PURPOSE: Cross-modality coregistration of positron emission tomography (PET) and magnetic resonance imaging (MR) could enhance the clinical information. In this study we propose a refined technique to improve the robustness of registration, and to implement more realistic visualization of the coregistered images. MATERIALS AND METHODS: Using the sinogram of PET emission scan, we extracted the robust head boundary and used boundary-enhanced PET to coregister PET with MR. The pixels having 10% of maximum pixel value were considered as the boundary of sinogram. Boundary pixel values were exchanged with maximum value of sinogram. One hundred eighty boundary points were extracted at intervals of about 2 degree using simple threshold method from each slice of MR images. Best affined transformation between the two point sets was performed using least square fitting which should minimize the sum of Euclidean distance between the point sets. We reduced calculation time using pre-defined distance map. Finally we developed an automatic coregistration program using this boundary detection and surface matching technique. We designed a new weighted normalization technique to display the coregistered PET and MR images simultaneously. RESULTS: Using our newly developed method, robust extraction of head boundary was possible and spatial regishation was successfully performed. Mean displacement error was less than 2.0mm. In visualization of coregistered images using weighted normalization method, structures shown in MR image could be realistically represented. CONCLUSION: Our refined technique could practically enhance the performance of automated three dimensional coregistration.
Brain* ; Head ; Magnetic Resonance Imaging ; Positron-Emission Tomography

The authors compared and analysed planned extracapsular cataract extraction(ECCE) and Kelman phacoemulsification(KPE) on the 1000 cases out of 1546 cases which had undergone cataract operation during the period of September, 1983 through June, 1989. The results were as follows; 1. Postoperative visual acuity of 0.5 or better was achieved in 96%(960 eyes) and 1.0 or better in 67.6%(676 eyes). Average of visual acuity was similar each other: 0.92 +/- 0.24 in planned ECCE and 1.00 +/- 0.21 in KPE. 2. The mean spherical equivalent of required spectacle lens power was similar too: -1.07D +/- 1.51 in total, -1.08D +/- 1.57 in planned ECCE and -1.05D +/- 1.42 in KPE. 3. The mean postoperative astigmatism was -0.81D +/- 1.05 in total, -0.98D +/- 1.15 in planned ECCE and -0.54D +/- 0.79 in KPE. There was significant correlation between two groups(P<0.01). 4. The difference between predicted and postoperative refraction in terms of spherical equivalent was -0.36D +/- 1.12 in total, -0.36D +/- 1.12 in planned ECCE and -0.37D +/- 1.11 in KPE with no significant different value. The difference by Binkhorst formula was -0.50D +/- 1.10, and -0.06D +/- 1.09, the significant correlative value by regression SRK formula(P<0.05). 5. Mean changes of corneal refractive power was 0.43D +/- 0.99 in horizontal meridian and -0.21D +/-1.14 in vertical meridian in planned ECCE and 0.23D +/- 0.72 in horizontal meridian and 0.01D +/- 0.90 in vertical meridian in KPE. There was significant correlation between two groups(P<0.01). 6. The correlation between postoperative corneal astigmetism and actual astigmatism by skiascopy was very close: regression coefficient was 0.64087 in total, 0.62698 in planned ECCE and 0.62026 in KPE respectively(P<0.01).
Astigmatism ; Cataract ; Retinoscopy ; Visual Acuity

Objectives: The purpose of study is to evaluate serial MR imaging of myocardial infarction using non-surgical model of myocardial infarction after percutaneous transcatheter coronary arterial embolization in dogs. MATERIALS AND METHODS: We evaluated serial pre- and post-contrast MR images with Gd-DTPA (gadolinium-diethylenetriamine-pentaacetic acid) of heart of the eleven mongrel dogs (immediate group (n=3), one week group (n=3), three weeks group (n=5)) after making non-surgically induced myocardial infarction. We confirmed the infarct with TTC staining and microscopically. The location and extents of the myocardial infarction were correlated. RESULTS: A total of 24 MR images were archived; 11 images of the immediate post-embolic period, 8 images of one-week follow-up, and five of 3-week follow-up images. Comparing with the signal intensity of normal myocardium, immediate post-embolic MR images showed low or iso signal intensities (SI) of the infarct area on T1-weighted images (T1WI) and high SI on T2-weighted images (T2WI). No contrast enhancement with Gd-DTPA was made in all cases of the immediate post-embolic MRI. One-week and 3-week follow-up MR images showed low or iso SI on T1WI and slight high or iso SI on T2WI. Contrast enhancement images in both one-week and 3-week follow-up MRI showed denser enhancement of infarct area in one-week follow-up. The myocardial wall thinning was seen in 5 of eight dogs after one week and in 3 of five after 3 weeks. CONCLUSION: In non-surgical animal models of myocardial infarction, MR images showed low or iso SI on T1WI, and high SI on T2WI in various stages, and contrast enhancement was maximum after one week and gradual decrease to 3 weeks. The myocardial wall thinning was seen in one-to 3-week follow-up MR images.
Animals* ; Dogs ; Follow-Up Studies ; Gadolinium DTPA ; Heart ; Magnetic Resonance Imaging* ; Models, Animal* ; Myocardial Infarction* ; Myocardium

In a jaundiced patient, it is important to ascertain as early as possible whether the bile duct is dilated. Ultrasonography, computed tomography & conventional cholangiography are widely accepted methods of determining the size of the extrahepatic bile ducts. But there is a considerable discrepancy among the size of the bile duct as measured from them. So the author analyzed and compared the respective diameters of the bile ducts in Korean normal adults as measured from cadaver, IV cholangiography, ultrasoud and computed tomography. The materials were 45 cases of cadaver, 38 cases of IV cholangiography, 100 cases of ultrasonography & 55 cases of computed tomography. The results were as follows ; 1. The diameters of the bile ducts were 7.58±2.26mm at CHD & 8.04±2.42mm at CBD from cadaver ; 5.38±1.90mm at CHD & 6.58±2.37mm at CBD from IV cholanglography ; 3.24±1.13mm at CHD & 4.71±1.48mm at CBD from ultrasonography ; and 4.56±1.51mm at CHD & 5.87±1.68mm at CBD from computed tomography. 2. The diameter of the bile duct was greatest in cadaver, and then reduced in IV cholangiography, computed tomography and ultrasonography in this orde.r 3. There were no size discrepancy between the diameter of the common hepatic duct and that of the common bile duct. 4. There were no discrepanry of the diameter of the bile duct by sex.
Adult* ; Bile Ducts* ; Bile Ducts, Extrahepatic ; Bile* ; Cadaver ; Cholangiography ; Common Bile Duct ; Hepatic Duct, Common ; Humans ; Ultrasonography

As the healthcare environment has changed both socially and politically importance of public health doctors' roles has increased and ongoing revision of their roles is also needed in Korea. However, many problems have decreased the job satisfaction of public health doctors. This study aims to determine the factors that influence public health doctors' satisfaction. The survey was conducted over the course of 2 months by questionnaire methodology. A total of 881 respondents (response rate, 90.1%) participated and 778 valid responses were analyzed using SAS version 9.1. Items about arranged organization, work task, employee welfare and services, education, public health doctor's system, and the role of public health doctors were included in the questionnaire. It was found that the satisfaction of many respondents was not high and they had negative perceptions of arranged organization, work, environment, employee welfare and services, education, system, and their own role. Although the public health doctors have professional knowledge of healthcare, they were not satisfied with their role because they were required to do inappropriate work, improperly arranged and found performing work difficult when treated unfairly or not paid fairly. Therefore, policies focused on financial compensation or system improvement must be established to increase the satisfaction of public health doctors. This study's limitation was that the survey was done through two modalities. However, it is meaningful that issues related to the public health doctors were dealt with more comprehen-sively in this study than other studies.
Compensation and Redress ; Delivery of Health Care ; Job Satisfaction ; Korea ; Phenothiazines ; Public Health ; Surveys and Questionnaires ; Surveys and Questionnaires

PURPOSE: To evaluate the effectiveness of radioiodine treatment for metastatic thyroid carcinoma, we reviewed results of radioactive iodine treatment in patients with functional lung or bone metastases. MATERIALS ANF METHODS: Of 760 patients who were treated for differentiated thyroid cancer between 1984 and 1998, we detected pulmonary metastases and bone metastases in 76 patients (10.0%) and 20 patients (2.6%), respectively. Among them, we could evaluate the effectiveness of I-131 therapy in 53 patients with lung metastases and 15 patients with bone metastases. RESULTS:Of 53 patients who received I-131 therapy with a mean cumulative dose of 26.2 GBq (1.1-84.4 GBq) for pulmonary metastases, metastatic lung lesions completely resolved in 19 patients (35.8%) and improved in 22 patients (41.5%). In 13 of 19 patients with complete remission of pulmonary metastases, the total accumulated dose of I-131 was less than 18.5 GBq. We found 43 sites of metastatic bone lesions in 15 patients with bone metastases. Of 29 lesions which received I-131 therapy, metastatic lesions improved in 14 sites (48.3%), but did not change or progress in 15 sites (51.7%) despite the I-131 therapy. Three lesions were completely cured with a combination treatment of surgery(+/- external radiotherapy) and I-131 therapy, and the other 11 lesions improved. CONCLUSION: Radioactive iodine treatment gives favorable results for pulmonary metastases. However, for bone metastases, there might be a need to use combination therapy including I-131 and surgery or external irradiation.
Atrial Natriuretic Factor ; Humans ; Iodine ; Lung ; Neoplasm Metastasis* ; Thyroid Gland* ; Thyroid Neoplasms*

PURPOSE: To localize and compare the neural basis of verbal and visual human working memory, we erforrned functional activation study using H2O PET. MATERIALS AND METHODS: Repeated H213O PET scans with one control and three different activation tasks were performed on six right-handed narmal volunteers. Each activation task was composed of 13 matching trials. On each trial, four targets, a fixation dot and a probe were presented sequentially and subjects task was to press a response button to indicate whether or nat the probe was one of the previous targets. Short meaningful Korean words, simple drawings and monochromic pictures of human faces were used as matching objects for verbal or visual memory. All the images were spatially normalized and the differences between control and activation states were statistically analyzed using SPM96. RESULTS: Statistical analysis of verbal memory activation with short words showed activation in the left Broca's area, premotor cortex, cerebellum and right cingulate gyrus. In verbal memory with simple drawings, activation was shown in the larger regions including where activated with short words and left superior temporal cortex, basal ganglia, thalamus, prefrontal cortex, anterior portion of right superior temporal gyrus and right infero-lateral frontal cortex. On the other hand, the visual memory task activated predominantly right-sided structures, especially inferior frontal cortex, supplementary motor cortex and superior parietal cortex. CONCLUSION: The results are :consistent with the hypothesis of the laterality and dissociation of the verbal and visual workmg memory from the invasive electrophysiological studies and emphasize the pivotal role of frontal cortex and cingulate gyrus in working memory system.
Basal Ganglia ; Brain Mapping* ; Brain* ; Cerebellum ; Electrons* ; Gyrus Cinguli ; Hand ; Humans* ; Memory ; Memory, Short-Term* ; Motor Cortex ; Positron-Emission Tomography* ; Prefrontal Cortex ; Rabeprazole ; Thalamus ; Volunteers

PURPOSE: To obtain regional blood flow and tissue-blood partition coefficient with time-activity curves from H2 (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). H2 (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 addition, parametric images from H2 (15) O dynamic brain PET data performed 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 quality and statistical reliability. When CAKS and LLS methods were used combinedly, computation time was significantly reduced and less than 30 seconds for 128x128x46 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.
Bias (Epidemiology) ; Brain ; Electrons* ; Healthy Volunteers ; Humans ; Least-Squares Analysis ; Noise ; Positron-Emission Tomography* ; Regional Blood Flow

PURPOSE: The aim of this study was to determine whether crossed cerebellar hyperperfusion (CCH) was helpful in discriminating mesial from lateral temporal lobe epilepsy (TLE) and what other factors were related in the development of CCH on ictal brain SPECT. MATERALS AND METHODS: We conducted retrospective analysis in 59 patients with TLE (M:41, F:18; 27.4+/-7.8 years old; mesial TLE: 51, lateral TLE: 8), which was confirmed by invasive EEG and surgical outcome (Engel class I , II). All the patients underwent ictal Tc-99m HMPAO brain SPECT and their injection time from ictal EEG onset on video EEG monitoring ranged from 11 sec to 75 sec (32.6+/-19.5 sec) in 39 patients. Multiple factors including age, TLE subtype (mesial TLE or lateral TLE), propagation pattern (hyperperfusion localized to temporal lobes, spread to adjacent lobes or contralateral hemisphere) and injection time were evaluated for their relationship with CCH using multiple logistic regression analysis RESULTS: CCH was observed in 18 among 59 patients. CCH developed in 29% (15/51) of mesial TLE patients and 38% (3/8) of lateral TLE patients. CCH was associated with propagation pattern; no CCH (0/13) in patients with hyperperfusion localized to temporal lobe, 30% (7/23) in patients with propagation to adjacent lobes, 48% (11/23) to contralateral hemisphere. Multiple logistic regression analysis revealed that propagation pattern (p=0.01) and age (p=0.02) were related to the development of CCH. CONCLUSION: Crossed cerebellar hyperperfusio ictal brain SPECT did not help differentiate mesial from lateral temporal lobe epilepsy. Crossed cerebellar hyperperfusion was associated with propagation pattern of temporal lobe epilepsy and age.
Brain* ; Electroencephalography ; Epilepsy ; Epilepsy, Temporal Lobe* ; Humans ; Logistic Models ; Retrospective Studies ; Technetium Tc 99m Exametazime* ; Temporal Lobe* ; Tomography, Emission-Computed, Single-Photon*

No abstract available.
Brain* ; Tomography, Emission-Computed, Single-Photon*