Facial thermography in the diagnosis of cerebrovascular disease and in evaluation of carotid endarterectomy

A computer aided diagnostic method for the evaluation of type II diabetes mellitus in facial thermograms

Almost 50% of individuals around the globe are unaware of diabetes and its complications. So, an early screening of diabetes is very important at this current situation. To overcome the difficulties such as pain and discomfort to the subjects obtained from the biochemical diagnostic procedures; an infrared thermography is the diagnostic technique which measures the skin surface temperature noninvasively. Thus, the aim of our proposed study was to evaluate the type II diabetes in facial thermograms and to develop a computer aided diagnosis (CAD) system to classify the normal and diabetes. The facial thermograms (n = 160) including male (n = 79) and female (n = 81) were captured using FLIR A 305sc infrared thermal camera. The Haralick textural features were extracted from the facial thermograms based on gray level co-occurrence matrix algorithm. The T_ROI, T_MAX, and T_TOT are the statistical temperature parameters exhibited a significant negative correlation with HbA1c (r = - 0.421, - 0.411, - 0.242, p < 0.01 (T_ROI); r = - 0.259, p < 0.01(T_MAX) and - 0.173, p < 0.05 (T_TOT)). An optimal regression equation has been constructed by using the significant facial variables and standard HbA1c values. The model has achieved sensitivity, specificity, and accuracy rate as 91.42%, 88.57%, and 90% respectively. The anthropometrical variables, extracted textural features and temperature parameters were fed into the classifiers and their performances were compared. The Support Vector Machine outperformed the Linear Discriminant Analysis (84.37%) and k-Nearest Neighbor (81.25%) classifiers with the maximum accuracy rate of 89.37%. The developed CAD system has achieved 89.37% of accuracy rate for the classification of diabetes. Thus, the facial thermography could be used as the basic non-invasive prognostic tool for the evaluation of type II diabetes mellitus.

The Potential Role of Thermography in Determining the Efficacy of Stroke Rehabilitation

INTRODUCTION

Maintaining good physiological circulation in the extremities requires an optimally functioning muscle pump. Stroke symptoms indicate a change in venous circulation. In this study, changes were measured in joint function and microcirculation, and the correlation between them was examined.

SETTING

Physiotherapy Center, Ss. Cosmas and Damian Rehabilitation Institute, Visegrád, Hungary.

METHODOLOGY

Sixteen randomly selected poststroke patients with hemiparesis affecting mainly the upper extremities began undergoing rehabilitation 13 ± 4 days following stroke. Thermograms were taken with a Fluke Ti 20 (Fluke Corporation, WA) pretreatment and post-treatment, and a physiotherapy documentation form was completed. Treatment comprised 15 physiotherapy, massage, and galvanic therapy sessions per patient, with the side exhibiting no neurological symptoms as a control.

RESULTS

Joint function showed significant improvement on the affected side (P < .05). Thermographic examinations revealed microcirculatory dysfunction in the affected extremities in 100% of the cases. Following treatment, temperature increased significantly (P ≥ .5°C) on the affected side. A strong correlation (r) was observed between joint function and temperature change (P < .05).

CONCLUSION

Thermography is shown to be a reliable method for monitoring the effects of stroke rehabilitation treatment. Thermographic testing may enable us to predict the course of the trauma and the efficacy of treatment even at the acute stage.

Ophthalmodynamography and ophthalmodynamometry in neurological practice

Inventarisation of atraumatic methods of analysing the circulation in the carotid region shows that they generally can be classified as physiological or anatomical. Physiological methods focus on blood circulation time or on the pulsating changes in blood pressure, blood velocity, blood vessel diameter and cerebral volume. In this study the reliability of two pressure-dependent methods, namely ophthalmodynamography and ophthalmodynamometry, for the detection of haemodynamically significant carotid stenosis is established. Correct results were found in 78--82% of cases. Ophthalmodynamography, and the advantage of combining this method with ophthalmodynamometry, are more extensively investigated. Although in recent years attention has been focussed on the study of the blood velocity pulsations with the Doppler technique, maximal diagnostic efficacy can be expected from a combination of pressure and flow wave studies. A way to compare all the information contained in the curves can be found in the technique of Fourier analysis. The results obtained by Fourier analysis of the ophthalmodynamographic curves are presented.

Thermal recovery of the skin after cooling

A theoretical model of the skin is used to study the thermal recovery of the skin temperature after cooling. The analytical solution of the partial differential equation describing this model shows that recovery curves can be approximated by a two-exponential curve or even by a mono-exponential curve when the data from the first two minutes are omitted. With this model, it is possible to study the influence of the blood flow and the thermal conductivity lambda of the skin on the steady-state temperature and the decay constants mun. New experiments will be carried out to verify the relation between mu1, mu2 and the blood flow but now correcting for the influence of lambda, as predicted by the model.

Doppler haematotachography: problems in interpretation and new applications

The Doppler-echographic examination (HTG) seems to be developing into a screening method for the detection of abnormalities of the large cerebropetal vessels. An appraisal is made of the possibilities and limitations of the HTG based on the literature, a group of 250 patients and several relevant case histories. In general an abnormal HTG curve seems to warrant further diagnostic investigations (angiography). A normal HTG curve not be considered sufficient reason to omit an angiographic examination. A number of new applications of the HTG examination are mentioned.