Frontal Sinus Morphological Analysis

The 3D frontal sinus models, obtained from CT images, were analyzed to measure their maximum dimensions. The frontal sinus volume was defined as the total space of the air-filled cavity in the frontal bone, and volume-rendering images were used to automatically calculate the frontal sinus volume (Figure 2). The maximum width was defined as the distance between the right- and left-side points of the frontal sinus. The maximum height was defined as the distance between the baseline and the highest points. The maximum depth was measured as the distance between the most prominent front and rear points of the frontal sinus. Morphological characteristics were determined by appearance, whether bilateral or unilateral, symmetrical or asymmetrical, and fusion or separation. According to previous studies [17 (link),18 (link)], the frontal sinus shape can be classified into three types: fan-shaped, quadrangular, and irregular.