ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1993.tb03316.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1993.tb03317.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

SUMMARYThe efficient stereological procedure for estimating the length densityLvof lineal microstructural features is further improved: the length density of long or short (or those of any arbitrary geometry) lineal features can now be estimated from the measurements performed on the projected images of vertical and horizontal slices of unknown and variable thickness. It is not necessary to identify uniquely the intersections of the lineal features with the parallel faces of the slices in the projected images and distinguish them from the images of the feature end points contained in the slices. The new technique does not involve any assumptions, and it is applicable to the lineal features of any arbitrary geometry and anisotropy. As a ‘bonus’, the same input measurements also yield an assumption‐free estimate of the total number of true lineal‐feature end points per unit volumeEv, and the average slice th

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1993.tb03318.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

SUMMARYPractical, unbiased stereological methods are described to estimate lung volume and external surface area, and total volume and surface area of relatively large and anisotropic structures (bronchi and arteries) inside the lung.The volume of each of five lung strata was estimated first by fluid displacement and then by computed tomography (CT) using Cavalieri's method; the reliability of CT was assessed through a calibration procedure, and image thresholding criteria for an accurate volume estimation using CT were established. The parallel, perfectly registered CT section images were also used to estimate the external surface area of each stratum by the spatial grid method.Unbiased estimation of internal surface areas in lung is a long‐standing problem: since the structures are large and essentially void, large sections are needed; to facilitate identification, thin sections have to be used for light microscopy, and since such structures are anisotropic, the sections should be vertical. A practical stereological design is demonstrated here on an infant lung, which fulfils all these requirements.This study illustrates the potential of using unbiased stereology to characterize infant pulmonary hypoplasi

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1993.tb03319.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

SUMMARYA problem of current medical interest is how to estimate the volume of an object from coaxial sections. Such images can be produced in ultrasound scanning, when the planar scan sections all emanate from a common axis. Two unbiased volume estimators for this sampling regime, previously published without derivation, are derived and presented here in some detail. The estimators are based on an ancient theorem of Pappus of Alexandria (c.ad 320). One of the estimators was used to estimate the volume of urine in the bladder of six human volunteers. The case example was attractive because the corresponding volumes could be voided and directly measured after the scanning session, thus confirming the unbiasedness of the estimator used. Sample size guidelines are also given.

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1993.tb03320.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

SUMMARYThe mean particle volume can be stereologically estimated using the nucleator principle. In the present paper, we discuss another principle for estimating mean particle volume, namely the rotator. The vertical rotator has already been previously described and is supplemented in the present paper by the isotropic rotator. For a collection of particle profiles, simulations show that the variance of the rotator is smaller than that of the nucleator.

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1993.tb03321.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

SUMMARYStereological estimators of length and surface area based on measurements in an isotropic slice through a fixed point are described. Measurements of three‐dimensional angles are not needed. The estimators depend only on distance measurements. The variance of the length estimator is studied in some detail. Applications to particle analysis and second‐order stereology are discus

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1993.tb03322.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

SUMMARYThe first part of the present paper is aimed at a unified introduction of various random distances in a system of disjoint particles in ℝdor in its bounded subset. A general formula for the distribution function of distances is given and applied to several particular situations.In the second part, the detailed results for three selected types of random as well as regular structures are presente

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1993.tb03323.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

SUMMARYReal or reconstructed porous media can be discretized as a series of elementary cubes, which are filled either with a solid or a fluid phase. Various algorithms, based on pseudo‐diffusion processes, are proposed to determine the connected and percolating components of the pore space. The graph of the pore space is obtained by two different methods; the most efficient is based upon homotopic thinning. Topological characteristics, such as the number of loops, are derived. Systematic applications of these algorithms are illustrated on computer reconstructions of various sandstone

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1993.tb03324.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

SUMMARYThe Minkowski dimension as a complexity measure, and its relation to the other dimensions in the case of self‐similar fractal objects, is discussed. An implementation of the Minkowski dimension, using morphological operations on a square grid, is presented. The effect of resolution, orientation and the symmetry of the structuring element used on the estimation of the Minkowski dimension is studied. The corrections required for free end points are presente

ISSN:0022-2720    

DOI:10.1111/j.1365-2818.1993.tb03325.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY