Dae-Weung Kim

Detecting the Recurrence of Gastric Cancer after Curative Resection: Comparison of FDG PET/CT and Contrast-Enhanced Abdominal CT

The purpose of this study was to evaluate the value of fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT) for detecting the recurrence of gastric cancer. We performed a retrospective review of 139 consecutive patients who underwent PET/CT and contrast-enhanced abdominal CT (CECT) for surveillance of gastric cancer after curative resection. Recurrence of gastric cancer was validated by histopathologic examination for local recurrence or serial imaging study follow-up with at least 1 yr interval for recurrence of distant metastasis form. Twenty-eight patients (20.1%) were confirmed as recurrence. On the patient based analysis, there was no statistically significant difference in the sensitivity, specificity and accuracy of PET/CT (53.6%, 84.7%, and 78.4%, respectively) and those of CECT (64.3%, 86.5%, and 82.0%, respectively) for detecting tumor recurrence except in detection of peritoneal carcinomatosis. Among 36 recurrent lesions, 8 lesions (22.2%) were detected only on PET/CT, and 10 lesions (27.8%) only on CECT. PET/CT had detected secondary malignancy in 8 patients. PET/CT is as accurate as CECT in detection of gastric cancer recurrence after curative resection, excepting detection of peritoneal carcinomatosis. Moreover, additional PET/CT on CECT could improve detection rate of tumor recurrence and provide other critical information such as unexpected secondary malignancy.

The efficacy of dual time point F-18 FDG PET imaging for grading of brain tumors.

Purpose: Several studies have explored the usefulness of dual time point F-18 FDG positron emission tomography imaging (DTPI) in improving detection of brain metastases and tumors outside the brain, distinguishing malignant from benign. In the same manner, DTPI may show better performance to grade of brain tumors. Methods: Twenty-two lesions of 18 consecutive patients with primary or metastatic brain tumor were included prospectively. DTPI was performed and analyzed using maximum standardized uptake values (SUVmax), mean standardized uptake values within isocontour at 70% of maximum pixel values (SUViso), and retention index (RI) for each lesion. Results: SUVmax and SUViso of the delayed image were more efficient than those of early images to classify lesions by the grade of tumors. The RI of SUVmax and SUViso were not significant to classify lesions. Conclusion: DTPI may be a better imaging method to grade the brain tumor than early imaging only.

Synthesis and evaluation of novel Tc-99 m labeled NGR-containing hexapeptides as tumor imaging agents

Asparagine-glycine-arginine (NGR)-containing peptides targeting aminopeptidase N (APN)/CD13 can be an excellent candidate for targeting ligands in molecular tumor imaging. In this study, we developed two NGR-containing hexapeptides, and evaluated the diagnostic performance of Tc-99m labeled hexapeptides as molecular imaging agents in an HT-1080 fibrosarcoma-bearing murine model. Peptides were synthesized using Fmoc solid-phase peptide synthesis. Radiochemical purity of Tc-99m was evaluated using instant thin-layer chromatography. The uptake of two NGR-containing hexapeptides within HT-1080 cells was evaluated in vitro. In HT-1080 fibrosarcoma tumor-bearing mice, gamma images were acquired. A biodistribution study was performed to calculate percentage of the injected dose per gram of tissue (%ID/g). Two hexapeptides, glutamic acid-cysteine-glycine (ECG)-NGR and NGR-ECG were successfully synthesized. After radiolabeling procedures with Tc-99m, the complexes Tc-99m hexapeptides were prepared in high yield. The uptake of Tc-99m ECG-NGR within the tumor cells had been assured by in vitro studies. The gamma camera imaging in the murine model showed that Tc-99m ECG-NGR was accumulated substantially in the subcutaneously engrafted tumor. However, Tc-99m NGR-ECG was accumulated minimally in the tumor. Two NGR-containing hexapeptides, ECG-NGR and NGR-ECG were developed as molecular imaging agents to target APN/CD13 in HT-1080 fibrosarcoma. Tc-99m ECG-NGR showed a significant uptake in the tumor, and it is a good candidate for tumor imaging.

Novel Tc-99m labeled ELR-containing 6-mer peptides for tumor imaging in epidermoid carcinoma xenografts model: a pilot study

ObjectiveELR-containing peptides targeting CXCR2 could be the excellent candidate for targeting ligand of molecular tumor imaging. In this study, we had developed two ELR-containing 6-mer peptides and evaluated the diagnostic performance of Tc-99m labeled 6-mer peptides as a molecular imaging agent in murine models bearing KB epidermoid carcinoma.MethodsPeptides were synthesized using Fmoc solid phase peptide synthesis. Radiolabeling efficiency with Tc-99m was evaluated using instant thin-layer chromatography. In KB epidermoid cancer-bearing mice, gamma images had acquired and tumor-to-muscle uptake ratio was calculated. Competition and biodistribution studies had performed.ResultsTwo 6-mer peptides, ELR-ECG and ECG-ELR were successfully synthesized. After radiolabeling procedures with Tc-99m, the complex Tc-99m ELR-ECG and Tc-99m ECG-ELR were prepared in high yield. In the gamma camera imaging of murine model, Tc-99m ELR-ECG was substantially accumulated in the subcutaneously engrafted tumor and tumor uptake had been suppressed by the free ELR co-injection. However, Tc-99m ECG-ELR was minimally accumulated in the tumor.ConclusionsTwo ELR-containing 6-mer peptides, ELR-ECG and ECG-ELR, were developed as a molecular imaging agent to target CXCR2 of epidermoid carcinoma. Tc-99m ELR-ECG had showed significant uptake in tumor and it was good candidate for a tumor imaging.

Dual-time-point positron emission tomography findings of benign mediastinal fluorine-18-fluorodeoxyglucose uptake in tuberculosis-endemic region

Background: We performed dual-time-point positron emission tomography imaging in patients without evidences of mediastinal lymph node metastasis to investigate the characteristics of benign mediastinal fluorine-18-fluorodeoxyglucose (FDG) uptake. Materials and Methods: One-hundred and eighteen mediastinal lesions of 24 patients were included for this study. On the early and delayed positron emission tomography images, size, attenuation, maximum standardized uptake value (SUV) and retention indices (RI) were recorded for lymph node characterization. Results: The mean SUV on the early and delayed scan of 118 lymph nodes was 3.3±1.2 and 4.2±1.7, respectively. The mean RI was 26.4±24.5%. Higher FDG uptake was observed in patients with calcified nodules and bilateral FDG uptake and in lymph nodes with calcification or short-axis diameter larger than 10 mm. Conclusion: In tuberculosis-endemic area, the increments of SUV or RI were frequently observed in benign mediastinal lymph nodes, and these values might not be the accurate indicators of malignant disease for mediastinal FDG uptake.

Radiolabeled Chitosan Hydrogel Containing VEGF Enhances Angiogenesis in a Rodent Model of Acute Myocardial Infarction

Vascular endothelial growth factor (VEGF) plays a pivotal role in angiogenesis in an infarcted myocardium. The purpose of the current investigation was to validate whether a radiolabeled VEGF delivery system can be effectively monitored in vivo, and to ascertain whether the growth factor induces an angiogenic effect to facilitate recovery from infarct conditions in rodent myocardial infarction (MI) models. Rat MI models were divided into three groups, one with left anterior descending coronary artery (LAD) ligation with no injection (the control group), one with LAD ligation and I-131 VEGF injection (the VEGF group), and one with LAD ligation and I-131 VEGF-loaded chitosan injection (the VIC group). On day 7 after injection, autoradiography imaging was performed, followed by semiquantitative and histopathologic analyses. In semi-quantitative analysis, the mean anterior-to-inferior wall ratio of the VIC group was significantly higher than those of the control and VEGF groups (p<0.05). Histopathologic experiments revealed a marked increase in microvascular density in the VIC group compared to those of the control and VEGF groups (p<0.05). Intramyocardially injected VIC was not only effectively monitored in vivo, but also stimulated therapeutic angiogenesis in the infarcted myocardium. Our findings support that the developed VIC is a novel theranostic tool to improve myocardial perfusion following myocardial infarction.

Synthesis and evaluation of Tc-99m-labeled RRL-containing peptide as a non-invasive tumor imaging agent in a mouse fibrosarcoma model.

ObjectiveArginine–arginine–leucine (RRL) is considered a tumor endothelial cell-specific binding sequence. RRL-containing peptide targeting tumor vessels is an excellent candidate for tumor imaging. In this study, we developed RRL-containing hexapeptides and evaluated their feasibility as a tumor imaging agent in a HT-1080 fibrosarcoma-bearing murine model.MethodsThe hexapeptide, glutamic acid–cysteine–glycine (ECG)–RRL was synthesized using Fmoc solid-phase peptide synthesis. Radiolabeling efficiency was evaluated using instant thin-layer chromatography. Uptake of Tc-99m ECG–RRL within HT-1080 cells was evaluated in vitro by confocal microscopy and cellular binding affinity was calculated. Gamma images were acquired In HT-1080 fibrosarcoma tumor-bearing mice, and the tumor-to-muscle uptake ratio was calculated. The inflammatory-to-normal muscle uptake ratio was also calculated in an inflammation mouse model. A biodistribution study was performed to calculate %ID/g.ResultsA high yield of Tc-99m ECG–RRL complexes was prepared after Tc-99m radiolabeling. Binding of Tc-99m ECG–RRL to tumor cells had was confirmed by in vitro studies. Gamma camera imaging in the murine model showed that Tc-99m ECG–RRL accumulated substantially in the subcutaneously engrafted tumor and that tumoral uptake was blocked by co-injecting excess RRL. Moreover, Tc-99m ECG–RRL accumulated minimally in inflammatory lesions.ConclusionsWe successfully developed Tc-99m ECG–RRL as a new tumor imaging candidate. Specific tumoral uptake of Tc-99m ECG–RRL was evaluated both in vitro and in vivo, and it was determined to be a good tumor imaging candidate. Additionally, Tc-99m ECG–RRL effectively distinguished between cancerous tissue and inflammatory lesions.

Optical absorption spectra of undoped and Co-doped Cd4GeSe6 single crystals

The ternary semiconducting compounds of A4BX 6 type ( A = C d , Hg, B = S i , Ge and X = S , Se) exhibit high photosensitivity and strong luminescence in the visible and near-infrared regions [1-4]. These desirable properties make the compounds promising optoelectronic materials. However, not many studies have been made on these compounds because of considerable difficulties in obtaining homogeneous and stoichiometric crystals. Among the few studies undertaken, some attention has been paid to crystal growth [5], photoconductivity [2, 4] and photoluminescence [3] of CdeSiS 6 and Cd4GeSe6. Quenez and Gorochov [6] have reported on the crystal growth of Cd4GeSe6 by the chemical transport technique using iodine, bromide and chlorine as transporting agents. In earlier work [7], the authors have investigated photoluminescence spectra of Cd4GeSe6 crystals. However, the temperature dependence of the optical energy gap in the CdeGeSe6 compound has not been investigated to date. No study of the optical properties of transition metal impurities in this compound has been made. The purpose of the present letter is to report on the temperature dependence of the optical energy gaps of undoped and Co-doped Cd4GeSe6 single crystals grown by the chemical transport technique. The effects of the doping of the cobalt transition metal impurity on the optical absorption of this compound are also studied. Single crystals of Cd4GeSe 6 and Cd4GeSe6:Co (2 mol %) were grown by the chemical transport technique using iodine as a transporting agent. The starting materials were powders of polycrystalline Cd4GeSe 6 and Cd4GeSe6:Co [7] prepared by reacting stoichiometric quantities of cadmium (99.9999% purity), germanium (99.9999% purity), selenium (99.9999% purity) and cobalt (99.99% purity) in an evacuated quartz ampoule using a rotating horizontal furnace. The amount of iodine was 5 mg per cm 3 ampoule volume. The charged ampoule was evacuated to 2 x 10 -6 mmHg and the sealed ampoule was placed in a two-zone furnace with the source zone temperature 580 °C and the growth zone

Experience of Dual Time Point Brain F-18 FDG PET/CT Imaging in Patients with Infectious Disease

Dual time point FDG PET imaging (DTPI) has been considered helpful for discrimination of benign and malignant disease, and staging lymph node status in patients with pulmonary malignancy. However, DTPI for benign disease has been rarely reported, and it may show a better description of metabolic status and extent of benign infectious disease than early imaging only. The authors report on the use F-18 fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT) imaging with additional delayed imaging on a 52-year-old man with sparganosis and a 70-year-old man with tuberculous meningitis. To the best of our knowledge, this is the first report on dual time point PET/CT imaging in patients with cerebral sparganosis and tuberculous meningitis.

Gating error because of prominent T waves with ECG-gated myocardial SPECT.

It was well known that with marked arrhythmias, gating errors may produce perfusion and wall motion abnormalities. In the present case, without any arrhythmias or perfusion defects, severe abnormalities of wall contraction and thickening were demonstrated because of prominent T waves. This gating error was easily corrected by changing guidance lead to increase the amplitude of the R wave and decrease that of the T wave.