[Application of spiral CT and post-image processing technique in the staging of central lung cancer]

To assess image processing techniques including multiplanar reconstruction (MPR), volume rendering technique (VRT) and spiral CT angiography (SCTA) in the staging of central lung cancer (CLC), with transverse image, pathology and findings on the operation table as comparison.

Forty-six suspected CLC received spiral CT examination, on basis of prospective randomization, by a Picker 6 000 scanner. Contrast medium was injected at a rate of 4 ml/s with a power injector. The study volume done in a single breath-hold was from the aortic arch to the inferior pulmonary veins, using 3-mm collimation, pitch of 1.0 and reconstruction at 1-mm interval. Six patients were excluded after operation. Transverse CT scans, MPR and VR images were studied in a double-blind way by 3 experienced radiologists, with the findings compared with the surgical and pathological results.

Post-processing image was more accurate than transverse CT scan in T categories (95.7% vs 82.6%), chi(2) = 4.039, P = 0.044. Four cases of N3 category on transverse CT scans were not proved by surgical or pathological results. The sensitivity, specificity and accuracy rates in N categories were 75.0% (12/16), 26.9% (7/26) and 45.2% (19/42). The accuracy rate of staging was 58.7% (27/46) by transverse CT scans and 67.4% (31/46) by post-processing images (chi(2) = 0.746, P = 0.338).

Post-processing image is more accurate than transverse image in T categorizing.