Comparing accuracy of cochlear measurements on magnetic resonance imaging and computed tomography: A step towards radiation-free cochlear implantation

Objective

Computed Tomography (CT) and Magnetic Resonance Imaging (MRI) are commonly employed in pre-operative evaluation for cochlear implant surgery. However, with a decrease in the age of implantation, even minor radiation exposure can cause detrimental effects on children over their lifetime. The current study compares different cochlear measurements from CT and MRI scans and evaluates the feasibility of using only an MRI scan for radiological evaluation before cochlear implantation.

Methods

A longitudinal observational study was conducted on 94 ears/47 children, employing CT and MRI scans. The CT and MRI scan measurements include, A value, B value, Cochlear duct length (CDL), two-turn cochlear length, alpha and beta angles to look for cochlear orientation. Cochlear nerve diameter was measured using MRI. The values were compared.

Results

The mean difference between measurements from CT and MRI scans for A value, B value, CDL, and two-turn cochlear length values was 0.567 ± 0.413 mm, 0.406 ± 0.368 mm, 2.365 ± 1.675 mm, and 2.063 ± 1.477 mm respectively without any significant difference. The alpha and beta angle measures were comparable, with no statistically significant difference.

Conclusion

The study suggests that MRI scans can be the only radiological investigation needed with no radiation risk and reduces the cost of cochlear implant program in the paediatric population. There is no significant difference between the measurements obtained from CT and MRI scans. However, observed discrepancies in cochlear measurements across different populations require regionally or race-specific standardized values to ensure accurate diagnosis and precision in cochlear implant surgery. This aspect must be addressed to ensure positive outcomes for patients.