Radiation Safety and External Radiation Exposure Rate of Patients Receiving I-131 Therapy for Hyperthyroidism and Remnant Ablation as Outpatient: An Institutional Experience.

Objective Our objective was to study the radiation exposure rate as function of time in the administration of radioiodine iodine-131 (I-131) for the treatment of thyrotoxicosis or Graves' disease and remnant ablation on an outpatient basis at the Department of Nuclear Medicine, and also, to study the impact of revised discharge criteria for radioiodine therapy enforced by the Atomic Energy Regulatory Board (AERB) of India. Materials and Methods This study included patients who underwent low-dose radioiodine therapy using I-131. Patients were classified into two different groups, that is, group A and group B. Group A included patients receiving low dose I-131 for the treatment of thyrotoxicosis, whereas group B included patients receiving I-131 therapy for the ablation of residual thyroid tissue after total thyroidectomy. The radiation exposure rate was measured using a radiation detector in milli roentgen per hour (mR/h) at 5 cm distance of stomach and neck levels and with the patient standing at the distance of 1 m after oral administration of I-131 at 0, 1, and 2 hours. Results A total of 134 (17 males and 117 females) patients were included in the study. Group A comprised 102 (14 male and 88 females) patients and group B of 32 (3 males and 29 females) patients. At the neck level, the average exposure rate in group A versus group B after 0, 1, and 2 hours was observed to be 6.9 versus 22.27 mR/h, 33.67 versus 43.39 mR/h, and 41.75 versus 48.90 mR/h, respectively. At the stomach level, the exposure rate was 23.65 versus 71.32 mR/h, 13.27 versus 48.45 mR/h, and 9.91 versus 39.43 mR/h after 0, 1, and 2 hours, respectively. At a distance of 1 m, the exposure rate was 1.31 versus 2.99 mR/h, 1.05 versus 2.58 mR/h, and 0.92 versus 2.21 mR/h, respectively. Conclusion Exposure rate measured for patients treated with up to 1,110 MBq (30 mCi) of I-131 was under permissible limits as per revised discharged limits, that is, 50 µSv/h (5 mR/h) prescribed by AERB, India. The patients undergoing radioiodine therapy I-131 (up to 1,110 MBq/30 mCi) can be discharged safely 2 hours postadministration following good work practice along with providing proper radiation safety instructions to patients.

Evaluation of Tetrofosmin Cold Kit Fractionation Using Alternative New Method of Quality Control for Testing Radiochemical Purity.

Objective The aim of this study is to establish a method for the fractionation of tetrofosmin cold kit under different storage conditions and to optimize an alternate chromatography method from the reference method to test radiochemical purity (RCP). Materials and Methods Tetrofosmin cold kit vial was fractionated aseptically in six equal fractions and stored in vials and syringes. To test the stability of the reconstituted solution for a longer duration, the mother vials and syringes were stored at two different temperatures, that is, at 4°C and at -20°C till further used. Radiolabeling of fractionated tetrofosmin was performed as per the standard labeling protocol. Radionuclide purity, radioassay, and pH were tested. Radiolabeling efficiency and RCP were determined by paper chromatography. Results Radionuclide purity of eluate was greater than 99.9%. The pH of technetium-99m (Tc-99m) eluate and Tc-99m tetrofosmin was between 4.5-7.5 and 7.5-9.5, respectively. The deviation in the radioactivity during all measurements was less than 1%. The kits fractioned in glass vials resulted in higher radiolabeling yield and RCP as compared with kits fractionated in syringes. The RCP of glass vial versus syringe was observed to be greater than 95 versus 90% and 95 versus 80% at -20°C and 4°C, respectively. Conclusion Tetrofosmin kit can be used in a cost-effective manner by fractionation. One tetrofosmin vial can be used in six fractions for up to 15 days when stored at -20°C and 4°C freezer temperature. The alternative method to check the RCP of Tc-99m tetrofosmin is safer and less time consuming as compared with the reference method.

Unexpected Metastasis to Breast, Lymph Node, Subcutaneous, Abdominal Wall, Intraabdominal, and Bone in Osteogenic Osteosarcoma: An Unusual Presentation on Bone Scintigraphy.

Osteogenic osteosarcoma is an aggressive malignant bone tumor with the tendency for local invasion and early metastases. Radionuclide bone scans play an important role in disease management by identifying other areas of skeletal involvement as well as extraosseous metastases. Osteogenic sarcoma metastasis is known to accumulate bone-avid agents due to their osteogenic potential. Here, we report a case of osteogenic osteosarcoma of distal femur with the absence of pleural effusion but extensive extraosseous areas of metastatic involvement in distant lymph nodes, subcutaneous planes (in the form of nodules), abdominal wall, multiple intraperitoneal deposits, breast, and bone metastases visualized on preoperative Tc-99 m methylene diphosphonate bone scan.

Efficacy of dual use of Tc-99m-pertechnetate and Tc-99m-tetrofosmin scintigraphy for the assessment of thyroid nodules.

INTRODUCTION: Radioisotope methods have shown to be useful in the non-invasive diagnosis of thyroid nodules over the past years. The present prospective study aims to evaluate the efficacy of gamma imaging using single and dual tracer using Tc-99m pertechnetate and Tc-99m tetrofosmin for evaluation and management of thyroid nodules. METHODS: Dynamic (perfusion) imaging was performed after injecting 148-185 MBq (4-5 mCi) of Tc-99m pertechnetate followed by static imaging. A second, dynamic (perfusion) imaging study within same week was performed with 296-370MBq (8-10mCi) of Tc-99m tetrofosmin on same group of patients followed by early and delayed images. Results of radionuclide perfusion scan from both studies were compared qualitatively with postsurgical histopathology or fine needle aspiration cytology (FNAC). RESULTS: Total 65 nodules in 50 patients were included in the study. With single tracer, the specificity and accuracy of Tc-99m pertechnetate was 23% and 45% and for Tc-99m tetrofosmin scan was 40% and 49%. When dual tracers were evaluated for the same group of patients, the specificity was 56% and accuracy was 55%. CONCLUSION: Dual Tracer technique with Tc-99m pertechnetate and Tc-99m tetrofosmin could be helpful in selecting nodules need surgical intervention. This technique can be used for convenient and rapid diagnostic evaluation of thyroid nodules non-invasively. We suggest a combination of fine needle aspiration biopsy and dual use of Tc-99m-pertechnetate and Tc-99m-tetrofosmin as a routine diagnostic approach to thyroid nodules.

Quality of radiochemical purity in multiple samples of various fractionated cold kits: Testing a cost & time effective technique.

OBJECTIVE: This study was aimed to assess technical aspects of fractionation of commonly used cold kits in Nuclear Medicine. MATERIALS AND METHODS: A total of 90 samples (30 samples each) of technetium-99m methylene diphosphonate (99mTc-MDP), 99mTc-diethylenetriaminepentaacetic acid (DTPA) and 99mTc-dimercaptosuccinic acid (DMSA III) were taken on various days. The radiochemical purity was calculated of each fraction of these cold kits by using paper chromatography. RESULTS: The mean value of radiochemical purity of 99mTc -MDP, 99mTc -DTPA and 99mTc-DMSA(III) were calculated as ~ 95.12%, 91.43% and 95.68% and standard deviation (SD) were ~ 5.43, 8.36 and 3.88, respectively. Maximum time in which fractionation procedure completed i.e. time required for preparing the fraction or thawing was 10 minutes. All fractionated aliquots were between 1 and 15 days. Radiopharmaceutical bio-distribution was found to be appropriate during imaging in all samples. CONCLUSION: Fractionation of cold kits using standardised technique is a time and cost-effective method and does not deteriorate the quality of labelling in commonly used pharmaceuticals in our study. We have used fractionated aliquots up to 3 days of preparation in patients with clinically usable radiochemical purity. Deep frozen fractions can be used up to 15 days in our experience.

The feasibility and safety of graded adenosine stress test for myocardial perfusion in asthmatic and/or COPD patients.

SUBJECT AND METHODS: A total of 40 patients (M:F::26:14; age range: 37-84yrs; mean: 64.1yrs) with known chronic obstructive pulmonary disease (COPD) (ranging from mild to severe), referred for a stress myocardial perfusion study, were included in this study over a period of one year. All patients underwent adenosine stress in a titrated protocol and pre-infusion of short acting bronchodilator salbutamol 2 puffs few minutes prior to start adenosine infusion. In a fraction of 26 patients, pulmonary function tests (PFT) were performed and used in addition to clinical examination to classify the severity of pulmonary obstruction. On the basis of forced expiratory volume in one second (FEV1) on PFT, 4 patients had a mild disease (FEV1 60%-80%), 17 had a moderate obstructive disease (FEV1 41%-59%) and 4 had severe COPD/asthma (FEV1 <40%) while 2 patients had normal >95% FEV1. Post-stress questionnaire to assess subjective tolerance and symptoms were undertaken for all patients. RESULTS: The results demonstrated an excellent tolerance to adenosine infusion in this group of patients, with adequate stress achieved in all. None had complaints of severe dyspnoea or respiratory distress requiring medical intervention. Thirteen patients had mild to moderate degree dyspnoea during infusion. The study included a significant number of 23 elderly patients (>65 years), who showed better tolerance than the younger patients. CONCLUSION: In this pilot study in patients with COPD who referred for myocardial perfusion scintigraphy, the feasibility and safety of adenosine in a graded protocol along with a good pre-stress assessment and a short acting bronchodilator treatment was documented.

Emerging clinical applications of PET based molecular imaging in oncology: the promising future potential for evolving personalized cancer care.

This review focuses on the potential of advanced applications of functional molecular imaging in assessing tumor biology and cellular characteristics with emphasis on positron emission tomography (PET) applications with both 18-fluorodeoxyglucose (FDG) and non-FDG tracers. The inherent heterogeneity of cancer cells with their varied cellular biology and metabolic and receptor phenotypic expression in each individual patient and also intra-and inter-lesionally in the same individual mandates for transitioning from a generalized "same-size-fits-all" approach to personalized medicine in oncology. The past two decades have witnessed improvement of oncological imaging through CT, MR imaging, PET, subsequent movement through hybrid or fusion imaging with PET/CT and single-photon emission computerized tomography (SPECT-CT), and now toward the evolving PET/MR imaging. These recent developments have proven invaluable in enhancing oncology care and have the potential to help image the tumor biology at the cellular level, followed by providing a tailored treatment. Molecular imaging, integrated diagnostics or Radiomics, biology-driven interventional radiology and theranostics, all hold immense potential to serve as a guide to give "start and stop" treatment for a patient on an individual basis. This will likely have substantial impact on both treatment costs and outcomes. In this review, we bring forth the current trends in molecular imaging with established techniques (PET/CT), with particular emphasis on newer molecules (such as amino acid metabolism and hypoxia imaging, somatostatin receptor based imaging, and hormone receptor imaging) and further potential for FDG. An introductory discussion on the novel hybrid imaging techniques such as PET/MR is also made to understand the futuristic trends.