Automated hippocampal volume measurement: agreement analysis between HIPS and volBrain software.

Abstract

Objective: To perform an agreement analysis between volBrain and HIPS software for measuring hippocampal volume and its associated asymmetry index.

Materials and methods: We evaluated volumetric T1-weighted magnetic resonance imaging scans from radiologically normal subjects (n = 50; age range, 25-75 years). Correlation and Bland-Altman plots were generated. The Pearson correlation coefficient (r) and the intraclass correlation coefficient of absolute agreement between volBrain and HIPS software were calculated for each measurement.

Results: For each hippocampus and its combined volume, a very high correlation was found between the methods (r ≥ 0.96 for absolute values and r ≥ 0.93 for relative values), along with a systematic bias (primarily additive). Consistently, HIPS (with the Kulaga-Yoskovitz protocol) reported smaller volumes than did volBrain. The average difference ranged from 8.2% to 9.1% for absolute values and from 7.9% to 8.7% for relative values. The asymmetry index exhibited a strong correlation (r = 0.82) with no significant bias, although 14% of cases showed opposite signs. The average asymmetry index difference was 32.7%. The intraclass correlation coefficient of absolute agreement ranged from 0.61 to 0.83, reflecting moderate to good agreement overall.

Conclusion: Our results indicate that the two methods are not interchangeable for evaluating hippocampal volume and its associated asymmetry index.