Comparison the effect of two analysis methods of brain volume: Absolute brain volume and brain volume normalized with intracranial volume in methamphetamine abusers

Introduction: Magnetic Resonance Imaging (MRI) documented abnormal brain structure in methamphetamine abusers with inconsisting results. It is likely that this discrepency could be from different analysis methods for example absolute volume analysis method and intracranial volume(ICV) normalization. Objectives: To compare the effect of analysis method between absolute volume analysis and normalized volume with ICV analysis among methamphetamine abusers (MA) and healthy controls (HC) groups. Materials and methods: Ten MAs and 14 HCs with gender and age matched were recruited. MRI of brain were acquired on 1.5 Tesla MR Scanner (Achieva, Philips, Netherland). Axial T1-weighted images with 3D FFE pulse sequence were used for MRI acquisition with the following data acquisition parameters: TE/TR =4.6/20 ms, FOV = 24 cm, 256x128 imaging matrix and 120 slices. Measurement of brain volume were performed with Freesurfer (FS) version 5.3. Absolute volume and normalized volume with ICV between HCs and MAs groups were compared. Pearson correlation was used to find the correlation of the brain volume between the two methods. Results: In absolute volume analysis method, we observed consistent significant larger brain volumes in HCs compared to MAs. A positive correlation in most parts of brains was observed between absolute volume analysis method and ICV in HCs and MAs group. In contrast, negative correlation in most parts f brains was observed between ICV normalized volume method and ICV between HC and MA. The different of correlation for each brain region between HCs and MAs could be associated with the effect of methamphetamine. Conclusion: The difference of the two analysis methods give similar results but varied in different brain regions. The choice of analysis method should be carefully selected in brain imaging study.