Estimation Of Wall Thickness Research Articles

Thickness of bone formed at remodeling sites in normal human iliac trabecular bone: Variations with age and sex

The thickness of the bone walls formed at completed remodeling sites was estimated by morphometry in iliac trabecular bone from 85 normal individuals (48 women and 37 men) aged 18–90 years. The mean three-dimensional (3-D) wall thickness was 59.4 ± 5.9 μm. No sex difference was observed. The wall thickness decreased with age: Thickness ( μm) = 65.56 μm. − 0.14 μm/ yr × age (yr). This reduction may lead to a loss of bone with increasing age. The coefficient of variation in completed wall thickness between individuals of the same age was 7%. The factors controlling the thickness are largely unknown, but it was noted that the intraindividual distributions of linear 3-D wall thickness (proportional to the mass of the wall) were symmetric, while distributions of reciprocal 3-D thickness (proportional to the conductivity for oxygen and waste products) were markedly rightskewed. A subgroup comprising 42 individuals aged 18–56 years had been double labeled with tetracycline. The average 3-D calcification rate was 0.63 ± 0.11 μm/day. No relationship to age or sex was demonstrated. Based on the estimates of completed wall thickness and calcification rate, the mean duration of calcification at remodeling sites was calculated to be approximately 100 days.

Measurements of the Human Anterior Chest Wall by Ultrasound and Estimates of Chest Wall Thickness for Use in Determination of Transuranic Nuclides in the Lung

The low energy photons on which the in vivo detection of plutonium isotopes and americum-214 is based are severely attenuated in body tissues. To assess the activity of these radionuclides in the lungs by external measurements it is necessary to estimate or measure the thickness of tissues overlying the lungs. It is also desirable to distinguish between muscle and adipose tissues in the chest wall because of the difference in their attenuation properties. Diagnostic ultrasound machines developed for medical use are suitable for this purpose. Ultrasonic measurements of check wall thickness have been made at this laboratory since 1978. This paper summarises our experience of these measurements and describes our present procedure for making the measurements. The concept of 'equivalent muscle chest wall thickness' is introduced and a method for calculating the parameter is given. Both chest wall thickness and equivalent muscle chest wall thickness have been found to correlate well with Quetelets Index (weight divided by height squared). Residual correlations with other parameters have been examined. Empirical formulae are given that can be used to predict the chest wall thickness and equivalent muscle chest wall thickness of a subject of given weight, height and age.

Spatial voltages in the assessment of left ventricular hypertrophy (Frank system)

The existence of a relationship between surface potentials in the QRS complex on one hand, and left ventricular weight and wall thickness on the other was demonstrated in 150 individuals studied by orthogonal electrocardiography (Frank lead system) and biplane angiocardiography. Equations for the estimation of left ventricular weight and wall thickness were derived from data on that same series. They were based on two simple spatial voltage criteria together with the subject's age and weight. It was shown that the simple voltage criteria provide rather reliable means of detecting conditions of left ventricular overload. With a cut-off point corresponding to a 5% false positive rate, one of the two criteria had a false negative rate of only 33 % for left ventricular overload. Moreover, only a minority of these false negative subjects had left ventricular hypertrophy in terms of heart weight as a fraction of body weight.