Evaluation of Geometric Correspondence of kV X-ray Images, Electric Portal Images and Digitally Reconstructed Radiographic Images / 의학물리

In this study we estimated a geometric correlation among digitally reconstructed radiographic image (DRRI), kV x-ray image (kVXI) from the On-Board Imager (OBI) and electric portal image (EPI). To verify geometric correspondence of DRRI, kVXI and EPI, specially designed phantom with indexed 6 ball bearings (BBs) were employed. After accurate setup of the phantom on a treatment couch using orthogonal EPIs, we acquired set of orthogonal kVXIs and EPIs then compared the absolute positions of the center of the BBs calculated at each phantom plane for kVXI and EPI respectively. We also checked matching result for obliquely incident beam (gantry angle of 315 degrees) after 2D-2D matching provided by OBI application. A reference EPI obtained after initial setup of the phantom was compared with 10 series of EPIs acquired after each 2D-2D matching. Imaginary setup errors were generated from -5 mm to 5 mm at each couch motion direction. Calculated positions of all center positions of the BBs at three different images were agreed with the actual points within a millimeter and each other. Calculated center positions of the BBs from the reference and obtained EPIs after 2D-2D matching agreed within a millimeter. We could tentatively conclude that the OBI system was mechanically quite reliable for image guided radiation therapy (IGRT) purpose.

Application of SPM for Comparison of Striatal Dopamine Transporter Density between the Early Stage of the Parkinsonian Variant of Multiple System Atrophy and Parkinson's Disease

OBJECTIVE: Nigrostriatal dopaminergic neuronal degeneration is common to idiopathic Parkinson's disease(PD) and multiple system atrophy(MSA); although the topography of the nigral cell loss and striatal dopamine deficiency may differ. Currently, several functional neuroimaging techniques have been developed to differentiate between these two diseases. However, since the basal ganglia are usually poorly delineated in parkinsonian disorders on most functional neuroimaging techniques, most studies have failed to show the different pathologic changes among the parkinsonian disorders. In this study, we investigated alternation in regional loss of dopamine transporter binding using statistical parametric mapping(SPM) in patients with PD and the parkinsonian variant of MSA(MSA-P). METHODS: Ten PD and five MSA-P patients within 3 years of duration were studied with dual isotope brain SPECT following simultaneous injection of 370 MBq [99mTc] HMPAO and 111 MBq [123I] IPT. RESULTS: The basal ganglia were clearly visible on the fusion image, which was possible for quantitative and sta- tistical analysis. MSA-P patients showed significant loss of dopamine transporter binding in the left globus pallidus, anterior putamen and caudate nucleus in comparison to PD patients. CONCLUSION: This result may provide a useful tool to differentiate the pattern of loss of dopamine transporter bin- ding between PD and MSA-P.

Working Memory Deficits of Facial Images in Patients with Schizophrenia: fMRI Investigation / 신경정신의학

OBJECTIVES: Impaired processing of facial information is one of the broad ranges of cognitive deficits seen in patients with schizophrenia. We aimed to elucidate the differences in brain activities involved in the process of facial working memory between schizophrenic patients and healthy comparison subjects. METHODS: Twelve patients with schizophrenia were recruited along with twelve demographically matched healthy volunteers as a comparison group. Functional magnetic resonance imaging (fMRI) was used to assess cortical activities during the performance of a 2-back working memory paradigm using images of neutral faces as mnemonic content. RESULTS: The patient group performed the tasks with reduced accuracy. Group analysis revealed that the left fusiform gyrus, the right superior frontal gyrus, the bilateral middle frontal gyri/insula, the left middle temporal gyrus, the precuneus, the quadrangular lobules and the vermis of cerebellum showed decreased cortical activities in the patient group. On the other hand, an increased level of activation in the lateral prefrontal cortex and the parietal lobule was observed from the patient group, all in the right hemisphere. CONCLUSION: A decreased level of activity in the left fusiform gyrus among the patient group implicates inefficient processing of facial information. An increased level of activation in prefrontal and parietal neural networks from the patient group confirms earlier findings on the impaired working memory of patients with schizophrenia.

Quantitative Evaluation of Regional Cerebral Blood Flow by Visual Stimulation in 99mTc - HMPAO Brain SPECT / 대한핵의학회잡지

No abstract available.