MRI volumetric measurement of hippocampal formation based on statistic parametric mapping / 中华放射学杂志

ABSTRACT

Objective To study MRI volumetric measurement of hippocampal formation using statistic parametric mapping(SPM) software and to discuss the value of the method applied to Alzheimer's disease (AD).Methods The SPM software was used to divide the three-dimensional MRI brain image into gray matter, white matter and CSF separately.The bilateral hippocampal formations in both AD group and normal control group were delineated and the volumes were measured.The SPM method was compared with conventional method based on region of interest (ROI), which was the gold standard of volume measurement The time used in measuring the volume by these two methods were respectively recorded and compared by two independent samples' t test.Moreover, 7 physicians measured the left hippocampal formation of one same control with both of the two methods.The frequency distribution and dispersion of data acquired with the two methods were evaluated using standard deviation coefficient Results (1)The volume of the bilateral hippocampal formations with SPM method was (1.88±0.07) cm~3 and (1.93±0.08) cm~3 respectively in the AD group, while was (2.99 ±0.07) cm~3 and (3.02 ±0.06) cm~3 in the control group .The volume of bilateral hippocampal formations measured by ROI method was (1.87 ±0.06) cm~3 and (1.91 ±0.09) cm~3 in the AD group, while was (2.97 ±0.08)cm~3 and (3.00 ±0.05) cm~3 in the control group.There was no significant difference between SPM method and conventional ROI method in the AD group and the control group(t=1.500, 1.617, 1.095, 1.889,P> 0.05) .However, the time used for delineation and volume measurement was significantly different.The time used in SPM measurement was (38.1 ±2.0) min, while that in ROI measurement was (55.4 ±2.4) min (t=-25.918, P<0.01).(2)The average volumes of the left hippocampal formation with the two methods measured by the 7 physicians were (2.86±0.20) and (2.76±0.52) cm~3 respectively.The frequency distribution of hippocampal formation volume measured by SPM method and ROI method was different.The CV_(SPM) was 7% and the CV_(ROI) was 19%.Conclusions The borders of hippocampus formation in brain gray matter could be conveniently delineated by SPM software.The accuracy and repetition of measurement was improved by SPM method.The shorter time used in measurement made it possible for MRI volumetric measurement of hippocampal formation to be applied in assessment of relevant neuropsychiatric diseases.