Towards characterizing the regional cerebral perfusion in evaluating the severity of major depression disorder by SPECT/CT

Objectives: Major depressive disorder (MDD) is a common mental disorder worldwide, and can lead to suicide. Unfortunately, most MDD sufferers have never received effective treatments. One of the main barriers is inaccurate assessment. In this study, we used ^99mTc-ECD SPECT/CT to characterize the regional cerebral blood flow (rCBF) findings of MDD patients, and to explore more objective assessment modalities of MDD which are also safe, accurate and convenient in a clinical setting.

Methods: 74 patients who fulfilled the DSM-IV criteria for unipolar MDD were enrolled in this study. The severity of MDD was assessed by three trained psychiatrists, based on rating obtained with Hamilton Rating Scale for Depression (HAMD) and Hamilton Rating Scale for Anxiety (HAMA). ^99mTc-ECD rCBF SPECT/CT was performed in all patients before receiving the treatment. The CT attenuation-corrected SPECT imaging data were automatically registered, analysed and compared with a normalized database by 3D-SSP. An additional quantitative analysis was performed in three targeted areas (caudate nucleus, globus pallidus and hippocampus) which were not completely shown in Brodmann areas. We summarize the abnormal rCBF in MDD, analyzed the gender differences and the differences of marital status in the score of HAMD, and assessed the relationship among the score of HAMD, the score of HAMA, the age of MDD patients, the duration of MDD and the number of years for education.

Results: The mean score for the HAMD in the MDD patients was 25.49±6.00, and the score for HAMA was 23.12±5.83. There was a positive correlation between two scores (r=0.732, p=0.000). But the score of HAMD showed no correlations with the ages of MDD patients (r=0.134, p=0.255), the duration of MDD (r=-0.140, p=0.235) or the number of years for education (r=-0.195, p=0.096). Besides, the MDD women (26.66±5.11) had higher HAMD scores than the MDD men (22.52±7.08, t=2.801, p=0.007). And there was no significant difference in the score of HAMD between married people and non-divorced singles (t=0.436, p=0.664). Among many brain regions with abnormal z-score, left ventral anterior cingulate cortex B24, left inferior prefrontal gyrus B47, right associative visual cortex B19 and right retrosplenial cortex B29 showed a correlationship with the score of HAMD (R=0.423, F=3.752, p=0.008).

Conclusion: There were multiple abnormalities of rCBF distributed throughout the brains of MDD patients. Although the mechanism underlying the correlation has not yet been defined, our findings indicate that resting-state rCBF alterations in the DMN of the brain may be associated with the severity of MDD. The rCBF SPECT/CT can provide an objective imaging basis for the pathogeny analysis and severity evaluation of MDD. And it might be considered as a potential biomarker in identifying the various endophenotypes of MDD and monitoring therapeutic efficacy in the management of MDD. Key words: major depressive disorder; cerebral blood flow; SPECT/CT; ^99mTc-ECD