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Fig. 1A —Experimental single-breath-hold sequence. Ultrafast experimental single-breath-hold single-shot fast spin-echo MRI T2 map obtained with generic Carr-Purcell-Meiboom-Gill sequence. Top line represents spikes in radiofrequency pulses that are in reality selective. Next two lines depict read gradient Gx and encoding gradient waveforms as function of time. Phase-encoding waveform Gy(1) pertains only to first acquisition. Three acquisitions for obtaining three effective echoes are performed in this example. Last two acquisitions are depicted only by their encoding waveforms Gy(2) and Gy(3), radiofrequency and read gradient being kept constant between acquisitions. Signal acquisition periods are represented by rectangles positioned between half-sine encoding and rewinding impulses. Principle of proposed protocol is to shift by a certain number of echo spaces (two echo spaces in this example) acquisition windows and encoding waveform from one acquisition to next, increasing effective echo time by same amount of time. To guarantee that recovery of longitudinal magnetization is not perturbed, sufficient number of dummy echoes (four echoes in this example) with no encoding or signal acquisition are added at end of original Carr-Purcell-Meiboom-Gill sequence. Sequence thus is always of same length and produces same overall action on longitudinal magnetization, ensuring images are void of variable T1 contrast enhancement.