Improved Depictions of the Anterior Choroidal Artery and Thalamoperforating Arteries on 3D-CTA Images Using Model-based Iterative Reconstruction.

To evaluate the depictability of intracranial small arteries using high-resolution CTA with model-based iterative reconstruction (MBIR). We retrospectively analyzed 21 patients who underwent brain 3D-CTA. Axial and volume-rendered (VR) images were reconstructed from the 3D-CTA raw data using adaptive statistical image reconstruction (ASIR) and MBIR. As a quantitative assessment, intra-arterial CT values of the ICA and contrast-to-noise ratio were measured to evaluate vessel enhancement. Additionally, CT values and standard deviations (SDs) of CT values and signal to noise ratio in white matter parenchyma were measured to evaluate background noise. As a qualitative assessment, the degree of vessel depictability in the anterior choroidal artery (AchoA) and the perforating branches of thalamoperforating arteries (TPA) on VR images using two different reconstruction algorithms was visually evaluated using a 3-point grading system. The CT value of the ICA [605.27± 89.76 Hounsfield units (HU)] was significantly increased and the SD value (i.e., image noise) of the white matter parenchyma [6.79 ± 0.81(HU)] was decreased on MBIR compared with ASIR [546.76 ± 85.27 (HU)] and [8.04 ± 1.08 HU)] (p <.05 for all). Contrast-to-noise ratio of ICA [84.48 ± 20.17] and signal to noise ratio of white matter [6.18 ± 0.75] with MBIR were significantly higher than ASIR [65.98 ± 13.08] and [5.28 ± 0.78] (p < 0.05 for all). In addition, depictions of the AchoA and TPA on VR images were significantly improved using MBIR compared with ASIR (p < 0.05). MBIR allows depiction of small intracranial arteries such as AchoA and TPA with better visibility than ASIR without increasing the dose of radiation and the amount of contrast agent.

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