disease, type of immunocompromised state, and outcome of children with Epstein-Barr vi msâ€"induced lymphoproliferative disorders. MATERIALS AND METHODS. Medical records andimaging studies (from four tertiary children's medical centers) were reviewed for pathologically proven casesof lympho proliferative disorders in patients less than 20 years old. Trends between the CT imaging appearance,distribution, and type of immunocompromised state and prognosis were noted and analyzed with Fisher's exact test. RESULTS. Twenty-seven cases were identified (mean age, 7 years 8 months). Eighteenchildren had undergone solid organ transplantation (heart, n = 9; liver, n = 7; kidney, n = 2), and four had undergone bone marrow transplantation. Five patients had primary immunodefi ciencies. The CT appearance of lymphoproliferativedisordersvariedandincludedlymphade nopathy, focal mass or masses,and diffuse infiltration and enlargement of organs without focal mass. The distribution of disease included abdomen (n = 17), chest (n = 10), neck (n = 8), and brain (n = 1). In eight of nine heart transplant recipients, the disease predominantly in volved the chest and neck, whereas in all seven liver transplant recipients, the disease was iso lated to the abdomen (p = .001). The overall mortality rate of 44% was less related to anatomic extent (multiorgan, 46%; localized, 43%) than to type of immune dysfunction (p = .001): bone marrow transplantation (100%), primary immunodeficiency (80%), heart trans plantation (55%), liver transplantation (0%), and kidney transplantation (0%). CONCLUSION. Lymphoproliferative disorders inchildren Materials and MethodsMedical records from four tertiary children's medical centers were searched for pathologically proven cases of lymphoproliferativedisorders that occurredin immunocompromised patientslessthan 20 years old. Only patients in whom lymphoprolif erative disorders were documented by either biopsy A,CTscanshows multiple low-attenuation masses (largearrowheads) andpenportal area of low attenuation (small arrowheads) in segmental liventransplant. Masses engulf ratherthandisplace vascular structures (arrows). B,CTscanmoreinferior toA shows additional liverlesions, low-attenuation focalsplenic mass(arrow), and retropenitonealadenopathy(arrowheads). C,CTscanthrough lowerabdomen shows mesentenic mass (arrows) andsmallbowel loop (arrowheads) with wall thickening and dilatation. In these cases. imaging studies including radiog raphy. CT. MR imaging. and sonography were re viewed for the appearance and distribution of disease. The age. sex. type of immunocompromised state. treatment. and outcome of the patients were re viewed. Trends between the imaging appearance. distribution. and type of immunocompromised state and prognosis were noted and analyzed with Fisher's exact test. ResultsTwenty-seven patients were identi tied.Eighteen were boys. and nine were girls. The mean age was 7 years 8 months. with a range of 6 months to 19 years. Eighteen patients were immune-suppressed to prevent rejec tion of solid o...

Measurement of the atlas-dens interval is the radiographic standard for identification of patients with Down syndrome at high risk for neurologic injury from spinal cord compression. In 17 pediatric patients with Down syndrome, measurements of the atlas-dens interval, distance between the clivus and posterior odontoid process, and width of the neural canal obtained with plain radiographs were compared to predict the width of the subarachnoid space on magnetic resonance (MR) images. In all patients, cervical radiography and craniocervical MR imaging were prospectively performed during lateral flexion and extension. The width of the subarachnoid space was measured with MR imaging. When the 95% confidence interval for correlation coefficients of regression was used, subarachnoid space width on MR images correlated with neural canal width on radiographs better than with either atlas-dens interval or clivus-posterior odontoid process distance (P = .05). Measurement of neural canal width is a better predictor of potential spinal cord compression than the atlas-dens interval or clivus-posterior odontoid process distance and should be emphasized in screening examinations performed with plain radiography.

Nephroblastomatosis is an abnormality of nephrogenesis characterized by incomplete maturation of primitive nephrogenic cells. The resultant individual lesions have variable histologic findings and distribution in the kidney. There is wide acceptance of nephroblastomatosis as a precursor lesion to Wilms tumor. Consequently, the role of imaging in assessing patients for neoplastic transformation of nephroblastomatosis should be emphasized. Computed tomography (CT) has been shown to be superior to ultrasound (US) in this regard. Nonetheless, the low cost and lack of radiation of US make it attractive for serial screening studies. Although magnetic resonance imaging shows promise in assessment of the kidney for nephrogenic rests, experience is limited in its use in evaluating patients for nephroblastomatosis. The authors present protocols for assessing patients identified as being at either high or low risk for the development of Wilms tumor due to nephroblastomatosis. These protocols take into account the advantages of CT and US. Scanning intervals are determined from epidemiologic data on the occurrence of Wilms tumor; the most intense screening occurs during the younger ages of life, when the likelihood of Wilms tumor development is highest.

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