Reduction in radiation dose in mercaptoacetyltriglycerine renography with enhanced planar processing.

PURPOSE: To determine the minimum dose of technetium 99m ((99m)Tc) mercaptoacetyltriglycerine (MAG3) needed to perform dynamic renal scintigraphy in the pediatric population without loss of diagnostic quality or accurate quantification of renal function and to investigate whether adaptive noise reduction could help further reduce the minimum dose required. MATERIALS AND METHODS: Approval for this retrospective study was obtained from the institutional review board, with waiver of informed consent. A retrospective review was conducted in 33 pediatric patients consecutively referred for a (99m)Tc-MAG3 study. In each patient, a 20-minute dynamic study was performed after administration of 7.4 MBq/kg. Binomial subsampling was used to simulate studies performed with 50%, 30%, 20%, and 10% of the administered dose. Four nuclear medicine physicians independently reviewed the original and subsampled images, with and without noise reduction, for image quality. Two observers independently performed a quantitative analysis of renal function. Subjective rater confidence was analyzed by using a logistic regression model, and the quantitative analysis was performed by using the paired Student t test. RESULTS: Reducing the administered dose to 30% did not substantially affect image quality, with or without noise reduction. When the dose was reduced to 20%, there was a slight but significant decrease (P = .0074) in image quality, which resolved with noise reduction. Reducing the dose to 10% caused a decrease in image quality (P = .0003) that was not corrected with noise reduction. However, the dose could be reduced to 10% without a substantial change in the quantitative evaluation of renal function independent of the application of noise reduction. CONCLUSION: Decreasing the dose of (99m)Tc-MAG3 from 7.4 to 2.2 MBq/kg did not compromise image quality. With noise reduction, the dose can be reduced to 1.5 MBq/kg without subjective loss in image quality. The quantitative evaluation of renal function was not substantially altered, even with a theoretical dose as low as 0.74 MBq/kg.

Iodine-131-labeled meta-iodobenzylguanidine therapy of children with neuroblastoma: program planning and initial experience.

Patients with high-risk neuroblastoma have a poor prognosis, especially in cases of recurrent or relapsed disease. Iodine-131-labeled meta-iodobenzylguanidine ((131)I-MIBG) can be an effective and relatively well-tolerated agent for the treatment of refractory neuroblastoma. Establishing an MIBG therapy program requires a great deal of planning, availability of hospital resources, and the commitment of individuals with training and expertise in multiple disciplines. Providing (131)I-MIBG therapy requires physical facilities and procedures that permit patient care in compliance with the standards for occupational and community exposure to radiation. Establishment of a successful (131)I-MIBG therapy program also requires a detailed operational plan and appropriate education for caregivers, parents, and patients.

Nuclear medicine in the first year of life.

Nuclear medicine has an important role in the care of newborns and children less than 1 y old. Patients in this age group present with a spectrum of diseases different from those of older children or adults. These patients can benefit from the full range of nuclear medicine studies. In these young children, nuclear medicine studies are more likely to be used to evaluate a wide range of congenital conditions but also can be helpful for evaluating acquired conditions such as infection, cancer, and trauma. This review first will cover the general aspects of nuclear medicine practice with these patients, including the special considerations that can help achieve successful diagnostic imaging. These topics will include clinical indications, imaging technology, instrumentation, software, positioning and immobilization, sedation, local and general anesthesia, radiopharmaceutical doses, radiation risk, and dose reduction. The review then will discuss the specific nuclear medicine studies that typically are obtained in patients in this age group. With extra care and attention to the special needs of this population, nuclear medicine departments can successfully study patients less than 1 y old.

Administered radiopharmaceutical doses in children: a survey of 13 pediatric hospitals in North America.

UNLABELLED: Universally applied standards for administering radiopharmaceutical doses in children do not presently exist. Hence, pediatric radiopharmaceutical dosimetry varies considerably from institution to institution and is generally based on the recommended adult dose adjusted for body mass. METHODS: We surveyed 13 pediatric hospitals in North America to obtain objective data on dosimetry practices for 16 pediatric nuclear medicine examinations, including the minimum total radiopharmaceutical administered dose per examination, the total administered dose based on body mass, and maximum total doses in children. RESULTS: The reported administered doses of radiopharmaceuticals to children vary over a relatively large range, especially with respect to minimum total administered doses. CONCLUSION: This survey has identified a broad range of administered doses directly leading to variability in radiation-absorbed doses to patients. The nuclear medicine community should develop pediatric standards for radiopharmaceutical administered doses and reduce radiation exposure in children, such as through the use of modern software reconstruction techniques.

Skeletal PET with 18F-fluoride: applying new technology to an old tracer.

Although (18)F-labeled NaF was the first widely used agent for skeletal scintigraphy, it quickly fell into disuse after the introduction of (99m)Tc-labeled bone-imaging agents. Recent comparative studies have demonstrated that (18)F-fluoride PET is more accurate than (99m)Tc-diphosphonate SPECT for identifying both malignant and benign lesions of the skeleton. Combining (18)F-fluoride PET with other imaging, such as CT, can improve the specificity and overall accuracy of skeletal (18)F-fluoride PET and probably will become the routine clinical practice for (18)F-fluoride PET. Although (18)F-labeled NaF and (99m)Tc-diphosphonate have a similar patient dosimetry, (18)F-fluoride PET offers shorter study times (typically less than 1 h), resulting in a more efficient workflow, improved patient convenience, and faster turnarounds of reports to the referring physicians. With the widespread availability of PET scanners and the improved logistics for the delivery of (18)F radiopharmaceuticals, prior limitations to the routine use of (18)F-fluoride bone imaging have largely been overcome. The favorable imaging performance and the clinical utility of (18)F-fluoride PET, compared with (99m)Tc-diphosphonate scintigraphy, support the reconsideration of (18)F-fluoride as a routine bone-imaging agent.