Image Quality from High-Resolution CT of the Lung: Comparison of Axial Scans and of Sections Reconstructed from Volumetric Data Acquired Using MDCT

OBJECTIVE: Our objective was to compare the image quality of reconstructed thin sections obtained from a 16-MDCT scanner with that of axial high-resolution CT scans of the same patient. SUBJECTS AND METHODS: Fifty consecutive patients referred for CT of the chest underwent 16-MDCT and, subsequently, axial high-resolution CT. The volumetric raw data from the MDCT scans were reconstructed into slices 2-mm thick using a high-spatial-frequency reconstruction algorithm. Two blinded reviewers independently rated the images from both methods for subjective image-quality criteria. The results were tested for statistical significance using Wilcoxon's signed rank test, and p values of less than 0.05 were considered significant. The effective dose for axial high-resolution CT and volumetric MDCT was calculated. RESULTS: Motion artifacts were significantly more common on high-resolution CT scans than on reconstructed thin-section images (p < 0.001). The two methods differed significantly in lung attenuation (p = 0.008), mainly because of the presence of ground-glass opacities. The assessment of ground-glass attenuation was superior on axial high-resolution CT. The effective doses were 3.8 mSv for MDCT and 0.9 mSv for high-resolution CT. CONCLUSION: Reconstructed high-resolution images generated from a single MDCT data acquisition are of comparable quality to images obtained using conventional axial high-resolution CT. However, contiguous MDCT is not recommended for diseases showing predominantly ground-glass patterns, because axial high-resolution CT delineates ground-glass attenuation significantly better.