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

Abstract

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.

Fig 1.

Example of the vasculature on anteroposterior 2D DSA projections for each catheter position: proximal (A), middle (B), and distal (C). These show the decrease in the vascular complexity as the injection site is moved from proximal to most distal. The magnification factor for the images increases, moving from proximal to most distal.

Fig 2.

Illustration of 4D DSA reconstruction. No x-ray delay between contrast injection and rotational image acquisition results in contrast flow or inflow being visible in the rotational projections (A–C). Through a 2-step reconstruction process, this flow information is encoded into the 3D DSA for every projection, effectively creating a 4D DSA. This allows viewing of the contrast bolus passage at any desired angle at any time during the bolus passage. D–F, View of the bolus passage at 3 projection angles at 3 different time points. G–I, View of the bolus passage at 3 angles not present in the projections, again at 3 different time points. The figures correspond to sample angle projections selected to match the 2D acquisitions, even though once 4D images are reconstructed, views are available from any angle.

Fig 3.

A–C, Example of the pictorial reference form provided to the image reviewers identifying the vascular segments to be evaluated: proximal (A), middle (B), and distal (C) catheter positions on anteroposterior projections. D, Evaluation form and scales used for scoring of the images.