Evaluation of Hippocampal Volume Based on Various Inversion Time in Normal Adults by Manual Tracing and Automated Segmentation Methods

Abstract

Purpose: To investigate the value of image post-processing software (FreeSurfer,IBASPM [individual brain atlases using statistical parametric mapping software])and inversion time (TI) in volumetric analyses of the hippocampus and to identifydifferences in comparison with manual tracing. Materials and Methods: Brain images from 12 normal adults were acquired usingmagnetization prepared rapid acquisition gradient echo (MPRAGE) with a slicethickness of 1.3 mm and TI of 800, 900, 1000, and 1100 ms. Hippocampal volumeswere measured using FreeSurfer, IBASPM and manual tracing. Statistical differenceswere examined using correlation analyses accounting for spatial interpretationspercent volume overlap and percent volume difference. Results: FreeSurfer revealed a maximum percent volume overlap and maximumpercent volume difference at TI = 800 ms (77.1 ± 2.9%) and TI = 1100 ms (13.1 ±2.1%), respectively. The respective values for IBASPM were TI = 1100 ms (55.3 ±9.1%) and TI = 800 ms (43.1 ± 10.7%). FreeSurfer presented a higher correlation thanIBASPM but it was not statistically significant. Conclusion: FreeSurfer performed better in volumetric determination than IBASPM. Given the subjective nature of manual tracing, automated image acquisition andanalysis image is accurate and preferable.