Improved Arterial Visualization in Cerebral CT Perfusion–Derived Arteriograms Compared with Standard CT Angiography: A Visual Assessment Study

Abstract

BACKGROUND AND PURPOSE:Invasive cerebral DSA has largely been replaced by CTA, which is noninvasive but has a compromised arterial view due to superimposed bone and veins. The purpose of this study was to evaluate whether arterial visualization in CTPa is superior to standard CTA, which would eliminate the need for an additional CTA scan to assess arterial diseases and therefore reduce radiation dose.

Wavelet-Based Angiographic Reconstruction of Computed Tomography Perfusion Data

“…The manifold advantages of WB-CTP postprocessing have been demonstrated in precise depiction of the intracranial arteries equivalent to artCTA, 8,12 in timing-invariant imaging of collateral vessels 19 as well as their facilitated color-coded evaluation in acute ischemic stroke. 20 Potentially decision-relevant parameters can be drawn from postprocessed WB-CTP data, for example, the velocity of collateral filling 21 and a close definition of the thrombus burden, 11 potentially supporting the prediction of clinically relevant endpoints such as stent-retriever thrombectomy outcomes.…”

“…Novel postprocessing algorithms, however, can create highquality CT angiographies from the initially acquired CTP data. [8][9][10][11][12] As CTP is a dynamic examination, it does not only cover the arterial but also the venous phase, which implies the potential of these CTPderived angiographic techniques to detect CVST better than artCTA. 13 Among these approaches, wavelet-transformed CTA (waveletCTA) has shown an excellent signal-to-noise ratio 14 and the ability to accurately differentiate between arterial and venous vessels.…”

Total Bolus Extraction Method Improves Arterial Image Quality in Dynamic CTAs Derived from Whole-Brain CTP Data

“…Finally, the skull mask that was used for the ToBE method introduced some artifacts in the arteries near the cranial base, that were not present in the standard dCTAs, since this method does not use skull masking. A solution to this problem would be to use the ToBE method without bone masking, since bone is automatically suppressed [18, 20]. However, in this study we used the bone mask to suppress high intensities that could result from small misalignments of the sequential CTP volumes and might reduce depiction of arteries.…”

“…This method is based on a method proposed by Mendrik et al [18, 20] that derives 3D angiograms from CTP data. These 3D angiograms (vessel enhanced volumes) were derived from the CTP data by quantifying the total change in Hounsfield units (HU) over all temporal volumes (total bolus), using the absolute area under the first temporal derivative curve as described in [18].…”

“…Therefore, cerebral arteries, and in particular arteries with a small diameter, are more difficult to assess. Several methods have been proposed to derive vascular information from CTP scans [17–19] of which some are with a quality comparable to standard 3D CTA [19, 20]. However, these methods do not provide full 4D dynamic CTA images but instead provide a 3D image showing the vasculature.…”