Computational Fluid Dynamics Analysis of Contrast Agent Distribution in Acute Large Artery Occlusive Stroke: A Preliminary Proof-of-Concept Study

Figures

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  Fig. 1.. Pre- and post-procedural CTA and DSA images of patients 1 and 2 undergoing mechanical thrombectomy. Patient 1 (A–E): (A) CTA showing proximal occlusion of the left ICA. (B) Common carotid angiography revealing a flame-like remnant. (C) ICA angiography demonstrating a slender, elongated appearance in the mid-C1 segment. (D,E) Post-stenting images showing successful recanalization of the vessels. Patient 2 (F–J): (F) CTA showing severe stenosis or possible occlusion of the left ICA C1 segment. (G) CCA angiography showing string-like narrowing of the mid-portion of the ICA C1 segment. (H) After carotid artery stenting, the distal left ICA C1 segment remains occluded. (I,J) Following placement of a second stent in the distal left ICA C1 segment, complete recanalization was achieved. CTA, computed tomography angiography; DSA, digital subtraction angiography; ICA, internal carotid artery; CCA, common carotid artery.

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  Fig. 2.. Pre- and post-procedural CTA and DSA images of patients 3 and 4 undergoing mechanical thrombectomy. Patient 3 (A–E): (A) CTA showing occlusion of the left ICA. (B) CCA angiography revealing a flame sign at the proximal ICA with a fluid level. (C) Selective ICA angiography demonstrating occlusion in the C4 segment. (D,E) Post-thrombectomy images showing complete recanalization of the vessels. Patient 4 (F–J): (F) Proximal occlusion of the right CCA. (G) CCA angiography showing contrast agent retention in the CCA with a fluid level. (H) Selective ICA angiography indicating occlusion in the C7 segment. (I,J) Post-thrombectomy images showing complete recanalization of the ICA.

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  Fig. 3.. Velocity waveform for the common carotid artery over one cardiac cycle.

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  Fig. 4.. Comparison of CTA and DSA images in patients with ICA dissection and distal ICA occlusion. (A–D) show CTA images of patients 1, 2, 3, and 4, respectively. (E–H) show the corresponding DSA images. Patients 1 and 2 had ICA dissection. In patient 2, because there is no complete occlusion, typical linear signs are observed on both the CTA (B) and DSA (F) images. In patient 1, complete occlusion is evident on CTA (A) and common carotid artery DSA (E), which show a residual end resembling a candle flame at the origin of the ICA. However, selective internal carotid angiography reveals linear signs, confirming the diagnosis of dissection. Patients 3 and 4 had distal ICA embolism. In patient 3, the occlusion is located at the C4 segment. CTA (C) and common carotid artery DSA (G) show a residual end resembling a candle flame at the origin of the ICA. However, selective ICA DSA shows that the occlusion does not extend to the C1 segment but gradually approaches the residual end, ultimately confirming its precise location. Patient 4 had distal ICA embolism combined with external carotid artery embolism. Surgical findings confirmed that the occluded segment is at the C7 segment; however, CTA…

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  Fig. 5.. Characteristics of vortex flow and distal dead space at the C1 segment in DSA and CFD simulations. Numbered cross-sections established on the vascular model: 1, common carotid artery (CCA); 2, carotid bifurcation (trifurcation plane); 3, internal carotid artery (ICA) at the proximal C1 segment; 4, ICA at the mid-C1 segment; 5, external carotid artery (ECA); 6, ICA at the distal C1 segment. The curves in (H) and (B) are colour-matched to these numbered cross-sections. Fig. 5-1. Changes in CFD-simulated velocity. During the early phase of DSA (frame 13, A), vortex flow is observed at the ICA origin. The CFD velocity profile (B) reveals vortex formation at the early stage of the ICA, with a height comparable to that observed in DSA. Similarly, the velocity vector diagram of the bifurcation plane (C) indicates an elliptical vortex at the ICA origin. In the later phase of DSA (frame 26, D), the contrast agent reaches the farthest point within the ICA, and a distinct blood-contrast-agent interface is observed at the ICA origin. The CFD simulation velocity profile (E) reveals that blood flow reaches its maximum distance in the later stage of the ICA, with a height comparable to that…

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  Fig. 6.. Contrast agent distribution in CFD simulations. In the supine position (A), during the later phase of DSA (frame 26, B), the contrast agent reaches the farthest point within the ICA, where it accumulates at the ICA origin, forming a blood-contrast-agent interface. Using a two-phase turbulent flow model for CFD simulations, the volume-rendered image of the contrast-agent volume fraction shows a typical liquid interface at the ICA origin (C), consistent with the DSA findings. When the head is elevated by 14° (D), the blood-contrast agent interface from the later DSA (E) remains visible, and the CFD simulation also demonstrates that the liquid interface changes accordingly with the angle (F).

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  Fig. 7.. CFD simulation results at different occlusion locations. Fig. 7-1. CFD models and cross-sections for different occlusion locations. (A–D) show occlusion model at the C1, C2, C4, and C7 segments of the ICA, respectively. Each model contains cross-sections established at identical anatomical locations. The CCA cross-section is located within the CCA. Three ICA cross-sections (ICA 1, ICA 2, and ICA 3) are positioned sequentially from proximal to distal, beginning at the origin of the C1 segment of the ICA. The cross-section is located within the ECA, and the trifurcation cross-section spans the carotid bifurcation. Fig. 7-2. CFD simulations showing velocity profiles and velocity cloud maps for different occlusion locations. (A–D) present the velocity profiles representing the velocity line graphs and curves of blood flow at the farthest point reached in the ICA following occlusion at C1, C2, C4, and C7, respectively. (E–H) represent the corresponding velocity cloud maps at cross-section 4 when blood flow reaches its farthest point in the ICA after occlusion at C1, C2, C4, and C7, respectively. Fig. 7-3. CFD simulations of pressure cloud maps and wall shear stress cloud maps for…