Reducing radiation dose from myocardial perfusion imaging in subjects with complex congenital heart disease.

INTRODUCTION: The prevalence of defects and effective radiation dose from various myocardial perfusion imaging (MPI) strategies in congenital heart disease (CHD) is unknown. METHODS: We studied 75 subjects with complex CHD (ages 5 to 80 years) referred for MPI between 2002 and 2015. A rest and exercise or pharmacologic stress MPI was performed using 99mTechnetium sestamibi, 82rubidium or 13N-ammonia, and Sodium iodide SPECT (single-photon emission computed tomography), SPECT/CT or Cadmium zinc telluride (CZT) SPECT or PET (positron emission tomography)/CT scanners. Deidentified images were interpreted semi-quantitatively in three batches: stress only MPI, stress/rest MPI, and stress/rest MPI with taking into account a history of ventricular septal defect repair. Effective radiation dose was estimated for stress/rest MPI and predicted for 1-day stress-first (normal stress scans), and for 2-day stress/rest MPI (abnormal stress scans). RESULTS: The median age was 18.6 years. The most common type of CHD was transposition of the great arteries (63%). Rest/stress MPI was abnormal in 43% of subjects and 25% of the abnormal scans demonstrated reversible defects. Of the subjects with abnormal MPI, 33% had significant underlying anatomic coronary artery obstruction. Estimated mean effective radiation dose ranged from 2.1 ± 0.6 mSv for 13N-ammonia PET/CT to 12.5 ± 0.9 mSv for SPECT/CT. Predicted effective radiation dose was significantly lower for stress-first MPI and for 2-day stress/rest protocols. CONCLUSIONS: Due to the relatively high prevalence of abnormal stress MPI, tailored protocols with a stress-first MPI as well as the use of 2-day protocols and advanced imaging technologies including CZT SPECT, novel image reconstruction software, and PET MPI could substantially reduce radiation dose in complex CHD.

Celebrating eighty years of radionuclide therapy and the work of Saul Hertz.

March 2021 will mark the eightieth anniversary of targeted radionuclide therapy, recognizing the first use of radioactive iodine to treat thyroid disease by Dr. Saul Hertz on March 31, 1941. The breakthrough of Dr. Hertz and collaborator physicist Arthur Roberts was made possible by rapid developments in the fields of physics and medicine in the early twentieth century. Although diseases of the thyroid gland had been described for centuries, the role of iodine in thyroid physiology had been elucidated only in the prior few decades. After the discovery of radioactivity by Henri Becquerel in 1897, rapid advancements in the field, including artificial production of radioactive isotopes, were made in the subsequent decades. Finally, the diagnostic and therapeutic use of radioactive iodine was based on the tracer principal that was developed by George de Hevesy. In the context of these advancements, Hertz was able to conceive the potential of using of radioactive iodine to treat thyroid diseases. Working with Dr. Roberts, he obtained the experimental data and implemented it in the clinical setting. Radioiodine therapy continues to be a mainstay of therapy for hyperthyroidism and thyroid cancer. However, Hertz struggled to gain recognition for his accomplishments and to continue his work and, with his early death in 1950, his contributions have often been overlooked until recently. The work of Hertz and others provided a foundation for the introduction of other radionuclide therapies and for the development of the concept of theranostics.

Chronic Acalculous Cholecystitis in Children With Biliary Symptoms: Usefulness of Hepatocholescintigraphy.

OBJECTIVES: Chronic acalculous cholecystitis (CAC) increasingly is being diagnosed as a cause of recurring biliary symptoms in children, but its clinical diagnosis remains challenging. The primary objective was to evaluate the utility of hepatocholescintigraphy in pediatric patients with suspected CAC. A secondary objective was to describe their clinical follow-up after diagnosis. METHODS: Medical records of patients (aged 9-20 years) who underwent hepatocholescintigraphy from February 2008 to January 2012 were reviewed. Patients with gallstones, and with ≤1 year of clinical follow-up, and studies without gallbladder (GB) stimulation were excluded. GB ejection fraction (GBEF) of <35% after sincalide or fatty meal (Lipomul) stimulation were considered abnormal. Diagnosis of CAC was based on histopathology after cholecystectomy. Patients with negative GB pathology, or complete resolution of symptoms without surgery, or alternative diagnoses for persistent symptoms were considered to not have CAC. RESULTS: Eighty-three patients formed the study group (median age 14.9 years), of which 81.9% were girls. Median duration of symptoms and clinical follow-up were 6 months and 2.9 years, respectively. Fifty-two patients had at least 1 study with sincalide and 36 patients had at least 1 study with Lipomul. Initial cholescintigraphy was 95.0% sensitive and 73.0% specific in diagnosing CAC, with a negative predictive value of 97.9%. Of the 31 patients with abnormal GBEF, 22 underwent cholecystectomy with improvement in pain in 72.7%, whereas all of the 9 without surgery improved. CONCLUSIONS: Hepatocholescintigraphy is useful for excluding CAC, although the clinical implications of an abnormal GBEF need to be further defined.

Esophageal transit scintigraphy in children: a user's guide and pictorial review.

Technical and clinical aspects of esophageal transit scintigraphy in pediatric patients are reviewed via several illustrative cases that highlight its utility in evaluating primary and secondary esophageal motility disorders.

Pretransplant functional imaging and outcome in pediatric patients with relapsed/refractory Hodgkin lymphoma undergoing autologous transplantation.

BACKGROUND: Pretransplant functional imaging (FI), particularly a negative positron emission tomography (PET), is a strong predictor of outcome in adults with relapsed or refractory Hodgkin lymphoma (HL), but data in pediatrics are limited. METHODS: The medical records of 49 consecutive pediatric patients, who received autologous transplant at a single institution, were retrospectively analyzed. All patients had either gallium or PET scan before transplant and were conditioned with carmustine, etoposide, cytarabine, and melphalan (BEAM). Deauville scores were retrospectively assigned for patients with PET (score ≥ 4 positive). RESULTS: Of the 49 patients (median age, 16.2 years), 41 (84%) were pretransplant FI negative and eight (16%) were pretransplant FI positive, after first- to fourth-line salvage therapy, and a median of two salvage cycles. Eighteen patients (37%) received posttransplant radiation. At a median follow up of 46 months, 45 patients (92%) were alive and disease free, and there were three nonrelapse deaths and only one relapse death (Deauville score of 5). The 4-year progression-free survival (PFS) for the entire cohort was 92% (95% confidence interval [CI]: 78-97), and PFS based on pretransplant disease status was 95% (95% CI: 82-99%) in the negative FI group versus 75% (95% CI: 31-93) if positive FI (P = 0.057). CONCLUSION: Our analysis revealed outstanding outcomes for children and adolescents with relapsed/refractory HL. There were too few relapses to identify the predictive value of pretransplant metabolic status, but pediatric patients with relapsed/refractory HL and a negative pretransplant FI had excellent survival.

Evaluation of the utility of 99m Tc-MDP bone scintigraphy versus MIBG scintigraphy and cross-sectional imaging for staging patients with neuroblastoma.

PURPOSE: Accurate staging of neuroblastoma requires multiple imaging examinations. The purpose of this study was to determine the relative contribution of 99m Tc-methylene diphosphonate (MDP) bone scintigraphy (bone scan) versus metaiodobenzylguanidine scintigraphy (MIBG scan) for accurate staging of neuroblastoma. METHODS: A medical record search by the identified patients with neuroblastoma from 1993 to 2012 who underwent both MIBG and bone scan for disease staging. Cross-sectional imaging was used to corroborate the scintigraphy results. Clinical records were used to correlate imaging findings with clinical staging and patient management. RESULTS: One hundred thirty-two patients underwent both MIBG and bone scan for diagnosis. All stage 1 (n = 12), 2 (n = 8), and 4S (n = 4) patients had a normal bone scan with no skeletal MIBG uptake. Six of 30 stage 3 patients had false (+) bone scans. In the 78 stage 4 patients, 58/78 (74%) were both skeletal MIBG(+)/bone scan (+). In 56 of the 58 cases, skeletal involvement detected with MIBG was equal to or greater than that detected by bone scan. Only 3/78 had (-) skeletal MIBG uptake and (+) bone scans; all 3 had other sites of metastatic disease. Five of 78 had (+) skeletal MIBG with a (-) bone scan, while 12/78 had no skeletal involvement by either MIBG or bone scan. In no case did a positive bone scan alone determine a stage 4 designation. CONCLUSION: In the staging of neuroblastoma, 99m Tc-MDP bone scintigraphy does not identify unique sites of disease that affect disease stage or clinical management, and in the majority of cases bone scans can be omitted from the routine neuroblastoma staging algorithm.

Estimation of Split Renal Function With 99mTc-DMSA SPECT: Comparison Between 3D Volumetric Assessment and 2D Coronal Projection Imaging.

OBJECTIVE: Split renal function (SRF) can be estimated with 99mTc-labeled dimercaptosuccinic acid (DMSA) SPECT cortical renal scintigraphy on either 2D projected images or 3D images. The purpose of this study was to determine whether there is a significant difference between SRF values calculated with the 2D method and those calculated with the 3D method. MATERIALS AND METHODS: This retrospective study was performed with 99mTc-DMSA SPECT images of 316 patients (age range, 1-26 years). All images were reconstructed by filtered back projection. An automated computational method was developed to estimate SRF using both 2D projection images and direct 3D images. A paired t test was used to evaluate the difference between SRFs determined with the two methods and the association between the magnitude of the differences and kidney size, patient age, and SRF. RESULTS: There was strong correlation between SRFs estimated with the 2D and 3D methods (r = 0.94, p < 0.001). There was small significant difference (0.14% ± 0.86%, p = 0.003) in SRFs obtained with the two methods. The difference was clinically negligible and independent of renal length (p = 0.698), volume (p = 0.297), and patient age (p = 0.768) but was associated with SRF (p = 0.018). CONCLUSION: For determination of split renal function, 99mTc-DMSA SPECT renal scintigraphy 2D coronal projection images perform as well as and are simpler to analyze than 3D images.

Pediatric Graves' disease: decisions regarding therapy.

PURPOSE OF REVIEW: Graves' disease is the most common cause of hyperthyroidism in the pediatric population. It occurs more often in adolescence and in girls; however, prepubertal children tend to have more severe disease, require longer medical therapy, and have a lower rate of remission as compared with pubertal children. The choice of which of the three therapeutic options to use (medical therapy, radioactive iodine ablation, or surgery) must be individualized. This update will focus on the current diagnostic and treatment modalities available, as well as address the controversy that exists with regards to permanent therapy. RECENT FINDINGS: The diagnosis of Graves' disease is often made clinically. With the development of second-generation and third-generation thyroid-stimulating hormone receptor antibody assays, it can be more reliably confirmed. An improved understanding of the underlying autoimmune process and genetics is underway; however, remission rates in children and adolescents remain low. Because of its ease of administration and long-term follow-up, there is a trend towards permanent therapy with radioactive iodine ablation when remission cannot be achieved with medical therapy. SUMMARY: New genes and susceptibility loci have been identified with the hope of better understanding the refractory nature of Graves' disease. Despite the low rates of remission, permanent therapy with radioactive iodine remains a good option.

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.

Management of Primary and Secondary Lymphedema: Analysis of 225 Referrals to a Center.

BACKGROUND: Lymphedema is the chronic, progressive enlargement of tissue due to inadequate lymphatic function. Although lymphedema is a specific condition, patients with a large extremity are often labeled as having "lymphedema," regardless of the underlying cause. The purpose of this study was to characterize referrals to a center to determine if lymphedema should be managed by specialists. METHODS: Patients treated in our Lymphedema Program between 2009 and 2013 were reviewed. Diagnosis was determined based on history, physical examination, photographs, and imaging studies. Lymphedema type (primary or secondary), location of swelling, patient age, sex, and previous management were documented. The accuracy of referral diagnosis and the geographic origin of the patients also were analyzed. RESULTS: Two hundred twenty-five patients were referred with a diagnosis of "lymphedema"; 71% were women and 29% were children. Lymphedema was confirmed in 75% of the cohort: primary (49%) and secondary (51%). Twenty-five percent of patients labeled with "lymphedema" had another condition. Before referral 34% of patients with lymphedema received tests that are nondiagnostic for the disease, and 8% were given a diuretic which does not improve the condition. One third of patients resided outside our local referral area. The average time between onset of lymphedema and referral to our Lymphedema Program was 7.7 years (range, 1-59 years). CONCLUSIONS: Patients presenting to a center with "lymphedema" often have another condition, and may be suboptimally managed before their referral. Patients with suspected lymphedema should be referred to specialists focused on this disease.

Detection of pars injury by SPECT in patients younger than age 10 with low back pain.

BACKGROUND: Evaluation of extension-based low back pain in young athletes with suspected pars injury may include a referral for skeletal single photon emission computed tomography (SPECT). However, the diagnostic yield of this technique in children with low back pain before the age of 10 years remains uncertain. We examined a series of consecutive SPECT scans to address this question. MATERIALS AND METHODS: A retrospective review of department databases revealed 107 consecutive skeletal Tc-99m MDP SPECT scans performed between January 1, 2007 and December 31, 2009 in children less than 10 years of age. Of these, 72 studies were performed for a referral diagnosis of back pain. There were 43 girls (44 studies) and 28 boys (28 studies). The mean age was 7.2 years (range, 1.9 to 9.9 y). All SPECT scans were reviewed and positive findings documented. In addition, all available anatomic imaging, imaging reports (computed tomography, magnetic resonance, and x-ray) and clinical notes were reviewed, and results were compared with those of SPECT studies. RESULTS: Of the 72 SPECT studies, 35 (49%) identified a focal area in the spine of abnormal increased uptake, with 17 in the region of the pars interarticularis. With additional imaging, 1 case was demonstrated not to be a pars injury (computed tomography showed a transverse process fracture) and 2 patients with negative SPECT scans were shown to have pars injuries that SPECT scan had not detected, for a total of 18 pars injuries (25%) in this cohort. Reported participation in gymnastics or football was related to pars injury (odds ratio 4.3, P=0.04). CONCLUSIONS: Pars injury was found in 25% of children referred for SPECT scan with back pain below 10 years of age. SPECT scan was highly sensitive for this injury as well as in identifying other potential sites of pathology, and should be considered in the workup of persistent low back pain in young children. LEVEL OF EVIDENCE: Level II, diagnostic study.

Summary: Appropriate Use Criteria for Lymphoscintigraphy in Sentinel Node Mapping and Lymphedema/Lipedema.

Expert representatives from 11 professional societies, as part of an autonomous work group, researched and developed appropriate use criteria (AUC) for lymphoscintigraphy in sentinel lymph node mapping and lymphedema. The complete findings and discussions of the work group, including example clinical scenarios, were published on October 8, 2022, and are available at https://www.snmmi.org/ClinicalPractice/content.aspx?ItemNumber=42021 The complete AUC document includes clinical scenarios for scintigraphy in patients with breast, cutaneous, and other cancers, as well as for mapping lymphatic flow in lymphedema. Pediatric considerations are addressed. These AUC are intended to assist health care practitioners considering lymphoscintigraphy. Presented here is a brief overview of the AUC, including the rationale and methodology behind development of the document. For detailed findings of the work group, the reader should refer to the complete AUC document online.

Outcomes of ATA Low-Risk Pediatric Thyroid Cancer Patients Not Treated With Radioactive Iodine Therapy.

CONTEXT: The American Thyroid Association (ATA) Pediatric Guidelines recommend patients not receive radioactive iodine therapy (RAIT) for differentiated thyroid cancer (DTC) confined to the thyroid. Since publication, there is ongoing concern whether withholding RAIT will result in a lower rate of remission. OBJECTIVE: This study explores whether ATA low-risk patients treated with and without RAIT achieved similar remission rates. METHODS: Medical records of patients <19 years old diagnosed with DTC and treated with total thyroidectomy between 2010 and 2020 were reviewed. Multivariate logistic regression was performed to evaluate factors influencing RAIT administration and remission rate. RESULTS: Ninety-five patients with ATA low-risk DTC were analyzed: 53% (50/95) and 47% (45/95) were treated with and without RAIT, respectively. RAIT was used to treat 82% of patients before 2015 compared with 33% of patients after 2015 (P < .01). No significant difference in 1-year remission rate was found between patients treated with and without RAIT, 70% (35/50) vs 69% (31/45), respectively. With longer surveillance, remission rates increased to 82% and 76% for patients treated with and without RAIT, respectively. Median follow-up was 5.8 years (IQR 4.3-7.9, range 0.9-10.9) and 3.6 years (IQR 2.7-6.6; range 0.9-9.3) for both cohorts. No risk factors for persistent or indeterminate disease status were found, including RAIT administration, N1a disease, and surgery after 2015. CONCLUSION: Withholding RAIT for pediatric patients with ATA low-risk DTC avoids exposure to radiation and does not have a negative impact on remission rates. Dynamic risk stratification at 1-year after initial treatment is a suitable time point to assess the impact of withholding RAIT for these patients.

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.

Deferasirox pharmacokinetics in patients with adequate versus inadequate response.

Tens of thousands of transfusion-dependent (eg, thalassemia) patients worldwide suffer from chronic iron overload and its potentially fatal complications. The oral iron chelator deferasirox has become commercially available in many countries since 2006. Although this alternative to parenteral deferoxamine has been a major advance for patients with transfusional hemosiderosis, a proportion of patients have suboptimal response to the maximum approved doses (30 mg/kg per day), and do not achieve negative iron balance. We performed a prospective study of oral deferasirox pharmacokinetics (PK), comparing 10 transfused patients with inadequate deferasirox response (rising ferritin trend or rising liver iron on deferasirox doses > 30 mg/kg per day) with control transfusion-dependent patients (n = 5) with adequate response. Subjects were admitted for 4 assessments: deferoxamine infusion and urinary iron measurement to assess readily chelatable iron; quantitative hepatobiliary scintigraphy to assess hepatic uptake and excretion of chelate; a 24-hour deferasirox PK study following a single 35-mg/kg dose of oral deferasirox; and pharmacogenomic analysis. Patients with inadequate response to deferasirox had significantly lower systemic drug exposure compared with control patients (P < .00001). Cmax, volume of distribution/bioavailability (Vd/F), and elimination half-life (t(1/2)) were not different between the groups, suggesting bioavailability as the likely discriminant. Effective dosing regimens for inadequately responding patients to deferasirox must be determined. This trial has been registered at http://www.clinicaltrials.gov under identifier NCT00749515.

Skeletal trauma in child abuse: detection with 18F-NaF PET.

PURPOSE: To evaluate the sensitivity of fluorine 18-labeled sodium fluoride ((18)F-NaF) positron emission tomography (PET) for assessment of skeletal trauma in pediatric patients suspected of having been abused and to compare the diagnostic performance of this examination with that of high-detail skeletal survey. MATERIALS AND METHODS: The institutional review board approved this retrospective study and determined that it was in accordance with regulations of HIPAA privacy rule 45, Code of Federal Regulations parts 160 and 164, and that the criteria for waived patient authorization were met. The baseline skeletal survey and PET images obtained in 22 patients younger than 2 years between September 2007 and January 2009 were reviewed. Fourteen patients also underwent follow-up skeletal survey. The PET images were interpreted by two pediatric nuclear medicine physicians. The initially obtained skeletal survey images were interpreted blindly by a pediatric radiologist. A second pediatric radiologist interpreted the follow-up skeletal survey images in conjunction with the baseline survey images and rendered a final interpretation for the 14 patients in whom both baseline and follow-up skeletal survey data were available, which served as the reference standard. RESULTS: A total of 156 fractures were detected at baseline skeletal survey, and 200 fractures were detected at PET. Compared with the reference standard (findings in the 14 patients who underwent baseline and follow-up skeletal survey), PET had sensitivities of 85% for the detection of all fractures, 92% for the detection of thoracic fractures (ribs, sternum, clavicle, and scapula), 93% for the detection of posterior rib fractures, and 67% for the detection of classic metaphyseal lesions (CMLs), defined as a series of microfractures across the metaphysis. Compared with the reference standard, baseline skeletal survey had sensitivities of 72% for the detection of all fractures, 68% for the detection of thoracic fractures, 73% for the detection of posterior rib fractures, and 80% for the detection of CMLs. CONCLUSION: (18)F-NaF PET had greater sensitivity in the overall detection of fractures related to child abuse than did baseline skeletal survey. (18)F-NaF PET was superior in the detection of rib fractures in particular. Thus, (18)F-NaF PET is an attractive choice for evaluation of suspected child abuse, an application in which high sensitivity is desirable. Because of the lower sensitivity of PET in the detection of CMLs, a characteristic fracture in child abuse, initial radiographic evaluation remains necessary.

Seasonal variation in the effect of constant ambient temperature of 24 degrees C in reducing FDG uptake by brown adipose tissue in children.

PURPOSE: It has been shown that warming patients prior to and during (18)F-FDG uptake by controlling the room temperature can decrease uptake by brown adipose tissue (BAT). The aim of this study is to determine if this effect is subject to seasonal variation. METHODS: A retrospective review was conducted of all patients referred for whole-body (18)F-FDG PET between December 2006 and December 2008. After December 2007, all patients were kept in the PET injection room at a constant 24 degrees C for 30 min before and until 1 h following FDG administration. Patients over 22 years of age and those who received pre-medication known to reduce FDG uptake by BAT were excluded. One hundred and three patients were warmed to 24 degrees C prior to scanning. The number of patients showing uptake by BAT in this group was compared to a control group of 99 patients who underwent PET prior to December 2007 when the injection room temperature was 21 degrees C. RESULTS: Uptake by BAT occurred in 9% of studies performed after patient warming (24 degrees C), compared to 27% of studies performed on the control group (21 degrees C) (p < 0.00001). The effect of warming on decreasing FDG accumulation in BAT was statistically significant in the winter (p < 0.005) and summer (p < 0.001). However, in the spring and autumn, though the effect of warming on decreasing FDG accumulation in BAT was evident, it was not statistically significant (p > 0.05). CONCLUSION: Maintaining room temperature at a constant 24 degrees C for 30 min prior to and 1 h after IV tracer administration significantly decreases FDG uptake by BAT in children. This effect is greatest in the summer and winter.

Skeletal scintigraphy in pediatric sports medicine.

OBJECTIVE: Athletes can have pain derived from fractures or alternate pathology. Skeletal scintigraphy may detect abnormalities before anatomic imaging and provides a practical tool for whole-body imaging. However, study interpretation in children can be challenging. This pictorial essay describes a technique for pediatric skeletal scintigraphy and reviews findings commonly encountered in athletes. CONCLUSION: Skeletal scintigraphy complements anatomic findings in pediatric athletes. Familiarity with imaging technique and study interpretation can improve diagnosis.

Constant ambient temperature of 24 degrees C significantly reduces FDG uptake by brown adipose tissue in children scanned during the winter.

PURPOSE: The aim of this study was to determine if warming patients prior to and during (18)F-FDG uptake by controlling the room temperature could decrease uptake by brown adipose tissue (BAT). METHODS: A group of 40 children underwent (18)F-FDG PET after being kept in the injection room at a constant temperature of 24 degrees C for half an hour before and 1 hour after intravenous tracer administration. The rate of uptake by BAT in this group was compared to the uptake in a control group of 45 patients who underwent PET when the injection room temperature was 21 degrees C. RESULTS: Uptake by BAT occurred in 5% of studies in the temperature-controlled room compared to 31% of studies performed when the injection room temperature was 21 degrees C (p<0.002). CONCLUSION: Maintaining room temperature at a constant 24 degrees C, half an hour prior to and during the period of FDG uptake significantly decreases accumulation of FDG in BAT in children.