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.

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.

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.

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.

Implementation of a Flipped Classroom for Nuclear Medicine Physician CME

INTRODUCTION

Increasingly, emerging technologies are expanding instructional possibilities, with new methods being adopted to improve knowledge acquisition and retention. Within medical education, many new techniques have been employed in the undergraduate setting, with less utilization thus far in the continuing medical education (CME) sphere. This paper discusses the use of a new method for CME-the "flipped classroom," widely used in undergraduate medical education. This method engages learners by providing content before the live ("in class") session that aids in preparation and fosters in-class engagement.

METHODS

A flipped classroom method was employed using an online image-rich case-based module and quiz prior to a live CME session at a national nuclear medicine meeting. The preparatory material provided a springboard for in-depth discussion at the live session-a case-based activity utilizing audience response technology. Study participants completed a survey regarding their initial experience with this new instructional method. In addition, focus group interviews were conducted with session attendees who had or had not completed the presession material; transcripts were qualitatively analyzed.

RESULTS

Quantitative survey data (completed by two-thirds of the session attendees) suggested that the flipped method was highly valuable and met attendee educational objectives. Analysis of focus group data yielded six themes broadly related to two categories-benefits of the flipped method for CME and programmatic considerations for successfully implementing the flipped method in CME.

DISCUSSION

Data from this study have proven encouraging and support further investigations around the incorporation of this innovative teaching method into CME for nuclear imaging specialists.

Saul Hertz, MD, and the birth of radionuclide therapy

The year, 2016, marked the 75th anniversary of Dr. Saul Hertz first using radioiodine to treat a patient with thyroid disease. In November of 1936, a luncheon was held of the faculty of Harvard Medical School where Karl Compton, PhD, president of the Massachusetts Institute of Technology was invited to give a presentation entitled "What Physics Can Do for Biology and Medicine." Saul Hertz who attended the luncheon spontaneously asked the very pertinent question that perhaps changed the course of treatment of thyroid disease, "Could iodine be made radioactive artificially?" We review the events leading up to the asking of this question, the preclinical investigations by Dr. Hertz and his colleague Arthur Roberts prior to the treatment of the first patient and what occurred in the years following this landmark event. This commentary seeks to set the record straight to the sequence of events leading to the first radioiodine therapy, so that those involved can be recognized with due credit.

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.

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.

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.

¹⁸F-fluoride PET and PET/CT in children and young adults

18F-fluoride PET/CT has been used for a wide variety of indications in children and young adults. Nearly all pediatric 18F-fluoride PET/CTs are performed to evaluate benign conditions. The most common indication is the evaluation of back pain in a wide variety of circumstances, including patients with sports injuries, scoliosis, trauma, and back pain after surgery. The high image quality of 18F-fluoride PET/CT can make it particularly useful for evaluating benign skeletal lesions such as osteoid osteoma and Langerhans cell histiocytosis. Quantitative assessment of bone turnover with 18F-fluoride PET/CT may make it useful for assessing the skeleton in patients with metabolic bone diseases, eating disorders, and avascular necrosis. There is little pediatric experience using 18F-fluoride PET/CT for evaluation of skeletal or soft tissue disease in childhood cancers.

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.

Economic and radiation costs of initial imaging approaches after a child's first febrile urinary tract infection

BACKGROUND. The traditional initial imaging approach following pediatric urinary tract infection is the "bottom-up" approach (cystogram and renal ultrasound). Recently, the "top-down" approach (nuclear renal scan followed by cystogram for abnormal scans only) has gained increasing attention. The relative cost and radiation doses of these are unknown METHODS. The authors used a decision model to evaluate these imaging approaches. Cost and effective radiation dose estimates, including sensitivity analyses, were based on one-time imaging only. RESULTS. Comparing hypothetical cohorts of 100 000 children, the top-down imaging approach cost $82.9 million versus $59.2 million for the bottom-up approach. Per-capita effective radiation dose was 0.72 mSv for top-down compared with 0.06 mSv for bottom-up. CONCLUSIONS. Routine use of nuclear renal scans in children following initial urinary tract infection diagnosis would result in increased imaging costs and radiation doses as compared to initial cystogram and ultrasound. Further data are required to clarify the long-term clinical implications of this increase.

Costs and consequences of universal sibling screening for vesicoureteral reflux: decision analysis

OBJECTIVE

Our objective was to evaluate screening for vesicoureteral reflux (VUR) among siblings of patients with VUR, in terms of cost, radiation exposure, and number of febrile urinary tract infections (fUTIs) averted.

METHODS

We constructed a Markov model to evaluate 2 competing management options, that is, universal screening (cystographic evaluation of all siblings without symptoms) and usual care (cystographic evaluation of siblings only after fUTIs). Published data were used to inform all model inputs. Costs were estimated by using a societal perspective.

RESULTS

Universal screening yielded 2980 fUTIs, whereas usual care yielded 6330. Therefore, universal screening for VUR in a cohort of 100,000 siblings 1 year of age without symptoms resulted in the prevention of 1 initial fUTI per 3360 siblings, at an excess cost of $55,600 per averted fUTI, in comparison with usual care. These estimates were heavily dependent on screening age and the effectiveness of antibiotic prophylaxis; prevention of a single fUTI would require screening of 166 siblings 5 years of age and 694 siblings 10 years of age. Similarly, if prophylaxis was ineffective in preventing fUTIs, then up to 10,000 siblings would need to be screened for prevention of a single fUTI.

CONCLUSIONS

Prevention of a single fUTI would require screening of 30 to 430 siblings 1 year of age without symptoms, at an estimated excess cost of $56,000 to $820,000 per averted fUTI. These estimates are heavily dependent on screening age and the effectiveness of antibiotic prophylaxis.

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 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.

The value of SPECT in the detection of stress injury to the pars interarticularis in patients with low back pain

The medical cost associated with back pain in the United States is considerable and growing. Although the differential diagnosis of back pain is broad, epidemiological studies suggest a correlation between adult and adolescent complaints. Injury of the pars interarticularis is one of the most common identifiable causes of ongoing low back pain in adolescent athletes. It constitutes a spectrum of disease ranging from bone stress to spondylolysis and spondylolisthesis. Bone stress may be the earliest sign of disease. Repetitive bone stress causes bone remodeling and may result in spondylolysis, a non-displaced fracture of the pars interarticularis. A fracture of the pars interarticularis may ultimately become unstable leading to spondylolisthesis. Results in the literature support the use of bone scintigraphy to diagnose bone stress in patients with suspected spondylolysis. Single photon emission computed tomography (SPECT) provides more contrast than planar bone scintigraphy, increases the sensitivity and improves anatomic localization of skeletal lesions without exposing the patient to additional radiation. It also provides an opportunity for better correlation with other imaging modalities, when necessary. As such, the addition of SPECT to standard planar bone scintigraphy can result in a more accurate diagnosis and a better chance for efficient patient care. It is our expectation that by improving our ability to correctly diagnose bone stress in patients with suspected injury of the posterior elements, the long-term cost of managing this condition will be lowered.

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.

Mucoepidermoid carcinoma of bronchus in a pediatric patient: (18)F-FDG PET findings

In children, primary neoplasms of the tracheobronchial tree and lungs are rare; most are malignant. Of the primary malignant pulmonary neoplasms arising in childhood, mucoepidermoid carcinoma accounts for approximately 10%. Due to its well-confined local growth within the airway, mucoepidermoid carcinoma commonly produces respiratory symptoms from progressive tracheal or bronchial obstruction. Mucoepidermoid tumor has minimal metastatic potential in children, and local resection alone is the current treatment of choice. Early detection, diagnosis, and surgical resection of mucoepidermoid tumor are especially important in pediatric patients since the bulk of the remaining pulmonary parenchyma can be preserved, thereby decreasing the thoracic deformity and pulmonary functional morbidity. Radiographic and CT imaging findings of bronchial mucoepidermoid carcinoma in children have been described in several case reports. However, to the best of our knowledge, imaging findings of 2-((18)F)-fluoro-2-deoxy-D: -glucose positron emission tomography ((18)F-FDG PET) of mucoepidermoid carcinoma of the bronchus in pediatric patients have not been well established. We report a mucoepidermoid carcinoma arising from the right upper lobe bronchus in a 15-year-old girl with an emphasis on the (18)F-FDG PET findings.

Surficial Deposits at Gusev Crater Along Spirit Rover Traverses

The Mars Exploration Rover Spirit has traversed a fairly flat, rock-strewn terrain whose surface is shaped primarily by impact events, although some of the landscape has been altered by eolian processes. Impacts ejected basaltic rocks that probably were part of locally formed lava flows from at least 10 meters depth. Some rocks have been textured and/or partially buried by windblown sediments less than 2 millimeters in diameter that concentrate within shallow, partially filled, circular impact depressions referred to as hollows. The terrain traversed during the 90-sol (martian solar day) nominal mission shows no evidence for an ancient lake in Gusev crater.

Low-renin hypertension, altered sodium homeostasis, and an alpha-adducin polymorphism

Defining the genetic basis of common forms of human essential hypertension is most informative when correlated with physiological mechanisms that underlie blood pressure regulation. A polymorphism of the alpha-adducin gene as been associated with elevated blood pressure in the rat, but previous studies of the 460Trp polymorphism of the human alpha-adducin gene have not clearly identified an association with hypertension. In this study, the frequency of the 460Trp allele was 19% and 9 of 279 subjects (3.2%) were homozygous for the 460Trp allele. The systolic blood pressure response to changes in dietary sodium was significantly greater in subjects homozygous for the 460Trp allele (25 +/- 4 mm Hg) compared with subjects heterozygous for 460Trp (12 +/- 2 mm Hg) or homozygous for the 460Gly allele (14 +/- 1 mm Hg). Intracellular erythrocyte sodium content, sodium-lithium countertransport, and renal fractional excretion of sodium were significantly decreased in subjects homozygous for the 460Trp polymorphism (P<0.05). There was a significant association between homozygosity for the 460Trp allele and low-renin hypertension. Subjects heterozygous for the 460Trp allele did not have increased salt-sensitivity or an increased frequency of low-renin hypertension. Therefore, this study demonstrates a common genetic basis for altered cellular sodium homeostasis, impaired renal sodium handling, and salt-sensitivity of systolic blood pressure in individuals homozygous for the 460Trp polymorphism of the alpha-adducin gene. Homozygosity for this alpha-adducin allele may be an important determinant for approximately 10% of individuals with low-renin hypertension.

High risk of infertility and long term gonadal damage in males treated with high dose cyclophosphamide for sarcoma during childhood

BACKGROUND

Therapy with alkylating agents, such as cyclophosphamide, can be associated with irreversible gonadal toxicity in male survivors of adult cancer. To the authors's knowledge the effect of high dose therapy with cyclophosphamide during childhood on adult testicular reproductive and endocrine function has not been established.

METHODS

Gonadal function was studied in 17 adult male survivors of childhood sarcomas treated with high dose pulse cyclophosphamide therapy as part of a VAC (vincristine, actinomycin, and cyclophosphamide) or Adria-VAC (doxorubicin, vincristine, actinomycin, and cyclophosphamide) chemotherapy regimen. Patients answered a questionnaire concerning sexual functioning and underwent a comprehensive physical examination, semen analysis, and hormonal evaluation.

RESULTS

Of the 17 males who underwent semen analysis, 10 (58.8%) had azoospermia, 5 (29.4%) had oligospermia, and only 2 (11.8%) were found to have a normal sperm count. All patients treated prior to the onset of puberty had an abnormal semen analysis. The 2 patients with normal sperm counts received the lowest doses of cyclophosphamide (< 7.5 g/m(2)). The baseline follicle-stimulating hormone level was elevated in only 10 of 14 patients with abnormal sperm counts (71.4%). Testosterone levels were normal in 15 of 16 patients (93.8%); however, the baseline luteinizing hormone (LH) level was elevated in 6 of 15 patients with normal testosterone levels (40%). Gonadotropin-releasing hormone-stimulated LH levels were > 3 times that of baseline in 13 of /14 patients (92.9%), suggesting some degree of Leydig cell insufficiency.

CONCLUSIONS

The results of the current study show a high risk of gonadal dysfunction in men exposed to cyclophosphamide during childhood as part of a VAC/Adria-VAC chemotherapy regimen. Exposure prior to puberty was not found to be protective, and the risk of infertility appeared to increase with higher doses of therapy. To the authors' knowledge the clinical significance of impaired Leydig cell function beginning at a young age is unknown and merits further study.

Homozygosity for an Alpha-Adducin Polymorphism (460TRP) Is Associated with Salt-Sensitivity and Low-Renin Hypertension in Humans

P133

Single nucleotide polymorphisms of the adducin genes have been associated with the development of elevated blood pressure in the rat. However, previous studies of the 460Trp polymorphism of human alpha-adducin have not clearly identified an association with the development of human hypertension. In this study, 281 hypertensive subjects were subgrouped by the intermediate phenotypes of plasma renin status and sensitivity of systolic blood pressure to dietary sodium. The frequency of the 460Trp allele was 19% and 9 of 281 subjects (3.2%) were homozygous (TT) for the 460Trp allele. The systolic blood pressure response to changes in dietary sodium (>150 meq/d vs. ≤30 meq/d) was significantly (p < 0.05) greater in TT subjects (25 ± 2 mmHg) compared to those heterozygous (GT) for the 460Trp allele (12 ± 2 mmHg) or homozygous (GG) for the 460Gly allele (14 ± 1 mmHg). There was a significant (p < 0.005) association between homozygosity for the 460Trp allele and low-renin hypertension. Six of 67 (9%) low-renin subjects, but only 3 of 214 (1.4%) normal- renin subjects had the TT genotype. Heterozygous (GT) subjects did not have increased salt-sensitivity of systolic blood pressure and did not have an increased frequency of low-renin hypertension. Erythrocyte sodium content was significantly (p < 0.01) less in subjects with the TT genotype (24.5 ± 1.0 mmol/kgHgb) compared to all subjects (33.2 ± 0.4 mmol/kgHgb). Subjects with the TT genotype had a significantly (p < 0.05) lower sodium-lithium countertransport (SLC) (0.16 ± 0.04 mmol/l/h) than other subjects (0.28 ± 0.01 mmol/l/h). However, the mean SLC of all low-renin hypertensive subjects (0.25 ± 0.02 mmol/l/h) was not significantly different than the mean SLC of normal-renin hypertensive subjects (0.26 ± 0.01 mmol/l/h). Thus, a decreased SLC is associated with the TT genotype and is not a characteristic of all individuals with low-renin hypertension. These findings suggest that homozygous expression of the 460Trp polymorphism of the alpha-adducin gene alters sodium handling in humans and may be an important contributor to the development of low-renin hypertension in some individuals.

Genetic models of vasopressin deficiency

Animal models of genetic hormone deficiency are useful as models for physiological studies of hormone deficiency and hormone action. Structure-function studies of the specific underlying gene defect may help in understanding mechanisms regulating gene expression and secretion of the peptide product. Spontaneous genetic models of vasopressin deficiency, such as the Brattleboro rat and human familial diabetes insipidus, have facilitated many studies of vasopressin. However, the Brattleboro rat may not be an ideal model of genetic vasopressin deficiency and therefore could be less useful for studies of the central nervous system or as a background strain for the introduction of new vasopressin gene constructs. The human model is appropriately limited by the constraints of human studies, so that engineered animal models of specific diseases, such as familial neurohypophysial diabetes insipidus, are required. The recent development of a vasopressin-null mouse may provide insights into the various roles of vasopressin in the stress response, cardiovascular regulation and behaviour. Additionally, animals with a complete genetic deficiency of vasopressin can serve as a background strain for introduction of novel vasopressin gene constructs to enable sophisticated studies of the regulation of vasopressin expression and the intracellular processes required for appropriate secretion of vasopressin peptide. As advanced techniques of genetic manipulation become more reliable, conditional expression of vasopressin, regulated by time or body site will permit even more detailed studies in this field.

Two novel mutations of the vasopressin gene associated with familial diabetes insipidus and identification of an asymptomatic carrier infant

Familial diabetes insipidus (FDI) is a syndrome of central vasopressin deficiency that is inherited in an autosomal dominant manner and that typically becomes clinically apparent in the first decade of life. Two novel mutations of the vasopressin gene have been identified in two previously unstudied kindreds with FDI. In each kindred, the inheritance of the FDI phenotype was consistent with an autosomal dominant mode of inheritance. In each proband, the diagnosis of central diabetes insipidus had been confirmed previously with a water deprivation protocol. After extraction of genomic DNA from each individual, the three exons of the vasopressin gene were separately amplified by PCR and directly sequenced using an automated dye termination method. In the proband and two other carriers of one kindred, a heterozygous C to T mutation was identified at nucleotide 1857. This is predicted to produce a serine to phenylalanine substitution at residue 56 of the vasopressin-related neurophysin peptide encoded by the mutated allele. The mutation also abolished an MspI site in the vasopressin sequence, and analysis of genomic DNA from eight members of the kindred (five with FDI) confirmed segregation of the mutation with the FDI phenotype. Another member of the kindred, a 13-month-old infant, also has the heterozygous C to T mutation, but a formal water balance study showed no evidence of diabetes insipidus. In the proband of the other kindred, a heterozygous G to A mutation was identified at nucleotide 1873. This mutation would be predicted to cause a cysteine to tyrosine substitution at residue 61 of the neurophysin encoded by the mutated allele. This heterozygous mutation was confirmed by the presence of an RsaI restriction site in one vasopressin allele in two members of the kindred. Therefore, two novel heterozygous mutations of the vasopressin gene have been identified in FDI kindreds. In one kindred, an asymptomatic carrier infant was identified and will require continued observation to determine whether she will develop clinical diabetes insipidus. The presence of these two novel mutations in a region of the vasopressin gene where other FDI mutations have been reported suggests that the part of the neurophysin peptide encoded by these sequences may be critically important in the appropriate expression of vasopressin.

Modulation of rat rotational behavior by direct gene transfer of constitutively active protein kinase C into nigrostriatal neurons

The modulation of motor behavior by protein kinase C (PKC) signaling pathways in nigrostriatal neurons was examined by using a genetic intervention approach. Herpes simplex virus type 1 (HSV-1) vectors that encode a catalytic domain of rat PKCbetaII (PkcDelta) were developed. PkcDelta exhibited a constitutively active protein kinase activity with a substrate specificity similar to that of rat brain PKC. As demonstrated in cultured sympathetic neurons, PkcDelta caused a long-lasting, activation-dependent increase in neurotransmitter release. In the rat brain, microinjection of HSV-1 vectors that contain the tyrosine hydroxylase promoter targeted expression to dopaminergic nigrostriatal neurons. Expression of pkcDelta in a small percentage of nigrostriatal neurons (approximately 0.1-2%) was sufficient to produce a long-term (>/=1 month) change in apomorphine-induced rotational behavior. Nigrostriatal neurons were the only catecholaminergic neurons that contained PkcDelta, and the amount of rotational behavior was correlated with the number of affected nigrostriatal neurons. The change in apomorphine-induced rotational behavior was blocked by a dopamine receptor antagonist (fluphenazine). D2-like dopamine receptor density was increased in those regions of the striatum innervated by the affected nigrostriatal neurons. Therefore, this strategy enabled the demonstration that a PKC pathway or PKC pathways in nigrostriatal neurons modulate apomorphine-induced rotational behavior, and altered dopaminergic transmission from nigrostriatal neurons appears to be the affected neuronal physiology responsible for the change in rotational behavior.

Long-term persistence of defective HSV-1 vectors in the rat brain is demonstrated by reactivation of vector gene expression

Wild-type HSV-1 is known to persist indefinitely in neurons in the latent state; however, defective HSV-1 vectors, or amplicons, contain only approximately 1% of the HSV-1 genome and persistence of these HSV-1 vectors has not been studied even semiquantitatively in the adult rat brain. Defective HSV-1 vectors contain both an HSV-1 origin of replication and a packaging site, and in the presence of helper virus can undergo DNA replication and packaging into HSV-1 particles. Our prototype defective HSV-1 vector, pHSVlac, uses the HSV-1 immediate-early (IE) promoter to regulate expression of the Escherichia coli lacZ gene. Using cultured neuronal cells, we have previously shown that expression from pHSVlac can be augmented by superinfection with a helper virus. In this study, pHSVlac was delivered into the adult rat striatum or hippocampus, and 2-3 months after gene transfer we utilized superinfection with several replication-incompetent HSV-1 mutants to reactivate expression from pHSVlac in approximately 30% of the number of cells observed at 4 days after gene transfer. Thus, HSV-1 plasmid vectors can persist for at least 2-3 months in at least approximately 30% of the cells which are initially infected.

Racial differences in parathyroid hormone dynamics

Elevations in PTH levels have been reported in black subjects. Such observations have not been consistent, however, and seem paradoxical in view of the known bone-resorptive action of this hormone and the fact that black subjects have a higher bone mineral density and fewer fractures than their white counterparts. In this study, we used dynamic stimulation of the calcium-PTH axis to fully characterize potential racial differences in PTH dynamics. We, therefore, defined the inverse sigmoidal curve that describes the relationship between serum ionized calcium concentration and intact PTH levels in six normal white and six normal black volunteers and determined the four parameters that characterize this relationship. An elevation in any one of these parameters can result in hyperparathyroidism. Black subjects had higher maximal and minimal PTH responses to hypo- and hypercalcemia (mean intact PTH levels of 9.2 +/- 13 and 0.7 +/- 0.1 pmol/L respectively) than white subjects (6.9 +/- 0.6 and 0.3 +/- 0.1 pmol/L, respectively). There were no differences in the set-points or slopes of the curves. Despite the higher baseline and stimulated endogenous PTH levels in black subjects, their baseline and stimulated osteocalcin levels were lower. Our dynamic studies, therefore, document mild hyperparathyroidism in black subjects and suggest mild skeletal resistance to PTH.

Transgenic mouse models of vasopressin expression

Arginine vasopressin is a nine-amino acid neuropeptide hormone important in the regulation of water metabolism. It also may have a role in other physiological functions, such as blood pressure regulation and the response to stress. Whole animal studies have provided a good understanding of vasopressin physiology and regulation of the normal vasopressin gene, and in vitro cell culture studies have demonstrated important features of the intracellular regulation of vasopressin gene expression. Transgenic mice provide useful models for the study of the in vivo regulation of gene expression. Previously reported mouse lines transgenic with vasopressin gene constructs have not expressed the transgene in a tissue distribution similar to that detected for the endogenous mouse vasopressin gene. An 8.2-kb genomic construct of the rat vasopressin gene, including 3 kb each of 5' and 3' flanking sequences, has been used to develop a line of transgenic mice. These animals express the transgene in a tissue-specific manner, demonstrate appropriate osmotic regulation of transgenic vasopressin mRNA, and have normal water metabolism. Animals homozygous for the 8.2-kb transgene have increased basal plasma levels of vasopressin peptide but have no apparent change in basal water metabolism. The findings with this and other previously reported mouse lines transgenic for vasopressin constructs provide a basis for developing future transgenic lines to study the in vivo regulation of the vasopressin gene.

Expression of the rat arginine vasopressin gene in transgenic mice

A line of mice has been developed which are transgenic for an 8.2-kilobase (kb) genomic clone of the rat vasopressin (VP) gene. Using a polymerase chain reaction technique, the rat VP (rVP) transgene was shown to have tissue-specific mRNA expression in the hypothalamus, temporal lobe, parietal cerebral cortex, cerebellum, and posterior pituitary, similar to the tissue distribution of endogenous mouse and rat VP expression. Expression of transgenic rVP mRNA was also found in the lung and pancreas of the transgenic mice, sites of known ectopic expression of VP. Using two methods, Northern blot analysis with species-specific cRNA probes and a quantitative polymerase chain reaction technique, the quantity of rVP transgene mRNA was shown to regulate appropriately in response to an osmotic stimulus. After 72 h of water deprivation, the quantity of transgenic rVP mRNA increased 6.8 +/- 3.0-fold. This was not significantly different than the fold increase in mouse VP mRNA quantity seen in nontransgenic mice (4.8 +/- 1.5) but was significantly different (P < 0.05) than the 1.2 +/- 0.03-fold increase in rat VP mRNA seen in normal rats after water deprivation. In the rat hypothalamus, VP mRNA poly(A) tail length increases with osmotic stimulation, while in the mouse it does not. The poly(A) tail of transgenic rVP mRNA expressed in mouse hypothalamus did not increase in length after osmotic stimulation.(ABSTRACT TRUNCATED AT 250 WORDS)

Interrelationships between the renin-angiotensin-aldosterone and calcium homeostatic systems

Blood pressure is affected by both sodium and calcium intake. To determine if there is an interaction between the regulatory mechanisms for these two cations, eight normal male volunteers received the following 1-h infusions on three different days: 1) angiotensin II (AII), 2) the synthetic 1-34 amino terminal fragment of human PTH [hPTH(1-34)], and 3) AII and hPTH(1-34) together. Blood samples were obtained at t = 0 and every 20 min during each infusion and urine was collected for 3 h both before and after the start of each infusion. Infusion of AII produced an increase in intact PTH from 18 +/- 2 to 31 +/- 4 ng/L (P < 0.05), most likely in response to a small decrease in serum ionized calcium (1.25 +/- 0.01 to 1.23 +/- 0.01 mmol/L, P < 0.05). Urinary excretion of calcium was unchanged. Infusion of hPTH(1-34) at 200 U/h increased N-terminal PTH levels (18 +/- 3 to 268 +/- 42 ng/L, P < 0.05), decreased tubular reabsorption of phosphate (0.92 +/- 0.03 to 0.82 +/- 0.11, P < 0.05), and increased urinary cAMP (0.18 +/- 0.02 to 0.53 +/- 0.05 nmol/L of glomerular filtrate, P = 0.0001). hPTH(1-34) infusion suppressed endogenous intact PTH (18 +/- 3 to 14 +/- 2 ng/L, P < 0.005) and increased PRA from 0.14 +/- 0.02 to 0.32 +/- 0.05 ng/(L.s) (P < 0.05) without a change in serum ionized calcium which suggests direct effects of hPTH(1-34) on the parathyroid glands and the juxtaglomerular apparatus. The effects of AII and hPTH(1-34) were antagonistic with little change in serum ionized calcium, intact PTH, or PRA when both were infused together. These interrelationships between the major hormonal systems controlling sodium and calcium homeostasis suggest a mechanism underlying the close association of calcium and sodium in the regulation of blood pressure.

Acute changes in serum osteocalcin during induced hypocalcemia in humans

Although levels of serum osteocalcin are thought to be an indicator of osteoblastic activity and bone formation, there is little information regarding the acute effects of changes in calcium or PTH levels on circulating osteocalcin concentrations. To study the effect of stepwise decreases in ionized calcium (CaI) on osteocalcin levels, we infused six normal subjects with citrate for four 30-min intervals using two different protocols. One protocol (pulse infusion) used alternating rates of infusion and resulted in rapid stepwise decrements in serum CaI. The second protocol (continuous infusion) used constant intermediate rates of citrate infusion and produced slower decrements in CaI, but with similar changes in magnitude. We monitored serum CaI, intact PTH, and osteocalcin concentrations during the course of these infusions. During each step of the pulse infusion the osteocalcin responses to changes in CaI in general were parallel to the changes in PTH (r = 0.462; P = 0.02) and were inversely correlated to CaI (r = -0.562; P = 0.003). The osteocalcin concentrations at the end of each 30-min period were higher than at the beginning of that period; over the total 120 min, osteocalcin levels rose from 3.46 +/- 0.63 to 6.88 +/- 1.08 micrograms/L (P less than 0.05). In contrast, during the first two periods of the continuous infusion, osteocalcin concentrations changed slightly. Only during the last two periods of the continuous infusion did osteocalcin respond in a manner characteristic of that observed with the pulse infusion. These data indicate that osteocalcin concentrations in the circulation may be acutely regulated by calcium and/or PTH.

Rate and concentration dependence of parathyroid hormone dynamics during stepwise changes in serum ionized calcium in normal humans

The relationship between circulating levels of PTH and the concentration and rate of change of ionized calcium (CaI) was studied in normal humans by measuring intact PTH during stepwise changes in CaI. Six normal subjects received two different citrate infusion protocols that produced stepwise decreases in CaI; one infusion produced a rapid decrement in calcium, and a second infusion produced a slower approach to the same (approximately 0.05 mmol/L) decline in calcium for each of four steps. The rapid decline in CaI resulted in a more marked increase in levels of PTH, which subsequently fell to levels similar to those with the slower infusion. For similar absolute changes in calcium, the mean maximal increment in PTH levels was significantly greater with the rapid infusion (36.4 +/- 3.1 ng/L) than with the slower infusion (19.4 +/- 2.1 ng/L; P = 0.001). Six additional subjects received infusions of citrate and calcium in a stepwise manner to induce either decreases or increases in CaI, followed by a return to baseline. During induced hypocalcemia, when calcium was changing slowly or not at all (i.e. at the plateau of each calcium change) PTH levels were not affected by the direction of change in calcium and appeared to be dependent upon the calcium concentration per se. At elevated levels of CaI, the PTH response to a stepwise decrease in calcium was blunted over that seen when CaI declined to or below baseline. Thus, the relationship between CaI and levels of PTH is dependent not only on the concentration but also on the rate of change in calcium, particularly during induced hypocalcemia; different rates of change in calcium result in different inverse sigmoidal relationships between PTH and CaI. When calcium is changing slowly or not at all, however, PTH levels appear to be dependent on the calcium concentration per se and are not affected by the previous direction or rate of change. Therefore, the role of the extracellular calcium concentration in the control of PTH secretion is part of more complex and dynamic regulatory mechanisms.