[en] The magnetic property of a graphene-adsorbed Fe adatom was observed under an external electric field effect (−0.3–0.3 eV/Å) using density functional theory (DFT) calculations. In this study, it was demonstrated that the magnetic moment of Fe on graphene was changed linearly according to the electric field. The density of states and differential planar-averaged charge-density indicated that the changing electronic structure was due to a redistribution of valence electrons under external electric field that induces a continuous change in the localized magnetic moment of the Fe adatom. This research suggests that the magnetic property of the adatom on graphene is tunable by an electric field. Furthermore, these results may be applicable to the spintronic memory device industry. - Highlights: • E-field effect on the magnetic property of Fe/graphene was investigated. • Magnetic moment of Fe adatom changed continuously according to E-field. • Change in magnetic property is caused by the charge redistribution in Fe/graphene system. • Understanding of E-field effect offers a clear view for spintronics applications

[en] Since its introduction 20 years ago, nuclear cardiology in the Republic of Korea has grown impressively and is now widely used as a noninvasive procedure in the diagnosis and functional evaluation of various types of heart diseases. All of the classes of procedures, that is, first-pass radionuclide cardioangiography, gated blood pool scan, myocardial perfusion imaging, and myocardial infarct imaging, are being employed frequently and have been the subject of numerous studies. First-pass radionuclide ventriculography is being used in the detection and quantification of intracardiac shunts, the evaluation of chamber size, function, or cardiopulmonary dynamics in various disease states. With gated blood pool scans, several parameters of cardiac function are being measured in a variety of conditions including coronary heart disease. Quantifications of regurgitations are also being done. Both thallium-201 and technetium-99m pyrophosphate are being used in the diagnosis of coronary artery disease. Besides clinical imaging, active research in the field of nuclear cardiology has also been taking place in the Republic of Korea. Examples include investigations on new imaging agents such as ¹¹¹In-antimyosin monoclonal antibody and hexakis technetium(I) cations, or instrumental developments such as the nuclear stethoscope. Despite such noteworthy accomplishments, however, there have also been some obstacles to further developments in the Republic of Korea, such as the unavailability of a cyclotron. Nevertheless, considering the rate of expansion these procedures are showing and the effort we are putting into further development, the future for nuclear cardiology in the Republic of Korea appears quite promising and may become an example for other developing countries. (author). 28 refs, 5 figs, 2 tabs

[en] A ⁸²Sr/⁸²Rb generator was prepared by loading ⁸²Sr to preconditioned tin dioxide column. The generator was eluted by normal saline with flow rate up to 8 ml/min, and the eluted radioactivity was monitored by dose calibrator. Radioactivity began to come out at 5 ml and reached to peak around 9 ml. The total eluted radioactivity increased linearly with flow rate, and the maximum obtained radioactivity was 35mCi at 8 ml/min. The ⁸²Rb preparation was proven to be free from both strontium radioactivity and pyrogen. The ⁸²Rb was injected to normal female volunteer and positron emission tomographic image of heart was obtained successfully.

[en] Since angiostatin is a promising anticancer agent that target tumor endothelial cells, it may have advantages over many current tumor imaging agents by overcoming problems such as poor delivery or multi-drug resistance. We therefore synthesized radiolabeled agniostatin and tested it in vivo. ¹²³-angiostatin was synthesized using the Bolton Hunter method. ¹²³I labeled plasminogen lysin-binding-site (LBS) was also synthesized. Blood clearance of he radiotracer was measured in SD rats, while tissue distribution was assessed in ICR mice at 1,4, and 18 hr. Pinhole scintigraphy was performed in SD rats and in nude mice bearing RR 1022 tumors at various time points. Radiochemical yield of ¹²³I-angiostatin approximated 20%. In vivo distribution demonstrated stability of the label for at least 20 hr. ¹²³I-angiostatin was cleared from the circulation in a biexponential manner with rapid early clearance followed by a slower rate of elimination Tissue distribution in mice showed the highest uptake in the kidneys which was the major route of excretion. This was followed by the lung, liver, and myocardium whose uptake of 1.5∼2% ID/gm at 1 hrs gradually decreased over time (all p<0.05). Skeletal muscle uptake was relatively low (<0.3 %ID/gm). ¹²³I-angiostatin and ¹²³I-LBS images in SD rates showed a similar distribution. Blood pool activity gradually cleared while tumor uptake increased over time, resulting in a high tumor to non tumor ratio at 20 hr. ¹²³I-angiostatin has promising potential as a new tumor imaging agent. Further study is warranted to assess its mechanism of uptake and precise role in cancer imaging

[en] The localization of extratemporal neocortical epileptogenic foci is more difficult than that of temporal lobe epilepsy. The purpose of the study was to evaluated the usefulness of ictal single photon emission computed tomography (SPECT) compared with ictal electroencephalogram (EEG) and magnetic resonance imaging (MRI) findings in this group of patients. Twenty-three patients diagnosed as having intractable focal epilepsy of neocortical origin were evaluated with ictal ⁹⁹Tc^m-HMAPO (hexamethylpropylene amine oxime) SPECT, video EEG monitoring and MRI. The final epileptogenic foci were considered as determined when either all three tests were concordant or two tests were in agreement while the remaining was non-lateralizing. The final epileptogenic focus was in the frontal lobe in eight patients, lateral temporal in six, parietal in three, occipital in three and undetermined in three patients. Of the 20 patients whose epiloptogenic focus was determined, ictal SPECT and ictal EEG correctly localized the focus in 17 (85%) patients, while MRI showed correct localization in seven (35%) cases. Of the 13 patients non-localized with MRI, ictal SPECT showed regional hyperperfusion in 12 patients. Thus, ictal SPECT was highly accurate in localizing epileptogenic foci in neocortical epilepsy patients and appeared particularly useful in cases with non-lateralizing ictal EEG or MRI. (author). 10 refs, 2 figs, 1 tab

[en] Objective: Previous studies reported that CT-based measured attenuation correction (CT-MAC) produced radioactivity concentration values significantly higher than 68Ge- based segmented attenuation correction (Ge-SAC) in PET images. However, it was unknown whether the radioactivity concentration difference resulted from different sources (CT vs. Ge) or types (MAC vs. SAC) of AC. We evaluated the influences of the source and type of attenuation correction on the radioactivity concentration differences between reconstructed PET images. Methods: FDG PET images were acquired with a human thoracic phantom, 4 Spargue-Dawley rats (∼300 g) bearing sarcoma transplanted in right inguinal area and 5 normal human subjects (4 male and 1 female; 29.4±2.5 yr) using a combined PET/CT scanner (Discovery LS, GE). In each subject, CT images (140 KeV, 40∼80 mAs) were acquired, and then emission (5-min/bed) and post-injection 68Ge-transmission (3-min/bed) scan was performed. Attenuation corrected PET images using OSEM algorithm (28 subsets, 2 iterations) were reconstructed by 4 methods: CT-MAC, CT-SAC, Ge-MAC, and CT-SAC. Identical regions-of-interest (ROIs) were placed over the same locations in the 4 PET images of each study, and the mean values of ROIs were compared between the PET images. Results: In thoracic phantom images, the mean values of lung, liver and chest wall ROIs were highest in CT-MAC images (difference range: 3.6∼19.8%) followed by CT-SAC, Ge-SAC and Ge-MAC (mean relative uptake ratio - 114.4 : 110.3 : 108.1 : 100.2). The difference was smallest between CT-SAC and Ge-SAC images (difference range: 0.2∼5.1%). In rat images, the mean values of tumor and background ROIs were highest in CT-MAC images (difference range: 3.0∼14.1%) followed by CT-SAC, Ge-SAC and Ge-MAC (mean relative uptake ratio - 110.6 : 103.6 : 103.0 : 100.1). The difference was smallest between CT-SAC and Ge-SAC images (difference range: -5.0∼3.4%). In human subjects, the mean values of ROIs in 18 organs except lung, tonsil and fat tissue were highest in CT-MAC images (difference range: -3.5∼16.7%) followed by CT-SAC, Ge-SAC and Ge-MAC (mean SUV ratio - 6.12 : 5.94 : 5.88 : 5.88). The % differences between CT-SAC and Ge-SAC, and Ge-SAC and Ge-MAC images were -5.1∼11.0% and -14.7∼6.7%, respectively. Conclusions: Quantitative radioactivity values in CT-MAC PET images were higher than those in CT-SAC, Ge-SAC and Ge-MAC PET images. Both source (CT vs. Ge) and type (MAC vs. SAC) of AC may contribute to those differences. (authors)

[en] In uterine cervical cancer, it is clinically important to predict prognosis on initial staging. We investigated whether abnormally increased FDG uptake of lymph nodes and peak SUV of primary tumor on initial FDG PET can predict prognosis after treatment in cervical patients. Subjects were 74 newly diagnosed cervical cancer patients (50±12yr). Whole body PET was performed after an injection of F-18 FDG. Peak SUV was measured in the primary cervical tumor. Images were interpreted by two nuclear medicine physicians. Follow-up for the disease-free survival was done in all patients. Survival analysis was done by using the Kaplan-Meier method, and a Logrank test was used to compare survival. Cox regression analysis was followed to find independent predictive factors. Recurrence occurred in 13 patients. In univariate analysis, advanced FIGO stage, large size of primary tumor, positive lymph node on MRI of CT, and positive lymph node on PET were significant prognostic factors to predict recurrence. Peak SUV and cell type of tumor failed to show any significant correlation with disease-free survival. In multivariate analysis, positive lymph node on PET (Exp(β)=6.416, p=0.002) and on CT or MRI (Exp(β)=5.711, p=0.026) were independent prognostic factors for predicting recurrence. In uterine cervical cancer, lymph node metastasis of pretreatment FDG PET is the best independent prognostic factor for predicting recurrence. But, peak SUV was not significant prognostic factor

[en] Brain perfusion SPECT shows typical regional perfusion abnormalities in Alzheimer's disease(AD) and is useful for its diagnosis. However, there is also argument that these patterns show significant overlap with other causes, and the accuracy for SPECT in differentiating AD has shown conflicting results. We postulate that the variation in reported results are partly due to a difference in patient or control selection with specia reference to the mixture of ischemic cerebral disease in the studied population. To determine the effect of ischemic lesions and the nature of control subjects on SPECT studies for AD, we performed ^99mTc-HMPAO single photon emission computed tomography(SPECT) in 11 probable AD patients with a low (<4) Hachinski ischemic score and 12 non-demented age matched controls. Magnetic resonance imaging(MRI) disclosed ischemic cerebral lesions in 27%(3/11) of the PAD group and 25%(3/12) of the control group. Regional perfusion indices were quantitated from the SPECT images as follows and the distribution of perfusion indices from both groups were compared. This was repeated with controls after excluding those with significant ischemic lesions by MRI: regional perfusion index=average regional count/average cerebellar count All PAD patients showed perfusion abnormality in SPECT. However, 83% (10/12)of controls also showed perfusion abnormalities, and no pattern could reliably differentiate the two groups. After excluding controls with significant cerebral ischemia, the difference in temporal and parietal perfusion index was increased. A decreased temporo-parietal and any parietal or temporal perfusion index had a sensitivity of 18% and 36% in detecting AD, respectively. When using a separate group of normal age matched controls, the indices showed an even more difference in the temporal and parietal lobes and the sensitivity of a decreased temporoparietal and any parietal or temporal perfusion index had a sensitivity of 36% and 55% in detecting AD, respectively. Thus, the type of control with special reference to the presence of ischemic cerebral lesions contribute significantly to the accuracy of perfusion SPECT in diagnosing AD. This may have particular importance in the diagnosis of AD in populations where the prevalance of cerebrovascular disease in high.

[en] Tc-99m-MIBI(Sestamibi) myocardial SPECT along with T1-201 tomographic imaging has demonstrated wide application and high image quality sufficient for the diagnosis of myocardial perfusion defect, which consequently reflects regional myocardial blood flow. The qualitative values of myocardial SPECT with Tc-99m-MIBI as well as the quantitative cases depend in some degree on the reconstruction techniques of multiple projections. Filtered backprojection(FBP) is the common standard for reconstruction rather than the complicated and time-consuming arithmetic methods. In FBP it is known that the distribution of radioactivity in reconstructed transverse slices varies with the selected filter parameters such as cutoff frequencies and order (Butterworth case). The cutoff frequencies basically remove and decrease the true radioactive distribution and alter the pixel counts, which lead to underestimation of true counts in specific myocardial regions. In this study, we have investigated the effect of cutoff frequencies of reconstruction filter on the artifactually induced perfusion defects, which are often demonstrated near inferior and/or inferoseptal cardiac walls due to the intense hepatic uptake of Tc-99m-MIBI. A computerized method for identifying the relative degree of artifactual perfusion defect and for comparing those degrees along with the relative amount of hepatic uptake to myocardium was developed and patient images were studied to observe the quantitative degree of underestimation of myocardial perfusion, and to propose some reasonable thresh-old of cutoff frequency in the diagnosis of perfusion defect quantitatively. We concluded that from the quantitative viewpoint cutoff frequencies may be used as high as possible with the sacrifice of homogeneity of image quality, and those frequencies lower than the common 0.3 Nyquist frequency would reveal severe degradation of radio-active distribution near inferior and/or inferoseptal myocardium when applying Butterworth or low pass filter.

[en] Encephalo-duro-arterio-synangiosis (EDAS) is a relatively new surgical procedure for treatment of childhood moyamoya disease. We assessed regional cerebral perfusion in moyamoya patients before (1.3 mo) and after (6.8 mo) EDAS with ^99mTc-HMPAO brain SPECT. A total of 21 EDAS operations in 17 moyamoya patients was included. Preoperative CT or MRI showed cerebral infarction in 14 patients and carotid angiography showed Suzuki grade 1 to V stenosis in 6%, 9%, 62%, 12% and 12% of the hemispheres respectively. Preoperative SPECT showed regional hypoperfusion in all patients, bilateral frontal and temporal loves being the most frequently involved site. 4 X 4 pixel sized ROIs were applied on the frontotemmporal cortex in 3 slice averaged transverse tomographic images. An index of regional perfusion was measured as; PI (%)=average FT activity/average cerebellar activity X 100 Pre-EDAS ipsilateral PI ranged from 23.7 to 98.4% (mean:74.3 ± 17%) and increased significantly after operation (81.4 ± 17%, p<0.001). Individual post-EDAS PI improved in 15/21 cases, showed no significant change in 5 and was slightly aggravated in 1. The amount of clinical improvement XCI) was graded with a scale of 0 to 4 based on frequency and severity of TIA attacks. When patients were grouped according to pre-EDAS PI, group II (PI 70∼89) showed a significantly higher CI (3.3) compared to group I (PI<70, 1.57) of group III (PI>90, 0.5) (p<0.001). The amount of perfusion improvement (PI) showed significant correlation with CI (r-0.42, p=0.04). PI did not, however, correlate with the amount of neovascularization assessed angiographically in 8 patients. Serial HMPAO SPECT is an useful noninvasive study for assessing perfusion improvement after EDAS in childhood moyamoya patients.