[Diagnosis of acute lung embolism with spiral CT and 3D reconstruction. Development of an animal model and technical probe in an ex-vivo experiment].
OBJECTIVE
To develop a model for simulation the CT morphologic situation of acute pulmonary embolism, to evaluate the accuracy of spiral CT and 3D reconstruction in the detection of artificial emboli and to investigate the influence of the orientation of emboli depending on z-axis orientation.


METHODS
Standardized artificial emboli made of wax and of defined size and shape were positioned into the pulmonary arteries of porcine lungs. Castings of the embolized pulmonary arterial trees were made by injection of a special opaque resin. After performance of spiral CT the data sets of the emboli and the pulmonary arteries were post-processed. The 3D segmentations were compared with the anatomic preparation to evaluate the accuracy of spiral CT/3D reconstruction-technique. Technical specimens simulating CT-morphology of acute embolized vessels underwent spiral CT in six different positions with respect to the z-axis. The CT data were reconstructed using a standardized and a contrastadapted method with interactive correction. The 3D emboli were analysed under qualitative aspects, and measurements of their extent were done.


RESULTS
In nearly 91%, there was complete agreement between CT and the corresponding findings at the anatomical preparation. Measurements of the 3D reconstructed technical specimens showed discrepancies of shape and size in dependence of the size of the original preparation, orientation and reconstruction technique. Overestimation up to 4 mm and underestimation to 2.2 mm were observed. Measurements of preparations with heights from 14 to 26 mm showed variances of +/- 1.5 mm (approximately 6-11%).


CONCLUSIONS
The presented models are suitable to simulate CT morphology of acute pulmonary embolism under ex-vivo conditions. Accuracy in the detection of artificial emboli using spiral CT/3D reconstruction is affected by localization, size and orientation of the emboli and the reconstruction technique.
Ries
B G
BG
Klinik und Poliklinik für Radiologie der Johannes-Gutenberg-Universität Mainz. ries@rad.rwth-aachen.de
Kauczor
H U
HU
Konerding
M A
MA
Thelen
M
M
D000208:Acute Disease; D000818:Animals; D006801:Humans; D007089:Image Enhancement; D007091:Image Processing, Computer-Assisted; D021621:Imaging, Three-Dimensional; D019047:Phantoms, Imaging; D011651:Pulmonary Artery / Q000000981:diagnostic imaging; D011655:Pulmonary Embolism / Q000000981:diagnostic imaging*; D013552:Swine; D014057:Tomography, X-Ray Computed / Q000379:methods*