Noriko Salamon | University of California, Los Angeles (original) (raw)

Papers by Noriko Salamon

Radiographics a Review Publication of the Radiological Society of North America Inc, Jul 1, 2008

Pediatric patients with intractable epilepsy represent a challenging clinical population. However... more Pediatric patients with intractable epilepsy represent a challenging clinical population. However, recent advances in neuroimaging with a multimodality imaging approach that combines fluorine 18 fluorodeoxyglucose positron emission tomography, magnetoencephalography, diffusion tensor imaging, and magnetic source imaging with conventional magnetic resonance imaging continue to improve diagnosis and treatment in affected patients. These advances are increasing the understanding of the underlying disease process and improving the ability to noninvasively detect epileptogenic foci that in the past went undetected and whose accurate localization is crucial for a good outcome following surgical resection.

American Journal of Neuroradiology, Oct 1, 2008

The effect of various contrast-dose regimens for cerebral MR venography (MRV) has not been previo... more The effect of various contrast-dose regimens for cerebral MR venography (MRV) has not been previously evaluated at 3T, to our knowledge. Our purpose was to evaluate and compare the diagnostic image quality resulting from half-versus-full-dose contrast regimens for high-spatial-resolution 3D cerebral MRV at 3T. Forty consecutive patients with known or suggested cerebrovascular disease underwent 3D high-spatial-resolution (0.7 x 0.6 x 0.9 mm(3)) cerebral contrast-enhanced MRV (CE-MRV) at 3T, by using an identical acquisition protocol. Patients were assigned to 1 of 2 groups: 1) full-dose (approximately 0.1 mmol/kg), and 2) half-dose (approximately 0.05 mmol/kg). Two readers evaluated the resulting images for overall image quality, venous structure definition, and arterial contamination. Signal intensity-to-noise-ratio (SNR) and contrast-to-noise-ratio (CNR) were evaluated in 8 consistent sites. Statistical analysis was performed by using Mann-Whitney U, Wilcoxon signed rank, and t tests and a kappa coefficient. Both readers scored venous-structure definition as excellent or sufficient for diagnosis in approximately 90% of segments for the full-dose group (kappa = 0.87) and in approximately 80% of segments for the half-dose group (kappa = 0.85). Delineation grades were significantly lower for small venous segments, including the middle cerebral, septal, superior cerebellar, inferior vermian, posterior tonsillar, and thalamostriate veins in the half-dose group (P &amp;lt; .01). No significant difference existed for arterial contamination grades between the 2 groups (P &amp;gt; .05). SNR and CNR values were lower in the half-dose group (P &amp;lt; .01). At 3T, high-spatial-resolution cerebral MRV can be performed with contrast doses as low as 7.5 mL, without compromising image quality as compared with full-dose protocols, except in the smallest veins, and without compromise of acquisition speed or spatial resolution.

Human pathology, Jan 19, 2016

Surgical Neurology, Jul 1, 2009

Background: Characterization of WM alteration using MR imaging is important in the pre-and intrao... more Background: Characterization of WM alteration using MR imaging is important in the pre-and intraoperative assessment of brain tumors. This study characterizes the extent and severity of WM tract alterations near brain tumors using DTI in an effort to determine preoperative viability or resectability of the adjacent WM tracts. Fractional anisotropy is an important DTI-derived metric of MR imaging. Methods: Twenty-one patients underwent MR DTI. Eighty-six WM tracts composed of 43 WM lesions paired with 43 contralateral WM hemispheric controls were categorized using FA.

Neuroimaging clinics of North America, 2015

Retrochiasmal visual pathways include optic tracts, lateral geniculate nuclei, optic radiations, ... more Retrochiasmal visual pathways include optic tracts, lateral geniculate nuclei, optic radiations, and striate cortex (V1). Homonymous hemianopsia and field defect variants with relatively normal visual acuity suggest that the lesions involve retrochiasmal pathways. From V1, visual input is projected to higher visual association areas that are responsible for perception of objects, faces, colors, and orientation. Visual association areas are classified into ventral and dorsal pathways. Damage to the ventral stream results in visual object agnosia, prosopagnosia, and achromatopsia. Balint syndrome, visual inattention, and pure alexia are examples of dorsal stream disorders. Posterior cortical atrophy can involve ventral and dorsal streams, often preceding dementia.

$Research paper thumbnail of (18F) Fluorodeoxyglucose-Positron-Emission Tomography and MR Imaging Coregistration for Presurgical Evaluation of Medically Refractory Epilepsy$

American Journal of Neuroradiology, Nov 1, 2009

ABSTRACT Purpose: Arterial spin labeling (ASL) has gained attention in evaluation of acute stroke... more ABSTRACT Purpose: Arterial spin labeling (ASL) has gained attention in evaluation of acute stroke as an alternative perfusion method that does not require contrast. We evaluate the agreement of ASL and dynamic susceptibility contrast (DSC) mismatch classification using a quantitative method in successfully recanalized patients. Methods: This retrospective study was performed using MR examinations acquired between 2010-2012. Inclusion criteria were: patients with acute stroke who underwent successful recanalization and acquisition of both ASL and DSC before and after revascularization. The volumes of DWI and hypoperfused (Tmax > 6 seconds) lesions were calculated on DSC using an automated software. The hypoperfusion volumes on ASL were calculated using a region of interest-based analysis. The ratios of volume of the hypoperfusion region to DWI lesion were calculated and used to classify the patients into 3 categories: 1) mismatch: ratio >2; 2) matched: 0.7 < ratio < 2; and 3) reperfused: ratio < 0.7. Intermodality agreement for mismatch categories was evaluated with Kappa test. Results: Seventeen patients met the inclusion criteria, resulting in 34 pair of ASL-DSC for comparison. The mean ± SD of the volumes of the DWI lesions was 14.2± 8 ml and 18.2 ± 13 ml before and after revascularization respectively. ASL overestimated the hypoperfusion volume in both pre and post-treatment groups (p<0.01) in comparison to DSC-Tmax lesion volume. In pre-treatment group, ASL-DWI and DSC-DWI mismatch categories agreed in 15 of 17 cases (88%) with high agreement (k=0.82; 95% CI, 0.3 –0.87). In post-treatment group, ASL-DWI and DSC-DWI mismatch categories agreed in 11 of 17 cases (64%) with moderate agreement (k=0.46; 95% CI,0.25-0.82). Out of 6 discrepant cases, three reperfused patients on DSC were categorized matched on ASL and 3 matched cases on DSC were classified as mismatch on ASL. Conclusion: ASL overestimates the DSC time to maximum lesion volume. There is only moderate agreement between ASL and DSC in mismatch classification of revascularized patients, suggestive of less sensitivity of ASL in detection of reperfusion. Improvement in ASL methods with varying degree post-labeling delay may be needed for evaluation of revascularized patients.

Neurology, Jan 6, 2015

To evaluate whether diffusion tensor imaging (DTI) can predict epileptogenic tubers by measuring ... more To evaluate whether diffusion tensor imaging (DTI) can predict epileptogenic tubers by measuring apparent diffusion coefficient (ADC), fractional anisotropy, axial diffusivity, and radial diffusivity in both tubers and perituberal tissue in pediatric patients with tuberous sclerosis complex (TSC) undergoing epilepsy surgery. We retrospectively selected 23 consecutive patients (aged 0.4-19.6 years, mean age of 5.2; 13 female, 10 male) who underwent presurgical DTI and subsequent surgical resection between 2004 and 2013 from the University of California-Los Angeles TSC Clinic. We evaluated presurgical examinations including video-EEG, brain MRI, (18)F-fluorodeoxyglucose-PET, magnetic source imaging, and intraoperative electrocorticography for determining epileptogenic tubers. A total of 545 tubers, 33 epileptogenic and 512 nonepileptogenic, were identified. Two observers generated the regions of interest (ROIs) of tubers (ROI(tuber)), the 4-mm-thick ring-shaped ROIs surrounding the tu...

PloS one, 2015

In the present study we investigated a combination of diffusion tensor imaging (DTI) and magnetic... more In the present study we investigated a combination of diffusion tensor imaging (DTI) and magnetic resonance spectroscopic (MRS) biomarkers in order to predict neurological impairment in patients with cervical spondylosis. Twenty-seven patients with cervical spondylosis were evaluated. DTI and single voxel MRS were performed in the cervical cord. N-acetylaspartate (NAA) and choline (Cho) metabolite concentration ratios with respect to creatine were quantified, as well as the ratio of choline to NAA. The modified mJOA scale was used as a measure of neurologic deficit. Linear regression was performed between DTI and MRS parameters and mJOA scores. Significant predictors from linear regression were used in a multiple linear regression model in order to improve prediction of mJOA. Parameters that did not add value to model performance were removed, then an optimized multiparametric model was established to predict mJOA. Significant correlations were observed between the Torg-Pavlov ratio...

Journal of child neurology, Jan 15, 2015

Tuberous sclerosis complex is a multisystem genetic syndrome often affecting the central nervous ... more Tuberous sclerosis complex is a multisystem genetic syndrome often affecting the central nervous system. The purpose of the current study was to identify topographical patterns in the distribution specific to epileptogenic (n = 37) and nonepileptogenic (n = 544) tubers throughout the brain for a cohort of 23 tuberous sclerosis complex patients with a history of seizures. Tubers localized to the inferior parietal lobes, middle frontal lobes, middle temporal lobes, or central sulcus regions were associated with a high frequency of epileptogenic tubers. Epileptogenic tubers occurred statistically more frequently within the inferior parietal lobe and within the central sulcus region in children younger than 1 or between 1 and 3 years old, respectively. Results imply seizure activity in tuberous sclerosis complex patients can be associated with the location of cortical tubers.

Neurogenetics, 2015

A 55-year-old female presented with a 6-year history of paresthesias, incontinence, spasticity, a... more A 55-year-old female presented with a 6-year history of paresthesias, incontinence, spasticity, and gait abnormalities. Neuroimaging revealed white matter abnormalities associated with subependymal nodules. Biochemical evaluation noted increased serum C5-DC glutarylcarnitines and urine glutaric and 3-hydroxyglutaric acids. Evaluation of the glutaryl-CoA dehydrogenase (GCDH) gene revealed compound heterozygosity consisting of a novel variant (c.1219C>G; p.Leu407Val) and pathogenic mutation (c.848delT; p.L283fs). Together, these results were consistent with a diagnosis of adult-onset type I glutaric aciduria.

LEARNING OBJECTIVES 1) Demonstrate the various appearances of subarachnoid bleeding, including su... more LEARNING OBJECTIVES 1) Demonstrate the various appearances of subarachnoid bleeding, including subtle and conspicious findings. 2) Review the various etiologies of subarachnoid hemorrhage using a multi-modality approach. ABSTRACT Subarachnoid hemorrhage poses a neurosurgical emergency. As a result, it is essential that it is prompty diagnosed, especially in the acute setting. Unfortunately, subtle subarachnoid bleeding may be one of the most difficult radiologic diagnoses. In this exhibit, we present the various imaging findings of subarachnoid hemorrhage, including several examples with extremely subtle clues as to their presence. Residents taking call will especially benefit from these case discussions. We also review the various etiologies of subarachnoid hemorrhage, including aneurysm rupture, arteriovenous malformation, traumatic perimesencephalic venous plexus rupture, venous thrombosis, vasculitis, and neoplasm. A multi-modality approach is used, and CT, MR, and angiographic ...