Arch Hellen Med, 26(3), May-June 2009, 384-389
Elimination of artifacts through spatial reconstitution in thoracic aorta imaging examination
E. LAVDAS, V. ROKA, G. PROTOGEROU, M. VLYCHOU, I.V. FEZOULIDIS
OBJECTIVE The purpose of this study was to record streak artifacts appearing in chest imaging examinations and also to evaluate the possibility of eliminating or minimizing them through spatial reconstruction, for better visualization of the thoracic aorta. Streak artifacts are very common as examinations are performed with the use of IV contrast medium injection in high concentrations (350-370 mgI/mL), at injection rates of higher than 4 mL/sec and a fast scan time of the area of interest.
METHOD A spiral CT (Philips 5000 SR) was used, with a scan time of 1.5 seconds per rotation and 40 chest examinations were included in the study, which were selected randomly during the program, whenever the images contained artifacts that could simulate pathology. An experienced radiologist selected the cases, and an experienced radiographer applied the spatial resolution. Two experienced radiologists performed quality evaluation in a double-blind study and four different image categories were created, according to the improvement of image quality.
RESULTS In the first category (no improvement) were classified 17.5% of the cases namely none of the processed images improved with the spatial reconstruction method (less than 10% compared to the initial images). In the second category (slight improvement) were classified 35% of the cases. The scoring rate was better by a percentage of 11-35% compared to the initial images. In the third category (substantial improvement) were classified 27.5% of the cases. The scoring rate was better by a percentage of 36-70% compared to the initial images. In the fourth category (significant improvement) were classified a 25% of the cases. The scoring rate was better by a percentage of 71-100% compared to the initial images.
CONCLUSIONS Spatial reconstruction, when applied to chest CT examinations, improves the quality of the image and contributes to the derivation of more accurate conclusions. This process for the correction of streak artifacts is suggested not only for safety reasons but also because it is difficult for an examination to be repeated on the same day due to the maximum dose of the contrast medium received.
Key words: Motion artifacts, Segmental reconstruction, Streak artifacts.