist investigation that is used for the assessment of a number of neurological conditions. It is the main method to investigate conditions such as multiple sclerosis and headaches, and used to character...
T1 values (1.5 T)
T1 values are a few hundred milliseconds (ms) for most tissues examined. The following are approximate T1 values (ms) of several tissues for B0 = 1.5 T fat = 260 liver = 500 muscle = 870 brain white matter = 780 brain grey matter = 920 CSF = 2500 Tissues that will have high signal in T1-...
Factors affecting T1
Factors affecting T1 and T2 relaxation times of different tissues are generally based on molecular motion, size and interactions. The protons giving rise to an NMR signal are mainly those in cell water and lipids (i.e. protons that are free to move), while those in protein and solids usually do...
Molecular tumbling rate effects on T1 and T2
The average rate at which molecules tumble (and therefore T1 and T2 time) is related to the molecular size. Small molecules (e.g. water/CSF) have a broad distribution of motional frequencies with poor matching with the Larmor frequency and therefore have long T1 values. Medium sized molecules (e...