Volume Measurement of Intracranial Aneurysms from 3D Rotational Angiography: Improvement of Accuracy by Gradient Edge Detection
Javier Oliván Bescósa,
Marjan J. Slobb,
Cornelis H. Slumpa,
Menno Sluzewskib and
Willem Jan van Rooijb
a Department of Electrical Engineering, Mathematics and Computer Sciences, Technical University Twente, Enschede, the Netherlands
b Department of Radiology, St. Elisabeth Ziekenhuis, Tilburg, the Netherlands
View larger version (35K):
[in a new window]
|
FIG 1. 3D angiographic image of a posterior communicating artery aneurysm in 3 different manual threshold settings. All 3 images are visually acceptable to delineate vessel and aneurysm anatomy.
A, Low-threshold setting: not all small vessels are visible. After segmentation of the aneurysm, the calculated volume is 179 mm3 (D).
B, Intermediate-threshold setting: better visualization of small vessels. After segmentation of the aneurysm, the calculated volume is 207 mm3 (E).
C, High-threshold setting: exaggerated visibility of small vessels. After segmentation of the aneurysm, the calculated volume is 266 mm3 (F).
| |
View larger version (122K):
[in a new window]
|
FIG 2. Two-dimensional illustration in a cut plane of the 3D dataset. The blue lines represent the contours in the cut plane of a blood vessel (ellipsoid) and an aneurysm (circle).
A, -B, Manual thresholding: different threshold levels change the contours of the vessel and the aneurysm.
Gradient-edge detection: voxels with high gradient values are white and voxels with low gradient values are black. In homogeneous parts of the volume, some gradient differences are present, caused by image noise (C). After the small gradient differences are filtered, the contours are unchanged (D).
| |
View larger version (76K):
[in a new window]
|
FIG 3. A, Four aneurysm phantoms on a parent artery in different shapes and sizes in Perspex.
B, Radiograph of aneurysm phantoms filled with contrast material in a human skull placed in a water-filled bucket. Injection lines filled with contrast material simulate blood vessels.
| |
View larger version (9K):
[in a new window]
|
FIG 4. Graphic display of errors in volume measurement of 13 aneurysm phantoms with the manual threshold method and the gradient edge detection method.
| |
View larger version (30K):
[in a new window]
|
FIG 5. Mountain plot of percentile for each ranked difference from the phantom volumes for the gradient edge detection method and the manual threshold method. Dotted line indicates manual threshold method; solid line, the gradient edge detection method.
| |
