Researchers compared two imaging methods for mapping blood vessels in the brain's circle of Willis, finding that time-of-flight magnetic resonance angiography (TOF-MRA) produces virtually identical results to computed tomography angiography (CTA) for hemodynamic modeling. In 19 cardiac surgery patients, both methods yielded similar arterial measurements (difference of 0.2 mm²) and pressure calculations during computational fluid dynamics simulations, including scenarios mimicking carotid artery blockage. This finding could eliminate the need for radiation exposure and contrast agents required by CTA, offering a safer alternative for routine brain vascular assessment. The implications extend beyond imaging preference to personalized medicine, where accurate hemodynamic modeling helps predict stroke risk and optimize surgical planning. Current clinical workflows heavily rely on CTA despite its invasive nature, but this research suggests TOF-MRA could serve as a drop-in replacement for many applications. However, the study's small sample size of 19 patients and focus on older surgical candidates limits broader generalizability. As a preprint awaiting peer review, these findings require validation in larger, more diverse populations before clinical adoption. This represents solid confirmatory evidence supporting the shift toward radiation-free vascular imaging, though not paradigm-shifting given MRA's established capabilities.