Seminars in nuclear medicine
-
Although thyroid cancer is a comparatively rare malignancy, it represents the vast majority of endocrine cancers and its incidence is increasing. Most differentiated thyroid cancers have an excellent prognosis if diagnosed early and treated appropriately. Aggressive histologic subtypes and variants carry a worse prognosis. ⋯ However, FDOPA has emerged as an alternate and more promising radiotracer in this setting. In aggressive cancers that are less amenable to treatment with (131)iodine, FDG-PET/CT may help in radiotherapy planning, and in assessing the response to radiotherapy, embolization, or experimental systemic treatments. (124)Iodine PET/CT may serve a role in obtaining lesional dosimetry for better and more rationale planning of treatment with (131)iodine. Thyroid cancer is not a monolithic disease, and different stages and histologic entities require different approaches in imaging and individualized therapy.
-
Combining the functional data provided by single-photon emission computed tomography (SPECT) with the anatomical information provided by CT has been shown to improve overall diagnostic accuracy in many areas of nuclear medicine. Although planar lung scans have often relied on correlation with a chest x-ray to help optimize scan interpretation, the advent of 3D lung imaging with SPECT provides the opportunity to combine lung perfusion data with CT images. This can be done by performing the study on a hybrid SPECT/CT scanner, with the CT acquisition typically performed with the use of low-dose parameters, rather than full diagnostic quality settings, or by software fusion with a fully diagnostic CT or a contrast-enhanced CT pulmonary angiogram. ⋯ With the increased availability of hybrid SPECT/CT scanners, such an approach can be implemented in most imaging departments with little additional acquisition time or radiation dose. Misregistration caused by respiratory motion can impact combined studies, although this can be minimized with attention to patient breathing patterns during image acquisition. For patients with lung cancer, ventilation/perfusion SPECT/CT may have a role in allowing the optimal selection of radiotherapy fields and can improve the preoperative quantification of lung function before resection.
-
Review
Food and Drug Administration requirements for testing and approval of new radiopharmaceuticals.
In March 2004, the Food and Drug Administration (FDA) published a report entitled Challenge and Opportunity on the Critical Path to New Medical Products in which it explained the critical path to medical product development and called for a nationwide effort to modernize the critical-path sciences with the aim of moving medical product development and patient care into the 21st century. The report identified medical imaging and imaging biomarkers as potential clinical development tools to facilitate medical product development and to help minimize drug attritions and development timelines. Also, in recent years, basic research on receptor-based imaging has led to an increase in the new investigational radiopharmaceuticals, many of which are in basic research stages in academic institutions. ⋯ Often, the radiopharmaceutical community is not well-informed about the regulatory pathways and scientific basis for the regulations they are subjected to. Questions, such as (1) "Do I need an investigational new drug (IND) or can I do my investigation under an RDRC (radioactive drugs research committee) oversight?" (2) "What type of information on radiopharmaceutical product quality is needed for an IND?" (3) "What level of cGMPs I am expected to operate under?" (4) "Do I need a traditional IND or can I perform studies under an exploratory IND?" (5) "What are the IND-enabling pharmacology and toxicology studies?" (6) "Is my practice consistent with pharmacy compounding or do I need to file an application with the FDA?", for example, are a source of confusion to the radiopharmaceutical community. This review provides an overview of FDA's drug development and approval process with special emphasis on radiopharmaceuticals and attempts to clarify many regulatory issues and questions by providing appropriate discussion and FDA references.
-
Review
Peptide receptor radionuclide therapy in patients with gastroenteropancreatic neuroendocrine tumors.
Somatostatin receptor imaging with [(111)In-DTPA(0))octreotide has proven its role in the diagnosis and staging of gastroenteropancreatic neuroendocrine tumors. Treatment with radiolabeled somatostatin analogues is a promising new tool in the management of patients with inoperable or metastasized, well-differentiated neuroendocrine tumors. Symptomatic improvement may occur with all (111)In, (90)Y, or (177)Lu-labeled somatostatin analogues that have been used for peptide receptor radionuclide therapy. ⋯ Finally, compared with historical controls, there is a benefit in overall survival of several years from time of diagnosis in patients treated with [(177)Lu-DOTA(0), Tyr(3)]octreotate. These data compare favorably with the limited number of alternative treatment approaches. If more widespread use of peptide receptor radionuclide therapy can be guaranteed, such therapy may well become the therapy of first choice in patients with metastasized or inoperable gastroenteropancreatic neuroendocrine tumors.
-
Review Comparative Study
Enhancing lung scintigraphy with single-photon emission computed tomography.
Although widely used for many years in the assessment of pulmonary embolism, planar ventilation-perfusion (V/Q) scintigraphy has well-recognized limitations. Single-photon emission computed tomography (SPECT) imaging, which can be readily performed in most modern nuclear medicine centers equipped with multihead gamma cameras, overcomes many of these limitations through its ability to generate 3-dimensional imaging data. V/Q SPECT has been shown to have a greater sensitivity and specificity than planar imaging and has a lower nondiagnostic rate. ⋯ It also involves significantly less radiation dose to breast tissue, an important consideration, particularly in young women. For the V/Q scan to remain relevant in the evaluation of patients with suspected pulmonary embolism, it is essential that image data are obtained so as to maximize their accuracy and diagnostic usefulness. V/Q SPECT can achieve this and, furthermore, may have a role in conditions other than pulmonary embolism, including both clinical and research fields.