how long is tr
TE is always shorter than TR. A short TR = value approximately equal to the average T1 value, usually lower than 500 ms. A long TR = 3 times the short TR, usually greater than 1500 ms. A short TE is usually lower than 30 ms. A long TE = 3 times the short TE, usually greater than 90 ms.
In clinical practice: 1  TE is always shorter than TR. 2  A short TR = value approximately equal to the average T1 value, usually lower than 500 ms. 3  A long TR = 3 times the short TR, usually greater than 1500 ms.  A short TE is usually lower than 30 1  ms. A long TE = 3 times the short TE, usually greater than 90  ms.