Table 5. Normal white and gray matter, worked example (SE_TR/TE = 600/20 ms sequence).

	ρm	T1	T2
White Matter (WM)	0.61 g/cc	510 ms	67 ms
Gray matter (GM)	0.69 g/cc	760 ms	77 ms
Tissue property fractional difference (relative to WM)	$\frac{\Delta {\rho }_{\text{m}}}{{\rho }_{\text{m}}}=\frac{0.08}{0.61}=13\%$	$\frac{\Delta T_1}{T_1}=\frac{250}{510}=49\%$	$\frac{\Delta T_2}{T_2}=\frac{10}{67}=15\%$
Signal STP (% maximum signal)	${\text{S}}_{{\text{ρ}}_{\text{m}}}={\text{ρ}}_{\text{m}}61\%$	$\frac{T_1}{\mathrm{TR}}=0.85$, ${\text{S}}_{{\text{T}}_1}=\left(1-{\text{e}}^{-\frac{\text{TR}}{{\text{T}}_{\text{1}}}}\right)\text{=}69\%$	$\frac{T_2}{\mathrm{TE}}=0.30$, ${\text{S}}_{{\text{T}}_2}={\text{e}}^{-\frac{\text{TE}}{{\text{T}}_{\text{2}}}}\text{=74}\%$
Sequence weighting, $\text{s}{W}_{\mathrm{TP}/\mathrm{SE}/{\text{C}}_{\mathrm{fr}}}$	$\text{s}{W}_{{\rho }_m/\mathrm{SE}/{\text{C}}_{\mathrm{fr}}}=100\%$	$\text{s}{W}_{T_1/\mathrm{SE}/{\text{C}}_{\mathrm{fr}}}=-\frac{\mathrm{TR}}{T_1}\frac{{\text{e}}^{-\frac{\text{TR}}{{\text{T}}_{\text{1}}}}}{\left(1-{\text{e}}^{-\frac{\text{TR}}{{\text{T}}_{\text{1}}}}\right)}=-36\%$	$\text{s}{W}_{T_2/\mathrm{SE}/{\text{C}}_{\mathrm{fr}}}=\frac{\mathrm{TE}}{T_2}=22\%$
Sequence weighting ratio, $s{W}_{\mathrm{SE}}^{\text{r}}({\rho }_{\text{m}}:T_1:T_2)$	51%	−30%	19%
Image weighting, $\text{i}{W}_{\mathrm{TP}}=s{W}_{\mathrm{TP}}·\frac{\mathrm{\Delta TP}}{\mathrm{TP}}$	$\text{i}{W}_{{\rho }_{\text{m}}}=s{W}_{{\rho }_{\text{m}}}·\frac{\mathrm{\Delta \rho }}{\rho }\text{=}51\times 13\text{=}633$	$\text{i}{W}_{T_1}=s{W}_{T_1}·\frac{\Delta T_1}{T_1}\text{=}-30\times 49\text{=}-\text{1470}$	$\text{i}{W}_{T2}=s{W}_{T2}·\frac{\Delta T_2}{T_2}\text{=}19\times 15\text{=285}$
Image weighting ratio, $\text{i}{W}_{\mathrm{SE}}^{\text{r}}({\rho }_{\text{m}}:T_1:T_2)$	27%	−61%	12%