Gonzalo Rojas's Publications List

Prefrontal Cortex and Control of Behavior – Evidence from Neuropsychological Studies.

2010-02-04T04:03:29Z

"Few subjects in neurology have been associated with as much and paradox as the behavioral afflictions of the prefrontal cortex" (Marsel Mesulam, 2002). The case of Phineas Gage, the first well-described patient with a prefrontal lesion, revealed that this sort of lesion could cause severe trouble in everyday life and a profound disturbance of personality. Disturbances of patients with prefrontal...

A Slachevsky, P Reyes, G Rojas, and JR Silva (2009) From Attention to Goal-Directed Behavior. Neurodynamical, Methodological and Clinical Trends.

Semi-automated assessment of left ventricular mass using transaxial Tc-99m Sestamibi SPECT imaging.

2010-02-05T01:01:48Z

The "left ventricular mass" (LVM) using Tc-99m Sestamibi SPECT imaging may be a useful parameter to quantitatively assess the left ventricle and hence its function. The LVM was determined without reorienting the images along the long axis of the left ventricle. A comparison with reoriented SPECT images was then performed. The LVM showed the expected variations among different pathological heart co...

G Rojas, U Raff, P Gonzalez, R Jaimovich, J C Quintana (2009) Comput Med Imaging Graph 33: 4 247-255

Regularization of diffusion tensor images.

2010-02-05T00:41:27Z

Jaime Cisternas, Takeshi Asahi, Marcelo Gállvez, Gonzalo Rojas-Costa (2008) ISBI : From Nano to Macro, Paris, France, May 14-17, 2008 935-938

Proceedings of the 2008 IEEE International Symposium on Biomedical Imaging : From Nano to Macro, Paris, France, May 14-17, 2008

2010-02-05T00:38:10Z

(2008) :

Image fusion in neuroradiology: three clinical examples including MRI of Parkinson disease.

2010-02-05T01:03:39Z

Image data fusion has been developed over the last decade as an important additional visual diagnostic tool to integrate the growing amount of imaging data obtained from different medical imaging modalities. The overwhelming amount of digital information calls for data consolidation to improve clinical treatment strategies based upon anatomical and physiological imaging. Three different low level ...

G M Rojas, U Raff, J C Quintana, I Huete, M Hutchinson (2007) Comput Med Imaging Graph 31: 1 17-27

Inversion recovery MRI in idiopathic Parkinson disease is a very sensitive tool to assess neurodegeneration in the substantia nigra: preliminary investigation.

2010-02-05T02:25:02Z

RATIONALE AND OBJECTIVES: Segmented inversion recovery (IR) ratio imaging (SIRRIM) has been established as a sensitive tool to assess neurodegeneration of the substantia nigra pars compacta (SN(C)) in patients with idiopathic Parkinson disease (IPD). The obtained results suggest the possibility of magnetic resonance imaging (MRI) as a biological marker for IPD. The strength and a parsimonious anal...

Ulrich Raff, Michael Hutchinson, Gonzalo M Rojas, Isidro Huete (2006) Acad Radiol 13: 6 721-727

Hemodynamic Characterization of Ruptured and Unrupted Cerebral Aneurysms Using Computer Fluid Dynamics

2010-02-05T00:54:11Z

M. Galvez, E. Bravo, A. Valencia, R. Rivera, H. Morales, L. Badilla, G.Sordo, T.Asahi, G. Rojas, M. Peldoza (2006) Neuroradiology. Volume 48, Supplement 2 / septiembre de 2006 1

Use of Turbo GRAPPA Inversion Recovery (IR) Imaging in Parkinson's Disease

2010-02-05T02:27:53Z

Segmented inversion recovery ratio imaging (SIRRIM) was introduced in previous works to investigate selective neurodegeneration in idiopathic Parkinson’s disease. Turbo GRAPPA inversion recovery is now explored to assess neurodegeneration in the substantia nigra.

Gonzalo M. Rojas, Ulrich Raff, Pedro Chaná, Carlos Juri, Isidro Huete, Nelson Lafont, Michael Hutchinson (2006) Magnetom Flash (Siemens Journal) : 1 52-56

Analog gamma camera digitalization computer system

2010-02-04T03:16:06Z

OBJECTIVE: Digitalization of analogue gamma cameras systems, using special acquisition boards in microcomputers and appropriate software for acquisition and processing of nuclear medicine images is described in detail. MATERIAL AND METHODS: Microcomputer integrated systems interconnected by means of a Local Area Network (LAN) and connected to several gamma cameras have been implemented using speci...

G M Rojas, J C Quintana, J Jer, S Astudillo, L Arenas, H Araya (2004) Rev Esp Med Nucl 23: 2 106-113

Computer assessment of neurodegeneration in Parkinson disease using data fusion techniques with MR images.

2010-02-05T02:32:20Z

RATIONALE AND OBJECTIVES: Recently developed MR imaging techniques using inversion recovery are a sensitive tool to identify and quantify morphologic changes in the substantia nigra due to neurodegeneration. Using a semi-automated computer segmentation technique to isolate the substantia nigra pars compacta (SN(c)), we propose a colored image fusion technique to visually assess the sites of damage...

Ulrich Raff, Gonzalo M Rojas, Isidro Huete, Michael Hutchinson (2003) Acad Radiol 10: 9 1036-1044

Lung computed tomography during a lung recruitment maneuver in patients with acute lung injury.

2010-02-05T01:10:00Z

OBJECTIVE: To assess the acute effect of a lung recruitment maneuver (LRM) on lung morphology in patients with acute lung injury (ALI) or acute respiratory distress syndrome (ARDS). PATIENTS: Ten patients with ALI/ARDS on mechanical ventilation. DESIGN: Prospective clinical study. SETTING: Computed tomography (CT) scan facility in a teaching hospital. INTERVENTIONS: An LRM performed by stepwise in...

Guillermo Bugedo, Alejandro Bruhn, Glenn Hernández, Gonzalo Rojas, Cristián Varela, Juan Carlos Tapia, Luis Castillo (2003) Intensive Care Med 29: 2 218-225

Mechanical ventilation to treat acute respiratory distress syndrome secondary to descending necrotizing mediastinitis. Role of dynamic axial computed tomography of the lung

2010-02-04T03:40:35Z

Lung computed tomography (CT) is being used increasingly to assess lung morphology in patients on mechanical ventilation. Lung CT under known levels of airway pressure (dynamic CT) can also assess the response of lung parenchyma to ventilatory therapy. We report a patient with acute respiratory distress syndrome secondary to descending necrotizing mediastinitis, in whom lung dynamic CT oriented ve...

Guillermo Bugedo, Alejandro Bruhn, Glenn Hernández, Gonzalo Rojas, Rodrigo Aparicio, Luis Castillo (2003) Rev Med Chil 131: 2 200-208

Quantitation of T2 lesion load in patients with multiple sclerosis: a novel semiautomated segmentation technique.

2010-02-04T03:16:06Z

RATIONALE AND OBJECTIVES: The authors designed a segmentation technique that requires only minimal operator input at the initial and final supervision stages of segmentation and has computer-driven segmentation as the primary determinant of lesion boundaries. The technique was applied to compute total T2-hyperintense lesion volumes in patients with multiple sclerosis (MS). A semi-automated segment...

U Raff, G M Rojas, M Hutchinson, J H Simon (2000) Acad Radiol 7: 4 237-247

Quantitation of T2 lesion load in multiple sclerosis with magnetic resonance imaging: a pilot study of a probabilistic neural network approach.

2010-02-04T03:16:06Z

RATIONALE AND OBJECTIVES: To quantitate multiple sclerosis (MS) lesions in the brain by using computerized techniques. METHODS: MS lesions from five patients were quantitated with magnetic resonance (MR) imaging by using three approaches: a probabilistic neural network (PNN) approach, a semiautomated method that uses a bifeature space approach with operator intervention at each section, and the "g...

U Raff, P F Vargas, G M Rojas, A L Scherzinger, J H Simon (1997) Acad Radiol 4: 6 431-437

Automated discrimination and quantification of idiopathic pulmonary fibrosis from normal lung parenchyma using generalized fractal dimensions in high-resolution computed tomography images.

2010-02-04T03:16:06Z

RATIONALE AND OBJECTIVES: We computed generalized fractal dimensions for high-resolution computed tomography (HRCT) images to investigate their value in the discrimination and quantification of idiopathic pulmonary fibrosis (IPF) from normal lung parenchyma. METHODS: A probability distribution that was based on the pixel value in each image was used to compute capacity, information, and higher fra...

L H Rodriguez, P F Vargas, U Raff, D A Lynch, G M Rojas, D M Moxley, J D Newell (1995) Acad Radiol 2: 1 10-18