Image quantitative

A positive consequence of multi-image analysis is the recovery of quantitative information. At this point, it should be taken into account that quantitation from images measured in reflection is never as accurate and precise as from images measured in transmission. The more representative the surface scarmed is from the rest of the sample, then the more reliable the quantitative information will be. When referring to quantitative information, it is possible to differentiate between within-image and between-image quantitation. 

Figu re 2.18 (a) Scheme followed to obtain within-image quantitative information % of signal contribution) ... 

Concentration measurements may be made after calibration with samples of known thickness and uniform absorber concentration. Other sources of contrast such as diffraction effects Ccin be detected by comparing uv cind visible light images. Quantitative measurements can also be made in fluorescence though care must be taken to avoid saturation which occurs at high concentrations where most of the incoming uv is absorbed. 

An SEM system with the various detectors can provide high-resolution imaging, quantitative elemental analysis of the bulk material, and fast elemental mapping, as well as other benefits. 

Recently, we undertook a comprehensive evaluation of these various forms of image quantitation in gene expression imaging studies of the lungs and compared the results with in vitro assays of the expression of TK enzyme activity (71). In this analysis, we found that the pulmonary uptake of [ F]-FHBG increased as TK enzyme activity increased only at low levels of HSVl-f expression and then plateaued as TK activity continued to increase [Fig. 8.10(A)]. Compartmental modeling failed to improve the correlation with in vitro assays of transgene expression. 

Image analyzing computers are now routinely applied to the measurement of structures observed in microscope images. Quantitative microscopy involves several steps which all must be considered as part of the analysis. The sample must be prepared and the actual microscopy performed. Key factors are to ensure that the specimen does not change dimension during preparation or duing microscopy, that a rep-... 

The within-image quantitation is more correctly described as the signal contribution of a certain constituent to the overall signal. The relative signal contribution over the global image signal can be expressed by sq (%) defined as... 

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