Abstract:

BACKGROUND: The display rate of pulmonary artery and the incidence of artifact by CT pulmonary angiography (CTPA) play an important role in the evaluation of diagnostic accuracy.
OBJECTIVE: To evaluate the effect of different thickness on the 128-slice spiral CT display rate of pulmonary artery and the incidence rate of artifact.
METHODS: Patients with suspected acute pulmonary embolism were examined by CTPA, and images were divided into 4 groups according to different thickness: 0.6, 1.0, 3.0 and 5.0 mm. Display clarity of pulmonary embolism arteries of the images of 4 groups was compared to evaluate the continuous level of pulmonary artery branches and the incidence rate of artifact.
RESULTS AND CONCLUSION: The main pulmonary artery and lobe pulmonary artery of two lungs showed no significant difference among the 4 groups; segmental and sub-segmental pulmonary artery showed 0.6 mm and 1.0 mm slice thickness were better than 3.0 mm and 5.0 mm thickness groups (P < 0.001); for the 6th pulmonary artery, 4 groups showed significant differences (P < 0.001), and the display rate of 0.6 mm was the best. The ability that 1.0 mm slice thickness images showed sub-segmental pulmonary artery branch level and above was similar to the 0.6 mm, and better than 3.0 mm and 5.0 mm groups; 3.0 mm and 5.0 mm slice thickness groups showed continuous pulmonary artery  all branches lower than 0.6 mm and 1.0 mm slice thickness groups. Partial volume artifacts of 39 cases with negative were 2 cases from 0.6 mm group, 5 from 1.0 mm group, 11 from 3.0 mm group, 17 from 5.0 mm group, showing significant differences among 4 groups (P < 0.001). In CTPA examination, slice thickness at 3.0 mm or less can observe sub-segmental pulmonary artery more accurately, while 0.6 mm slice thickness can reduce the incidence of partial volume artifacts and improve images quality of CTPA.