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

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

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.

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.

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