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. 2022 Jan 28;12(2):338.
doi: 10.3390/diagnostics12020338.

Metallic Component Preserving Algorithm Based on the Cerebral Computed Tomography Angiography in Aneurysm Surgery

Jina Shim  1 , Su Hwan Lee  2 , Youngjin Lee  3 , Kyu Bom Kim  4 , Kyuseok Kim  4
Affiliations

Metallic Component Preserving Algorithm Based on the Cerebral Computed Tomography Angiography in Aneurysm Surgery

Jina Shim et al. Diagnostics (Basel). .

Abstract

The purpose of this study was to investigate the viability of the proposed method in preventing the loss of metallic components including the clip and coil in cerebral computed tomography angiography (CTA). Forty patients undergoing surgery for aneurysms carried metallic materials. The proposed method is based on conventional bone subtraction CTA (BS-CTA) system. Briefly, the position of metal components was determined using the threshold value and a region of interest (ROI). An appropriate threshold was used to separate the background from the target materials based on the Otsu method. A three-dimensional (3D) rendering was performed from the proposed BS-CTA data carrying the extracted target information. The accuracy of clip and coil region measured using the dice similarity coefficient (DSC) and bidirectional Hausdorff distance (HD) is reported. The metallic components of the proposed BS-CTA were significantly visualized in various patient cases. Quantitative evaluation using the proposed method is based on the mean DSC of 0.93 with a standard deviation (SD) of ±0.05 (e.g., maximum value = 0.99, minimum value = 0.75, 95% confidence interval (CI) = 0.91 to 0.95, and all p < 0.05). The mean HD was 1.50 voxels with an SD of ± 0.58 (e.g., maximum value = 5.95, minimum value = 0.12, 95% CI = 1.10 to 1.90, and all p < 0.05). The proposed method demonstrates effective segmentation of the metallic component and application to the existing conventional BS-CTA system.

Keywords: aneurysm; bone subtraction; cerebral CT angiography (CTA); clip and coil; performance evaluation.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Acquisition of computed tomography angiography (CTA) images by directly subtracting non-contrast CT images without a contrast agent from contrast CT images. Vessel rendering showing segmentation of the subtracted CT images based on the Hounsfield unit (HU) values.
Figure 2
Figure 2
HU values plotted with metallic component, bone, and iodine in the range of 50 keV to 190 keV.
Figure 3
Figure 3
A simplified flowchart of proposed bone subtraction CTA (BS-CTA) method preserving clip and coil components.
Figure 4
Figure 4
Examples of the non-contrast CT (left upper), the CTA (right upper), the BS-CTA (left bottom), and the proposed BS-CTA (right bottom); (a) 56th slice and (b) 59th slice.
Figure 5
Figure 5
The enlarged images of (a) a ROI1 of 56th slice (upper left) and image segmentation in ROI1 (upper middle) represent the complete results of clip segmentation, a reference map (bottom left), a segmentation map (bottom middle) using the proposed method, and an image overlay (bottom right) of both reference and segmentation maps. (b) These are also the resultant images in ROI2 of 59th slice as (a).
Figure 6
Figure 6
Results of 3D rendering of conventional BS-CTA (left) and proposed BS-CTA (right).
Figure 7
Figure 7
Results of non-contrast CT (left), BS-CTA (middle), and the proposed BS-CTA (right); (a) the two-clip case and (b) the coil case.
Figure 7
Figure 7
Results of non-contrast CT (left), BS-CTA (middle), and the proposed BS-CTA (right); (a) the two-clip case and (b) the coil case.
Figure 8
Figure 8
Results of 3D rendering based on BS-CTA and proposed BS-CTA from Figure 7. (a) Insertion of the two clips and (b) the coil components.
Figure 9
Figure 9
Segmentation of both metallic component and bone, which is very close to the target metal, using the proposed method.
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