Marco Antonio Gutierrez

A voxel-based investigation of regional cerebral blood flow abnormalities in obsessive–compulsive disorder using single photon emission computed tomography (SPECT)

Several functional imaging studies have reported abnormalities of the orbitofrontal and anterior cingulate cortices, striatum and thalamus in obsessive-compulsive disorder (OCD). These studies have often been limited by small patient samples and image analysis methods that rely on region-of-interest (ROI) approaches. We have assessed resting regional cerebral blood flow with 99mTc-ECD SPECT in 26 unmedicated OCD patients and 22 healthy control subjects using the voxel-based Statistical Parametric Mapping method for data analysis. We found a significantly reduced ECD uptake in OCD patients relative to the control subjects in the right lateral orbitofrontal cortex, and in the left dorsal anterior cingulate cortex (P<0.001 two-tailed, uncorrected for multiple comparisons). There were significant positive correlations in the OCD group between the ECD uptake in the left lateral orbitofrontal cortex and ratings for obsessive-compulsive symptoms (OCS), and between the ECD uptake in the right medial orbitofrontal cortex and the ratings for both OCS and depressive symptoms. There were also unpredicted significant ECD uptake increases in the cerebellum in OCD patients, as well as a negative correlation between posterior cingulate ECD uptake and OCS severity (P<0.05, corrected for multiple testing). These results implicate specific subregions of the orbitofrontal and anterior cingulate cortices in the pathophysiology of OCD, as well as suggesting the involvement of other areas not usually included in ROI-based imaging studies. With the incorporation of voxel-based methods and the use of large patient samples, rCBF-SPECT studies may continue to provide valuable information about the functional anatomy of OCD.

Automatic measurement of carotid diameter and wall thickness in ultrasound images

Carotid vessel ultrasound imaging is a reliable noninvasive technique to measure the arterial morphology. Lumen Diameter (LD), intima-media thickness (IMT) of the far wall, and plaque presence can be reliably determined using B-mode ultrasound. In order to measure the carotid IMT as well as any other more complex quantitative indices of vessel morphology, it is necessary to identify lumen-intima and media-adventitia borders in the ultrasound images. In this paper we describe an automatic approach to measure LD and IMT based on an active contour technique improved by a multiresolution analysis. The measurements of LD and IMT were compared to manual tracing of the vessels border in terms of coefficients of variability (CV) and correlation (R). The results have shown that the method is a reliable and reproducible way of assessing the LD and far wall IMT in the carotid artery.

Mobile health in emerging countries: A survey of research initiatives in Brazil

OBJECTIVE To conduct a comprehensive survey of mobile health (mHealth) research initiatives in Brazil, discussing current challenges, gaps, opportunities and tendencies. METHODS Systematic review of publicly available electronic documents related to mHealth, including scientific publications, technical reports and descriptions of commercial products. Specifically, 42 projects are analyzed and classified according to their goals. This analysis considers aspects such as security features provided (if any), the health condition that are focus of attention, the main providers involved in the projects development and deployment, types of devices used, target users, where the projects are tested and/or deployed, among others. RESULTS The study shows a large number (86%) of mHealth solutions focused on the following categories: health surveys, surveillance, patient records and monitoring. Meanwhile, treatment compliance, awareness raising and decision support systems are less explored. The main providers of solutions are the universities (56%) and health units (32%), with considerable cooperation between such entities. Most applications have physicians (55%) and Community Health Agents (CHAs) (33%) as targeted users, the latter being important elements in nation-wide governmental health programs. Projects focused on health managers, however, are a minority (5%). The majority of projects do not focus on specific diseases but rather general health (57%), although solutions for hearth conditions are reasonably numerous (21%). Finally, the lack of security mechanisms in the majority of the surveyed solutions (52%) may hinder their deployment in the field due to the lack of compliance with general regulations for medical data handling. CONCLUSION There are currently many mHealth initiatives in Brazil, but some areas have not been much explored, such as solutions for treatment compliance and awareness raising, as well as decision support systems. Another research trend worth exploring refers to creating interoperable security mechanisms, especially for widely explored mHealth categories such as health surveys, patient records and monitoring. Challenges for the expansion of mHealth solutions, both in number and coverage, include the further involvement of health managers in the deployment of such solutions and in coordinating efforts among health and research institutions interested in the mHealth trend, possibly exploring the widespread presence of CHAs around the country as users of such technology.

Managing Medical Images and Clinical Information: InCor's Experience

Patients usually get medical assistance in several clinics and hospitals during their lifetime, archiving vital information in a dispersed way. Clearly, a proper patient care should take into account that information in order to check for incompatibilities, avoid unnecessary exams, and get relevant clinical history. The Heart Institute (InCor) of Satildeo Paulo, Brazil, has been committed to the goal of integrating all exams and clinical information within the institution and other hospitals. Since InCor is one of the six institutes of the University of Satildeo Paulo Medical School and each institute has its own information system, exchanging information among the institutes is also a very important aspect that has been considered. In the last few years, a system for transmission, archiving, retrieval, processing, and visualization of medical images integrated with a hospital information system has been successfully created and constitutes the InCors electronic patient record (EPR). This work describes the experience in the effort to develop a functional and comprehensive EPR, which includes laboratory exams, images (static, dynamic, and three dimensional), clinical reports, documents, and even real-time vital signals. A security policy based on a contextual role-based access control model was implemented to regulate users access to EPR. Currently, more than 10 TB of digital imaging and communications in medicine (DICOM) images have been stored using the proposed architecture and the EPR stores daily more than 11 GB of integrated data. The proposed storage subsystem allows 6 months of visibility for rapid retrieval and more than two years for automatic retrieval using a jukebox. This paper addresses also a prototype for the integration of distributed and heterogeneous EPR

Assessment of carotid diameter and wall thickness in ultrasound images using active contours improved by a multiresolution technique

Carotid vessel ultrasound imaging is a reliable non-invasive technique to measure the arterial morphology. Vessel diameter, intima-media thickness (IMT) of the far wall and plaque presence can be reliably determined using B-mode ultrasound. In this paper we describe a semi-automatic approach to measure artery diameter and IMT based on an active contour technique improved by a multiresolution analysis. The operator selects a region-of-interest (ROI) in a series of carotid images obtained from B-mode ultrasound. This set of images is convolved with the corresponding partial derivatives of the Gaussian filter. The filter response is used to compute a 2D gradient magnitude image in order to refine the vessels boundaries. Using an active contour technique the vessels border is determined automatically. The near wall media-adventitia (NWMA), far wall media-adventitia (FWMA) and far wall lumen-intima (FWLI) borders are obtained by a least-square fitting of the active contours result. The distance between NWMA and FWLI (vessel diameter) and between FWLI and FWMA (far wall intima-media thickness) are obtained for all images and the mean value is computed during systole and diastole. The proposed method is a reliable and reproducible way of assessing the vessel diameter and far wall intima-media thickness of the carotid artery.

Computing optical flow in cardiac images for 3D motion analysis

Optical flow measurement is a well established image processing technique for the analysis of motion. Optical flow is computed as the solution to a linear algebraic equation system whose coefficient matrix is formed by a combination of temporal and spatial image derivatives The coefficient matrix is sparse and usually very large, as its dimension is twice that of the original 2D images. Here the authors describe the steps required to build an optical flow linear system for 3D space. They assess the use of the arithmetic reconstruction technique (ART) to solve the huge linear system involved in estimating 3D optical flow. ART does not require any special matrix structure apart from a high degree of sparseness. It has been extensively used in tomographic image reconstruction and has proven to be effective when solving large systems.<<ETX>>

Estimation of myocardial kinetic energy in gated SPECT images

Conventional methods for the analysis of left ventricle (LV) wall motion are based on 2D images with many hardly fulfilled assumptions. The methods in use today suffer from several problems as they do not take into account three-dimensional (3D) information that can be provided by image modalities such as nuclear medicine and MRI. This work describes a method to quantify 3D LV motion by a series of 3D velocity vector fields that are computed automatically for each voxel on the sequence of 16 cardiac volumes. Using the velocity it is possible to estimate the kinetic energy for each voxel. The integration of this quantity over the LV muscle gives an estimate of the left ventricle wall kinetic energy. A curve representing the myocardial kinetic energy can be plotted and used as an indicator of cardiac conditions. The proposed method was applied to the study of normal and abnormal hearts. Results have shown that the curve pattern for hearts with infarct differs substantially from a normal heart.

3-D analysis of left ventricle dynamics

Describes a method which quantifies 3D LV motion by means of the optical flow technique extended to the voxel space. Motion is represented by a 3D velocity vector field which is computed for each voxel on the series of cardiac volumes. The algorithm developed has two steps: (1) the spatial and temporal derivatives of the 3D image brightness are computed, after the cardiac volumes have been convolved with a symmetrical Gaussian function filter; (2) The optical flow is computed as the solution to a linear algebraic system of equations whose coefficients are determined by the derivatives that were computed in (1). The velocity vector field estimated from a sequence of 3D images has been computed for normal and infarcted hearts obtained at InCors Nuclear Medicine Department.<<ETX>>

Automatic quantification of three-dimensional kinetic energy in gated myocardial perfusion single-photon-emission computerized tomography improved by a multiresolution technique

The visualization of the left ventricle (LV) motion in gated single-photon-emission computerized tomography (SPECT) studies is complicated by the fact that 3-D density images cannot be directly presented using common display devices. A number of techniques, most of them concerned with visualization, have been developed to aid in the classification of the images. However, it has been shown that interpretation of LV images by strictly visual techniques is sub- ject to errors and inconsistencies. For this reason, assistance in diagnosis can be improved only through the development of auto- matic or semiautomatic methods to analyze and to quantify LV pa- rameters. We propose an automatic method to estimate the myocar- dial kinetic energy directly from gated SPECT sequences based on the optical flow method refined with a multiresolution technique. Specifically, the method quantifies the LV motion by a series of 3-D velocity vector fields computed for each voxel on the sequence of images. The 3-D velocity vector field obtained is used to estimate the kinetic energy, which may be an indication of the cardiac condi- tion. The proposed procedure was applied to a group of volunteers and the cardiac condition of each subject studied by taking the re- lation between the maximum and minimum values of kinetic energy observed during the cardiac cycle.

Integrating Medical Images and Clinical Information

The Heart Institute (InCor) of Sao Paulo has been committed to the goal of integrating all clinical information within the institution. In the last few years, InCor has successfully created a system for transmission, archiving, retrieval, processing and visualization of Medical Images and also a Hospital Information System that stores the administrative and clinical information. These integrated subsystems form InCors Electronic Patient Record (EPR). This work describes the experience in the effort to develop a functional and comprehensive EPR, which includes access control, lab exams, images (static, dynamic and 3D), clinical reports, documents and even real-time vital signals. Currently, more than 13TB of DICOM images have been stored using the proposed architecture. The EPR stores more than 5 GB/day of integrated data and presents more than 1400 hits per day. The proposed storage subsystem allows six months of visibility for rapid retrieval and more than two years for automatic retrieval using a jukebox.