Craniofacial measurements using zero echo time magnetic resonance imaging

Radiation exposure remains a major concern in dentomaxillofacial imaging, especially for children and young adults who require repeated examinations. A precise, non-ionizing alternative for craniofacial measurement would have significant implications for clinical practice. Computed tomography (CT) and cephalometry are widely used but expose patients to ionizing radiation. Zero Echo Time Magnetic Resonance Imaging (ZTE-MRI) enables visualization of short-T2 tissues, including cortical bone, without radiation by minimizing TE towards zero; however, clinical head-and-neck use has been limited. The goal of the present study was to investigate the possibility of performing precise 3D measurements of the craniofacial regions using ZTE-MRI.

Twenty-nine participants (mean age 32.14 ± 17.09 years; 23 female, 6 male) underwent MDCT and ZTE-MRI. Standard cephalometric landmarks were identified, yielding 27 linear and 21 angular variables. For each variable, linear regression analysis was performed for the results on MDCT (Multi-Detector CT) images and ZTE-MRI.

Nineteen linear and eight angular variables had regression coefficients between 0.9 and 1.1, and 28 of the linear and 16 of the angular variables had R2 values of 0.81 or higher. Twenty-five linear and 16 angular variables showed Cohen's effect sizes within the ±0.8 range.

Variables derived from skeletal reference points showed clinically acceptable results, indicating that ZTE-MRI is useful for these measurements. In contrast, variables involving dental reference points demonstrated lower agreement, making accurate measurement in these regions difficult.

To our knowledge, this study is the first to show that ZTE-MRI allows feasible linear and angular craniofacial measurements used in dental practice and demonstrates good agreement with MDCT for major skeletal landmarks. These findings support its potential future clinical applicability for radiation-free bone assessment; however, further research is warranted to establish its performance across all measurements.