We try using the pulse sequence shown in Figure P12.2 to image the human brain. A π/2 pulse is applied to the brain while in equilibrium.

Figure P12.2 Pulse sequence for Problem 12.15

Suppose the duration of the RF pulse is negligible. The FID signal is sampled at time τ and the pulse repetition interval is TR.

(a) We use T T_RR= 6, 000 ms, τ = 20 ms. Is this a T T₂-weighted contrast? If not, what modification isneeded to obtain T T₂-weighted images?

(b) Sketch the modified pulse sequence.

(c) Provide some reasonable values of τ , T T_R tip angle, and other parameters that should be used in the new pulse sequence.