PURPOSE: We compared the reproducibility of 201Tl and 99mTc-sestamibi (MIBI) gated SPECT measurement of myocardial function using the Germano algorithm. MATERIALS AND METHODS: Gated SPECT acquisition was repeated in the same position in 30 patients who received 201Tl and in 26 who received 99mTc-MIBI. The quantification of end-diastolic volume (EDV), end-systolic volume (ESV), and ejection fraction (EF) on 201Tl and 99mTc-MIBI gated SPECT was processed independently using Cedars quantitative gated SPECT software. The reproducibility of the assessment of myocardial function on 201Tl gated SPECT was compared with that of 99mTc-MIBI gated SPECT. RESULTS: Correlation between the two measurements for volumes and EF was excellent by the repeated gated SPECT studies of 201Tl (r=0.928 to 0.986; p<0.05) and 99mTc-MIBI (r=0.979 to 0.997; p<0.05). However, Bland Altman analysis revealed the 95% limits of agreement (2 SD) for volumes and EF were tighter by repeated 99mTc-MIBI gated SPECT (EDV: 14.1 ml, ESV: 9.4 ml and EF: 5.5%) than by repeated 201Tl gated SPECT (EDV: 24.1 ml, ESV: 18.6 ml and EF: 10.3%). The root mean square (RMS) values of the coefficient of variation (CV) for volumes and EFs were smaller by repeated 99mTc-MIBI gated SPECT (EDV: 2.1 ml, ESV: 2.7 ml and EF: 2.3%) than by repeated 201Tl gated SPECT (EDV: 3.2 ml, ESV: 3.5 ml and EF: 5.2%). CONCLUSION: 99mTc-MIBI provides more reproducible volumes and EF than 201Tl on repeated acquisition gated SPECT. 99mTc-MIBI gated SPECT is the preferable method for the clinical monitoring of myocardial function.
Humans ; Perfusion* ; Technetium Tc 99m Sestamibi ; Tomography, Emission-Computed, Single-Photon*

PURPOSE: Thallim-201 (201Tl) brain SPECT, which can represent cellular activity of brain lesions, may provide more useful information in differentiating between benign and malignant brain lesions more so than CT or MRI, that merely represents anatomic changes or breakdown of blood brain barrier. We used 201Tl brain SPECT prospectively to evaluate the utility of 201Tl-indices as an indicator of benign or malignant lesions. MATERIALS AND METHODS: We studied 28 patients. There were 13 cases of benign lesions (3: nonspecific benign lesion, 3: meningioma, 2: low grade glioma, 1: tuberculoma, central neurocytoma, hemangioblastoma, radiation necrosis, and choroid plexus papilloma) and 15 cases of malignant lesions (6: glioblastoma multiforme, 5: anaplastic glioma, 2: medulloblastoma, 1: metastasis and lymphoma). In all patients, CT and/or MRI were obtained and then 201Tl brain SPECT was obtained with measuring mean 201Tl index and peak 201Tl index. An unpaired t-test was performed to compare the 201Tl-indices and pathologic diagnoses to evaluate the utility of 201Tl-indices as an indicator of benign or malignant lesions. RESULTS: There were no statistically significant difference in 201Tl-indices between benign and malignant brain lesions (P>0.05). CONCLUSION: These results demonstrated that we could not use 201Tl indices on brain SPECT alone as an indicator of benign or malignant brain lesions.
Blood-Brain Barrier ; Brain* ; Choroid Plexus ; Diagnosis ; Glioblastoma ; Glioma ; Hemangioblastoma ; Humans ; Magnetic Resonance Imaging ; Medulloblastoma ; Meningioma ; Necrosis ; Neoplasm Metastasis ; Neurocytoma ; Prospective Studies ; Tomography, Emission-Computed, Single-Photon* ; Tuberculoma

Molecular imaging is a rapidly growing field due to the advances in molecular biology and imaging technologies. With the introduction of imaging reporter genes into the cell, diverse cellular processes can be monitored, quantified and imaged non-invasively in vivo. These processes include the gene expression, protein-protein interactions, signal transduction pathways, and monitoring of cells such as cancer cells, immune cells, and stem cells. In the near future, molecular imaging analysis will allow us to observe the incipience and progression of the disease. These will make us easier to give a diagnosis in the early stage of intractable diseases such as cancer, neuro-degenerative disease, and immunological disorders. Additionally, molecular imaging method will be a valuable tool for the real-time evaluation of cells in molecular biology and the basic biological studies. As newer and more powerful molecular imaging tools become available, it will be necessary to corporate clinicians, molecular biologists and biochemists for the planning, interpretation, and application of these techniques to their fullest potential. In order for such a multidisciplinary team to be effective, it is essential that a common understanding of basic biochemical and molecular biologic techniques is achieved. Basic molecular techniques for molecular imaging methods are presented in this paper.
Cloning, Organism ; Diagnosis ; Gene Expression ; Genes, Reporter ; Molecular Biology ; Molecular Imaging* ; Polymerase Chain Reaction ; Signal Transduction ; Stem Cells

Molecular imaging provides a visualization of normal as well as abnormal cellular processes at a molecular or genetic level rather than at a anatomical level. Conventional medical imaging methods utilize the imaging signals produced by nonspecific physico-chemical interaction. However, molecular imaging methods utilize the imaging signals derived from specific cellular or molecular events. Because molecular and genetic changes precede anatomical change in the course of disease development, molecular imaging can detect early events in disease progression. In the near future, through molecular imaging we can understand basic mechanisms of disease, and diagnose earlier and, subsequently, treat earlier intractable diseases such as cancer, neuro-degenerative diseases, and immunologic disorders. In beginning period, nuclear medicine started as a molecular imaging, and has had a leading role in the field of molecular imaging. But recently molecular imaging has been rapidly developed. Besides nuclear imaging, molecular imaging methods such as optical imaging, magnetic resonance imaging are emerging. Each imaging modalities have their advantages and weaknesses. The opportunities from molecular imaging look bright. We should try nuclear medicine continues to have a leading role in molecular imaging.
Diagnostic Imaging ; Disease Progression ; Genes, Reporter ; Magnetic Resonance Imaging ; Molecular Imaging ; Nuclear Medicine ; Optical Imaging

PURPOSE: NEMA NU2-2001 was proposed as a new standard for performance evaluation of whole body PET scanners. In this study, system performance of Siemens CTI ECAT EXACT 47 PET scanner including spatial resolution, sensitivity, scatter fraction, and count rate performance in 2D and 3D mode was evaluated using this new standard method. METHODS: ECAT EXACT 47 is a BGO crystal based PET scanner and covers an axial field of view (FOV) of 16.2 cm. Retractable septa allow 2D and 3D data acquisition. All the PET data were acquired according to the NEMA NU2-2001 protocols (coincidence window: 12 ns, energy window: 250 ~ 650 keV). For the spatial resolution measurement, F-18 point source was placed at the center of the axial FOV ( (a) x=0, and y=1, (b) x=0, and y=10, (c) x=10, and y=0cm) and a position one fourth of the axial FOV from the center ( (a) x=0, and y=1, (b) x=0, and y=10, (c) x=10, and y=0cm). In this case, x and y are transaxial horizontal and vertical, and z is the scanner's axial direction. Images were reconstructed using FBP with ramp filter without any post-processing. To measure the system sensitivity, NEMA sensitivity phantom filled with F-18 solution and surrounded by 1~5 aluminum sleeves were scanned at the center of transaxial FOV and 10 cm offset from the center. Attenuation free values of sensitivity were estimated by extrapolating data to the zero wall thickness. NEMA scatter phantom with length of 70 cm was filled with F-18 or C-11solution (2D: 2, 900 MBq, 3D: 407 MBq), and coincidence count rates were measured for 7 half-lives to obtain noise equivalent count rate (NECR) and scatter fraction. We confirmed that dead time loss of the last frame were below 1%. Scatter fraction was estimated by averaging the true to background (scatter + random) ratios of last 3 frames in which the fractions of random rate are negligibly small. RESULTS: Axial and transverse resolutions at 1cm offset from the center were 0.62 and 0.66 cm (FBP in 2D and 3D), and 0.67 and 0.69 cm (FBP in 2D and 3D). Axial, transverse radial, and transverse tangential resolutions at 10cm offset from the center were 0.72 and 0.68 cm (FBP in 2D and 3D), 0.63 and 0.66 cm (FBP in 2D and 3D), and 0.72 and 0.66 cm (FBP in 2D and 3D). Sensitivity values were 708.6 (2D), 2931.3 (3D) counts/sec/MBq at the center and 728.7 (2D), 3398.2 (3D) counts/sec/MBq at 10 cm offset from the center. Scatter fractions were 0.19 (2D) and 0.49 (3D). Peak true count rate and NECR were 64.0 kcps at 40.1 kBq/mL and 49.6 kcps at 40.1 kBq/mL in 2D and 53.7 kcps at 4.76 kBq/mL and 26.4 kcps at 4.47 kBq/mL in 3D. CONCLUSION: Information about the performance of CTI ECAT EXACT 47 PET scanner reported in this study will be useful for the quantitative analysis of data and determination of optimal image acquisition protocols using this widely used scanner for clinical and research purposes.
Aluminum ; Architectural Accessibility ; Noise

PURPOSE: Chitosan has been studied as a non-viral gene delivery vector, drug delivery carrier, metal chelater, food additive, and radiopharmaceutical, among other things. Recently, galactose-graft chitosan was studied as a non-viral gene and drug delivery vector to target hepatocytes. The aim of this study was to investigate the usefulness of nuclear imaging for in vivo evaluation of targeting the hepatocyte by galactose grafting. METHODS AND MATERIALS: Galactosyl methylated chitosan (GMC) was produced by methylation to lactobionic acid coupled chitosan. Cytotoxicity of 99mTc-GMC was determined by MTT assay. Rabbits were injected via their auricular vein with 99mTc-GMC and 99mTc-methylated chitosan (MC), the latter of which does not contain a galactose group, and images were acquired with a gamma camera equipped with a parallel hole collimator. The composition of the galactose group in galactosylated chitosan (GC), as well as the tri-, di-, or mono-methylation of GMC, was confirmed by NMR spectroscopy. RESULTS: The results of MTT assay indicated that 99mTc-GMC was non-toxic. 99mTc-GMC specifically accumulated in the liver within 10 minutes of injection and maintained high hepatic uptake. In contrast, 99mTc-MC showed faint liver uptake. 99mTc-GMC scintigraphy of rabbits showed that the galactose ligand principally targeted the liver while the chitosan functionalities led to excretion through the urinary system. CONCLUSION: Bioconjugation with a specific ligand endows some degree of targetability to an administered molecule or drug, as in the case of galactose for hepatocyte in vivo, and evaluating said targetabililty is a clear example of the great benefit proffered by nuclear imaging.
Chitosan* ; Food Additives ; Galactose ; Gamma Cameras ; Hepatocytes ; Liver ; Magnetic Resonance Spectroscopy ; Methylation ; Rabbits ; Radionuclide Imaging ; Transplants ; Veins

PURPOSE: Population based structural and functional maps of the brain provide effective tools for the analysis and interpretation of complex and individually variable brain data. Brain MRI and PET standard templates and statistical probabilistic maps based on image data of Korean normal volunteers have been developed and probabilistic maps based on cytoarchitectonic data have been introduced. A quantification method using these data was developed for the objective assessment of regional intensity in the brain images. Materials and METHODS: Age, gender and ethnic specific anatomical and functional brain templates based on MR and PET images of Korean normal volunteers were developed. Korean structural probabilistic maps for 89 brain regions and cytoarchitectonic probabilistic maps for 13 Brodmann areas were transformed onto the standard templates. Brain FDG PET and SPGR MR images of normal volunteers were spatially normalized onto the template of each modality and gender. Regional uptake of radiotracers in PET and gray matter concentration in MR images were then quantified by averaging (or summing) regional intensities weighted using the probabilistic maps of brain regions. Regionally specific effects of aging on glucose metabolism in cingulate cortex were also examined. RESULTS: Quantification program could generate quantification results for single spatially normalized images per 20 seconds. Glucose metabolism change in cingulate gyrus was regionally specific: ratios of glucose metabolism in the rostral anterior cingulate vs. posterior cingulate and the caudal anterior cingulate vs. posterior cingulate were significantly decreased as the age increased. 'Rostral anterior'/ 'posterior' was decreased by 3.1% per decade of age (P< 10 (-11), r=0.81) and 'caudal anterior'/ 'posterior' was decreased by 1.7% (P< 10 (-8), r=0.72). CONCLUSION: Ethnic specific standard templates and probabilistic maps and quantification program developed in this study will be useful for the analysis of brain image of Korean people since the difference in shape of the hemispheres and the sulcal pattern of brain relative to age, gender, races, and diseases cannot be fully overcome by the nonlinear spatial normalization techniques.
Aging ; Brain* ; Continental Population Groups ; Glucose ; Gyrus Cinguli ; Healthy Volunteers ; Humans ; Magnetic Resonance Imaging ; Metabolism ; Tomography, Emission-Computed, Single-Photon

PURPOSE: We developed a computer-aided classifier using artificial neural network (ANN) to discriminate the cerebral metabolic pattern of medial and lateral temporal lobe epilepsy (TLE). Materials and METHODS: We studied brain F-18-FDG PET images of 113 epilepsy patients sugically and pathologically proven as medial TLE (left 41, right 42) or lateral TLE (left 14, right 16). PET images were spatially transformed onto a standard template and normalized to the mean counts of cortical regions. Asymmetry indices for predefined 17 mirrored regions to hemispheric midline and those for medial and lateral temporal lobes were used as input features for ANN. ANN classifier was composed of 3 independent multi-layered perceptrons (1 for left/right lateralization and 2 for medial/lateral discrimination) and trained to interpret metabolic patterns and produce one of 4 diagnoses (L/R medial TLE or L/R lateral TLE). Randomly selected 8 images from each group were used to train the ANN classifier and remaining 81 images were used as test sets. The accuracy of the diagnosis with ANN was estimated by averaging the agreement rates of independent 50 trials and compared to that of nuclear medicine experts. RESULTS: The accuracy in lateralization was 89% by the human experts and 90% by the ANN classifier. Overall accuracy in localization of epileptogenic zones by the ANN classifier was 69%, which was comparable to that by the human experts (72%). CONCLUSION: We conclude that ANN classifier performed as well as human experts and could be potentially useful supporting tool for the differential diagnosis of TLE.
Artificial Intelligence ; Brain* ; Diagnosis ; Diagnosis, Differential ; Discrimination (Psychology)* ; Epilepsy ; Epilepsy, Temporal Lobe* ; Humans ; Neural Networks (Computer) ; Nuclear Medicine ; Temporal Lobe*

PURPOSE: Transient wall motion abnormality and contractile dysfunction of the left ventricle (LV) can be observed in patients with coronary artery disease due to post-stress myocardial stunning. To understand clinical characteristics of stress induced LV dysfunction, we have compared the findings of exercise stress test, myocardial perfusion SPECT and coronary angiography between subjects with and without post-stress LV dysfunction. MATERIALS AND METHODS: Among subjects who underwent exercise stress test, myocardial perfusion SPECT and coronary angiography within a month of interval, we enrolled 36 patients with post-stress LV ejection fraction (LVEF) was > or=5% lower than rest (stunning group) and 16 patients with difference of post-stress and rest LVEF was lesser than 1% (non-stunning group) for this study. Treadmill exercise stress gated myocardial perfusion SPECT was performed with dual head SPECT camera using 740 MBq Tc-99m MIBI and coronary angiography was also performed by conventional Judkins method. RESULTS: Stunning group had a significantly higher incidence of hypercholesterolemia than non-stunning group (45.5 vs. 7.1%, p=0.01). Stunning group also had higher incidence of diabetes mellitus and lower incidence of hypertension, but these were not statistically significant. Stunning group had larger and more severe perfusion defect in stress perfusion myocardial SPECT than non-stunning group (extent 18.2 vs. 9.2%, p=0.029; severity 13.5 vs. 6.9, p=0.040). Stunning group also had higher degree of reversibility of perfusion defect, higher incidence of positive exercise stress test and higher incidence of having severe stenosis (80~99%) in coronary angiography than non-stunning group, but these were not statistically significant. In stunning group, all of 4 patients without perfusion defect had significant coronary artery stenosis and had received revascularization treatment. CONCLUSION: Patients with post-stress LV dysfunction had larger and more severe perfusion defect and severe coronary artery stenosis than patients without post-stress LV dysfunction. All of the patients without perfusion defect in stunning group had significant coronary artery stenosis and needed revascularization. Therefore, we suggest that invasive diagnostic procedures and therapeutic interventions might be needed in patients with post-stress LV dysfunction.
Angiography ; Constriction, Pathologic ; Coronary Angiography* ; Coronary Artery Disease ; Coronary Stenosis ; Diabetes Mellitus ; Electrocardiography* ; Exercise Test ; Head ; Heart Ventricles ; Humans ; Hypercholesterolemia ; Hypertension ; Incidence ; Myocardial Stunning* ; Perfusion* ; Tomography, Emission-Computed, Single-Photon*

We compared rest perfusion PET with redistribution perfusion SPECT to investigate the concordant rate between PET and SPECT images and analyze the discordant pattern. MATERIALS AND METHODS: Rest N-13 ammonia and F-18 FDG PET were performed on 18 patients with old myocardial infarction and left ventricular dysfunction whose dipyridamole - 4hr redistribution Tl-201 SPECT showed one or more severe fixed defects. Regional perfusion and metabolism were evaluated visually and quantitatively with 5-segment myocardial model. RESULTS: There were high concordant rate in uptake pattern (80/90 segments, 88.9%) and high correlation coefficient on quantitative analysis (R=0.81, p< 0.001) between redistrubution Tl-201 SPECT and N-13 ammonia PET images. Nine of 18 patients had SPECT-PET concordant pattern (Group I). Ten segments (9 in inferior wall, 1 in apex) from the remaining 9 patients showed SPECT-PET discordant pattern with abnormal Tl-201 defect and near normal N-13 ammonia uptake (Group II). The diastolic and systolic left ventricular dimensions were significantly increased in Group II compared to those of Group I. When attenuation uncorrected N-13 ammonia PET images were reconstructed in Group II, it resulted in PET images with severe inferior wall defects nearly identical to those seen in redistribution Tl-201 SPECT images. CONCLUSION: Redistribution Tl-201 SPECT images showed high concordant rate and correlation with rest N-13 ammonia PET images. Most of discordant segments had fixed thallium defects in inferior wall with nearly normal N-13 ammonia uptake, which may result from severe left ventricular dilatation and attenuation by the left hemidiaphragm and cardiac blood pool.
Ammonia* ; Dilatation ; Dipyridamole ; Humans ; Metabolism ; Myocardial Infarction* ; Perfusion ; Thallium ; Tomography, Emission-Computed, Single-Photon* ; Ventricular Dysfunction, Left*