No observation of DIANA signals in rats at 7.0 and 17.2 Tesla

Motivation: Direct Imaging of Neuronal Activity (DIANA) was proposed by Toi et al. in Science 2022. Before DIANA can be adopted, key findings must be reproduced. Goal(s): Independent reproduction of the results shown in supplemental Figure 26 of Toi et al. Approach: Rats were scanned at 7.0T and 17.2T using a visual paradigm consisting of a 10ms blue flash every 200ms. Results: No DIANA signal was detected, even though the temporal signal to noise ratio was sufficient to detect signal changes of 0.1%. However, a slow hemodynamic signal, much larger than the expected DIANA signal, was observed between measurements with and without stimulus. Impact: Our failure to detect a DIANA signal in rat at 7.0T and 17.2T, echo's findings by Hodono et al. (Imaging Neuroscience) and Choi et al. (bioRxiv), indicating DIANA is not ready for use in neuroscientific studies.