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Biomedical subjects

Mauricio Castillo

Publications and source records attributed to Mauricio Castillo.

At least 19 recordsLinked to original sources
PubMed2007

Cerebral blood volume measurements and proton MR spectroscopy in grading of oligodendroglial tumors.

OBJECTIVE: The purpose of this study was to determine whether perfusion-weighted imaging (PWI) and proton MR spectroscopy (MRS) are useful in differentiating high- and low-grade oligodendroglial tumors. MATERIALS AND METHODS: PWI and MRS studies of 22 patients with histologically proven oligodendroglioma or oligoastrocytoma (13 low-grade and nine anaplastic tumors) were retrospectively reviewed. PWI of 14 subjects was performed with a dynamic contrast-enhanced susceptibility-weighted echo-planar technique. Intratumoral relative cerebral blood volume ratio was calculated and normalized to the same value in contralateral normal-appearing white matter. Multivoxel MRS was performed with a point-resolved spectroscopy sequence at a TE of 135 milliseconds in 20 patients and with the addition of a TE of 30 seconds in 17 patients. MRS data were expressed as intratumoral metabolite ratios (choline to creatine [Cho/Cr], choline to N-acetyl aspartate, N-acetyl aspartate to creatine, and myoinositol to creatine). RESULTS: Relative cerebral blood volume ratios were significantly different (p = 0.004) between low-grade (1.61 +/- 1.20) and high-grade tumors (5.45 +/- 1.96). The optimal relative cerebral blood volume ratio cutoff value in identification of anaplastic oligodendroglial tumors was 2.14. Analysis of MRS data showed significantly higher Cho/Cr ratios (p = 0.002) in high-grade than in low-grade tumors. A Cho/Cr ratio cutoff value of 2.33 had the highest accuracy in identification of high-grade tumors. CONCLUSION: Relative cerebral blood volume measurement and MRS are helpful in differentiating low-grade from anaplastic oligodendroglial tumors.

Adult↗
PubMed2006

Clinical role of proton magnetic resonance spectroscopy in oncology: brain, breast, and prostate cancer.

Standardised proton magnetic resonance spectroscopic imaging (MRSI) was initially developed for routine in-situ clinical assessment of human brain tumours, and its use was later extended for examination of prostate and breast cancers. MRSI coupled with both routine and functional MRI techniques provides more detailed information about a tumour's location and extent of its infiltration than any other modality alone. Information obtained by adding MRSI data to anatomical and functional MRI findings aid in clinical management decisions (such as watchful waiting vs immediate intervention). In this Review, we discuss the current status of proton MRSI, with emphasis on its clinical use to map the location and extent of tumour processes for spectroscopic image-guided biopsy procedures and to monitor treatment paradigms for brain, prostate, and breast cancer.

Brain Neoplasms↗
PubMed2005

Imaging in acute stroke.

Stroke is a syndrome characterized by a sudden neurological deficit caused by intracranial hemorrhage or ischemia. Computed tomography (CT) maintains a primary role in the evaluation of patients with acute stroke. The optimal magnetic resonance imaging (MRI) protocol in acute stroke includes diffusion-weighted imaging (DWI) to show acute ischemic lesion and MR perfusion study to estimate brain perfusion. Careful selection of patients for a thrombolytic therapy is crucial to improve safety and efficacy.

Algorithms↗
PubMed2005

Magnetic resonance imaging findings in substance abuse: alcohol and alcoholism and syndromes associated with alcohol abuse.

Alcohol abuse is common among the population and results in significant diseases that shorten life span. Ethanol may result in chronic brain changes such as atrophy but may also result in neurologic disease that may be acute or chronic and sometimes life threatening. Accompanying vitamin deficiencies may lead to Wernicke's encephalopathy and changes in serum osmosis may lead to several acute demyelinating disorders. In addition, pregnant women who consume alcohol place their babies at high risk for the fetal alcohol syndrome. In this article we review these disorders and emphasize their imaging features.

Alcohol-Induced Disorders, Nervous System↗
PubMed2005

Pituitary gland: development, normal appearances, and magnetic resonance imaging protocols.

In this article, I will review the normal anatomy of the pituitary gland starting with a brief review of aspects of its origin and development that are pertinent to radiologists. The anatomy of the anterior and posterior lobes will be addressed as will be that of the surrounding structures and of the vascular structures of the gland. Radiologists need to be familiar with the normal magnetic resonance imaging appearance of the gland and the changes that it undergoes throughout life. The normal patterns of contrast enhancement by the gland are described. Normal pituitary variations and incidental conditions are discussed, and the article finishes by describing appropriate imaging protocols.

Adolescent↗
PubMed2005

Congenital pathology of the pituitary gland and parasellar region.

The adenohypophysis and neurohypophysis originate from the combination of 2 events occurring during the fourth week of life, the development of Rathke pouch and of a neuroectodermal evagination of tissue from the floor of the diencephalon. Congenital pathology of the pituitary gland and parasellar regions derives from abnormalities of these coordinated events. In this article, we review the pathogenesis, clinical presentation, and imaging features of common and rare congenital disorders of the region of the sella turcica.

Humans↗
PubMed2005

Nonadenomatous tumors of the pituitary and sella turcica.

While pituitary adenomas make up over 90% of all sellar masses, there are a number of less known tumors, both malignant and benign, which may arise within the sella turcica. These include relatively common tumors such as meningiomas and craniopharyngiomas, as well as extremely rare tumors such as pituitary astrocytomas and granular cell tumors. Unfortunately, many of these tumors lack characteristic imaging features, often making it extremely difficult to distinguish them by imaging alone from the more common pituitary adenoma. In this article, we review several nonadenomatous tumors of the sella, with a focus on their clinical features and typical MR imaging characteristics.

Craniopharyngioma↗
PubMed2005

Imaging the anatomy of the brachial plexus: review and self-assessment module.

OBJECTIVE: The educational objectives of this continuing medical education activity are to describe the normal anatomy of the brachial plexus, to name the most common symptoms associated with a brachial plexopathy, to describe the most common imaging findings resulting from trauma to the brachial plexus, to describe the imaging manifestations of common neoplasias affecting the brachial plexus, and to also describe the imaging findings and symptoms related to irradiation-induced brachial plexopathies. CONCLUSION: In this article, I have illustrated and described the normal anatomy of the brachial plexus; the most common symptoms related to brachial plexopathy; and imaging findings related to trauma, tumors, and irradiation affecting the brachial plexus.

Adult↗
PubMed2005

Hemodynamic and permeability changes in posterior reversible encephalopathy syndrome measured by dynamic susceptibility perfusion-weighted MR imaging.

BACKGROUND AND PURPOSE: The physiological mechanism that gives rise to posterior reversible encephalopathy syndrome (PRES) is currently unknown. We sought to better understand the mechanism of the edema formation in PRES and specifically hypothesized that this edema is caused by increased vascular permeability. METHODS: Eight consecutive patients with PRES who had been studied by using perfusion MR imaging were retrospectively identified. Perfusion images were obtained using a gradient-echo echo planar sequence with contrast enhancement. Measures of apparent diffusion coefficient (ADC), cerebral blood volume (CBV), cerebral blood flow (CBF), mean transit time (MTT) and vascular permeability (K2) were calculated in the affected posterior brain areas and normalized to values obtained in unaffected anterior brain. These values were compared with those found in healthy subjects. RESULTS: Regions of interest within the posterior affected brain indicated a significant increase in ADC values in all but one patient, a significant decrease in CBV and CBF values in all patients with PRES (average 30% of control), variable changes in MTT, and no measurable change in K2. CONCLUSION: The decrease in both CBV and CBF in PRES supports the theory of autoregulatory vasoconstriction; changes in K2 were not detected.

Adolescent↗
PubMed2005

Diffusion-tensor MR imaging of the brain in human immunodeficiency virus-positive patients.

BACKGROUND AND PURPOSE: There is early evidence that diffusion-tensor imaging (DTI) is useful in demonstrating subtle white matter alterations in different diseases of brain. We hypothesize that DTI in several brain regions in human immunodeficiency virus-positive (HIV+) patients is useful in the early detection of HIV-related brain injury. METHODS: MR imaging and DTI were performed in 60 HIV+ patients and in 30 controls. Fractional anisotropy (FA) and apparent diffusion coefficient (ADC; mm/s(2)) maps were generated and coregistered on T2-weighted images. Regions of interest were placed in the splenium and genu of the callosum, the frontal white matter, and the hippocampus. HIV+ patients were divided into those whose CD4 count were <250 cells/mm(3) or >250 cells/mm(3). According to plasma viral loads, patients were divided into those whose viral loads were <50 copies/mL, 50-100,000 copies/mL, or >100,000 copies/mL. RESULTS: Statistically significant decrease of FA was found in the genu of the corpus callosum in HIV+ patients compared with controls. FA was reduced in the frontal white matter and hippocampi in HIV+ patients compared with controls. Differences, however, were not statistically significant. No statistically significant differences were found between the HIV+ groups for FA of the splenium or between these groups and the controls. ADC values were significantly increased in the genu of HIV+ patients when compared with controls and were also increased in other locations, but without statistical significance. CONCLUSION: As used in this study, DTI was not helpful in identifying patients with early HIV infection.

Adolescent↗
PubMed2004

Brain MRI findings in patients with mucopolysaccharidosis types I and II and mild clinical presentation.

Our objective was to determine the brain magnetic resonance imaging (MRI) abnormalities in a selected group of patients with mucopolysaccharidosis (MPS) types I and II who had only mild clinical manifestations. We retrospectively assessed MRI brain studies in 18 patients with MPS (type I: 6 and type II: 12). We evaluated abnormal signal intensity in the white matter, widening of the cortical sulci, size of the supratentorial ventricles, dilatation of the perivascular spaces (PVS) and enlargement of the subarachnoid spaces. We observed a broad spectrum of findings, and despite severely abnormal MRI studies, no patients had mental retardation. We also observed that dilated PVS, previously believed to be caused by macroscopic deposition of the mucopolysaccharides, had an appearance similar to cerebrospinal fluid (CSF) in all MRI sequences performed, even in FLAIR and trace diffusion weighted images. Based on our results, we believe that with the exception of white matter abnormalities and brain atrophy, all other findings may be related to abnormal resorption of CSF, and there is no relationship between the imaging and clinical manifestations of the disease.

Adolescent↗