Antonio Pose-Reino

Computerized measurement of retinal blood vessel calibre: description, validation and use to determine the influence of ageing and hypertension.

Objective To validate a computer-based method for measuring the calibre of retinal blood vessels, and use it to determine the effects of ageing and arterial hypertension on the calibres of these vessels and on their ratio. Methods Digital eye fundus images covering a 50° field and centred on the optic disc were obtained using a 540 nm filter. The boundaries of blood vessels crossing a series of circles concentric with the optic disc were located by an image analysis program; the calibres of vessels crossing the circles perpendicularly were determined automatically, the average arteriole and average vein calibres were calculated, and the arteriovenous ratio (AVR) was calculated as the ratio of these averages. The within-operator, between-operator and within-eye reliability of this method was investigated using images of 30 or 40 eyes; the effects of ageing on average vessel calibres and AVR using both eyes of each of 120 normotensive volunteers aged 10–69 years (60 males, 60 females); and the effects of arterial hypertension using a group of 54 hypertensive patients aged 50.9 ± 13.9 years. Results Within-operator, between-operator and within-eye correlation coefficients for AVR were all better than 0.95, and the corresponding coefficients of variation were all better than 3%. The results of Bland Altman approach show a very good agreement. There were no significant differences between right and left eyes or between the sexes in either the normotensive or the hypertensive group. In the normotensive group, vein calibre was almost constant (111 ± 6 μm), but arteriole calibre and AVR fell significantly from 96 ± 6 μm and 0.870 ± 0.046, respectively, in the second decade of life to 85 ± 4 μm and 0.761 ± 0.044 in the seventh decade. Arterial hypertension was not associated with changes in vein calibre, but was associated with decreases in arteriole calibre (from 91 ± 7 μm among normotensive individuals to 84 ± 2 μm) and AVR (from 0.816 ± 0.056 to 0.755 ± 0.027). Age significantly modulated the AVR-reducing influence of hypertension (P = 0.003). Conclusion The proposed method of measuring retinal blood vessel calibres is reliable and precise (especially for the AVR). In this study, its results confirmed that increasing age and arterial hypertension are both associated with reductions in retinal arteriole calibre and AVR.

Development of an automated system to classify retinal vessels into arteries and veins

There are some evidence of the association between the calibre of the retinal blood vessels and hypertension. Computer-assisted procedures have been proposed to measure the calibre of retinal blood vessels from high-resolution photopraphs. Most of them are in fact semi-automatic. Our objective in this paper is twofold, to develop a totally automated system to classify retinal vessels into arteries and veins and to compare the measurements of the arteriolar-to-venular diameter ratio (AVR) computed from the system with those computed from observers. Our classification method consists of four steps. First, we obtain the vascular tree structure using a segmentation algorithm. Then, we extract the profiles. After that, we select the best feature vectors to distinguish between veins and arteries. Finally, we use a clustering algorithm to classify each detected vessel as an artery or a vein. Our results show that compared with an observer-based method, our method achieves high sensitivity and specificity in the automated detection of retinal arteries and veins. In addition the system is robust enough independently of the radii finally chosen, which makes it more trustworthy in its clinical application. We conclude that the system represents an automatic method of detecting arteries and veins to measure the calibre of retinal microcirculation across digital pictures of the eye fundus.

Sirius: A web-based system for retinal image analysis

PURPOSE Retinal image analysis can lead to early detection of several pathologies such as hypertension or diabetes. Screening processes require the evaluation of a high amount of visual data and, usually, the collaboration between different experts and different health care centers. These usual routines demand new fast and automatic solutions to deal with these situations. This work introduces Sirius (System for the Integration of Retinal Images Understanding Services), a web-based system for image analysis in the retinal imaging field. METHODS Sirius provides a framework for ophthalmologists or other experts in the field to collaboratively work using retinal image-based applications in a distributed, fast and reliable environment. Sirius consists of three main components: the web client that users interact with, the web application server that processes all client requests and the service module that performs the image processing tasks. In this work, we present a service for the analysis of retinal microcirculation using a semi-automatic methodology for the computation of the arteriolar-to-venular ratio (AVR). RESULTS Sirius has been evaluated in different real environments, involving health care systems, to test its performance. First, the AVR service was validated in terms of precision and efficiency and then, the framework was evaluated in different real scenarios of medical centers. CONCLUSIONS Sirius is a web-based application providing a fast and reliable work environment for retinal experts. The system allows the sharing of images and processed results between remote computers and provides automated methods to diminish inter-expert variability in the analysis of the images.

Regression of Alterations in Retinal Microcirculation Following Treatment for Arterial Hypertension

Evaluation of early hypertension‐related alterations in retinal microcirculation has been subjective and poorly reproducible. The authors recently described a semiautomatic computerized system for evaluation of the calibre of retinal blood vessels that has shown very good reproducibility. In the study, this system was used to measure the calibres of retinal arterioles and veins, and their ratio, in a group of 51 hypertensive outpatients before and after 6 months of treatment with losartan or, if required for satisfactory blood pressure control, losartan plus hydrochlorothiazide. Mean retinal arteriole diameter increased from 0.0842±0.003 mm to 0.0847±0.003 mm (p=0.001). Arteriovenous ratio increased from 0.753±0.03 to 0.756±0.03 (p=0.005). This observation suggests regression of early hypertension‐related alterations in retinal microcirculation after 6 months of antihypertensive treatment.

Improvements in retinal vessel clustering techniques: towards the automatic computation of the arterio venous ratio

Retinal blood vessel structure is an important indicator for diagnosis of several diseases such as diabetes, hypertension, arteriosclerosis, or stroke. These pathologies cause early alterations in the blood vessels that affect veins and arteries differently. In this sense, the arterio venous ratio is a measurement that evaluates these alterations and, consequently, the condition of the patient. Thus, a precise identification of both types of vessels is necessary in order to develop an automatic diagnosis system, to quantify the seriousness of disease, or to monitor the therapy. The classification of vessels into veins and arteries is difficult due to the inhomogeneity in the retinal image lightness and the similarity of both structures. In this paper, several image feature sets have been combined with three clustering strategies in order to find a suitable characterization methodology. The best strategy has managed to classify correctly the 86.34% of the vessels improving the results obtained with previous techniques.

Using retinex image enhancement to improve the artery/vein classification in retinal images

A precise characterization of the retinal vessels into veins and arteries is necessary to develop automatic tools for diagnosis support. As medical experts, most of the existing methods use the vessel lightness or color for the classification, since veins are darker than arteries. However, retinal images often suffer from inhomogeneity problems in lightness and contrast, mainly due to the image capturing process and the curved retina surface. This fact and the similarity between both types of vessels make difficult an accurate classification, even for medical experts. In this paper, we propose an automatic approach for the retinal vessel classification that combines an image enhancement procedure based on the retinex theory and a clustering process performed in several overlapped areas within the retinal image. Experimental results prove the accuracy of our approach in terms of miss-classified and unclassified vessels.

Effect of delays on survival in patients with lung cancer

BackgroundThe effect on survival of delays in the consultation, diagnostic and treatment processes of lung cancer (LC) is still under debate. The objective of our study was to analyse these time delays and their possible effect on survival.MethodsA retrospective study has been performed on all patients in our health area diagnosed with LC (confirmed by cytohistology) over 3 years. The delay in specialist consultation (time between start of symptoms and the first consultation with a specialist), hospital delay (time between first consultation and start of treatment) and overall delay (the sum of the previous two delays) were analysed. The influence of each of these delays was calculated using Cox regression, adjusted for other factors.ResultsA total of 415 patients were included. Of these, 92.5% were male and 75.4% were in stages III-B or IV. The overall delay gave a mean of 123.6 days, the delay in consulting a specialist 82.1 days and the delay in hospitalisation was 41.4 days. A greater overall delay or greater hospital delay was associated with longer survival. No relationship was observed between the specialist consultation delay and survival.ConclusionsGlobally analysing all the cases and all the stages with LC, it is seen that longer delays are associated with longer survival. This probably reflects the fact that patients with more symptoms are treated more rapidly.

Blood Pressure Profile and Hypertensive Organ Damage in COPD Patients and Matched Controls. The RETAPOC Study

Background Several studies suggest that there is a pathogenic link between chronic obstructive pulmonary disease (COPD) and cardiovascular diseases. On the other hand, increased sympathetic tone has been described in several respiratory diseases. Our objective was to determine whether hypertension mediated by sympathetic overactivity is a mechanism that explains the association between COPD and cardiovascular diseases. Methods Prospective nested case-control observational study; 67 COPD patients were matched 1:1 by sex and age to controls with smoking history. 24 hour-blood pressure monitoring, urinary catecholamines and their metabolites measurement, echocardiography, carotid ultrasound examination, nocturnal oximetry and retinography were performed. Findings classic cardiovascular risk factors and comorbidities were similarly distributed between cases and controls. No significant differences for blood pressure variables (difference for mean systolic blood pressure: -0·13 mmHg; 95% CI: -4·48,4·20; p = 0·94; similar results for all blood presssure variables) or catecholamines values were found between both groups. There was a tendency for lower left ventricle ejection fraction in the COPD cases, that approached statistical significance (64·8 ± 7·4 vs 67·1 ± 6·2, p = 0·05). There were no differences in the retinal arteriovenous ratio, the carotid intima-media thickness, or the number of carotid plaques, between cases and controls. Fibrinogen values were higher in the COPD group (378·4 ± 69·6 vs 352·2 ± 45·6 mg/dL, p = 0·01) and mean nocturnal oxygen saturation values were lower for COPD patients (89·0 ± 4·07 vs 92·3 ± 2·2%, p < 0·0001). Interpretation Hypertension induced by sympathetic overactivity does not seem to be a mechanism that could explain the association between COPD and cardiovascular disease.

CRONIGAL: Prognostic index for chronic patients after hospital admission

OBJECTIVE We have followed patients admitted to a Polypathology and Advanced Age Unit for two years in order to identify the variables that best define the mortality prognosis at medium-term (1-2years) for chronic and polypathological patients requiring admission at an Internal Medicine Department. METHODS This is an observational, prospective study in clinical practice. Polypathological, chronic or multimorbidity patients were included. The classification of the Spanish Ministry for Health was used in order to classify patients as chronic or polypathological. The Charlson Index and Barthel Index were estimated and the Pfeiffer test was administered. The Spanish PROFUND Index was also used. Logistic regression models and Cox proportional hazard model were built in order to study the influence of prognostic factors on survival. RESULTS A total of 567 patients were included: 333 met polypathological (PPP) criteria and 234 chronic criteria (CC). Mean age was 84.8+7.3years. A total of 469 were followed up, most patients belonged to category E (282), 174 to category A and 118 to category C. The prognosis at one year of our patients can be estimated with 7 variables: age, neoplasia, delirium, Barthel, Pfeiffer, presence of atrial fibrillation, and creatinine. The area under the curve is 0.74. CONCLUSION The variables dementia, neoplasia, delirium at admission, Barthel Index under 60, or deceased spouse have mortality prognosis value at one or two years. An index with 7 variables applicable to chronic and polypathological patients after admission may serve as tool to better manage complex chronic patients and follow them up.

Retinal arteriole-to-venule ratio changes and target organ disease evolution in newly diagnosed hypertensive patients at 1-year follow-up

There is no agreement on the systematic exploration of the fundus oculi (FO) in hypertensive patients, and it is unknown whether the evolution of retinal microcirculatory alterations has prognostic value or not. The aim of this study was to investigate whether the evolution of the arteriole-to-venule ratio (AVR) in newly-diagnosed hypertensive patients is associated with better or worse evolution of target organ damage (TOD) during 1 year. A cohort of 133 patients with newly-diagnosed untreated hypertension was followed for 1 year. At baseline and follow-up, all patients underwent a physical examination, self-blood pressure measurement, ambulatory blood pressure monitoring, blood and urine analysis, electrocardiogram, and retinography. The endpoint was the favourable evolution of TOD and the total amount of TOD, according to the baseline AVR and the baseline and final difference of the AVR. A total of 133 patients were analyzed (mean age, 57 ± 10.7 years; 59% men). No differences were found in the decrease in blood pressure or antihypertensive treatment between quartiles of baseline AVR or baseline-final AVR difference. Patients with a difference between baseline and final AVR in the highest quartile (>0.0817) had a favorable evolution of left ventricular hypertrophy (odds ratio, 14.9; 95% confidence interval, 1.08-206.8) and the amount of TOD (odds ratio, 2.22; 95% confidence interval, 1.03-6.05). No favorable evolution was found of glomerular filtration rate. There is an association between the evolution of the AVR and the favorable evolution of TOD. Patients with greater increase of AVR have significantly better evolution of left ventricular hypertrophy and amount of TOD.