The effect of head coil configuration and channel count on the quality of double inversion recovery (DIR) MRI images.

Abstract

Background: Double inversion recovery (DIR) MRI provides high sensitivity for detecting white matter abnormalities but suffers from reduced signal-to-noise ratio (SNR) due to simultaneous suppression of multiple tissue signals. Head-coil configuration and channel count may influence the resulting image quality.

Methods: Seventeen healthy subjects underwent DIR imaging on a 3-T MRI system using both 64-channel and 20-channel head/neck coils. Quantitative image quality was assessed using SNR and contrast-to-noise ratio (CNR) measurements across multiple brain regions, with comparisons performed using paired t-tests. Structural Similarity Index Measure (SSIM) was additionally computed between registered 64-channel and 20-channel DIR images to quantify inter-coil structural image similarity. Qualitative image quality was evaluated by three experienced neuroradiologists using a 5-point rating scale for contrast, spatial resolution, and noise; inter-rater agreement was assessed using Kendall's coefficient of concordance (Kendall's W).

Results: Quantitative analysis demonstrated significantly higher SNR and CNR values for the 64-channel coil compared with the 20-channel coil across all assessed regions (p < 0.0001). Qualitative evaluation showed that images acquired with the 64-channel coil received marginally higher mean scores for contrast, spatial resolution, and noise from all raters; inter-rater agreement was moderate-to-strong across all domains (Kendall's W = 0.33-0.89).

Conclusion: At 3 T, the use of a 64-channel head/neck coil provides significant quantitative improvements in DIR image quality compared with a 20-channel coil, with small but consistent advantages also observed in qualitative assessments. These findings support the use of higher-channel-count coils to mitigate SNR limitations inherent to DIR imaging. However, qualitative differences between coil configurations were modest and inter-rater agreement was moderate-to-strong by Kendall's W (W = 0.33-0.89). The clinical benefit of the 64-channel coil in pathological conditions such as multiple sclerosis or cortical dysplasia requires further investigation in patient-based studies.