Arastoo Vossough

Brain maturation is delayed in infants with complex congenital heart defects.

OBJECTIVE Small head circumferences and white matter injury in the form of periventricular leukomalacia have been observed in populations of infants with severe forms of congenital heart defects. This study tests the hypothesis that congenital heart defects delay in utero structural brain development. METHODS Full-term infants with hypoplastic left heart syndrome or transposition of the great arteries were prospectively evaluated with preoperative brain magnetic resonance imaging. Patients with independent risk factors for abnormal brain development (shock, end-organ injury, or intrauterine growth retardation) were excluded. Outcome measures included head circumferences and the total maturation score on magnetic resonance imaging. Total maturation score is a previously validated semiquantitative anatomic scoring system used to assess whole brain maturity. The total maturation score evaluates 4 parameters of maturity: (1) myelination, (2) cortical infolding, (3) involution of glial cell migration bands, and (4) presence of germinal matrix tissue. RESULTS The study cohort included 29 neonates with hypoplastic left heart syndrome and 13 neonates with transposition of the great arteries at a mean gestational age of 38.9 +/- 1.1 weeks. Mean head circumference was 1 standard deviation below normal. The mean total maturation score for the cohort was 10.15 +/- 0.94, significantly lower than reported normative data in infants without congenital heart defects, corresponding to a delay of 1 month in structural brain development. CONCLUSION Before surgery, term infants with hypoplastic left heart syndrome and transposition of the great arteries have brains that are smaller and structurally less mature than expected. This delay in brain development may foster susceptibility to periventricular leukomalacia in the preoperative, intraoperative, and postoperative periods.

Differentiation between Glioblastomas, Solitary Brain Metastases, and Primary Cerebral Lymphomas Using Diffusion Tensor and Dynamic Susceptibility Contrast-Enhanced MR Imaging

More on the eternal question: what can we use to differentiate preoperatively glioblastomas, metastases, and lymphomas? Here, the authors investigated whether diffusion tensor imaging and gadolinium perfusion studies could be used for this purpose. They evaluated 26 GBMs, 25 brain metastases, and 16 primary cerebral lymphomas with these techniques. Basically, GBMs showed lower fractional anisotropy and higher perfusion patterns. The best predictive data obtained were the apparent diffusion coefficients from enhancing tumor regions and the perfusion (cerebral blood volume) from the peritumoral regions. Although this is probably something that we all use on a daily basis, it is nice to see it reported in such an organized and careful fashion. BACKGROUND AND PURPOSE: Glioblastomas, brain metastases, and PCLs may have similar enhancement patterns on MR imaging, making the differential diagnosis difficult or even impossible. The purpose of this study was to determine whether a combination of DTI and DSC can assist in the differentiation of glioblastomas, solitary brain metastases, and PCLs. MATERIALS AND METHODS: Twenty-six glioblastomas, 25 brain metastases, and 16 PCLs were retrospectively identified. DTI metrics, including FA, ADC, CL, CP, CS, and rCBV were measured from the enhancing, immediate peritumoral and distant peritumoral regions. A 2-level decision tree was designed, and a multivariate logistic regression analysis was used at each level to determine the best model for classification. RESULTS: From the enhancing region, significantly elevated FA, CL, and CP and decreased CS values were observed in glioblastomas compared with brain metastases and PCLs (P < .001), whereas ADC, rCBV, and rCBVmax values of glioblastomas were significantly higher than those of PCLs (P < .01). The best model to distinguish glioblastomas from nonglioblastomas consisted of ADC, CS (or FA) from the enhancing region, and rCBV from the immediate peritumoral region, resulting in AUC = 0.938. The best predictor to differentiate PCLs from brain metastases comprised ADC from the enhancing region and CP from the immediate peritumoral region with AUC = 0.909. CONCLUSIONS: The combination of DTI metrics and rCBV measurement can help in the differentiation of glioblastomas from brain metastases and PCLs.

Efficacy of Texture, Shape, and Intensity Feature Fusion for Posterior-Fossa Tumor Segmentation in MRI

Our previous works suggest that fractal texture feature is useful to detect pediatric brain tumor in multimodal MRI. In this study, we systematically investigate efficacy of using several different image features such as intensity, fractal texture, and level-set shape in segmentation of posterior-fossa (PF) tumor for pediatric patients. We explore effectiveness of using four different feature selection and three different segmentation techniques, respectively, to discriminate tumor regions from normal tissue in multimodal brain MRI. We further study the selective fusion of these features for improved PF tumor segmentation. Our result suggests that Kullback-Leibler divergence measure for feature ranking and selection and the expectation maximization algorithm for feature fusion and tumor segmentation offer the best results for the patient data in this study. We show that for T1 and fluid attenuation inversion recovery (FLAIR) MRI modalities, the best PF tumor segmentation is obtained using the texture feature such as multifractional Brownian motion (mBm) while that for T2 MRI is obtained by fusing level-set shape with intensity features. In multimodality fused MRI (T1, T2, and FLAIR), mBm feature offers the best PF tumor segmentation performance. We use different similarity metrics to evaluate quality and robustness of these selected features for PF tumor segmentation in MRI for ten pediatric patients.

Seizures as a presenting symptom of acute arterial ischemic stroke in childhood

OBJECTIVES To define the incidence of seizures as a presenting symptom of acute arterial ischemic stroke (AIS) in children and to determine whether younger age, infarct location, or AIS etiology were risk factors for seizure at AIS presentation. STUDY DESIGN Children aged 2 months to 18 years presenting with AIS between January 2005 and December 2008 were identified from a single center prospective pediatric stroke registry. Clinical data were abstracted, and a neuroradiologist reviewed imaging studies. RESULTS Among the 60 children who met our inclusion criteria, 13 experienced seizure at stroke presentation (22%). Median age was significantly younger in children who presented with seizures than in those who did not (1.1 years vs 10 years; P = .0009). Seizures were accompanied by hemiparesis in all patients. Three of 4 children with clinically overt seizures at presentation also had nonconvulsive seizures on continuous electroencephalography monitoring. CONCLUSIONS Twenty-two percent of children with acute AIS present with seizures. Seizures were always accompanied by focal neurologic deficits. Younger age was a risk factor for seizures at presentation. Seizure at presentation was not associated with infarct location or etiology. Nonconvulsive seizures may occur during the acute period.

Risk of Later Seizure After Perinatal Arterial Ischemic Stroke: A Prospective Cohort Study

OBJECTIVE: Although acute seizures are common among neonates with arterial ischemic stroke (AIS), the incidence of subsequent seizures is unknown. The goals of this study were to determine the incidence of seizures following hospital discharge after perinatal acute AIS, and to assess lesion characteristics associated with later seizure occurrence. METHODS: Neonates with confirmed acute AIS on MRI were identified through a prospective stroke registry. Clinic visits and telephone follow-up identified occurrence of seizures after hospital discharge. MRI scans were graded for size and characteristics of infarct, and associations with seizures after stroke were analyzed. RESULTS: At a mean (SD) follow-up of 31.3 (16.1) months, 11 of 46 (23.9%) patients with perinatal AIS had at least 1 seizure. Five patients had a single episode of seizure, and 6 developed epilepsy. The Kaplan-Meier probability of remaining seizure-free at 3 years was 73%. Stroke size on MRI was significantly associated with development of later seizures, with an incidence rate of later seizures 6.2 times higher among those with larger stroke size. CONCLUSIONS: Seizures occurred in <25% of patients during initial follow-up after perinatal AIS. Of those with seizures, nearly half had a single episode of seizure and not early epilepsy. Larger stroke size was associated with higher risk of seizure. These data suggest that prolonged treatment with anticonvulsant agents may not be indicated for seizure prophylaxis after perinatal AIS. These findings may help guide clinicians in counseling families and could form the basis for much-needed future research in this area.

Magnetic resonance imaging of the penis

Although magnetic resonance imaging (MRI) of the penis is an uncommonly performed examination, MRI can provide valuable information in a wide variety of penile disorders. We describe the techniques and safety issues pertinent to MRI of the penis and then discuss the role and limitations of MRI in the investigation of penile trauma, selected benign diseases, neoplasms, vascular lesions, and penile prostheses.

Proton magnetic resonance spectroscopy in differentiating glioblastomas from primary cerebral lymphomas and brain metastases.

Objective: To differentiate glioblastomas, primary cerebral lymphomas (PCLs), and brain metastases using multivoxel proton magnetic resonance (MR) spectroscopic imaging. Methods: A total of 56 patients with brain neoplasms underwent MR imaging and proton MR spectroscopic imaging. The data were analyzed from contrast-enhancing and peritumoral regions (PTR). N-acetylaspartate/creatine (Cr), choline (Cho)/Cr, glutamate+glutamine/Cr, myo-inositol/Cr, and lipids+lactate/Cr ratios were computed, and pairwise comparisons between neoplasms were made using Mann-Whitney U tests. Results: The PTR demonstrated most significant differences in metabolite ratios. The Cho/Cr ratio in glioblastomas (0.46 [0.01]) was significantly higher than that in metastases (0.38 [0.02], P = 0.01). Significantly elevated Cho/Cr levels were also noted in PCLs (0.48 [0.03]) compared with those in metastases (P = 0.04). In addition, PCLs also demonstrated significantly higher lipids+lactate/Cr levels (11.83 [2.59]) compared with glioblastomas (4.50 [0.59], P = 0.003) and metastases (2.79 [0.33], P = 0.001). Conclusions: Proton MR spectroscopic imaging from PTR may assist in the differentiation of glioblastomas, metastases, and PCLs.

Intracranial Vessel Wall MRI: Principles and Expert Consensus Recommendations of the American Society of Neuroradiology

SUMMARY: Intracranial vessel wall MR imaging is an adjunct to conventional angiographic imaging with CTA, MRA, or DSA. The technique has multiple potential uses in the context of ischemic stroke and intracranial hemorrhage. There remain gaps in our understanding of intracranial vessel wall MR imaging findings and research is ongoing, but the technique is already used on a clinical basis at many centers. This article, on behalf of the Vessel Wall Imaging Study Group of the American Society of Neuroradiology, provides expert consensus recommendations for current clinical practice.

Differentiation between oligodendroglioma genotypes using dynamic susceptibility contrast perfusion-weighted imaging and proton MR spectroscopy.

These authors used perfusion imaging and MR spectroscopy to differentiate oligodendrogliomas with 1p/19q deletions from those with intact alleles. NAA/Cr, Cho/Cr, Glx/Cr, myo-inositol/Cr and the presence of lipids and lactate were assessed in areas of maximum perfusion in 40 patients. This study showed that as groups, integration of the MRS indices from the region containing the highest cerebral blood volume was useful in distinguishing tumors with 1p/19q abnormalities from those that did not have them. BACKGROUND AND PURPOSE: Oligodendrogliomas with 1p/19q chromosome LOH are more sensitive to chemoradiation therapy than those with intact alleles. The usefulness of dynamic susceptibility contrast–PWI-guided 1H-MRS in differentiating these 2 genotypes was tested in this study. MATERIALS AND METHODS: Forty patients with oligodendrogliomas, 1p/19q LOH (n = 23) and intact alleles (n = 17), underwent MR imaging and 2D-1H-MRS. 1H-MRS VOI was overlaid on FLAIR images to encompass the hyperintense abnormality on the largest cross-section of the neoplasm and then overlaid on CBV maps to coregister CBV maps with 1H-MRS VOI. rCBVmax values were obtained by measuring the CBV from each of the selected 1H-MRS voxels in the neoplasm and were normalized with respect to contralateral white matter. Metabolite ratios with respect to ipsilateral Cr were computed from the voxel corresponding to the rCBVmax value. Logistic regression and receiver operating characteristic analyses were performed to ascertain the best model to discriminate the 2 genotypes of oligodendrogliomas. Qualitative evaluation of conventional MR imaging characteristics (patterns of tumor border, signal intensity, contrast enhancement, and paramagnetic susceptibility effect) was also performed to distinguish the 2 groups of oligodendrogliomas. RESULTS: The incorporation of rCBVmax value and metabolite ratios (NAA/Cr, Cho/Cr, Glx/Cr, myo-inositol/Cr, and lipid + lactate/Cr) into the multivariate logistic regression model provided the best discriminatory classification with sensitivity (82.6%), specificity (64.7%), and accuracy (72%) in distinguishing 2 oligodendroglioma genotypes. Oligodendrogliomas with 1p/19q LOH were also more associated with paramagnetic susceptibility effect (P < .05). CONCLUSIONS: Our preliminary results indicate the potential of combing PWI and 1H-MRS to distinguish oligodendroglial genotypes.

Hemorrhagic Transformation of Childhood Arterial Ischemic Stroke

Background and Purpose— The objective of this study was to describe the occurrence of hemorrhagic transformation (HT) among children with arterial ischemic stroke within 30 days after symptom onset and to describe clinical factors associated with HT. Methods— Sixty-three children aged 1 month to 18 years with arterial ischemic stroke between January 2005 and November 2008 were identified from a single-center prospective pediatric stroke registry. All neuroimaging studies within 30 days of stroke were reviewed by a study neuroradiologist. Hemorrhage was classified according to the European Cooperative Acute Stroke Study-1 definitions. Association of HT with clinical factors, systemic anticoagulation, stroke volume, and outcome was analyzed. Results— HT occurred in 19 of 63 children (30%; 95% CI, 19% to 43%), only 2 (3%) of whom were symptomatic. Hemorrhage classification was hemorrhagic infarction (HI)1 in 14, HI2 in 2, parenchymal hematoma (PH)1 in 2, and PH2 in 1. HT was less common in children with vasculopathy (relative risk, 0.27; 95% CI, 0.07 to 1.06; P=0.04) than in those with other stroke mechanisms. HT was not significantly associated with anticoagulation versus antiplatelet therapy (relative risk, 0.6; 95% CI, 0.2 to 1.5; P=0.26) but was associated with larger infarct volumes (P=0.0084). In multivariable analysis, worse Pediatric Stroke Outcome Measure scores were associated with infarct volume ≥5% of total supratentorial brain volume (OR, 4.0; 95% CI, 1.1 to 15; P=0.04), and a trend existed toward association of worse Pediatric Stroke Outcome Measure scores with HT (OR, 4.0; 95% CI, 0.9 to 18; P=0.07). Conclusions— HT occurred in 30% of children with arterial ischemic stroke within 30 days. Most hemorrhages were petechial and asymptomatic. Infarct volume was associated with HT and worse outcome.