Pertechnetate Tc Research Articles

Предикторы эффективности терапии радиоактивным йодом болезни Грейвса у детей и подростков

RATIONALE : Insufficient world–wide clinical experience in radioiodine therapy (RIT) for Graves’ disease (GD) in children and adolescents, and limited knowledge of the predictors of RIT efficacy. AIMS : Analysis and identification of the most significant predictors of the efficacy of RIT in children and adolescents with Graves’ disease. MATERIALS AND METHODS : A total of 55 patients (48 females and 7 males) aged from 8 to 18 years receiving primary RIT for GD were enrolled. RIT planning was based on the dosimetric method. Analyzed parameters included gender, age, ultrasound thyroid volume before and 6 months after treatment, the presence of endocrine ophthalmopathy, duration of antithyroid drug (ATD) therapy, relapse of thyrotoxicosis after ATD dose reduction, blood fT3, fT4 and TSH levels initially and at 1, 3, 6 months after treatment, TSH receptor Ab initially and at 3 and 6 months after treatment, thyroid 99m Tc–pertechnetate uptake at 10–20 minutes (%), maximum thyroid 131 I uptake (%), specific 131 I uptake (MBq/g) and therapeutic 131 I activity (MBq). Fisher exact test, non–parametric Mann–Whitney test, Wilcoxon signed–rank test, logistic regression modelling, ROC–analysis, proportional hazard model (the Cox regression), the Kaplan–Meier method and log–rank test were used for statistical analysis as appropriate. RESULTS : Six months after RIT, hypothyroidism was achieved in 45 (81.8%), euthyroid state – in 2 (3.6%), and in 8 (14.6%) patients thyrotoxicosis persisted. On univariate statistical analysis, the smaller thyroid volume, higher fT4 and lower TSH receptor Ab levels, lower 99m Tc–pertechnetate uptake and higher specific 131 I uptake were associated with hypothyroidism. On multivariate logistic regression analysis, the older patient’s age (p=0.011), smaller thyroid volume (p=0.003) and higher fT4 (p=0.024) were independent predictors of RIT efficacy. Thyroid volume was also the only variable associated with achievement of hypothyroidism in time after RIT (p=0.011). CONCLUSION : The efficacy of dosimetry–based RIT in children and adolescents with GD 6 months after treatment was 81.2%. Older patients’ age, smaller thyroid volume and higher fT4 level were independent predictors of therapy success. Smaller thyroid volume was also a predictor of the favorable time–related outcome. Statistical models obtained in this work may be used to prospectively estimate the chance of efficient RIT for GD in pediatric patients.

Chromosome aberrations during in-vitro labeling of red blood cells with 99mTc: a study with cytokinesis block micronucleus assay in human peripheral blood lymphocytes.

Radiopharmaceuticals are special medicines composed by a radionuclide and a non-radioactive compound characterized by non-pharmacodynamic effects, low prevalence of side effects, and a possible risk of oncogenesis, since its administration to patients supposes a radiation dose to organism. Over these years, radiation damage induced by diagnosis radiopharmaceuticals has been evaluated, including the radiolabeled autologous cells, a group of radiopharmaceuticals where blood cells extracted from patients are labeled in-vitro and readministered for diagnosis. There is not a consensus about the possibility of increasement of risk for malignancies associated with the radiolabeled blood cells, so for a more accurate evaluation of the potential oncogenic risk related to the administration of [Tc]Tc labeled red blood cells, radiation dose received by the cells during the labeling process is studied by means of the cytokinesis-blocked micronucleus (CBMN) assay and a dose-response curve constructed by in-vitro external irradiation of blood samples. Our work enables to establish the range of activity to be added during the in-vitro labeling of red blood cells with [Tc]Tc pertechnetate to avoid radiation damage to cells. Activities recommended for blood volume determination and angiography do not increase the risk of malignancies, whilst activities of 370 MBq show chromosome aberrations in lymphocytes. Evaluation of the radiation damage related to the in-vitro labeling is recommended to estimate the potential oncogenic risk and minimize it.

Does Salivary Function Decrease in Proportion to Radioiodine Dose?

This study was conducted to investigate the dose-response characteristics of radioiodine on salivary glands and to investigate the mechanism responsible for radioiodine-induced salivary glands toxicity. Twenty-four mice were divided into six groups: 0, 0.05, 0.10, 0.20, 0.40, and 0.80 mCi/20 g mouse, administered orally. Mortalities were noted 12 months after radioiodine administration. Body weights, gland weights, salivary lag times, flow rates, and changes in 99m Tc pertechnetate were recorded. Histopathological changes and mRNA expressions were also evaluated, and immunohistochemical analysis and apoptotic assays were performed. Survival rates, body weights, gland weights, and flow rates decreased, and lag times increased on increasing radioiodine dose. Animals administered radioiodine showed acinar atrophy, striated duct dilations, and lymphocytic infiltration in glands and irregular destruction of epithelial surfaces of tongue. The uptake and excretion of 99m Tc pertechnetate were impaired by radioiodine. Immunohistochemical analysis showed that numbers of salivary epithelial, myoepithelial, and endothelial cells decreased and that numbers of ductal cells increased with radioiodine dose. Oxidative stress biomarker levels increased; reactive oxygen species scavenger levels decreased; and numbers of apoptotic cells increased in animals exposed to higher radioiodine doses. These dose-related, long-term effects on salivary gland should be taken into account when determining radioiodine doses. NA Laryngoscope, 130:2173-2178, 2020.

Assessment of normal reference values for thyroid uptake of technetium-99m pertechnetate in a single centre UK population.

This study aims to explore the normal reference values for thyroid uptake of technetium-99m (Tc) pertechnetate in a UK population. A retrospective review of 60 euthyroid patients who underwent thyroid imaging with Tc pertechnetate between January 2012 to April 2014 as part of dual-tracer subtraction parathyroid scintigraphy. Tc pertechnetate thyroid uptake values were determined for each patient. Medical records and biochemical thyroid function tests were reviewed to ensure that all patients were not on medication that could affect thyroid function and they were both clinically and biochemically euthyroid 6 months before and following the scan. Median and interquartile uptake range of Tc pertechnetate in euthyroid patients were 0.9 and 0.5-1.4%, respectively. The normal reference range in the study population was 0.2-2.0%. Thyroid uptake inversely correlated with age in females (r=-0.40, P=0.04), males (r=-0.50, P=0.04), and whole group (r=-0.40, P=0.002). The calculated normal reference range in this study was found to be less than that used in our own and many other UK institutions. The results demonstrate the importance of periodic evaluation of normal uptake values and provide support for prospective studies defining the normal reference range to be performed.

99mTc Pertechnetate Uptake and its Agreement with 131I Uptake by Thyroid Gland

<p><strong><em>Background:</em></strong> With the advancement of science, the scope of thyroid uptake in diagnosis and treatment of thyroid diseases has become limited. Uptake test with <sup>99m</sup>Tc<strong> </strong>pertechnetate along with a thyroid scan, which is done almost routinely, could be a better option when needed. This will not only exempt the patients from relatively higher radiation burden but also cause significant reduction of procedural time. Moreover, the thyroid image we get along with the uptake may guide with additional information. This study was done to provide preliminary data regarding thyroid uptake test with <sup>99m</sup>Tc<strong> </strong>in our population and to assess the possibilities of introducing this safer and convenient radionuclide in our routine practice.</p><p><strong><em>Patients and methods:</em></strong> This cross sectional, comparative study was conducted from January to December of 2015 on 59 participants in Institute of Nuclear Medicine and Allied Sciences, Dhaka. Patients coming for a radioactive iodine uptake test along with a thyroid scan were enrolled. Uptake of <sup>99m</sup>Tc pertechnetate at 20 minutes and at 24 hours was measured. Data were analyzed between the two uptake values based on clinical conditions, serum TSH levels and gland size.</p><p><strong><em>Results:</em></strong> Almost perfect agreement and a strong positive correlation (Kappa value=0.933 & r =0.845) were found between the results of two modalities. The hyperthyroid group showed a moderate agreement (k=0.5) and a moderate positive correlation (r=0.6). The participants with thyroiditis revealed a perfect agreement (k=1) and a strong positive correlation (r=0.981). Almost perfect correlation was found between participants with enlarged and non-enlarged glands (r=0.776 & 0.801 respectively). Agreement analysis revealed almost perfect agreement (k=0.88) in the group with enlarged and moderate agreement (k=0.6) in participants with non-enlarged glands. Low serum TSH group showed perfect agreement (k=1.0) and a strong positive correlation (r=0.748). The group with normal TSH level revealed a perfect agreement with k=1 but a moderate correlation (r=0.418).</p><p><strong><em>Conclusion:</em></strong> Good agreement and correlation were found between thyroid uptakes of <sup>99m</sup>Tc at 20 minutes by gamma camera and that of at 24 hours. Agreement and correlation in different clinical settings also showed consistency. So, <sup>99m</sup>Tc may be considered for uptake test in a regular basis in the limited fields where an uptake is still required as it may yield a reliable result in a simple, quicker and more convenient method.</p><p>Bangladesh J. Nuclear Med. 20(2): 105-109, July 2017</p>

Technical Note: Development of a 3D printed subresolution sandwich phantom for validation of brain SPECT analysis.

To make an adaptable, head shaped radionuclide phantom to simulate molecular imaging of the brain using clinical acquisition and reconstruction protocols. This will allow the characterization and correction of scanner characteristics, and improve the accuracy of clinical image analysis, including the application of databases of normal subjects. A fused deposition modeling 3D printer was used to create a head shaped phantom made up of transaxial slabs, derived from a simulated MRI dataset. The attenuation of the printed polylactide (PLA), measured by means of the Hounsfield unit on CT scanning, was set to match that of the brain by adjusting the proportion of plastic filament and air (fill ratio). Transmission measurements were made to verify the attenuation of the printed slabs. The radionuclide distribution within the phantom was created by adding (99m)Tc pertechnetate to the ink cartridge of a paper printer and printing images of gray and white matter anatomy, segmented from the same MRI data. The complete subresolution sandwich phantom was assembled from alternate 3D printed slabs and radioactive paper sheets, and then imaged on a dual headed gamma camera to simulate an HMPAO SPECT scan. Reconstructions of phantom scans successfully used automated ellipse fitting to apply attenuation correction. This removed the variability inherent in manual application of attenuation correction and registration inherent in existing cylindrical phantom designs. The resulting images were assessed visually and by count profiles and found to be similar to those from an existing elliptical PMMA phantom. The authors have demonstrated the ability to create physically realistic HMPAO SPECT simulations using a novel head-shaped 3D printed subresolution sandwich method phantom. The phantom can be used to validate all neurological SPECT imaging applications. A simple modification of the phantom design to use thinner slabs would make it suitable for use in PET.

Radioprotective Effect of Epigallocatechin-3-Gallate on Salivary Gland Dysfunction After Radioiodine Ablation in a Murine Model.

Objectives.Radioiodine (RI) therapy is known to subject cellular components of salivary glands (SG) to oxidative stress leading to SG dysfunction. However, the protective effects of antioxidants on RI-induced SG damage have not been well investigated. The authors investigated the morphometric and functional effects of epigallocatechin-3-gallate (EGCG) administered prior to RI therapy and compared this with the effects of amifostine (a well-known antioxidant) in a murine model of RI sialadenitis.Methods.Four-week-old female C57BL/6 mice (n=48) were divided into four groups; a normal control group, a RI-treated group (0.01 mCi/g mouse, orally), an EGCG and RI-treated group, and an amifostine and RI-treated group. Animals in these groups were divided into 3 subgroups and euthanized at 15, 30, and 90 days post-RI treatment. Salivary flow rates and lag times were measured, and morphologic and histologic examinations and TUNEL (terminal deoxynucleotidyl transferase biotin-dUDP nick end labeling) assays were performed. Changes in salivary 99mTc pertechnetate uptake and excretion were followed by single-photon emission computed tomography.Results.Salivary flow rates and lag times to salivation in the EGCG or amifostine groups were better than in the RI-treated group. Histologic examinations of SGs in the EGCG or amifostine group showed more mucin-rich parenchyma and less periductal fibrosis than in the RI-treated group. Fewer apoptotic cells were observed in acini, ducts, and among endothelial cells in the EGCG or amifostine group than in the RI group. In addition, patterns of 99mTc pertechnetate excretion were quite different in the EGCG or amifostine group than in the RI group.Conclusion.EGCG supplementation before RI therapy could protect from RI-induced SG damage in a manner comparable to amifostine, and thus, offers a possible means of preventing SG damage by RI.

Role of thyroid scintigraphy vs. fine needle aspiration cytology in the clinical evaluation of solitary thyroid nodule a clinicoradiopathologic study

To asses the value of qualitative and quantitative analysis of the radioisotopes 99m Tc tetrofosmin (Myoview) and 99m Tc (V) DMSA in the evaluation of malignant solitary thyroid cold nodule pre-operatively and to verify their exact value in diagnosis of differentiated thyroid carcinoma. In general there is a 5%-10% chance of malignancy in all thyroid nodules for the total population with higher incidence in single cold nodule than in multinodular goiter. The main role of 99m Tc (V) DMSA as a tumor imaging agent is in the diagnosis and follow-up of patients with medullary cancer thyroid. This work included 103 patients, 88 females and 15 males with a mean age of (37.86±13.59 years). All studied were subjected to history taking, proper clinical examination, thyroid function test profile, thyroid radioisotope imaging ( 99m Tc pertechnetate, 99m Tc tetrofosmin and 99m Tc (V) DMSA thyroid scans) and cytologic assessment of thyroid nodule proved to be cold on conventional thyroid scan. The current study combined both 99m Tc tetrofosmin and 99m Tc (V) DMSA to evaluate thyroid cold nodules and to verify possibility to differentiate between benign and malignant lesions preoperatively and as confirmed on cytology of lesions obtained by fine needle aspiration cytology (FNAC) modality. Our results showed that 99m Tc pertechnetate scan alone is not a reliable diagnostic tool to differentiate between benign and malignant thyroid nodules and that high early myoview uptake in the cold nodule is not specific for malignancy, it is also concluded that both 99m Tc tetrofosmin and 99m Tc (V) DMSA thyroid scans are valuable diagnostic tools when combined together.

99mTc-labeled HYNIC-DAPI causes plasmid DNA damage with high efficiency.

99mTc is the standard radionuclide used for nuclear medicine imaging. In addition to gamma irradiation, 99mTc emits low-energy Auger and conversion electrons that deposit their energy within nanometers of the decay site. To study the potential for DNA damage, direct DNA binding is required. Plasmid DNA enables the investigation of the unprotected interactions between molecules and DNA that result in single-strand breaks (SSBs) or double-strand breaks (DSBs); the resulting DNA fragments can be separated by gel electrophoresis and quantified by fluorescent staining. This study aimed to compare the plasmid DNA damage potential of a 99mTc-labeled HYNIC-DAPI compound with that of 99mTc pertechnetate (99mTcO4 −). pUC19 plasmid DNA was irradiated for 2 or 24 hours. Direct and radical-induced DNA damage were evaluated in the presence or absence of the radical scavenger DMSO. For both compounds, an increase in applied activity enhanced plasmid DNA damage, which was evidenced by an increase in the open circular and linear DNA fractions and a reduction in the supercoiled DNA fraction. The number of SSBs elicited by 99mTc-HYNIC-DAPI (1.03) was twice that caused by 99mTcO4 − (0.51), and the number of DSBs increased fivefold in the 99mTc-HYNIC-DAPI-treated sample compared with the 99mTcO4 − treated sample (0.02 to 0.10). In the presence of DMSO, the numbers of SSBs and DSBs decreased to 0.03 and 0.00, respectively, in the 99mTcO4 – treated samples, whereas the numbers of SSBs and DSBs were slightly reduced to 0.95 and 0.06, respectively, in the 99mTc-HYNIC-DAPI-treated samples. These results indicated that 99mTc-HYNIC-DAPI induced SSBs and DSBs via a direct interaction of the 99mTc-labeled compound with DNA. In contrast to these results, 99mTcO4 − induced SSBs via radical formation, and DSBs were formed by two nearby SSBs. The biological effectiveness of 99mTc-HYNIC-DAPI increased by approximately 4-fold in terms of inducing SSBs and by approximately 10-fold in terms of inducing DSBs.

Enteric duplication cysts in children: A target in algorithm for evaluation of lower gastrointestinal bleeding

Lower gastrointestinal bleeding (LGIB) in infants and children is a difficult diagnostic problem largely due to limitations of small-bowel evaluation. Duplication cysts are rare congenital malformations with variable clinical presentation. This report describes seven children (five boys, two girls and median age 10 [1.5-124] months) with ileal duplication cysts who presented with LGIB of varying severity from stool occult blood positivity with anemia to fresh bleeding per rectum. Diagnosis was made by Tc(99m) pertechnetate scan (n-5), balloon enteroscopy (n-1), and at laparotomy (n-1). Ultrasonography and barium meal follow-through missed the diagnosis in six and three cases, respectively. All cases underwent surgery with resection of the duplication cyst and complete removal of the mucosa containing ectopic gastric tissue while preserving adequate bowel length. A good postoperative outcome with complete symptom resolution was seen in all. Enteric duplication cyst should always be considered in children presenting with occult or overt lower gastrointestinal hemorrhage, and Tc(99m) pertechnetate scan should be done prior to invasive tests like balloon enteroscopy.

A novel oncolytic viral therapy and imaging technique for gastric cancer using a genetically engineered vaccinia virus carrying the human sodium iodide symporter

BackgroundGastric cancers have poor overall survival despite recent advancements in early detection methods, endoscopic resection techniques, and chemotherapy treatments. Vaccinia viral therapy has had promising therapeutic potential for various cancers and has a great safety profile. We investigated the therapeutic efficacy of a novel genetically-engineered vaccinia virus carrying the human sodium iodide symporter (hNIS) gene, GLV-1 h153, on gastric cancers and its potential utility for imaging with 99mTc pertechnetate scintigraphy and 124I positron emission tomography (PET).MethodsGLV-1 h153 was tested against five human gastric cancer cell lines using cytotoxicity and standard viral plaque assays. In vivo, subcutaneous flank tumors were generated in nude mice with human gastric cancer cells, MKN-74. Tumors were subsequently injected with either GLV-1 h153 or PBS and followed for tumor growth. 99mTc pertechnetate scintigraphy and 124I microPET imaging were performed.ResultsGFP expression, a surrogate for viral infectivity, confirmed viral infection by 24 hours. At a multiplicity of infection (MOI) of 1, GLV-1 h153 achieved > 90% cytotoxicity in MNK-74, OCUM-2MD3, and AGS over 9 days, and >70% cytotoxicity in MNK- 45 and TMK-1. In vivo, GLV-1 h153 was effective in treating xenografts (p < 0.001) after 2 weeks of treatment. GLV-1 h153-infected tumors were readily imaged by 99mTc pertechnetate scintigraphy and 124I microPET imaging 2 days after treatment.ConclusionsGLV-1 h153 is an effective oncolytic virus expressing the hNIS protein that can efficiently regress gastric tumors and allow deep-tissue imaging. These data encourages its continued investigation in clinical settings.

Determination of the radiochemical purity of99mTc medronate injection by thin layer chromatography on iTLC-SG: effect of medronate concentration on the value measured

When using iTLC-SG thin layer chromatography plates to measure radiochemical impurities in (99m) Tc medronate, falsely high values were obtained for (99m) Tc pertechnetate impurity. Preliminary investigations indicated that the mass of (99m) Tc medronate applied to the plate influences the value. The goal of this study was to determine if the concentration of medronate influences the value obtained for (99m) Tc pertechnetate impurity. (99m) Tc medronate was prepared at two concentrations: 4 mg/mL and 0.2 mg/mL. Impurity levels were measured using three stationary phases: dried and undried iTLC-SG and 54SFC paper. Two mobile phases were used: methyl ethyl ketone to detect (99m) Tc pertechnetate and sodium acetate 136 g/L to detect hydrolysed and colloidal (99m) Tc. Sample spot drying and volume were also investigated. With 4 mg/mL samples, the three stationary phases measured similar impurity levels (p > 0.05). With the 0.2 mg/mL samples, higher levels of (99m) Tc pertechnetate were measured with iTLC-SG than with paper (p < 0.05). Neither sample spot drying nor volume was found to affect impurity levels measured. When using iTLC-SG to measure the radiochemical purity of (99m) Tc medronate, an artefactually high level of (99m) Tc pertechnetate impurity is measured when the medronate concentration in the sample is low. The iTLC-SG stationary phase may be unsatisfactory for measuring the radiochemical purity of (99m) Tc medronate.

Study of&lt;sup&gt; 99m&lt;/sup&gt;Tc Pertechnetate Radiopharmaceuticals in Relation to Thyroid Hormone for Toxic and non-Toxic Diffuse Goiter

Abnormalities of the thyroid gland in the form of enlargement of the thyroid gland are called a goiter. Goiter is divided into two types, namely toxic and non-toxic diffuse goiter. Diagnosis could be done with thyroid scan (in vivo) and test for thyroid hormone value (in vitro). Thyroid scan is applied by giving injection of 99m Tc Pertechnetate as much as 2 - 5 mCi intravenally in the arm and then thyroid gland and salivary glands imaging were conducted in the fifth minute, tenth minute and fifteenth minute using gamma camera. Thyroid hormones test in blood is done with radioimmunoassay method. The same pattern showed the accumulation polad of the radioactive number from quotation of salivary glands. The accumulation percentage activity of 99m Tc Pertechnetate in thyroid gland for the case of toxic diffuse goiter is larger than the case of non-toxic diffuse goiter. The results of this study indicate that the predictors for the case of toxic diffuse goiter could be characterized by high thyroid uptake which the the value of T 3 hormone ≥ 3.3 ng/dl, the value of T 4 hormone ≥ 165 nmol/l, and the value of TSH hormone ≤ 0.2 μIU/ml. While the case of non-toxic diffuse goiter could be characterized by low thyroid uptake which the value of T 3 hormone ≥ 1.2 ng/dl, the value of T 4 hormone ≥ 90 nmol/l, and the value of TSH hormone ≤ 1.8 μIU/ml. Received: 14 November 2011; Revised: 18 April 2012; Accepted: 21 April 2012

Normalisation to Blood Activity Is Required for the Accurate Quantification of Na/I Symporter Ectopic Expression by SPECT/CT in Individual Subjects

The utilisation of the Na/I symporter (NIS) and associated radiotracers as a reporter system for imaging gene expression is now reaching the clinical setting in cancer gene therapy applications. However, a formal assessment of the methodology in terms of normalisation of the data still remains to be performed, particularly in the context of the assessment of activities in individual subjects in longitudinal studies. In this context, we administered to mice a recombinant, replication-incompetent adenovirus encoding rat NIS, or a human colorectal carcinoma cell line (HT29) encoding mouse NIS. We used 99mTc pertechnetate as a radiotracer for SPECT/CT imaging to determine the pattern of ectopic NIS expression in longitudinal kinetic studies. Some animals of the cohort were culled and NIS expression was measured by quantitative RT-PCR and immunohistochemistry. The radioactive content of some liver biopsies was also measured ex vivo. Our results show that in longitudinal studies involving datasets taken from individual mice, the presentation of non-normalised data (activity expressed as %ID/g or %ID/cc) leads to ‘noisy’, and sometimes incoherent, results. This variability is due to the fact that the blood pertechnetate concentration can vary up to three-fold from day to day. Normalisation of these data with blood activities corrects for these inconsistencies. We advocate that, blood pertechnetate activity should be determined and used to normalise the activity measured in the organ/region of interest that expresses NIS ectopically. Considering that NIS imaging has already reached the clinical setting in the context of cancer gene therapy, this normalisation may be essential in order to obtain accurate and predictive information in future longitudinal clinical studies in biotherapy.

ChemInform Abstract: Photoreduction of 99Tc Pertechnetate by Nanometer‐Sized Metal Oxides: New Strategies for Formation and Sequestration of Low‐Valent Technetium.

AbstractK10 (α2‐P2W17O61) is photoactivated in the presence of iPrOH to reduce 99TcO4‐ (or ReO4‐) and incorporate the reduced 99TcV (or ReV) covalently into the α2‐framework to form the 99TcVO (α2‐P2W17O61)7‐ (or ReVO (α2‐P2W17O61) 7‐) species.

Preincubation with Sn-complexes causes intensive intracellular retention of 99mTc in thyroid cells in vitro

Technetium radiopharmaceuticals are well established in nuclear medicine. Besides its well-known gamma radiation, (99m)Tc emits an average of five Auger and internal conversion electrons per decay. The biological toxicity of these low-energy, high-LET (linear energy transfer) emissions is a controversial subject. One aim of this study was to estimate in a cell model how much (99m)Tc can be present in exposed cells and which radiobiological effects could be estimated in (99m)Tc-overloaded cells. Sodium iodine symporter (NIS)-positive thyroid cells were used. (99m)Tc-uptake studies were performed after preincubation with a non-radioactive (cold) stannous pyrophosphate kit solution or as a standard (99m)Tc pyrophosphate kit preparation or with pure pertechnetate solution. Survival curves were analyzed from colony-forming assays. Preincubation with stannous complexes causes irreversible intracellular radioactivity retention of (99m)Tc and is followed by further pertechnetate influx to an unexpectedly high (99m)Tc level. The uptake of (99m)Tc pertechnetate in NIS-positive cells can be modified using stannous pyrophosphate from 3-5% to >80%. The maximum possible cellular uptake of (99m)Tc was 90Bq/cell. Compared with nearly pure extracellular irradiation from routine (99m)Tc complexes, cell survival was reduced by 3-4 orders of magnitude after preincubation with stannous pyrophosphate. Intracellular (99m)Tc retention is related to reduced survival, which is most likely mediated by the emission of low-energy electrons. Our findings show that the described experiments constitute a simple and useful in vitro model for radiobiological investigations in a cell model.

A Case of Painful Hashimoto Thyroiditis that Mimicked Subacute Thyroiditis

Hashimoto thyroiditis (HT) is an autoimmune thyroid disorder that usually presents as a diffuse, nontender goiter, whereas subacute thyroiditis (SAT) is an uncommon disease that is characterized by tender thyroid enlargement, transient thyrotoxicosis, and an elevated erythrocyte sedimentation rate (ESR). Very rarely, patients with HT can present with painful, tender goiter or fever, a mimic of SAT. We report a case of painful HT in a 68-year-old woman who presented with pain and tenderness in a chronic goiter. Her ESR was definitely elevated and her thyroid laboratory tests suggested subclinical hypothyroidism of autoimmune origin. 99mTc pertechnetate uptake was markedly decreased. Fine needle aspiration biopsy revealed reactive and polymorphous lymphoid cells and occasional epithelial cells with Hürthle cell changes. Her clinical symptoms showed a dramatic response to glucocorticoid treatment. She became hypothyroid finally and is now on levothyroxine therapy.

Microcirculatory Disorders and Choice of Treatment Strategy for the Diabetic Foot Syndrome

Radioisotope method with (99m)Tc pertechnetate is proposed for evaluation of the microcirculatory status of patients with the diabetic foot syndrome. The isotope (70-90 MBq) in 0.3-0.5 ml saline was injected subcutaneously into the interdigital spaces of the foot symmetrically on both sides. The severity of microcirculatory changes was evaluated by the rate of the radiopharmaceutical resorption using a computer-aided gamma counter. The data on the radiopharmaceutical half-resorption obtained by radioisotope study, serve as additional criteria for prediction of the disease course and choice of the treatment strategy for patients with the diabetic foot syndrome and diabetic gangrene of the lower limb.

Photoreduction of99Tc Pertechnetate by Nanometer-Sized Metal Oxides: New Strategies for Formation and Sequestration of Low-Valent Technetium

Technetium-99 ((99)Tc) (β(-)(max): 293.7 keV; t(1/2): 2.1 × 10(5) years) is a byproduct of uranium-235 fission and comprises a large component of radioactive waste. Under aerobic conditions and in a neutral-basic environment, the pertechnetate anion ((99)TcO(4)(-)) is stable. (99)TcO(4)(-) is very soluble, migrates easily through the environment and does not sorb well onto mineral surfaces, soils, or sediments. This study moves forward a new strategy for the reduction of (99)TcO(4)(-) and the chemical incorporation of the reduced (99)Tc into a metal oxide material. This strategy employs a single material, a polyoxometalate (POM), α(2)-[P(2)W(17)O(61)](10-), that can be photoactivated in the presence of 2-propanol to transfer electrons to (99)TcO(4)(-) and incorporate the reduced (99)Tc covalently into the α(2)-framework to form the (99)Tc(V)O species, (99)Tc(V)O(α(2)-P(2)W(17)O(61))(7-). This occurs via the formation of an intermediate species that slowly converts to (99)Tc(V)O(α(2)-P(2)W(17)O(61))(7-). Extended X-ray absorption fine structure and X-ray absorption near-edge spectroscopy analysis suggests that the intermediate consists of a (99)Tc(IV) α(2)- species where the (99)Tc is likely bound to two of the four W-O oxygen atoms in the α(2)-[P(2)W(17)O(61)](10-) defect. This intermediate then oxidizes and converts to the (99)Tc(V)O(α(2)-P(2)W(17)O(61))(7-) product. The reduction and incorporation of (99)TcO(4)(-) was accomplished in a "one pot" reaction using both sunlight and UV irradiation and monitored as a function of time using multinuclear nuclear magnetic resonance and radio thin-layer chromatography. The process was further probed by the "step-wise" generation of reduced α(2)-P(2)W(17)O(61)(12-) through bulk electrolysis followed by the addition of (99)TcO(4)(-). The reduction and incorporation of ReO(4)(-), as a nonradioactive surrogate for (99)Tc, does not proceed through the intermediate species, and Re(V)O is incorporated quickly into the α(2)-[P(2)W(17)O(61)](10-) defect. These observations are consistent with the periodic trends of (99)Tc and Re. Specifically, (99)Tc is more easily reduced compared to Re. In addition to serving as models for metal oxides, POMs may also provide a suitable platform to study the molecular level dynamics and the mechanisms of the reduction and incorporation of (99)Tc into a material.

Towards Quantification of Functional Breast Images Using Dedicated SPECT With Non-Traditional Acquisition Trajectories

Quantification of radiotracer uptake in breast lesions can provide valuable information to physicians in deciding patient care or determining treatment efficacy. Physical processes (e.g., scatter, attenuation), detector/collimator characteristics, sampling and acquisition trajectories, and reconstruction artifacts contribute to an incorrect measurement of absolute tracer activity and distribution. For these experiments, a cylinder with three syringes of varying radioactivity concentration, and a fillable 800 mL breast with two lesion phantoms containing aqueous (99m)Tc pertechnetate were imaged using the SPECT sub-system of the dual-modality SPECT-CT dedicated breast scanner. SPECT images were collected using a compact CZT camera with various 3D acquisitions including vertical axis of rotation, 30° tilted, and complex sinusoidal trajectories. Different energy windows around the photopeak were quantitatively compared, along with appropriate scatter energy windows, to determine the best quantification accuracy after attenuation and dual-window scatter correction. Measured activity concentrations in the reconstructed images for syringes with greater than 10 µCi /mL corresponded to within 10% of the actual dose calibrator measured activity concentration for ±4% and ±8% photopeak energy windows. The same energy windows yielded lesion quantification results within 10% in the breast phantom as well. Results for the more complete complex sinsusoidal trajectory are similar to the simple vertical axis acquisition, and additionally allows both anterior chest wall sampling, no image distortion, and reasonably accurate quantification.