Main Article Content
Role of radiology in psychiatry: a review
Abstract
Objective: To assess the contributions of radiological studies to current level of understanding of the pathophysiological mechanisms that underlie psychiatric symptoms/ disorders and their treatment.
Data sources: Published articles in indexed journals.
Study selection: Radiological studies of psychiatric populations with emphasis on neuroimaging techniques.
Data extraction: Information concerning aetiological factors, pathophysiological mechanisms and treatment of psychiatric disorders were scrutinized.
Data synthesis: Structural changes on CT, in schizophrenia include enlargement of the ventricles, cerebral sulci and fissure. MRI studies in these patients confirm significant differences in ventricular volume and medial temporal structures. Functional changes on PET, SPECT and fMRI in depressed patients include altered cerebral blood flow and metabolism in the pre-frontal cortex, anterior cingulate, caudate nucleus, amygdala and thalamus, suggesting abnormal interactions in several brain regions. Drug distribution can be imaged by MRS and this has shown brain lithium level to be about half the plasma level. PET and SPET studies have demonstrated that unlike the classical antipsychotics (e.g. chlorpromazine), atypical antipsychotic drugs such as risperidone and clozapine have high cortical serotonin (5HT2) receptor occupancy (80-90%), thus challenging the theory of a simple relationship between dopamine (D2) receptor occupancy (blocked by classical antipsychotics) and clinical efficacy.
Conclusion: Radiological studies of psychiatric populations add to available knowledge on the biological aspects of psychiatry. It is therefore essential to provide and update radiological facilities in mental health institutions in developing countries.
East African Medical Journal Vol. 82(5) 2005: 260-266
Data sources: Published articles in indexed journals.
Study selection: Radiological studies of psychiatric populations with emphasis on neuroimaging techniques.
Data extraction: Information concerning aetiological factors, pathophysiological mechanisms and treatment of psychiatric disorders were scrutinized.
Data synthesis: Structural changes on CT, in schizophrenia include enlargement of the ventricles, cerebral sulci and fissure. MRI studies in these patients confirm significant differences in ventricular volume and medial temporal structures. Functional changes on PET, SPECT and fMRI in depressed patients include altered cerebral blood flow and metabolism in the pre-frontal cortex, anterior cingulate, caudate nucleus, amygdala and thalamus, suggesting abnormal interactions in several brain regions. Drug distribution can be imaged by MRS and this has shown brain lithium level to be about half the plasma level. PET and SPET studies have demonstrated that unlike the classical antipsychotics (e.g. chlorpromazine), atypical antipsychotic drugs such as risperidone and clozapine have high cortical serotonin (5HT2) receptor occupancy (80-90%), thus challenging the theory of a simple relationship between dopamine (D2) receptor occupancy (blocked by classical antipsychotics) and clinical efficacy.
Conclusion: Radiological studies of psychiatric populations add to available knowledge on the biological aspects of psychiatry. It is therefore essential to provide and update radiological facilities in mental health institutions in developing countries.
East African Medical Journal Vol. 82(5) 2005: 260-266
