4D DSA: technical addition or big revolution?

After the legendary discovery of digital subtraction angiography (DSA) by Mistretta et al in the 1970s,1 technical advances in X-ray processing have enabled us to progressively improve high-quality two-dimensional (2D) DSA images. The subsequent three-dimensional (3D) DSA, a revolutionary advancement, has enabled us to visualize vessels at multiple angles, particularly regarding cerebral aneurysm treatment.2 3 As such, the standard for cerebral vascular visualization is to obtain multiple 2D DSA series and additional 3D DSAs, for a better holistic understanding of cerebral vascular pathologies. However, despite the fact that 3D DSA offers better spatial understanding, 3D DSA images are static, and limited by overlapping arteries and veins. Thus, when the vascular pathology is complex with high flow, an increased number of 2D DSA series becomes necessary to compensate for the loss of temporal resolution. Therefore, a more sophisticated imaging technique is needed for complex vascular pathologies, offering temporal flow information combined with 3D imaging, that is, dynamic time-resolved 3D DSA, or four-dimensional (4D) DSA. Described by Davis et al in 2013,4 the dynamic visualization of cerebral vasculature achieved with 4D DSA became commercially available in 2015 (Siemens Artis Flat Panel Angiography Systems) opening a completely new “universe” to explore in cerebrovascular imaging. 4D DSA can display detailed neurovascular anatomy with temporal resolution, blood velocity quantification, and quantitative perfusion data.5–7 Temporal resolution not only reveals the timing of the blood flow in and out of a vascular structure, but also helps to avoid vascular overlap using the advantages of 2D DSA and 3D DSA at one time. Displaying detailed neurovascular anatomy …