In vivo characterization of the vestibulo-cochlear nerve motion by MRI.

The motion of the vestibulo-cochlear nerve (VCN) was quantified at the level of the cerebello-pontine angle in 28 healthy volunteers enrolled in a prospective study performed on a 3T MRI scanner. A phase contrast MRI (PCMRI) sequence was used. The VCN was divided into a cisternal part and a meatic part, both of which were measured for motion in the cranio-caudal (CC) and antero-posterior (AP) directions. Motion was cardiac-cycle-dependent in these two directions. The meatic VCN motion was delayed compared to the cisternal VCN motion. In the CC direction, the mean amplitude of the cisternal VCN motion was twice larger than the mean amplitude of the meatic VCN motion (0.37+/-0.14 mm versus 0.17+/-0.08 mm). In the AP direction, the mean amplitude of the cisternal VCN was 0.19+/-0.08 mm versus 0.16+/-0.14 mm for the meatic VCN. We used an "oscillating string" to explain the VCN motion. Reproducibility tests have shown small variations in measurements of the CC motion. PCMRI can be used to assess the VCN motion at the level of the cerebello-pontine angle.

Pulsed arterial spin labeling applications in brain tumors: practical review.

Few institutions use MRI perfusion without contrast injection called arterial spins labeling (ASL) routinely in clinical setting. After general considerations concerning the different ASL techniques and quantitative issues, we will detail a pulsed sequence that can be used on a clinical 1.5-T MR unit. We will discuss and illustrate the use of ASL in tumoral diseases for diagnosis, gliomas grading, stereotactic biopsy guidance and for follow-up after treatment.

Epidemiologic aspects of arterial hypertension in Maracaibo, Venezuela.

The purpose of this study was to determine the prevalence of arterial hypertension (HT) awareness and the influence of age, sex and body mass index on the degree of control of HT in the population of Maracaibo, State of Zulia, Venezuela. It included 7424 subjects, 3640 males (M) and 3784 females (F). Information was collected through domiciliary visits with a questionnaire designed for this purpose. Hypertension was defined as such when values were > or =140 mm Hg for systolic blood pressure (SBP) and > or =90 mm Hg for diastolic blood pressure (DBP). In the total sample, 36.9% were hypertensive. A higher prevalence in M (45.2%) than in F (28.9%), was observed. The percentage of HT increased with age in both genders. There was a high percentage of hypertensives with obesity (73.5%) which did not vary when discriminating for gender and age. Obese subjects were more prone to have HT until age 50. Those younger than 40 took less medication but were proportionally better controlled. Of the hypertensive population 54.3% were not aware of their condition, of 45.7% remaining, 22.8% did not have regular control visits, 18.4% inspite of medication were not controlled and only 4.5% were well controlled. Better control was observed in F (6.2%) than in M (3.3%), P < 0.001. It is concluded that HT is a serious public health problem because of its high prevalence and lack of control, and it is necessary to implement educational and medical programmes for the detection and control of this disease.

Deformation analysis to detect and quantify active lesions in three-dimensional medical image sequences.

Evaluating precisely the temporal variations of lesion volumes is very important for at least three types of practical applications: pharmaceutical trials, decision making for drug treatment or surgery, and patient follow-up. In this paper we present a volumetric analysis technique, combining precise rigid registration of three-dimensional (3-D) (volumetric) medical images, nonrigid deformation computation, and flow-field analysis. Our analysis technique has two outcomes: the detection of evolving lesions and the quantitative measurement of volume variations. The originality of our approach is that no precise segmentation of the lesion is needed but the approximative designation of a region of interest (ROI) which can be automated. We distinguish between tissue transformation (image intensity changes without deformation) and expansion or contraction effects reflecting a change of mass within the tissue. A real lesion is generally the combination of both effects. The method is tested with synthesized volumetric image sequences and applied, in a first attempt to quantify in vivo a mass effect, to the analysis of a real patient case with multiple sclerosis (MS).

Plasma norepinephrine, myocardial damage and left ventricular systolic function in Chagas' heart disease.

The functional status of the sympathetic nervous system in Chagas' heart disease is still the subject of intense controversy. To determine the nature of the abnormalities of the sympathetic nervous system, we measured the plasma norepinephrine concentration of chagasic patients with varying degrees of myocardial damage. Thirty-six patients with positive serology for Chagas' disease were studied. Twenty patients were in Functional Class I (New York Heart Association), 10 were in Functional Class II and six were in Functional Classes III-IV. Cardiac catheterization was performed in 24 patients. The asymptomatic patients had a plasma norepinephrine concentration (121 +/- 37 pg/ml, mean +/- S.D.) not different from normal controls (103 +/- 59 pg/ml). The symptomatic patients, however, had a significantly elevated plasma norepinephrine concentration (665 +/- 354 pg/ml, P < 0.001). The baseline heart rate of the asymptomatic and symptomatic patients directly correlated with the plasma norepinephrine concentration (r = 0.69, P < 0.0001). The symptomatic patients had larger ventricular volumes, higher left ventricular end-diastolic pressures and lower ejection fractions than the asymptomatic patients and normal controls. The plasma norepinephrine concentration correlated linearly with the left ventricular end-diastolic volume (r = 0.77, P < 0.0001), and non-linearly with the ejection fraction (r = -0.70, P < 0.0001) and the left ventricular end-diastolic pressure (r = 0.53, P < 0.007). These results indicate that, in Chagas' heart disease as in most other cardiac diseases, sympathetic nervous system activation is a late and compensatory phenomenon. In other words, sympathetic activation is very likely related to the progressive impairment of left ventricular function.

Automatic measurement of changes in brain volume on consecutive 3D MR images by segmentation propagation.

This article presents a technique to automatically measure changes in the volume of a structure of interest in successive 3D magnetic resonance (MR) images and its application in the study of the brain and lateral cerebral ventricles. The only manual step is a segmentation of the structure of interest in the first image. The analysis comprises, first, precise rigid co-registration of the time series of images; second, computation of residual deformations between pairs of images; third, automatic quantification of the volume change, obtained by propagation of the segmentation of the structure of interest through the series of MR images. This approach has been applied to monitor changes in the volume of the brain and lateral cerebral ventricles in a healthy subject and a patient with primary progressive aphasia (PPA). Results are consistent with those obtained by application of the boundary shift integral (BSI) and by stereology in the same subjects.

[Epidemiological aspects of arterial hypertension among the adult population of Maracaibo City]. / Aspectos epidemiológicos de la hipertensión arterial en la población adulta del Municipio Maracaibo.

The purpose of this study was to determine the prevalence of arterial hypertension (H) and its distribution according to gender, age group, body mass index (BMI) in the population of Maracaibo, Venezuela. 7.424 subjects were included, 3.640 males (M) and 3.784 females (F). Information was collected by means of domiciliary visits with a History and Physical Exam designed for this purpose. H was defined as Systolic Blood Pressure > or = 140 mmHg and/or Diastolic Blood Pressure > or = 90 mmHg. A prevalence of 36.9% of H in the total sample was found with a higher prevalence in M, 45.2%, than in F 28.9%. It increased progressively with age in both genders. Only 4.5% of hypertensive patients were well controlled, 41.2% of patients diagnosed as hypertensive, were not well controlled (DBP > or = 90 mmHg), and 54.3% hypertensives did not know about their condition. Patients with BMI > or = 25 Kg/m2 had a prevalence twice as patients with BMI < 25 Kg/m2 (47.6% Vs 24.2%). It is concluded that H is a serious problem of public health because of it's high prevalence and lack of control, and it is necessary to implement educational and medical programs for the detection and control of this disease.

[Nutritional and metabolic factors as risk factors for cardiovascular diseases in an adult population in the city of Maracibo, Estado Zulia, Venezuela]. / Factores nutricionales y metabólicos como riesgo de enfermedades cardiovasculares en una población adulta de la ciudad de Maracaibo, Estado Zulia, Venezuela.

To analyze the nutritional and metabolic risk factors for Cardiovascular Diseases (CVD) present in a group of people in the city of Maracaibo a study was performed with 209 volunteers (145 women and 64 men) between 20 and 89 years of age who underwent: a) Anthropometric Evaluation: Body Mass Index (BMI) and Waist-to-Hip Ratio (WHR) and Physical Examination: Systolic (SBP) and Diastolic Blood Pressure (DBP); b) Dietetic Evaluation (24 hours recall), and c) Biochemical Evaluation: Glycemia (GLYC), Triglycerides (TG), Total Cholesterol (CHOL), HDL-C, LDL-C and VLDL-C, applying enzymatic methods. It was also investigated, their Age, Family History of Metabolic Alterations (FHMA), physical activity, smoking habits and alcohol consumption. More than 50% of the individuals showed a BMI > 25; 64% of women showed a WHR value > 0.8; 34 and 28% of men and women respectively had a high fat ingestion (HFI); 36% of men had hypertriglyceridemia and high levels of VLDL-C; 41% of women and 30% of men showed decreased HDL-C. A high frequency of FHMA was found in 85% of women and 78% of men followed by sedentary life in 64% of men and 79% of women. The age significantly (p < 0.05) affected the values for WHR, SBP, DBP, GLYC, CHOL, TG, HDL-C, LDL-C and VLDL-C. The dietetic evaluation showed a diet that was low in calories, high in protein, normal in fat and low in carbohydrates. It is concluded that the population elected for this study might be considered under a high risk for CVD, since both nutritional and metabolic factors, as well as the other risk factors analyzed, were present in a high percentage of the individuals studied.