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Purpose: (131)I-MIBG provides molecularly targeted radiotherapy for pediatric neuroblastoma patients with relapsed or refractory disease. At our institution, designated family caregivers and nurses participate in the care of the child during hospital isolation for approximately 3-5 days post-administration. The purpose of this study was to measure radiation exposure to family caregivers and nurses caring for children with neuroblastoma during their stay in the hospital for (131)I-MIBG therapy., Methods: Iodine-(131)I-MIBG therapy was administered to 14 children (mean age 6.7 ± 3.8 years, range 3-13 years) for relapsed or refractory neuroblastoma from 2009 to 2010. The administered activity ranged from 5.92 to 23.31 GBq (mean 13.65 ± 5.22 GBq). The mean administered activities were 8.77 ± 2.07 GBq (range 5.92-11.1 GBq) and 17.32 ± 3.4 GBq (range 11.84-23.31 GBq) for children less than 7 and 7 years or older, respectively. One or two designated caregivers received specific radiation safety training prior to treatment. One caregiver was allowed to stay in a room adjacent to the child to provide general patient care as instructed by nursing. Nurses assigned to the care of the patient also received specific radiation instructions. The total caregiver and nursing whole body radiation dose was determined using real-time personal dosimetry., Results: There was no correlation between caregiver (r = -0.068, P = 0.817) or nursing (r = -0.031, P = 0.916) whole-body radiation dose and the patient-administered activity. The overall mean caregiver radiation dose was 1.79 ± 1.04 mSv, but the range of caregiver radiation doses varied by more than an order of magnitude (0.35-3.81 mSv), with no caregiver receiving more than 4.0 mSv. The overall mean nursing radiation dose was 0.44 ± 0.27 mSv per treatment, ranging from 0.15 to 1.08 mSv, with no nurse receiving more than 1.1 mSv. When grouped by patient age, there was no significant difference (P = 0.673) in the mean caregiver exposure for children less than 7 years, 1.94 ± 1.17 mSv (n = 6, range 0.7-3.81 mSv), compared to 1.69 ± 0.99 mSv (n = 8, range 0.35-3.37 mSv) for children 7 years or older. Similarly, there was no significant difference (P = 0.511) in mean nursing exposure for children less than 7 years, 0.5 ± 0.31 mSv (n = 6, range 0.18-1.08 mSv), compared to 0.4 ± 0.24 mSv (n = 8, range 0.15-0.94 mSv) for children 7 years or older., Conclusion: There was no significant correlation between caregiver or nursing radiation exposure and patient-administered activity or no significant difference between patient age. This may suggest that older children who tend to receive higher administered activities may require less direct caregiver support during their hospital stay. Most importantly, all caregivers and nurses received radiation doses allowed under current regulations for individuals exposed to therapy patients during hospital isolation (<5.0 mSv), although this does not include exposure the caregivers may receive once the patient leaves the hospital.

Objective: The purpose of this study was to automate volume measurement of pediatric kidneys using Technetium-99m-dimercaptosuccinic acid (99mTc DMSA) SPECT. Assessment of renal size is essential in making an accurate clinical diagnosis and in evaluating normal and abnormal renal growth. Existing techniques for measuring renal length and volume are often observer-dependent and are limited by interobserver variability., Materials and Methods: An automated method using 99mTc DMSA SPECT was developed to measure renal length, volume, and 2D/3D split renal functions. An adaptive threshold was used for segmentation of renal images. To improve measurement accuracy of renal volumes, a boundary-weighted integration and a linear correction from phantom experiments were applied. Using the new automated software, we evaluated 620 normal kidneys in 310 patients aged 1 to 21 years., Results: In all, 99.4% of renal volume measurement was inter-/intraobserver reproducible without manual intervention. Correlations between renal size (volume and length) and growth parameters (age and body weight) were evaluated by nonlinear regression modeling. Body weight was found to be the best predictor of kidney volume and length (P < 0.0001). Normal ranges were established according to body weight., Conclusions: Automatic renal volume measurement with 99mTc DMSA SPECT demonstrates high observer reproducibility, and it is useful for achieving accurate assessment of renal growth using sequential measurements. The renal growth models generated by this study will aid physicians in evaluating and monitoring renal growth.

Purpose: Skeletal scintigraphy is an important method for showing evidence of stress injuries affecting the partes interarticulares of young athletes with low back pain. Other etiologies of low back pain may also cause uptake abnormalities in these patients. How often do the results of skeletal scintigraphy support diagnoses other than stress injuries to the partes interarticulares and what are these diagnoses?, Materials and Methods: We retrospectively reviewed the records of 209 young patients (149 females, 60 males; age range: 8-21 years, mean: 15.7 years) with low back pain and no previously treated vertebral condition who were consecutively referred from a sports medicine clinic to skeletal scintigraphy., Results: Sites of high uptake supportive of diagnoses other than pars interarticularis stress were shown in 36 (17%) of the 209 patients. Other diagnoses supported by skeletal scintigraphy included stress at the articulation between a transitional vertebra and the sacrum, injuries to the vertebral body ring apophysis, sacral fracture, spinous process injury, and sacroiliac joint stress., Conclusion: Skeletal scintigraphy shows uptake abnormalities supportive of diagnoses other than pars interarticularis stress in a significant number of young patients with low back pain. The uptake abnormalities shown are usually stress-related in this select population.

Aneurysmal bone cyst is an uncommon nonneoplastic lesion that occurs predominantly during the first 2 decades of life. Angiographic- and tissue-phase imaging provided more striking evidence of this unexpected lesion than skeletal-phase imaging in a 13-year-old girl with pain in the right buttock and posterior thigh.

Skeletal tracer localization in the rectus abdominis muscle of a 17-year-old girl whose training regimen included vigorous abdominal exercise but who had no abdominal soreness is described. The case illustrates that bone tracers may localize to skeletal muscle without associated symptoms. This is consistent with bone tracer localization in skeletal muscle reflecting subtle fiber abnormalities rather than necrosis.

Purpose: This study assesses the contribution of renal cortical scintigraphy in the diagnostic evaluation of infants with ectopic ureteroceles., Methods: The records of 20 infants (age range, 3 weeks to 4 months) who were referred for renal cortical scintigraphy after an ectopic ureterocele associated with a duplex kidney was found during follow-up of prenatal hydronephrosis were reviewed retrospectively. All infants underwent voiding cystourethrography, ultrasonography, and Tc-99m DMSA scintigraphy., Results: All upper moieties showed absent or depressed Tc-99m DMSA uptake. Upper moiety functional impairment was associated with structural abnormalities shown by ultrasonography. The degree of functional impairment was reflective of ultrasonographically defined cortical thickness relative to pelvic diameter, but this relation varied. Eight of 20 (40%) lower moieties had diffusely depressed relative Tc-99m DMSA uptake. Focal defects were also present in three of these eight (38%) lower moieties. Lower moiety functional impairment was associated with higher degrees of pelvic dilatation and with vesicoureteral reflux. Ultrasonography revealed diffuse parenchymal thinning in four of the eight (50%) lower moieties with depressed uptake. Ultrasonography did not define focal parenchymal loss in any lower moiety., Conclusions: The degree to which function is impaired in the upper moieties of duplex kidneys with ureters terminating in ectopic ureteroceles is not highly predictable by ultrasonography. Lower moiety functional impairment and cortical defects are frequently present in these kidneys and often occur without ultrasonographic evidence of parenchymal damage. Use of renal cortical scintigraphy in the diagnostic evaluation of infants with ectopic ureteroceles is supported.

Nuclear medicine is important in the diagnosis, staging, and long-term surveillance of a number of pediatric cancers. Skeletal scintigraphy is used to evaluate primary skeletal cancers, such as osteosarcoma and Ewing sarcoma, and nonskeletal cancers such as neuroblastoma, lymphoma, medulloblastoma, rhabdomyosarcoma, and retinoblastoma. Metaiodobenzylguanidine scintigraphy is valuable in examinations of children with neuroblastoma. The therapeutic response of primary bone and brain tumors can be assessed using Tl-201 and Tc-99m MIBI scintigraphy. Imaging strategies for staging and monitoring the therapeutic response of Hodgkin's lymphoma include Ga-67 citrate scintigraphy. Pediatric oncologic applications of positron emission tomography are being investigated extensively.

The authors present a case in which skeletal scintigraphy helped them to differentiate an anterior tibial stress fracture from a possible osteoid osteoma. Important scintigraphic clues to the correct diagnosis included a linear rather than a round to oval configuration to the focus of intense uptake shown by pinhole imaging, absence of focally increased tracer localization on the angiographic and tissue phases, and a symmetrically positioned, less-conspicuous contralateral abnormality.

Purpose: To apply postprocessing techniques to register three-dimensional TI-201 bone SPECT datasets with MRI. This may provide more accurate anatomic-functional correlation when localizing active tumors., Materials and Methods: Three-dimensional datasets were constructed from previously acquired MRIs using routine imaging protocols. Registration software was used to coregister the TI-201 SPECT studies and the MRIs in three dimensions., Results: Adequate TI-201 uptake in muscles and soft tissues along with relatively low accumulation in tendons and joint spaces provided adequate landmarks for visually aligning SPECT and MRI datasets. MR abnormalities were more extensive because of surrounding reactive tissue, and more focal TI-201 uptake could be demonstrated within the region of MR signal abnormality, allowing the focal metabolically active tissue to be distinguished from adjacent edema., Conclusions: Image registration of SPECT and anatomic imaging (CT or MRI) is used routinely to evaluate functional abnormalities within the brain. This technique has now been applied to the combination of TI-201 SPECT and MR data for evaluating bone lesions and may provide additional anatomic information for localizing functional abnormalities. This may be valuable for defining targets for biopsy, planning surgical treatment, and using minimally invasive therapies.

To compare the detection rate of renal cortical defects with Tc-99m dimercaptosuccinic acid (DMSA) using triple-detector SPECT, pinhole, and planar cortical scintigraphy, the authors prospectively studied 80 kidneys in 40 patients (26 males, 14 females) who ranged in age from 3 months to 26 years (mean: 7.5 years). They found single or multiple definite defects in 30 kidneys using SPECT, 23 using pinhole imaging, and 17 using planar imaging (McNemar's test, two-tailed, P < 0.001 and P = 0.03, respectively). SPECT was significantly better than pinhole imaging at demonstrating definite defects (P = 0.008). This study indicates that SPECT, and to a lesser extent pinhole, are superior to planar imaging for conclusively demonstrating renal cortical defects.

Purpose: To describe scintigraphic characteristics of bone allografts used in limb salvage reconstruction after resection of lower extremity osteosarcoma., Materials and Methods: The authors reviewed 85 skeletal scintigrams of 20 pediatric patients followed up for 0.5-5.7 years after resection of lower extremity osteosarcoma and allograft reconstruction. Uptake in the allograft and adjacent host tissues was assessed visually., Results: Lack of tracer uptake in the allografts was seen in 99% of the studies and a faint rim of tracer localization outlining the allograft's periphery was seen in 95% of the studies. Increased uptake was noted at the allograft-host bone junction in 78% of the studies. Uptake was increased in the joint surfaces of native bones articulating with allografts (97% of studies), including the patella (93% of studies) when the knee was involved. These findings were stabilized as time passed., Conclusion: Cadaveric bone allografts have a characteristic scintigraphic appearance in this selected patient group that reflects the physiology of their incorporation process.

Localization of skeletal tracer in a neuroblastoma primary is common but localization in extraskeletal metastatic sites has not received recognition. Tc-99m MDP concentration in hepatic or pulmonary metastases was noted in three of ten patients with such metastases. Lesion size appears to be important for demonstrating these metastases with Tc-99m MDP. This was particularly true for hepatic metastases, which were identified only when they were 5 cm or greater in diameter.

A 17-year-old boy with chest pain and severe bronchospasm underwent lung imaging to exclude pulmonary embolism. This showed widespread nonsegmental defects in both the ventilation and perfusion scans. A repeat study performed immediately after nebulized bronchodilator administration was normal apart from changes consistent with left lower lobe pneumonia and atelectasis which had subsequently evolved on the chest radiograph. Bronchodilator administration is valuable in improving the accuracy of lung scanning in asthmatic patients by reducing the perfusion and ventilation abnormalities caused by hypoxia-induced vasoconstriction.

This is a report of serial Tc-99m DMSA renal imaging on a pediatric patient with renovascular hypertension that experienced a complication of angioplasty. The case dramatically illustrates the usefulness of this radiopharmaceutical in the evaluation of acutely worsening hypertension, and in monitoring improvement following arterial revascularization for significant branch stenosis.

Thirty-eight patients (28 boys and 10 girls) with hip pain were referred for bone scans. In 7 of 8 with Legg-Calvé-Perthes disease, there was decreased uptake of the radiopharmaceutical in the proximal femoral epiphysis; the other had radiographic evidence of joint destruction and showed increased uptake. Three patients with abnormal scans had normal x-rays with Gaucher's disease, toxic synovitis, and Legg-Calvé-Perthes disease, respectively. One patient with avascular necrosis associated with steroid therapy had increased uptake, possibly due to revascularization. Those with toxic synovitis had either normal bone scans for showed a slight generalized increase around the hip joint. It is speculated that the latter may represent those who later present with Legg-Calvé-Perthes. The bone scan is useful for the early detection of Legg-Calvé-Perthes disease in patients with hip pain.

Osteoid osteoma is a painful osteoblastic process. The pre-operative diagnosis is usually made by roentgenogram. Four surgically confirmed cases are examined where the preoperative diagnosis was clarified by bone scintigraphy. The clinical indications, the diseases process, the literature are reviewed.