<scp>DynaTOF</scp> : Time‐Resolved Noncontrast Cerebral <scp>MR</scp> Angiography Using Spatially Modulated <scp>RF</scp> Saturation

PURPOSE: To develop a time-resolved extension of three-dimensional time-of-flight MR angiography, termed Dynamic TOF (DynaTOF), that exploits intrinsic RF saturation behavior to enable noncontrast visualization of cerebrovascular hemodynamics. METHODS: DynaTOF was implemented by varying flip angle, repetition time (TR), and slab-selective RF excitation profile to modulate longitudinal magnetization saturation and encode relative inflow timing. Data were acquired using a short-TR protocol combined with deep-learning reconstruction to ensure scan efficiency. Five healthy volunteers underwent DynaTOF and pulsed arterial spin labeling (PASL) MRA. Five patients with intracranial arteriovenous malformations (AVMs) were scanned to evaluate clinical feasibility and compare temporal patterns with digital subtraction angiography (DSA). Analyses included inflow-time characterization, cross-correlation with PASL, region-of-interest assessment of arterial, nidus, and venous structures, as well as apparent SNR and contrast-to-noise ratio (CNR) quantification. RESULTS: in approximately 1 min, supporting flexible parameter sweeps within routine clinical time constraints. CONCLUSION: DynaTOF offers a noninvasive approach for time-resolved characterization of cerebrovascular flow while preserving TOF-like spatial resolution.