Postcontrast T1-weighted Brain Magnetic Resonance Imaging in Pediatric Patients: Comparison Between Postcontrast Fat-suppression Imaging and Conventional T1-weighted or Magnetization Transfer Imaging

PURPOSE: We wished to assess the merits and weaknesses of postcontrast fat-suppression (FS) brain MR imaging in children for the evaluation of various enhancing lesions as compared with postcontrast conventional T1-weighted or magnetization transfer (MT) imaging. MATERIALS AND METHODS: We reviewed the records of those patients with enhancing lesions on brain MR imaging who had undergone both FS imaging and one of the conventional T1-weighted or MT imaging as a postcontrast T1-weighted brain MR imaging. Thirty-one patients (21 male, 10 female; mean age, 8.7 years) with 38 enhancing lesions (18 intra-axial, 16 extra-axial and 4 orbital locations) were included in this study. There were 27 pairs of FS and conventional imagings, and 13 pairs of FS and MT imagings available for evaluation. Two radiologists visually assessed by consensus the lesions' conspicuity, and they also looked for the presence of flow or susceptibility artifacts in a total of 40 pairs of MR imagings. For 19 measurable lesions (14 pairs of FS and conventional T1-weighted imagings, 5 pairs of FS and MT imagings), the contrast ratios between the lesion and the normal brain ([SIlesion-SIwater]/[SInormal brain-SIwater]) were calculated and compared. RESULTS: Compared with conventional imaging, the lesion conspicuity on FS imaging was better in 10 cases (7 extra-axial lesions, 2 orbital lesions and 1 fat-containing intra-axial lesion), equal in 16 cases, and worse in one case. Compared with MT imaging, the lesion conspicuity on FS imaging was better in 3 cases (2 extra-axial lesions and 1 intra-axial lesion), equal in 8 cases, and worse in 2 cases. Image quality of FS imaging was compromised by flow or susceptibility artifacts for 7 patients. The contrast ratios for FS imaging were not significantly different from those for conventional imaging (2.2+/-0.7 vs. 2.2+/-0.6, respectively, p=0.914) and they were significantly lower than those for MT imaging (2.4+/-0.8 vs. 4.5+/-1.5, respectively, p=0.018). CONCLUSION:Postcontrast FS brain MR imaging appears to be better than the conventional T1-weighted imaging and comparable to MT imaging for the visual assessment of enhancing lesions. Especially, the FS imaging has the merit to delineate orbital and extra-axial enhancing lesions or fat-containing lesions, whereas it is disadvantageous when flow or susceptibility artifacts occur.

Traumatic Intracranial Aneurysms in Children

PURPOSE: To describe the imaging findings of traumatic intracranial aneurysms (TICA) in children. MATERIALS AND METHODS: Five boys aged 3-15 (mean, 7) years with surgically confirmed TICA were included in this study. All had a history of nonpenetrating head trauma, and they underwent precontrast CT imaging immediately after the injury and follow-up CT or MRI. In all cases, angiography revealed the presence of aneurysms, which at surgery were shown to be pseudoaneurysms with severe adhesions. RESULTS: Angiography demonstrated that all aneurysms were located in the anterior cerebral artery (ACA) or its branches. The precise locations were the A2 segment of the ACA, the site of origin of the callosomarginal artery or its first branch, or of the anterior internal frontal artery, or between the first and second branch of the pericallosal artery. In all patients, precontrast CT performed immediately after trauma depicted subarachnoid hemorrhage (SAH) in the anterior interhemispheric fissure (AIHF). Follow-up precontrast CT showed nodular high density around the anterior falx in three, recurrent SAH in the AIHF in two, and intracerebral hemorrhage (ICH) with intraventricular hemorrhage in two. In two patients with a nodular high-density lesion, nodular enhancement was demonstrated at postcontrast CT, and in one, follow-up MRI revealed a nodular signal void around the anterior falx; nodular enhancement was seen at postcontrast imaging, and MR angiogram depicted a saccular aneurysm. In one patient, MRI demonstrated infarction in the caudate nucleus and ACA territory. CONCLUSION: If, after head injury, an area of nodular high density is revealed by CT, or a signal void by MRI, or if SAH or ICH is present around the anterior falx, the possibility of TICA should be considered.

MRI Finding of Ethylmalonic Encephalopathy: Case Report

Ethylmalonic encephalopathy is a rare syndrom characterized by developmental delay, acrocyanosis, petechiae, chronic diarrhea, and ethylmalonic, lactic, and methylsuccinic aciduria. We report the MRI finding of ethylmalonic encephalopathy including previously unreported intracranial hematoma.

Imaging Findings of Atypical Teratoid/Rhabdoid Tumor of Infancy & Childhood in CNS: Report of Two Cases

Atypical teratoid/rhabdoid tumor rarely occurs in the CNS, though is most common in infants under two years of age. It is characterized by unique histologic features, has an extremely aggressive natural course, and is located mainly in the infratentorial region. Radiologically, it is difficult to distinguish from primitive neuroectodermal tumor or medulloblastoma. We report the radiologic findings of two cases of atypical teratoid/rhabdoid tumor.

MR Imaging of Acute Necrotizing Encephalopathy:A Report of Two Cases

Acute necrotizing encephalopathy is the term used to describe acute encephalopathy with bilateral thalam-otegmental involvement that occurs in infants and children after febrile viral illness. We report the MR findings of two cases of this condition.

MR Imaging of Shaken Baby Syndrome Manifested as Chronic Subdural Hematoma

Shaken baby syndrome (SBS) is a form of child abuse that can cause significant head injuries, of which subdural hematoma (SDH) is the most common manifestation. We report the MRI findings of chronic SDH in three cases of SBS, involving two-, three- and eight-month-old babies. The SDH signal was mostly low on T1-weighted images and high on T2-weighted images, suggesting chronic SDH. In chronic SDH, a focal high signal on T1-weighted images was also noted, suggesting rebleeding. Contrast-enhanced MRI revealed diffuse dural enhancement.

Postoperative Meningeal Enhancement on MRI in Children with Brain Neoplasms

The meninges composed of the dura, the arachnoid and the pia are significant sites of blood-brain barrier. Physical disruption of the integrity of the meninges from avariety of causes including surgery results in various patterns of meningeal enhancement on contrast enhanced MR images. It is important to distinguish normal reactive or benign postoperative enhancement from more serious leptomeningeal metastasis or infection, particularly in children with intracranial neoplasms. We present various pat-terns of meningeal enhancement on MRI in children following surgery for brain neop lasms.

Imaging of the Ventriculoperitoneal Shunt-Related Complications in Infants and Children With Hydrocephalus

PURPOSE: To evaluate the frequency and imaging findings of various ventriculo-peritoneal shunt-relatedcomplications in pediatric patients with hydrocephalus. MATERIALS AND METHODS: We retrospectively reviewed 246plain radiographs, three shuntograms, 53 ultrasounds, 133 CT scans, and 24 MR images obtained before and after theventriculo-peritoneal shunt procedure in 33 pediatric patients with hydrocephalus. Using preoperative images, theetiology of the hydrocephalus was assessed. Changes in the size and shape of the ventricles, the location andcontinuity of shunt apparatus, and the presence of any abnormal enhancement, hemorrhage, edema or tissue loss, orother findings of complications, were analyzed on postoperative images; the frequency and imaging findings ofshunt-related complications such as shunt malfunction, infection, hemorrhage or isolated ventricle, andcomplications caused by overdrainage, were thus evaluated. The frequency of such complications was analyzedaccording to the etiology of the hydrocephalus, and in addition, medical records were reviewed and correlated withimaging findings. RESULTS: In 18 of the 33 patients(54%), a total of 31 complications was detected. These werepresent in four of five cases (80%) of hydrocephalus caused by meningitis and ventriculitis, seven of twelve (58%)intraventricular hemorrhage, two of four (50%) unknown cases, three of nine (33%) congenital malformations, one oftwo (50%) tumors, and one (100%) congenital infection. Shunt malfunction was most common(n=15), and wasaccompanied by findings of enlarged ventricles, periventricular and peritubal edema, and abnormal location of theshunt tube. Symptoms and signs of increased intracranial pressure were also noted. Subdural hemorrhage andinfection were present infour cases each;findings of infection were enhancement of the ventricular wall, meninges,and parenchyma, as well as sonographically noted intraventricular septation and increased ventricular wall echo.Isolated lateral ventricle (n=4) or 4th ventricle (n=1) was persistently distended in spite of the presence of ashunt tube within the other ventricle. Collapsed ventricles, thick calvarium, and symptoms of increasedintracranial pressure were helpful in the diagnosis of slit ventricle syndrome(n=1). Immediate postoperativeintraventricular and parenchymal hemorrhage were noted in one case each. CONCLUSION: Shunt-related complicationswere found on postoperative images in 54% of pediatric patients with hydrocephalus; the frequency was highest incases of hydrocephalus caused by infection. Shunt malfunction occurred most frequently and each complication hadvarious imaging findings. For the diagnosis of post-operative shunt-related complication, continuous follow-upstudies are therefore necessary.

Imaging of the Ventriculoperitoneal Shunt-Related Complications in Infants and Children With Hydrocephalus

PURPOSE: To evaluate the frequency and imaging findings of various ventriculo-peritoneal shunt-relatedcomplications in pediatric patients with hydrocephalus. MATERIALS AND METHODS: We retrospectively reviewed 246plain radiographs, three shuntograms, 53 ultrasounds, 133 CT scans, and 24 MR images obtained before and after theventriculo-peritoneal shunt procedure in 33 pediatric patients with hydrocephalus. Using preoperative images, theetiology of the hydrocephalus was assessed. Changes in the size and shape of the ventricles, the location andcontinuity of shunt apparatus, and the presence of any abnormal enhancement, hemorrhage, edema or tissue loss, orother findings of complications, were analyzed on postoperative images; the frequency and imaging findings ofshunt-related complications such as shunt malfunction, infection, hemorrhage or isolated ventricle, andcomplications caused by overdrainage, were thus evaluated. The frequency of such complications was analyzedaccording to the etiology of the hydrocephalus, and in addition, medical records were reviewed and correlated withimaging findings. RESULTS: In 18 of the 33 patients(54%), a total of 31 complications was detected. These werepresent in four of five cases (80%) of hydrocephalus caused by meningitis and ventriculitis, seven of twelve (58%)intraventricular hemorrhage, two of four (50%) unknown cases, three of nine (33%) congenital malformations, one oftwo (50%) tumors, and one (100%) congenital infection. Shunt malfunction was most common(n=15), and wasaccompanied by findings of enlarged ventricles, periventricular and peritubal edema, and abnormal location of theshunt tube. Symptoms and signs of increased intracranial pressure were also noted. Subdural hemorrhage andinfection were present infour cases each;findings of infection were enhancement of the ventricular wall, meninges,and parenchyma, as well as sonographically noted intraventricular septation and increased ventricular wall echo.Isolated lateral ventricle (n=4) or 4th ventricle (n=1) was persistently distended in spite of the presence of ashunt tube within the other ventricle. Collapsed ventricles, thick calvarium, and symptoms of increasedintracranial pressure were helpful in the diagnosis of slit ventricle syndrome(n=1). Immediate postoperativeintraventricular and parenchymal hemorrhage were noted in one case each. CONCLUSION: Shunt-related complicationswere found on postoperative images in 54% of pediatric patients with hydrocephalus; the frequency was highest incases of hydrocephalus caused by infection. Shunt malfunction occurred most frequently and each complication hadvarious imaging findings. For the diagnosis of post-operative shunt-related complication, continuous follow-upstudies are therefore necessary.

MR Imaging of Ischemic Parenchymal Lesions in Moyamoya Disease of Children

PURPOSE:To determine by means of MR imaging the ischemic status of parenchymal lesions in moyamoya disease. MATERIALS AND METHODS: Ninety-two MR images in 50 children with moyamoya disease were retrospectively reviewed. Ischemic parenchymal lesions were categorized according to the signal intensities of cortex and subcortical white matter. We also analyzed enhancement patterns, time sequential changes in the lesions, and the Prognosis for each patient, according to lesion type. RESULTS: Among one hundred and seventeen parenchymal abnormalities, 89 gyral lesions were seen in 43 children (86 %), predominantly in the frontal area (33.1%). Cortical parenchymal lesions were categorized as either type I - intermediate to high signal intensity (SI) on both T2 weighted (T2WI) and proton density images(PDI), and associated with low SI of the subcortical white matter; type II - high SI on T2WI and PDI, without low SI of the subcortical white matter; or type III - high SI on T2WI and iso SI on PDI. Thirty-three lesions were type I, ten were type II, and 43 were type III. Time sequential changes from type I to type II, and then to type III, were observed. The prognoses of patients with a type-I lesion were better than those of patients whose lesions were type II or III. CONCLUSION: Type I lesions presented with abnormal low signal intensity in the subcortical white matter, as seen on T2W1 images. This was the characteristic and earliest finding of ischemic parenchymal lesions in moyamoya disease; sequential MR images showed that type-I lesions progressed to type II or III.

MR Imaging of Tuberous Sclerosis: Emphasis on the Cortical and Subcortical Tubers

PURPOSE: To evaluate the frequency, location, and signal intensities of parenchymal (cortical andsubcortical) tubers and white matter lesion, as seen on MR images of patients with tuberous sclerosis. MATERIAL AND METHODS: Twenty patients diagnosed on the basis of clinical and MR findings as suffering from tuberoussclerosis, were retrospectively reviewed. Their ages ranged from 6 days to 21 years (mean, 5.2 years), and theywere divided into two groups according to age : under 18 months (n=9) and over 18 months(n=11). We analyzed thefrequency, location, and enhancement patterns of tubers and white matter lesions, and the difference of signalintensities between cortical and subcortical tubers according to age. RESULTS: Cortical tubers were detected in11 patients (55%), subcortical tubers in 18 (90%), and white matter lesions in 16 (80%). Subcortical tubers weremore frequently noted than cortical tubers and the two types did not always accompany each other. Cortical tuberswere most commonly located in the frontal lobe(10/11), followed by the parietal lobe(2/11), and temporallobe(2/11). Subcortical tubers were also most commonly located in the frontal lobe(17/18), followed by thetemporal lobe(10/18). White matter lesions were also frequently observed in the frontal lobe(13/16) and wererelated to the location of parenchymal tubers in 12 of 16 white-mater lesions. There were no lesions in thecerebellum. The signal intensities of cortical and subcortical tubers were different in all patients. Those ofsubcortical tubers showed no significant difference between the two age groups, but in patients under 18 months,signal intensity on T1WI tended to be high(5/6), and on T2WI, tended to be low(5/6). In 15 patients, Gd-DTPAenhanced MR images showed no demonstrable enhancement, except in one case involving white-matter lesion. CONCLUSION: Both cortical and subcortical tubers were commonly located in the frontal lobe, but the latter weremore frequently observed than the former. Subcortical tubers did not always accompany cortical tubers, and on MRimaging, the signal intensities of the two types were different in all cases. Differentiation of cortical andsubcortical tubers by MR imaging may therefore help analyze the parenchymal tubers seen in tuberous sclerosis.

MR Findings of Cerebral Palsy: Comparison Between Preterm Patients and Fullterm Patients

PURPOSE: To observe the MR findings of cerebral palsy by evaluating cerebral damage resulting from hypoxic ischemic injury and other variable causes and to compare the findings between preterm and full-term patients. MATERIALS AND METHODS: We reviewed the MR findings of 102 cerebral palsy patients (71 full-term and 31 preterm). These were analysed with regard to deep and peripheral white matter, gray matter, basal ganglia, the thalamus, brainstem, cerebellum, corpus callosum and ventricles, according to the pattern of injury such as hypoxic ischemic injury, migration anomaly and early intrauterine injury, the findings of full-term and preterm patients were then compared. RESULTS: MR findings of preterm patients (n=31) were as follows ; hypoxic ischemic injury (n=26), normal (n=2), and migration anomaly (n=3), while those of full-term patients (n=71) were hypoxic ischemic injury (n=41), normal (n=24), migration anomaly (n=4), early uterine injury (n=2), and perirolandic ischemic injury (n=6); in 5 patients, this latter condition was combined with status marmoratus. Periventricular leukomalacia was the most common finding in both preterm patients and full-term patients; selective neuronal necrosis, parasagittal injury and perirolandic injury were observed only in full-term patients. CONCLUSION: On MRI, variable findings of cerebral palsy were clearly observed; periventricular leukomalacia was the most common finding in both preterm and full-term patients.

Imaging Findings of Pediatric Oligodendroglioma

PURPOSE: The purpose of this study is to describe the imaging characteristics of oligodendroglioma in childhood. MATERIALS AND METHODS: Eight CT scans and 12 MR images were retrospectively reviewed in 12 children (mean age, 9.5 years) with pathologically-proven oligodendroglioma. The most frequent symptoms were seizure and headache, with a mean duration before diagnosis of 21 months. Location, MR signal intensity, calcification,intratumoral hemorrhage, cystic change, peritumoral edema and contrast enhancement were retrospectively analyzed. RESULTS: The supratentorial location was most frequent (9/12, 75%) and the majority of tumors were located peripherally or subcortically (7/9, 78%). On MR, most tumors demonstrated low signal intensity on T1WI and high signal intensity on T2WI ; cystic change was frequent (10/12, 83%). Tumor enhancement was seen in 60% of cases (6/10), with various enhancement patterns. Intratumoral hemorrhage was seen in two cases. On CT, the tumors were usually hypodense and calcification was noted in two cases (2/8, 25%). Peritumoral edema and mass effect of the tumor were seen in five (5/12,42%). Hydrocephalus was associated in two cases. CONCLUSION: In childhood, most oligodendrogliomas demonstrate a peripherally located supratentorial mass, with frequent cystic change. Calcification or intratumoral hemorrhage were less frequent than in previously reported adult series.

Hypoxic Ischemic Encephalopathy in Children: CT Findings Related to Prognosis

PURPOSE: To evaluate prognosis-related CT findings in hypoxic ischemic encephalopathy. MATERIALS AND METHODS: For the purpose of prognosis, 28 children with a clinical history and CT findings suggestive of hypoxic ischemic encephalopathy (HIE) were restrospectively reviewed. The diagnostic criteria for HIE, as seen on CT scanning, were as follows : 1, ventricular collapse ; 2, effacement of cortical sulci ; 3, prominent enhancement of cortical vessels ; 4, poor differentiation of gray and white matter ; 5, reversal sign ; 6, obliteration of perimesencephalic cistern ; 7, high density on tentorial edge, as seen on precontrast scans ; and 8, low density in thalamus, brain stem and basal ganglia. On the basis of clinical outcome, we divided the patients into three groups, as follows : group I(good prognosis) ; group II(neurologic sequelae), and group III(vegetative state or expire), and among these, compared CT findings. RESULTS: There were thirteen patients in group I, six in group II, and nine in group III. Ventricular collapse, effacement of cortical sulci, and prominent enhancement of cortical vessels were noted in all groups, whereas poor differentiation of gray and white matter, reversal sign, obliteration of perimesencephalic cistern, high density on tentorial edge, on precontrast scan, and low density in brain stem and basal ganglia were observed only in groups II and III. CONCLUSION: CT findings showed distinct differences between groups in whom prognosis was good, and in whom it was poor. An awareness of poor prognostic CT findings may be clinically helpful in the evaluation of patients with hypoxic ischemic encephalopathy.