• Nuclear Medicine and Molecular Imaging
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• v.41 no.2
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• pp.172-180
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• 2007

Among the nuclear medicine imaging methods available today, $H_2^{15}O-PET$ is most widely used by cognitive neuroscientists to examine regional brain function via the measurement of regional cerebral blood flow (rCBF). The short half-life of the radioactively labeled probe, $^{15}O$, often allows repeated measures from the same subjects in many different task conditions. $H_2^{15}O-$ PET, however, has technical limitations relative to other methods of functional neuroimaging, e.g., fMRI, including relatively poor time and spatial resolutions, and, frequently, insufficient statistical power for analysis of individual subjects. However, recent technical developments, such as the 3-D acquisition method provide relatively good image quality with a smaller radioactive dosage, which in turn results in more PET scans from each individual, thus providing sufficient statistical power for the analysis of individual subject's data. Furthermore, the noise free scanner environment $H_2^{15}O$ PET, along with discrete acquisition of data for each task condition, are important advantages of PET over other functional imaging methods regarding studying state-dependent changes in brain activity. This review presents both the limitations and advantages of $^{15}O-PET$, and outlines the design of efficient PET protocols, using examples of recent PET studies both in the normal healthy population, and in the clinical population.

• Radiation Oncology Journal
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• v.22 no.4
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• pp.288-297
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• 2004

Puporse: The aims of this study were to evaluate the change of $[^18F]fluoromisonidazole$($[^18F]FMISO$) uptake in C3H mouse squamous cell carcinoma-VII (SCC-VII) treated with mild hyperthermia ($42^{circ}C$) and nicotinamide and to assess the biodistribution of the markers in normal tissues under similar conditions. Methods and Materials: $[^18F]FMISO$ was producedby our hospital. Female C3H mice with a C3H SCC-VII tumor grown on their extremities were used. Tumors were size matched. Non-anaesthetized, tumor-bearing mice underwent control or mild hyperthermia at $42^{circ}C$ for 60 min with nicotinamide (50 mg/kg i.p. injected) and were examined by gamma counter, autoradiography and animal PET scan 3 hours after tracer i.v. injected with breathing room air, The biodistribution of these agents were obtained at 3 h after $[^18F]FMISO$ injection. Blood, tumor, muscle, heart, lung, liver, kidney, brain, bone, spleen, and intestine were removed, counted for radioactivity and weighed. The tumor and liver were frozen and cut with a cryomicrotome into 10- um sections. The spatial distribution of radioactivity from the tissue sections was determined with digital autoradiography. Results: The mild hyperthermia with nicotinamide treatment had only slight effects on the biodistribution of either marker in normal tissues. We observed that the whole tumor radioactivity uptake ratios were higher in the control mice than in the mild hyperthermia with nicotinamide treated mice for $[^18F]FMISO$ ($1.56{\pm}1.03$ vs. $0.67{\pm}0.30$; p=0.063). In addition, autoradiography and animal PET scan demonstrated that the area and intensity of $[^18F]FMISO$ uptake was significantly decreased. Conclusion: Mild hyperthermla and nicotinamide significantly improved tumor hypoxia using $[^18F]FMISO$ and this uptake reflected tumor hypoxic status.

• The Korean Journal of Nuclear Medicine
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• v.34 no.4
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• pp.276-284
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• 2000

Purpose: We investigated the operative outcome after bypass surgery in patients selected using viability criteria on F-18 FDG PET. Materials and Methods: Rest-24hr delay redistribution imaging of Tl-201 SPECT and F-18 FDG PET were performed in 11 patients. Seven of these 11 patients (6 men, 1 woman) were evaluated to have viable myocardium by F-18 FDG PET. Changes in symptoms and left ventricular ejection fraction (LVEF) after operation were evaluated. Results: In seven of 11 patients, a significant amount of viable myocardium was found on F-18 FDG PET and Tl-201 SPECT. Severity of both chest pain and dyspnea improved markedly in all patients. Mean LVEF improved from 22% to 32%. Conclusion: F-18 FDG PET could be used to select the patients who will benefit from coronary artery bypass surgery.

• Nuclear Medicine and Molecular Imaging
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• v.42 no.4
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• pp.275-284
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• 2008

Purpose: We intended to evaluate myocardial oxygen consumption ($MVO_2)$ by applying recirculation correction and modified one-compartment model to have a reference range of $MVO_2$ in normal young population and to reveal the effect of recirculation on time-activity curve (TAC). Materials and Methods: In nine normal male volunteers with mean age of $26.3{\pm}4.0$, $MVO_2$ was estimated with 925 MBq (25mCi) of $^{11}C$-Acetate (Neuroscience Research Institute, Gachon University of Medicine and Science, Incheon, Korea) and PET/CT (Biograph 6, Siemens Medical Solution, Germany). Analysis software such as $MATLAB^{(R)}$ v7.1 (Mathworks, Inc., United States), $Excel^{(R)}$ 2007 (Microsoft, United States), and $SPSS^{(R)}$ v12.0 (Apache Software Foundation, United States) were used. Twenty three frames were of $12{\times}10$, $5{\times}60$, $3{\times}120$, $2{\times}300's$ duration, respectively. The modified one-compartmental model and the recirculation correction method were applied. Statistical analysis was performed by using Test of Normality, ANOVA and Post-Hoc (Scheffe's) analysis, and p-value less than 0.05 was considered as significant. Results: The normal reference ranges of $MVO_2$ were presented as $3.18-4.64\;{\times}\;10^{-4}\;ml/g/sec$, $1.91-3.94\;{\times}\;10^{-4}\;ml/g/sec$, $4.31-6.40\;{\times}\;10^{-4}\;ml/g/sec$, $2.84-4.53\;{\times}\;10^{-4}\;ml/g/sec$ and $3.42-5.00\;{\times}\;10^{-4}\;ml/g/sec$ in the septum, the inferior wall, the lateral wall, the anterior wall and the entire wall, respectively. In addition, it was noted that the dual exponentiality of the clearance curve is due to the recirculation effect and that the characteristic of the curve is essentially mono-exponential. Conclusion: $^{11}C$-Acetate is a radiotracer worthwhile to assess $MVO_2$. Re-circulated $^{11}C$ can influence TAC of $^{11}C$ in myocadia and so the recirculation correction must be considered when measuring $MVO_2$.

• Journal of the Korean Society of Radiology
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• v.16 no.2
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• pp.95-102
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• 2022

This study compares the difference between the remaining amount in syringes according to injection method and the dose of physiological saline when the radiopharmaceutical ¹⁸F-FDG isotope is injected into patients who visited the hospital for PET examination. After performing a CT or MRI using a contrast medium when ¹⁸F-FDG was injected into 40 patients who came to the hospital for PET examination without removing the 3-way, the radioactivity remaining in the syringe and the 3-way was measured and the dose of radioactivity confirmed. At this time, 20 patients were divided into different dose groups of physiological saline. Another injection method was used to compare the remaining amount of the syringe and the difference in the remaining amount according to the amount of physiological saline when the injection was performed with an extension. After an injection of ¹⁸F-FDG, the actual administered dose was confirmed by measuring the radioactivity remaining in the syringe and the 3-way or extension with a calibrator. As a result of measuring the radioactivity of the syringe before administering the radiopharmaceutical and the radioactivity of the syringe and the 3-way or extension after administration, the 3-way injection method in 10 cc's of physiological saline had the lowest residual amount. The remaining amount increased in the order of the extension to 10 cc's of saline and the 3-way to 5 cc's of saline. Likewise, the 5 cc's saline solution and the extension injection method demonstrated the highest residual amounts. The residual difference with the lowest level of remaining injection method was found to be 0.053 mCi. It was found that in a PET examination, by considering the radioactivity remaining in the 3-way and extension and by adjusting the dose of physiological saline, if the intended dose to be administered to the actual patient is determined, it is possible to administer the radiopharmaceutical to the patient more accurately.

• Journal of Digestive Cancer Research
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• v.1 no.1
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• pp.53-57
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• 2013

There is no established treatment for esophageal carcinoma with metastasis. For the metastatic esophageal squamous cell carcinoma, chemotherapy or best supportive care according to patient's performance status are accepted as an available treatment. We report a case of complete remission after concurrent chemoradiotherapy for esophageal squamous cell carcinoma with metastatic lesion in 5th thoracic vertebrae. A 57-year-old man with ongoing dysphagia and weight loss was admitted to our hospital. On the endoscopic and radiologic imaging evaluation,the patient was diagnosed as a squamous cell carcinoma of esophagus with solitary metastatic lesion in 5th thoracic vertebrae. The patient was treated with combination chemotherapy (5-fluorouracil (5-FU) and cisplatin) and concurrent radiotherapy for two months to relieve dysphagia. Because metastatic lesion in thoracic vertebrae was located near the primary esophageal tumor, the metastatic lesion could be included within the radiation field. After concurrent chemoradiotherapy, consecutive 4 cycles of chemotherapy had been carried out. Primary esophageal tumor with metastatic lymph nodes and metastatic lesion in 5th thoracic vertebrae disappeared on follow up computed tomography (CT) and positron emission tomography-CT (PET-CT). Follow up endoscopic biopsy revealed no remnant malignant cells at previous primary cancer lesion.

• Korean Journal of Clinical Laboratory Science
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• v.56 no.2
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• pp.147-155
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• 2024

Gallium-68-prostate-specific membrane antigen-11 (⁶⁸Ga-PSMA-11) is a positron emission tomography radiopharmaceutical that labels a Glu-urea-Lys-based ligand with ⁶⁸Ga, binding specifically to the PSMA. It is used widely for imaging recurrent prostate cancer and metastases. On the other hand, the preparation and quality control testing of ⁶⁸Ga-PSMA-11 in medical institutions takes over 60 minutes, limiting the daily capacity of ⁶⁸Ge/⁶⁸Ga generators. While the generator provides 1,110 MBq (30 mCi) nominally, its activity decreases over time, and the labeling yield declines irregularly. Consequently, additional preparations are needed, increasing radiation exposure for medical technicians, prolonging patient wait times, and necessitating production schedule adjustments. This study aimed to reduce the ⁶⁸Ga-PSMA-11 preparation time and optimize the automated synthesis system. By shortening the reaction time between ⁶⁸Ga and the PSMA-11 precursor and adjusting the number of purification steps, a faster and more cost-effective method was tested while maintaining quality. The final synthesis time was reduced from 30 to 20 minutes, meeting the standards for the HEPES content, residual solvent EtOH content, and radiochemical purity. This optimized procedure minimizes radiation exposure for medical technicians, reduces patient wait times, and maintains consistent production schedules, making it suitable for clinical application.

• Journal of the Korean Society of Radiology
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• v.81 no.6
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• pp.1424-1435
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• 2020

Purpose The purpose of this study was to evaluate the usefulness of multiphasic CT and ¹⁸F-fluorodeoxyglucose (FDG) PET/CT for the differentiation of combined hepatocellular carcinoma-cholangiocarcinoma (cHCC-CCA) from hepatocellular carcinoma (HCC). Materials and Methods From January 2007 to April 2016, 93 patients with pathologically confirmed HCC (n = 84) or cHCC-CCA (n = 9) underwent CT and PET/CT imaging. Contrast enhancement patterns were divided into three types based on the attenuation of the surrounding liver parenchyma: type I (early arterial enhancement with delayed washout), type II (early arterial enhancement without delayed washout), and type III (early hypovascular, infiltrative appearance, or peripheral rim enhancement). Results cHCC-CCAs (89%) had a higher PET/CT positive rate than did HCCs (61%), but the PET/CT positive rate did not differ significantly (p = 0.095). Among the 19 cases of the type II enhancement pattern, 3 (21%) of 14 HCCs and 4 (80%) of 5 cHCC-CCAs were PET/CT positive. cHCC-CCAs had a significantly higher PET/CT positive rate (p = 0.020) in the type II enhancement pattern. Conclusion The PET/CT positive rate of cHCC-CCA was significantly higher than that of HCC in lesions with a type II enhancement pattern. The ¹⁸F-FDG PET/CT can be useful for the differentiation of cHCC-CCA from HCC in lesions with a type II enhancement pattern on multiphasic CT.

• Annals of Hepato-Biliary-Pancreatic Surgery
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• v.27 no.4
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• pp.403-414
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• 2023

Backgrounds/Aims: Pancreatoduodenectomy (PD) is recommended in fit patients with a carcinoma (PDAC) of the pancreatic head, and a delayed resection may affect survival. This study aimed to correlate the time from staging to PD with long-term survival, and study the impact of preoperative investigations (if any) on the timing of surgery. Methods: Data were extracted from the Recurrence After Whipple's (RAW) study, a multicentre retrospective study of PD outcomes. Only PDAC patients who underwent an upfront resection were included. Patients who received neoadjuvant chemo-/radiotherapy were excluded. Group A (PD within 28 days of most recent preoperative computed tomography [CT]) was compared to group B (> 28 days). Results: A total of 595 patents were included. Compared to group A (median CT-PD time: 12.5 days, interquartile range: 6-21), group B (49 days, 39-64.5) had similar one-year survival (73% vs. 75%, p = 0.6), five-year survival (23% vs. 21%, p = 0.6) and median time-to-death (17 vs. 18 months, p = 0.8). Staging laparoscopy (43 vs. 29.5 days, p = 0.009) and preoperative biliary stenting (39 vs. 20 days, p < 0.001) were associated with a delay to PD, but magnetic resonance imaging (32 vs. 32 days, p = 0.5), positron emission tomography (40 vs. 31 days, p > 0.99) and endoscopic ultrasonography (28 vs. 32 days, p > 0.99) were not. Conclusions: Although a treatment delay may give rise to patient anxiety, our findings would suggest this does not correlate with worse survival. A delay may be necessary to obtain further information and minimize the number of PD patients diagnosed with early disease recurrence.

• Nuclear Medicine and Molecular Imaging
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• v.42 no.1
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• pp.29-38
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• 2008

Purpose: The aim of this study was to investigate the feasibility of 3 ' -[F-18]fluoro-3 ' -deoxythymidine positron emission tomography(FLT-PET) for the detection of locally advanced breast cancer and to compare the degree of FLT and 2' -deoxy-2 ' -[F-18]fluoro-d-glucose(FDG) uptake in primary tumor, lymph nodes and other normal organs. Material & Methods: The study subjects consisted of 22 female patients (mean age; $42{\pm}6$ years) with biopsy-confirmed infiltrating ductal carcinoma between Aug 2005 and Nov 2006. We performed conventional imaging workup, FDG-PET and FLT PET/CT. Average tumor size measured by MRI was $7.2{\pm}3.4$ cm. With visual analysis, Tumor and Lymph node uptakes of FLT and FDG were determined by calculation of standardized uptake value (SUV) and tumor to background (TB) ratio. We compared FLT tumor uptake with FDG tumor uptake. We also investigated the correlation between FLT tumor uptake and FDG tumor uptake and the concordant rate with lymph node uptakes of FLT and FDG. FLT and FDG uptakes of bone marrow and liver were measured to compare the biodistribution of each other. Results: All tumor lesions were visually detected in both FLT-PET and FDG-PET. There was no significant correlation between maximal tumor size by MRI and SUVmax of FLT-PET or FDG-PET (p>0.05). SUVmax and $$SUV_{75} (average SUV within volume of interest using 75% isocontour) of FLT-PET were significantly lower than those of FDG-PET in primary tumor (SUVmax; $6.3{\pm}5.2\;vs\;8.3{\pm}4.9$, p=0.02 /$SUV_{75};\;5.3{\pm}4.3\;vs\;6.9{\pm}4.2$, p=0.02). There is significant moderate correlation between uptake of FLT and FDG in primary tumor (SUVmax; rho=0.450, p=0.04 / SUV75; rho=0.472, p=0.03). But, TB ratio of FLT-PET was higher than that of FDG-PET($11.7{\pm}7.7\;vs\;6.3{\pm}3.8$, p=0.001). The concordant rate between FLT and FDG uptake of lymph node was reasonably good (33/34). The FLT SUVs of liver and bone marrow were $4.2{\pm}1.2\;and\;8.3{\pm}4.9$. The FDG SUVs of liver and bone marrow were $1.8{\pm}0.4\;and\;1.6{\pm}0.4$. Conclusion: The uptakes of FLT were lower than those of FDG, but all patients of this study revealed good FLT uptakes of tumor and lymph node. Because FLT-PET revealed high TB ratio and concordant rate with lymph node uptakes of FDG-PET, FLT-PET could be a useful diagnostic tool in locally advanced breast cancer. But, physiological uptake and individual variation of FLT in bone marrow and liver will limit the diagnosis of bone and liver metastases.