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Purpose: To characterize the maturational changes in water diffusion within central gray matter nuclei and central white matter pathways of the human brain by using diffusion-tensor magnetic resonance (MR) imaging., Materials and Methods: Retrospective analysis of normal MR examination findings in 153 subjects (age range, 1 day to 11 years) referred for clinical neuroimaging was performed. All studies included diffusion tensor-encoded echo-planar MR imaging. Isotropic diffusion coefficient (D) and diffusion anisotropy (A(sigma)) were measured in the corpus callosum, internal capsule, caudate nucleus, lentiform nucleus, and thalamus., Results: exhibited biexponential decay with age in gray and white matter regions, except for monoexponential decay in the genu of the corpus callosum. There was a steep nonlinear increase of A(sigma) in white matter tracts that paralleled the time course of the decline in D. In basal ganglia, only a small linear increase in A(sigma) was observed in patients. A(sigma) changes in the thalamus were intermediate between basal ganglia and white matter structures., Conclusion: Changes in magnitude and anisotropy of water diffusion follow stereotypical time courses during brain development that can be empirically described with multiexponential regression models, which suggests that quantitative scalar parameters derived from diffusion-tensor MR imaging may provide clinically useful developmental milestones for brain maturity.

Purpose: To determine the usefulness of technetium 99m diethyltriaminepentacetic acid (DTPA) radioaerosol inhalation-clearance scintigraphy for early detection of pulmonary complications of human immunodeficiency virus (HIV) disease in children., Materials and Methods: A total of 301 studies were performed in 132 HIV-positive children (group 1; mean age, 46.6 months). In children born to HIV-positive mothers (group 2), 273 studies were performed in 160 children who eventually were proved to be HIV negative (mean age, 10.3 months), and 80 studies were performed in 47 HIV-positive children (mean age, 15.6 months). Radioaerosol studies were performed by using commercially available radioaerosol nebulizers. Pulmonary clearance half-time was measured by using conventional gamma camera computer systems. Radioaerosol results were correlated with indexes of pulmonary health and function., Results: The HIV-negative, group 2 children had a mean radioaerosol clearance half-time (58.1 minutes; 162 studies in 108 children) similar to that reported in healthy adults. Group 1 children with pulmonary involvement exhibited a faster mean clearance half-time (28.6 minutes) than did children without evidence of pulmonary involvement from either group 1 or group 2 (P < .05). A faster pulmonary clearance rate did not simply reflect the presence of chest disease that also was detectable on radiographs (P = .3)., Conclusion: Quantitative DTPA radioaerosol clearance studies may provide useful information about pulmonary involvement in selected children with HIV disease.

Purpose: To illustrate abnormalities detected with radionuclide skeletal scintigraphy, computed tomography (CT), and radiography after bone marrow harvest in patients who are candidates for autologous bone marrow transplantation (ABMT) in treatment of neuroblastoma., Materials and Methods: Twenty-four patients with neuroblastoma underwent ABMT and evaluation with conventional skeletal scintigraphy. Findings of abnormality on bone scans were correlated whenever possible with findings from CT and plain radiography., Results: Skeletal scintigraphy revealed 36 sites of increased activity in the sacroiliac region, iliac crest, or both caused by bone marrow harvest in the 24 patients. In 10 patients, follow-up bone scans showed complete disappearance of abnormal activity at 18 sites., Conclusion: The harvesting of marrow for ABMT caused iatrogenic abnormalities on bone scans. It is important that these be recognized so that they will not be confused with progressive or new metastases.

A subperiosteal abscess is an uncommon complication of osteomyelitis in childhood. Bone scanning is very sensitive for the detection of early skeletal infection; however, a subperiosteal abscess has a different and distinctive scintigraphic appearance. The usual increased tracer uptake of osteomyelitis is overshadowed by the presence of a "cold" lesion on the delayed views, probably due to interruption of the vascular supply of the bone. Early recognition of the condition is important, as surgery is indicated to prevent extensive bone necrosis and chronic osteomyelitis. In suspected osteomyelitis, a central photopenic area is highly suggestive of subperiosteal abscess; when such an area is seen, a computed tomographic (CT) scan can be helpful in planning the surgical approach for drainage. Plain radiographs may be unremarkable even when the bone scan and CT findings are dramatic. Five such cases are presented, and a recommended diagnostic approach is discussed that views the two procedures as complementary.

The treatment and prognosis of sellar region masses in children differ according to the type of tumor, and thus accurate determination of the extent and characteristics of the lesion is important. Evaluation by conventional skull radiography, complex-motion tomography, radionuclide imaging, computed tomography, cerebral air studies, and cerebral angiography has demonstrated definable characteristics of the various types of tumors and often allows distinction from benign processes.

Cystic hepatoblastomas share ultrasonographic characteristics with simple hepatic cysts; however, a distinction can be made by the demonstration of internal septations. The differentiation is important because cystic hepatoblastoma may have malignant potential. The ultrasonographic and scintigraphic findings in five children with cystic hepatoblastoma are reviewed.

Radionuclide and computed tomographic (CT) scanning was performed for the long-term follow-up of 63 patients who had been treated for primary intracranial central nervous system tumors. This group included 23 children with supratentorial lesions and 40 with infratentorial lesions. The results of imaging were correlated with clinical assessment and the results of cytologic evaluation of the cerebrospinal fluid and, when available, surgical or autopsy findings. The sensitivity, specificity, and positive predictive value of both CT and radionuclide scanning were evaluated for each type of tumor. These two modalities play a complementary role in the long-term follow-up of children with primary intra-axial neoplasms.

In seven children with small bowel lymphoma, gray scale ultrasound correctly identified the pathological process, as well as excluded the kidney, liver, and adrenal as the site of origin. In all cases, thickened bowel wall and exoenteric masses were identified. Surgical confirmation was obtained in all patients.

A two-month-old girl with congenital syphilitic hepatitis had bizarre liver scintigraphic features showing diminished hepatic uptake of radiocolloid with accentuated pulmonary and bone marrow accumulation. These features were reversible following penicillin therapy and to our knowledge are previously undescribed manifestations of this multisystemic disease.

Thyroid dysgenesis is often manifested by a lingual or sublingual location of the thyroid gland. If radionuclide studies are not readily available or are contraindicated, ultrasound (US) may be used to locate the gland. The US appearance of a lingual thyroid gland and the role of US in the evaluation of suspected thyroid dysgenesis are described.

The authors have encountered benign liver masses as frequently as malignant lesions in children with hepatomegaly. Lesions studied included abscesses, cavernous hemangioma/hemangioendothelioma, adenoma of glycogen storage disease, choledochal cysts, focal nodular hyperplasia, cystic hepatoblastoma, and hamartoma. An integrated imaging protocol involving ultrasound, computed tomography, and scintigraphy proved to be more helpful than any one modality in establishing the benign or malignant nature of a hepatic neoplasm and the type of tumor, which is of particular importance when surgical exploration and/or biopsy is contraindicated.

Both the prognosis and treatment of hepatic tumors in children depend upon the histological diagnosis and the extent of disease. Recent advances in imaging techniques permit characterization of specific tumors and differentiation from other intrahepatic processes. An integrated imaging protocol involving a combination of ultrasound, computed tomography, and scintigraphy often provides a high degree of accuracy. Patterns derived from 40 cases of hepatoblastoma, hepatocellular carcinoma, rhabdomyosarcoma, monotypic small-cell sarcoma, and metastatic tumors are discussed and an algorithm for evaluation of hepatic tumors in children is presented.

Four children with acute leukemia and surgically documented candidiasis of the liver and/or spleen were examined with a combination of diagnostic imaging modalities including 99mTc-sulfur colloid and 67Ga-citrate scintigraphy, gray-scale ultrasound, and body computed tomography (CT). Abnormalities were detected in every individual examined. 99mTc-sulfur colloid scintigraphy revealed "cold" areas in the liver or spleen. With 67Ga scintigraphy, these areas were "cold" in some individuals and "hot" in others. Gray-scale ultrasound demonstrated hypoechoic lesions with central areas of increased echogenicity in hepatic involvement, and hypoechoic replacement of the spleen in splenic involvement. CT in one patient revealed low-density areas without contrast enhancement within the hepatic parenchyma and unsuspected renal involvement.

Deep venous thrombophlebitis may escape clinical detection. Three cases are reported in which whole-body gallium 67 scintigraphy was used to detect unsuspected deep venous thrombophlebitis related to indwelling catheters in three children who were being evaluated for fevers of unknown origin. Two of these children had septicemia from Candida organisms secondary to these venous lines. Gallium 67 scintigraphy may be useful in the detection of complications of indwelling venous catheters.

Automated water path ultrasound scanning was used to examine 15 infants and children with suspected spinal dysraphism. The spinal abnormalities demonstrated by ultrasound included meningocele, myelomeningocele, and spinal lipoma. In addition, renal abnormalities (pyelocaliectasis and hydronephrosis) were seen in 5 patients. It is concluded that ultrasound examination of the neural axis should play an important role in evaluation of children with spinal dysraphism.

Water path ultrasound scanning of the abdomen was used to evaluate 103 children with clinically apparent disorders of the gastrointestinal tract. Dynamic ileus was distinguished from adynamic ileus, congenital disorders were identified, tumors of the bowel wall were distinguished from vascular lesions, and thickening of the bowel wall in metabolic and toxic disorders was seen. Traumatic and inflammatory conditions were evaluated successfully in 17 patients, obviating the need for barium gastrointestinal studies in these children. Given the benign nature of ultrasound, the authors believe that ultrasound examinations of the bowel should be used with greater frequency, particularly in children.

Thickening of the bladder wall and dilatation of the prostatic urethra can be shown by ultrasound in infants with posterior urethral valves. This can be helpful in the diagnosis of hydroureter. Marked hypertrophy of the bladder muscle can appear as solid echogenic mass and simulate a pelvic tumor. Ultrasonic findings in 5 infants with posterior urethral valves are reviewed.

While contact ultrasound has been used to assess the pleural space, pulmonary parenchyma, and mediastinum, there have been many difficulties owing to attenuation by bone and air interfaces. The authors have obtained excellent results using water-path ultrasound in 82 children with benign and malignant thoracic disease. The physical characteristics of the water path and the ability to scan dependent portions of the chest in various planes facilitated identification and characterization of lesions involving the chest wall, pleura, parenchyma, and mediastinum.

In hepatic tumors seen in children, treatment and prognosis differ from tumor to tumor and thus accurate determination of their extent and characteristics is important. Evaluation by gray scale ultrasonography, radionuclide imaging and angiography has produced definable characteristics for the various tumor types and often allows distinction from other intrahepatic processes. In addition, chemotherapeutic treatment of initially unresectable malignant hepatic tumors can be followed by nuclear imaging, ultrasound and angiography to determine therapeutic response.