Optimizing T2* imaging for adolescent and young adult patients at 7 T.

Background: T2*-weighted imaging at 7 T offers detailed visualization of brain structures, but image quality and artifacts depend on echo time (TE) adjustments. Optimizing TE is crucial for tissue contrast and artifact minimization.

Objective: To evaluate the impact of TE on tissue contrast and image quality in T2*-weighted sequences at 7 T in adolescents and young adults.

Materials and methods: Ten adolescent and young adult patients underwent 7-T MRI with multi-echo T2*-weighted sequences. Six TEs (8.1 ms to 36 ms) were acquired. Signal contrast ratios (CR) for seven brain regions-caudate nuclei, corpus callosum genu, frontal cortex, cortical veins, globi pallidi, medullary veins, and left optic radiation-were analyzed. Two blinded neuroradiologists assessed image quality and artifact severity using a 4-point Likert scale (IQS). Statistical trends were analyzed using the Jonckheere-Terpstra test. A P-value < 0.05 was considered statistically significant.

Results: The study cohort consisted of 4 male and 6 females; the median age of the patients was 16 years (range 15-23 years). CR increased significantly with higher TEs for most regions except the caudate, where CR decreased (P < 0.05). Longer TEs led to greater artifact severity in the brainstem, temporal, occipital, and frontal lobes (P < 0.02), but not in parietal lobes (P > 0.05). Kappa agreement for IQS was 0.76.

Conclusion: TE significantly affects contrast and artifacts in 7-T T2*-weighted imaging. TEs between 20 and 30 ms offer the best balance between tissue contrast and artifact severity, optimizing image quality for clinical and research applications.