[Comparison of various parameters (pitch 1 and 2) in the study of the lung with spiral computerized tomography].
BACKGROUND
In Spiral CT, the pitch is the ratio of the distance the tabletop travels per 360 degrees rotation to nominal slice width, expressed in mm. Performing Spiral CT examinations with pitch 2 allows to reduce examination time, exposure and contrast dose, and X-ray tube overload. We investigated the yield of pitch 2 in lung parenchyma studies, particularly relative to diagnostic image quality.


METHODS
Thirty patients were submitted to Spiral CT with pitch 1 [10 mm slice thickness, 10 mm/s table feed; 10 mm (a') and 5 mm (a") reconstruction index: protocol A] and with pitch 2 [10 mm slice thickness, 20 mm/s table feed; 10 mm (b') and 5 mm (b") reconstruction index: protocol B]. Five expert radiologists evaluated the images separately and blindly, grading noise, bronchial wall resolution and diagnostic yield on a 0-5 point scale. The results of protocol A versus protocol B images were analyzed statistically using the Mann-Whitney U-test.


RESULTS
The mean scores for each parameter ranged 4.13 (.70 standard deviation) for protocol B with 5 mm reconstruction index (b") to 4.81 (.44 standard deviation) for protocol A with 10 mm reconstruction index (a'). These values (max: 5) indicate very positive results on both protocol A and B images. There were no statistically significant interprotocol differences, except for bronchial wall resolution, in favor of protocol A with 5 mm reconstruction index (a") (p = .025), and for diagnostic yield, in favor of protocol A with 10 mm reconstruction index (a') (p = .018).


CONCLUSIONS
Spiral CT with pitch 2 is a reliable tool for lung parenchyma studies which permits to reduce examination time and contrast dose, as well as X-ray tube overload and exposure dose.
Sartoni Galloni
S
S
Servizio di Radiologia I, Ospedale Maggiore, Bologna.
Miceli
M
M
Lipparini
M
M
Burzi
M
M
Gigli
F
F
Rossi
M S
MS
Santoli
G
G
Guidarelli
G
G
D000368:Aged; D005260:Female; D006801:Humans; D008171:Lung Diseases / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D014057:Tomography, X-Ray Computed / Q000379:methods*
Confronto tra diversi parametri (pitch 1 e 2) nello studio del polmone con tomografia computerizzata spirale.