BACKGROUND AND PURPOSE: The inner ear is characterized by fine and intricate anatomy. Due to magnetic inhomogeneity, inner ear imaging has not benefited much from ultra-high-field-strength MRI. 5T may provide an alternative for inner ear imaging. This study aimed to compare image quality and visibility of specific structures between 5T and 3T MRI. MATERIALS AND METHODS: Consecutive healthy volunteers, who underwent heavily T2-weighted imaging at 3T and 5T within 1 week, were prospectively enrolled between September and October 2025. Image quality was rated using the Likert scale for overall image and specifically the inner ear and nerve apparatus. SNR, contrast-to-noise ratio (CNR), and image sharpness were quantitated. Wilcoxon signed-rank tests or paired t tests were used for interfield comparison. Interobserver and interfield agreements were assessed. RESULTS: A total of 22 participants (median age: 40.50 [30.00?49.00] years; 10 women; 44 ears) were included. There was no observed difference in overall image quality between 5T and 3T across 3 readers (average median scores: both 4.67; P > .999). Compared with 3T, 5T demonstrated a superior visibility for the posterior ampullary nerve, superior vestibular nerve, cochlear nerve (CN), and cochlear aperture segment of CN, as well as foramen singulare and osseous spiral lamina. The visibility score of the inferior vestibular nerve was marginally higher at 5T than that at 3T for readers (P = .054?.094). No differences in visualizing evaluated membranous labyrinth structures between 2 field strengths were observed. SNR, CNR, and image sharpness were higher at 5T than at 3T. CONCLUSIONS: Compared with 3T, a 3D heavily T2-weighted sequence at 5T improved the detectability of nerves significantly, particularly segments coursing through bony ducts, as well as the foramen singulare and osseous spiral lamina.
BACKGROUND AND PURPOSE: The STIR-FSE pulse sequence is commonly used for 3D MR neurography (MRN) of the brachial plexus (BP) due to its low B-0 susceptibility and robust fat suppression. An alternative 3D acquisition is a multiecho in steady-state acquisition (MENSA-NERVE) sequence that typically provides more robust vascular suppression but poorer fat suppression due to its use of a water excitation pulse. MATERIALS AND METHODS: A total of 50 subjects (24 women, median age [range]: 34 years [14-73 years]) underwent unilateral BP MRN at 3T where noncontrast STIR-FSE and MENSA-NERVE were sequentially acquired and retrospectively analyzed. Sequences were assessed by 2 radiologists for vascular suppression, fat suppression, and visualization of the BP nerve roots, trunks, and cords, as well as of the suprascapular nerve and axillary nerve. Pooled measurements were analyzed using the Wilcoxon signed-rank test, and agreement proportion was used to assess interrater/intersequence diagnostic agreement. RESULTS: MENSA-NERVE outperformed STIR-FSE for vascular suppression (P < .001). Fat suppression assessments favored STIR-FSE over MENSA-NERVE (P = .05 to P < .001), with incomplete fat suppression obscuring nerve visualization in MENSA-NERVE, primarily observed only at the lung apex. MENSA-NERVE provided superior visualization of the suprascapular and axillary nerves (P = .004 to P < .001). Interrater agreement of visualized pathology was good to excellent (agreement = 0.74-0.92) for both sequences. Intersequence agreement was also excellent (agreement = 0.80-0.88). CONCLUSIONS: MENSA-NERVE provided superior vascular suppression and nerve conspicuity compared with noncontrast STIR-FSE and with less robust fat suppression at the neck-shoulder junction and lung apex.
BACKGROUND AND PURPOSE: The posterior cranial fossa (PCF) houses structures that are critical for neurological development and the integrated functioning of the central nervous system. Despite their clinical relevance, age and sex-specific reference biometric data in pediatrics remain limited. Aim of this study was to perform a Biometric Investigation Of Morphology and Anatomy in the Pediatric PCF (BIOMAP-PCF), to provide age- and sex-specific reference curves of these structures in a large pediatric population. MATERIALS AND METHODS: In this retrospective two-center study, 3D T1-weighted images of 1054 pediatric subjects from 0 to 18 years were analyzed (9.0±5.0 years, M/F=508/546). Different linear and cross-sectional area measurements of PCF structures were obtained, and age- and sex-specific reference intervals for each variable were estimated using the Royston and Wright method. To better evaluate the pattern of age-dependent changes between posterior cranial fossa structures, selected ratios were calculated. RESULTS: Reference values (3rd, median and 97th percentile) were obtained for each parameter. All measures showed nonlinear growth, with rapid changes in early childhood followed by progressive slowing. Ratios showed stable anteroposterior brainstem proportions across age, while the pons-to-midbrain craniocaudal ratio showed a mild age-related increase. Intra- and interobserver agreement was excellent (ICC>0.90) for all parameters, with the only exception of one measure showing an ICC=0.89. CONCLUSIONS: We provide highly reproducible age- and sex-specific reference curves for PCF structures in pediatric populations. Linear and cross-sectional area measurements, together with brainstem ratios, provide a reproducible, clinically applicable framework for quantitative assessment of PCF development in children.
