Figure 1.

Comparison of conventional with time-staggered data acquisition relying on spatial excitation. (A) Conventional data acquisition: the entire sample volume within the r.f. detection coil is utilized to record FIDs with a relaxation delay between scans denoted as d1. The excited region of the sample is depicted in black to indicate that a sizable steady state magnetization is present before excitation and the white dashed rectangle indicates the region for which the signal is detected. The FID is represented by a triangle and [N,P] within the triangle indicates the indirect dimension’s real data point N and its corresponding phase cycling step P. As an example, complex data acquisition (N = 1,2) is combined with a two step phase cycle (P = 1,2) cycle for axial peak suppression^[15]. (B) Time-staggered data acquisition relying on spatial excitation of one slice of the entire volume at a time (highlighted with a white dashed rectangle). Considering t_FID as the time required to detect an FID and d1’ as the relaxation delay between scans, the same steady state magnetization is present as in (A) if d1 + t_FID = 4*(d1’ + t_FID). The transitions from pale grey to grey, then to dark grey and eventually to black (second slice from the top) indicates progressing longitudinal relaxation in a slice while other slices are excited. As a result, NMR time domain data can be acquired more rapidly while ensuring that sufficiently long relaxation times between scans are employed.