Kelvin S. H. Loke

Dosimetric Considerations in Radioimmunotherapy and Systemic Radionuclide Therapies: A Review

Radiopharmaceutical therapy, once touted as the “magic bullet” in radiation oncology, is increasingly being used in the treatment of a variety of malignancies; albeit in later disease stages. With ever-increasing public and medical awareness of radiation effects, radiation dosimetry is becoming more important. Dosimetry allows administration of the maximum tolerated radiation dose to the tumor/organ to be treated but limiting radiation to critical organs. Traditional tumor dosimetry involved acquiring pretherapy planar scans and plasma estimates with a diagnostic dose of intended radiopharmaceuticals. New advancements in single photon emission computed tomography and positron emission tomography systems allow semi-quantitative measurements of radiation dosimetry thus allowing treatments tailored to each individual patient.

National Cancer Centre Singapore Consensus Guidelines for Hepatocellular Carcinoma.

Hepatocellular carcinoma (HCC) is the 6th most common cancer in the world, but the second most common cause of cancer death. There is no universally accepted consensus practice guidelines for HCC owing to rapid developments in new treatment modalities, the heterogeneous epidemiology and clinical presentation of HCC worldwide. However, a number of regional and national guidelines currently exist which reflect practice relevant to the epidemiology and collective experience of the consensus group. In 2014, clinicians at the multidisciplinary Comprehensive Liver Cancer Clinic (CLCC) at the National Cancer Centre Singapore (NCCS) reviewed the latest published scientific data and existing international and regional practice guidelines, such as those of the National Comprehensive Cancer Network, American Association for the Study of Liver Diseases and the Asian Pacific Association for the Study of the Liver, and modified them to reflect local practice. These would serve as a template by which treatment outcomes can be collated and benchmarked against international data. The NCCS Consensus Guidelines for HCC have been successfully implemented in the CLCC since their publication online on 26th September 2014, and the guidelines allow outcomes of treatment to be compared to international data. These guidelines will be reviewed periodically to incorporate new data.

The role of PET/CT in the evaluation of skeletal metastases.

Osseous metastatic disease from malignancy is a common occurrence with significant patient morbidity and mortality as well as increasing health care expenditures. Patient management plans frequently change with the identification of skeletal metastasis and the upstaging of disease status. Bone scintigraphy remains the current mainstay of diagnostic imaging procedures in nuclear medicine for the early detection of skeletal metastasis owing to their high sensitivity. Emerging positron tracers and the increasing use and availability of hybrid single-photon emission computed tomography and positron emission tomography (PET)/computed tomography machines enable physicians to diagnose metastatic disease in bones with superior accuracy. This review introduces the basics of PET and the commonly used positron tracers used to evaluate skeletal metastases.

Pancreatic metastasis detected by F-18 FDG PET/CT in a patient with breast cancer.

Pancreatic involvement by metastasis from other primaries is rare and accounts for approximately 2% to 4% of pancreatic tumors. In this article, we describe FDG-avid pancreatic involvement in a patient with diagnosis of breast cancer. We conclude that FDG PET can be a convenient noninvasive method of early detection of recurrence and in monitoring metastatic disease during follow-up in such patients. A positive FDG PET warrants histopathologic correlation for appropriate treatment.

Pseudoaneurysm and coronary abscess secondary to coronary stent fracture identified with Tc-99m hexamethylpropyleneamine oxime-labeled white blood cell SPECT/CT scintigraphy.

A radionuclide Tc-99m hexamethylpropyleneamine oxime white blood cell scan with SPECT/CT was requested for the investigation of pyrexia and bacteraemia in a 69-year-old gentleman who was status postcoronary angiography and stenting. Abnormal radiotracer activity in the region of the left anterior descending artery was observed, which on subsequent histopathology found to be a pseudoaneurysm and coronary abscess.

Gender, Race, and Age at Diagnosis as Risk Factors for Metastasis or Recurrence among 1,657 Thyroid Cancer Patients Treated with Radioiodine across 40 Years in Singapore

Background: To obtain descriptive data on Singaporean thyroid cancer patients treated with radioiodine and to assess gender, race, and age at diagnosis as risk factors for metastasis or recurrence. Methods: This is a retrospective study of all thyroid cancer patients treated with radioiodine of any prescribed activity at our institution. Data collected included: age at diagnosis, gender, race, histopathological type, duration of follow-up, and metastasis at diagnosis (locoregional or distant) or recurrence at any time. Gender, race, and age at diagnosis were analyzed for possible associations with metastasis or recurrence. Results: A total of 1,657 thyroid cancer patients were treated with radioiodine across a 40-year period; mean follow-up 6.4 ± 6.9 years (median 4.2 years). 656 (39.6%) patients had metastasis or recurrence over the duration of their follow-up. Male gender (odds ratio (OR) 1.38; p = 0.006), Malay race (OR 1.71; p < 0.0001), and age at diagnosis of > 46 years (OR 1.31; p = 0.007) were significantly associated with metastasis or recurrence. Conclusion: Male gender, Malay race, and age at diagnosis of > 46 years were significant risk factors for metastasis or recurrence in Singaporean thyroid cancer patients treated with radioiodine.

Complications of 90Y Transarterial Radioembolization of Hepatic Tumors: Primer for Interventional Radiology Residents and Fellows RadioGraphics Fundamentals | Online Presentation

This presentation provides a pictorial review of known complications related to transarterial radioembolization, focusing on their imaging appearances and prevention and management strategies.

Nuclear Medicine Imaging Artifacts

Various radiopharmaceuticals and imaging techniques are commonly used in nuclear medicine imaging to diagnose benign and malignant bone lesions. With increasing availability and utility of conventional and advanced nuclear medicine procedures, it has become necessary to know about their limitations during interpretation. Advanced fusion imaging systems, such as SPECT/CT and PET/CT, increase the complexity of inherent artifacts of individual techniques. Comprehensive quality control program and standardized scan techniques are needed to reduce the incidence and intensity of artifacts. Broadly, these artifacts can occur due to radiopharmaceutical, instrumental, and patient-related factors, and proper knowledge about them helps us to avoid misinterpretation and improve the specificity. In this chapter, we elaborate on important artifacts, how they can alter scan findings, approaches to recognize them, and ways to avoid them.