AJR:193, November 2009
Carlos A. Rojas, Alex Hayes, John Christopher Bertozzi, Chantal Guidi, Carlos Rodrigo Martinez
OBJECTIVE. We aimed to establish normal values on MDCT images for the atlantoaxi_al relationships including the atlantoaxial interval and lateral atlantodens interval (ADI) that could be used to detect atlantoaxial ligamentous injuries in adults and children.
MATERIALS AND METHODS. One hundred seventy–eight healthy adult patients be_tween 20 and 40 years old and 112 pediatric patients between 2 months and 10 years old under_went cervical spine MDCT with multiplanar reconstructions. The width of the joint space be_tween the lateral mass of CI and the lateral mass of C2 was measured at three equidistant points on both the left and right sides on coronal reformatted images to determine the atlantoaxial in_terval. The distance between the lateral surface of the dens and the medial surface of the lateral mass of CI was measured in the coronal plane to determine the lateral ADI bilaterally.
RESULTS. The upper limit of the normal range of values for the atlantoaxial interval in adults was 3.34 mm on the right and 3.39 mm on the left. The upper limit of normal for the lateral ADI was 4.67 mm on the right and 5.6 mm on the left. More than 95% of the pediat_ric population was found to have an atlantoaxial interval of less than 3.9 mm on either side, a right lateral ADI of less than 7.4 mm, and a left lateral ADI of less than 8.0 mm.
CONCLUSION. We propose that the obtained normal values be considered as the up_per limits of the normal range for the atlantoaxial interval in adult and pediatric populations on MDCT images.