Use of the vertebrae and iliac bone as references for localizing the appendix vermiformis in computed tomography

Figure 1 Determining the localization of the highest point of the appendix using the vertebrae as a reference. A: The highest point of the appendix vermiformis is detected (orange arrow) on axial images; B: Subsequently, the highest point is verified on coronal images (orange arrow); C: The highest point (orange arrow) is marked on axial images with reference lines; D and E: The vertebral level of the marked point is determined using coronal and sagittal thick multiplanar reconstruction images, respectively, with bone window settings. Subsequently, the same assessment is conducted to identify the lowest point of the appendix. L: Lumbar vertebra; S: Sacral vertebra.

Figure 2 Determining the localization of the highest point of the appendix using the right iliac bone as a reference. A: The highest point of the appendix vermiformis is detected (orange arrow) on axial images; B: The highest point is verified on coronal images (orange arrow); C: The highest point (orange arrow) is marked on axial images with reference lines; D: The distance between this designated point and the highest point of the right iliac bone is measured using the thick coronal multiplanar reconstruction images in the bone window. The distance is measured from the point where the horizontal line intersects with the highest point of the right iliac bone. If the designated point is situated above the highest point of the right iliac bone, it is denoted as positive (+), and if it is positioned below, it is denoted as negative (−), with measurements in mm. In this patient, the highest point of the appendix was localized at −33 mm relative to the highest point of the right iliac bone. Subsequently, using the same technique, the origin and lowest points of the appendix vermiformis were determined. L: Lumbar vertebra; S: Sacral vertebra.