Article Figures & Data
Figures
- Fig 1.
Example x-ray image acquired by the flat panel angiographic C-arm system before (left) and after (right) removal and replacement of the high-absorption areas caused by coils and dental fillings (arrows).
- Fig 2.
Coronal (top row) and axial sections (bottom row) of conebeam CT data of a patient acquired before coil embolization (column A), after coil embolization without MAR (column B), and after coil embolization with MAR (column C).
- Fig 3.
Corresponding axial sections of VasoCT data acquired after stent placement (A, stent indicated by asterisk) and after coil embolization (B and C). Streak artifacts generated by the coil mass visible in VasoCT data without MAR (B) are severely reduced with MAR (C). Because of the replacement of absent data in the raw projections, subtle new artifacts appear in VasoCT with MAR (C, arrows). Intensity profiles (yellow lines) were generated for all 3 images by use of the same physical coordinates (white lines). The intensity scale of the profile analysis is given on the left-hand side of the figure. Profile plots show that severe fluctuations outside the coil mass are reduced by MAR and the resulting profile in C is similar to the profile in A.
- Fig 4.
Conebeam CT data without (A) and with (B) MAR demonstrating the reduction of coil mass artifacts and the appearance of subtle streak caused by the algorithm, which is specifically well visualized in the indicated circular region of interest.
- Fig 5.
Illustrative case 1. DSA at 6-month follow-up shows no recanalization of the embolized posterior communicating artery aneurysm (A). Streak artifacts caused by the coil mass (arrows) in maximum intensity projection of VasoCT data without MAR (B) partially obscures visualization of stent and host artery. After MAR (C), streak artifacts in VasoCT data were removed, revealing the stent and host artery.
- Fig 6.
Illustrative case 2. Immediate DSA (A) maximum intensity projection of VasoCT data without MAR (B) and with MAR (C) of stent-assisted coil embolized aneurysm at the right A1 segment. Visibility is significantly affected by streak artifacts caused by the coil mass (arrows) and contralateral clip in VasoCT without MAR. With MAR, stent apposition to the vascular wall is fully appreciated.
- Fig 7.
Illustrative case 3. DSA (A), maximum intensity projections of VasoCT without (B), and with MAR (C) acquired immediately after stent-assisted coil (arrows) embolization procedure. Streak artifacts partially obscuring the host artery and side branches are removed by the MAR method.
- Fig 8.
Illustrative case 4. Immediate DSA (A), VasoCT without MAR (B), and VasoCT with MAR (C) after stent-assisted coiling of an unruptured middle cerebral artery aneurysm. Although streak artifacts caused by the coil mass (arrows) are significantly reduced, a small amount of streak remains after application of MAR.
Tables
Results of the observer study rating the visibility without and with MAR
Without MAR κ With MAR κ Overall Agreement, % Score 1 Agreement, % Score ≥2 Agreement, % Overall Agreement, % Score 1 Agreement, % Score ≥2 Agreement, % Stent visibility P < .05 OR = 7.8 77 56 12 0.66 76 24 40 0.64 CI = 1.6–38.8 Vessel visibility P < .05 OR = 8.7 76 52 12 0.64 72 20 40 0.58 CI = 1.7–45.2 Relationship P < .05 OR = 9.0 81 60 12 0.72 70 20 36 0.56 CI = 1.7–47.0 Overall Agreement, % Yes Agreement, % No Agreement, % κ Overall Agreement, % Yes Agreement, % No Agreement, % κ Obscuring beyond coil mass? (P < .0001 OR = 224.0 73 56 4 0.47 78 4 64 0.57 CI = 12.8–3926.0) Overall Agreement, % Without MAR Agreement, % With MAR Agreement, % κ Overall best visibility 94 0 92 0.89 Note:—The rows “stent visibility,” “vessel visibility,” and “relationship” show the summarized results to the 3-point scale questions. Given are the percent overall agreement (ie, the number of cases that all reviewers agreed in total, calculated using the Fleiss method), the percent agreement for a score 1 (ie, the number of cases all reviewers agreed on giving a score of 1), and the percent agreement for a score ≥2 (ie, the number of cases all reviewers agreed on giving a score of 2 or 3). Similarly, agreements for the binary questions are indicated. For each observer question, the κ values, P value, odds ratio (OR), and 95% confidence intervals (CI) are given when applicable. OR represents the improvement of classification of 1 to ≥2 with MAR.
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