Phenotyping Pain in Patients With Fibrous Dysplasia/McCune-Albright Syndrome.

CONTEXT: Pain is a poorly managed aspect in fibrous dysplasia/McCune-Albright syndrome (FD/MAS) because of uncertainties regarding the clinical, behavioral, and neurobiological underpinnings that contribute to pain in these patients. OBJECTIVE: Identify neuropsychological and neurobiological factors associated with pain severity in FD/MAS. DESIGN: Prospective, single-site study. PATIENTS: Twenty patients with FD/MAS and 16 age-sex matched healthy controls. INTERVENTION: Assessments of pain severity, neuropathic pain, pain catastrophizing (pain rumination, magnification, and helplessness), emotional health, and pain sensitivity with thermal quantitative sensory testing. Central nervous system (CNS) properties were measured with diffusion tensor imaging, structural magnetic resonance imaging, and functional magnetic resonance imaging. MAIN OUTCOME MEASURES: Questionnaire responses, detection thresholds and tolerances to thermal stimuli, and structural and functional CNS properties. RESULTS: Pain severity in patients with FD/MAS was associated with more neuropathic pain quality, higher levels of pain catastrophizing, and depression. Quantitative sensory testing revealed normal detection of nonnoxious stimuli in patients. Individuals with FD/MAS had higher pain tolerances relative to healthy controls. From neuroimaging studies, greater pain severity, neuropathic pain quality, and psychological status of the patient were associated with reduced structural integrity of white matter pathways (superior thalamic radiation and uncinate fasciculus), reduced gray matter thickness (pre-/paracentral gyri), and heightened responses to pain (precentral, temporal, and frontal gyri). Thus, properties of CNS circuits involved in processing sensorimotor and emotional aspects of pain were altered in FD/MAS. CONCLUSION: These results offer insights into pain mechanisms in FD/MAS, while providing a basis for implementation of comprehensive pain management treatment approaches that addresses neuropsychological aspects of pain.

Use of intraoperative bone scintigraphy for resection of spinal osteoid osteoma.

BACKGROUND: The location and proximity to the spinal cord in spinal osteoid osteoma can increase the likelihood of an incomplete resection. Intraoperative bone scintigraphy (IOBS) can be used to verify location and complete surgical resection. OBJECTIVE: To review our experience using IOBS for resection of intraspinal osteoid osteoma. METHODS: IRB approved, retrospective review of IOBS-guided resection over 10 years. Patients underwent injection of 200 uCi/kg (1-20 mCi) 99mTc-MDP 3-4 h prior surgery. Portable single-headed gamma camera equipped with a pinhole collimator (3- or 4-mm aperture) was used. Images were obtained pre-operatively, at the start of the procedure, and intraoperatively. Operative notes were reviewed. Evaluation of recurrence and clinical follow-up was performed. RESULTS: Twenty IOBS-guided resections were performed in 18 patients (median age 13.5 years, 6-22 years, 12 males). Size ranged 5-16 mm, with 38.9% (7/18) cervical, 22.2% (4/18) thoracic, 22.2% (4/18) lumbar, and 16.7% (3/18) sacral. In all cases, IOBS was able to localize the lesion. After suspected total excision, IOBS altered the surgical plan in 75% of cases (15/20), showing residual activity prompting further resection. Median length of follow-up was 6 months (range 1-156 months) with 90% (18/20) showing complete resection without recurrence. Two patients had osteoid osteoma recurrence at 7 and 10 months following the original resection, requiring re-intervention. CONCLUSIONS: IOBS is a useful tool for real-time localization and assessment of spinal osteoid osteoma resection. In all cases, IOBS was able to localize the lesion and changed surgical planning in 75% of cases. Ninety percent of patients achieved complete resection and remain recurrence free.

68 Ga-DOTATATE PET and functional imaging in pediatric pheochromocytoma and paraganglioma.

Pheochromocytoma and paraganglioma (PPGL) are rare neuroendocrine tumors in childhood. Up to 40% of PPGL are currently thought to be associated with a hereditary predisposition. Nuclear medicine imaging modalities such as fluorodeoxyglucose positron emission tomography (18 F-FDG PET), 68 Ga-DOTATATE PET, and 123 I-metaiodobenzylguanidine (123 I-MIBG) scintigraphy play an essential role in the staging, response assessment, and determination of suitability for targeted radiotherapy in patients with PPGL. Each of these functional imaging modalities targets a different cellular characteristic and as such can be complementary to anatomic imaging and to each other. With the recent US Food and Drug Administration approval and increasing use of 68 Ga-DOTATATE for imaging in children, the purpose of this article is to use a case-based approach to highlight both the advantages and limitations of DOTATATE imaging as it is compared to current radiologic imaging techniques in the staging and response assessment of pediatric PPGL, as well as other neuroendocrine malignancies.

Case Report: The Imperfect Association Between Craniofacial Lesion Burden and Pain in Fibrous Dysplasia.

Patients with fibrous dysplasia (FD) often present with craniofacial lesions that affect the trigeminal nerve system. Debilitating pain, headache, and migraine are frequently experienced by FD patients with poor prognosis, while some individuals with similar bone lesions are asymptomatic. The clinical and biological factors that contribute to the etiopathogenesis of pain in craniofacial FD are largely unknown. We present two adult females with comparable craniofacial FD lesion size and location, as measured by 18F-sodium fluoride positron emission tomography/computed tomography (PET/CT), yet their respective pain phenotypes differed significantly. Over 4 weeks, the average pain reported by Patient A was 0.4/0-10 scale. Patient B reported average pain of 7.8/0-10 scale distributed across the entire skull and left facial region. Patient B did not experience pain relief from analgesics or more aggressive treatments (denosumab). In both patients, evaluation of trigeminal nerve divisions (V1, V2, and V3) with CT and magnetic resonance imaging (MRI) revealed nerve compression and displacement with more involvement of the left trigeminal branches relative to the right. First-time employment of diffusion MRI and tractography suggested reduced apparent fiber density within the cisternal segment of the trigeminal nerve, particularly for Patient B and in the left hemisphere. These cases highlight heterogeneous clinical presentation and neurobiological properties in craniofacial FD and also, the disconnect between peripheral pathology and pain severity. We hypothesize that a detailed phenotypic characterization of patients that incorporates an advanced imaging approach probing the trigeminal system may provide enhanced insights into the variable experiences with pain in craniofacial FD.

Case Report: A Neuro-Ophthalmological Assessment of Vision Loss in a Pediatric Case of McCune-Albright Syndrome.

Patients diagnosed with McCune-Albright Syndrome (MAS) frequently manifest craniofacial fibrous dysplasia (FD). Craniofacial FD can impinge nerve fibers causing visual loss as well as craniofacial pain. Surgical decompression of affected nerves is performed, with variable efficacy, in an attempt to restore function or alleviate symptoms. Here, we present a case of a 12-year-old MAS patient with visual deficits, particularly in the left eye (confirmed by enlarged blind spots on Goldmann visual field testing), and craniofacial pain. Decompression surgery of the left optic nerve mildly improved vision, while persistent visual deficits were noted at a 3-month follow-up assessment. An in-depth, imaging-based evaluation of the visual system, including the retinal nerve fiber layer, optic nerves, and central nervous system (CNS) visual pathways, revealed multiple abnormalities throughout the visual processing stream. In the current FD/MAS patient, a loss of white matter fiber density within the left optic radiation and functional changes involving the left primary visual cortex were observed. Aberrant structural and functional abnormalities embedded within central visual pathways may play a role in facilitating deficits in vision in FD/MAS and contribute to the variable outcome following peripheral nerve decompression surgery.

Development and autoregulation of kidney function in children: a retrospective study using 99mTc-MAG3 renography.

BACKGROUND: Both the development of kidney function in healthy children and autoregulation ability of kidney function in patients with asymmetric kidneys are important in clinical diagnosis and treatment of kidney-related diseases, but there are however only limited studies. This study aimed to investigate development of kidney function in normal children with healthy symmetric kidneys and autoregulation of the healthy kidney compensating the functional loss of a diseased one in children with asymmetric kidneys. METHODS: Two hundred thirty-seven children (156 male, 81 female) from 0 to 20y (average 4.6y ± 5.1) undergoing 99mTc-MAG3 renography were included, comprising 134 with healthy symmetrically functioning kidneys and 103 with asymmetric kidneys. Clearance was calculated from kidney uptakes at 1-2 min. A developmental model between MAG3 clearance (CL) and patient age in normal group was identified (CL = 84.39Age0.395 ml/min, r = 0.957, p < 0.001). The clearance autoregulation rate in abnormal group with asymmetric kidneys was defined as the ratio of the measured MAG3 clearance and the normal value predicted from the renal developmental model of normal group. RESULTS: No significant difference of MAG3 clearance (p = 0.723) was found between independent abnormal group and normal group. The autoregulation rate of kidney clearance in abnormal group was 94.2% on average, and no significant differences were found between two age groups (p = 0.49), male and female (p = 0.39), and left kidney and right kidney (p = 0.92) but two different grades of asymmetric kidneys (p = 0.02). CONCLUSIONS: The healthy kidney of two asymmetric kidneys can automatically regulate total kidney function up to 94% of two symmetric kidneys in normal children.

Pediatric Solid Gastric Emptying Scintigraphy: Normative Value Guidelines and Nonstandard Meal Alternatives.

INTRODUCTION: Adult standards for gastric emptying scintigraphy, including the type of meal and range of normative values for percent gastric emptying, are routinely used in pediatric practice, but to date have not been validated. The purpose of this study is to determine whether the use of adult criteria for gastric emptying scintigraphy is valid for children and whether alternative nonstandard meals can also be offered based on these criteria. METHODS: This retrospective study analyzed patients (n = 1,151 total) who underwent solid-phase gastric emptying scintigraphy. Patients were stratified into normal and delayed gastric emptying cohorts based on adult criteria, i.e., with normal gastric emptying defined as ≤10% gastric retention at 4 hours. Patients were further stratified based on the type of meal, namely complete or partial adult standard meals or alternative cheese-based meals. Percent gastric retention values at 1, 2, 3, and 4 hours were compared. RESULTS: The median (95% upper reference limit) percentage gastric retention values for the complete standard meal were 72% (93%) at 1 hour, 39% (65%) at 2 hours, 15% (33%) at 3 hours, and 6% (10 %) at 4 hours. By comparison, the values for cheese-based meals were 60% (87%) at 1 hour, 29% (61%) at 2 hours, 10% (30%) at 3 hours, and 5% (10%) at 4 hours. Consumption of at least 50% of the standard meal yielded similar retention percentages; 68% (89%) at 1 hour, 32% (57%) at 2 hours, 10% (29%) at 3 hours, and 5% (10%) at 4 hours. There were no significant age- or sex-specific differences using the adult criteria. DISCUSSION: The adult normative standards for gastric emptying scintigraphy are applicable for use in the pediatric population. These same standards can be also be applied to nonstandard meal options, including cheese-based alternative meals and partial standard meals.

How we read pediatric PET/CT: indications and strategies for image acquisition, interpretation and reporting.

PET/CT plays an important role in the diagnosis, staging and management of many pediatric malignancies. The techniques for performing PET/CT examinations in children have evolved, with increasing attention focused on reducing patient exposure to ionizing radiation dose whenever possible and minimizing scan duration and sedation times, with a goal toward optimizing the overall patient experience. This review outlines our approach to performing PET/CT, including a discussion of the indications for a PET/CT exam, approaches for optimizing the exam protocol, and a review of different approaches for acquiring the CT portion of the PET/CT exam. Strategies for PACS integration, image display, interpretation and reporting are also provided. Most practices will develop a strategy for performing PET/CT that best meets their respective needs. The purpose of this article is to provide a comprehensive overview for radiologists who are new to pediatric PET/CT, and also to provide experienced PET/CT practitioners with an update on state-of-the art CT techniques that we have incorporated into our protocols and that have enabled us to make considerable improvements to our PET/CT practice.

Stomach frame-count-based attenuation correction of dynamic posterior view gastric emptying scintigraphy with continuous acquisition in children.

BACKGROUND: When performing dynamic gastric emptying scintigraphy with continuous acquisition in children, a single posterior view acquisition is preferred because it allows the young patient to more easily interact with a parent or technologist even though this method tends toward overestimating gastric emptying. OBJECTIVES: The objective of our study was to develop a new attenuation correction (AC) method to improve the accuracy of the time activity curve and the measurement of residual gastric emptying from 1-h posterior images of gastric emptying scintigraphy with continuous acquisition. MATERIALS AND METHODS: We developed a frame-count-based AC for gastric emptying scintigraphy from the posterior view (posterior AC method). We retrospectively reviewed 122 gastric emptying studies performed in children using conjugated posterior and anterior views, and evaluated the statistical differences between posterior only (without AC) and posterior AC using the geometric mean method as a reference standard. RESULTS: The residual values obtained using posterior AC were not significantly different (P=0.813) compared to those using the geometric mean while the values using the posterior only were significantly different (P<0.001) from the geometric mean. CONCLUSION: The proposed method can replace the geometric mean method to estimate gastric emptying residual fraction using patient-friendly posterior view without a significant difference in 1-h gastric emptying scintigraphy with continuous acquisition.

Nuclear Medicine Techniques in Pediatric Bone Imaging.

An important mandate when imaging pediatric patients is the reduction of radiation exposure to the lowest possible level consistent with good quality diagnostic imaging, so individual selection of radiopharmaceutical dosage and imaging technique is essential. Although the logistics of image acquisition and the approach to interpretation mirror the more common use in adults, the challenges of imaging young children typically require greater attention to patient preparation, positioning, and supervision during imaging, with the use of parental or family engagement in the procedure, gentle restraint, and occasionally the need for sedation. Because the normal bone scan appearance varies dramatically with age as osseous structures mature, it is critical that the interpreting physician be well versed in the range of normal variability at each developmental stage. Although routinely employed in the evaluation of malignancy, radionuclide bone imaging in children is used for a much wider range of benign disorders than it is typical in adults. In many pediatric nuclear medicine departments, the evaluation of benign bone disorders represents most imaging procedures. Common indications include the evaluation of sports injuries, osteomyelitis, trauma, including suspected child abuse, growth disorders, such as mandibular condyle asymmetry, and noninfectious processes such as Langerhans cell histiocytosis. Both planar scintigraphy and SPECT imaging are widely employed, although the SPECT acquisition time presents a barrier in some age groups, making shorter planar spot views desirable when feasible. PET bone imaging with 18F-sodium fluoride has been shown useful in a number of pediatric disorders, but may present issues in young children, as it can require the use of sedation. Despite this challenge, the higher resolution and resulting better anatomical depiction of bone anatomy by PET techniques can be very valuable in evaluating small structures, and current experience suggests a large future role for fluoride PET imaging.

Features and Outcome of Autonomous Thyroid Nodules in Children: 31 Consecutive Patients Seen at a Single Center.

CONTEXT: Most thyroid nodules are benign and their accurate identification can avoid unnecessary procedures. In adult patients, documentation of nodule autonomy is accepted as reassurance of benign histology and as justification to forgo biopsy or thyroidectomy. In contrast, the negative predictive value of nodule autonomy in children is uncertain. Some recent publications recommend surgical resection as initial management, but few address the degree of TSH suppression or the specific scintigraphic criteria used to diagnose autonomy. OBJECTIVE: The objective of the study was to study the presenting features and cancer risk of children with autonomous nodules. DESIGN AND SETTING: Medical records of all 31 children diagnosed with autonomous nodules at our center from 2003 to 2014 were retrospectively reviewed. PATIENTS AND RESULTS: All children met full diagnostic criteria for autonomous nodules, defined by both autonomous 123I uptake into the nodule and the suppression of uptake in the normal thyroid parenchyma on scintigraphy performed during hypothyrotropinemia. The median age of presentation was 15 years (range 3-18 y) with a female to male ratio of 15:1. Fifty-eight percent of patients had solitary nodules and 42% had multiple nodules. The median size of each patient's largest autonomous nodule was 39 mm (range 18-67 mm). Most of the children in this series (68%) had diagnostic biopsies and/or operative pathology of their largest autonomous nodule, which showed benign cytology or histology in all cases. CONCLUSIONS: In this pediatric series, the cancer rate observed in biopsied or resected autonomous nodules was 0%. Whereas larger studies are needed to confirm our findings, these results agree with earlier reports suggesting that thyroid cancer is rare in rigorously defined autonomous nodules and support that conservative management may be offered to selected children who meet strict diagnostic criteria for autonomous nodules, deferring definitive therapies until adulthood when the risks of thyroidectomy and 131I ablation are lower.

Evaluation of Primary Pulmonary Vein Stenosis in Children: Comparison of Radionuclide Perfusion Lung Scan and Angiography.

OBJECTIVE: The purpose of this study was to evaluate the utility of radionuclide perfusion lung scanning in the evaluation of primary pulmonary vein stenosis (PVS) in pediatric patients by comparing it with angiography. MATERIALS AND METHODS: We retrospectively identified pediatric patients with primary PVS who underwent both lung scanning and angiography. A cohort of 34 patients was evaluated. The presence of PVS in the right upper, right lower, left upper, and left lower pulmonary veins on angiograms was recorded. Two nuclear medicine physicians evaluated the lung scans for perfusion defects. Agreement between lung scan and angiographic findings was assessed with contingency tables. Sensitivity and specificity of lung scanning for accurate detection of PVS with angiographic findings as the reference standard were assessed by ROC analysis. RESULTS: Angiography depicted PVS in 90 of the total 136 pulmonary veins (66%). Lung scans correctly depicted 65 (72%) of the cases of PVS diagnosed with angiography. The sensitivity and specificity of lung scans were 76.0% and 88.9% for the right upper pulmonary vein, 70.6% and 94.1% for the right lower pulmonary vein, 77.3% and 58.3% for the left upper pulmonary vein, and 65.4% and 87.5% for the left lower pulmonary vein. CONCLUSION: Lung scan findings correlate with angiographic findings in the detection of primary PVS in pediatric patients. Perfusion lung scanning may have a role in angiographically diagnosed PVS by noninvasively showing relative perfusion at the tissue level.

Radiation doses for pediatric nuclear medicine studies: comparing the North American consensus guidelines and the pediatric dosage card of the European Association of Nuclear Medicine.

BACKGROUND: Estimated radiation dose is important for assessing and communicating the risks and benefits of pediatric nuclear medicine studies. Radiation dose depends on the radiopharmaceutical, the administered activity, and patient factors such as age and size. Most radiation dose estimates for pediatric nuclear medicine have not been based on administered activities of radiopharmaceuticals recommended by established practice guidelines. The dosage card of the European Association of Nuclear Medicine (EANM) and the North American consensus guidelines each provide recommendations of administered activities of radiopharmaceuticals in children, but there are substantial differences between these two guidelines. OBJECTIVE: For 12 commonly performed pediatric nuclear medicine studies, two established pediatric radiopharmaceutical administration guidelines were used to calculate updated radiation dose estimates and to compare the radiation exposure resulting from the recommendations of each of the guidelines. MATERIALS AND METHODS: Estimated radiation doses were calculated for 12 common procedures in pediatric nuclear medicine using administered activities recommended by the dosage card of the EANM (version 1.5.2008) and the 2010 North American consensus guidelines for radiopharmaceutical administered activities in pediatrics. Based on standard models and nominal age-based weights, radiation dose was estimated for typical patients at ages 1, 5, 10 and 15 years and adult. The resulting effective doses were compared, with differences greater than 20% considered significant. RESULTS: Following either the EANM dosage card or the 2010 North American guidelines, the highest effective doses occur with radiopharmaceuticals labeled with fluorine-18 and iodine-123. In 24% of cases, following the North American consensus guidelines would result in a substantially higher radiation dose. The guidelines of the EANM dosage card would lead to a substantially higher radiation dose in 39% of all cases, and in 62% of cases in which patients were age 5 years or younger. CONCLUSION: For 12 commonly performed pediatric nuclear medicine studies, updated radiation dose estimates can guide efforts to reduce radiation exposure and provide current information for discussing radiation exposure and risk with referring physicians, patients and families. There can be substantial differences in radiation exposure for the same procedure, depending upon which of these two guidelines is followed. This discordance identifies opportunities for harmonization of the guidelines, which may lead to further reduction in nuclear medicine radiation doses in children.

Beyond current guidelines: reduction in minimum administered radiopharmaceutical activity with preserved diagnostic image quality in pediatric hepatobiliary scintigraphy.

PURPOSE: To determine if the minimum administered radiopharmaceutical activity for hepatobiliary scintigraphy can be reduced while preserving diagnostic image quality using enhanced planar processing (EPP). METHODS: A total of 40 infants between 10 and 270 days old (body mass 2.2 - 6.5 kg) had hepatobiliary scintigraphy during the period 2004 - 2010 following the intravenous administration of either (99m)Tc-mebrofenin (18 patients) or (99m)Tc-disofenin (22 patients). Due to the small size of these patients, they all received the minimum administered activity of 18.5 MBq consistent with the North American Consensus Guidelines. Six nuclear medicine physicians subjectively graded the acceptability of the image quality for clinical interpretation using a four-point scale (not acceptable, fair, good, excellent). Each physician independently graded seven image sets including the original study (full activity) and simulated reduced activity studies using binomial subsampling (50% of full activity, 25% of full activity and activity reduced by weight), with and without EPP. RESULTS: For full-activity studies, 98% were deemed acceptable by the six physicians for clinical interpretation. The percentages of acceptable 50% reduced activity studies with and without EPP were not significantly different from the percentage of acceptable full-activity studies (P = 0.193 and P = 0.998, respectively). The percentage of acceptable 25% reduced activity studies without EPP was significantly different from the percentage of acceptable full-activity studies (P < 0.001); however, this difference vanished when EPP was applied (P = 0.482). The activity reduced by weight ranged from 1.85 to 4.81 MBq (10% to 26% of full dose) and the percentages of acceptable studies with and without EPP were significantly different from the percentage of acceptable full-activity studies (P < 0.001 and P = 0.02, respectively). CONCLUSION: Clinically interpretable hepatobiliary scintigraphy images can be obtained in infants when the minimum administered activity is substantially reduced. Without EPP, clinically acceptable images may be produced with a reduction of 50%, and with EPP, a reduction of 75% or more may be possible.

Utility of salivagram in pulmonary aspiration in pediatric patients: comparison of salivagram and chest radiography.

OBJECTIVE: The purpose of our study was to correlate the results of the radionuclide salivagram with the corresponding chest radiography findings on patients being evaluated for salivary aspiration to determine the utility of the salivagram. MATERIALS AND METHODS: We identified 222 patients younger than 21 years who underwent salivagram and chest radiography within 3 months of each other. Salivagrams were blindly interpreted by two readers and chest radiographs were blindly interpreted by two other readers. The kappa coefficient with 95% CI was used to measure the level of interobserver agreement. Multivariate logistic regression was applied to determine whether age, sex, and neurologic diagnosis were predictors of a positive salivagram, with the odds ratio used to estimate association. RESULTS: Interobserver agreement on salivagram interpretation was excellent (κ = 0.988; p < 0.0001; 95% CI, 0.968-1.000). Interobserver agreement on chest radiography interpretation was excellent (κ = 0.905; p < 0.0001; 95% CI, 0.845-0.965). The salivagram was positive for aspiration in 55 patients (25%). Chest radiography was positive in 54 patients (24%). When the interpretations of the salivagram (normal or abnormal) were compared with interpretations of the chest radiograph (normal or abnormal), there were 213 agreements and nine disagreements (intermethod agreement κ = 0.891; p < 0.0001; 95% CI, 0.831-0.952). Independent of age (p = 0.80) and sex (p = 0.31), patients with a neurologic diagnosis had odds of a positive salivagram 5.6 times higher than other diagnoses (odds ratio = 5.6; 95% CI, 2.5-13.1; p < 0.0001). CONCLUSION: Infants with abnormal findings on salivagrams also had a high rate of abnormal findings on chest radiographs, which may indicate that some of the lung disease may be due to aspirated saliva. Salivagrams may be useful in children at risk of aspiration to identify those in whom intervention may help minimize the consequences of aspiration.

Gastric emptying in children: what is the best acquisition method?

OBJECTIVES: The geometric mean is the recommended method for calculating gastric emptying in adults to correct for variable attenuation during the study. In children, it has been reported that a single posterior acquisition is sufficient. Our objective was to evaluate the relation between the values of gastric emptying in children obtained by posterior view only and by the geometric mean of conjugate anterior and posterior views. METHODS: The gastric residual of a standard meal was calculated in 81 children of different ages. The calculation of the gastric residual was performed with different methods, posterior only and geometric mean of anterior and posterior acquisitions. The variation between these 2 methods was evaluated in different age groups and different body weights. RESULTS: There was a high correlation (r = 0.942) between the values using posterior as compared with geometric mean for all of the patients. For children younger than 8 years and weighing <30 kg, there was no significant difference between the 2 methods for either liquid or solid meals (P = 0.89 and P = 0.11 for age; P = 0.95 and P = 0.80 for weight). For children older than 8 years and weighing >30 kg, there was no significant difference between the 2 methods for liquids (P = 0.57 for age; P = 0.69 for weight), but there was a significant difference with solids (P < 0.0001 for both age and weight). CONCLUSIONS: In children younger than 8 years and weighing <30 kg, acquisition of a single posterior image is sufficient for calculating gastric emptying at 1 hour postingestion for either liquid or solid meals. In children older than 8 years and weighing >30 kg, acquisition of both anterior and posterior images with geometric mean calculation is recommended when a solid meal is used. If a liquid meal is used in patients older than 8 years, the posterior only may be adequate.

Pediatric Bone Scanning: Clinical Indication of (18)F NaF PET/CT.

Skeletal imaging of children with fluorine-18 ((18)F) NaF harnesses the superior imaging characteristics of positron emission tomography (PET) and the improved biodistribution of the fluoride tracer compared with standard nuclear techniques, resulting in excellent quality images. Bone malignancy in children is less common than in adults, and the evaluation of benign skeletal disorders represents a larger fraction of indications in the pediatric versus adult population. (18)F NaF PET imaging has been successfully applied to various benign disorders, particularly trauma and sports medicine applications.

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.

Skeletal scintigraphy with 18F-NaF PET for the evaluation of bone pain in children.

OBJECTIVE: Although not commonly used in current clinical practice, the PET agent (18)F-NaF provides an excellent alternative to the standard tracers used for radionuclide bone scintigraphy. This article illustrates the use and appearance of (18)F-NaF PET and shows examples of its utility in the assessment of bone pain in children. CONCLUSION: Skeletal imaging with (18)F-NaF harnesses both the superior imaging characteristics of PET and the improved biodistribution of the fluoride tracer in comparison with standard nuclear techniques, resulting in excellent-quality images that can effectively be used to investigate the cause of bone pain in children.