BACKGROUND: The stria of Gennari (SoG) is a densely myelinated band within layer IVb of the primary visual cortex (V1) and represents the only cortical laminar structure visible macroscopically in vivo. Ultrahigh-field MRI may improve its detection and conspicuity.

PURPOSE: To quantitatively and qualitatively compare the in vivo appearance of the SoG at 3 versus 7 T using matched high-resolution T2-weighted fast spin-echo MRI.

STUDY TYPE: Prospective.

POPULATION: A total of 12 subjects (6 female, 6 male; median age, 17 years; range, 15-24 years) with pediatric-onset epilepsy.

FIELD STRENGTH/SEQUENCE: 3 and 7 T MRI, T2-weighted fast spin-echo, acquired within 1 month of each other.

ASSESSMENT: Cortical line profiles per subject were extracted orthogonally to the calcarine sulcus in V1. Quantitative metrics included peak-valley distance, Δ-signal (peak-valley difference), and contrast ratio (CR). Two blinded neuroradiologists and a radiologist independently rated SoG conspicuity using a 5-point Likert scale.

STATISTICAL TESTS: McNemar's test compared detection rates; paired t-tests or Wilcoxon signed-rank tests compared quantitative metrics; reader preferences were analyzed using Wilcoxon tests; inter-reader agreement was assessed using weighted Cohen's κ. No multiple-comparison correction was applied (α = 0.05).

RESULTS: SoG-consistent valleys were detected in 31% of profiles at 3 T and 65% at 7 T, significantly. Peak-valley distance remained stable across field strengths (0.45 ± 0.06 depth units; p = 0.37). Mean Δ-signal (33.5 vs. 36.1; p = 0.81) and contrast ratio (0.013 vs. 0.000; p = 0.54) did not differ significantly. Both readers demonstrated a strong preference for 7 T images (pseudo-median +1 to +1.5; significant), with fair inter-reader agreement (κ = 0.36).

DATA CONCLUSION: The SoG can be visualized in vivo at both 3 and 7 T, with higher detection frequency and greater subjective conspicuity at 7 T. Quantitative laminar metrics remained stable across field strengths, suggesting that improved detectability at 7 T likely reflects enhanced spatial definition rather than measurable changes in signal contrast.

TECHNICAL EFFICACY: Stage 2.