[Simple evaluation of CT findings in the paranasal sinuses for chronic sinusitis]

The CT scores and scoring for improvement based on them, which we proposed previously, is a simple and highly reproducible method of evaluation of sinus units before and after an operation for chronic sinusitis. We compared this evaluation method with the results of quantitative assay and showed its advantages and disadvantages. The subjects were 258 sinuses in patients who underwent endonasal sinus surgery (ESS) in the department of otolaryngology, Kyoto Prefectural University of Medicine Hospital from April 1996 to April 1997. The subjects were evaluated according to the following 4 grades negligible shadow in the paranasal sinus CT scored 0, less than 50% shadow scored 1, more than 50% of shadow scored 2, and mostly filled with shadow scored 3. Furthermore, the preoperative and postoperative CT scores were compared and the rate of improvement was rated in the following 3 grades: score 0 for unchanged or aggravated subjects, score 1 for subjects showing improved CT score by 1 grade, and score 2 for those showing improved CT score by 2 grades or a postoperative CT score of 0. Quantitative image analysis was input into a personal computer and the ratio occupied by the shadow was calculated, as the shadow ratio. While some discrepancies were seen in parts in the comparison of the quantitative image analysis and CT scores as the former captures minute shadows, a positive correlation was obtained overall. Attention is needed to accurately evaluate small paranasal sinuses such as the frontal sinus, and small amounts of shadow, which are areas where errors may occur. A satisfactory correlation was obtained between the score for the improvement rate and the difference in the shadow ratios before and after surgery. The CT scores and the scores for the improvement rate showed no difference from the results of other evaluation methods reported in the past, and evaluation of similar precision was possible. It was thought that this simple evaluation method of CT findings in the paranasal sinuses, which we examined in the present study, was quite useful as a simple stage-classification method that could be utilized in everyday practice considering its facility, reproducibility and satisfactory precision.