[B-modes ultrasonic diagnosis of the maxillary sinus]

As a routine preoperative evaluation for chronic sinusitis and postoperative maxillary cyst (mucocele and pyocele), CT scans and B-mode ultrasonic diagnosis including three methods, linear, sector, and convex scans, were performed. By chronic sinusitis, 112 sides by linear scans, 43 sides by sector scans, and 29 sides by convex scans were included in the study. By the postoperative cyst, 43 sides by linear scans, 24 sides by sector scans, and 12 sides by convex scans were included. The positive diagnostic finding by ultrasonography is defined as the depicted echo of the posterior wall. In chronic sinusitis, positive diagnostic rates were as follows: linear scans, 73.2%, sector scans, 88.2%, and convex scans, 77.8%. As for the scan planes, horizontal plane yielded more positive than sagittal one. In postoperative cyst similarly, linear, 86.0%, sector, 95.8%, and convex, 83.3%. Horizontal more positive than sagittal also. The negative findings were caused, in chronic sinusitis, by attenuation by the air in the sinus, thick anterior wall, and artifacts. In postoperative cysts, the negative findings were caused by specific location of the cysts (lateral or posterior). Our results recommend the use of sector scan because of its easy manipulation and higher positive diagnostic rates due to the radial beam conforming to the curvature of the posterior wall. Especially, the sector scan was higher diagnostic rate than linear scan, because the sector scan transmitted radial beam, and received its reflective wave easily from a curved posterior wall of the maxillary sinus. The sector scan, its manipulation is easy, and its diagnostic rate is higher than any other scans.