Cerebral Aneurysm Pulsation: Do Iterative Reconstruction Methods Improve Measurement Accuracy In Vivo?

T. Illies; D. Säring; M. Kinoshita; T. Fujinaka; M. Bester; J. Fiehler; N. Tomiyama; Y. Watanabe

doi:10.3174/ajnr.A4000

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Fig 1.
Creation of a line profile across the aneurysms for calculations of edge lengths. The left side shows a right middle cerebral artery aneurysm. A linear region of interest is positioned through the center of the aneurysm. The right side shows a cubic spline function fitted to the measurements for FBP (black) and AIDR (red). Edges are defined as the distance between the 10% and 90% interval of the maximum intra-aneurysmal attenuation (horizontal black lines).
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Fig 2.
Edge lengths compared between AIDR and FBP and edge length compared with intra-aneurysmal attenuation (triangles, left side; dots, right side). On the left side, a Bland-Altman plot shows a small bias of shorter edges in AIDR images. Th right side shows the plot and regression line of edge length and intra-aneurysmal attenuation (P = .45).
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Fig 3.
Bland-Altman plots of absolute volumes and pulsatility. Left side shows a small bias, with a tendency toward smaller absolute volumes in AIDR images. On the right side, there are no differences in pulsatility between the aneurysms in AIDR and FBP images.
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Fig 4.
Aneurysm of the right middle cerebral artery in a 53-year-old patient (patient 1). CT angiography of the 2 reconstruction methods; acquisition parameters are the same. A, Filtered back-projection. B, Image reconstruction with adaptive iterative dose reduction. Note the smoother appearance of the image, consistent with reduced image noise.

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Patient characteristics

Patient No.	Age (yr)	Location (Artery)	Volume (mm3)^{^a}		Diameter (mm)^{^b}
Patient No.	Age (yr)	Location (Artery)	AIDR	FBP	Diameter (mm)^{^b}
1	53	MCA	2336.4	2386.0	16.7
2	66	AcomA	95.1	95.7	6.1
3	55	ICA	69.1	72.9	5.7
4	70	MCA	15.3	15.4	3.9
5	50	ICA	1352.5	1361.7	15.1
6	69	ACA	67.4	67.3	4.3
7	61	ICA	76.7	77.2	5.9
8	76	MCA	58.6	59.2	5.7
9	50	ICA	408.8	407.1	10.7
10	68	MCA	82.2	74.4	7.1

Note:—AcomA indicates anterior communicating artery; ACA, anterior cerebral artery.
↵a For volume measurement, a 3D model of the vasculature was created and the aneurysms were interactively segmented (see “Material and Methods” section).
↵b The aneurysm diameter is the maximum value of the axial, coronal, or sagittal aneurysm diameter.