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Background and Purpose: Pediatric brain tumors have diverse pathologic features, which poses diagnostic challenges. Although perfusion evaluation of adult tumors is well established, hemodynamic properties are not well characterized in children. Our goal was to apply arterial spin-labeling perfusion for various pathologic types of pediatric brain tumors and evaluate the role of arterial spin-labeling in the prediction of tumor grade., Materials and Methods: Arterial spin-labeling perfusion of 54 children (mean age, 7.5 years; 33 boys and 21 girls) with treatment-naive brain tumors was retrospectively evaluated. The 3D pseudocontinuous spin-echo arterial spin-labeling technique was acquired at 3T MR imaging. Maximal relative tumor blood flow was obtained by use of the ROI method and was compared with tumor histologic features and grade., Results: Tumors consisted of astrocytic (20), embryonal (11), ependymal (3), mixed neuronal-glial (8), choroid plexus (5), craniopharyngioma (4), and other pathologic types (3). The maximal relative tumor blood flow of high-grade tumors (grades III and IV) was significantly higher than that of low-grade tumors (grades I and II) (P < .001). There was a wider relative tumor blood flow range among high-grade tumors (2.14 ± 1.78) compared with low-grade tumors (0.60 ± 0.29) (P < .001). Across the cohort, relative tumor blood flow did not distinguish individual histology; however, among posterior fossa tumors, relative tumor blood flow was significantly higher for medulloblastoma compared with pilocytic astrocytoma (P = .014)., Conclusions: Characteristic arterial spin-labeling perfusion patterns were seen among diverse pathologic types of brain tumors in children. Arterial spin-labeling perfusion can be used to distinguish high-grade and low-grade tumors.

Background and Purpose: 2D gradient-echo imaging is sensitive to T2* lesions (hemorrhages, mineralization, and vascular lesions), and susceptibility-weighted imaging is even more sensitive, but at the cost of additional scan time (SWI: 5-10 minutes; 2D gradient-echo: 2 minutes). The long acquisition time of SWI may pose challenges in motion-prone patients. We hypothesized that 2D SWI/phase unwrapped images processed from 2D gradient-echo imaging could improve T2* lesion detection., Materials and Methods: 2D gradient-echo brain images of 50 consecutive pediatric patients (mean age, 8 years) acquired at 3T were retrospectively processed to generate 2D SWI/phase unwrapped images. The 2D gradient-echo and 2D SWI/phase unwrapped images were compared for various imaging parameters and were scored in a blinded fashion., Results: Of 50 patients, 2D gradient-echo imaging detected T2* lesions in 29 patients and had normal findings in 21 patients. 2D SWI was more sensitive than standard 2D gradient-echo imaging in detecting T2* lesions (P < .0001). 2D SWI/phase unwrapped imaging also improved delineation of normal venous structures and nonpathologic calcifications and helped distinguish calcifications from hemorrhage. A few pitfalls of 2D SWI/phase unwrapped imaging were noted, including worsened motion and dental artifacts and challenges in detecting T2* lesions adjacent to calvaria or robust deoxygenated veins., Conclusions: 2D SWI and associated phase unwrapped images processed from standard 2D gradient-echo images were more sensitive in detecting T2* lesions and delineating normal venous structures and nonpathologic mineralization, and they also helped distinguish calcification at no additional scan time. SWI processing of 2D gradient-echo images may be a useful adjunct in cases in which longer scan times of 3D SWI are difficult to implement.

Background and Purpose: Neurofibromatosis type 1 is associated with increased risk for stroke, cerebral vasculopathy, and neurocognitive deficits, but underlying hemodynamic changes in asymptomatic children remain poorly understood. We hypothesized that children with neurofibromatosis type 1 have decreased cerebral blood flow., Materials and Methods: Arterial spin-labeled CBF was measured in 14 children with neurofibromatosis type 1 (median age, 9.7 years; mean, 10.2 years; range, 22 months to 18 years) and compared with age-matched control subjects on 3T MR imaging. Three-dimensional pseudocontinuous spin-echo arterial spin-labeled technique was used. Measurements were obtained at cortical gray matter of bilateral cerebral hemispheres and centrum semiovale by use of the ROI method. Comparison by Mann-Whitney test was used, with Bonferroni-adjusted P values ≤.004 judged as significant., Results: We identified 7 of 12 areas with significantly diminished arterial spin-labeled CBF in patients with neurofibromatosis type 1 compared with control subjects. These areas included the anterior cingulate gyrus (P = .001), medial frontal cortex (P = .004), centrum semiovale (P = .004), temporo-occipital cortex (P = .002), thalamus (P = .001), posterior cingulate gyrus (P = .002), and occipital cortex (P = .001). Among patients with neurofibromatosis type 1, there were no significant differences in these regions on the basis of the presence of neurofibromatosis type 1 spots or neurocognitive deficits., Conclusions: Reduced cerebral perfusion was seen in children with neurofibromatosis type 1, particularly in the posterior circulation and the vascular borderzones of the middle and posterior cerebral arteries.

Background and Purpose: RS-EPI has been suggested as an alternative approach to EPI for high-resolution DWI with reduced distortions. To determine whether RS-EPI is a useful approach for routine clinical use, we implemented GRAPPA-accelerated RS-EPI DWI at our pediatric hospital and graded the images alongside standard accelerated (ASSET) EPI DWI used routinely for clinical studies., Materials and Methods: GRAPPA-accelerated RS-EPI DWIs and ASSET EPI DWIs were acquired on 35 pediatric patients using a 3T system in 35 pediatric patients. The images were graded alongside each other by using a 7-point Likert scale as follows: 1, nondiagnostic; 2, poor; 3, acceptable; 4, standard; 5, above average; 6, good; and 7, outstanding., Results: The following were the average scores for EPI and RS-EPI, respectively: resolution, 3.5/5.2; distortion level, 2.9/6.0; SNR, 3.4/4.1; lesion conspicuity, 3.3/5.9; and diagnostic confidence, 3.2/6.0. Overall, the RS-EPI had significantly improved diagnostic confidence and more reliably defined the extent and structure of several lesions. Although ASSET EPI scans had better SNR per scanning time, the higher spatial resolution as well as reduced blurring and distortions on RS-EPI scans helped to better reveal important anatomic details at the cortical-subcortical levels, brain stem, temporal and inferior frontal lobes, skull base, sinonasal cavity, cranial nerves, and orbits., Conclusions: This work shows the importance of both resolution and decreased distortions in the clinics, which can be accomplished by a combination of parallel imaging and alternative k-space trajectories such as RS-EPI.

Summary: HPE is a congenital brain malformation characterized by failure of the prosencephalon to divide into 2 hemispheres. We have identified 7 patients who have a mild subtype of HPE in which the midline fusion was restricted to the septal region or preoptic region of the telencephalon. This subtype, which we call septopreoptic HPE, falls in the spectrum of lobar HPE, but lacks significant frontal neocortical fusion seen in lobar HPE. Other imaging characteristics include thickened or dysplastic fornix, absent or hypoplastic anterior CC, and single unpaired ACA. The SP was fully formed in 4, partially formed in 2, and absent in 1. Mild midline craniofacial malformation, such as SMMCI and CNPAS were found in 86% and 71%, respectively. Patients outside of infancy often manifested language delay, learning disabilities, or behavioral disturbances, while motor function was relatively spared.

We present a case of congenital salivary gland anlage tumor (SGAT) of the nasal septum in a 2-week-old infant who had difficulty breathing through her nose since birth. CT and MR imaging demonstrated a circumscribed mass within the nasal cavity that did not communicate with the intracranial compartment. Differential diagnosis and clinical significance of recognizing this rare lesion are reviewed.

Background and Purpose: Subclinical cerebral edema occurs in many, if not most, children with diabetic ketoacidosis (DKA) and may be an indicator of subtle brain injury. Brain ratios of N-acetylaspartate (NAA) to creatine (Cr), measured by proton MR spectroscopy, decrease with neuronal injury or dysfunction. We hypothesized that brain NAA/Cr ratios may be decreased in children in DKA, indicating subtle neuronal injury., Materials and Methods: Twenty-nine children with DKA underwent cerebral proton MR spectroscopy during DKA treatment (2-12 hours after initiating therapy) and after recovery from the episode (72 hours or more after the initiation of therapy). We measured peak heights of NAA, Cr, and choline (Cho) in 3 locations within the brain: the occipital gray matter, the basal ganglia, and periaqueductal gray matter. These regions were identified in previous studies as areas at greater risk for neurologic injury in DKA-related cerebral edema. We calculated the ratios of NAA/Cr and Cho/Cr and compared these ratios during the acute illness and recovery periods., Results: In the basal ganglia, the ratio of NAA/Cr was significantly lower during DKA treatment compared with that after recovery (1.68 +/- 0.24 versus 1.86 +/- 0.28, P<.005). There was a trend toward lower NAA/Cr ratios during DKA treatment in the periaqueductal gray matter (1.66 +/- 0.38 versus 1.91 +/- 0.50, P=.06) and the occipital gray matter (1.97 +/- 0.28 versus 2.13 +/- 0.18, P=.08). In contrast, there were no significant changes in Cho/Cr ratios in any region., Conclusions: NAA/Cr ratios are decreased in children during DKA and improve after recovery. This finding suggests that during DKA neuronal function or viability or both are compromised and improve after treatment and recovery.

Background and Purpose: Ketone bodies provide important alternate fuel for brain metabolism, and their transport into the brain increases with prolonged fasting. During diabetic ketoacidosis (DKA), serum ketone concentrations markedly increase; however, little is known about whether ketone bodies accumulate in cerebral tissues during DKA. We used proton MR spectroscopy (MRS) to detect cerebral beta-hydroxy butyrate (betaOHB) and acetone/acetocaetate (AcAc) in children with DKA., Methods: Twenty-five children underwent brain MRS: nine within 4 hours of the start of treatment for DKA; 11, at 4-8 hours; and five, at 8-12 hours. MRS was repeated after their recovery from the DKA episode at > or =72 hours after the start of treatment. MRS was evaluated for peaks corresponding to betaOHB (doublet centered on 1.20 ppm) and lactate (doublet centered on 1.33 ppm). Difference spectroscopy was used to identify the AcAc peak at 2.22-2.26 ppm., Results: betaOHB was detected in 13 children (52%), more frequently within 4 hours (eight children, 89%) than after 4 hours (five children, 31%). AcAc was detected in 15 children (60%), more frequently at >4 hours after the start of treatment (12 patients, 75%) than in the first 4 hours (three patients, 33%). Lactate was detected in five children (18%), all within the first 8 hours of treatment., Conclusion: In children, betaOHB and AcAc accumulate in the brain during DKA, and they can be detected on MRS. Care should be taken in interpreting MRS results in patients with DKA to avoid erroneously attributing betaOHB peaks to lactate.

Background and Purpose: Low birth weight preterm infants are at high risk of brain injury, particularly injury to the white matter. Diffusion tensor imaging is thought to be more sensitive than conventional MR imaging for detecting subtle white matter abnormalities. The objective of this study was to examine whether diffusion tensor imaging could detect abnormalities that may be associated with later neurologic abnormalities in infants with otherwise normal or minimally abnormal conventional MR imaging findings., Methods: We prospectively studied 137 low birth weight (<1800 g) preterm infants. Neonatal conventional MR imaging and diffusion tensor imaging were performed near term-equivalent age before discharge, and neurologic development of the infants was later followed up at 18 to 24 months of age., Results: Among the preterm infants who were fully studied, 63 underwent normal conventional MR imaging. Three of these infants developed cerebral palsy, and 10 others showed abnormal neurologic outcome. Diffusion tensor imaging results for these infants showed a significant reduction of fractional anisotropy in the posterior limb of the internal capsule in neurologically abnormal infants (including those with cerebral palsy) compared with control preterm infants with normal neurologic outcomes., Conclusion: These results suggest that neonatal diffusion tensor imaging may allow earlier detection of specific anatomic findings of microstructural abnormalities in infants at risk for neurologic abnormalities and disability. The combination of conventional MR imaging and diffusion tensor imaging may increase the predictive value of neonatal MR imaging for later neurologic outcome abnormalities and may become the basis for future interventional clinical studies to improve outcomes.

Background and Purpose: Jugular foraminal stenosis (JFS) or atresia (JFA) with collateral emissary veins (EV) has been documented in syndromic craniosynostosis. Disruption of EV during surgery can produce massive hemorrhage. Our purpose was to describe the prevalence of prominent basal emissary foramina (EF), which transmit enlarged EV, in syndromic craniosynostosis. Our findings were correlated with phenotypic and molecular diagnoses., Methods: We reviewed the medical records and imaging examinations of 33 patients with syndromic craniosynostosis and known fibroblast growth factor receptor (FGFR) mutations. All patients underwent CT and 14 MR imaging. The cranial base was assessed for size of occipitomastoid EF and jugular foramina (JF). Vascular imaging studies were available from 12 patients. A control group (n = 76) was used to establish normal size criteria for JF and EF., Results: Phenotypic classification included Crouzon syndrome (n = 10), crouzonoid features with acanthosis nigricans (n = 3), Apert syndrome (n = 10), Pfeiffer syndrome (n = 4), and clinically unclassifiable bilateral coronal synostosis (n = 6). EF > or = 3 mm in diameter and JFS or JFA were identified in 23 patients with various molecular diagnoses. Vascular imaging in patients with JFS or JFA and enlarged EF revealed atresia or stenosis of the jugular veins and enlarged basal EV. JFA was seen in all patients with the FGFR3 mutation with crouzonoid features and acanthosis nigricans. Four patients had prominent EF without JFS. Six patients had normal JF and lacked enlarged EF., Conclusion: Enlarged basal EF are common in syndromic craniosynostosis and are usually associated with JFS or JFA. Bilateral basilar venous atresia is most common in patients with the FGFR3 ala391glu mutation and crouzonoid features with acanthosis nigricans, but may be found in patients with FGFR2 mutations. Skull base vascular imaging should be obtained in patients with syndromic craniosynostosis with enlarged EF.

Diffusion imaging has been widely used in the brain, but its application in the spinal cord has been limited. Using line-scan diffusion imaging (LSDI), a technique that is less sensitive to magnetic susceptibility and motion artifacts than are other diffusion techniques, we have successfully imaged the spinal cord in children. The apparent diffusion coefficient and relative diffusion anisotropy of the normal spinal cord were measured. LSDI was compared with echo-planar diffusion imaging of the spine in three patients.

A three-dimensional image registration technique for CT and MR studies of the cervical spine was evaluated for feasibility and efficacy. Registration by means of external fiducial markers was slightly more accurate than registration by anatomic landmarks. The interrelationships between bony (eg, neural foramina) and soft tissue structures (eg, nerve roots) in the cervical spine were more conspicuous on registered images than on conventional displays. Registration of CT and MR images may be used to examine more precisely the relationships between bony and soft tissue structures of the cervical spine.

Background and Purpose: Infections caused by nontuberculous mycobacteria (NTM) commonly manifest as cervicofacial adenitis in otherwise healthy children. The aim of this study was to characterize the imaging findings of NTM infection of the head and neck in immunocompetent children., Methods: The medical records and imaging examinations (CT in 10, MR in two) were reviewed in 12 immunocompetent children with NTM infection of the head and neck., Results: The usual presentation (n = 9) was of an enlarging, non-tender mass with violaceous skin discoloration, unresponsive to conventional antibiotics. The duration of symptoms was 6 days to 5 months. Imaging revealed asymmetric adenopathy with contiguous low-density ring-enhancing masses in all patients. There was cutaneous extension in 10 patients. Inflammatory stranding of the subcutaneous fat was minimal (n = 9) or absent (n = 2) in 11 patients. The masses involved the submandibular space (n = 3), the parotid space (n = 2), the cheek (n = 1), the anterior triangle of the neck (n = 2), the submandibular and parotid spaces (n = 2), the parotid space and neck (n = 1), and the neck and retropharyngeal space (n = 1). Surgical management included incision and drainage only (n = 2), incision and drainage with curettage (n = 2), excisional biopsy after incision and drainage (n = 1), excisional biopsy only (n = 5), superficial parotidectomy only (n = 1), and superficial parotidectomy with contralateral excisional biopsy (n = 1). All patients improved in response to surgery and long-term antimycobacterial antibiotics., Conclusion: NTM infection of the head and neck has a characteristic clinical presentation and imaging appearance. Recognition of this disease is important; appropriate treatment is excision and, in selected cases, antimycobacterial therapy.

Background and Purpose: MR diffusion-weighted imaging provides early demonstration of neonatal brain infarction. The evolution and limitations of diffusion-weighted imaging findings in newborns, however, have not been evaluated. Using line-scan diffusion imaging (LSDI), we investigated perinatal ischemic brain injury., Methods: Nineteen term newborns (age, 9 hours to 8 days; mean age, 2.6 days) with perinatal brain ischemia were evaluated using LSDI (1520/62.5/1 [TR/TE/excitations]) (b maximum = 750 s/mm2) and T1- and T2-weighted spin-echo (conventional) MR imaging. Follow-up examinations were performed in seven patients and autopsy in one. Apparent diffusion coefficients (ADCs) were measured in deep gray matter, white matter, the cortex, and focal lesions., Results: Based on conventional MR imaging or pathologic findings, patients were divided into two groups. Group 1 (n = 12) had symmetric/diffuse injury consistent with global hypoperfusion. Group 2 (n = 7) had focal/multifocal injury suggesting cerebrovascular occlusion. ADCs were abnormal at initial examination in 10 newborns in group 1 and in all newborns in group 2. The results of LSDI were abnormal before conventional MR imaging was performed in three newborns in group 1. ADCs were maximally decreased between days 1 and 3 in deep gray matter, perirolandic white matter, and focal lesions. Delayed decreases in ADCs were observed in subcortical white matter from days 4 through 10 in three patients in group 1., Conclusion: After global hypoperfusion, LSDI showed deep gray matter and perirolandic white matter lesions before conventional MR imaging. LSDI may underestimate the extent of injury, however, possibly because of variations in the compartmentalization of edema, selective vulnerability, and delayed cell death. Differences in LSDI of symmetric/diffuse and focal/multifocal lesions may reflect differences in pathophysiology or timing of the injury. These findings may have implications for acute interventions.

Background and Purpose: MR imaging of the self-diffusion of water has become increasingly popular for the early detection of cerebral infarction in adults. The purpose of this study was to evaluate MR line scan diffusion imaging (LSDI) of the brain in children., Methods: LSDI was performed in four volunteers and 12 patients by using an effective TR/TE of 2736/89.4 and a maximum b value of 450 to 600 s/mm2 applied in the x, y, and z directions. In the volunteers, single-shot echo planar imaging of diffusion (EPID) was also performed. The patients (10 boys and two girls) ranged in age from 2 days to 16 years (average age, 6.6 years). Diagnoses included acute cerebral infarction, seizure disorder, posttraumatic confusion syndrome, complicated migraine, residual astrocytoma, encephalitis, hypoxia without cerebral infarction, cerebral contusion, and conversion disorder. In all patients, routine spin-echo images were also acquired. Trace images and apparent diffusion coefficient maps were produced for each location scanned with LSDI., Results: In the volunteers, LSDI showed less chemical-shift and magnetic-susceptibility artifact and less geometric distortion than did EPID. LSDI was of diagnostic quality in all studies. Diffusion abnormalities were present in five patients. Restricted diffusion was present in the lesions of the three patients with acute cerebral infarction. Mildly increased diffusion was present in the lesions of encephalitis and residual cerebellar astrocytoma. No diffusion abnormalities were seen in the remaining seven children., Conclusion: LSDI is feasible in children, provides high-quality diffusion images with less chemical-shift and magnetic-susceptibility artifact and less geometric distortion than does EPID, and complements the routine MR examination.

Purpose: This study was done to determine which clinical and imaging findings best correlate with outcome in children with tectal tumors., Methods: A retrospective review was done of the medical records and imaging studies of 32 children (16 boys and 16 girls; mean age, 8 years) with tectal tumors. Eight children had CT, 11 had MR imaging, and 13 had both CT and MR studies. Findings from surgical and pathologic reports as well as from follow-up examinations (mean follow-up period, 5 years; range, 3.6 months to 17 years) were included in the review., Results: All patients had hydrocephalus and all but one required CSF diversion. The tectum was the center of the tumor in all cases and the majority of the tumors appeared isodense on CT scans, isointense on T1-weighted MR images, and hyperintense on T2-weighted images. Twenty patients required no further treatment. In this group, the mean maximum tumor diameter was 1.8 cm and enhancement occurred in two cases. At follow-up, 18 patients had stable tumor size, one had an increase in tumor size with cyst formation but no worsening of symptoms, and one had a decrease in tumor size. Twelve patients required further treatment (excision and/or radiotherapy) because of progression as indicated by either increased tumor size or worsening of symptoms. In this group, the mean maximum tumor diameter was 2.5 cm and contrast enhancement occurred in nine cases. Further follow-up in this group showed decreased tumor size in eight and stable residual tumor in three., Conclusion: Tectal tumors in childhood have variable behavior. MR imaging assists in the clinical determination of which children need treatment beyond CSF diversion. Larger tumor size and enhancement are radiologic predictors of the need for further treatment.

Purpose: Our purpose was to determine the sensitivity, specificity, and receiver operator characteristic (ROC) curve of a fast screening MR protocol in children and adolescents with suspected intracranial tumors., Methods: One hundred forty-one patients (mean age, 9.7 years; range, 2 months to 23.5 years) with suspected brain tumor were entered in a case-control study. Eighty-seven patients had intracranial tumors (31 suprasellar/hypothalamic, 27 supratentorial, 26 infratentorial, and three pineal) and 54 patients in the control group had other disorders. Two neuroradiologists reviewed blindly a detailed three-sequence conventional protocol (acquisition time, 8 minutes 27 seconds) and a two-sequence fast screening MR protocol (acquisition time, 4 minutes 44 seconds)., Results: Sensitivity and specificity of the fast screening protocol for intracranial tumors was 100% and 92.6%, respectively. The areas under the ROC curves were 0.966 for the fast screening and 0.980 for the conventional MR protocol. No diagnostic performance difference was found between the ROC curves using the Az index. A kappa statistic of .93 for both examinations indicated excellent interobserver agreement. Additional MR sequences and other neuroimaging studies were not deemed necessary to exclude the presence of an intracranial tumor., Conclusion: A fast dual-plane brain MR protocol may be adequate to screen children and adolescents thought to have an intracranial tumor. The less than 5 minute acquisition time allows a complete examination (including preparation) to be performed in 10 to 15 minutes. Future studies are recommended before this time-efficient neuroimaging examination is incorporated into clinical practice.

Purpose: To emphasize the importance of imaging in children with diencephalic syndrome due to hypothalamic/chiasmatic astrocytomas., Methods: Findings in nine patients (mean age, 26 months) with diencephalic syndrome and hypothalamic/chiasmatic astrocytomas were analyzed retrospectively, including reviewing clinical records, imaging examinations, and follow-up studies., Results: Symptoms and signs included failure to thrive (n = 9), nystagmus (n = 3), visual field defects (n = 1), optic pallor (n = 1), emesis (n = 2), and headache (n = 1). All patients had hypothalamic/chiasmatic masses. Five patients underwent biopsy, and, in all cases, specimens showed low-grade astrocytoma. Imaging studies were available in eight patients. All tumors were large (median maximum diameter, 3.5 cm), involved the chiasm and hypothalamus, and showed homogeneous enhancement. Three patients had hydrocephalus and two had metastases. At follow-up, five patients had recurrent disease and two had died., Conclusion: Diencephalic syndrome is a rare cause of failure to thrive in childhood, and diagnosis of a hypothalamic/ chiasmatic astrocytoma might therefore be delayed. The astrocytomas associated with this syndrome are larger, occur at a younger age, and are often more aggressive than other astrocytomas arising in this region.

Purpose: To describe the angiographic changes accompanying the surgical treatment of moyamoya disease by pial synangiosis and to compare these changes with patient outcome., Methods: The preoperative and postoperative cerebral angiograms, MR images, and clinical records of 13 children treated with pial synangiosis for moyamoya disease were reviewed., Results: After synangiosis, 10 patients had significant neurologic improvement and three had minimal or no improvement. Postoperative MR images showed no new infarctions. Well-developed (grade A or B) transpial or transdural collaterals to the brain were present at the site of synangiosis in 84% of the surgically treated hemispheres. Cerebrovascular occlusive changes increased postoperatively in 76% of hemispheres. After synangiosis, moyamoya collaterals were increased in 48%, unchanged in 16%, and decreased in 36% of surgically treated hemispheres. All 10 patients with grade A or B collaterals bilaterally after synangiosis were asymptomatic or improved on follow-up., Conclusion: Pial synangiosis typically results in an increase in collaterals from the superficial temporal artery or middle meningeal artery to the brain. Synangiosis appears to result in stabilization or improvement in neurologic symptoms but does not prevent the angiographic progression of disease or the development of moyamoya collaterals. The angiographic demonstration of well-formed collaterals after synangiosis is associated with a favorable clinical outcome.

Purpose: To assess multivoxel proton MR spectroscopy combined with MR imaging and hemodynamic MR imaging in the evaluation of brain tumors in children and young adults., Methods: Fifteen patients with brain tumors and 10 healthy children underwent MR imaging and MR spectroscopy on a 1.5-T system. Ten patients with tumors had both MR spectroscopy and hemodynamic MR imaging. MR spectroscopy data sets with 1 cm3 to 3.4 cm3 resolution were acquired within 8.5 minutes by using a point-resolved spectroscopic, chemical-shift imaging technique in two dimensions with volume preselection. MR imaging was performed using fast spin-echo techniques. Hemodynamic MR imaging data were acquired every 2.5 seconds at one anatomic level using a spoiled gradient-echo sequence during intravenous bolus administration of contrast material., Results: Assessment with multivoxel MR spectroscopy and hemodynamic MR imaging added about 30 minutes to the total MR examination time. Normal tissue exhibited spectral peaks from biologically significant compounds such as N-acetylaspartate (NAA), choline-containing compounds (Cho), and total creatine (tCr). Twelve biopsy-proved tumors exhibited prominent Cho, reduced NAA, variable tCr, and/or lactate or lipids, and two showed increased hemodynamic parameters. Three of the tumors treated with radiation did not reveal prominent levels of Cho. Tissue necrosis had no Cho, NAA, or tCr, and reduced hemodynamics., Conclusions: Preliminary findings by MR spectroscopy combined with MR imaging and hemodynamic MR imaging suggest that regions of active tumor may be differentiated from areas of normal tissue and areas of necrosis. These findings may enable metabolic and hemodynamic characterization of childhood brain tumors as well as suggest their response to therapy.

Purpose: To review the clinical and MR imaging findings in adolescents with hemorrhagic pituitary adenomas and to compare those findings with pathologic results and outcome., Methods: We reviewed the clinical records, imaging examinations, surgical and pathologic findings, and follow-up studies in 11 girls and six boys (12 to 20 years old; mean age, 16 years) with pituitary adenomas who were treated at our institution between August 1986 and June 1995., Results: Of the 17 adenomas, eight were macroadenomas (> 1 cm) in patients 14 to 18 years old (three girls, five boys). Six of the macroadenomas were grossly hemorrhagic, and appeared as high-intensity intrasellar/suprasellar masses on all MR sequences obtained before definitive diagnosis and treatment. Clinical presentation in the patients with the hemorrhagic macroadenomas included headache (five), visual field deficits (three), and neuroendocrine symptoms (three). One patient was asymptomatic. The preliminary clinical and imaging diagnoses were craniopharyngioma or Rathke's cyst in five of the six cases. Pathologic diagnoses were prolactinoma in four patients, plurihormonal (prolactin/follicle-stimulating hormone) tumor in one patient, and nonfunctioning adenoma in one patient. Surgical resection was performed in all six hemorrhagic tumors and radiation therapy was required in three cases., Conclusion: Pituitary adenomas uncommonly occur in childhood and are usually seen in adolescence. The majority of the macroadenomas are hemorrhagic and often occur in male subjects. The clinical and MR imaging features may mimic craniopharyngioma or Rathke's cyst. These tumors often require surgery and/or radiation therapy.

Purpose: To review the clinical data, imaging findings, and intermediate outcomes of a series of children with hemorrhagic vasculopathy after treatment for intracranial neoplasia., Methods: We retrospectively analyzed the medical records and imaging examinations of 20 pediatric patients (ages 1 to 15 years) with intracranial neoplasia in whom delayed intracranial hemorrhage developed after cranial irradiation or radiation combined with systemic or intrathecal chemotherapy. Patients with intracranial hemorrhage from other identifiable causes were excluded. Histopathologic analysis was available in four patients., Results: Twenty patients with delayed intracranial hemorrhage received cranial irradiation alone (n = 9) or combined radiation and chemotherapy (n = 11) for primary brain tumors (n = 13), leukemia (n = 6), or lymphoma (n = 1). Imaging findings were consistent with hemorrhages of varying ages. The hemorrhages were not associated with tumor recurrence nor second tumors. Except for location of the hemorrhage, no significant relationship was established between outcome and original diagnosis, radiation dose (range, 1800 to 6000 centigray), chemotherapeutic agent or dosage, age at treatment, or interval between therapy and hemorrhage (mean, 8.1 years). Only brain stem hemorrhage was associated with a poor outcome., Conclusion: In children with central nervous system neoplasia who have undergone cranial irradiation, or radiation combined with chemotherapy, delayed intracranial hemorrhage may develop.

Purpose: To review the clinical and imaging findings in pediatric and adolescent intracranial pure oligodendrogliomas., Methods: The clinical, CT, and MR data in 39 surgically proved pure oligodendrogliomas were retrospectively reviewed., Results: The frontal or temporal lobes were involved in 32 (82%) cases. Seventy percent of the tumors were hypodense on CT, three-fourths were hypointense on T1-weighted images, and all were hyperintense on spin-density and T2-weighted images. Fewer than 40% of the lesions demonstrated calcification, and nearly 60% had well-defined margins. Mass effect was seen in fewer than half of the cases, and edema could be separately identified in only one case. Tumor enhancement was seen in fewer than 25%. In 39 cases after partial (3), subtotal (16), or total (20) resection, follow-up studies demonstrated stability over a mean period of 5 years., Conclusion: The findings in this pediatric series of pure oligodendrogliomas (without mixed cell elements) differ from previous adult series in that calcification, contrast enhancement, and edema are seen less frequently. In addition, very slow or no growth is often characteristic, and these patients have an excellent prognosis with surgical resection.

Purpose: To evaluate diagnostic reliability and to establish optimal scanning techniques of a recently developed Fast Spin-echo MR pulse sequence that allows rapid proton density-weighted and T2-weighted imaging., Methods: We compared lesion conspicuity and signal intensity measurements on Fast Spin-echo and conventional spin-echo sequences in 81 patients ranging from 1 week to 25 years in age on a 1.5-T MR unit. A total of 28 Fast Spin-echo dual-echo images (14 slice locations) were obtained in 2:08 minutes with a 256 x 128 matrix or in 3:12 minutes with a 256 x 192 matrix at a TR of 2000 msec and two excitations., Results: Lesion conspicuity and characterization on Fast Spin-echo images compared favorably with conventional spin-echo images in our series when pseudo-TEs of 15 and 90 msec were employed for proton density-weighted and T2-weighted images, respectively. Fast Spin-echo images yielded diagnostic information in four nonsedated patients whose conventional spin-echo images were either degraded by motion or unobtainable. Fat signal remained bright on T2-weighted Fast Spin-echo images. Magnetic-susceptibility effects were slightly reduced with Fast Spin-echo but did not pose any diagnostic problem in our series., Conclusion: Diagnostically reliable rapid dual-echo brain images can be obtained with Fast Spin-echo sequences.

Eight infants with radiographic and bone biopsy evidence of autosomal recessive osteopetrosis were evaluated by cranial CT. The clinical presentations and CT characteristics support the theory that this disorder exhibits severe and mild variants. At an early stage the severe variant demonstrates small optic canals, small orbits with proptosis, and a small nasoethmoid complex without significant bone thickening. The paranasal sinuses show bud formation but no pneumatization. The temporal bone retains a fetal appearance with trumpet-shaped internal auditory canals, prominent subarcuate fossae, and no mastoid pneumatization. The ventricles and subarachnoid spaces are enlarged. Bone thickness increases with age, leading to further orbital encroachment. Similar but less severe features are present in the mild variant. Underdevelopment of the orbits, nasoethmoid complex, and temporal bone suggests that delayed maturation is the primary morphologic abnormality of the skull base in osteopetrosis, and that bone thickening is a secondary manifestation caused by reduced bone turnover.