As the authors point out, other modalities can provide some additional data that cannot currently be obtained using fUS, ULM, and fULM. For example, optical imaging can potentially provide greater spatial and temporal resolution, but is inherently limited to optically accessible tissues and is therefore not universally practicable. Similarly, electrophysiological recording can achieve much greater temporal resolution, but detection is often restricted to the vicinity of the recording probe, and is necessarily more invasive. The key advantages of fULM are its non-invasive application and more pragmatic benefits (lower cost and portability), while still providing sufficiently detailed data. As another tool in the ever-expanding neuroscientist toolbox, fULM can only help facilitate new discoveries and could certainly be combined with other existing methods.
Ultimately, the methods and data presented in this study represent a considerable technical achievement and have pushed the limits of what is achievable in terms of the spatiotemporal resolution of ultrasound imaging. Renaudin et al. have demonstrated the potential of ultrasound neuroimaging to provide the level of detail required for meaningful exploration of brain hemodynamics; the next challenge will be to adapt these methods for clinical and other applications.