Unusual Synchronous Arbitrary‐Gate Doppler Spectra Enable Intraoperative Hemodynamic Warning of Cerebral Hyperperfusion Syndrome on Moyamoya Disease

SAGSD enables highly sensitive, multi-position, and contrast-free hemodynamic evaluation of deep cerebral microvasculature. The "mountain" sign, a novel spectral morphology corroborated by quantitative VTI elevation, is a specific intraoperative biomarker strongly associated with CHS, offering a potential predictor for early intervention and improved surgical outcomes.