. Author manuscript; available in PMC: 2012 May 13.

Published in final edited form as: Magn Reson Med. 2010 Nov 30;65(2):377–384. doi: 10.1002/mrm.22673

Table 1.

Estimated accuracy and precision of T₂s and associated weights from multiexponential fits.

Group		T_2,PG	T_2,LB	w_PG	w_LB
Young	Accuracy	0.90	0.31	2.11	−0.63
Young	Precision	1.44	0.29	1.75	0.52
Mature	Accuracy	0.50	0.40	1.84	−0.82
Mature	Precision	1.60	0.32	1.40	0.63

Simulations results for accuracy and precision. Accuracy is defined as average percent error. Precision is reported as the coefficient of variation (CV), defined as the standard deviation over 100 noise realizations divided by the input parameter value × 100. Reliability (not shown), defined as correctly identifying the number of input T₂ components, was 100 percent for both young and mature tissue. Reported values are estimated using the average experimental SNRs of 3,365 and 3,587, for young and mature BNC, respectively. In each case, 100 noise realizations using the average T₂s and associated weights as input values were simulated. Simulation input values for the PG component, C_PG, and the loosely-bound water component, C_LB, for young and mature tissue were (T₂ ms, % magnetization): young C_PG = (27ms, 23%) and C_LB = (88ms, 77%); mature C_PG = (20ms, 31%) and C_LB = (63ms, 69%). Note that in all cases both accuracy and precision were on the order of 2% or less.