Optogenetic fMRI studies have traditionally required significant scan averaging to achieve signal-to-noise ratios sufficient for whole-brain functional network mapping. As a result, more scan time is required, and measurements may not directly translate to accompanying behavioral paradigms that employ a single stimulation. Here, we used a SPION-based MRI contrast agent to enable single-scan functional network mapping with CBV during optogenetic stimulation of the thalamic submedial nucleus. Measurement of CBV led to significant activations detected at the site of stimulation and downstream mono- and polysynaptically connected regions. In comparison, single-scan BOLD measurements led to minimal detectable responses to stimulation.