Functional-metabolic imaging of neuroblastoma.

Neuroblastoma is the third most common malignant solid tumor of childhood. It originates from primitive neural crest cells of the sympathetic nervous system. Many imaging procedures help guide therapy and predict outcomes. Anatomic imaging methods, such as CT and MRI, are most useful for evaluation of the primary tumor mass and nearby involved lymph nodes. Functional imaging tracers, such as [123I]MIBG, [18F]FDG, and [99mTc]MDP, are used to assess the extent of disease and to search for distant metastases. [123I]MIBG is the principal functional imaging tracer for the detection and monitoring of neuroblastoma. [18F]FDG PET/CT is an alternative that is valuable in tumors with poor or no MIBG-uptake. [99mTc]MDP bone scans may be useful to assess cortical bone metastases. This article will review the use of [123I]MIBG and other functional imaging agents for the management of patients with neuroblastoma.

Multimodality imaging in the surgical treatment of children with nonlesional epilepsy.

OBJECTIVES: To evaluate the diagnostic value of individual noninvasive presurgical modalities and to study their role in surgical management of nonlesional pediatric epilepsy patients. METHODS: We retrospectively studied 14 children (3-18 years) with nonlesional intractable focal epilepsy. Clinical characteristics, surgical outcome, localizing features on 3 presurgical diagnostic tests (subtraction peri-ictal SPECT coregistered to MRI [SISCOM], statistical parametric mapping [SPM] analysis of [18F] FDG-PET, magnetoencephalography [MEG]), and intracranial EEG (iEEG) were reviewed. The localization of each individual test was determined for lobar location by visual inspection. Concordance of localization between each test and iEEG was scored as follows: 2=lobar concordance; 1=hemispheric concordance; 0=discordance or nonlocalization. Total concordance score in each patient was measured by the summation of concordance scores for all 3 tests. RESULTS: Seven (50%) of 14 patients were seizure-free for at least 12 months after surgery. One (7%) had only rare seizures and 6 (43%) had persistent seizures. MEG (79%, 11/14) and SISCOM (79%, 11/14) showed greater lobar concordance with iEEG than SPM-PET (13%, 3/14) (p<0.05). SPM-PET provided hemispheric lateralization (71%, 10/14) more often than lobar localization. Total concordance score tended to be greater for seizure-free patients (4.7) than for non-seizure-free patients (3.9). CONCLUSIONS: Our data suggest that MEG and SISCOM are better tools for lobar localization than SPM analysis of FDG-PET in children with nonlesional epilepsy. A multimodality approach may improve surgical outcome as well as selection of surgical candidates in patients without MRI abnormalities.

Dose reduction in pediatric hybrid and planar imaging.

Dose reduction in pediatric nuclear medicine involves many aspects of nuclear imaging. The computed tomography (CT) parameters used during the new hybrid imaging procedures, positron emission tomography (PET)/CT and single photon emission computed tomography (SPECT)/CT, involve trade-offs between image quality and effective dose. In this setting, CT may be used for diagnostic quality imaging, localization of scintigraphic abnormalities or attenuation correction only, with markedly different radiation exposures for each technique. The nuclear physician must select administered activities for PET and single photon imaging that provide quality imaging results at the lowest possible radiopharmceutical dosage. These administered activities must be adjusted appropriately for patient mass or age. Physical differences between PET and single photon imaging may require different adjustments for patient size. Dynamic imaging protocols should be reviewed to assure that frame rates appropriately track physiologic events and facilitate low administered activities. Optimal dose reduction in pediatric nuclear imaging requires attention to CT exposure parameters, administered activity and imaging protocols.

Altered mesolimbocortical and thalamic dopamine in Tourette syndrome.

We used [F-18]fallypride PET in six adults with Tourette syndrome and age-matched controls to assess extrastriatal dopamine 2 (D2) receptors. D2 receptor availability was significantly lower in the orbitofrontal cortex, primary motor cortex, anterior cingulate gyrus, mediodorsal nucleus of thalamus, and hippocampus, areas important for motivation and reward, sensory gating, movement, and attention. Altered dopaminergic function in mesolimbocortical systems and thalamus may contribute to increased motivational salience of tics.

Cultural influences on cognitive representations of conflict: interpretations of conflict episodes in the United States and Japan.

This article integrates theory from the cognitive tradition in negotiation with theory on culture and examines cultural influences on cognitive representations of conflict. The authors predicted that although there may be universal (etic) dimensions of conflict construals, there also may be culture-specific (emic) representations of conflict in the United States and Japan. Results of multidimensional scaling analyses of U.S. and Japanese conflict episodes supported this view. Japanese and Americans construed conflicts through a compromise versus win frame (R. L. Pinkley, 1990), providing evidence of a universal dimension of conflict construal. As the authors predicted, Japanese perceived conflicts to be more compromise-focused, as compared with Americans. There were also unique dimensions of construal among Americans and Japanese (infringements to self and giri violations, respectively), suggesting that identical conflict episodes are perceived differently across cultures.

The initial renal ultrasound examination in children with urinary tract infection: the prevalence of dilated uropathy has decreased.

BACKGROUND: Pelvocalyceal dilatation (PCD) is often detected by sonography during the prenatal period. Prenatal detection of PCD should affect the prevalence of PCD in children with urinary tract infection (UTI). PURPOSE: To determine the prevalence of abnormal sonographic findings in a population of children undergoing first imaging evaluations after UTI and to determine if the prevalence has changed from an earlier study at the same institution. MATERIALS AND METHODS: The findings on consecutive first renal and bladder sonographic examinations in 844 children (745 girls, 99 boys) with UTI were retrospectively reviewed. Cystograms were performed in 743/844 (494 nuclear, 249 fluoroscopic). Only children with known congenital malformations or other significant disease were excluded. RESULTS: Sonography was abnormal in 141/844 (16.7%). PCD was noted in 27/844 (3.2%), with mild PCD in 18/844 (2.1%) and moderate or severe PCD in 9/844 (1.1%). Hydroureter without PCD was noted in 6/844 (0.7%). Parenchymal abnormalities were present in 42/844 (5.0%) and bladder wall thickening in 43/844 (5.1%). Vesicoureteral reflux was present in 186/743 (25.0%). When compared to historical controls, PCD and hydroureter were significantly less prevalent than 1 decade earlier (P < 0.0001). CONCLUSION: The prevalence of PCD in children under first imaging evaluation for UTI declined significantly during the last decade. These data may be useful in the design of imaging strategies for children with UTI.

Vesicoureteral reflux: subpopulations of patients defined by clinical variables.

BACKGROUND: The first imaging evaluation of the child with urinary tract infection (UTI) is often the same for all children, regardless of the child's clinical presentation. However, this approach is simplistic and ignores considerable differences in the frequency of abnormal pathophysiology in different subpopulations of children with UTI. OBJECTIVE: Six clinical variables are evaluated as predictors of vesicoureteral reflux (VUR) in a large series of girls with UTI. MATERIALS AND METHODS: Data were collected from a consecutive series of 919 girls undergoing a first imaging evaluation for UTI. Six input variables were used: age, maximum body temperature (T(max)), number of UTIs, hospitalization, family history of childhood UTI, and rapidity of response to antibiotic therapy. The dependent variable was VUR. Data were enumerated and analyzed by logistic regression and the chi-square test. RESULTS: VUR was present in 28.8 %. The percentage with VUR varied from 56.1 % for age < 6 months and T(max) L 38.5 degrees C to 13.0 % for age L 10 years and T(max) < 38.5 degrees C. The frequency of VUR was significantly lower in girls with T(max) < 38.5 degrees C in most age groups. Logistic regression demonstrated, when all clinical variables were taken together, that only age and T(max) were independent predictors of VUR. CONCLUSIONS: Girls with UTI should not be considered to be a homogeneous group. The frequency of VUR is related to T(max) and inversely to age. Data about these subpopulations should be used in deciding which girls should undergo cystography.

Cyclic cystography: diagnostic yield in selected pediatric populations.

PURPOSE: To test the hypothesis that the diagnostic yield of cyclic cystography is related to the prevalence of vesicoureteral reflux (VUR) in the population being evaluated. MATERIALS AND METHODS: Two groups of children were examined prospectively: 124 with severe urinary tract infection, defined as patient hospitalization or a maximum temperature greater than 39.5 degrees C, and 135 with previously diagnosed VUR. Nuclear cystography was performed in 249 patients, and fluoroscopic cystography was performed in 10. If VUR was not seen during the first cycle of bladder filling and voiding, a second cycle was performed. RESULTS: VUR was present during cycle 1 in 40 (32%) of 124 patients with severe urinary tract infection and 90 (67%) of 135 children in the VUR follow-up group (P < .001). VUR was demonstrated during cycle 2 in seven (9%) of 76 of the severe urinary tract infection group and eight (24%) of 34 of the VUR follow-up group (P = .045). Of 15 patients with VUR during cycle 2, two had grade III VUR and 13 had grade I or II VUR. CONCLUSION: The second cycle of cyclic cystography has a higher diagnostic yield in patients undergoing VUR follow-up than in patients with severe urinary tract infection. The decision to perform a second cycle of bladder filling and voiding should take into account the pretest probability of VUR in the child being examined.

Dosimetry of pediatric nuclear medicine procedures.

BACKGROUND: Radiation dose estimates for children of different ages for many different nuclear medicine procedures are presented. METHODS: Using standard MIRD methodology, radiation dose calculations were performed for a broad range of radiopharmaceutical agents commonly used in pediatric nuclear medicine. Results from the best available biokinetic models were used in the MIRDOSE 3.1 computer program to obtain dose estimates per unit administered activity for the procedures. Then, assuming typical values of administered activity based on body weight, the dose per procedure for many target organs of interest was calculated and presented in tabular form. The effective dose equivalent (ICRP 30) and effective dose (ICRP 60) are also given. RESULTS AND CONCLUSIONS: The results are presented in multiple tables attached to the text of the article. The information should be quite useful in evaluating radiation doses for many pediatric nuclear medicine procedures, using the best available models and methods.