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Asia Oceania Journal of Nuclear Medicine & Biology - Volume:4 Issue: 2, Spring 2016

Asia Oceania Journal of Nuclear Medicine & Biology
Volume:4 Issue: 2, Spring 2016

  • تاریخ انتشار: 1395/04/04
  • تعداد عناوین: 9
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  • Teik Hin Tan, Chin Yeen Boey, Boon Nang Lee Pages 59-65
    Objective(s)
    The present study aimed to evaluate the role of pretherapeutic 18fluorine-fluorodeoxyglucose positron emission tomographycomputed tomography (18F-FDG PET-CT) and maximum standardized uptake value (SUVmax) in guiding the treatment strategy and predicting the prognosis of esophageal carcinoma, using the survival data of the patients.
    Methods
    The present retrospective, cohort study was performed on 40 consecutive patients with esophageal carcinoma (confirmed by endoscopic biopsy), who underwent pre-operative 18F-FDG PET-CTstaging between January 2009 and June 2014. All the patients underwent contrast-enhanced CT and non-contrasted 18F-FDG PET-CT evaluations.
    The patients were followed-up over 12 months to assess the changes in therapeutic strategies. Survival analysis was done considering the primary tumor SUVmax, using the Kaplan–Meier product-limit method.
    Results
    In a total of 40 patients, 18F-FDG PET-CT scan led to changes in disease stage in 26n (65.0%) cases, with upstaging and downstaging reported in 10n (25.0%) and 16n (40.0%) patients, respectively. The management strategy changed from palliative to curative in 10 out of 24 patients and from curative to palliative in 7 out of 16 cases. Based on the 18F-FDG PET-CT scan alone, the median survival of patients in the palliative group was 4.0n (95 % CI 3.0-5.0) months, whereas the median survival in the curative group has not been reached, based on the 12-month followup.
    Selection of treatment strategy on the basis of 18F-FDG PET/CT alone was significantly associated with the survival outcomes at nine months (P=0.03) and marginally significant at 12 months (P=0.05). On the basis of SUVmax, the relation between survival and SUVmax was not statistically significant.
    Conclusion
    18F-FDG PET/CT scan had a significant impact on stage stratification and subsequently, selection of a stage-specific treatment approach and the overall survival outcome in patients with esophageal carcinoma. However, pre-treatment SUVmax failed to stablish its usefulness in the assessment of patient prognosis and survival outcome.
    Keywords: FDG, PET, CT, oesophageal carcinoma, prognosis
  • Yasuyuki Takahashi, Mizuki Mochiki, Keiko Koyama, Toshihiko Ino, Hiroyuki Yamaji, Atsuko Kawakami Pages 66-71
    Objective(s)
    Use of a positron emission tomography (PET)/single-photon emission computed tomography (SPECT) system facilitates the simultaneous acquisition of images with fluorine-18 fluorodeoxyglucose (18F-FDG) and technetium (99mTc)-tetrofosmin. However, 18F has a short half-life, and 511 keV Compton-scattered photons are detected in the 99mTc energy window. Therefore, in this study, we aimed to investigate the consequences of these facts.
    Methods
    The crosstalk correction for images in the 99mTc energy window involved the dual energy window (DEW) subtraction method. In phantom studies, changes in the count of uniform parts in a phantom (due to attenuation from decay), signal detectability in the hot-rod part of the phantom, and the defect contrast ratio in a cardiac phantom were examined.
    Results
    For 18F-FDG in the step-and-shoot mode, nearly a 9% difference was observed in the count of projection data between the start and end positions of acquisition in the uniform part of the phantom. Based on the findings, the detectability of 12 mm hot rods was relatively poor. In the continuous acquisition mode, the count difference was corrected, and detectability of thehot rods was improved. The crosstalk from 18F to the 99mTc energy window was approximately 13%. In the cardiac phantom, the defect contrast in 99mTc images from simultaneous dual-radionuclide acquisition was improved by approximately 9% after DEW correction; the contrast after correction was similar to acquisition with 99mTc alone.
    Conclusion
    Based on the findings, the continuous mode is useful for 18F-FDG acquisition, and DEW crosstalk correction is necessary for 99mTc-tetrofosmin imaging.
    Keywords: 18F, FDG, 99mTc, tetrofosmin, DEW method, PET, SPECT system
  • Akira Maebatake, Ayaka Imamura, Yui Kodera, Yasuo Yamashita, Kazuhiko Himuro, Shingo Baba, Kenta Miwa, Masayuki Sasaki Pages 72-80
    Objective(s)
    The aim of this study was to determine the optimal reconstruction parameters for iterative reconstruction in different devices and collimators for dopamine transporter (DaT) single-photon emission computed tomography (SPECT). The results were compared between filtered back projection (FBP) and different attenuation correction (AC) methods.
    Methods
    An anthropomorphic striatal phantom was filled with 123I solutions at different striatum-to-background radioactivity ratios. Data were acquired using two SPECT/CT devices, equipped with a low-to-medium-energy general-purpose collimator (cameras A-1 and B-1) and a low-energy high-resolution (LEHR) collimator (cameras A-2 and B-2).
    The SPECT images were once reconstructed by FBP using Chang’s AC and once by ordered subset expectation maximization (OSEM) using both CTAC and Chang’s AC; moreover, scatter correction was performed. OSEM on cameras A-1 and A-2 included resolution recovery (RR). The images were analyzed, using the specific binding ratio (SBR). Regions of interest for the background were placed on both frontal and occipital regions.
    Results
    The optimal number of iterations and subsets was 10i10s on camera A-1, 10i5s on camera A-2, and 7i6s on cameras B-1 and B-2. The optimal full width at half maximum of the Gaussian filter was 2.5 times the pixel size. In the comparison between FBP and OSEM, the quality was superior on OSEM-reconstructed images, although edge artifacts were observed in cameras A-1 and A-2. The SBR recovery of OSEM was higher than that of FBP on cameras A-1 and A-2, while no significant difference was detected on cameras B-1 and B-2. Good linearity of SBR was observed in all cameras. In the comparison between Chang’s AC and CTAC, a significant correlation was observed on all cameras. The difference in the background region influenced SBR differently in Chang’s AC and CTAC on cameras A-1 and B-1.
    Conclusion
    Iterative reconstruction improved image quality on all cameras, although edge artifacts were observed in images captured by cameras with RR. The SBR of OSEM with RR was higher than that of FBP, while the SBR of OSEM without RR was equal to that of FBP. Also, the SBR of Chang’s AC varied with different background regions in cameras A-1 and B-1.
    Keywords: SPECT, CT, iterative reconstruction, attenuation correction
  • Nobuhiro Yada, Hideo Onishi Pages 81-89
    Objective
    In this study, we aimed to validate the accuracy of computed tomography-based attenuation correction (CTAC) using the bilinear scaling method.
    Methods
    The measured attenuation coefficient (μm) was compared to a theoretical attenuation coefficient (μt ) using four different CT scanners and an RMI 467 phantom. The effective energy of the CT beam X-rays was calculated, using the aluminum half-value layer method, and was used in conjunction with an attenuation map to convert the CT numbers to μm values for the photon energy of 140 keV. We measured the CT number of the RMI 467 phantom for each of four scanners, and compared the μm and μt values for the effective energies of the CT beam X-rays, effective atomic numbers, and physical densities.
    Results
    The μm values for CT beam X-rays with low effective energies decreased in high construction elements, compared with CT beam X-rays of high effective energies . As the physical density increased, the μm values elevated linearly. Compared with other scanners, the μm values obtained from the scanner with CT beam X-rays of the maximal effective energy increased once the effective atomic number exceeded 10.00. The μm value of soft tissue was equivalent to the μt value. However, the ratios of the maximal differences between the μm value and the μt value were 25.4% (lung) and 21.5% (bone) respectively. Additionally, the maximal differences in the μm values were 6.0% in the bone tissue for each scanner.
    Conclusion
    The bilinear scaling method could accurately convert CT numbers to μ values within the soft tissues.
    Keywords: Bilinear scaling, CTAC, attenuation coefficient, effective atomic number
  • Viktor Popov, Radovan Gospavic, Peter Knoll, Siroos Mirzaei Pages 90-97
    Objective(s)
    The objectives of this work was to assess the benefits of the application of Physiologically Based Pharmacokinetic (PBPK) models in patients with different neuroendocrine tumours (NET) who were treated with Lu-177 DOTATATE. The model utilises clinical data on biodistribution of radiolabeled peptides (RLPs) obtained by whole body scintigraphy (WBS) of the patients.
    Methods
    The blood flow restricted (perfusion rate limited) type of the PBPK model for biodistribution of radiolabeled peptides (RLPs) in individual human organs is based on the multi-compartment approach, which takes into account the main physiological processes in the organism: absorption, distribution, metabolism and excretion (ADME). The approach calibrates the PBPK model for each patient in order to increase the accuracy of the dose estimation. Datasets obtained using WBS in four patients have been used to obtain the unknown model parameters. The scintigraphic data were acquired using a double head gamma camera in patients with different neuroendocrine tumours who were treated with Lu-177 DOTATATE. The activity administered to each patient was 7400MBq.
    Results
    Satisfactory agreement of the model predictions with the data obtained from the WBS for each patient has been achieved.
    Conclusion
    The study indicates that the PBPK model can be used for more accurate calculation of biodistribution and absorbed doses in patients. This approach is the first attempt of utilizing scintigraphic data in PBPK models, which was obtained during Lu-177 peptide therapy of patients with NET.
    Keywords: PBPK model, radiolabeled peptides, whole body scintigraphy, Lu177, DOTATATE
  • Ashraf Fakhari, Amir Jalilian, Fariba Johari, Daha, Mehdi Shafiee, Ardestani, Ali Khalaj Pages 98-105
    Objective(s)
    In line with previous research on the development of conjugated bisphosphonate ligands as new bone-avid agents, in this study, DOTA conjugated alendronate (DOTA-ALN) was synthesized and evaluated after labeling with gallium-68 (68Ga).
    Methods
    DOTA-ALN was synthesized and characterized, followed by 68Ga-DOTA-ALN preparation, using DOTA-ALN and 68GaCl3 (pH: 4-5) at 92-95°C for 10 min. Stability tests, hydroxyapatite assay, partition coefficient calculation,
    biodistribution studies, and imaging were performed on the developed agent in normal rats.
    Results
    The complex was prepared with high radiochemical purity (>99% as depicted by radio thin-layer chromatography; specific activity: 310-320GBq/mmol) after solid phase purification and was stabilized for up to 90 min with a logP value of -2.91. Maximum ligand binding (65%) was observed in the presence of 50 mg of hydroxyapatite; a major portion of the activity was excreted through the kidneys. With the exception of excretory organs, gastrointestinal tract organs, including the liver, intestine, and colon, showed significant uptake; however, the bone uptake was low (
    Conclusion
    The high solubility and anionic properties of the complex led to major renal excretion and low hydroxyapatite uptake; therefore, the complex failed to demonstrate bone imaging behaviors.
    Keywords: Ga, 68, DOTA, Alendronate, Biodistribution, radiolabeling
  • Domenico Albano, Giovanni Bosio, Mattia Bertoli, Giulia Petrilli, Francesco Bertagna Page 106
    Hepatosplenic candidiasis is a fungal infection, which mostly affects patients with hematologic malignancies such as leukemia. The pathogenesis of this infection is not clear yet, and the liver is the most commonly affected organ. Diagnosis of hepatosplenic candidiasis can be only established via biopsy, since computed tomography (CT) scan, ultrasonography, and magnetic resonance imaging (MRI) yield non-specific results. The role of fluorine-18 fluorodeoxyglucose positron emission tomography /computed tomography (18F-FDG PET/CT) in diagnosis of hepatosplenic candidiasis remains undetermined, considering a few evidences in the literature. In this case report, we present the case of a 47-year-old patient, affected by acute myeloid leukemia, which was treated with three cycles of chemotherapy, resulting in the development of neutropenia and fever following the last cycle. The 18F-FDG PET/CT scan showed some foci of intense FDG uptake in the liver and spleen. The subsequent diagnostic investigations (i.e., abdominal CT scan and biopsy) were suggestive of hepatosplenic candidiasis. The patient was started on antifungal treatment with fluconazole. After one month, the clinical conditions were resolved, and the subsequent abdominal CT scan was negative.
    Keywords: 18F, FDG, PET, CT, hepatosplenic candidiasis, chronic disseminated candidiasis
  • Olusegun Akinwale Ayeni, Nico Malan, Emmanuel Niiboye Hammond, Mboyo, Di, Tamba Heben Vangu Pages 109-112
    Dextrocardia is a cardiac positional anomaly in which the heart is located in the right hemithorax with its base-to-apex axis directed to the right and caudad. Situs inversus is an autosomal recessive disorder that causes organs in the chest and abdomen to be positioned in a mirror image from their normal position. Dextrocardia may occur in isolation or as part of situs inversus. Similarly, situs inversus may occur with or without dextrocardia. Situs inversus accompanied with dextrocardia (situs inversus totalis) is a rare congenital abnormality occurring in 0.01% of live births. Herein, we present the case of a 35-yearold man with previously diagnosed situs inversus totalis with mirror-image dextrocardia, referred to our facility for diagnosis of coronary artery disease (CAD). The incidence and presentation of CAD in patients with dextrocardia are similar to the normal population. However, considerable attention should be paid to the acquisition of myocardial perfusion scintigraphy and data processing/analysis in this group of patients. The present case highlights the distinctive applications and potential pitfalls of myocardial perfusion single photon emission computed tomography (SPECT) imaging in patients with dextrocardia.
    Keywords: Dextrocardia, situs inversus totalis, myocardial perfusion imaging, Image processing
  • Patricia A. Bautista, Teofilo O.L. San Luis, Jr Pages 113-118
    While the introduction of radioactive tracers in the study of metabolic pathways has been well-documented in clinical thyroidology as early as 1924, the widespread utilization in other clinical specialties has been hampered by slow developments in radiation-detecting devices and in the production of appropriate radiopharmaceuticals, in addition to the morbid fear of radiation. In the Philippines, the first radioisotope laboratory was established in 1956. Ten years later, the Philippine Society of Nuclear Medicine was formed. Through the years, challenges were overcome, foundations were laid down,growth was encouraged, friendships with other organizations were built, adjustments were made, and rules were enforced. To date, there are approximately 58 nuclear medicine centers randomly distributed from north to south of the Philippines, 7 accredited nuclear medicine training institutions, 95 board-certified nuclear medicine physicians (a few of whom are also internationally recognized), and a regionally-indexed Philippine Journal of Nuclear Medicine. Qualifying examinations for technologists were also recently instated. International relations are constantly strengthened by sending trainees abroad and accepting foreign trainees here, as well as participating in conferences and other endeavors. While the cost of putting up nuclear medicine centers in the Philippines is still prohibitive, it should not pose too much of a constraint as there are foreign and local parties willing to help. With appropriate instrumentation, targeting radiopharmaceuticals and trained human resources, nuclear medicine can indeed contribute much to health care delivery.
    Keywords: nuclear medicine, Philippines, history