Biomedical subjects
Publications and source records attributed to R A Zimmerman.
We report medullary injury during adenoidectomy in two children who received injections of local anesthetic agents into the operative bed. Initial manifestations included hemiparesis, nystagmus, and ataxia. Magnetic resonance imaging showed hemorrhagic, paramedian medullary lesions in both patients. The mechanism of injury is likely to be injection of fluid into the medulla.
OBJECTIVE: To determine whether children with homozygous sickle cell anemia (SCD) who have silent infarcts on magnetic resonance imaging (MRI) of the brain are at increased risk for overt stroke. METHODS: We selected patients with homozygous SCD who (1) enrolled in the Cooperative Study of Sickle Cell Disease (CSSCD) before age 6 months, (2) had at least 1 study-mandated brain MRI at age 6 years or older, and (3) had no overt stroke before a first MRI. MRI results and clinical and laboratory parameters were tested as predictors of stroke. RESULTS: Among 248 eligible patients, mean age at first MRI was 8.3 +/- 1.9 years, and mean follow-up after baseline MRI was 5.2 +/- 2.2 years. Five (8.1%) of 62 patients with silent infarct had strokes compared with 1 (0.5%) of 186 patients without prior silent infarct; incidence per 100 patient-years of follow-up was increased 14-fold (1.45 per 100 patient-years vs 0.11 per 100 patient-years, P =.006). Of several clinical and laboratory parameters examined, silent infarct was the strongest independent predictor of stroke (hazard ratio = 7.2, P =.027). CONCLUSIONS: Silent infarct identified at age 6 years or older is associated with increased stroke risk.
PURPOSE: To determine the utility of using quantitative apparent diffusion coefficient (ADC) values as an objective means of early detection of brain injury caused by hypoxic-ischemic encephalopathy (HIE) in term neonates. MATERIALS AND METHODS: Conventional images, diffusion-weighted images, ADC maps, and clinical charts from 13 term neonates clinically suspected of having HIE were retrospectively reviewed. Four term neonates without HIE served as control subjects. ADC values were calculated in predefined regions in patients and compared with those in control subjects. A Student t test was performed for each region to compare patients and control subjects. RESULTS: Abnormalities were more easily detected on diffusion-weighted images and ADC maps, compared with conventional images. ADC values in patients with HIE were significantly different from those of control subjects in the posterior limb of the internal capsule, corona radiata, posterior frontal white matter, and parietal white matter bilaterally. CONCLUSION: Evaluation of ADC maps can improve conspicuity of hypoxic-ischemic injury in the acute and/or subacute setting (within 12 days of insult), and calculation of ADC values can provide an objective measure of hypoxic-ischemic injury.
We present the cranial MRI findings in a 6-month-old girl with biopsy-proven acute neuropathic Gaucher's disease, which include unilateral cerebral atrophy and dural thickening with contrast enhancement.
In the first of two experiments (20 to 70 wk of age), eight treatments consisted of corn-soybean meal diets (0.34% total P, 3.8% Ca, 17% CP, 2,758 kcal ME/kg) containing 0.10, 0.15, 0.20, 0.25, or 0.45% available P (AP), with the three lowest AP diets supplemented with 300 units of phytase/kg of diet. A second experiment evaluated the effect of feeding the 0.10% AP diet with and without phytase on performance and time required for onset of P deficiency in older hens (70 to 76 wk of age). In Experiment 1, the 0.10% AP diet with no supplemental phytase depressed performance by 28 wk of age. No other significant differences in performance were observed among treatments for the entire 20- to 70-wk period except that the 0.15% AP diet with no phytase resulted in body weights and tibia ash that were lower (P < 0.05) than those of hens fed the 0.45% AP diet during the last 30 wk. The mean daily AP intake of hens fed the 0.10% AP, 0.15% AP, 0.45% AP, or 0.10% AP + phytase diets was 94,159, 499, or 108 mg, respectively. Excreta P concentration was decreased by approximately 50% in birds consuming 0.10% AP + 300 U/kg phytase compared with those consuming 0.45% AP. In the second experiment, P deficiency signs occurred within 3 wk of consuming the unsupplemented corn-soybean meal diet (0.10% AP) compared with 8 wk in Experiment 1. The results of this study indicate that phytase improves P utilization in corn-soybean meal diets for laying hens and that a corn-soybean meal diet containing 0.15% AP (159 mg AP/d) or containing 0.10% AP + 300 units of phytase/kg (108 mg AP/d) supported optimal egg production from 20 to 70 wk of age. Additionally, results suggested that older hens may exhibit P deficiency symptoms sooner than younger hens.
Neurofibromatosis type I (NF-1) belongs to a family of diseases named phakomatoses, which are characterized by congenital malformations of ectodermal structures. Neurofibromatosis type I affects 1 in 3000 people, and has a diverse clinical presentation as well as an array of imaging findings. In this article the authors review the various neuroimaging findings present in NF-1, including abnormalities of the parenchyma, meninges, vessels, and associated neoplasms.
OBJECTIVE: The purpose of our study was to determine if a standard imaging protocol using ultrafast MR sequences could adequately reveal normal posterior fossa anatomy in fetuses and, if so, to document a template on MR imaging for normal posterior fossa development. MATERIALS AND METHODS: A retrospective review found 66 MR imaging studies of 63 fetuses, 16-39 weeks' gestation age (mean, 25 weeks' gestation), who were referred between June 1996 and May 1999 for evaluation of non-central nervous system anomalies revealed on prenatal sonography. All fetuses had normal brains and spines on prenatal sonography. The standard MR imaging protocol included axial, sagittal, and coronal half-Fourier acquisition single-shot turbo spin echo (HASTE); sagittal and coronal two-dimensional fast low-angle shot (FLASH); and axial turbo T1-weighted FLASH images through the fetal brain. Structures that we analyzed were the fourth ventricle, the cisterna magna, the vermis, the cerebellar hemispheres, and the brainstem. Using the HASTE sequences, we documented gestational age-specific signal intensity changes in the cerebellar hemispheres and the brainstem. RESULTS: The posterior fossa anatomy was sufficiently well defined to exclude abnormalities of the fourth ventricle and cerebellar vermis in all cases. Because of high T2-weighting, good contrast enhancement, and good signal-to-noise ratios, HASTE images provided the best anatomic definition of the posterior fossa. CONCLUSION: Normal posterior fossa anatomy can be adequately shown on ultrafast MR images, which can be helpful when prenatal sonography is equivocal.
OBJECTIVE: This study compares the relative efficacy of two fast T2-weighted MR imaging techniques-fast imaging with steady-state free precession (true FISP) and half-Fourier acquisition single-shot turbo spin-echo (HASTE)-in the evaluation of the normal fetal brain maturation during the second and third trimesters of gestation. SUBJECTS AND METHODS: The brain maturation of 10 normal nonsedated fetuses (5 during the second trimester and 6 during the third trimester of gestation [1 fetus underwent 2 examinations]) was examined by both techniques using a Vision+ 1.5-T MR system. We specifically looked for developing events, including white matter myelination, neuronal migration, and cortical sulcation. Image quality was graded according to the presence or absence of undesirable blurring. RESULTS: The specific absorption rate was lower for true FISP than for HASTE by a factor of 3 at equivalent imaging conditions. HASTE and true FISP provide comparable image quality in the second trimester when myelination of the cerebrum has not begun. Neuronal migration could be recognized as hypodense bands on both sequences during the second trimester. Myelination beginning at the third trimester was better delineated with true FISP than with HASTE because of point spread function-related blurring effects inherent in HASTE that hampered visualization of short-T2 structures. Cortical sulcation was well delineated by both sequences. CONCLUSION: With relatively superior image quality and significantly lower radiofrequency absorption than HASTE, true FISP is a safer and more effective alternative in the prenatal evaluation of normal fetal brain.
OBJECT: Injuries of the occipitoatlantoaxial (Oc-C2) region are the predominant form of cervical injury in children younger than 10 years of age. Magnetic resonance (MR) imaging can be used to visualize directly the traumatic ligamentous and soft-tissue abnormalities of the Oc-C2 region. A retrospective review was undertaken to examine the spectrum of pediatric Oc-C2 injuries seen on MR imaging, their correlation with plain x-ray film and computerized tomography findings, and their clinical course. METHODS: Seventy-one consecutive children younger than 10 years of age underwent cervical MR imaging for evaluation of traumatic injury. Magnetic resonance imaging was used to document abnormalities in 23 children; 20 of these injuries involved the Oc-C2 region. Abnormalities in the Oc-C2 region included disruptions of the musculature, apical ligament, atlantooccipital joint(s), tectorial membrane, and spinal cord. A spectrum of injury with progressive involvement of these structures was seen, ranging from isolated muscular injury to the multiple soft-tissue and ligamentous disruptions with craniocervical dislocation. Involvement of the tectorial membrane was the critical threshold in the transition from stable to unstable injury. Analysis of plain x-ray films revealed that a novel interspinous C1-2:C2-3 ratio criteria of greater than or equal to 2.5 was predictive of tectorial membrane abnormalities on MR imaging, with 87% sensitivity and 100% specificity. In patients with tectorial membrane abnormalities who underwent immobilization alone, interim platybasia was demonstrated on follow-up MR images. Conclusions. A progressive spectrum of distinct Oc-C2 injuries can occur in young children; the tectorial membrane is a critical stabilizing ligamentous structure in the Oc-C2 complex; and tectorial membrane abnormalities may be identified by a C1-2:C2-3 ratio of greater than or equal to 2.5.
BACKGROUND AND PURPOSE: Postoperative MR imaging is routinely performed for staging of medulloblastoma because of frequent tumor dissemination along CSF pathways. The goals of this study were to: 1) determine the timing of disease occurrence and contrast-enhanced MR imaging features of disseminated medulloblastoma involving the spine and their relationship to patient outcomes; and 2) compare the diagnostic accuracy of MR imaging findings with CSF cytologic analysis. METHODS: Medical records, pathologic reports, and unenhanced and contrast-enhanced postoperative MR images of the spine and head from 112 patients who had resection of medulloblastoma were retrospectively reviewed. MR images of the spine were evaluated for abnormal contrast enhancement in the meninges and vertebral bone marrow. MR images of the head were evaluated for recurrent or residual intracranial tumor. Imaging data were correlated with available CSF cytologic results and patient outcomes. RESULTS: Twelve patients (11%) had tumor within the spinal leptomeninges depicted on MR images at the time of diagnosis. Twenty-five patients (22%) had disseminated disease in the spine (leptomeninges, n = 22; vertebral marrow, n = 1; or both locations, n = 2) on MR images 2 months to 5.5 years (mean, 2 years) after initial surgery and earlier negative imaging examinations. Eleven other patients (10%) had recurrent intracranial medulloblastoma without spinal involvement seen with MR imaging. Spinal MR imaging had a sensitivity of 83% in the detection of disseminated tumor, whereas contemporaneous CSF cytologic analysis had a sensitivity of 60%. The sensitivity of CSF cytologic analysis increased to 78% with acquisition of multiple subsequent samples, although diagnosis would have been delayed by more than 6 months compared with diagnosis by spinal MR imaging in six patients. Spinal MR imaging was found to have greater overall diagnostic accuracy than CSF cytologic analysis in the early detection of disseminated tumor (P = .03). Spinal MR imaging confirmed disseminated tumor when contemporaneous CSF cytologic findings were negative in 13 patients, whereas the opposite situation occurred in only two patients. False-positive results for spinal MR imaging and CSF cytologic analysis occurred when these examinations were obtained earlier than 2 weeks after surgery. The 5-year survival probability for patients with spinal tumor was 0.24 +/- 0.08 versus 0.68 +/- 0.05 for the entire study group. CONCLUSION: Spinal MR imaging was found to have greater diagnostic accuracy than CSF cytologic analysis in the early detection of disseminated medulloblastoma. CSF cytologic analysis infrequently confirmed disseminated tumor when spinal MR imaging results were negative. Delaying spinal MR imaging and CSF cytologic analysis by more than 2 weeks after surgery can reduce false-positive results for both methods. The presence of disseminated medulloblastoma in the spine seen with MR imaging is associated with a poor prognosis.
Stroke in children is thought to be a rare phenomenon, but in a pediatric hospital, it is much more common than is expected. The development of rapid MRI imaging with diffusion techniques and MR spectroscopy has brought to the attention of both the neuroradiologists and clinicians that pediatric infarction, in both detection and management, are challenges for the future. Since 1995, cerebral diffusion has been performed at The Children's Hospital of Philadelphia in the evaluation of patients with acute cerebral compromise. Diffusion imaging looks at the motion of water molecules both intra- and extracellular, and the manner in which they become restricted in their motion when higher gradient strength is applied during the imaging sequence. Restricted diffusion is seen in cytotoxic edema, an early acute manifestation of ischemia/infarction. Diffusion studies are often positive when routine MRI and CT are as yet negative. Confirmation of the death of tissue is provided on proton spectroscopy by a rise in lactate from anaerobic glycolysis and a loss of N-acetylaspartate from neuronal death. Confirmation of the diffusion image findings, by mapping the apparent co-efficient (ADC), is also valuable. Application of these techniques, together with magnetic resonance angiography and magnetic resonance venography, is the substance of this paper.
We report MRI findings of a pathologically proven primary sarcoid granuloma of chiasmal origin that mimicked an optic pathway glioma
Explore the source record for details and available documents.
We studied the changes in brain water diffusion in childhood as seen on diffusion-weighted MRI in 30 children from 1 day of life to 17 years to provide a data base and to investigate the correlation of diffusion changes with known patterns of white matter maturation. The apparent diffusion coefficient (ADC) and apparent anisotropy (AA) were calculated in numerous regions of the brain to include major white matter tracts and gray matter. ADC and AA values were directly related to the structural maturity and compactness of the white matter tracts and changed with aging in a way that predated early myelination markers such as signal change on T1- or T2-weighted images. Diffusion of water is sensitive to structural changes in the brain such as white matter maturation and may be useful in investigating white matter disorders.
The last century has seen the evolution of neuroimaging from nonexistent to a group of techniques that, in our eyes, appears to be highly sophisticated. The rapidity of advancement in imaging has been concentrated in the last quarter century. There is no reason to expect this continual forward expansion of neuroradiology to abate; rather it seems likely that it will continue to increase at an even faster rate. The near future is one of refinement in imaging, faster and higher resolution as well as a much greater emphasis on physiology and biochemistry.
The Na+/myo-inositol cotransporter (SLC5A3) gene, located on the long arm of human chromosome 21, may play a key role in osmoregulation including the regulation of levels of the "idiogenic osmole," myo-inositol, in brain cells. To determine whether the levels of myo-inositol are increased in the basal ganglia of children with Down syndrome, we performed in vivo brain hydrogen 1-nuclear magnetic resonance or 1H-magnetic resonance spectroscopy and measured plasma osmolality in a cohort of children with trisomy 21. Myo-inositol is elevated in the corpus striatum of infants and children with Down syndrome, even in the absence of hypertonic stress.
This article reviews the complex anatomic relationships between structures in the sellar and parasellar regions. Normal anatomy and the normal imaging spectrum are reviewed, with emphasis on the diversity of pathology that originates from this region. Both CT and MR imaging may be used to evaluate the sellar and parasellar regions. This article discusses how modern imaging techniques enable characterization of the many lesions that alter the structure and function of normal sellar and parasellar anatomy.
BACKGROUND: Silent infarcts have been reported in 17% of young patients with sickle cell disease and are associated with impaired performance on standardized psychometric tests. Risk factors for the development of these lesions have not been identified. METHODS: Investigators in the Cooperative Study of Sickle Cell Disease performed a brain magnetic resonance imaging scan on sickle cell anemia patients age 5.9 years and older who had been followed according to the protocols of the Cooperative Study since birth. Individuals with a known history of cerebrovascular accident were excluded from this analysis. Patients with and without silent infarctions were compared with regard to clinical and laboratory parameters. RESULTS: The study sample included 42 patients (18.3%) with silent infarcts. Patients who had silent infarcts were significantly more likely to have a clinical history of seizure and a lower painful event rate. Lower hemoglobin level, increased leukocyte count, elevated pocked red blood cell count, and SEN betaS globin gene haplotype were associated also with the presence of silent infarcts. There was no relationship between silent infarcts and platelet count, fetal hemoglobin level, reticulocyte percentage, serum aspartate aminotransferase level, total bilirubin concentration, blood pressure, growth parameters, or presence of alpha-thalassemia. A multivariate model for silent infarction identified the following as risk factors: low pain event rate, history of seizure, leukocyte count >/=11.8 x 10(9)/L, and the SEN betaS globin gene haplotype. CONCLUSIONS: Patients with risk factors for silent infarcts should be evaluated for cerebrovascular disease. If evidence of infarction is found, consideration must be given to therapeutic intervention. At present, the appropriate treatment has not been determined.