• The Korean Journal of Nuclear Medicine
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• v.36 no.2
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• pp.91-101
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• 2002

Purpose : The aim of this study was to identify the brain areas in which reductions of regional cerebral blood flow (rCBF) were correlated with decline of general mental function, measured by Mini-Mental State Examination (MMSE). Materials and Methods : Tc-99m HMPAO brain SPECT was peformed in 9 probable AD patients at the initial and follow-up periods of 1.8 years (average) after the first study. MMSE scores were also measured in both occasions. The mean MMSE score of the initial study 16.4 (range: 5 - 24) and the mean MMSE score of the follow-up was 8.1 (range: 0 - 17). Each SPECT image was normalized to the cerebellar activity and a correlation analysis was peformed between the level of rCBF in AD patients and the MMSE scores by voxel-based analysis using SPM99 software. Results : Significant correlation was found between the blood-flow decrease in left inferior prefrontal region (BA 47) and left middle temporal legion (BA 21) and the MMSE score changes. Additional areas such as anterior and posterior cingulate cortices, precuneus, and bilateral superior and middle prefrontal regions showed the similar trends. Conclusions : A relationship was found between reduction of regional cerebral blood flow in left prefrontal and temporal areas and decline of cognitive function in Alzheimer's disease(AD) patients. This voxel-based analysis is useful in evaluating the progress of cognitive function in Alzheimer's disease.

• The Korean Journal of Nuclear Medicine
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• v.37 no.5
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• pp.288-300
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• 2003

Purpose: To obtain regional blood flow and tissue-blood partition coefficient with time-activity curves from ${H_2}^{15}O$ PET, fitting of some parameters in the Kety model is conventionally accomplished by nonlinear least squares (NLS) analysis. However, NLS requires considerable compuation time then is impractical for pixel-by-pixel analysis to generate parametric images of these parameters. In this study, we investigated several fast parameter estimation methods for the parametric image generation and compared their statistical reliability and computational efficiency. Materials and Methods: These methods included linear least squres (LLS), linear weighted least squares (LWLS), linear generalized least squares (GLS), linear generalized weighted least squares (GWLS), weighted Integration (WI), and model-based clustering method (CAKS). ${H_2}^{15}O$ dynamic brain PET with Poisson noise component was simulated using numerical Zubal brain phantom. Error and bias in the estimation of rCBF and partition coefficient, and computation time in various noise environments was estimated and compared. In audition, parametric images from ${H_2}^{15}O$ dynamic brain PET data peformed on 16 healthy volunteers under various physiological conditions was compared to examine the utility of these methods for real human data. Results: These fast algorithms produced parametric images with similar image qualify and statistical reliability. When CAKS and LLS methods were used combinedly, computation time was significantly reduced and less than 30 seconds for $128{\times}128{\times}46$ images on Pentium III processor. Conclusion: Parametric images of rCBF and partition coefficient with good statistical properties can be generated with short computation time which is acceptable in clinical situation.

• Korean Journal of Biological Psychiatry
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• v.17 no.3
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• pp.127-135
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• 2010

Objectives : This study was conducted to compare between hallucination group and delusion group in patient with schizophrenia, using Brain $^{99m}Tc$-ECD PECT. Methods : Among 16 patients with less than 3 schizophrenic episodes, 8 patients whose initial symptom was hallucination were assigned to the hallucination group, and other 8 patients with initial sumptom of delusion were assinged to the hallucination group. All of the patients clinically evaluated using the PANSS and BPRS. Both groups of patients and 8 healthy subjects underwent $^{99m}Tc$-ECD PECT. Results : Score of thinking disturbance subscale of BPRS were significantly lower in the hallucination group than the delusion group. In SPECT analysis, the hallucination group showed significantly increased perfusion in some areas of the right temporal lobe, bilateral limbic lobes and left parietal lobe compared to delusion group. Both group had a reduced rCBF in some areas of the frontal lobe. Conclusion : The hallucniation group, compared with the delusion group, showed significantly increased regional cerebral blood flow in some regions. Therefore, this data suggests that different neural substrates may affect the process of auditory hallucination and delusion.

• Nuclear Medicine and Molecular Imaging
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• v.42 no.3
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• pp.192-200
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• 2008

To evaluate the hemodynamic changes and the predictive factors of the clinical outcome in pediatric patients with moyamoya disease, we analyzed pre/post basal/acetazolamide stress brain perfusion SPECT with automated volume of interest (VOIs) method. Methods: Total fifty six (M:F = 33:24, age $6.7{\pm}3.2$ years) pediatric patients with moyamoya disease, who underwent basal/acetazolamide stress brain perfusion SPECT within 6 before and after revascularization surgery (encephalo-duro-arterio-synangiosis (EDAS) with frontal encephalo-galeo-synangiosis (EGS) and EDAS only followed on contralateral hemisphere), and followed-up more than 6 months after post-operative SPECT, were included. A mean follow-up period after post-operative SPECT was $33{\pm}21$ months. Each patient's SPECT image was spatially normalized to Korean template with the SPM2. For the regional count normalization, the count of pons was used as a reference region. The basal/acetazolamide-stressed cerebral blood flow (CBF), the cerebral vascular reserve index (CVRI), and the extent of area with significantly decreased basal/acetazolamide- stressed rCBF than age-matched normal control were evaluated on both medial frontal, frontal, parietal, occipital lobes, and whole brain in each patient's images. The post-operative clinical outcome was assigned as good, poor according to the presence of transient ischemic attacks and/or fixed neurological deficits by pediatric neurosurgeon. Results: In a paired t-test, basal/acetazolamide-stressed rCBF and the CVRI were significantly improved after revascularization (p<0.05). The significant difference in the pre-operative basal/acetazolamide-stressed rCBF and the CVRI between the hemispheres where EDAS with frontal EGS was performed and their contralateral counterparts where EDAS only was done disappeared after operation (p<0.05). In an independent student t-test, the pre-operative basal rCBF in the medial frontal gyrus, the post-operative CVRI in the frontal lobe and the parietal lobe of the hemispheres with EDAS and frontal EGS, the post-operative CVRI, and ${\Delta}CVRI$ showed a significant difference between patients with a good and poor clinical outcome (p<0.05). In a multivariate logistic regression analysis, the ${\Delta}CVRI$ and the post-operative CVRI of medial frontal gyrus on the hemispheres where EDAS with frontal EGS was performed were the significant predictive factors for the clinical outcome (p =0.002, p =0.015), Conclusion: With probabilistic map, we could objectively evaluate pre/post-operative hemodynamic changes of pediatric patients with moyamoya disease. Specifically the post-operative CVRI and the post-operative CVRI of medial frontal gyrus where EDAS with frontal EGS was done were the significant predictive factors for further clinical outcomes.

• Journal of the Korean Academy of Child and Adolescent Psychiatry
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• v.3 no.1
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• pp.46-55
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• 1992

The pathophysiology of developmental language disorder is a highly controversial matter. In order to investigate the neural mechanisms involved in developmental language disorders, the authors studied three dimensional regional cerebral blood flow(rCBF) using Tc-99mH-MPAO in 42 children with developmental language disorders. The results are summarized as follows : 1) 61.9% (26/42) of this series revealed decreased perfusion in SPECT. 2) Regions of hypoperfusion were seen in cerebral cortex(47.6%, 20/42), thalamus(33.3%, 14/42), basal ganglia(11.9%, 5/42) and cerebellum(7.1%, 3/42). This study suggests that developmental language disorder could be due to specific functional impairment of the local brain regions which could not detected by conventional investigations such as brain CT or EEG.

• Nuclear Medicine and Molecular Imaging
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• v.41 no.2
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• pp.172-180
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• 2007

Among the nuclear medicine imaging methods available today, $H_2^{15}O-PET$ is most widely used by cognitive neuroscientists to examine regional brain function via the measurement of regional cerebral blood flow (rCBF). The short half-life of the radioactively labeled probe, $^{15}O$, often allows repeated measures from the same subjects in many different task conditions. $H_2^{15}O-$ PET, however, has technical limitations relative to other methods of functional neuroimaging, e.g., fMRI, including relatively poor time and spatial resolutions, and, frequently, insufficient statistical power for analysis of individual subjects. However, recent technical developments, such as the 3-D acquisition method provide relatively good image quality with a smaller radioactive dosage, which in turn results in more PET scans from each individual, thus providing sufficient statistical power for the analysis of individual subject's data. Furthermore, the noise free scanner environment $H_2^{15}O$ PET, along with discrete acquisition of data for each task condition, are important advantages of PET over other functional imaging methods regarding studying state-dependent changes in brain activity. This review presents both the limitations and advantages of $^{15}O-PET$, and outlines the design of efficient PET protocols, using examples of recent PET studies both in the normal healthy population, and in the clinical population.

• Nuclear Medicine and Molecular Imaging
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• v.41 no.6
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• pp.530-537
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• 2007

Purpose: The aim of this study is to assess the specific patterns of regional cerebral blood flow (rCBF) in patients with the early stage of subcortical vascular dementia (SVaD) and Alzheimer's disease (AD) using Tc-99m HMPAO SPECT, and to compare the differences between the two conditions. Materials and Methods: Sixteen SVaD, 46 AD and 12 control subjects participated in this study. We included the patients with SVaD and AD according to NINCDS-ADRDA and NINDS-AIREN criteria. They were all matched for age, education and clinical dementia rating scores. Three groups were evaluated by Tc-99m HMPAO SPECT using statistical parametric mapping (SPM) for measuring rCBF. The SPECT data of patients with SVaD and AD were compared with those of normal control subjects and then compared with each other. Results: SPM analysis of the SPECT image showed significant perfusion deficits on the right temporal region and thalamus, left insula and superior temporal gyrus, both cingulate gyri and frontal subgyri in patients with SVaD and on the left supramarginal gyrus, superior temporal gyrus, postcentral gyrus and inferior parietal lobule, right fugiform gyrus and both cingulate gyri in AD compared with control subjects (uncorrected p<0.01). SVaD patients revealed significant hypoperfusion in the right parahippocampal gyrus with cingulated gyrus, left insula and both frontal subgyral regions compared with AD (uncorrected p<0.01). Conclusion: Our study shows characteristic and different pattern of perfusion deficits in patients with SVaD and AD, and these results may be helpful to discriminate the two conditions in the early stage of illness.

• The Korean Journal of Nuclear Medicine
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• v.31 no.3
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• pp.320-329
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• 1997

Neuroanatomic substrate of autism has been the subjects of continuing investigation. Because previous studies had not demonstrated consistent and specific neuroimaging findings in autism and most studies comprised adults and school-aged children, we performed a retrospective review in search of common functional and anatomical abnormalities with brain SPECT using Tc-99m ECD and correlative MRI The patient population was composed of 18 children aged 28 to 89 months(mean age : 55 months) who met the diagnostic criteria of autism as defined in the DSM-IV and CARS. Brain SPECT was performed after intravenous injection of 185-370MBq of Tc-99m ECD using brain dedicated annular crystal gamma camera. MRI was performed in all patients including T1, T2 axial and T1 sagittal sequences. SPECT data were visually assessed. Thirteen patients had abnormal SPECT scan revealing focal areas of decreased perfusion. Decreased perfusion of cerebellar vermis(12/18), cerebellar hemisphere(11/18), thalami(13/18), basal ganglia(4/18), posterior parietal(7/18), and temporal(4/18) area were noted on brain SPECT. Whereas, only 3 patients had abnormal MR findings which were subtle volume loss of parieto-occipital white matter in 3 and mild thinning of posterior body of corpus callosum in 2 and slightly decreased volume of cerebellar vermis in 1. Comparison of the numbers of abnormal findings revealed that regional cerebral blood flow (rCBF) abnormalities seen on SPECT were more numerous than anatomical abnormalities seen on MRI. In conclusion, extensive perfusion impairment involving cerebellum, thalami and parietal lobe were found in this study. SPECT may be more sensitive in reflecting pathophysiology of autism than MRI. However, further studies are mandatory to determine the significance of thalamic and parietal perfusion impairment in autism.