Radiolucent Pure Matrix Stones on Computed Tomography Scan, Arising in Patient with Type I Diabetes and Chronic Kidney Disease: A Case Report / 가정의학회지

Kidney matrix stones are a rare form of calculi, which are challenging to diagnose. Matrix stones consist of a proteinaceous material which has a radiolucent appearance that might be overlooked on imaging. Recently, endourological intervention has been the standard treatment method for matrix stones. We report a case of urinary matrix stones in a patient with type 1 diabetes mellitus and chronic kidney disease, in whom the stones formed into a pure matrix and were not visualized in the computed tomography scan. The stones were found after additional work-up, and they were managed using a transureteral stone basket, not through endourological intervention.

A Brief History of Nuclear Medicine Physics, Instrumentation, and Data Sciences in Korea / 대한핵의학회잡지

We review the history of nuclear medicine physics, instrumentation, and data sciences in Korea to commemorate the 60 th anniversary of the Korean Society of Nuclear Medicine. In the 1970s and 1980s, the development of SPECT, nuclear stethoscope, and bone densitometry systems, as well as kidney and cardiac image analysis technology, marked the beginning of nuclear medicine physics and engineering in Korea. With the introduction of PET and cyclotron in Korea in 1994, nuclear medicine imaging research was further activated. With the support of large-scale government projects, the development of gamma camera, SPECT, and PET systems was carried out. Exploiting the use of PET scanners in conjunction with cyclotrons, extensive studies on myocardial blood flow quantification and brain image analysis were also actively pursued. In 2005, Korea’s first domestic cyclotron succeeded in producing radioactive isotopes, and the cyclotron was provided to six universities and university hospitals, thereby facilitating the nationwide supply of PET radiopharmaceuticals. Since the late 2000s, research on PET/MRI has been actively conducted, and the advanced research results of Korean scientists in the fields of silicon photomultiplier PET and simultaneous PET/MRI have attracted significant attention from the academic community.Currently, Korean researchers are actively involved in endeavors to solve a variety of complex problems in nuclear medicine using artificial intelligence and deep learning technologies.

Clinical Usefulness of ¹⁸F-FC119S Positron-Emission Tomography as an Auxiliary Diagnostic Method for Dementia: An Open-Label, Single-Dose, Evaluator-Blind Clinical Trial

Recent Survey of Effective Doses of F-18 FDG Torso PET/CT in Korea and the Current Recommendations for CT Protocols of PET/CT / 대한핵의학회잡지

Purpose@#This study aimed to construct a database of the effective doses (ED) from F-18 fluorodeoxyglucose (FDG) torso positron emission tomography/computed tomography (PET/CT) in Korea to provide data that supports the reduction of the CT dose of PET/CT and optimization of PET/CT protocols in Korea. @*Methods@#We investigated data of ED and CT parameters of FDG PET/CT. The data were analyzed by body weight groups. @*Results@#A total of 31 hospitals participated in the survey (99 adults). The mean total EDs (± SD) were 8.77 ± 2.76, 10.93 ± 3.14, and 12.57 ± 3.79 mSv for the 55-, 70-, and 85-kg groups, respectively. The FDG EDs were 4.80 ± 0.98, 6.05 ± 1.15, and 6.89 ± 1.52 mSv, and the CT EDs were 4.00 ± 2.12, 4.88 ± 2.51, and 5.68 ± 2.89 mSv, respectively. Of the enrolled hospitals, 54.5% used ultra-low-dose CT protocols, and their CT ED was significantly lower than low-dose CT group in all groups (2.9 ± 1.0, 3.2 ± 1.1, and 3.3 ± 1.0 mSv vs. 6.6 ± 1.6, 7.2 ± 2.1, and 7.9 ± 2.2 mSv, all p < 0.001, respectively). In the ultra-low-dose CT group, the CT ED with the iterative reconstruction was significantly lower than that of CT without iterative reconstruction in the 55-kg group (2.4 ± 0.9 vs. 3.3 ± 0.9, p = 0.04). @*Conclusions@#These results and current recommendations can be helpful for optimizing PET/CT diagnostic reference level (DRL) and reducing unnecessary PET/CT radiation exposure.

Nrf2-Heme oxygenase-1 modulates autophagy and inhibits apoptosis triggered by elevated glucose levels in renal tubule cells

BACKGROUND: Autophagy is a highly balanced process in which lysosomes remove aged and damaged organelles and cellular proteins. Autophagy is essential to maintain homeostasis in the kidneys. METHODS: Using human renal tubule cells HK-2, we assessed the impact of high glucose (HG) on autophagy. We also evaluated the capability of sulforaphane (SFN) to protect the HK-2 cells from HG-induced apoptosis by modulating autophagy. RESULTS: SFN modulated autophagy and decreased apoptosis in the HK-2 cells that were cultured in 250 mM glucose medium for two days. The reactive oxygen species (ROS) levels increased, as expected, in the cells cultured in the 250 mM glucose medium. However, the SFN decreased the ROS levels in the HK-2 cells. The overexpression of heme oxygenase-1 (HO-1) by SFN decreased the expression of LC3 and beclin-1. LC3 and beclin-1 were involved in the downregulation of caspase-3 that was observed in the HG-induced cells. CONCLUSION: The activation of nuclear factor E2-related factor 2 (Nrf2)–HO–1 inhibited ROS expression and subsequently attenuated autophagy and cell apoptosis after HG injury was decreased. HG injury led to the activation of autophagy and HO-1 in order to combat oxidative stress and protect against cell apoptosis. Therefore, HO-1 activation can prevent ROS development and oxidative stress during HG injury, which considerably decreases autophagy and apoptosis.

Impact of chronic kidney disease on mortality: A nationwide cohort study

BACKGROUND: Mortality is higher in patients with chronic kidney disease (CKD) than in the general population, but little information is available on CKD-related mortality that is representative of the Korean population. Our objective was to investigate mortality risk in Korean patients with CKD. METHODS: We identified patients with incident CKD who had not undergone dialysis or kidney transplantation between January 1, 2003 and December 31, 2007 in Korea using the database of the Korean National Health Insurance Service-National Sample Cohort, and stratified the population into the following three groups: group 1 (n = 1,473), controls; group 2 (n = 2,212), patients with diabetes or hypertension, but without CKD; and group 3 (n = 2,212), patients with CKD. We then monitored them for all-cause mortality until December 2013. RESULTS: A total of 1,473 patients were included in this analysis. During the follow-up period, 941 patients in group 3 died (134 deaths/1,000 person-years) compared with 550 deaths in the group 2 (34 deaths/1,000 person-years) and 459 deaths in group 1 (30 deaths/1,000 person-years). The rate ratio for mortality rate was 4.5, and the hazard ratio for mortality was 4.88 (95% confidence interval [CI], 4.36–5.47, P < 0.001) in patients in group 3 compared with age- and sex-matched controls (group 1). The rate ratio for mortality rate was 4.0, and the hazard ratio for mortality was 4.36 (95% CI, 3.92–4.85, P < 0.001) in patients in group 3 compared with patients in group 2. CONCLUSION: In this nationally representative sample cohort, excess mortality was observed in Korean patients with incident CKD.

Having a Physician Rather than a Place as a Usual Source of Care Would Be Better - from 2012 Korea Health Panel Data

A usual source of care (USC) in primary care improves health care quality and can result in improved health. However, current research about the type of USC (place only vs. physician with a place) is insufficient as an evidence to support the value of primary care. We analyzed data from the 2012 Korea Health Panel survey of adults aged 18 years or older (n = 11,873) who reported whether having a USC or not to compare the effects by type of USC on medical care use and out-of-pocket costs. Descriptive analysis showed significant differences in the distributions of sociodemographic and health status factors except frequency of outpatient visit by type of USC. Adjusted odds ratios (ORs) of having a physician with a place compared to not having a USC were 4.05 for age 65 ≥ years (vs. < 35 years), 1.33 for females (vs. males), 0.63 for the fifth (highest) quintile (vs. the first) of household income, 1.62 for medical aid (vs. employee) health insurance, and 4.46 for having a chronic disease (vs. not). For those having a physician with a place (vs. only a place) as a USC, adjusted ORs of hospital admission and emergency room (ER) visit were 0.77 and 0.71 with out-of-pocket costs not significantly high. Those having a physician with a place (vs. only a place) as a USC included more patients with chronic diseases, but they had fewer hospital admissions and ER visits. When designing a plan for health care reform in Korea, promoting having a physician rather than a place as a USC would be a better policy.

Erythropoiesis-stimulating Agents and Anemia in Patients with Non-dialytic Chronic Kidney Disease

Anemia is common in patients with advanced chronic kidney disease (CKD). Though erythropoiesis-stimulating agents (ESAs) have been strongly endorsed in guidelines, it is of particular financial interest. Recently, the reimbursement of ESAs in non-dialytic patients was started by the Korean National Health Insurance System. Thus, we investigated the impact of the reimbursement of ESAs on the anemia care in non-dialytic CKD patients. Medical records of patients with advanced CKD (estimated GFR <30 mL/min/1.73 m2) were reviewed. Use of ESAs, blood transfusion, and hemoglobin concentrations were analyzed from one year prior to reimbursement to three years following. We used multivariable modified Poisson regression to estimate the utilization prevalence ratio (PRs). A total of 1,791 medical records were analyzed. The proportion of patients receiving ESAs increased from 14.8% before reimbursement to a peak 33.6% in 1 yr after reimbursement; thereafter, ESA use decreased to 22.4% in 3 yr after reimbursement (compared with baseline; PR, 2.19 [95% CI, 1.40-3.42]). In patients with Hb <10 g/dL, the proportion of receiving ESAs increased from 32.1% before reimbursement to 66.7% in 3 yr after reimbursement (compared with baseline; PR, 2.04 [95% CI, 1.25-3.32]). Mean hemoglobin concentrations were 10.06±1.54 g/dL before reimbursement and increased to 10.78±1.51 g/dL in 3 yr after the reimbursement change (P=0.001). However, the requirement of blood transfusion was not changed over time. With the reimbursement of ESAs, the advanced CKD patients were more likely to be treated with ESAs, and the hemoglobin concentrations increased.

A Case of Isolated Glycosuria Mediated by an SLC5A2 Gene Mutation and Characterized by Postprandial Heavy Glycosuria Without Salt Wasting

Familial renal glycosuria (FRG) is an inherited disorder characterized by persistent glycosuria in the absence of hyperglycemia. It is caused by mutations in the sodium-glucose co-transporter, leading to increase in the renal excretion of glucose and sodium. However, there have been no studies on the role of fasting and postprandial changes in the urinary sodium excretion in patients with FRG. We report a case of renal glycosuria, which was confirmed by a SLC5A2 mutation via gene sequencing, and compared the postprandial urinary glucose and sodium excretion. A 26-year-old man sometimes experienced glycosuria on routine screening; however, other laboratory findings were normal. His fasting and postprandial urinary glucose excretion levels were 295mg/dL and 2,170mg/dL, respectively. The fasting and postprandial urinary sodium excretion levels were 200mEq/L and 89mEq/L, respectively. In patients with FRG, excessive diuresis might be prevented by a compensatory mechanism that reduces postprandial sodium excretion.

Myeloid deletion of SIRT1 suppresses collagen-induced arthritis in mice by modulating dendritic cell maturation

The type III histone deacetylase silent information regulator 1 (SIRT1) is an enzyme that is critical for the modulation of immune and inflammatory responses. However, the data on its role in rheumatoid arthritis (RA) are limited and controversial. To better understand how SIRT1 regulates adaptive immune responses in RA, we evaluated collagen-induced arthritis (CIA) in myeloid cell-specific SIRT1 knockout (mSIRT1 KO) and wild-type (WT) mice. Arthritis severity was gauged on the basis of clinical, radiographic and pathologic scores. Compared with their WT counterparts, the mSIRT1 KO mice exhibited less severe arthritis, which was less destructive to the joints. The expression levels of inflammatory cytokines, matrix metalloproteinases and ROR-γT were also reduced in the mSIRT1 KO mice compared with the WT mice and were paralleled by reductions in the numbers of Th1 and Th17 cells and CD80- or CD86-positive dendritic cells (DCs). In addition, impaired DC maturation and decreases in the Th1/Th17 immune response were observed in the mSIRT1 KO mice. T-cell proliferation was also investigated in co-cultures with antigen-pulsed DCs. In the co-cultures, the DCs from the mSIRT1 KO mice showed decreases in T-cell proliferation and the Th1/Th17 immune response. In this study, myeloid cell-specific deletion of SIRT1 appeared to suppress CIA by modulating DC maturation. Thus, a careful investigation of DC-specific SIRT1 downregulation is needed to gauge the therapeutic utility of agents targeting SIRT1 in RA.

Effect of Harderian adenectomy on the statistical analyses of mouse brain imaging using positron emission tomography

Positron emission tomography (PET) using 2-deoxy-2-[18F] fluoro-D-glucose (FDG) as a radioactive tracer is a useful technique for in vivo brain imaging. However, the anatomical and physiological features of the Harderian gland limit the use of FDG-PET imaging in the mouse brain. The gland shows strong FDG uptake, which in turn results in distorted PET images of the frontal brain region. The purpose of this study was to determine if a simple surgical procedure to remove the Harderian gland prior to PET imaging of mouse brains could reduce or eliminate FDG uptake. Measurement of FDG uptake in unilaterally adenectomized mice showed that the radioactive signal emitted from the intact Harderian gland distorts frontal brain region images. Spatial parametric measurement analysis demonstrated that the presence of the Harderian gland could prevent accurate assessment of brain PET imaging. Bilateral Harderian adenectomy efficiently eliminated unwanted radioactive signal spillover into the frontal brain region beginning on postoperative Day 10. Harderian adenectomy did not cause any post-operative complications during the experimental period. These findings demonstrate the benefits of performing a Harderian adenectomy prior to PET imaging of mouse brains.

Estimation of Internal Motion for Quantitative Improvement of Lung Tumor in Small Animal / 의학물리

The purpose of this study was to estimate internal motion using molecular sieve for quantitative improvement of lung tumor and to localize lung tumor in the small animal PET image by evaluated data. Internal motion has been demonstrated in small animal lung region by molecular sieve contained radioactive substance. Molecular sieve for internal lung motion target was contained approximately 37 kBq Cu-64. The small animal PET images were obtained from Siemens Inveon scanner using external trigger system (BioVet). SD-Rat PET images were obtained at 60 min post injection of FDG 37 MBq/0.2 mL via tail vein for 20 min. Each line of response in the list-mode data was converted to sinogram gated frames (2~16 bin) by trigger signal obtained from BioVet. The sinogram data was reconstructed using OSEM 2D with 4 iterations. PET images were evaluated with count, SNR, FWHM from ROI drawn in the target region for quantitative tumor analysis. The size of molecular sieve motion target was 1.59x2.50 mm. The reference motion target FWHM of vertical and horizontal was 2.91 mm and 1.43 mm, respectively. The vertical FWHM of static, 4 bin and 8 bin was 3.90 mm, 3.74 mm, and 3.16 mm, respectively. The horizontal FWHM of static, 4 bin and 8 bin was 2.21 mm, 2.06 mm, and 1.60 mm, respectively. Count of static, 4 bin, 8 bin, 12 bin and 16 bin was 4.10, 4.83, 5.59, 5.38, and 5.31, respectively. The SNR of static, 4 bin, 8 bin, 12 bin and 16 bin was 4.18, 4.05, 4.22, 3.89, and 3.58, respectively. The FWHM were improved in accordance with gate number increase. The count and SNR were not proportionately improve with gate number, but shown the highest value in specific bin number. We measured the optimal gate number what minimize the SNR loss and gain improved count when imaging lung tumor in small animal. The internal motion estimation provide localized tumor image and will be a useful method for organ motion prediction modeling without external motion monitoring system.

Quantitative Assessment Technology of Small Animal Myocardial Infarction PET Image Using Gaussian Mixture Model / 의학물리

Nuclear medicine images (SPECT, PET) were widely used tool for assessment of myocardial viability and perfusion. However it had difficult to define accurate myocardial infarct region. The purpose of this study was to investigate methodological approach for automatic measurement of rat myocardial infarct size using polar map with adaptive threshold. Rat myocardial infarction model was induced by ligation of the left circumflex artery. PET images were obtained after intravenous injection of 37 MBq 18F-FDG. After 60 min uptake, each animal was scanned for 20 min with ECG gating. PET data were reconstructed using ordered subset expectation maximization (OSEM) 2D. To automatically make the myocardial contour and generate polar map, we used QGS software (Cedars-Sinai Medical Center). The reference infarct size was defined by infarction area percentage of the total left myocardium using TTC staining. We used three threshold methods (predefined threshold, Otsu and Multi Gaussian mixture model; MGMM). Predefined threshold method was commonly used in other studies. We applied threshold value form 10% to 90% in step of 10%. Otsu algorithm calculated threshold with the maximum between class variance. MGMM method estimated the distribution of image intensity using multiple Gaussian mixture models (MGMM2, em leader MGMM5) and calculated adaptive threshold. The infarct size in polar map was calculated as the percentage of lower threshold area in polar map from the total polar map area. The measured infarct size using different threshold methods was evaluated by comparison with reference infarct size. The mean difference between with polar map defect size by predefined thresholds (20%, 30%, and 40%) and reference infarct size were 7.04+/-3.44%, 3.87+/-2.09% and 2.15+/-2.07%, respectively. Otsu verse reference infarct size was 3.56+/-4.16%. MGMM methods verse reference infarct size was 2.29+/-1.94%. The predefined threshold (30%) showed the smallest mean difference with reference infarct size. However, MGMM was more accurate than predefined threshold in under 10% reference infarct size case (MGMM: 0.006%, predefined threshold: 0.59%). In this study, we was to evaluate myocardial infarct size in polar map using multiple Gaussian mixture model. MGMM method was provide adaptive threshold in each subject and will be a useful for automatic measurement of infarct size.

Performance Measurement of Siemens Inveon PET Scanner for Small Animal Imaging / 의학물리

Inveon PET is a recently developed preclinical PET system for small animal. This study was conducted to measure the performance of Inveon PET as recommended by the NEMA NU 4-2008. We measured the spatial resolution, the sensitivity, the scatter fraction and the NECR using a F-18 source. A 3.432 ns coincidence window was used. A 1 mm3 sized F-18 point source was used for the measurement of spatial resolution within an energy window of 350~625 keV. PET acquisition was performed to obtain the spatial resolution from the center to the 5 cm offset toward the edge of the transverse FOV. Sensitivity, scatter fraction, and NECR were measured within an energy window of 350~750 keV. For measuring the sensitivity, a F-18 line source (length: 12.7 cm) was used with concentric 5 aluminum tubes. For the acquisition of the scatter fraction and the NECR, two NEMA scatter phantoms (rat: 50 mm in diameter, 150 mm in length; mouse: 25 mm in diameter, 70 mm in length) were used and the data for 14 half-lives (25.6 hr) was obtained using the F-18 line source (rat: 316 MBq, mouse: 206 MBq). The spatial resolution of the F-18 point source was 1.53, 1.50 and 2.33 mm in the radial, tangential and axial directions, respectively. The volumetric resolution was 5.43 mm3 in the center. The absolute sensitivity was 6.61%. The peak NECR was 486 kcps @121 MBq (rat phantom), and 1056 kcps @128 MBq (mouse phantom). The values of the scatter fraction were 20.59% and 7.93% in the rat and mouse phantoms, respectively. The performances of the Inveon animal PET scanner were measured in this study. This scanner will be useful for animal imaging.

mage-Based Assessment and Clinical Significance of Absorbed Radiation Dose to Tumor in Repeated High-Dose (131)I Anti-CD20 Monoclonal Antibody (Rituximab) Radioimmunotherapy for Non-Hodgkin's Lymphoma / 핵의학분자영상

PURPOSE: We assessed the absorbed dose to the tumor (Dosetumor) by using pretreatment FDG-PET and whole-body (WB) planar images in repeated radioimmunotherapy (RIT) with 131I rituximab for NHL. MATERIALS AND METHODS: Patients with NHL (n=4) were administered a therapeutic dose of (131)I rituximab. Serial WB planar images after RIT were acquired and overlaid to the coronal maximum intensity projection (MIP) PET image before RIT. On registered MIP PET and WB planar images, 2D-ROIs were drawn on the region of tumor (n=7) and left medial thigh as background, and Dosetumor was calculated. The correlation between Dosetumor and the CT-based tumor volume change after RIT was analyzed. The differences of Dosetumor and the tumor volume change according to the number of RIT were also assessed. RESULTS: The values of absorbed dose were 397.7+/-646.2cGy (53.0~2853.0cGy). The values of CT-based tumor volume were 11.3+/-9.1 cc (2.9~34.2cc), and the % changes of tumor volume before and after RIT were -29.8+/-44.3% (-100.0%~+42.5%), respectively. Dosetumor and the tumor volume change did not show the linear relationship (p>0.05). Dosetumor and the tumor volume change did not correlate with the number of repeated administration (p>0.05). CONCLUSION: We could determine the position and contour of viable tumor by MIP PET image. And, registration of PET and gamma camera images was possible to estimate the quantitative values of absorbed dose to tumor.

The Evaluation of Scattering Effects for Various Source Locations within a Phantom in Gamma Camera / 의학물리

(131)I is a radiological isotope being used widely for treatment of cancer as emitting gamma-ray and it is also applied to estimate the function of thyroid for its accumulation in thyroid. However, (131)I is more difficult to quantitate comapred to (99m)Tc, because (131)I has multiple energy gamma-ray emissions compared to (99m)Tc which is a mono energetic gamma-ray source. Especially, scattered ray and septal penetration resulted by high energy gamma ray have a bad influence upon nuclear medicine image. The purpose of this study was to estimate scatter components depending on the different source locations within a phantom using Monte Carlo simulation (GATE). The simulation results were validated by comparing with the results of real experiments. Dual-head gamma camera (ECAM, Chicago, Illinois Siemens) with high energy, general-purpose, and parallel hole collimators (hole radius: 0.17 cm, septal thickness: 0.2 cm, length: 5.08 cm) was used in this experiment. The NaI crystal is 44.5x59.1 cm in height and width and 0.95 cm in thickness. The diameter and height of PMMA phantom were 16 cm and 15 cm, respectively. The images were acquired at 5 different locations of (131)I point source within the phantom and the images of (99m)Tc were also acquired for comparison purpose with low energy source. The simulation results indicated that the scattering was influenced by the location of source within a phantom. The scattering effects showed the same tendency in both simulation and actual experiment, and the results showed that the simulation was very adequate for further studies. The results supported that the simulation techniques may be used to generalize the scattering effects as a function of a point source location within a phantom.

Quantitation of In-Vivo Physiological Function using Nuclear Medicine Imaging and Tracer Kinetic Analysis Methods / 핵의학분자영상

Nuclear medicine imaging has an unique advantage of absolute quantitation of radioactivity concentration in body. Tracer kinetic analysis has been known as an useful investigation methods in quantitative study of in-vivo physiological function. The use of nuclear medicine imaging and kinetic analysis together can provide more useful and powerful intuition in understanding biochemical and molecular phenomena in body. There have been many development and improvement in kinetic analysis methodologies, but the conventional basic concept of kinetic analysis is still essential and required for further advanced study using new radiopharmaceuticals and hybrid molecular imaging techniques. In this paper, the basic theory of kinetic analysis and imaging techniques for suppressing noise were summarized.

Medical Application of Radiation Internal Dosimetry / 핵의학분자영상

Medical internal radiation dosimetry (MIRD) is an important part of nuclear medicine research field using therapeutic radioisotope. There have been many researches using MIRD for the development of new therapeutic approaches including radiopharmaceutical, clinical protocol, and imaging techniques. Recently, radionuclide therapy has been re-focused as new solution of intractable diseases, through to the advances of previous achievements. In this article, the basic concepts of radiation and internal radiation dosimetry are summarized to help understanding MIRD and its application to clinical application.

Small Animal 18FFDG PET Imaging for Tumor Model Study / 핵의학분자영상

PET allows non-invasive, quantitative and repetitive imaging of biological function in living animals. Small animal PET imaging with [18F]FDG has been successfully applied to investigation of metabolism, receptor-ligand interactions, gene expression, adoptive cell therapy and somatic gene therapy. Experimental condition of animal handling impacts on the biodistribution of [18F]FDG in small animal study. The small animal PET and CT images were registered using the hardware fiducial markers and small animal contour point. Tumor imaging in small animal with small animal [18F]FDG PET should be considered fasting, warming, and isoflurane anesthesia level. Registered imaging with small animal PET and CT image could be useful for the detection of tumor. Small animal experimental condition of animal handling and registration method will be of most importance for small lesion detection of metastases tumor model.

Facile Fabrication of Animal-Specific Positioning Molds For Multi-modality Molecular Imaging / 핵의학분자영상

PURPOSE: Recently multi-modal imaging system has become widely adopted in molecular imaging. We tried to fabricate animal-specific positioning molds for PET/MR fusion imaging using easily available molding clay and rapid foam. The animal-specific positioning molds provide immobilization and reproducible positioning of small animal. Herein, we have compared fiber-based molding clay with rapid foam in fabricating the molds of experimental animal. MATERIALS AND METHODS: The round bottomed-acrylic frame, which fitted into microPET gantry, was prepared at first. The experimental mice was anesthetized and placed on the mold for positioning. Rapid foam and fiber-based clay were used to fabricate the mold. In case of both rapid foam and the clay, the experimental animal needs to be pushed down smoothly into the mold for positioning. However, after the mouse was removed, the fabricated clay needed to be dried completely at 60 degrees C in oven overnight for hardening. Four sealed pipet tips containing [18F]FDG solution were used as fiduciary markers. After injection of [18F]FDG via tail vein, microPET scanning was performed. Successively, MRI scanning was followed in the same animal. RESULTS: Animal-specific positioning molds were fabricated using rapid foam and fiber-based molding clay for multimodality imaging. Functional and anatomical images were obtained with microPET and MRI, respectively. The fused PET/MR images were obtained using freely available AMIDE program. CONCLUSION: Animal-specific molds were successfully prepared using easily available rapid foam, molding clay and disposable pipet tips. Thanks to animal-specific molds, fusion images of PET and MR were co-registered with negligible misalignment.