Abstract: The present invention generally relates to systems and methods for imaging or determining nucleic acids in cells or other samples. In some cases, the transcriptome of a cell may be determined. Certain embodiments are generally directed to determining nucleic acids and other targets in a sample at relatively high resolutions. For instance, nucleic acid probes may be applied to sample, and binding of the nucleic acid probes to a target may be amplified using primary and secondary amplifier nucleic acids. In some cases, there is a maximum number of amplifier nucleic acids that can be bound to a target, e.g., the binding is saturatable, and cannot grow indefinitely, even in the presence of abundant reagents. This may be advantageous, for example, for controlling the brightness of each binding event, controlling the size of the amplified regions (e.g., during imaging), and/or for limiting the degree of amplification noise (i.e. the final variation in amplified signal from molecule to molecule), etc.