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State of the Art Cranial Ultrasound Imaging in Neonates
Published on: February 2, 2015
Comparison of Ultrasound and MRI for Measuring Foramen Magnum Diameter in Neonates and Infants: A Preliminary Study
Kojiro Terada1,2, Satoshi Yabusaki3, Kyosuke Ota3
1Division of Pediatrics and Neonatology, Tomakomai City Hospital, Tomakomai, Japan.
Insights
Posterior cervical ultrasound offers a reliable, non-invasive method for assessing foramen magnum diameter in infants, closely matching MRI results. This technique may aid in initial evaluations of craniovertebral junction abnormalities.
Area of Science:
- Neonatal imaging
- Craniovertebral junction abnormalities
- Pediatric radiology
Background:
- The foramen magnum is a critical skull base opening.
- Congenital disorders like achondroplasia can cause stenosis, leading to neurological issues.
- Magnetic resonance imaging (MRI) is used for screening high-risk infants, but ultrasound (US) may offer a non-invasive alternative.
Purpose of the Study:
- To compare the accuracy of ultrasound (US) with magnetic resonance imaging (MRI) for assessing foramen magnum diameter (FMD) in neonates and infants.
- To evaluate US as a potential non-invasive tool for craniovertebral junction assessment.
Main Methods:
- Retrospective review of neonates and infants who underwent MRI.
- Foramen magnum diameter (FMD) measured via posterior cervical ultrasound by a neonatologist.
- Comparison of US and MRI measurements using Bland-Altman analysis.
Main Results:
- No significant difference in FMD measurements between US and MRI (p=0.32).
- Excellent intra-observer reliability for US (ICC=0.95) vs. moderate inter-observer reliability for MRI (ICC=0.65).
- Minimal systematic bias observed in Bland-Altman analysis (mean bias=0.12 mm).
Conclusions:
- Posterior cervical ultrasound provides FMD measurements comparable to MRI in neonates and infants.
- US may serve as a valuable, non-invasive bedside tool for initial assessment and follow-up of craniovertebral junction abnormalities.
- US cannot replace MRI for definitive diagnosis but complements its use.
Background:
The foramen magnum is the largest opening at the skull base. Congenital skeletal disorders such as achondroplasia can cause foramen magnum stenosis, leading to neurological problems. In high-risk infants, repeated magnetic resonance imaging (MRI) is often used to screen for or monitor stenosis. Ultrasound (US), already used for neonatal spinal assessment, may offer a non-invasive method for evaluating the craniovertebral junction. However, to our knowledge, no studies have directly compared foramen magnum assessment between US and MRI.
Methods:
We retrospectively reviewed neonates and infants admitted to the Neonatal Intensive Care Unit (NICU) who underwent MRI between December 2023 and January 2025. Foramen magnum diameter (FMD) was measured in the mid-sagittal view using a posterior cervical US approach by a single neonatologist. US measurements were compared with MRI measurements using Bland-Altman analysis.
Results:
Thirty patients (median corrected age: 39.1 weeks, 17 males) were evaluated. There was no significant difference between FMD measured by ultrasound and MRI (p = 0.32). US measurements demonstrated excellent intra-observer reliability (ICC [1, 3] = 0.95, 95% CI: 0.92-0.98), whereas MRI measurements showed moderate inter-observer reliability (ICC [2, 1] = 0.65, 95% CI: 0.38-0.82). Bland-Altman analysis showed a mean bias of 0.12 mm (95% limits of agreement: -1.2 to +1.4 mm), indicating minimal systematic bias.
Conclusion:
Posterior cervical ultrasound provides FMD measurements in neonates and infants that closely match those obtained with conventional MRI. While US cannot replace MRI for definitive diagnosis, it may serve as a valuable, non-invasive bedside tool for initial assessment and short-term follow-up of craniovertebral junction abnormalities during early infancy.
