A Comparison of 4D DSA with 2D and 3D DSA in the Analysis of Normal Vascular Structures in a Canine Model

BACKGROUND AND PURPOSE:4D DSA allows viewing of 3D DSA as a series of time-resolved volumes of a contrast bolus. There is no comparison of the accuracy of the anatomic information provided by 4D DSA with that available from conventional 2D and 3D DSA. Our purpose was to make this comparison by using a canine model.MATERIALS AND METHODS:2D, 3D, and 4D DSA acquisitions were performed in 5 canines from 3 catheter positions in the common carotid artery yielding 15 2D, 15 3D, and 15 4D datasets. For each territory, 3 vascular segments were chosen for comparison. Images were reviewed by 2 experienced neuroradiologists and were graded by the ability to visualize a segment, its filling direction, and preferred technique. Two visualization modes for 4D DSA were compared (volume-rendering technique and MIP).RESULTS:4D DSA was preferred in 73.9% of the image sets; 2D, in 22.7%; and 3D, in 3.4%. 4D DSA MIP rendering yielded superior visualization of very small vessel details; the 4D DSA volume-rendering technique offered superior depth and overlap information and better visualization of the surface details of the vasculature.CONCLUSIONS:In this study, 4D DSA was preferred over 2D and 3D DSA for analysis of normal vasculature. The ability to provide any view of a vascular territory at any time during passage of a contrast bolus seems likely to reduce the need for many 2D acquisitions during diagnostic and therapeutic procedures. This then potentially translates into a reduction in radiation and contrast dose.

4D DSA provides the ability to create a series of time-resolved volumes of vasculature so that the passage of a contrast bolus may be viewed in 3D at any time and from any angle. Traditional 3D DSA acquisitions provide volumetric anatomic information but are not time-resolved. The overlap of vasculature in these 3D images often makes it difficult to analyze details (eg, angioarchitecture of an AVM nidus). To overcome this problem, multiple 2D DSA acquisitions at different angles are often necessary. The 4D algorithm applied to data from a rotational acquisition, obtained by using an injection protocol that starts the injection shortly after rotation of the C-arm rather than simultaneous with its rotation, results in a series of 4D DSA volumes that provides a user with the ability to view both anatomic information and contrast dynamics.¹ The anatomic information provided by this technique has not, to our knowledge, been compared with that provided by conventional 2D and 3D DSA images. In this study, we aimed to assess the ability of 4D DSA to depict vascular anatomy. Our methods also aimed to acquire data that would allow us to make judgments as to whether the content was superior to and/or complementary to that of conventional DSA studies. We believed that this comparison was important because the ability to view relevant vasculature at any time and at any angle with a 4D reconstruction should result in less need to acquire multiple 2D series in both diagnostic and interventional procedures, thereby leading to reductions in both x-ray and contrast medium doses.