Performance of a single lookup table (LUT) for displaying chest CT images

To evaluate the ability to view mediastinal and lung information on one window setting by processing images with a bilinear lookup table (LUT).

Chest computed tomography (CT) studies were obtained from 32 consecutive adult patient studies, which included 7 iodine contrast studies. From each CT examination, four sections were selected containing the suprasternal notch, carina, right inferior pulmonary vein, and the dome of the lower hemidiaphragm. Each image was processed with a bilinear LUT in addition to the lung setting (window width 1500 and window level -500) and mediastinal setting (window width 450 and window level 50) normally used. Seven radiologists compared the quality of the bilinear LUT with the corresponding lung and mediastinum display settings. A five-point scale was used to assess image quality, with a score of 5 being equivalent to the corresponding lung (or mediastinum) display, 3 being acceptable, and 1 being unacceptable.

The average score of the bilinear LUT for all images and readers was 3.90 +/- 0.93 for lung information and 3.17 +/- 1.00 for mediastinum information. Use of the bilinear LUT resulted in unacceptable images in 0.3% cases for lung information and 5.9% for mediastinum information. Chest CT images that contained iodinated contrast resulted in a higher score than those obtained without contrast, but these differences did not achieve statistical significance.

Use of a bilinear LUT has the potential to significantly improve operational efficiency with acceptable image quality for most chest CT images.