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E R Melhem

Publications and source records attributed to E R Melhem.

At least 19 recordsLinked to original sources
PubMed2001

Diffusion tensor brain MR imaging in X-linked cerebral adrenoleukodystrophy.

Brain diffusion tensor MRI of 11 boys with X-linked adrenoleukodystrophy was performed. The authors determined quantitative isotropic apparent diffusion coefficient (ADC(i)) and fractional anisotropy (FA) values in the white matter. ADC(i) and FA values in the affected white matter were significantly different from those in normal-appearing white matter. Zonal ADC(i) and FA gradations, which might originate from well-established histopathologic zonal changes, existed within affected white matter.

Adolescent↗
PubMed2001

Proton magnetic resonance spectroscopy of choroid plexus tumors in children.

A variety of lesions may present as intraventricular masses in children. We report quantitative proton magnetic resonance spectroscopy (MRS) of two intraventricular tumors of the choroid plexus: choroid plexus carcinoma (CPC) and choroid plexus papilloma (CPP). Both lesions were characterized by high levels of choline-containing compounds and a complete absence of creatine and the neuronal/axonal marker N-acetyl aspartate. The CPC showed higher levels of choline compared to the CPP, and it also had elevated lactate. These preliminary results, if confirmed in a larger cohort of patients, indicate that proton MRS may have a role in the presurgical diagnosis of choroid plexus tumors in children, which may also have important implications for therapy and prognosis.

Aspartic Acid↗
PubMed2001

Dysembryoplastic neuroepithelial tumor-like neoplasm of the septum pellucidum: a lesion often misdiagnosed as glioma: report of 10 cases.

The authors report a series of 10 low-grade neoplasms arising in the midline anteriorly in the region of the septum pellucidum with many of the histologic features of dysembryoplastic neuroepithelial tumor (DNT). The patients (five female, five male) ranged in age from 6 to 35 years (mean age, 21.5 years). The most common presenting symptoms were headache, nausea and vomiting, and visual disturbances. Radiographically, the tumors extended into the lateral ventricles from the septal region and obstructed the foramen of Monro. Varying degrees of hydrocephalus were present. The lesions were lobular, well-delineated, hypointense to brain on T1-weighted magnetic resonance imaging, and hyperintense on T2-weighted images. They were uniformly nonenhancing or showed only minimal peripheral enhancement. The tumors, in aggregate, had the histologic features of DNT. These included a mucin-rich background, oligodendrocyte-like cells, "floating neurons," and a "specific glioneuronal element." Seven patients underwent gross total resection and two underwent subtotal resection. No patients received adjuvant chemotherapy or radiotherapy. On follow-up (n = 6; median, 14 months), all tumors had either not recurred or were radiologically stable. On the basis of both neuroimaging and histopathology, DNT-like lesions should be considered in the differential diagnosis of midline intraventricular tumors in children and young adults. Distinction from more aggressive neoplasms is essential because these tumors appear to behave in a benign fashion.

Adolescent↗
PubMed2001

Second surgery for recurrent pilocytic astrocytoma in children.

Pilocytic astrocytoma (PA) is the most common childhood brain tumor. In cases where the tumor progresses or recurs following primary surgical resection, the appropriate treatment is unclear. Options include chemotherapy, radiation therapy, surgical resection or a combination thereof. To analyze the utility of further surgery, we performed a retrospective, single-institution review of pediatric patients with recurrent PAs from 1990 to 1999 who were treated with a second surgical resection. Patients were excluded if they received adjuvant chemotherapy or radiation therapy. Twenty cases were identified. Tumor locations included: cerebral hemisphere (3), cerebellum (7), optic pathway/hypothalamus (5), thalamus (1) and brainstem (4). The indication for 4 surgeries included an enlarging tumor-associated cyst. At second surgery, 10 of 20 patients had a gross total resection (GTR), 2 a near total resection (NTR), and the remaining 8 patients had a subtotal resection (STR). No patients have died. Two of 10 tumors after GTR, 0 of 2 tumors after NTR, and 7 of 8 tumors after STR had second recurrence/progression at a mean of 15 months (range 4-33 months) following second surgery. The remaining 11 patients are recurrence/progression-free at a mean of 40.7 months (range 19-119 months). Surgery for tumors or midline structures rarely resulted in a GTR (1 of 10 cases). Surgery for tumors located in the cerebral hemispheres or cerebellum resulted in GTR or NTR in all cases and can result in long periods of progression-free survival without further adjuvant treatment.

Adolescent↗
PubMed2001

Effect of T1 relaxation time on lesion contrast enhancement in flair MR imaging: a study using computer-generated brain maps.

OBJECTIVE: Using computer-generated brain maps, we aimed to define T1 relaxation time thresholds above which a T2 hyperintense (compared with surrounding white matter) lesion became hypointense on fluid-attenuated inversion recovery (FLAIR) MR imaging. Thresholds were identified for FLAIR MR imaging sequences with different echo times (TEs). CONCLUSION: Thresholds for T1 relaxation times increased as TE increased during FLAIR MR imaging sequences. Such thresholds defined the transition from hyperintense to hypointense lesions.

Adult↗
PubMed2001

Accuracy for detection of simulated lesions: comparison of fluid-attenuated inversion-recovery, proton density--weighted, and T2-weighted synthetic brain MR imaging.

OBJECTIVE: The objective of our study was to determine the effects of MR sequence (fluid-attenuated inversion-recovery [FLAIR], proton density--weighted, and T2-weighted) and of lesion location on sensitivity and specificity of lesion detection. MATERIALS AND METHODS: We generated FLAIR, proton density-weighted, and T2-weighted brain images with 3-mm lesions using published parameters for acute multiple sclerosis plaques. Each image contained from zero to five lesions that were distributed among cortical-subcortical, periventricular, and deep white matter regions; on either side; and anterior or posterior in position. We presented images of 540 lesions, distributed among 2592 image regions, to six neuroradiologists. We constructed a contingency table for image regions with lesions and another for image regions without lesions (normal). Each table included the following: the reviewer's number (1--6); the MR sequence; the side, position, and region of the lesion; and the reviewer's response (lesion present or absent [normal]). We performed chi-square and log-linear analyses. RESULTS: The FLAIR sequence yielded the highest true-positive rates (p < 0.001) and the highest true-negative rates (p < 0.001). Regions also differed in reviewers' true-positive rates (p < 0.001) and true-negative rates (p = 0.002). The true-positive rate model generated by log-linear analysis contained an additional sequence-location interaction. The true-negative rate model generated by log-linear analysis confirmed these associations, but no higher order interactions were added. CONCLUSION: We developed software with which we can generate brain images of a wide range of pulse sequences and that allows us to specify the location, size, shape, and intrinsic characteristics of simulated lesions. We found that the use of FLAIR sequences increases detection accuracy for cortical-subcortical and periventricular lesions over that associated with proton density- and T2-weighted sequences.

Adult↗
PubMed2001

T2 relaxation measurements in X-linked adrenoleukodystrophy performed using dual-echo fast fluid-attenuated inversion recovery MR imaging.

SUMMARY: The purpose of this study was to determine whether dual-echo fast fluid-attenuated inversion recovery MR imaging and corresponding T2 brain maps can show different zones in the affected white matter of patients with cerebral X-linked adrenoleukodystrophy. Ten male patients with cerebral X-linked adrenoleukodystrophy underwent imaging performed using dual-echo fast fluid-attenuated inversion recovery and dual-echo conventional spin-echo MR sequences. Corresponding T2 relaxation maps of the brain were generated. On the basis of dual-echo fast fluid-attenuated inversion recovery images and T2 maps, the affected white matter could be divided into two distinct zones in four patients with cerebral X-linked adrenoleukodystrophy.

Adolescent↗
PubMed2001

Multi-slice proton MR spectroscopy and diffusion-weighted imaging in methylmalonic acidemia: report of two cases and review of the literature.

SUMMARY: Methylmalonic acidemia is an inborn disorder of amino acid metabolism that commonly presents with neurologic deficits. We present the results of multi-slice proton MR spectroscopy and diffusion-weighted imaging of the brain in two patients with methylmalonic acidemia. The findings consisted of restricted diffusion and elevated lactate in the globi pallidi, compatible with acute infarction (patient 1) and elevated lactate in CSF (patient 2).

Adolescent↗
PubMed2001

Time-resolved contrast-enhanced carotid MR angiography using sensitivity encoding (SENSE).

We describe a time-resolved, contrast-enhanced carotid MR angiographic technique using a 3D gradient-echo sequence in combination with a sensitivity-encoding scheme. We delineate the steps involved in generating the dynamic MR angiographic images, discuss issues related to image quality, and outline differences between this technique and recently reported similar methods that implement multiple parallel receivers to reduce imaging time.

Adult↗
PubMed2000

Cervical spondylosis: contrast-enhanced magnetization transfer prepulsed 3D turbo field echo MR imaging.

Magnetic resonance (MR) imaging of the cervical spine with axial, low flip angle three-dimensional (3D) gradient-echo sequences is limited by long acquisition times and also by increased sensitivity to extrinsic and intrinsic magnetic field inhomogeneity, magnetic susceptibility differences, chemical shifts, and cerebrospinal fluid pulsatility. We attempted to assess the performance of gadolinium-enhanced, magnetization transfer (MT) prepulsed 3D fast gradient-echo sequences in demonstrating spondylotic changes of the cervical spine. Twenty patients with known cervical spine spondylosis were prospectively imaged in the axial plane using two gradient-echo-based MR techniques: 3D fast field echo (FFE) and gadolinium-enhanced, MT prepulsed, segmented turbo field echo (TFE). An average of 58 neural foramina on the 3D FFE images and 47 neural foramina on the contrast-enhanced TFE images were judged to be narrowed. The degree of neural foraminal narrowing was significantly less on the contrast-enhanced TFE images compared with the FFE images (P <0.001). Contrast-enhanced, MT prepulsed, segmented 3D TFE MR imaging has potential for ameliorating some of the limitations encountered in the more widely used gradient-echo techniques.

Cervical Vertebrae↗
PubMed2000

X-Linked adrenoleukodystrophy: overview and prognosis as a function of age and brain magnetic resonance imaging abnormality. A study involving 372 patients.

The phenotypic expression of X-linked adrenoleukodystrophy (X-ALD) ranges from the rapidly progressive childhood cerebral form to the milder adrenomyeloneuropathy (AMN) in adults. It is not possible to predict phenotype by mutation analysis or biochemical assays. This study reports on 372 patients ranging in age from less than 3 years to adulthood, who have been followed at the Kennedy Krieger Institute. With the aim of determining whether a method could be developed to predict clinical course by analysis of data available at time of first contact, the patients were subdivided into 18 subgroups on the basis of age and the extent of brain magnetic resonance (MRI) abnormality utilizing the MRI scoring system devised by Loes et al. Scores to grade degree of neurologic and neuropsychologic impairment were also developed. There was strong correlation between MRI and the neurology and neuropsychology scores at baseline. Information based exclusively on age and MRI score at time of first contact was highly predictive of future clinical course and should aid the evaluation of the effects of bone marrow transplantation and the selection of patients for this procedure, as well as the evaluation of other therapies that may be developed in the future.

Adrenoleukodystrophy↗
PubMed2000

Neuroimaging: applications in disorders of early brain development.

Neuroimaging techniques have established new connections between etiological factors and disorders of early brain development. Neuroimaging has also strengthened the link between patterns of selective vulnerability in the developing brain and clinical syndromes, especially cerebral palsy. Both computed tomography (CT) and magnetic resonance imaging (MRI) identify early developmental malformations, including neural tube defects, callosal dysgenesis, neuronal migration disorders, posterior fossa malformations, and hydrocephalus. Periventricular white matter damage, most commonly seen in premature infants, is best visualized by cranial ultrasonography in the neonatal period and on MRI later in childhood. In term infants and children with genetic metabolic diseases, various applications of nuclear magnetic resonance, including MRI, have important diagnostic roles. The utility of diffusion-weighted imaging, MR spectroscopy, and functional MRI to further understanding of brain injury, biochemistry, and function is under active investigation. In summary, selecting the appropriate neuroimaging technique can improve diagnosis and management of childhood neurodevelopmental disorders.

Brain↗
PubMed2000

Periventricular leukomalacia: relationship between lateral ventricular volume on brain MR images and severity of cognitive and motor impairment.

PURPOSE: To evaluate the utility of lateral ventricular volume measurements in predicting motor and cognitive impairment severity in children with periventricular leukomalacia (PVL), with or without seizures. MATERIALS AND METHODS: The charts of children with spastic cerebral palsy and PVL documented on brain magnetic resonance (MR) images were reviewed. Affected children were grouped by motor and cognitive impairment severity and seizure disorder. An age-matched control group was established. Lateral ventricular volumes were measured on two-dimensional T2-weighted spin-echo MR images. Analysis of variance was used to identify significant differences in mean lateral ventricular volume between groups. Paired analyses of differences were performed with the Bonferroni t method. RESULTS: Thirty-six children (24 boys, 12 girls) with spastic cerebral palsy and PVL and 21 age-matched control subjects (14 boys, seven girls) were identified. Mean lateral ventricular volumes of the moderate and marked motor deficit groups were significantly larger than those of the control and mild motor deficit groups (F = 29.24; alpha = .01). Mean lateral ventricular volumes of all cognitive impairment groups were significantly larger than those of the control and no-cognitive-impairment groups (F = 21.101 alpha = .01). There was no difference in mean lateral ventricular volume between children with PVL with or without seizures. CONCLUSION: Lateral ventricular volume measurements can be used as quantitative markers of clinical impairment severity and as clinical outcome predictors before formal testing is possible.

Brain Damage, Chronic↗
PubMed2000

Tectal gliomas: natural history of an indolent lesion in pediatric patients.

The mesencephalic tectal glioma is a distinctive form of brain stem glioma with an unusually benign clinical course. Periaqueductal location, lack of contrast enhancement, and long periods of stability are classic features. The clinical management of these lesions, especially at the time of radiographic enlargement varies widely in the published literature. It is unclear whether these progressive lesions need to be treated. Accordingly, clinical and radiologic features of 7 patients were reviewed, with attention to the clinical course of the disease after radiologic enlargement. The age at diagnosis ranged from 3.3 to 16.6 years. Six of 7 had MRI tumor enlargement beginning 0.3-5.7 years after initial diagnosis. One of these 6 patients had radiographic progression coupled with a new clinical symptom which was treated with stereotactic radiation therapy. The remaining 5 patients with MRI progression and normal neurological exams were not treated and remain free of new neurologic deficits 1.8-6.9 years after the first radiographic tumor enlargement. The results suggest that pediatric tectal gliomas are a very low-grade lesion. Conservative management in the absence of new clinical symptoms could be argued, reserving radiotherapy or chemotherapy for clinical progression.

Adolescent↗
PubMed2000

Physiologic variations in dural venous sinus flow on phase-contrast MR imaging.

OBJECTIVE: Our study quantifies normal physiologic variations of dural sinus flow using phase-contrast MR imaging. SUBJECTS AND METHODS: Fifteen volunteers were imaged using nontriggered and triggered phase-contrast MR venography of the superior sagittal and transverse sinuses. Triggered scans were obtained during regular breathing; nontriggered scans were obtained during regular breathing, breath-holding, deep inspiratory breath-holding, and deep expiratory breath-holding. Analysis of variance, Bonferroni method, and Dunn post hoc analysis were used to determine any significant differences in the mean flow and velocity between the different breathing maneuvers. A paired t test was used to compare flow between sinuses during regular breathing. RESULTS: Deep inspiratory breath-holding and deep expiratory breath-holding resulted in a significant decrease in blood flow and velocity in all dural sinuses compared with regular breathing. During deep inspiratory breath-holding, blood flow decreased 30.8% in the superior sagittal sinus, 19.7% in the left transverse sinus, and 19.1% in the right transverse sinus. Similarly, during deep expiratory breath-holding, blood flow decreased 30.2% in the superior sagittal sinus, 20.8% in the left transverse sinus, and 20.3% in the right transverse sinus. The sum of the flow in the transverse sinuses was significantly greater than in the sagittal sinus. Normal pulsatility of dural sinus blood velocity was also characterized for all measured sinuses. CONCLUSION: Characterization of variations in dural sinus velocity and flow as a function of the cardiac cycle and breathing maneuvers, using phase-contrast MR imaging, may help separate physiologic from pathologic changes of flow resulting from conditions that influence the cerebrovascular circulation.

Adult↗
PubMed2000

Registration of three-dimensional MR and CT studies of the cervical spine.

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.

Adult↗