Vertebral osteoid osteoma masquerading as a malignant bone or soft-tissue tumor on MRI.

PURPOSE: Four pediatric patients were sent to our institution with the diagnosis of soft-tissue/malignant bone tumor. In all cases an MRI was the initial study performed for neck or back pain. All were surgically proven to have an osteoid osteoma/osteoblastoma (OO) as a final diagnosis. The MRI findings are reviewed. METHODS: Four patients, three boys and one girl, ranging in age from 5 to 17 years, presented with symptoms of neck or back pain for 2 months to 2 years. Two had neurological findings. All patients underwent MRI. RESULTS: All MRIs demonstrated decreased T1 signal and increased T2 signal in the soft tissues and bone surrounding the lesions consistent with edema. Enhancement was observed in the adjacent soft tissues and in the lesion nidus retrospectively. CONCLUSION: Investigating neck or back pain with an initial MRI may lead to misleading diagnoses unless the radiologist is aware of the typical MRI appearance of vertebral osteoid osteoma.

Imaging of the brain in the HIV-positive child.

The prevalence of human immune-deficiency virus (HIV) infection around the world, coupled with increasing population movement, make it likely that many physicians will treat HIV-infected patients. New treatment protocols for the specific manifestations of acquired immune-deficiency syndrome (AIDS) make distinguishing the different neurological diseases of great importance. The pattern of disease in children differs from those of adults both in its distribution and etiology. This article encapsulates the salient aspects relating to the imaging of the brain in HIV-positive children, paying particular attention to recent advances and the different features of the various pathological conditions affecting the HIV-infected brain in children.

Radiologic features of pediatric thalamic and hypothalamic tumors.

A variety of histologic subtypes of tumor may affect the thalamus and the hypothalamus in the pediatric population. These tumors have radiologic features that are useful in predicting pathology. We discuss the radiologic findings of childhood thalamic and hypothalamic tumors and provide imaging examples.

MRI features of intracranial and spinal ependymomas.

Intracranial and intraspinal ependymomas are uncommon tumors of the central nervous system. These tumors have a variety of imaging characteristics, some of which are fairly specific for ependymoma. We discuss the MRI features of ependymomas for each of the typical locations within the neuraxis, and provide MR imaging examples.

A CT scan technique for quantitative volumetric assessment of the mandible after distraction osteogenesis.

Distraction osteogenesis has become an accepted method of treatment for patients requiring reconstruction of hypoplastic mandibles. We present a quantitative analysis of volumetric changes after distraction osteogenesis in a series of 10 patients. Group I (n = 5 patients, 3 unilateral craniofacial microsomia, 1 Goldenhaar syndrome, and 1 bilateral craniofacial microsomia) underwent unilateral distraction of the mandible. Group II (n = 5 patients, 1 Nager syndrome, 1 bilateral craniofacial microsomia, 1 developmental micrognathia, and 2 Treacher Collins syndrome) underwent bilateral distraction of the mandible. Predistraction and postdistraction axial and three-dimensional computed tomographic (CT) scans were digitized and transferred to a computer for analysis with image-processing software to determine the changes in volume of the mandible and bony regenerate. The CT-derived volume method was validated by scanning three dry cadaver mandible specimens and comparing the volume data with those derived from a water-displacement method. The difference between the two methods was less than 5 percent. The mean distracted length, as recorded from the calibrated device, was 22.6 mm in the 10 patients. In the unilateral distraction group, the mean increase in hemimandibular bone volume was 2.8 cc, with a mean percentage increase of 27 percent in the distracted hemimandible. In the bilaterally distracted patients, the mean increase in total mandibular volume was 7.9 cc, with a mean percentage increase in bone volume of 25 percent. This study represents the first attempt to quantify the increase in bone volume resulting from distraction osteogenesis. Quantitative volumetric analysis of CT scans is an accurate method to measure the amount of bone regenerate in patients undergoing distraction osteogenesis of the mandible or the extremities. The concept and utility of quantifying the volumetric changes in bone following distraction osteogenesis may become more important as multiplanar devices are developed and used in other areas of the craniofacial skeleton.