Comparison of T1w, T2w, and T1w/T2w MRI methods for perivascular space quantification.

PURPOSE: T1 weighted (T1w), T2 weighted (T2w) and T1w/T2w have been used for perivascular space (PVS) segmentation. However, studies on the relationships or comparisons across them are few with limited sample sizes and yield inconsistent results. Examining those relationships can help to understand the consistency and reliability of PVS measurements for each method. METHOD: This study systematically examined the relationships among PVS volumes and counts derived from T1w, T2w, and combined T1w/T2w methods with 2,654 participants. PVS segmentation was performed using Frangi's filter. Measurement repeatability and sensitivity to physiological and pathological differences were compared across the three approaches. RESULTS: Strong correlations were observed for T1w (R² = 0.89-0.96) and T2w (R² = 0.98-0.99) relative to the T1w/T2w method, as well as T1w vs. T2w methods (R²=0.87-0.95). All three methods showed robust repeatability with no significant differences observed in test-retest analyses. Significantly higher PVS (including volume and count) was found in males. All three methods could also identify physiological and pathological variations. Significant differences were observed between participants with poor and good sleep quality, as well as between participants with hypertension and non-hypertension across all methods. However, the T1w method demonstrated weaker group separation, with smaller mean differences in PVS measurements than those observed using the T2w and T1w/T2w methods. CONCLUSION: The findings support the use of all three methods for automated PVS quantification in clinical and research settings, while T2w and combined T1w/T2w approaches potentially detect more PVS.