Aim: Several methods have been proposed to analyse radiopharmaceutical uptake in regional cerebral blood flow (rCBF) studies. Volume of Interest (VOI) analysis evaluates the 3D data in a predefined region. Principal Component Analysis (PCA), by reducing the number of VOIs to factors, takes also into account correlations between variables, reflecting presumably human brain anatomo-functional connectivity. The aim of this study was to assess rCBF differences in two groups of depressed patients and normal controls and to compare the results according to these two analysis methods. Material and Methods: 70 outpatients bearer of Major Depressive Disorder (MDD) along with audiological and physical symptoms and 66 normal controls (CTR) were studied by 99m-Tc-HMPAO SPET. rCBF was analysed in twenty-seven VOIs, bilaterally, automatically defined by a standardisation software (CBA). PCA was used to reduce the number of variables by grouping the VOIs in positively correlated factors. The differences between radiopharmaceutical uptake in MDD and CTR found at VOI level were then compared to those found at factor level. Results: PCA resulted in 11 factors that significantly interacted with groups (p<0.001). Increased rCBF was shown by both methods with several overlaps in frontal and temporal lobes and in central structures. All VOIs differing significantly between MDD and CTR were included in three out of the four significantly different factors. The last significant factor, that grouped VOIs belonging to temporal and parietal lobe, did not include any VOI reaching singularly the level of significance (p<0.05). Conclusion: Increased rCBF was found in a selected group of MDD outpatients. PCA grouped regions in factors according to their reciprocal rCBF positive relationships and highlighted significances in areas larger than those found at VOI level. One factor was significantly different between groups independently from significance in the single VOIs strengthening the value of investigating the correlation between variables. Factors represent cerebral areas with possible anatomo-functional connections and their analysis might help in shedding light on the interactions between different regions in MDD.
Principal Component Analysis and Volumes of Interest Analysis in Depressed Patients by 99m-Tc-HMPAO SPET - A Methodological Comparison
Pagani M;Salmaso D;
2003
Abstract
Aim: Several methods have been proposed to analyse radiopharmaceutical uptake in regional cerebral blood flow (rCBF) studies. Volume of Interest (VOI) analysis evaluates the 3D data in a predefined region. Principal Component Analysis (PCA), by reducing the number of VOIs to factors, takes also into account correlations between variables, reflecting presumably human brain anatomo-functional connectivity. The aim of this study was to assess rCBF differences in two groups of depressed patients and normal controls and to compare the results according to these two analysis methods. Material and Methods: 70 outpatients bearer of Major Depressive Disorder (MDD) along with audiological and physical symptoms and 66 normal controls (CTR) were studied by 99m-Tc-HMPAO SPET. rCBF was analysed in twenty-seven VOIs, bilaterally, automatically defined by a standardisation software (CBA). PCA was used to reduce the number of variables by grouping the VOIs in positively correlated factors. The differences between radiopharmaceutical uptake in MDD and CTR found at VOI level were then compared to those found at factor level. Results: PCA resulted in 11 factors that significantly interacted with groups (p<0.001). Increased rCBF was shown by both methods with several overlaps in frontal and temporal lobes and in central structures. All VOIs differing significantly between MDD and CTR were included in three out of the four significantly different factors. The last significant factor, that grouped VOIs belonging to temporal and parietal lobe, did not include any VOI reaching singularly the level of significance (p<0.05). Conclusion: Increased rCBF was found in a selected group of MDD outpatients. PCA grouped regions in factors according to their reciprocal rCBF positive relationships and highlighted significances in areas larger than those found at VOI level. One factor was significantly different between groups independently from significance in the single VOIs strengthening the value of investigating the correlation between variables. Factors represent cerebral areas with possible anatomo-functional connections and their analysis might help in shedding light on the interactions between different regions in MDD.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
