Nuclear Medicine and Molecular Imaging

Lesion-Wise Comparison of Pre-Therapy and Post-Therapy Effective Half-Life of Iodine-131 in Pediatric and Young Adult Patients with Differentiated Thyroid Cancer Undergoing Radioiodine Therapy Abstract Purpose The effective half-life of radioiodine is an important parameter for dosimetry in differentiated thyroid cancer patients, particularly in children. We determined the pre-therapy and post-therapy effective half-life in different types of lesions, i.e., remnant, node, or lung metastases. Methods Of 84 patients recruited, 27 were < 18 years (group 1) and the remaining 57 were between 18 and 21 years (group 2). A total of 114 studies were conducted and 253 lesions were analyzed. Serial whole-body scans were acquired at 24, 48, and ≥ 72 h after administration of iodine-131. Region of interests was drawn over lesions to determine counts in the lesion. Time versus counts graphs were plotted and mono-exponentially fitted to determine effective half-life. Results The post-therapy effective half-life was found to be lesser than pre-therapy effective half-life in all types of lesions and in all groups. Median effective half-life was found maximum in intact lobe, minimum in the lung, and intermediate in remnant and nodes. In the assessment of all lesions together, pre- and post-therapy median and interquartile range (IQR) effective half-life were 59.8 (37–112) h and 48.6 (35.2–70.8) h (p < 0.0001) in group 1, 73.9 (46.2–112.7) h and 60 (57.4–85.9) h (p < 0.0001) in group 2, and 68.6 (41.53–112.36) h and 54.7 (36–80.6) h (p < 0.0001) in combined group, respectively. Importantly, the pre- and post-therapy median effective half-life serially dropped after each successive cycles of iodine-131. Conclusions There was a significant difference in pre-therapy and post-therapy effective half-life in all types of lesions. These results may have implications in calculating the correct therapeutic dose in children and in young adults.

Use of Molecular Imaging in Clinical Drug Development: a Systematic Review Abstract Background Molecular imaging such as positron emission tomography (PET) and single-photon emission computed tomography (SPECT) can provide the crucial pharmacokinetic-pharmacodynamic information of a drug non-invasively at an early stage of clinical drug development. Nevertheless, not much has been known how molecular imaging has been actually used in drug development studies. Methods We searched PubMed using such keywords as molecular imaging, PET, SPECT, drug development, and new drug, or any combination of those to select papers in English, published from January 1, 1990, to December 31, 2015. The information about the publication year, therapeutic area of a drug candidate, drug development phase, and imaging modality and utility of imaging were extracted. Results Of 10,264 papers initially screened, 208 papers met the eligibility criteria. The more recent the publication year, the bigger the number of papers, particularly since 2010. The two major therapeutic areas using molecular imaging to develop drugs were oncology (47.6%) and the central nervous system (CNS, 36.5%), in which efficacy (63.5%) and proof-of-concept through either receptor occupancy (RO) or other than RO (29.7%), respectively, were the primary utility of molecular imaging. PET was used 4.7 times more frequently than SPECT. Molecular imaging was most frequently used in phase I clinical trials (40.8%), whereas it was employed rarely in phase 0 or exploratory IND studies (1.4%). Conclusions The present study confirmed the trend that molecular imaging has been more actively employed in recent clinical drug development studies although its adoption was rather slow and rare in phase 0 studies.

Efforts in the Formation and Development of Nuclear Medicine in Vietnam Abstract The foundations of nuclear medicine in Vietnam were established from 1970. Until now, after 48 years of development, in Vietnam, we have some basic equipment including 31 SPECT, 4 SPECT/CT machines, 11 PET/CT scanners, five cyclotrons, and one nuclear reactor. Many nuclear medicine techniques in diagnosis and treatment have been routinely performed at provincial and central level health facilities such as tumor scintigraphy, thyroid scintigraphy, bone scintigraphy, kidney scintigraphy, cardiac scintigraphy, and radio-isotope therapy with I-131 and P-32. Selective internal radiation therapy with Y-90 microsphere and I-125 radioactive seed implantation has been also successfully applied in some big hospitals. However, there are still many difficulties for Vietnam as the lack of new widely used radioisotopes such as Ga-67, Cu-64, Samarium-153, and Lutetium-177 and the lack of nuclear medicine specialists. In the future, we are putting our efforts on the applications of new isotopes in diagnosis and treatment of cancers (theranostic) like Ga-68-DOTATATE, Lutetium-177-DOTATATE, Ga-68-PSMA, and Lutetium-177-PSMA, equipping modern nuclear medicine diagnostic tools, strengthening the human resources training in nuclear medicine. At the same time, we are trying our best to strengthen the cooperation with international nuclear medicine societies in over the world.

Gallbladder Paraganglioma Associated with SDHD Mutation: a Potential Pitfall on 18 F-FDOPA PET Imaging Abstract A 36-year-old male patient initially presented with hypertension, tinnitus, bilateral carotid masses, a right jugular foramen, and a periaortic arch mass with an elevated plasma dopamine level but an otherwise normal biochemical profile. On surveillance MRI 4 years after initial presentation, he was found to have a 2.2-cm T2 hyperintense lesion with arterial enhancement adjacent to the gallbladder, which demonstrated avidity on 68Ga-DOTATATE PET/CT and retrospectively on 18F-FDOPA PET/CT but was non-avid on 18F-FDG PET/CT. Biochemical work-up including plasma catecholamines, metanephrines, and chromogranin A levels were found to be within normal limits. This lesion was surgically resected and was confirmed to be a paraganglioma (PGL) originating from the gallbladder wall on histopathology. Pheochromocytoma (PHEO) and PGL are rare tumors of the autonomic nervous system. Succinate dehydrogenase subunit D (SDHD) pathogenic variants of the succinate dehydrogenase complex are usually involved in parasympathetic, extra-adrenal, multifocal head, and neck PGLs. We report an unusual location of PGL in the gallbladder associated with SDHD mutation which could present as a potential pitfall on 18F-FDOPA PET/CT as its normal excretion occurs through biliary system and gallbladder. This case highlights the superiority of 68Ga-DOTATATE in comparison to 18F-FDOPA and 18F-FDG in the detection of SDHD-related parasympathetic PGL. ClinicalTrials.gov Identifier: NCT00004847.

Tracer Accumulation in Relation to Venous Thrombus on 18 F-DOPA PET/CT in a Case of Persistent Hyperinsulinemic Hypoglycemia of Infancy Abstract 18F-DOPA PET/CT is commonly done in patients with persistent hyperinsulinemic hypoglycemia of infancy (PHHI) to look for any focal lesion in the pancreas. We present the findings in a 20-day-old neonate with PHHI who underwent 18F-DOPA PET/CT. The scan showed diffuse uptake in the pancreas with no focal lesion, physiologic excretion into the genito-urinary system, and interestingly tracer accumulation was seen in the inferior vena cava and ilio-femoral veins which is a non-physiological site for tracer accumulation. The uptake corresponded to a large venous thrombus which was confirmed by a venous Doppler.

Promotion of Nuclear Medicine-Related Sciences in Developing Countries

Theranostics in Bangladesh: Current Status, Challenges, and Future Perspective Abstract Background and Current Status of Theranostics Therapeutic nuclear medicine (NM) in Bangladesh began in the early 1980s with the application of radioactive iodine for treatment of thyroid cancer and primary hyperthyroidism. Since then, NM practice has remarkably developed in the country with the advancement of instrumentation, radiopharmacy, and information technology. The government took the initiative to establish four PET-CT centers at different NM centers, including one at the National Institute of Nuclear Medicine and Allied Sciences (NINMAS). A further development is the installation of a cyclotron center (18-MeV cyclotron) at NINMAS by the government's fund. Currently, NM is providing good health services to oncology patients throughout the country. More than 20 NM centers are functioning in different parts of the country, and therapeutic NM has an important place. However, conventional radioactive iodine still remains the major theranostic application. Challenges and Future Perspective The expansion and development of therapeutic NM for other cancers have been limited due to a number of challenging factors. A brief overview of the history and current status of NM in Bangladesh is presented here with an examination of factors that pose as obstacles to the introduction and development of new therapeutic technologies. Finally, future perspectives are discussed with ways to mitigate existing problems and challenges.

Nuclear Theranostics in Taiwan Abstract Boron neutron capture therapy and Y-90 radioembolization are emerging therapeutic methods for uncontrolled brain cancers and hepatic cancers, respectively. These advanced radiation therapies are heavily relied on theranostic nuclear medicine imaging before the therapy for the eligibility of patients and the prescribed-dose simulation, as well as the post-therapy scanning for assessing the treatment efficacy. In Taiwan, the Taipei Veterans General Hospital is the only institute performing the BNCT and also the leading institute performing Y-90 radioembolization. In this article, we present our single institute experiences and associated theranostic nuclear medicine approaches for these therapies.

Development of Predictive Models in Patients with Epiphora Using Lacrimal Scintigraphy and Machine Learning Abstract Purpose We developed predictive models using different programming languages and different computing platforms for machine learning (ML) and deep learning (DL) that classify clinical diagnoses in patients with epiphora. We evaluated the diagnostic performance of these models. Methods Between January 2016 and September 2017, 250 patients with epiphora who underwent dacryocystography (DCG) and lacrimal scintigraphy (LS) were included in the study. We developed five different predictive models using ML tools, Python-based TensorFlow, R, and Microsoft Azure Machine Learning Studio (MAMLS). A total of 27 clinical characteristics and parameters including variables related to epiphora (VE) and variables related to dacryocystography (VDCG) were used as input data. Apart from this, we developed two predictive convolutional neural network (CNN) models for diagnosing LS images. We conducted this study using supervised learning. Results Among 500 eyes of 250 patients, 59 eyes had anatomical obstruction, 338 eyes had functional obstruction, and the remaining 103 eyes were normal. For the data set that excluded VE and VDCG, the test accuracies in Python-based TensorFlow, R, multiclass logistic regression in MAMLS, multiclass neural network in MAMLS, and nuclear medicine physician were 81.70%, 80.60%, 81.70%, 73.10%, and 80.60%, respectively. The test accuracies of CNN models in three-class classification diagnosis and binary classification diagnosis were 72.00% and 77.42%, respectively. Conclusions ML-based predictive models using different programming languages and different computing platforms were useful for classifying clinical diagnoses in patients with epiphora and were similar to a clinician's diagnostic ability.

Theranostics in India: a Particularly Exquisite Concept or an Experimental Tool Abstract The term theranostics is a combination of a diagnostic tool that helps to define a right therapeutic tool for specific disease and paves the approach towards personalized or precision medicine. In Nuclear Medicine, a diagnostic radionuclide is labeled with the target and once expression is documented, the same target is labeled with a therapeutic radionuclide and treatment is executed. The theranostic concept was applied first time in 1964 in the treatment of thyroid cancer with I-131 (RAI). Over the years, other theranostic radiotracers became available indigenously from the Bhabha Atomic Research Centre (BARC) in the country. Currently Lu-177 is produced in India and peptides like DOTATATE and PSMA are available in a kit form indigenously. At the present time, the radionuclide therapies of oncological disorders which are being performed in India are mainly for neuroendocrine tumors (NET) and metastatic castration resistant prostate cancer (mCRPC). The main constraints pertaining to this concept is the cost of treatment and awareness among the clinicians which are gradually being taken care of by the private health insurance and our participation in disease management group meetings respectively. The theranostic concept has become popular over the years and has the potential for sustained growth.