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Papers by Juan Guzmán-de-villoria

Research paper thumbnail of Brain iron accumulation in dysmetabolic iron overload syndrome with restless legs syndrome

Research paper thumbnail of 1H MR spectroscopy in the assessment of gliomatosis cerebri

AJR. American journal of roentgenology, 2007

Gliomatosis cerebri is a rare brain tumor with a short survival time; for this reason, it is diff... more Gliomatosis cerebri is a rare brain tumor with a short survival time; for this reason, it is difficult to establish the degree of aggressivity in vivo. The MR spectroscopic findings on this tumor often do not agree with choline level. The purpose of this study was to evaluate whether MR spectroscopy can be used to measure tumor choline levels and whether the findings give useful information about tumor growth rate and patient survival time. We performed MRI and 1H MR spectroscopic studies on seven treatment-naive patients with gliomatosis cerebri and on 16 healthy volunteers. We then analyzed the association between survival time and levels of choline (Cho) and N-acetyl aspartate (NAA) normalized to creatine (Cr). The results showed a statistically significant (p = 0.05) inverse relation between Cho/Cr ratio and survival time. In addition, NAA/Cr ratio was significantly lower in the patient group than in the control group (p = 0.001). Cho/Cr ratio measured with MR spectroscopy seems...

Research paper thumbnail of Recurrent acute rhombencephalomyelitis in an adult or neuromyelitis optica? Presentation of a case

Neurología (English Edition), 2012

The lack of accepted homogeneous criteria for the definition of some demyelinating diseases makes... more The lack of accepted homogeneous criteria for the definition of some demyelinating diseases makes diagnostic characterization difficult and limits data interpretation and therapeutic recommendations. Recurrent encephalomyelitis (ADE-R) along with borderline cases of neuromyelitis optica (NMO) are especially controversial. To describe the clinical and radiological evolution of an adult-onset ADE-R versus NMO case throughout 9 years of follow-up. Our patient presented with severe symptoms of rhombencephalomyelitis and the cranial and spinal magnetic resonance imaging (MRI) showed large lesions, with gadolinium enhancement in brainstem and spinal cord, correlating with the clinical picture. Infectious aetiology was excluded, IgG index was normal and NMO antibodies were negative. After treatment with intravenous corticosteroids and plasmapheresis, there was excellent recovery in the acute phase. During follow-up, seven relapses have occurred, mainly in the spinal cord, with good recovery and the same symptomatology, albeit with different severity. Immunosuppressive treatment was introduced since the beginning. Our case shares common features of both ADE-R and NMO, illustrating that diagnostic characterization is not easy in spite of current criteria.

Research paper thumbnail of Estudio de la perfusión cerebral mediante técnicas de susceptibilidad magnética: técnica y aplicaciones

Radiología, 2012

Perfusion MRI makes it possible to evaluate the cerebral microvasculature through changes in sign... more Perfusion MRI makes it possible to evaluate the cerebral microvasculature through changes in signal due to a tracer passing through blood vessels. The most commonly used technique is based on the magnetic susceptibility of gadolinium in T2*-weighted sequences, and the most commonly evaluated parameters are cerebral blood volume, cerebral blood flow, and mean transit time. Diverse technical aspects, like the sequence used, and the dose and speed of contrast material injection, must be taken into account in perfusion MRI studies. It is also essential to consider possible sources of error like contrast material leaks due to changes in the permeability of the blood-brain barrier. The most widely used clinical applications of perfusion MRI include the determination of the degree of aggressiveness of gliomas, the differentiation of some histological types of tumors or pseudotumors, and the evaluation of the penumbral area in acute ischemia.

Research paper thumbnail of Is the Cerebellum the Optimal Reference Region for Intensity Normalization of Perfusion MR Studies in Early Alzheimer’s Disease?

PLoS ONE, 2013

The cerebellum is the region most commonly used as a reference when normalizing the intensity of ... more The cerebellum is the region most commonly used as a reference when normalizing the intensity of perfusion images acquired using magnetic resonance imaging (MRI) in Alzheimer's disease (AD) studies. In addition, the cerebellum provides unbiased estimations with nuclear medicine techniques. However, no reports confirm the cerebellum as an optimal reference region in MRI studies or evaluate the consequences of using different normalization regions. In this study, we address the effect of using the cerebellum, whole-brain white matter, and whole-brain cortical gray matter in the normalization of cerebral blood flow (CBF) parametric maps by comparing patients with stable mild cognitive impairment (MCI), patients with AD and healthy controls. According to our results, normalization by whole-brain cortical gray matter enables more sensitive detection of perfusion abnormalities in AD patients and reveals a larger number of affected regions than data normalized by the cerebellum or whole-brain white matter. Therefore, the cerebellum is not the most valid reference region in MRI studies for early stages of AD. After normalization by whole-brain cortical gray matter, we found a significant decrease in CBF in both parietal lobes and an increase in CBF in the right medial temporal lobe. We found no differences in perfusion between patients with stable MCI and healthy controls either before or after normalization.

Research paper thumbnail of fMRI study of math-gifted adolescents and controls while performing the Raven Progressive Matrices task

NeuroImage, 2009

Other uses, including reproduction and distribution, or selling or licensing copies, or posting t... more Other uses, including reproduction and distribution, or selling or licensing copies, or posting to personal, institutional or third party websites are prohibited.

Research paper thumbnail of Mathematically gifted adolescents use more extensive and more bilateral areas of the fronto-parietal network than controls during executive functioning and fluid reasoning tasks

NeuroImage, 2011

Other uses, including reproduction and distribution, or selling or licensing copies, or posting t... more Other uses, including reproduction and distribution, or selling or licensing copies, or posting to personal, institutional or third party websites are prohibited.

Research paper thumbnail of Cerebral blood flow is an earlier indicator of perfusion abnormalities than cerebral blood volume in Alzheimer’s disease

Journal of Cerebral Blood Flow & Metabolism, 2014

The purpose of this study was to elucidate whether cerebral blood flow (CBF) can better character... more The purpose of this study was to elucidate whether cerebral blood flow (CBF) can better characterize perfusion abnormalities in predementia stages of Alzheimer's disease (AD) than cerebral blood volume (CBV) and whether cortical atrophy is more associated with decreased CBV or with decreased CBF. We compared measurements of CBV, CBF, and mean cortical thickness obtained from magnetic resonance images in a group of healthy controls, patients with mild cognitive impairment (MCI) who converted to AD after 2 years of clinical follow-up (MCI-c), and patients with mild AD. A significant decrease in perfusion was detected in the parietal lobes of the MCI-c patients with CBF parametric maps but not with CBV maps. In the MCI-c group, a negative correlation between CBF values and cortical thickness in the right parahippocampal gyrus suggests an increase in CBF that depends on cortical atrophy in predementia stages of AD. Our study also suggests that CBF deficits appear before CBV deficits in the progression of AD, as CBV abnormalities were only detected at the AD stage, whereas CBF changes were already detected in the MCI stage. These results confirm the hypothesis that CBF is a more sensitive parameter than CBV for perfusion abnormalities in MCI-c patients.

Research paper thumbnail of White matter microstructure correlates of mathematical giftedness and intelligence quotient

Human Brain Mapping, 2014

Recent functional neuroimaging studies have shown differences in brain activation between mathema... more Recent functional neuroimaging studies have shown differences in brain activation between mathematically gifted adolescents and controls. The aim of this study was to investigate the relationship between mathematical giftedness, intelligent quotient (IQ), and the microstructure of white matter tracts in a sample composed of math-gifted adolescents and aged-matched controls. Math-gifted subjects were selected through a national program based on detecting enhanced visuospatial abilities and creative thinking. We used diffusion tensor imaging to assess white matter microstructure in neuroanatomical connectivity. The processing included voxel-wise and region of interest-based analyses of the fractional anisotropy (FA), a parameter which is purportedly related to white matter microstructure. In a whole-sample analysis, IQ showed a significant positive correlation with FA, mainly in the corpus callosum, supporting the idea that efficient information transfer between hemispheres is crucial for higher intellectual capabilities. In addition, math-gifted adolescents showed increased FA (adjusted for IQ) in white matter tracts connecting frontal lobes with basal ganglia and parietal regions. The enhanced anatomical connectivity observed in the forceps minor and splenium may underlie the greater fluid reasoning, visuospatial working memory, and creative capabilities of these children. Hum Brain Mapp 00:000-000, callosum; fronto-parietal; white matter r r r Navas-S anchez et al. r r 2 r r Navas-S anchez et al. r r 6 r r Navas-S anchez et al. r r 10 r r White Matter Microstructure r r 11 r

Research paper thumbnail of 1H MR Spectroscopy in the Assessment of Gliomatosis Cerebri

American Journal of Roentgenology, 2007

Gliomatosis cerebri is a rare brain tumor with a short survival time; for this reason, it is diff... more Gliomatosis cerebri is a rare brain tumor with a short survival time; for this reason, it is difficult to establish the degree of aggressivity in vivo. The MR spectroscopic findings on this tumor often do not agree with choline level. The purpose of this study was to evaluate whether MR spectroscopy can be used to measure tumor choline levels and whether the findings give useful information about tumor growth rate and patient survival time. We performed MRI and 1H MR spectroscopic studies on seven treatment-naive patients with gliomatosis cerebri and on 16 healthy volunteers. We then analyzed the association between survival time and levels of choline (Cho) and N-acetyl aspartate (NAA) normalized to creatine (Cr). The results showed a statistically significant (p = 0.05) inverse relation between Cho/Cr ratio and survival time. In addition, NAA/Cr ratio was significantly lower in the patient group than in the control group (p = 0.001). Cho/Cr ratio measured with MR spectroscopy seems to be related to survival time, possibly explaining the inconsistent findings previously reported for this parameter.

Research paper thumbnail of Neuroimage in Alzheimer's disease: Results after plasma exchange with Human Albumin Grifols®

Alzheimer's & Dementia, 2010

... Affiliations. Clínica Corachán, Barcelona, Spain. ,; Gustavo Torres: Affiliations. Clínica Co... more ... Affiliations. Clínica Corachán, Barcelona, Spain. ,; Gustavo Torres: Affiliations. Clínica Corachán, Barcelona, Spain. ,; Ángel Bittini: Affiliations. Hospital Universitario Gregorio Marañón, Madrid, Spain. ,; Juan Guzmán de Villoria: Affiliations. ...

Research paper thumbnail of Brain iron accumulation in dysmetabolic iron overload syndrome with restless legs syndrome

Research paper thumbnail of 1H MR spectroscopy in the assessment of gliomatosis cerebri

AJR. American journal of roentgenology, 2007

Gliomatosis cerebri is a rare brain tumor with a short survival time; for this reason, it is diff... more Gliomatosis cerebri is a rare brain tumor with a short survival time; for this reason, it is difficult to establish the degree of aggressivity in vivo. The MR spectroscopic findings on this tumor often do not agree with choline level. The purpose of this study was to evaluate whether MR spectroscopy can be used to measure tumor choline levels and whether the findings give useful information about tumor growth rate and patient survival time. We performed MRI and 1H MR spectroscopic studies on seven treatment-naive patients with gliomatosis cerebri and on 16 healthy volunteers. We then analyzed the association between survival time and levels of choline (Cho) and N-acetyl aspartate (NAA) normalized to creatine (Cr). The results showed a statistically significant (p = 0.05) inverse relation between Cho/Cr ratio and survival time. In addition, NAA/Cr ratio was significantly lower in the patient group than in the control group (p = 0.001). Cho/Cr ratio measured with MR spectroscopy seems...

Research paper thumbnail of Recurrent acute rhombencephalomyelitis in an adult or neuromyelitis optica? Presentation of a case

Neurología (English Edition), 2012

The lack of accepted homogeneous criteria for the definition of some demyelinating diseases makes... more The lack of accepted homogeneous criteria for the definition of some demyelinating diseases makes diagnostic characterization difficult and limits data interpretation and therapeutic recommendations. Recurrent encephalomyelitis (ADE-R) along with borderline cases of neuromyelitis optica (NMO) are especially controversial. To describe the clinical and radiological evolution of an adult-onset ADE-R versus NMO case throughout 9 years of follow-up. Our patient presented with severe symptoms of rhombencephalomyelitis and the cranial and spinal magnetic resonance imaging (MRI) showed large lesions, with gadolinium enhancement in brainstem and spinal cord, correlating with the clinical picture. Infectious aetiology was excluded, IgG index was normal and NMO antibodies were negative. After treatment with intravenous corticosteroids and plasmapheresis, there was excellent recovery in the acute phase. During follow-up, seven relapses have occurred, mainly in the spinal cord, with good recovery and the same symptomatology, albeit with different severity. Immunosuppressive treatment was introduced since the beginning. Our case shares common features of both ADE-R and NMO, illustrating that diagnostic characterization is not easy in spite of current criteria.

Research paper thumbnail of Estudio de la perfusión cerebral mediante técnicas de susceptibilidad magnética: técnica y aplicaciones

Radiología, 2012

Perfusion MRI makes it possible to evaluate the cerebral microvasculature through changes in sign... more Perfusion MRI makes it possible to evaluate the cerebral microvasculature through changes in signal due to a tracer passing through blood vessels. The most commonly used technique is based on the magnetic susceptibility of gadolinium in T2*-weighted sequences, and the most commonly evaluated parameters are cerebral blood volume, cerebral blood flow, and mean transit time. Diverse technical aspects, like the sequence used, and the dose and speed of contrast material injection, must be taken into account in perfusion MRI studies. It is also essential to consider possible sources of error like contrast material leaks due to changes in the permeability of the blood-brain barrier. The most widely used clinical applications of perfusion MRI include the determination of the degree of aggressiveness of gliomas, the differentiation of some histological types of tumors or pseudotumors, and the evaluation of the penumbral area in acute ischemia.

Research paper thumbnail of Is the Cerebellum the Optimal Reference Region for Intensity Normalization of Perfusion MR Studies in Early Alzheimer’s Disease?

PLoS ONE, 2013

The cerebellum is the region most commonly used as a reference when normalizing the intensity of ... more The cerebellum is the region most commonly used as a reference when normalizing the intensity of perfusion images acquired using magnetic resonance imaging (MRI) in Alzheimer's disease (AD) studies. In addition, the cerebellum provides unbiased estimations with nuclear medicine techniques. However, no reports confirm the cerebellum as an optimal reference region in MRI studies or evaluate the consequences of using different normalization regions. In this study, we address the effect of using the cerebellum, whole-brain white matter, and whole-brain cortical gray matter in the normalization of cerebral blood flow (CBF) parametric maps by comparing patients with stable mild cognitive impairment (MCI), patients with AD and healthy controls. According to our results, normalization by whole-brain cortical gray matter enables more sensitive detection of perfusion abnormalities in AD patients and reveals a larger number of affected regions than data normalized by the cerebellum or whole-brain white matter. Therefore, the cerebellum is not the most valid reference region in MRI studies for early stages of AD. After normalization by whole-brain cortical gray matter, we found a significant decrease in CBF in both parietal lobes and an increase in CBF in the right medial temporal lobe. We found no differences in perfusion between patients with stable MCI and healthy controls either before or after normalization.

Research paper thumbnail of fMRI study of math-gifted adolescents and controls while performing the Raven Progressive Matrices task

NeuroImage, 2009

Other uses, including reproduction and distribution, or selling or licensing copies, or posting t... more Other uses, including reproduction and distribution, or selling or licensing copies, or posting to personal, institutional or third party websites are prohibited.

Research paper thumbnail of Mathematically gifted adolescents use more extensive and more bilateral areas of the fronto-parietal network than controls during executive functioning and fluid reasoning tasks

NeuroImage, 2011

Other uses, including reproduction and distribution, or selling or licensing copies, or posting t... more Other uses, including reproduction and distribution, or selling or licensing copies, or posting to personal, institutional or third party websites are prohibited.

Research paper thumbnail of Cerebral blood flow is an earlier indicator of perfusion abnormalities than cerebral blood volume in Alzheimer’s disease

Journal of Cerebral Blood Flow & Metabolism, 2014

The purpose of this study was to elucidate whether cerebral blood flow (CBF) can better character... more The purpose of this study was to elucidate whether cerebral blood flow (CBF) can better characterize perfusion abnormalities in predementia stages of Alzheimer's disease (AD) than cerebral blood volume (CBV) and whether cortical atrophy is more associated with decreased CBV or with decreased CBF. We compared measurements of CBV, CBF, and mean cortical thickness obtained from magnetic resonance images in a group of healthy controls, patients with mild cognitive impairment (MCI) who converted to AD after 2 years of clinical follow-up (MCI-c), and patients with mild AD. A significant decrease in perfusion was detected in the parietal lobes of the MCI-c patients with CBF parametric maps but not with CBV maps. In the MCI-c group, a negative correlation between CBF values and cortical thickness in the right parahippocampal gyrus suggests an increase in CBF that depends on cortical atrophy in predementia stages of AD. Our study also suggests that CBF deficits appear before CBV deficits in the progression of AD, as CBV abnormalities were only detected at the AD stage, whereas CBF changes were already detected in the MCI stage. These results confirm the hypothesis that CBF is a more sensitive parameter than CBV for perfusion abnormalities in MCI-c patients.

Research paper thumbnail of White matter microstructure correlates of mathematical giftedness and intelligence quotient

Human Brain Mapping, 2014

Recent functional neuroimaging studies have shown differences in brain activation between mathema... more Recent functional neuroimaging studies have shown differences in brain activation between mathematically gifted adolescents and controls. The aim of this study was to investigate the relationship between mathematical giftedness, intelligent quotient (IQ), and the microstructure of white matter tracts in a sample composed of math-gifted adolescents and aged-matched controls. Math-gifted subjects were selected through a national program based on detecting enhanced visuospatial abilities and creative thinking. We used diffusion tensor imaging to assess white matter microstructure in neuroanatomical connectivity. The processing included voxel-wise and region of interest-based analyses of the fractional anisotropy (FA), a parameter which is purportedly related to white matter microstructure. In a whole-sample analysis, IQ showed a significant positive correlation with FA, mainly in the corpus callosum, supporting the idea that efficient information transfer between hemispheres is crucial for higher intellectual capabilities. In addition, math-gifted adolescents showed increased FA (adjusted for IQ) in white matter tracts connecting frontal lobes with basal ganglia and parietal regions. The enhanced anatomical connectivity observed in the forceps minor and splenium may underlie the greater fluid reasoning, visuospatial working memory, and creative capabilities of these children. Hum Brain Mapp 00:000-000, callosum; fronto-parietal; white matter r r r Navas-S anchez et al. r r 2 r r Navas-S anchez et al. r r 6 r r Navas-S anchez et al. r r 10 r r White Matter Microstructure r r 11 r

Research paper thumbnail of 1H MR Spectroscopy in the Assessment of Gliomatosis Cerebri

American Journal of Roentgenology, 2007

Gliomatosis cerebri is a rare brain tumor with a short survival time; for this reason, it is diff... more Gliomatosis cerebri is a rare brain tumor with a short survival time; for this reason, it is difficult to establish the degree of aggressivity in vivo. The MR spectroscopic findings on this tumor often do not agree with choline level. The purpose of this study was to evaluate whether MR spectroscopy can be used to measure tumor choline levels and whether the findings give useful information about tumor growth rate and patient survival time. We performed MRI and 1H MR spectroscopic studies on seven treatment-naive patients with gliomatosis cerebri and on 16 healthy volunteers. We then analyzed the association between survival time and levels of choline (Cho) and N-acetyl aspartate (NAA) normalized to creatine (Cr). The results showed a statistically significant (p = 0.05) inverse relation between Cho/Cr ratio and survival time. In addition, NAA/Cr ratio was significantly lower in the patient group than in the control group (p = 0.001). Cho/Cr ratio measured with MR spectroscopy seems to be related to survival time, possibly explaining the inconsistent findings previously reported for this parameter.

Research paper thumbnail of Neuroimage in Alzheimer's disease: Results after plasma exchange with Human Albumin Grifols®

Alzheimer's & Dementia, 2010

... Affiliations. Clínica Corachán, Barcelona, Spain. ,; Gustavo Torres: Affiliations. Clínica Co... more ... Affiliations. Clínica Corachán, Barcelona, Spain. ,; Gustavo Torres: Affiliations. Clínica Corachán, Barcelona, Spain. ,; Ángel Bittini: Affiliations. Hospital Universitario Gregorio Marañón, Madrid, Spain. ,; Juan Guzmán de Villoria: Affiliations. ...