ULTRASOUND IN THE ASSESSMENT OF CRANIAL BONE THICKNESS

Preoperative knowledge of skull thickness before harvesting cranial bo ne grafts would be ideal to help minimize intracranial complications. Previous research has demonstrated regional variations in calvaria; ho wever, accurate preoperative and intraoperative methods of skull thick ness measurement are not available. The aim of this research represent s the first attempt to examine the reliability of ultrasound to determ ine cranial bone thickness. Four previously studied calvarial sites we re marked in 10 adult male cadaveric skulls. The individual points wer e insonified using an A-mode ultrasonic transducer operating in pulse- echo mode. The times of flight of the waves propagating in the bone sa mples were compared with caliper measurements. The mean difference in cranial bone thickness was 0.16 mm, with a standard deviation of 0.09 mm. Student's t-test failed to reveal any statistically significant di fferences between caliper and ultrasonic measurements (p = 0.569) and Pearson's correlation coefficient supported an extremely strong and po sitive relationship between the two modalities (r > 0.992). Multiple l inear regression models predicted that calvarial thickness could be ac curately predicted by ultrasound without consideration of cadaveric sp ecimen or sampling point location (R-2 = 0.988). The convergent values between ultrasonic and caliper measurements suggest that this modalit y can accurately and reliably determine skull thickness. A-mode ultras ound can have significant implications in guiding the harvest of in si tu split cranial bone grafts, the placement of osseointegrated implant s, skull anthropometrics, and related craniomaxillofacial applications .